Clinical considerations of the role of palbociclib in the management of advanced breast cancer patients with and without visceral metastases

Background

This report assesses the efficacy and safety of palbociclib plus endocrine therapy (ET) in women with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (ABC) with or without visceral metastases.

Patients and methods

Pre- and postmenopausal women with disease progression following prior ET (PALOMA-3; N = 521) and postmenopausal women untreated for ABC (PALOMA-2; N = 666) were randomized 2 : 1 to ET (fulvestrant or letrozole, respectively) plus palbociclib or placebo. Progression-free survival (PFS), safety, and patient-reported quality of life (QoL) were evaluated by prior treatment and visceral involvement.

Results

Visceral metastases incidence was higher in patients with prior resistance to ET (58.3%, PALOMA-3) than in patients naive to ET in the ABC setting (48.6%, PALOMA-2). In patients with prior resistance to ET and visceral metastases, median PFS (mPFS) was 9.2 months with palbociclib plus fulvestrant versus 3.4 months with placebo plus fulvestrant [hazard ratio (HR), 0.47; 95% confidence interval (CI), 0.35–0.61], and objective response rate (ORR) was 28.0% versus 6.7%, respectively. In patients with nonvisceral metastases, mPFS was 16.6 versus 7.3 months, HR 0.53; 95% CI 0.36–0.77. In patients with visceral disease and naive to ET in the advanced disease setting, mPFS was 19.3 months with palbociclib plus letrozole versus 12.9 months with placebo plus letrozole (HR 0.63; 95% CI 0.47–0.85); ORR was 55.1% versus 40.0%; in patients with nonvisceral disease, mPFS was not reached with palbociclib plus letrozole versus 16.8 months with placebo plus letrozole (HR 0.50; 95% CI 0.36–0.70). In patients with prior resistance to ET with visceral metastases, palbociclib plus fulvestrant significantly delayed deterioration of QoL versus placebo plus fulvestrant, whereas patient-reported QoL was maintained with palbociclib plus letrozole in patients naive to endocrine-based therapy for ABC.

Conclusions

Palbociclib plus ET prolonged mPFS in patients with visceral metastases, increased ORRs, and in patients previously treated for ABC, delayed QoL deterioration, presenting a standard treatment option among patients with visceral metastases amenable to endocrine-based therapy.

Clinical trial registration

NCT01942135, NCT01740427

Abstract P2-06-18: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Kunder R, Fernandez Dunne S, Clutter M, Cristofanilli M, Mendillo M, Vasilopoulos A, Horiuchi D. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-18.

Abstract P3-01-03: Circulating tumor cells (CTCs) with epithelial to mesenchymal transition (EMT) phenotype are associated with inferior outcome in primary breast cancer

Background: CTCs comprise heterogenous population of cancer cells with different clinical and biological value. Epithelial-mesenchymal transition (EMT) leads to generation of cells with cancer stem cell properties and increased resistance to chemotherapy and radiation therapy. While the prognostic value of CTCs with epithelial phenotype was repeatedly demonstrated in primary as well as metastatic breast cancer, prognostic value of CTCs with EMT phenotype (CTC_EMT) remained unknown. The aim of this study was to evaluate the prognostic value of CTCs with EMT phenotype in primary breast cancer (PBC) patients.

Methods: This study included 432 primary breast cancer patients treated by surgery and adjuvant therapy from March 2012 to February 2015. CTC_EMT were detected before surgery by quantitative RT-PCR assay. Peripheral blood mononuclear cells (PBMC) were depleted of hematopoietic cells using RossetteSepTMnegative selection kit. RNA extracted from CD45-depleted PBMC was interrogated for expression of EMT transcription factors (TWIST1, SNAIL1, SLUG, ZEB1) by qRT-PCR. Patient samples with higher EMT genes transcripts than those of healthy donors (n=60) were considered as CTC positive. Herein, we report the impact of CTC_EMT on disease-free survival (DFS).

Results: CTC_EMT were detected in 76 (17.6%) patients. Patients CTC_EMT had significantly inferior DFS compared to patients without CTC_EMT (HR = 2.46, 95%CI 1.29 – 4.68, p = 0.0003). Estimated 2- and 5-year DFS for CTC_EMT negative vs. CTC_EMT positive patients was 93.4% and 85.5% vs. 86.9% and 58.1%, respectively. Prognostic value of CTC_EMT was demonstrated in all subgroups of patients, most pronounced in hormone receptor positive, HER2 negative subgroup. In multivariate analysis, presence of CTC_EMT, axillary nodal involvement and hormone receptor status were independently associated with DFS (Table 1).Presence of CTC_EMT was not associated with any patients/tumor characteristics except p53 status (CTC_EMT were present in 20.7% of p53 negative vs. 12.4% p53 positive tumors, p = 0.04).

Conclusions: In this translational study, we demonstrate for the first time the prognostic value of CTC with EMT phenotype in primary breast cancer. Presence of CTC_EMT could lead to better identification of patients with increased risk of recurrence, especially in hormone receptor positive, HER-2 negative primary breast cancer patients.

Multivariate analysis of factors associated with disease free survivalVariableHR (95%CI)P – valueCTC with EMT phenotype  Present vs. absent2.46 (1.48-4.10)0.0005N stage  N+ vs.N02.92 (1.78-4.76)0.00001ER/PR status  Positive for either vs. Negative for both0.40 (0.23-0.71)0.001

Citation Format: Mego M, Jurisova S, Karaba M, Minarik G, Benca J, Sedlackova T, Pindak D, Cristofanilli M, Reuben JM, Mardiak J. Circulating tumor cells (CTCs) with epithelial to mesenchymal transition (EMT) phenotype are associated with inferior outcome in primary breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-03.

Abstract P4-01-04: ESR1 mutation in cell free DNA (cfDNA) is associated with significantly increased circulating tumor cell (CTC)-clusters and progress in stage III/IV breast cancer after systemic treatments

Introduction: CTCs play a critical role in the process of tumor metastasis, and a portion of CTCs may form clusters that contain two or more CTCs bound together which were reported to have up to 50-fold of potential of forming distant metastasis in breast cancer (MBC) as compared to individual CTCs. However, molecular and genomic characterization of CTCs cluster remain largely unknown. Here we report a highly significant correlation between ESR1 mutation in cfDNA, CTCs count and CTC-cluster, which may help to understand MBC metastasis and predict treatment benefit, especially for metastatic or recurrent disease.

Methods: A total of 80 whole blood samples (7.5ml/each) were collected from 80 patients with stage III/IV BCa after informed consent under IRB-approved trial at the RHLCCC at Northwestern University before and after systemic therapies. Among these 80 patients, 41 patients received chemotherapy and 23 patients received endocrine therapy, among which 20 patients received combo treatments (16 plus Palpociclib, 1 plus Ribociclib, 2 plus Everolimus, and 1 plus trastuzumab). CTC enrichment and enumeration were performed in CELLTRACKS ANALYZERII® System (Menarini) by using CTC Kit Meanwhile, we detected the ESR1 hotspot mutations (Y537S and D538G) in plasma cfDNA from all 80 patients by Droplet digital PCR (ddPCR) assay using the QX200 ddPCR System (Bio-Rad). cfDNA was isolated from 2 mL of plasma using the QIAamp Circulating Nucleic Acid Kit (Qiagen) and the MAF was analyzed using QuantaSoft software (Bio-Rad).Database of CTCs and ESR1 mutation was linked with clinical database. Kruskal-Wallis test was used for statistics.

Results: Of the 80 samples analyzed, there were 57 samples without ESR1 mutations (Group 1), and 23 samples that had ESR1 mutations (8 Y537S mutations and 23 D538G mutations, Group 2). CTC positive (≥5) were detected in 13/57 samples (Group 1) and 15/23 samples, and the average amounts of CTCs were 21.77 CTCs/each sample and 59.86 CTCs/each sample in Group 1 and Group 2 respectively. There was a significant association between ESR1 mutations and high level of CTCs (P=0.000088). More important, CTC-clusters were found in 3 samples in Group 1 (5.26%) and in 5 samples in Group 2 (21.74%) respectively. There was a significant correlation between ESR1 mutations and CTC-clusters (P=0.026). Furthermore, there were 18/57 patients in group 1 and 5/23 in group 2 receiving chemotherapy. Moreover, 26/57 in group 1 and 15/23 in group 2 that received chemotherapy. Our results also confirmed that both endocrine therapy and chemotherapy benefited more patients without ESR1 mutations in compared with patients with ESR1 mutations (P<0.05).

Conclusion:We first elucidated the association between ESR1 mutations in ctDNA and CTC-cluster in MBC patients, and provides new insights on the molecular mechanisms associated with the metastasis process. In addition with the highly significant association between ctDNA ESR1 mutations and endocrine resistance we describe a new association allowing to expand the prognostic and predictive role of both tests enabling monitoring the metastatic prognosis and endocrine resistance for clinical decision-making.

Citation Format: Zhang Q, Gerratana L, Zhang Y, Flaum L, Shah A, Davis A, Behdad A, Gradishar W, Platanias L, Cristofanilli M. ESR1 mutation in cell free DNA (cfDNA) is associated with significantly increased circulating tumor cell (CTC)-clusters and progress in stage III/IV breast cancer after systemic treatments [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-04.

Abstract P5-17-03: How is inflammatory breast cancer (IBC) different? Integration of clinico-pathological features and circulating tumor cells (CTCs)-based biomarkers for disease and prognostic assessment

Background: Since IBC is rare and burdened by a particularly unfavorable prognosis, biomarkers able to enhance diagnosis and risk assessment are of pivotal importance and a current unmet need. The aim of this study is to integrate standard clinico-pathological features with CTCs-based biomarkers for a more objective and detailed characterization of IBC.

Methods: This study analyzed retrospectively 251 Advanced Breast Cancer (BC) patients (pts) longitudinally characterized for CTCs and CTCs-based biomarkers at Thomas Jefferson University (Philadephia, PA) and Northwestern University (Chicago. IL). CTCs were enumerated through the CellSearch system (Menarini Silicon Biosystems), and characterized for HER2 expression using the CellSearch CXC Kit. Pts were defined as stage IV aggressive based on the previously reported ≥5 CTCs cut-off (Davis et al. 2018). Associations between clinical features, CTC-derived biomarkers and IBC were tested through uni and multivariate logistic regression. Survival was tested though log-rank test.

Results: Within the analyzed cases, 46% were diagnosed with IBC and among them, 38% was stage IV aggressive. CTC clusters (CTC_CL) were detectable in 12.5% of pts and HER2 positive CTCs (HER2_CTC) in 29.5%. Notably, IBC patients (pts) had a significantly lower CTC count with respect to non-IBC (median 2.5 vs 0 respectively for non-IBC and IBC; P=0.019). BC subtype (HER2 positive BC: OR 2.97; Triple negative BC: OR 2.13), liver and bone involvement (liver: OR 0.46; bone involvement: OR 0.31) were the only significant clinico-pathological features associated with IBC at univariate logistic regression. Interestingly, a marginal significance was observed for soft tissue involvement (OR 1.65, 95%CI 0.95 - 2.87, P=0.07). Stage IV aggressive and presence of HER2_CTC at baseline were moreover inversely associated with IBC. The multivariate model confirmed the significant association between IBC and HER2 positive BC subtype (OR 2.64, 95%CI 1.08 - 6.48, P=0.034), absence of bone involvement (OR 0.31, 95%CI 0.14 - 0.68, P=0.003) and absence of HER2_CTC (OR 0.38, 95%CI 0.15 - 0.98, P=0.045). The baseline detection of CTC_CL was a strong predictor of prognosis for OS in IBC pts (median OS (mOS) 7.6 months (mts) vs not reached (NR) respectively for detectable vs non-detectable CTC_CL; P<0.0001), while a trend was observed for HER2_CTC (mOS 9.9 mts vs NR respectively for detectable vs non-detectable HER2_CTC; P<0.082). Pts negative for CTC_CL at baseline had higher odds of developing CTC_CL in later time-points if stage IV aggressive (OR 12.27, 95%CI 2.10 - 71.57, P=0.005). Despite no baseline factors were significantly associated with the onset of HER2_CTC in later time-points, a trend (P=0.05) was observed for patients without lymph node involvement (OR: 5) and with bone involvement (OR: 4.3).

Conclusion: HER2_CTC and in particular CTC_CL are promising prognostic predictors in IBC. Stage IV aggressive IBC pts could benefit from a longitudinal CTCs assessment, being more prone to develop CTC_CL and therefore at higher risk of rapid disease progression. Probably due to the tropism for soft tissue, IBC is characterized by a lower number of HER2_CTC.

Citation Format: Gerratana L, Zhang Q, Wang C, Shah A, Davis AA, Ye Z, Zhang Y, Abu-Khalaf M, Flaum L, Strickland K, Rossi G, Behdad A, Gradishar W, Platanias L, Yang H, Cristofanilli M. How is inflammatory breast cancer (IBC) different? Integration of clinico-pathological features and circulating tumor cells (CTCs)-based biomarkers for disease and prognostic assessment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-17-03.

Abstract P3-01-08: HER2-negative metastatic breast cancer with HER2-positive circulating tumor cells (CTCs): A new CTC-defined HER2-positive subgroup

Introduction: CTCs can overexpress HER2 discordant from tumor HER2 expression. We aimed to describe characteristics of a CTC-defined group of pts with metastatic breast cancer (MBC) that is tumor HER2- and CTC HER2+ (HER2 tumor- CTC+).

Methods: We retrospectively analyzed data from pts treated at Northwestern University who had serial evaluation of CTCs and circulating tumor DNA (ctDNA). We included pts with pathologically confirmed HER2- MBC and HER2+ CTCs. CTCs were enumerated with the CellSearch immunomagnetic kit (Menarini Silicon Biosystems), HER2 expression on CTCs was determined using the CellSearch CXC Kit in 7.5 cc whole blood, and ctDNA was analyzed using the Guardant360 NGS assay (Guardant Health).

Results: Among 98 pts with HER2- MBC and CTC analysis, 46 (47%) had at least 1 HER2+ CTC. In this cohort the median age was 53. At initial BC diagnosis, 80% had early stage or locally advanced BC and 20% had de-novo metastatic disease. Baseline histology was 65% ductal, 20% lobular, 2% mixed ductal and lobular, and 13% unknown. Pathology of metastatic tumor was hormone receptor positive (HR+)/HER2- in 78% and triple negative in 22%. Detailed HER2 immunohistochemistry (IHC) and FISH results from metastases were available from 63% of pts of whom 72% had an IHC score of 0 or 1 and 28% had an IHC score of 2 with negative FISH testing. The median time from the most recent pathologic metastatic tumor assessment to the detection of a HER2+ CTC was 6.5 mo. Twenty-two pts had simultaneous (within 8 weeks) HER2- tumor confirmation and HER2+ CTC detection. The median lines of endocrine therapy (ET) for MBC prior to detection of HER2+ CTCs was 1 (range 0-5, 41% no ET, 17% 1 line, 41% >2 lines). Pts received a median of 2 (range 0-10) prior systemic therapies for MBC prior to detection of HER2+ CTCs, (20% 0 lines, 41% 1-3 lines, and 39% >4 lines). Among these 46 pts, CTCs were analyzed longitudinally in 104 samples, with HER2+ CTCs detected in 77 samples. Number of HER2+ CTCs at initial detection ranged from <5 in 24%, 5-50 in 43%, and >50 in 33%, with a median of 11.5 HER2+ CTCs. CTC clusters were noted in 37% of pts. At initial detection the proportion of CTCs that were HER2+ was 0-25% in 13% of pts, 26-50% in 46% of pts, and 51-100% in 41% of pts. Seven pts had ERBB2 aberrations in ctDNA. Of 12 pts with tumor sequencing, 2 had ERBB2 mutations, 1 had ERBB3 amplification, and 1 had overexpression of ERBB3 RNA. After detection of HER2+ CTCs, 18 pts received HER2 directed therapy (with chemotherapy in 13 pts, with endocrine therapy in 4 pts, and as monotherapy in 1 pt). Imaging demonstrated a partial response or stable disease in 9 pts (clinical benefit rate 50%), including in 1 pt with trastuzumab monotherapy, progressive disease in 8 pts, and not evaluated in 1 pt.

Conclusions: HER2+ CTCs are frequently detected simultaneously or soon after HER2- tumor assessment in MBC. Within this newly defined subgroup, the several responses seen with HER2 targeted therapy serve as a proof of concept that HER2 tumor- CTC+ patients can benefit from HER2 targeted therapy. Future studies are needed to determine a clinically relevant threshold for HER2+ CTCs to guide further study of HER2 therapy combinations in HER2 tumor- CTC+ pts.

Citation Format: Shah AN, Gerratana L, Zhang Q, Davis AA, Zhang Y, Flaum L, Behdad A, Platanias L, Gradishar WJ, Cristofanilli M. HER2-negative metastatic breast cancer with HER2-positive circulating tumor cells (CTCs): A new CTC-defined HER2-positive subgroup [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-08.

Abstract P1-16-08: Response to subsequent therapy after dual immune checkpoint blockade in metastatic breast cancer

Introduction: While initial studies have found that combining chemotherapy with immune checkpoint blockade (ICB) can augment responses, additional toxicity has been observed. The optimal sequencing of chemotherapy and ICB has not yet been described. Sequential responses to chemotherapy after ICB have been reported in various tumor types; however, data is limited, and this has not been described in breast cancer to date.

Methods: We identified patients (pts) from a small pilot study in HER2-negative metastatic breast cancer (MBC) who received at least 1 cycle of durvalumab (PD-L1 inhibitor) and tremelimumab (CTLA-4 inhibitor). We excluded pts without follow up data or if they did not receive subsequent systemic therapy. Comparison of differences between subgroups was calculated by Fisher's exact test for categorical variables and Wilcoxon rank-sum test for continuous variables. Time to treatment failure (TTF) of subsequent therapy and overall survival (OS) were assessed by the Kaplan-Meier method and differences between breast cancer subtype were compared by log-rank tests.

Results: Twenty-three pts received at least 1 cycle of ICB of whom 14 pts were eligible for this analysis. Nine had estrogen receptor positive (ER+) BC and 5 had triple negative (TN) BC. There were no statistically significant differences between the ER+ and TN subgroups in age, race, ethnicity, ECOG performance status (PS) at end of ICB, or sites of metastatic disease except for more lymph node metastases in the TN cohort (p=0.003). Overall response rates to ICB in this cohort was higher in TN vs ER+ (40% vs 0%, p=0.11). Pts received a median of 4 lines of systemic therapy for MBC prior to ICB. Subsequent therapy after ICB was eribulin in 29%, carboplatin/gemcitabine in 21%, palbociclib + endocrine therapy (ET) in 14%, anthracycline in 14%, ixabepilone +/- capecitabine in 14%, and paclitaxel in 7%. Clinical response was seen in 8 pts (57%), of whom 5 had ER+ BC and 3 had TNBC. The median TTF of subsequent therapy was 3.0 mo (1.9, 5.5), which compared to a median TTF for therapy prior to ICB of 2.5 mo. The median OS was 12.3 mo (2.3-13.3). There were no significant differences between the ER+ and TN cohorts (log-rank test p=0.74 and 0.90 for TTF and OS, respectively. Subsequent therapy was discontinued due to progressive disease in 44%, decline in PS in 19%, liver failure in 6%, treatment related adverse event in 6%, and unknown cause in 13%. Two pts remain on subsequent therapy with palbociclib + ET beyond 6 mo without disease progression. There were no statistically significant differences between TTF >3 mo (n=5) and TTF <3 mo (n=9) subgroups. Pts with TTF >3 mo were numerically more likely to have a PS 0-1 (100 vs 78%), liver metastases (80 vs 56%), and ER+ BC (80 vs 56%). Pts with TTF <3 mo had more lymphopenia (66% vs 20%) and more lines of prior systemic therapy for MBC (median 6 vs 4).

Conclusions: While median duration of response on subsequent therapy was short, a subset of pts had significant clinical responses. These findings provide rationale for prospective validation as they provide strategies for sequencing ICB with standard therapies.

Citation Format: Shah AN, Yalamanchili A, Helenowski I, Bhole S, Woodman J, Gradishar WJ, Cristofanilli M, Santa-Maria CA. Response to subsequent therapy after dual immune checkpoint blockade in metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-16-08.

Abstract P4-01-18: Correlation between circulating tumor DNA (ctDNA) alterations and circulating tumor cells (CTC) uncovers new mechanisms of metastasis for patients with metastatic breast carcinoma (MBC)

Introduction:Novel molecular diagnostics including CTCs and ctDNA have been proved to predict disease metastasis and survival. However, the frequency of detection of actionable mutations using CTCs and ctDNA is variable based upon tumor related factors and diagnostic platform sensitivity. Herein, we evaluated a novel NGS technology in the ability of detecting driver and clonal genomic abnormalities in samples from MBC patients, and compared ctDNA alterations with CTCs and CTC-cluster. This study demonstrated several novel correlation between some specific ctDNA alterations and CTCs or CTCs related biomarkers, which opened new insight on mechanisms of metastasis for MBC.

Methods: This study included 52 samples from 26 patients with stage III/IV BCa treated at NMH (2016-2017) and who received standard systemic treatments based on disease subtypes. Whole blood samples (7.5ml/each) were used for CTC enrichment and enumeration in FDA approved CELLTRACKS ANALYZERII® System (Menarini). ctDNA from clinical plasma samples was analyzed by using PredicinePLUS, a NGS-based assay (Predicine Inc) with a 180-gene panel for genomic alterations mutations. Results of CTCs and ctDNA alterations were linked to clinical database. Matched pairs variations between CTCs and ctDNA alterations was compared by Wilcoxon signed-ranks test and Kruskal-Wallis test.

Results: Genomic Alterations (SNVs, Indels and copy number variations) were detected on 52 genes by PredicinePLUS assay. All samples (100%) demonstrated at least 1 somatic alterations. There were 75 mutations detected within 29 genes, and the variant frequency of mutated genes ranges from 0.11% to 68.56%. Increased CTCs were highly significantly correlated with genomic alterations in the genes (wild type vs alterations) including GATA3 (8vs 37), ESR1 ( 2.5 vs 41.3), CDH1 (3.5 vs 50.5) and CCND1 (4 vs 120) (P<0.01). Decreased CTCs were correlated with alterations of CDKN2A (20.5 vs 0) (P=0.025). CTC-cluster appear associated predominantly with alterations of CDH1 (P=0.0018), CCND1 (P=0.008) and BRCA1 (P=0.04). Furthermore, in HER positive CTCs group, ERBB2 mutations caused increased CTCs in compared with ERBB2 wild type (0 vs 5), when CCND1, CDKN2A, GATA3 and TP53 alterations were associated with increase of HER2 negative CTCs.

Conclusions: By using the novel diagnostic platform with the ability to identify ctDNA mutation and copy number variation, this study demonstrated several novel genes alterations which were highly correlated with CTCs, CTC-cluster and HER2. Some genes (CCND1 and CDH1) got involved into the changes on both CTCs and CTC-cluster, when some genes (CCND1, CDKN2A, ESR1 and GATA3) were related with change of CTCs and HER2 expression. Correlation of CTCs and ctDNA can be reliably and routinely used as non-invasive method for monitoring disease metastasis and predict the prognosis in MBC in clinic.

Citation Format: Davis A, Zhang Q, Gerratana L, Zhang Y, Flaum L, Shad A, Behdad A, Gradishar W, Platanias L, Cristofanilli M. Correlation between circulating tumor DNA (ctDNA) alterations and circulating tumor cells (CTC) uncovers new mechanisms of metastasis for patients with metastatic breast carcinoma (MBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-18.

Abstract P6-03-01: Development of patient-derived xenograft tumor model with organ-specific metastatic potential for evaluation of new therapeutics for hormone receptor-positive advanced breast cancer

Background: Breast cancer (BC) is a heterogeneous disease with most common metastatic sites of liver, lung, brain, and bone. Endocrine resistance in hormone receptor-positive (HR+) advanced BC (ABC) cancer is a clinical challenge. ESR1 mutations are a key mechanism in acquired resistance, primarily occurs after exposure to endocrine therapy such as aromatase inhibitors but also selective estrogen modulators and degraders (i.e. Tamoxifen and Fulvestrant). Circulating tumor cells (CTCs) enumeration is a prognostic biomarker in ABC but the relation between the onset of ESR1 mutations and CTCs status is still unclear. Aim of this project is to define the clinical behavior of ESR1 mutated ABC in terms of metastasizing potential, through CTC enumeration and pattern; and to establish ESR1 mutated HR+ ABC PDX models able to recapitulate these characteristics.

Methods: CTCs and circulating tumor DNA (ctDNA) were characterized in 55 HR+ ABC patients. ESR1 mutations status from 55 patient plasma cell-free DNA were generated using Guardant Next Generation Sequencing. Samples were also examined for numbers of CTCs by CellSearch. Association of ESR1 mutations with sites of distant organ metastasis and with CTC enumeration was analyzed by Chi square test and Kruskal–Wallis test, respectively. In preclinical model development, six samples of pleural effusion-derived tumor cells from Stage IV HR+ ABC patients were collected to establish HR+ ABC with ESR1 mutation PDX tumor model and its derived 3D organoid/spheroid cultures

Results: ESR1 mutations were identified in 10 out of 55 patients (4 Y537S variant and 3 D538G variant, 4 other variants, 1 patient with both variants). In 55 patients, 72 visceral vs 27 bone metastatic incidences were observed; the data indicated 9 observed vs 4.5 expected in ESR1 mutated and 16 observed vs 20.5 expected in wild type (WT) (P=0.003) for liver metastasis; 10 observed vs 7.1 expected in ESR1 mutated and 29 observed vs 31.9 expected in WT (P=0.026) for bone metastasis. Further liver metastasis analysis of individual hot spot mutation site indicated 4 observed vs 1.8 expected in Y537S and 21 observed vs 23.2 expected in WT (P=0.037); and 3 observed vs 1.4 expected in D538G and 22 observed vs 23.6 expected in wild type (P=0.088). The analysis of correlation/distribution between CTCs numbers and ESR1 mutated suggested CTCs median of 13 (IQR 7-49) in ESR1 mutated and 0 (IQR 0-4) in WT HR+ patients (P=0.0044). Four ABC PDX tumor models were developed in immunodeficient NSG female mice demonstrated by pathology to have highly heterogeneous characteristics and metastatic features of the origin patient tumor, in particular, breast fat pad xenografted PDX tumor can result in metastasis to liver and lung tissue. In addition, two patient 3D tumor organoid/spheroid cultures were successfully established.

Conclusions: ESR1 mutated ABC is associated with more aggressive (Stage IV) clinical behavior demonstrated by association with visceral metastases and CTCs detection. ESR1-mutated PDX models recapitulate aggressive features of the disease and can be used for preclinical testing of novel agents in endocrine resistant disease.

Citation Format: Qiang W, Zhong Z, Gerratana L, Zhang Y, Zhang Q, Gursel D, Wei J-J, Bleher R, James C, O'Halloran T, Cristofanilli M. Development of patient-derived xenograft tumor model with organ-specific metastatic potential for evaluation of new therapeutics for hormone receptor-positive advanced breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-03-01.

Abstract P4-01-08: Characterization of circulating tumor free DNA (ctDNA) obtained from patients with metastatic breast carcinoma (MBC) undergoing systemic therapies using comprehensive genomic profiling

Introduction:Therapeutic benefit from individual treatments in patients with MBC is limited to small subsets of patients and of short duration due to tumor heterogeneity. Novel molecular diagnostics including ctDNA has been shown to predict response or resistance and survival. However, the frequency of detection of actionable mutations using ctDNA is variable based upon tumor related factors and diagnostic platform sensitivity (e.g. ddPCR or NGS). We evaluated a novel NGS technology in the ability of detecting driver and clonal genomic abnormalities in samples from MBC patients. Moreover, we wanted to compare the new technology to another state-of-the-art, commercially available diagnostic ctDNA testing with similar sensitivity to demonstrate both are able to detect genomic abnormalities in MBC.

Methods: This study included 30 samples from 15 patients with stage III/IV BCa treated at NMH (2016-2017) and who received standard systemic treatments based on disease subtypes longitudinally characterized for ctDNA before or 3 months after systemic therapies respectively. ctDNA from clinical plasma samples was first analyzed using PredicinePLUS, a NGS-based assay (Predicine Inc) with a 180-gene panel for genomic alterations mutations. The results were then independently analyzed with Guardant360TM (Guardant Health), a 73-gene panel. Matched pairs variations between Guardant360TM and Predicine was compared by Wilcoxon signed-ranks test. The prognostic impact of ctDNA was tested through Cox regression.

Results: Genomic Alterations (SNVs, Indels and copy number variations) were detected on 43 genes by PredicinePLUS assay. All samples (100%) demonstrated at least 1 somatic alterations. There were 75 mutations detected within 29 genes, and the variant frequency of mutated genes ranges from 0.11% to 68.56%. Median variant frequency was around 3.42%. Key cancer related genes including TP53, ESR1, PIK3CA, PTEN and BRCA1, are frequently mutated. Copy number variation were detected on 18 genes, among which 15 genes showed copy number gain, including MYC, PIK3CA, CCND1, and 3 genes (ATM, BRCA1 and CDKN2A) with copy number loss. There were no significant difference of % ctDNA (P=0.3967) and number of variations (P=0.5) between results of Predicine and Guardant360TM, neither to the comparison of main detected alterations (BRCA1, ESR1, MYC, PIK3CA and TP53) with Guardant360TM and Predicine (P=1). Furthermore, results from Predicine indicated that there is correlation with treatment response and benefit. A significant decrease on variations in %ctDNA levels (P=0.028) and variations in the number of genomic variants (P=0.028) after systemic therapies, was associated with longer overall survival.

Conclusions: Our study describes a novel diagnostic platform with the ability to identify ctDNA mutation and copy number variations in patients with MBC receiving systemic therapy. We also confirm that when comparing ctDNA using NGS platforms with similar sensitivity, the results are robust and reproducible which indicates that these technologies can be reliably and routinely used as non-invasive method for monitoring response to systemic therapies and predict the prognosis in MBC.

Citation Format: Zhang Q, Gerratana L, Zhang Y, Flaum L, Gradishar W, Platanias L, Cristofanilli M. Characterization of circulating tumor free DNA (ctDNA) obtained from patients with metastatic breast carcinoma (MBC) undergoing systemic therapies using comprehensive genomic profiling [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-08.

Abstract P3-01-19: HER2-positive circulating tumor cells (CTCs) in advanced breast cancer (BC): A feature independent of BC subtype

Introduction: HER2 overexpression is observed on CTCs in advanced BC (ABC), but their significance is not known. We aimed to describe clinical, pathologic, and molecular associations with HER2 overexpression on CTCs in ABC patients (pts).

Methods: We conducted a retrospective analysis of data from ABC pts treated at Thomas Jefferson University and Northwestern University who had evaluation of CTCs and circulating tumor DNA (ctDNA). CTCs were enumerated with the CellSearch immunomagnetic kit (Menarini Silicon Biosystems), HER2 expression on CTCs was evaluated using the CellSearch CXC Kit, and ctDNA was analyzed using the Guardant360 NGS assay (Guardant Health). Associations with the presence of HER2+ CTCs were explored through univariate and multivariate logistic regression. Kruskal-Wallis testing evaluating HER2+ CTCs as a continuous variable was also conducted to confirm consistency of findings. Time to development of HER2+ CTCs was evaluated using Cox proportional hazards regression analysis.

Results: Baseline CTCs were evaluated in 209 pts (10% stage III, 90% stage IV) of whom 41% had no detectable CTCs, 23% had 1-4 CTCs, and 36% had >5 CTCs (stage IV aggressive). Twelve percent had CTC clusters. At least 1 HER2+ CTC was seen in 33% of pts at baseline draw. Of 39 patients with HER2+ BC, only 18% had HER2+ CTCs. Of patients with HER2+ CTCs, 55% had hormone receptor positive BC, 28% had triple negative BC, and 18% had HER2+ BC. On univariate logistic analysis, BC subtype or HER2 status was not associated with the presence of HER2+ CTCs. IBC pts represented 52% of pts and were less likely to have HER2+ CTCs (OR 0.40 95% CI 0.19-0.84). Bone metastases were associated with an increased likelihood of HER2+ CTCs (OR 2.46, 95% CI 1.12-5.38); however, other sites of metastases and number of metastatic sites were not correlated with HER2+ CTCs. Aggressive disease features including >5 CTCs and presence of CTC clusters were strongly associated with HER2+ CTCs (OR 15.72, 95% CI 6.89-35.8 and 8.97, 95% CI 3.23-24.89, respectively). Of 168 pts with ctDNA analysis, ERRB2 aberrations were seen in 22% of pts and were significantly associated with HER2+ CTCs (OR of 3.74, 95% CI 1.45-9.63). On multivariate analysis, the associations with >5 CTCs and ERBB2 alterations in ctDNA remained statistically significant. The associations of HER2+ CTCs with bone disease, >5 CTCs, CTC clusters, and ERBB2 alterations in ctDNA, and the inverse relationship with IBC were consistent when HER2+ CTCs were evaluated as a continuous variable with Kruskal-Wallis testing. Among pts without HER2+ CTCs at baseline, the time to detection of HER2+ CTCs correlated with the presence of bone metastases (HR 3.40, 95% CI 1.14-10.19), >5 CTCs (3.77, 95% CI 1.33-10.70), and visceral disease (HR 3.00, 95% CI 1.07-8.44).

Conclusions: HER2+ CTCs are common in ABC, independent of HER2 status of the tumor, and, in fact, common in the luminal BC. HER2+ CTCs were also strongly associated with CTC characteristics of aggressive disease with poor survival (CTCs clusters and >5 CTCs) and ERBB2 aberrations in ctDNA. Further studies will be investigating the role of HER2+ CTCs in endocrine resistance and the potential of anti-HER2 therapy in this unique CTC-defined setting.

Citation Format: Shah AN, Gerratana L, Davis AA, Zhang Q, Zhang Y, Rossi G, Wang C, Strickland K, Yang H, Flaum L, Abu-Khalaf M, Behdad A, Ye Z, Platanias L, Gradishar WJ, Cristofanilli M. HER2-positive circulating tumor cells (CTCs) in advanced breast cancer (BC): A feature independent of BC subtype [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-19.

Abstract P3-01-10: Associations between plasma Interleukin 2 (IL-2) and HER2 expression in circulating tumor cell (CTC) and MYC alterations in circulation tumor DNA (ctDNA) open a new insight on immune microenvironment for patients with metastatic breast cancer (MBC)

Introduction: Overexpression of HER2 has been reported to be associated with metastasis and poor prognosis of patients with MBC. We reported in AACR 2018 that HER2 overexpression is associated with CTC-cluster. Preclinical data suggested that MYC and HER2 cooperate to drive stem cell phenotype and poor prognosis in MBC (Nair R). Furthermore, IL-2 upregulates the transcription of MYC (Grigorieva I) and gets involved into its alterations. We reasoned that further understanding of interactions of HER2 in CTC and MYC will be important to elucidate the mechanism of metastasis of MBC. Herein, we report a significant correlation between the plasma IL-2 level and HER2 expression in CTCs, and the IL-2 related MYC ctDNA alterations in MBC.

Methods: This study enrolled 43patients with stage III/IV BCa at the Northwestern Memorial Hospital (2016-2017) that had longitudinally detection of CTCs and ctDNA. Whole blood samples (7.5ml/each) were collected for CTCs enumeration by using CELLTRACKS ANALYZERII® System (Menarini) contains antibodies of anti-EpCAM for capturing CTCs, anti-CK-PE for epithelial cells, DAPI for nucleus, anti-CD45-APC for leukocytes and anti-HER-2/neu-FLU. The CTCs were classified based on phenotype as CK+, EpCAM+, DAPI+ and CD45-.Plasma ctDNA was analyzed using the Guardant360 TM NGS-based assay (Guardant Health), a 73 genes panel. ELISA for IL-2 was performed by using patients' plasma. Database of IL-2, HER2, CTCs and ctDNA was linked with clinical database and analyzed by Kruskal-Wallis test.

Results: CTCs ≥ 5 were found in 20 patients (46%). There were 15 patients that had HER2 negative CTCs (Group 1), and 5 patients had HER2 positive (Group 2) CTCs. The level of IL-2 was much higher in Group 1 (88.17pg) compared to Group 2 (66.81pg), indicating that patients with HER2 positive CTCs have significant lower IL-2 than patients with negative CTCs (P=0.02). Meanwhile, ctDNA MYC alterations were detected in 10 patients (including 1 L114R mutation, 7 CNV and 2 SNV) who have the average IL-2 level as 94.00pg. There were 11 patients without any alterations of MYC had average IL-2 level of 70.17pg, which indicated that patients with alterations in the ctDNA MYC have significant higher level of IL-2 in compared with patients without MYC alterations (P=0.02).

Conclusions: Findings of the correlation between overexpression of HER2 in CTCs and low IL-2 level indicated that low immunity may contribute to more aggressive MBC. And the higher level of IL-2 appear associated predominantly with MYC genomic alterations indicated that overexpression of MYC may also stimulate the immune response by upregulating IL-2 via a reverse feedback pathway. We postulated that increasing IL-2 suppresses the HER2 expression in CTC and breaks cooperation between HER2 and MYC. Although the interactions between them still unknown, our results suggest that IL-2 related immune microenvironment acts as a key player to suppress HER2- and MYC-mediated progress in MBC, including the formation of CTC-cluster. Monitoring and administration of IL-2 may benefit pretreated MBC patients and predict disease metastasis.

Citation Format: Zhang Q, Gerratana L, Zhang Y, Flaum L, Shah A, Davis A, Behdad A, Gradishar W, Platanias L, Cristofanilli M. Associations between plasma Interleukin 2 (IL-2) and HER2 expression in circulating tumor cell (CTC) and MYC alterations in circulation tumor DNA (ctDNA) open a new insight on immune microenvironment for patients with metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-10.

Abstract P4-01-14: Association between interleukin 2 (IL-2) and circulating tumor DNA (ctDNA) is a novel biomarker for patients with metastatic breast cancer (BCa) after systemic therapies

Introduction: The detection and monitoring of ctDNA in metastatic breast cancer showed ability to predict treatment resistance and outcome. But the mechanisms has been a challenge to clinicians. Immune escape and immune tolerance has also been reported to cause BCa progress. Herein, we report a novel finding of the association between plasma IL-2 and the ctDNA in advanced BCa patients who received the systemic therapies, and it is potential utilization in clinic.

Methods: This study enrolled 43 patients with stage III/IV BCa at the Northwestern Memorial Hospital (2016-2017) that had longitudinally detection of ctDNA and circulating tumor cells (CTCs) before (baseline, BL) or 3 months after (first evaluation, FE) systemic therapies respectively. Duplicate whole blood samples (7.5ml/each) were collected in EDTA tubes from these patients. Plasma ctDNA was analyzed using the Guardant360 NGS-based assay (Guardant Health) and CTC enrichment and enumeration were performed in FDA approved semi-automated fluorescence CELLTRACKS ANALYZERII® System (Menarini Silicon Biosystems) by using CELLSEARCH® CXC Kit (Menarini). ELISA (Fisher) for IL-2 was performed by using patients' plasma. Database of IL-2, ctDNA and CTCs was generated and linked with clinical database. Kruskal-Wallis test was used for statistics. We previously reported cut-off of 5.7 was used to dichotomize the prognostic value of ctDNA percentage (%ctDNA) in 2018 ASCO. Matched pairs variations between IL2 levels at BL and at FE were tested through Wilcoxon signed-ranks test. Associations between %ctDNA and IL2 levels were explored through Kruskal-Wallis test. The prognostic impact of IL2 was tested through Cox regression.

Results: CTCs ≥ 5 were found in 23 patients at BL and 21 patients in FE respectively. There were 12 patients that had increase CTCs, and 31 patients with similar or less CTCs FE after systemic therapies. Decreased in CTCs was associated with increased IL-2 (P=0.004).The FE analysis showed that IL-2 dropped significantly in patients with CTC stably ≥5 (from 95.84pg to 79.46pg) after therapies (P<0.001). Furthermore, baselineIL-2 levels were significantly higher in patients with % ctDNA levels ≥5.7 (97.15pg) compared to patients with %ctDNA levels <5.7 (68.64pg) (P=0.0027). No other associations were highlighted in respect to age or number of ctDNA alterations. There was no significant variations between BL and FE levels of IL2 were observed according to BCa subtypes nor in respect to baseline %ctDNA ≥5.7 or CTCs ≥5. Compared with low level of BL IL-2 (<78.3pg) group, high level of BL IL-2 (≥78.3pg) had a significant negative impact on overall survival (OS) (P=0.037) in univariate analysis.

Conclusions: Our findings indicated that aggressive BCa with high level ctDNA mutation are associated with high level of IL-2 and immune response in patients with advanced disease. In addition we confirm a reverse correlation between change of IL-2 and change of CTCs potentially indication of immune escape. In summary, the study shows a dynamic relation between IL-2 level and tumor burden (ctDNA) and immune escape (CTCs) suggesting another potential biomarker to monitor interaction between tumor and immune environment.

Citation Format: Zhang Q, Gerratana L, Zhang Y, Flaum L, Shah A, Davis A, Behdad A, Gradishar W, Platanias L, Cristofanilli M. Association between interleukin 2 (IL-2) and circulating tumor DNA (ctDNA) is a novel biomarker for patients with metastatic breast cancer (BCa) after systemic therapies [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-14.

Abstract P5-17-02: Dissecting the biology of inflammatory breast cancer (BC) through cell free DNA and a circulating tumor cells (CTC)-derived signature

Background: The biological characteristics conferring Inflammatory BC's (IBC) distinctive and aggressive clinical features are currently not fully clarified. The aim of this study is to dissect IBC's biology through the integration of DNA and CTC-based circulating biomarkers.

Methods: This study retrospectively analyzed 251 Advanced BC (ABC) patients (pts) treated and longitudinally characterized for CTCs and circulating tumor DNA (ctDNA) at Thomas Jefferson University (Philadephia, PA) and Northwestern University (Chicago, IL). CTCs were enumerated through CellSearch (Menarini Silicon Biosystems), and characterized for HER2 expression using the CellSearch CXC Kit, while ctDNA was analyzed using the Guardant360 NGS assay (Guardant Health) and its percentage (%ctDNA) was classified based on the previously reported cut-off of 5.7% (Gerratana et al 2018). A subset of 117 pts was further characterized for circulating cell-free DNA (ccfDNA) through Qubit® dsDNA HS quantitation Assay (Thermo Fisher Scientific) and quantitative real-time PCR assay for ALU DNA repeats on chromosome 1.Associations between clinical characteristics, CTCs-derived biomarkers and IBC were explored through Fisher's exact test; survival was tested though Cox regression and log-rank test.

Results: Of the total 251 pts, 115 were diagnosed with IBC. Among the 117 patients characterized for ccfDNA, 70 had IBC. Median ccfDNA was 1.59 for IBC (IQR 1.02-3.19) and 2.37 for non-IBC (nIBC) (IQR 1.13-3.52), P=0.27. Consistent results were observed for %ctDNA levels (median value: 2 vs 1.6). The impact on OS of ccfDNA after log transformation was significant for the total population (HR 1.73 95%CI: 1.11-2.69) but not in IBC pts (HR 1.40 95%CI: 0.84-2.34). On the other hand, ctDNA high pts had a significantly worse OS (nIBC: HR 5.34 95%CI: 1.70-18.81 P=0.004; IBC: HR 4.05 95%CI: 1.91-8.58 P< 0.001). In the ctDNA high subgroup no differences in total number of CTCs were observed between IBC and nIBC, while significantly lower CTCs were observed in ctDNA low IBC pts (P=0.0097). The ctDNA low IBC subgroup had a higher incidence of HER2 positive BC (P=0.003) and a significantly lower incidence of CTCs clusters (P=0.006), HER2 positive CTCs (P=0.041). Notably, no associations were observed with stage at baseline, number of metastatic sites, liver, lung and visceral involvement. On the other hand, the ctDNA_high IBC subgroup was characterized by a lower incidence in liver, bone and visceral involvement (P=0.017, P=0.014 and P=0.03 respectively) and a marginally high incidence in soft tissue involvement (0.084). Moreover, IBC diagnosis conferred a significantly worse prognosis only in the ctDNA low subgroup (OS at 12 months nIBC: 100% vs IBC: 70%; P=0.049), while no differences were observed in the ctDNA_high subgroup (OS at 12 months nIBC: 29% vs IBC: 26%; P=0.767).

Conclusion: ctDNA is able to stratify BC according to aggressiveness independently from the sites and type of metastases, both in the IBC and nIBC subgroups. IBC has a distinctive CTCs/ctDNA-based signature, in particular ctDNAlow pts have a lower incidence of HER2 positive CTCs and CTC clusters. This signature is probably due to predominant lymphatic metastatic spread and aggressive phenotype.

Citation Format: Gerratana L, Zhang Q, Wang C, Shah A, Davis AA, Ye Z, Zhang Y, Abu-Khalaf M, Flaum L, Strickland K, Rossi G, Behdad A, Gradishar W, Platanias L, Yang H, Cristofanilli M. Dissecting the biology of inflammatory breast cancer (BC) through cell free DNA and a circulating tumor cells (CTC)-derived signature [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-17-02.

Abstract PD4-05: Patterns of genomic alterations in ER-positive advanced breast cancer patients treated with CDK4/6 inhibitors

Background:Cyclin D kinase inhibitors (CDK-is) have shown clinical efficacy in estrogen receptor (ER)-positive metastatic breast cancer (MBC) when combined with aromatase inhibition or estrogen receptor (ER) antagonism. Despite the benefit of this approach, clinical resistance develops sometimes early in the treatment without any response to endocrine therapy (primary endocrine resistance) or after initial response (secondary resistance) in all patients in the metastatic setting and the molecular basis for this resistance are still largely unknown. We evaluated the pattern of genomic alterations in circulating cell-free tumor DNA (ctDNA) analysis of metastatic breast cancer patients with ER-positive tumors treated with palbociclib combined with either letrozole or fulvestrant and progressing during therapy.

Methods: We conducted a retrospective study of patients with ER-positive MBC who had longitudinal assessment of their disease by ctDNA analysis. The plasma-based assay was performed utilizing Guardant360 (Guardant Health, CA), a digital NGS technology to sequence a panel of > 50 cancer genes. After tabulating number of genomic alterations detected for every patient at baseline and after CDK-i therapy, analysis was performed to identify molecular profile changes in the entire population and in individuals with early progression of disease (<6 months).

Results: We analyzed data of 15 ER-positive MBC patients: 8 patients received fulvestrant/palbociclib and 7 received letrozol/palpociclib. The most common mutations before CDK-i therapy were: PIK3CA (16%), TP53 (16%), ESR1 (13%), KIT (9%), EGFR (3%), APC (3%), ERBB2 (3%), MYC (3%), PTEN (3%), RB1 (3%). After therapy with CDK-i the pattern of mutations showed stable and persistent incidence of PIK3CA, TP53 and ESR1. However, new mutations where identified: FGFR1 (6%), IDH (2%), BRCA1 (2%), BRCA2 (2%), CCNE (2%), CCND1 (2%), RAF (2%), AR (2%), ALK(2%). Also, the pattern of gene amplifications presented an increased rate of MYC and FGFR1 amp. Patients with progression of disease before 6 months of CDK-i therapy presented baseline higher number and variation of mutations compared to patients with disease controlled beyond 6 months of therapy.

Conclusion: Longitudinal assessment with ctDNA analysis suggest that a genomic alteration landscape consisting of persistent detection of driver and acquired mutations along with emergent new abnormalities in regulatory genes could potentially be related to primary or secondary resistance to CDK-Is in ER+ MBC patients. Future investigation of these alterations should be conducted.

Citation Format: Cruz MR, Limentani K, Taxter T, Santa-Maria CA, Behdad A, Gradishar WJ, Nagy RJ, Cristofanilli M. Patterns of genomic alterations in ER-positive advanced breast cancer patients treated with CDK4/6 inhibitors [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD4-05.

Abstract P2-02-21: The utility and correlation of circulating tumor cells (CTCs) and cell-free circulating tumor DNA (ctDNA) based on HER2 positivity

Background:

CTCs are well-established prognostic and predictive biomarkers for metastatic breast cancer (MBC) and other solid tumors. ctDNA is emerging as a quantitative blood-based biomarker for monitoring genomic alterations and disease progression. We evaluated the clinical utility and correlation of these liquid biopsy molecular tools in a cohort of MBC patients.

Methods:

CTC samples were obtained from an ongoing, prospective study of blood based prognostic biomarkers for breast cancer patients. At this time, 71 patients and 98 total samples have been collected. CTC enumeration was performed using the CellSearchTM platform (Menarini, IT). Within this cohort, MBC patients who had ctDNA testing were identified. ctDNA testing was performed using Guardant360TM (Guardant Health, CA), a digital next-generation sequencing technology. Two groups were analyzed: (1) HER2-negative patients with CTC ≥ 5 in 7.5 ml of blood (2) HER2-positive patients who had been treated with HER2 targeted therapy.

Results:

22 samples (N=16 patients) were found with CTC ≥ 5 (range 8-904) and concurrent ctDNA testing (median timeframe between collection 0 days, range 0-42 days). There was a significant association between number of CTCs and the total number of genomic alterations detected in ctDNA (paired two sample t-test, p=0.012). In addition, CTC enumeration was significantly correlated with somatic alteration burden of the dominant clone (paired two sample t-test, p=0.023). The most common alterations detected in the blood were TP53 (55% of patients, 18 total mutations), PIK3CA (41% of patients, 15 total mutations), and ESR1 (32% of patients, 14 total mutations). For patients with HER2 positivity receiving HER2-targeted therapies (N=16 samples from 11 patients), only 18.8% of samples had detectable CTCs (all less than 5) as compared to 75.0% of samples with detectable ctDNA alterations. In N=12 samples with detectable ctDNA mutations, mean number of genomic alterations was 4.4 with mean somatic mutation burden of 2.95%.

 CTCs detectedctDNA detectedCTC ≥ 5Mean number of ctDNA alterations+Mean somatic alteration burden+HER2- (only cases with CTC ≥ 5)100% (22/22)100% (22/22)100%6.716.1%HER2+ (all cases)18.8% (3/16)75.0% (12/16)0%4.42.95%+excludes ctDNA samples without detected genomic alterations

Conclusions:

In HER2-negative MBC patients, CTC enumeration was significantly correlated with the number of ctDNA genomic alterations and somatic alteration burden, indicating the potential for ctDNA as a prognostic, quantitative biomarker of tumor burden. In patients with HER2 positivity, ctDNA may be a more sensitive liquid biopsy tool given the rarity of detecting CTCs detection in this population using the CellSearchTM system. In HER2-positive patients, consideration of size-dependent selection of CTCs using filtration of cells that have undergone epithelial-mesenchymal transition may improve detection in this subgroup.

Citation Format: Davis AA, Zhang Y, Behdad A, Taxter T, Strickland K, Santa-Maria C, Flaum L, Cruz MR, Platanias LC, Gradishar WJ, Cristofanilli M. The utility and correlation of circulating tumor cells (CTCs) and cell-free circulating tumor DNA (ctDNA) based on HER2 positivity [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-21.

Abstract P2-01-05: Comprehensive analysis of genomic alterations in tumor tissue associated with presence of various subpopulations of circulating tumor cells (CTCs) in primary breast cancer

Background: CTCs play a major role in tumor dissemination and progression, and represent one of the key components of the metastatic cascade. The aim of this study was to identify signaling pathways associated with presence of CTCs in primary breast cancer (PBC) patients using a comprehensive genomics approach.

Methods: This translational study included 78 patients with PBC. CTCs were detected before surgery by quantitative RT-PCR assay for expression of epithelial (EP; CK19) or epithelial-mesenchymal transition (EMT) genes (TWIST1, SNAIL1, SLUG, ZEB1). Total DNA and RNA were extracted, in parallel, from fresh frozen primary tumor and the microRNA and mRNA expression profiles were obtained using Human microRNA Microarray v21.0 and SurePrint G3 Human Gene Expression v3 (Agilent Technologies). Next generation sequencing (NGS) was performed by Illumina Multiplex Sequencing using MiSeq Sequencing Reagent Kit V3.

Results:Mutations in BRCA1/2 genes in tumor tissue were more common in patients with epithelial CTCs (CTC_EP) compared to patients without epithelial CTCs in peripheral blood (23.5% vs. 0%, p = 0.02), while there were no mutations in specific genes associated with CTC with EMT phenotype (CTC_EMT).Further, we identified 90 genes and 7 miRs that were expressed at significantly different levels in tumors with presence of CTC_EP and 199 genes and 13 miRs specifically associated with CTC_EMT, compared to tumors with non-detectable CTCs. We also identified 39 overlapping genes and 7 miRs, that were expressed at significantly different levels in tumors with CTC_EP and/or CTC_EMT compared to tumors with non-detectable CTCs. Overlapping genes and miRs with highest different levels in expression were ATAD3A, TMEM201, DCPS, DOCK9-AS2, TRAF2 and miR-5195-3p, miR-188-5p, miR-6780a-5p, miR-6757-5p. Signalling pathways associated with these genomic alterations belong to several critically functional groups, such as immune response, signal transduction, cell proliferation, cell cycle progression, or apoptosis were significantly differentially based on CTCs status.

Conclusions: We identified for the first time various genomic alterations in primary tumor tissue of PBC associated with different CTCs subpopulations in peripheral blood. We hypothesize that these genomic alterations could play a role in tumor dissemination and progression and might lead to identification of new therapeutic targets.

Citation Format: Mego M, Tokar T, Minarik G, Hajduk M, Karaba M, Benca J, Sedlackova T, Repiska G, Krasnicanova L, Macuch J, Sieberova G, Pindak D, Cristofanilli M, Reuben JM, Jurisica I, Mardiak J. Comprehensive analysis of genomic alterations in tumor tissue associated with presence of various subpopulations of circulating tumor cells (CTCs) in primary breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-01-05.

Abstract GS6-05: Gain-of-function kinase library screen identifies FGFR1 amplification as a mechanism of resistance to antiestrogens and CDK4/6 inhibitors in ER+ breast cancer

Background: CDK4/6 inhibitors have been approved in combination with endocrine therapy for treatment of ER+ metastatic breast cancer. The goal of this study was to discover mechanisms of resistance to ER antagonists alone and in combination with CDK4/6 inhibitors.

Results: To achieve this goal, we used lentiviral vectors to individually express 559 human kinase open reading frames (ORFs) in ER+ MCF7 human breast cancer cells treated with fulvestrant ± the CDK4/6 inhibitor ribociclib. In MCF7 cells treated with fulvestrant alone or with ribociclib, we identified 15 and 17 kinases associated with resistance, respectively. Ten of these kinases overlapped in both groups. In a secondary screen, MCF7 cells were stably transduced with V5-tagged lentiviruses expressing the positive 'hits' for treatment with fulvestrant/ribociclib. Five of 17 kinases (FGFR1, FRK, HCK, FGR, CRKL) were confirmed to induce resistance to fulvestrant/palbociclib and fulvestrant/ribociblib. Survey of TCGA for copy number alterations and/or expression of these 5 genes showed only FGFR1 to be amplified/overexpressed in ˜15% of ER+ breast cancers. Experiments in vitro showed that ER+/FGFR1-amplified (amp) MDA-134, CAMA-1 and HCC1500 human breast cancer cells and MCF7 cells stably transduced with FGFR1 were relatively resistant to estrogen deprivation, fulvestrant and fulvestrant/palbociclib compared to non-FGFR1 amp MCF7 cells. This resistance was abrogated by treatment with the FGFR tyrosine kinase inhibitor (TKI) lucitanib. Treatment with fulvestrant or palbociclib alone modestly delayed growth of ER+/FGFR1-amp breast cancer patient-derived xenografts (PDX) established in nude mice. However, addition of the FGFR TKI erdafitinib to fulvestrant/palbociclib resulted in marked PDX regression in all mice without associated toxicity and a complete cell cycle arrest measured by Ki67. Treatment of FGFR-amp cells with FGF-2 strongly induced CCND1 (cyclin D1) expression. Downregulation of CCND1 with CCND1 RNAi oligonucleotides restored sensitivity of FGFR1-amp cells to fulvestrant/palbociclib, thus phenocopying the effect of FGFR TKIs. Conversely, overexpression of CCND1 in MCF7 cells induced resistance to estrogen deprivation and to fulvestrant ± palbociclib. Finally, we examined next gen sequencing of cell free tumor DNA by Guardant360 in 34 patients before and after progression on CDK4/6 inhibitor. In 10/34 (29%) post-progression specimens, we detected alterations in the FGFR pathway: FGFR1 amplification (n=7), FGFR1 N546K (n=1), FGFR2 N549K (n=1), and FGFR2 V395D (n=1) activating mutations.

Conclusions: These data suggest aberrant FGFR signaling is a mechanism of resistance to anti-ER therapies ± CDK4/6 inhibitors. We posit overexpression of cyclin D1 induced by both FGFR signaling and ER transcription plays a role in drug resistance. Based on these findings we propose ER+/FGFR1 amplified breast cancers are endocrine resistant and should be candidates for treatment with combinations of ER and FGFR antagonists. Accordingly, we have initiated a phase Ib trial of fulvestrant, palbociclib and erdafitinib in patients with antiestrogen resistant ER+/HER2-negative breast cancer with FGFR1-4 amplification.

Citation Format: Formisano L, Lu Y, Jansen VM, Bauer JA, Hanker A, Gonzalez Ericsson P, Lee K-M, Nixon MJ, Guerrero-Zotano AL, Schwarz LJ, Sanders M, Sudhan D, Dugger TC, Cruz MR, Behdad A, Cristofanilli M, Bardia A, O'Shaughnessy J, Mayer IA, Arteaga CL. Gain-of-function kinase library screen identifies FGFR1 amplification as a mechanism of resistance to antiestrogens and CDK4/6 inhibitors in ER+ breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS6-05.

Abstract PD1-02: Circulating tumor DNA (ctDNA): A real-time application of precision medicine to the management of metastatic breast cancer (MBC)

Background: Molecular diagnostic, in particular next-generation sequencing (NGS) technologies, improved the detection of actionable mutations (muts) in MBC at baseline and recurrence. We evaluated the ability of ctDNA to detect molecular abnormalities, monitor disease progression and predict outcome.

Methods: We conducted a retrospective study of 91 patients (pts) with locally advanced and MBC, who had longitudinal assessment of their disease by ctDNA analysis. The plasma-based assay was performed utilizing Guardant360 (Guardant Health, CA), a digital NGS technology to sequence a panel of > 50 cancer genes. After tabulating number of muts and quantification of overall ctDNA detected for every patient at baseline, a receiver operating characteristic (ROC) analysis was performed to identify the best cut-offs that separated the pts who had a disease progression from those who hadn't, and the patients who died from those still alive. The overall survival (OS) analysis has been performed using Kaplan-Meier curves.

Results: 84 pts (92%) had stage IV cancer. 63% cases were ER+, 27% HER2+, 29% TNBC. 277 blood samples were collected and 84% had muts. 65% of the pts had serial samples. The average number of alterations detected in each sample was 3 (0-27) and the average ctDNA fraction detected was 4.5% (0-88.2%). The most common alterations were: TP53 (52%), PIK3CA (40%), ERBB2 (20%), NOTCH1 (15.5%), APC (14%), MET (13%). 16 pts (19%) were initiated on a targeted therapy based on ctDNA test results. At the time of analysis 36 pts (39.6%) were dead, 55 (60.4%) were currently alive. PFS was 5.2 months (ms) and OS was 21.5 ms. A statistically significant difference in PFS and OS by log rank test was found between % ctDNA at baseline < 0.5 versus ≥ 0.5 (p = 0.003 and p = 0.012, respectively) and number of muts at baseline < 2 versus ≥ 2 (p = 0.059 borderline and p = 0.0015). Moreover, a statistically significant association by Fisher's exact test was found between the number of alterations and the % ctDNA detected in the baseline sample (% of pts with muts ≥ 2 was 19% when % ctDNA < 0.5%, versus 85% when % ctDNA ≥ 0.5%; p < 0.0001).

PFS (ms) p = 0.059 (log rank test)Muts < 2 (n = 32)Muts ≥ 2 (n = 58)658%40%1230%13%1821%6%24--PFS(ms) p = 0.003 (log rank test)% ctDNA < 0.5(n = 27)% ctDNA ≥ 0.5(n = 60)665%39%1241%10%1823%6%24--

OS(ms) p = 0.002 (log rank test)Muts < 2(n = 32)Muts ≥ 2(n = 57)697%66%1288%51%1888%42%24-29%OS(ms) p = 0.012 (log rank test)% ctDNA < 0.5(n = 27)% ctDNA ≥ 0.5(n = 59)696%69%1290%55%1885%48%24-35%

Conclusions: ctDNA liquid biopsy provides a real-time, quantitative NGS-based assessment of MBC which is useful for treatment planning, disease monitoring and prognostic evaluation. Future prospective studies should consider the use of ctDNA for molecular and prognostic stratification.

Citation Format: Rossi G, Austin LK, Nagy RJ, Rademaker AW, Gradishar WJ, Santa-Maria CA, Curry-Edwards RL, Jain S, Flaum LE, Lima Barros Costa R, Zagonel V, Platanias LC, Giles FJ, Talasaz A, Cristofanilli M. Circulating tumor DNA (ctDNA): A real-time application of precision medicine to the management of metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD1-02.

Abstract P1-01-05: Prognostic values of circulating tumor cells (CTC) and cancer associated macrophage-like cells (CAML) enumerations in metastatic breast cancer: The role for innate immunity in the metastatic process

Background: The enumeration of circulating tumor cells (CTCs) using the CellSearch assay is a well-established prognostic and predictive marker for metastatic breast cancer (MBC). However, additional prognostic markers are lacking in patients with ≥ 5 CTCs in 7.5 ml of blood. Tumor-associated macrophages (TAMs) are derived from circulating monocytes or tissue-resident macrophages. TAMs have a controversial role in metastasis and anti-tumor processes. Recent studies showed that circulating cancer associated macrophage-like cells (CAMLs) are specialized phagocytic myeloid cells and found in the peripheral blood of patients with solid tumors including breast cancer, but not in healthy individuals. The presence of CAMLs may indicate the activation of innate immunity in cancer patients. The function and prognostic value of CAMLs in MBC is unknown. In the current study, we measured CTCs and CAMLs on the CellSearch™ platform and investigated their prognostic values in MBC.

Methods: Peripheral blood samples from 127 stages IV breast cancer patients were collected at baseline before starting first-line therapy. The detection and enumeration of CTCs and CAMLs in 7.5 ml blood sample were performed on the CellSearch™ system. CTCs were identified by cytokeratins (CK-8, 18, and 19) positive and CD45 negative staining. CAMLs were defined by positive staining for cytokeratins and CD45 (Adams et al, PNAS, 111(9):3514-9, 2014). CTCs and CAMLs enumeration in associations with the progression-free survival (PFS) and overall survival (OS) of patients were evaluated using Kaplan Meier curves and Cox proportional hazards modeling.

Results: The image review of CAMLs by using CellSearch analysis showed heterogeneous morphological phenotypes. CAMLs are large cells presenting enlarged nuclei or multiple individual nuclei, and both cytokeratin and CD45 positive with diffused cytoplasmic staining. Among the 127 MBC patients, 38 (29.9%) had elevated CTCs (≥5 CTCs), and 21 (16.5%) had at least one CAML detected. Patients with CAMLs had a significantly increased PFS (p=0.0374) and OS (p=0.0042), compared to patients without CAMLs at baseline. Patients with elevated baseline CTCs and CAMLs had worse PFS with a hazard ratio (HR) of 4.04 (95% CI 2.16 -7.56, P<0.0001), compared to patients with < 5 CTCs and without CAMLs. The combined analysis of baseline CTCs enumeration and CAMLs showed similar effect on patient OS. Compared to patients with < 5 CTCs and without CAMLs, patients with < 5 CTCs and with CAMLs, patients with ≥ 5 CTCs and without CAMLs, and patients with ≥ 5 CTCs and with CAMLs, had an increasing trend of death risk, with an HR of 2.66 (95% CI 0.53-13.21), 6.14 (2.10-17.92), and 9.13 (3.05-27.37), respectively (p for trend<0.0001).

Conclusion: Baseline enumerations of both individual CTCs and CAMLs are feasible and increase our ability to accurately predict outcome in MBC patients. Evaluation of CAMLs in peripheral blood may be a marker of innate immunity and provide additional prognostic values for MBC.

Citation Format: Mu Z, Wang C, Ye Z, Rossi G, Austin L, Yang H, Cristofanilli M. Prognostic values of circulating tumor cells (CTC) and cancer associated macrophage-like cells (CAML) enumerations in metastatic breast cancer: The role for innate immunity in the metastatic process [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-01-05.

Abstract P1-05-06: Estrogen receptor 1 (ESR1) mutations in circulating tumor DNA (ctDNA): A guide to the management of advanced breast cancer (ABC)

Background: Estrogen receptor (ER)-α is expressed in about 70% of breast cancers and drugs that target the receptor function, selective estrogen receptor modulators (SERM) and aromatase inhibitors (AIs) represent the standard of care for patients (pts) with ER+ breast cancer. Nevertheless, prolonged exposure to endocrine therapy may result in acquired resistance and subsequent progression of disease. Recent evidence showed that activating mutations (muts) in the ligand-binding domain of ER-α occur in approximately 20% of pts exposed to endocrine therapies and those genomic abnormalities may represent the driver of endocrine resistance. In this context, ctDNA provides a non-invasive source for real-time next generation sequencing (NGS) studies, in order to understand the biology of ABC and guide and monitor treatment.

Methods: We conducted a retrospective review of 91 pts with ABC, including 57 pts with ER+ tumor, who had longitudinal assessment of their disease by ctDNA analysis. At the time of baseline sampling, 50/57 pts had stage IV cancer. The total number of blood samples collected was 184. 38 (67%) pts had serial samples. The average number of samples for each pt was 3 (range 1-7). The plasma-based assay was performed utilizing Guardant360 (Guardant Health, CA), a digital NGS technology to sequence a panel of > 50 cancer genes.

Results: Among the ER+ subgroup (57 pts), we identified 11 pts (19%) harboring ESR1 muts in ctDNA. All 11 pts had metastatic disease: 2 (18%) had bone metastases, 2 (18%) had visceral metastases, 7 (64%) had both sites of disease. The median age was 55 years (range 33-73). 5 pts had inflammatory breast cancer. The most common ESR1 muts were: Y537S (6/11, 55%), D538G (4/11, 36%) and Y537N (3/11, 27%). 7 pts carried polyclonal muts. At the time of testing, 10 pts had already failed at least 1 line of endocrine therapy (average 2, range 1-5), including 6 pts that had received a fulvestrant-containing regimen, 8 pts ≥ 1 line of AIs. After the mut detection, 5 pt were on endocrine therapy and 4 pts were started on/continued chemotherapy. ESR1 muts disappeared in 2 pts (fulvestrant-palbociclib and chemotherapy respectively) who achieved stable disease as best response. Three pts continued to harbour muts and then progressed (one died). 2 pts had tissue NGS and ESR1 mut was not identified. Progression free survival and overall survival were 8 months (ms) and 21.5 ms in ESR1+ subpopulation versus 6.2 ms and 22.2 ms in the ESR1- pts (p = 0.78 and p = 0.97, respectively). At the time of analysis 5 pts were dead, 6 were currently alive.

  ESR1+ (n. pts) ESR1- (n. pts) Pts (total n.)1146 Previous chemotherapies11 (100%)31 (67%) Previous fulvestrant-containing regimens6 (54%)20 (43%) Previous AIs ± targeted therapy8 (73%)27 (59%)

Conclusions: We observed that ESR1 muts, a known driver of endocrine resistance, occurs at a high frequency in heavily pre-treated estrogen receptor positive ABC. Blood-based diagnostics can be used to identify ESR1 muts sometimes not detected by tissue-based sequencing of the metastatic lesions indicating tumor heterogeneity and allowing dynamic monitoring of ABC.

Citation Format: Rossi G, Lima Barros Costa R, Nagy RJ, Rademaker AW, Gradishar WJ, Santa-Maria CA, Curry-Edwards RL, Jain S, Flaum LE, Zagonel V, Platanias LC, Giles FJ, Talasaz A, Cristofanilli M. Estrogen receptor 1 (ESR1) mutations in circulating tumor DNA (ctDNA): A guide to the management of advanced breast cancer (ABC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-05-06.

Abstract OT3-01-01: A phase II study of PD-L1 and CTLA-4 inhibition and immunopharmcogenomics in metastatic breast cancer

Background

A hallmark of cancer is its ability to evade the immune system, however, it can be harnessed to detect and destroy cancer cells through inhibition of immune checkpoints such as CTLA-4 and PD-L1. This strategy has complementary and non-redundant mechanisms resulting in immune activation and antitumor synergy; progression free survival benefit has already been demonstrated in melanoma. A critical barrier in developing immunotherapies, however, is the identification of predictive biomarkers of response to therapy. Immunopharmacogenomic biomarkers, such as mutational burden, neoantigen profiles, and T cell receptor sequencing will elucidate the molecular interface between cancer and immune system, and may predict those most likely to benefit.

Methods

A single arm Phase II study was designed to determine the efficacy of PD-L1 and CTLA-4 inhibition and effects on immunopharmacogenomic dynamics in patients with metastatic breast cancer. The primary endpoint of this proposal is to investigate the response rate of the PD-L1 inhibitor, durvalumab, and the CTLA-4 inhibitor, tremelimumab, in metastatic breast cancer; secondary endpoints will examine the T cell receptor repertoire clonality, tumor mutational burden and neoantigen profiles. A total of 30 patients will be enrolled and treated with durvalumab 1500mg IV and tremelimumab 75mg IV monthly for 4 doses, then durvalumab 750mg every 2 weeks for 18 doses to complete 1 year of therapy with the option to renew therapy for an additional year; biopsies and blood at baseline and 2 months will be collected to assess immunopharmacogenomic biomarkers. Patients are eligible if they have triple negative or ER-positive breast cancer and have progressed on at least one line of chemotherapy and standard endocrine therapy if applicable. This is the first study to investigate immunopharmacogenomic biomarkers of response to dual checkpoint blockade in patients with metastatic breast cancer.

Citation Format: Santa-Maria CA, Jain S, Flaum L, Park J-H, Kato T, Gross L, Uthe R, Tellez C, Stein R, Rademaker A, Gradishar WJ, Nakamura Y, Giles FJ, Cristofanilli M. A phase II study of PD-L1 and CTLA-4 inhibition and immunopharmcogenomics in metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-01-01.

Abstract P4-22-07: Long-term safety of palbociclib in combination with endocrine therapy in treatment-naive and previously treated women with HR+ HER2– advanced breast cancer: A pooled analysis from randomized phase 2 and 3 studies

Background: Palbociclib (PAL) is a selective and reversible oral cyclin-dependent kinase 4 and 6 inhibitor. Large randomized phase (ph) 2 and 3 trials showed significant improvement in progression-free survival (PFS) when PAL was combined with endocrine therapy (ET) vs ET alone in treatment (trt)-naive and previously treated hormone receptor?positive human epidermal growth factor receptor 2?negative (HR+ HER2–) advanced breast cancer (ABC) patients (pts). The median PFS with PAL+ET is >2 years as a first-line therapy for ABC and 11.2 mo in endocrine-resistant ABC. We evaluated the long-term safety in PALOMA-1, -2, and -3.

Methods: We analyzed the tolerability of PAL in combination with ET in 3 randomized trials. Pts untreated for ABC were randomized to receive PAL+letrozole (LET) vs LET alone in PALOMA-1 (ph 2, open-label; 1:1) or randomized to receive PAL+LET vs placebo (PBO)+LET in PALOMA-2 (ph 3, double-blind; 2:1). PALOMA-3 included pts who progressed on prior ET, randomized to receive PAL+fulvestrant (FUL) or PBO+FUL (ph 3, double-blind; 2:1). Safety assessments, including a complete blood count, were done at baseline, on D1 of each cycle, and on D14 of the first 2 cycles. We evaluated adverse events (AEs) by 6-mo intervals (out to 36 mo) and cumulatively (12-, 24-, and 36-mo time points), and assessed latency (event onset) of pertinent adverse drug reactions (ADRs) in all pts treated in PALOMA-1, -2, and -3.

Results: A total of 1352 pts were pooled for this analysis; 872 pts received PAL+ET (527 pts, PAL+LET; 345 pts, PAL+FUL). Median duration of trt was 421 days in PALOMA-1 (January 2015), 603 days in PALOMA-2 (February 2016), and 330 days in PALOMA-3 (July 2015). PAL+LET was received by 119 pts as first-line trt in PALOMA-1 and 2 for 24–<30 months and 11 pts were treated for >36 mo. PAL+FUL was received by 140 pts for >12 mo as second-line trt in PALOMA-3. The most commonly reported ADRs across all studies were neutropenia, fatigue, nausea, anemia, and leukopenia. The 6-mo-interval analyses of the most common (>15%) AEs (by preferred term [PT]) from PALOMA-1, -2, and -3 indicated that these AEs were reported with the highest frequency during the first 6-mo interval and typically decreased in incidence over time to 30–<36-mo; the most common hematologic AEs (clustered PTs) are shown (Table). The cumulative incidence of AEs after the first vs the second and third years showed similar frequencies of most AEs, including the most common ADRs.

Conclusions: Based on these long-term safety analyses, there is no evidence of specific cumulative or delayed toxicity resulting from prolonged trt with PAL+ET for HR+ HER2– ABC. This supports the ongoing investigation of PAL+ET in early breast cancer (NCT02513394).

Table. Pooled hematologic AEs: all grades and all causality clustered PTs reported for ≥10% of PAL+ET (LET/FUL)-treated ptsTime interval, mo0–<66–<1212–<1818–<2424–<3030–<36≥36Patients, N8726764912891192711TEAEs, %       Neutropenia75.758.649.349.842.937.054.5Leukopenia40.027.416.711.87.611.118.2Anemia20.812.710.011.19.211.118.2Thrombocytopenia15.18.76.15.55.914.836.4TEAEs=treatment-emergent adverse events.

Sponsor: Pfizer.

Citation Format: Diéras V, Rugo HS, Gelmon K, Finn RS, Cristofanilli M, Loi S, Colleoni M, Lu D, Gauthier E, Huang-Bartlett C, Turner NC, Schnell P. Long-term safety of palbociclib in combination with endocrine therapy in treatment-naive and previously treated women with HR+ HER2– advanced breast cancer: A pooled analysis from randomized phase 2 and 3 studies [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-07.

Developmental therapeutics for patients with breast cancer and central nervous system metastasis: current landscape and future perspectives

Breast cancer is the second-leading cause of metastatic disease in the central nervous system (CNS). Recent advances in the biological understanding of breast cancer have facilitated an unprecedented increase of survival in a subset of patients presenting with metastatic breast cancer. Patients with HER2 positive (HER2+) or triple negative breast cancer are at highest risk of developing CNS metastasis, and typically experience a poor prognosis despite treatment with local and systemic therapies. Among the obstacles ahead in the realm of developmental therapeutics for breast cancer CNS metastasis is the improvement of our knowledge on its biological nuances and on the interaction of the blood–brain barrier with new compounds. This article reviews recent discoveries related to the underlying biology of breast cancer brain metastases, clinical progress to date and suggests rational approaches for investigational therapies.

Transglutaminase-6 is an autoantigen in progressive multiple sclerosis and is upregulated in reactive astrocytes

BACKGROUND

Transglutaminase-6 (TGM6), a member of the transglutaminase enzyme family, is found predominantly in central nervous system (CNS) neurons under physiological conditions. It has been proposed as an autoimmune target in cerebral palsy, gluten-sensitive cerebellar ataxia, and schizophrenia.

OBJECTIVE

To investigate TGM6 involvement in multiple sclerosis (MS).

METHODS

Antibody levels against TGM6 (TGM6-IgG) were measured in the cerebrospinal fluid (CSF) of 62 primary progressive multiple sclerosis (PPMS), 85 secondary progressive multiple sclerosis (SPMS), and 50 relapsing-remitting multiple sclerosis (RRMS) patients and 51 controls. TGM6 protein expression was analyzed in MS brain autopsy, murine experimental autoimmune encephalomyelitis (EAE), and cultured astrocytes.

RESULTS

CSF levels of TGM6-IgG were significantly higher in PPMS and SPMS compared to RRMS and controls. Notably, patients with clinically active disease had the highest TGM6-IgG levels. Additionally, brain pathology revealed strong TGM6 expression by reactive astrocytes within MS plaques. In EAE, TGM6 expression in the spinal cord correlated with disease course and localized in reactive astrocytes infiltrating white matter lesions. Finally, knocking down TGM6 expression in cultured reactive astrocytes reduced their glial fibrillary acidic protein (GFAP) expression.

CONCLUSION

TGM6-IgG may be a candidate CSF biomarker to predict and monitor disease activity in progressive MS patients. Furthermore, TGM6 expression by reactive astrocytes within both human and mouse lesions suggests its involvement in the mechanisms of glial scar formation.

Circulating Tumor Cells (CTC) Are Associated with Defects in Adaptive Immunity in Patients with Inflammatory Breast Cancer

Background: Circulating tumor cells (CTCs) play a crucial role in tumor dissemination and are prognostic in primary and metastatic breast cancer. Peripheral blood (PB) immune cells contribute to an unfavorable microenvironment for CTC survival. This study aimed to correlate CTCs with the PB T-cell immunophenotypes and functions of patients with inflammatory breast cancer (IBC).

Methods: This study included 65 IBC patients treated at the MD Anderson Cancer Center. PB was obtained from patients prior to starting a new line of chemotherapy for CTCs enumeration by CellSearch^®, and T cell phenotype and function by flow cytometry; the results were correlated with CTCs and clinical outcome.

Results: At least 1 CTC (≥1) or ≥5 CTCs was detected in 61.5% or 32.3% of patients, respectively. CTC count did not correlate with total lymphocytes; however, patients with ≥1 CTC or ≥5 CTCs had lower percentages (%) of CD3+ and CD4+ T cells compared with patients with no CTCs or <5 CTCs, respectively. Patients with ≥1 CTC had a lower percentage of T-cell receptor (TCR)-activated CD8+ T cells synthesizing TNF-α and IFN-γ and a higher percentage of T-regulatory lymphocytes compared to patients without CTCs. In multivariate analysis, tumor grade and % CD3+ T-cells were associated with ≥1 CTC, whereas ≥5 CTC was associated with tumor grade, stage, % CD3+ and % CD4+ T cells, and % TCR-activated CD8 T-cells synthesizing IL-17.

Conclusions: IBC patients with CTCs in PB had abnormalities in adaptive immunity that could potentially impact tumor cell dissemination and initiation of the metastatic cascade.

Quality of life with palbociclib plus fulvestrant in previously treated hormone receptor-positive, HER2-negative metastatic breast cancer: patient-reported outcomes from the PALOMA-3 trial

In treating HR+, HER2− metastatic breast cancer, novel agents that enhance endocrine therapy activity but do not worsen quality of life (QoL) are clinically desired. Patient-reported outcomes data from the PALOMA-3 study suggest palbociclib plus fulvestrant allow patients to maintain good QoL in the endocrine resistance setting while experiencing a substantially delayed disease progression.

Background

In the PALOMA-3 study, palbociclib plus fulvestrant demonstrated improved progression-free survival compared with fulvestrant plus placebo in hormone receptor-positive, HER2− endocrine-resistant metastatic breast cancer (MBC). This analysis compared patient-reported outcomes (PROs) between the two treatment groups.

Patients and methods

Patients were randomized 2 : 1 to receive palbociclib 125 mg/day orally for 3 weeks followed by 1 week off (n = 347) plus fulvestrant (500 mg i.m. per standard of care) or placebo plus fulvestrant (n = 174). PROs were assessed on day 1 of cycles 1–4 and of every other subsequent cycle starting with cycle 6 using the EORTC QLQ-C30 and its breast cancer module, QLQ-BR23. High scores (range 0–100) could indicate better functioning/quality of life (QoL) or worse symptom severity. Repeated-measures mixed-effect analyses were carried out to compare on-treatment overall scores and changes from baseline between treatment groups while controlling for baseline. Between-group comparisons of time to deterioration in global QoL and pain were made using an unstratified log-rank test and Cox proportional hazards model.

Results

Questionnaire completion rates were high at baseline and during treatment (from baseline to cycle 14, ≥95.8% in each group completed ≥1 question on the EORTC QLQ-C30). On treatment, estimated overall global QoL scores significantly favored the palbociclib plus fulvestrant group [66.1, 95% confidence interval (CI) 64.5–67.7 versus 63.0, 95% CI 60.6–65.3; P = 0.0313]. Significantly greater improvement from baseline in pain was also observed in this group (−3.3, 95% CI −5.1 to −1.5 versus 2.0, 95% CI −0.6 to 4.6; P = 0.0011). No significant differences were observed for other QLQ-BR23 functioning domains, breast or arm symptoms. Treatment with palbociclib plus fulvestrant significantly delayed deterioration in global QoL (P < 0.025) and pain (P < 0.001) compared with fulvestrant alone.

Conclusion

Palbociclib plus fulvestrant allowed patients to maintain good QoL in the endocrine resistance setting while experiencing substantially delayed disease progression.

Clinical Trial Registration

NCT01942135.

CXCR4-SDF-1 interaction potentially mediates trafficking of circulating tumor cells in primary breast cancer

Background

Cytokines are involved in cancer invasion and metastasis. Circulating tumor cells (CTCs) play key role in tumor dissemination and are an independent survival predictor in breast cancer patients. The aim of this study was to assess correlation between CTCs and plasma cytokines in primary breast cancer (PBC) patients.

Methods

This study included 147 chemotherapy naïve PBC patients. Peripheral blood mononuclear cells (PBMC) were depleted of hematopoetic cells using RossetteSep™ negative selection kit. RNA extracted from CD45-depleted PBMC was interrogated for expression of EMT (Twist1, Snail1, Slug, Zeb1) and epithelial (Ck19) gene transcripts by qRT-PCR. The concentrations of 51 plasma cytokines were measured using multiplex bead arrays.

Results

CTCs were detected in 25.2 % patients. CTCs exhibiting only epithelial markers (CTC_EP) and only EMT markers (CTC_EMT) were present evenly in 11.6 % patients, while CTCs co-expressing both markers were detected in 2.0 % patients. Patients with presence of CTC_EP in peripheral blood had significantly elevated levels of plasma IFN-α2, IL-3, MCP-3, β-NGF, SCF, SCGF-β, TNF-β and SDF-1 compared to patients without CTC_EP. CTC_EP exhibited overexpression of SDF-1 receptor and CXCR4, but not other corresponding cytokine receptor, and in multivariate analysis SDF-1 was independently associated with CTC_EP. There was an inverse correlation between CTC_EMT and plasma cytokines CTACK, β-NGF and TRAIL, while presence of either subtype of CTCs was associated with increased level of TGF-β2.

Conclusion

Using cytokine profiling, we identified cytokines associated with CTCs subpopulations in peripheral blood of PBC. Our data suggest that CXCR4-SDF-1 axis is involved in mobilization and trafficking of epithelial CTCs.

Abstract P6-18-01: Novel genetic susceptibility loci for inflammatory breast cancer identified by whole exome sequencing

Background: Inflammatory breast cancer (IBC) is an extremely aggressive form of locally advanced breast cancer that affects approximately 5% of breast cancer patients. The prognosis of IBC patients is remarkably poor, with a three-year survival rate of approximately 30% compared to 60% for non-IBC breast cancer patients. The etiology of IBC is largely unknown. A few risk factors have been reported such as body mass index (BMI) and educational level. Prior evidence has also implicated genetic components in IBC etiology. For instance, the reported familial cases and racial incidence disparity of IBC patients, as well as the fact IBC patients typically have a younger age onset than non-IBC patients, all indicated the possible involvement of genetic factors. Nevertheless, as yet no genetic epidemiological study has been reported to evaluate IBC genetic predisposition.

Methods: To test the hypothesis that genetic variants and mutations may affect IBC susceptibility, we performed whole exome sequencing in a pilot case-control study that contained 70 IBC cases and 119 unrelated cancer-free controls. Sequencing data were de-multiplexed, filtered, assessed for various quality control metrics, mapped to reference genome and annotated. Comprehensive single variant-based, gene-centered, and pathway-based analyses were conducted to identify variants, genes, and pathways that may be involved in IBC predisposition.

Results: We obtained &gt; 50x on-target sequencing coverage of the whole exome in &gt; 90% of the patients. In single variant analysis, we identified six variants reaching genome-wide significance. Four variants were encoded by genes that have been implicated in breast cancer development including MALAT1, MAP3K9, POLR3B, and FIP1L1. Two variants were encoded by novel genes that have not been related to breast cancer, including CCDC30 and LINC01565. Two types of analyses based on a gene-centered strategy identified top genes such as SLC39A4, CDHR1, AP5Z1, GNB3, ITGA10, etc. However, possibly due to the limited sample size, none of these genes reached genome-wide significance. Ingenuity Pathway Analysis (IPA), using the complete list of significant genes identified by each of these analyses all reported "cancer" as the highest possible disorder associated with these genes, demonstrating the biological plausibility of our findings. Moreover, canonical pathways such as IL4 signaling, glycogen degradation, epithelial adherence junction signaling, and CCR3 signaling in eosinophils were among the top pathways that were found involved in IBC predisposition.

Conclusion: Overall, we provided novel preliminary evidence that genetic variants are potentially associated with the risk of developing IBC. We are currently conducting validation studies with larger sample sizes are warranted to confirm these findings and identify additional genetic susceptibility loci.

Citation Format: Ye Z, Li B, Wang C, Zhong X, Wei Q, Mu Z, Austin L, Jaslow R, Avery T, Palazzo J, Biederman L, Yang H, Cristofanilli M, IBC Inflammatory Breast Cancer International Consortium. Novel genetic susceptibility loci for inflammatory breast cancer identified by whole exome sequencing. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-18-01.

Abstract P4-13-03: Updated safety from a double-blind phase 3 trial (PALOMA-3) of fulvestrant with placebo or with palbociclib in pre- and postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer that progressed on prior endocrine therapy

Background: Endocrine therapy (ET) resistance remains a major clinical problem for patients (pts) with hormone receptor (HR+) breast cancer (BC). In PALOMA-3, palbociclib (P) combined with fulvestrant (F) demonstrated significant prolongation of progression-free survival (PFS) vs F plus placebo (PLB) in pre/peri and postmenopausal women with HR+/HER2– metastatic BC (MBC) whose disease progressed on prior ET (median PFS 9.2 vs 3.8 m; HR=0.422, P=0.0001).

Methods: In this double-blind phase 3 study, 521 pts with HR+/HER2– MBC were randomized 2:1 to receive P (125 mg/d orally for 3 weeks followed by 1 week off) and F (500 mg given per standard of care) or PLB plus F. Pre- and perimenopausal women also received goserelin. One previous line of chemotherapy (CT) for MBC was allowed. Safety assessments occurred at baseline and D1 of each cycle; blood counts occurred every 2 wks for the first 2 cycles and on D1 of subsequent cycles. As pts may have experienced multiple episodes of neutropenia during treatment, we analyzed all episodes in aggregate based on laboratory data per CTCAE4.0.

Results: The results reported here are from the data cutoff of Dec 2014, with a median follow-up of 5.6 m. Overall rate of any grade (G) and G3/4 AEs was 98/70% of pts in P+F vs 89/18% in PLB+F. The most commonly reported AEs in P+F (≥20%) were hematologic toxicities, fatigue, nausea, and headache. Per lab data, G3/G4 neutropenia occurred in 52.2/8.2%, G3/G4 leukopenia in 39.5/1.2%, G3/G4 anemia in 20.8/2.9% and G3/G4 thrombocytopenia in 2.1/1.2% of pts on P+F. Neutropenia occurred early, with a median onset time for first episode of ≥G3 neutropenia of 15 d (13–197) and median time from first dose to the lowest absolute neutrophil count (ANC) of 29 d (13–334). The median duration of ≥G3 episode was 7 d (1–35), suggesting that most pts can resume treatment after a 1-week cycle delay. A comparable proportion of any grade neutropenia was observed in pts with or without prior CT (prior CT 88.4% vs no prior CT 85.4%). There was no difference in the rate of G3/G4 neutropenia in the older pts (&gt;65 yrs, 51% vs ≤65 yrs, 57%) in P+F arm. Concurrent G≥3 infections occurred in 1% of pts with G≥3 neutropenia (2/192 pts). Febrile neutropenia occurred in 0.6% of pts in both arms. 21% of pts had dose reductions and 45% had dose interruption due to neutropenia. Dose intensity was maintained at 89.7% for P. Serious adverse events (SAEs) were reported in 9.6% of pts on P+F and in 14% of pts on PLB+F. The most common SAEs on P+F were pulmonary embolism (0.9%) and pyrexia (0.9%). Safety analyses with longer follow-up (data cut off, March 2015) are ongoing and will be presented.

Conclusions: Findings suggest P+F has a favorable safety profile characterized mainly by asymptomatic hematologic toxicity. Overall SAE rates were low and comparable between the 2 arms. Palbociclib-related neutropenia differs from that seen with CT, consistent with proposed mechanism of action, in that it is not commonly associated with fever, and can be effectively managed by a dose interruption or cycle delay.

Funding: Pfizer, Inc.

Citation Format: Verma S, DeMichele AM, Loi S, Ro J, Colleoni M, Iwata H, Harbeck N, Stearns V, Cristofanilli M, Huang Bartlett C, Schnell P, Zhang K, Thiele A, Turner NC, Rugo HS. Updated safety from a double-blind phase 3 trial (PALOMA-3) of fulvestrant with placebo or with palbociclib in pre- and postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer that progressed on prior endocrine therapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-03.

Abstract P4-13-18: A phase I study of romidepsin in combination with nab-paclitaxel in patients with metastatic HER-2 negative inflammatory breast cancer (IBC)

Inflammatory breast carcinoma (IBC) is the most aggressive form of breast cancer. The hallmark of IBC is regional extension into dermal lymphatics as tumor emboli causing breast edema and erythema. Pathologic characteristics of IBC include high grade, negative hormone receptor status and overexpression of HER2 and E-cadherin. The latter is the most attractive therapeutic target in IBC. In preclinical studies the histone deacetylase inhibitor, romidepsin targeted E-cadherin, affecting tumor emboli and increasing taxane sensitivity.

Rationale: In vitro studies show that histone deacetylase inhibitors (HDACi) with taxanes provide synergy to enhance cell death. HDACi alter expression of AIRH1, a regulator of autophagy, typically silenced in breast cancer. In vitro treatment with HDACi induces expression of AIRH1, resulting in enhanced cell death with taxanes. In vitro studies of IBC have demonstrated the utility of HDACi and romidepsin in IBC cell lines. SAHA and romidespin, HDACis, inhibited self-renewal of IBC tumor spheroids from IBC cell lines. This trial combines romidepsin with a taxane proven in metastatic breast cancer to explore whether the combination will be effective in IBC.

Design: This is a phase I trial to assess the safety of romidepsin plus nab-paclitaxel in patients with recurrent or metastatic IBC. The maximum tolerated dose (MTD) of romidepsin + weekly nab-paclitaxel was determined to define the dose for the phase II trial. Secondary objectives included describing the adverse event profile and assessing the overall response rate (ORR) and Clinical Benefit Rate (CBR). This study employed a 3+3 design. DLTs included febrile neutropenia or non-hematologic grade 3 or 4 toxicities. Patients were treated with nab-paclitaxel 100 mg/m2 iv with romidepsin, 7 mg/m2 iv (1st cohort) and 10 mg/m2 iv (2nd cohort), on days 1, 8, 15 of a 28 day cycle.

Results: Nine patients were treated. The median age was 52. Three patients were treated in the first cohort. Two patients showed progressive disease (PD). One patient has had stable disease (SD) over 10 cycles and continues treatment. DLT was not reached at 7 mg. Toxicities related to romidepsin included neutropenia, anemia and fatigue. Six patients were treated in the 2nd cohort. Grade 3 hypophosphatemia, a DLT, was reached. One patient had complete response (CR). One patient had SD; four patients had PD. Toxicities related to romidepsin were anemia, neutropenia, GI upset, edema, hyperglycemia, fatigue, hypophosphatemia, pruritis, dry mouth, and increased lab values. The overall response rate (ORR) was 33% (3/9). The table below shows results.

CohortResponse# Prior TherapiesMetastatic Sites# Cycles on study1PD2pleura, nodes51PD0lung31SD2lung, nodes102PD2pleura, nodes, soft tissue42PD0liver, nodes, bone22CR2 chemotherapy, 2 endocrinebone, nodes72SD0nodes52PD0lung,liver, nodes22PD0liver, bone, nodes2

Conclusions: This phase I trial shows that romidepsin and nab-paclitaxel are well-tolerated in patients with advanced IBC. The MTD and recommended dose of romidepsin is 10 mg/m2 with nab-paclitaxel 100 mg/ m2 days 1, 8, 15 of a 28 day cycle. A phase II trial is planned in recurrent HER negative IBC patients.

Citation Format: Avery TP, Jaslow R, Basu-Mallick A, Zibelli A, Fellin F, Cristofanilli M. A phase I study of romidepsin in combination with nab-paclitaxel in patients with metastatic HER-2 negative inflammatory breast cancer (IBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-18.

Abstract P6-05-07: Improving personalized management of primary breast cancer: Mammaprint® risk stratification and blueprint® molecular subtyping

Background:

Historically, breast cancer (BC) patients were offered cytotoxic or endocrine therapy based on factors such as tumor size, stage, and immunohistochemistry (IHC) markers for estrogen receptor (ER) and HER2-positivity. In 2010 the College of American Pathologists revised the breast cancer guidelines on endocrine therapy (ET) to include a lower threshold of ER positivity by immunohistochemistry, changing the definition from 10% to 1% [Hammond et al]. As a result, although a larger number of patients are offered ET, not all may benefit from this expanded definition of ER positivity if their disease is not truly estrogen driven. More recently, sensitive gene profiling assays, such as Blueprint®, can determine intrinsic molecular subtype which may be more sensitive in predicting which patients will benefit from ET. Additionally, Mammaprint® provides risk stratification which can aid in determining which patients could benefit from neoadjuvant therapy.

Methods

This is an observational analysis of 60 patients with stage I-IV BC. Tissue analysis for ER, PR and HER2 status were determined by IHC/FISH. mRNA expression profiles of 80 genes for Blueprint® (Agendia) analysis provided molecular subtyping: luminal, basal or her2. Moreover, Mammaprint® (Agendia) analysis of 70 genes subdivided patients into low risk or high risk providing further stratification for Luminal-type.

Results

By IHC staining, 48% of patients were ER+/HER2-, 10% were ER+/HER2+, 8.3% were ER-/HER2+, and the remaining patients (20%) were triple negative (TN) BC. By comparison, molecular profiling classified 21% as luminal A, 18% luminal B, 11.6% Her2 and 35% basal subtype. The 35 ER+ patients were heterogeneous by subtype: 13 were classified as molecular luminal A, 16 were luminal B, 4 were reclassified as HER2 and 2 were basal-like (one of whom had 40% ER positivity). Of the ER+ patients whose IHC quantitative staining was known, 29% with low positivity (less than 10%) were reclassified as basal subtype. Of the 5 patients who are ER+/HER2+, 2 were luminal B and 3 were of the HER2-subtype. Two patients who were TN were reclassified as luminal B, and an ER-/HER2+ was classified as a basal subtype. One patient with ER+/HER2- disease had evidence of both HER2 and luminal B subtype. Of the patients who received neo-adjuvant therapy, pCR was obtained in 33% of luminal, 60% of HER2 and 50% of basal-type patients.

Conclusions

BluePrint® and Mammaprint® Molecular profiling are useful diagnostic tools which further characterize tumors to predict risk of recurrence and response to treatment. About one third of ER+ patients with low positivity (less than 10%) were reclassified as basal subtype, suggesting that there is a proportion of patients who are exposed to the morbidity of hormonal therapy with little therapeutic benefit. Additionally, the test is predictive of pCR, with the highest rates in the basal and Her2 subtypes, thus enabling clinicians to predict and improve clinical outcomes through more personalized treatment decisions.

Citation Format: Mikkilineni L, Austin LK, Limentani K, Jaslow RJ, Avery TP, Palazzo J, Cristofanilli M. Improving personalized management of primary breast cancer: Mammaprint® risk stratification and blueprint® molecular subtyping. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-05-07.

Abstract P2-08-09: Prognostic values of circulating tumor cell (CTC) enumeration and their clusters in advanced breast cancer

Background The enumeration of circulating tumor cells (CTCs) has been proven to have prognostic values in several solid tumors including breast cancer. It has been established that a cut-off of 5 CTCs in 7.5 ml of blood may significantly differentiate breast cancer patients with favorable and unfavorable survival. However, CTC enumeration has not been shown to further predict the prognosis in those patients with more than 5 CTCs in 7.5 ml of blood. There are several recent in vitro and in vivo studies suggesting that clusters of CTC can be identified in blood and those clusters may play an important role in tumor progression and metastasis. Few clinical studies have been reported to enumerate CTC clusters and evaluate their prognostic values. In the current study, we hypothesize that the enumeration of CTC clusters play an important role in the prognostication of advanced breast cancer patients by providing additional predictive performance independent of CTC enumeration.

Methods In an ongoing study of blood-based breast cancer biomarkers, we enrolled 114 patients with stages III and IV breast cancer. Among them, 68 patients had inflammatory breast cancer (IBC), an extremely aggressive form of breast cancer with a much lower survival rate than non-IBC breast cancer patients. The number of single CTCs and CTC clusters (two or more CTCs bound together) in 7.5 ml blood sample were counted using the CellSearch™ system (Janssen Diagnostic) at baseline study entry, and their associations with the progression-free survival (PFS) of patients were evaluated using Kaplan Meier curves and Cox proportional hazards modeling.

Results Baseline CTCs were detected in 67 (58.77%) patients. Thirty-five (30.70%) and 19 patients (16.67%) had elevated CTCs (≥5 CTCs/7.5 mL) and clusters, respectively. IBC patients had a slightly higher percentage of cluster (17.65%) compared to non-IBC patients (15.22%). Patients with elevated baseline CTC and cluster had worse PFS (log rank P, 0.0009 and 0.0035, respectively). Compared to patients with &lt; 5 CTC and without cluster, those patients with elevated CTC without cluster, and those with elevated CTC with cluster had an increasingly higher risk of disease progression with an hazard ratio [HR] of 1.93 (95% confidence interval [CI] 1.01-3.67) and 2.91 (1.54-5.50), respectively (P for trend = 0.001). Moreover, the combined analysis of baseline CTC and cluster enumerations showed similar effect when the analysis was restricted to IBC patients (HR 3.03, 95% CI 1.34-6.86).

Conclusion Baseline enumerations of both individual CTCs and CTC clusters predict PFS in advanced stage breast cancer patients. CTC clusters provide further prognostic value in patients with elevated CTC and their molecular characterizations may provide novel insights into the metastasis process.

Citation Format: Ye Z, Mu Z, Wang C, Palazzo JP, Biederman L, Li B, Jaslow R, Avery T, Austin L, Yang H, Cristofanilli M. Prognostic values of circulating tumor cell (CTC) enumeration and their clusters in advanced breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-09.

Abstract P3-05-02: Detection of activating estrogen receptor 1 (ESR1) in circulating tumor DNA (ctDNA) in hormone-receptor positive metastatic breast cancer (MBC)

Background

About 65% of breast cancers express the estrogen receptor α and the mainstay of treatment are therapies that result in estrogen receptor modulation (selective estrogen receptor modulators, SERMs) or estrogen deprivation (aromatase inhibitors, AIs). Even though endocrine therapy has resulted in reduced recurrence and mortality, a significant portion of patients relapse with metastatic disease and subsequently progress while on therapy for advanced disease (endocrine resistance). Recent evidence showed that activating hot spot mutations in the ligand binding domain of the ERα (ESR1) are acquired on treatment (frequency of 20%) and can drive resistance to endocrine therapy, especially AIs. ESR1 mutations can be detected by evaluation of circulating tumor DNA (ctDNA), a method where circulating DNA fragments with tumor-specific sequence alterations are identified in the blood of patients.

Methods

This is a retrospective evaluation of 9 patients with hormone receptor positive (HR+) metastatic breast cancer (MBC) who had progressed on multiple lines of endocrine therapy (ET) and were found to have ESR1 mutations in ctDNA. Patients had blood drawn for ctDNA analysis either at progression to serve as a baseline before starting a new regimen or to monitor response to ongoing treatment. Guardant360™(Guardant Health) involves ctDNA isolation from plasma using a Qiagen circulating nucleic acid kit, then a panel of 68 gene mutations associated with solid tumors as reported in the COSMIC database sequenced using single-molecule digital sequencing technology.

Results

All of the patients had MBC and were luminal subtype except for one HER2+, and most had invasive ductal carcinoma although 2 patients were invasive lobular carcinoma (22%). Most patients had both bone and visceral involvement (78%), only two patients had bone only metastasis. The patients were generally heavily pretreated with an average of 3 lines of ETs and 6 lines of therapy altogether (chemotherapy + ET). Duration on endocrine therapy ranged from 23 months to 7 years (mean 4.3 years). All patients were found to have ESR1 mutations on ctDNA, the range of percentage of mutant allele was 0.28-23.76%. Three patients had tissue sent for NGS and none of the tissue samples had an ESR1 mutation detected although they were biopsied at various time points in treatment. One of those patients had two ESR1 mutations in ctDNA, which were not detected on tissue sent for NGS one year prior, and had not been on ET for several years. One patient with abdominal carcinomatosis from lobular carcinoma who had been on ETs therapies for 6 years was found to have 4 distinct ESR1 mutations in a single blood draw, suggesting sub-clonal evolution of resistance. One patient also had 5 circulating tumor cells, all of which had ESR1 mutations detected when circulating tumor cells were individually sequenced.

Conclusions

ctDNA is a sensitive test for detection of ESR1 in HR+ MBC patients, with the advantage of being a blood based assay which lends itself to serial analysis. In this patient population ctDNA can be a helpful tool to predict response to ET and predict treatment failure.

Citation Format: Austin L, Rodriguez A, Jaslow R, Fortina P, Nagy R, Zill O, Talasaz A, Cristofanilli M. Detection of activating estrogen receptor 1 (ESR1) in circulating tumor DNA (ctDNA) in hormone-receptor positive metastatic breast cancer (MBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-05-02.

Abstract OT1-03-07: A randomized, placebo-controlled phase 2 study of paclitaxel in combination with reparixin compared to paclitaxel alone as front-line therapy for triple-negative breast cancer (fRida)

Background: Breast cancer stem cells (BCSC) have the ability to self renew and generate the full range of cells that make up a bulk tumor. Experimental models and retrospective clinical observations point to BCSC as responsible for tumor recurrence and metastasis. CXCR1, one of the receptors for CXCL8, has been identified on BCSC. Reparixin, an allosteric inhibitor of CXCR1, reduced BCSC in breast cancer xenografts (Ginestier C et al., JCI 2010) both as single agent and in combination with taxane chemotherapy. In a phase Ib trial in women with metastatic HER2-negative BC, the combination of escalating doses (400 to 1200 mg three times per day) of reparixin with weekly paclitaxel resulted in a low incidence and severity of adverse reactions, a sizeable response rate and time-to-progression, with some long-term responders (Schott AF et al., SABC 2014).

Trial Design: In this randomized, double-blind phase 2 trial patients will be randomized (1:1) to paclitaxel 80 mg/m2 on days 1, 8 and 15 of 28-day cycles in combination with reparixin or placebo oral tablets 1200 mg three times daily on days 1-21. Treatment continues until disease progression, unacceptable toxicity or withdrawal of consent. An independent Data Monitoring Committee has been appointed to oversee the trial. An independent Radiology Review will be performed for analysis of primary and secondary endpoints. Disease response will be assessed every 8 weeks. Patients will be followed up to 12 months after last enrolled patient completes treatment.

Eligibility Criteria: Patients must be female aged ≥18 years with untreated metastatic TNBC who have relapsed &gt;12 and &gt;6 months after the end of a taxane- or non taxane-based (neo)adjuvant chemotherapy regimen, respectively. They must have measurable disease, ECOG PS of 0-1, adequate organ function, and no history or evidence of brain metastases (brain CT or MRI required). Tumor tissue must be available from a metastatic site or from primary tumor for confirmation of diagnosis and correlative studies. Key exclusion criteria are pre-existing peripheral neuropathy G&gt;1 and any disease significantly affecting gastrointestinal function.

Specific Aims: Primary: to evaluate progression-free survival (PFS) rate by independent assessment.

Secondary: to determine median PFS, overall survival (OS), objective response rates and safety of the combination treatment.

Exploratory: to determine median time to new tumor metastasis (TTM), proportion of patients progressing with new metastatic lesions, incidence and severity of peripheral neuropathy, and to evaluate BCSC in metastatic tissue

Statistical Methods: The trial design provides 80% power to detect an increase in 6 month PFS from 30% to 50% with a 2-sided 5% significance level (Chi-square test). Kaplan-Meier curves will be produced for median PFS, OS outcomes and exploratory median TTM. Appropriate descriptive statistics will be provided for safety variables.

Present Accrual and Target Accrual: Target accrual is 190 patients. Patients will be enrolled internationally in US and Europe.

Contact Information: info@dompe.com

Citation Format: Chang JC, Schott AF, Wicha MS, Cristofanilli M, Ruffini PA, McCanna S, Goldstein LJ. A randomized, placebo-controlled phase 2 study of paclitaxel in combination with reparixin compared to paclitaxel alone as front-line therapy for triple-negative breast cancer (fRida). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-07.

Abstract P2-02-14: Detection and characterization of CTCs isolated by ScreenCell®-Filtration in metastatic breast cancer

Background: Circulating Tumor cells (CTCs) detection has prognostic and predictive implications in patients with metastatic breast cancer (MBC). Genomic and phenotypic analysis of CTCs hold enormous promise as blood-based molecular characterization and monitoring disease progression and treatment benefit with a strong potential to be translated into more individualized targeted treatments. FDA-approved CellSearch™ detection allows only enumeration of CTCs expressing EpCAM without molecular characterization. CTCs represent very heterogeneous populations of tumorigenic cancer cells and some subpopulations have undergone epithelial-Mesenchymal transition (EMT), which is associated metastasis process and an unfavourable outcome. EpCAM-based enrichment technique has failed to detect EMT subpopulations due to the decreased expression or loss of epithelial markers. Non-EpCAM-based approaches are needed for identifying EMT CTCs. The ScreenCell® devices are single-use and low-cost innovative devices that use a filter for enrichment-free isolation of CTCs by a two-steps combining size-based separation and staining using different markers. The DEPArray™ system is the ideal downstream isolation system to collect single or pooled CTCs for molecular and genetic analysis. In this study, we evaluated the feasibility of achieving CTCs detection/enumeration using ScreenCell® filtration followed by single cell isolation with the DEPArray™ in MBC patients.

Methods: The first part of the study consisted in evaluating CTCs detection/enumeration in 30 patients with stage III and stage IV breast cancer. 3 mL of whole blood in an EDTA or Transfix tubes was collected and processed on the ScreenCell® Cyto device following the instructions of the supplier. CTCs were stained with cytokeratin (CK-8, 18, and 19), leukocyte antigen (CD45), and a nuclear dye (DAPI) and counted under fluorescence microscope. CTCs were identified as positive staining for CK and DAPI and negative staining for CD45 (CK+/DAPI+CD45-). In the second part, After enrichment, CTCs were stained with CK, CD45, and DAPI and sorted with DEPArray™ Platform (Silicon Biosystems, Inc). Single CTCs were collected and the DNA of each single CTCs was amplified with Ampli1™ WGA kit, and the genome integrity index (GII) was assessed by Ampli1™ QC kit (Silicon Biosystems, Inc). Library was constructed and whole exome sequencing (WES) of DNA mutations was conducted.

Results: Twenty patient samples had CTCs detected (66.7%), the number of CTCs was 1 to 347 per 3.0 ml of whole blood. CTC-clusters were detected in 7 patient samples (23.3%). Single CTCs were collected on DEPArray™ platform after enrichment with ScreenCell filtration. GII was confirmed with the presence of short, medium, and long DNA fragments (3 to 4 PCR bands) in the WGA library by PCR-based assay. All collected CTCs showed high GII as measured by Ampli1™ QC kit (GII ≥ 3) for WES of DNA mutations. The data analysis of WES results is under processing.

Conclusions: ScreenCell® filtration is simple and effective devices to isolate CTCs and identify CTC-clusters. Isolation of single cells for molecular analysis using the combination of ScreenCell® filtration and DEPArray™ Platform is feasible for genetic characterization of CTCs.

Citation Format: Mu Z, Benali-Furet N, Uzan G, Ye Z, Austin L, Wang C, Nguyen1 T, Avery T, Jaslow R, Yang H, Cristofanilli M. Detection and characterization of CTCs isolated by ScreenCell®-Filtration in metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-14.

Abstract P4-13-01: PALOMA3: Phase 3 trial of fulvestrant with or without palbociclib in pre- and postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer that progressed on prior endocrine therapy—confirmed efficacy and safety

Background: Selective estrogen receptor modulators and aromatase inhibitors (AI) (+LHRH agonists [premenopausal]) are standard of care (SOC) for hormone–receptor–positive (HR+) metastatic breast cancer (MBC). Many HR+ MBC patients (pts) get limited benefit from adjuvant or advanced endocrine therapy (ET) and develop endocrine resistance, refractory disease. HR+ BC growth relies on cyclin dependent kinases 4/6 that promote G1–S phase cell cycle progression. Palbociclib (PAL) with ET showed efficacy in HR+/HER2– MBC (Turner et al, 2015). We report updated safety and efficacy from PALOMA3 with longer follow–up, focusing on degrees of clinically defined endocrine resistance.

Methods: Pts with HR+/HER2– MBC that progressed on prior ET were randomized 2:1 to PAL (125 mg/d oral [3 wks drug, 1 wk off]) + fulvestrant (F, 500 mg, SOC) +/– goserelin or placebo (PLB)+F. One line of chemotherapy (CT) for MBC was allowed. Pt stratification: prior ET sensitivity; visceral metastases; menopausal status. Primary endpoint (EP) was investigator–assessed progression–free survival (PFS). Secondary EP: overall survival, response assessment, patient–reported outcomes, safety.

Results: By March 2015, median follow–up was 8.9 mo. 521 pts were randomized (PAL+F, 347; PLB+F, 174). Baseline characteristics were balanced. Median PFS was 9.5 (95% CI 9.2–11.0) mo (PAL+F) vs 4.6 (3.5–5.6) mo (PLB+F) (HR 0.46 [0.36–0.59], P&lt;0.001). Overall response (CR+ PR) was significantly improved with PAL+F (ITT: 19% vs 8.6%, P=0.001; pts with measurable disease: 24.6% vs 10.9%, P&lt;0.001). Clinical benefit (CBR=CR+PR+SD ?24wks) was 66.6% vs 39.7% (P&lt;0.001). Benefit from PAL was confirmed in pre– and postmenopausal pts with PFS in premenopausal 9.5 vs 5.6 mo (HR=0.50 [0.29–0.87], P=0.006) and in postmenopausal 9.9 vs 3.9 mo (HR=0.45 [0.34–0.59], P&lt;0.001). Common adverse events (AEs) for PAL+F vs PLB+F were neutropenia (80.9 vs 3.5%), leukopenia (49.6 vs 4.1%), and fatigue (39.1 vs 28.5%); febrile neutropenia occurred in 0.9% (P+ F) vs 0.6% pts (PLB+F). Discontinuation due to AEs was 4.0% on P vs 1.7% on PLB. The benefit of PAL+F vs PLB+F was compared in pts with various degrees of endocrine resistance: a) progression ≤12 mo of adjuvant ET completion, PFS 9.5 vs 5.4 mo (HR 0.55 [0.32–0.92], P=0.01); b) failed 1 line of ET, 10.2 vs 5.4 mo (HR 0.42 [0.29–0.59], P&lt;0.001); c) failed 2 lines of ET, 9.9 vs 1.8 mo (HR=0.20 [0.10– 0.39, P&lt;0.001); d) proven endocrine sensitive, 10.2 vs 4.2 mo (HR 0.42 [0.32–0.56], P&lt;0.001); e) proven no prior endocrine sensitivity, 7.5 vs 5.4 mo (HR 0.64 [0.39–1.07], P=0.04) f) AI most recent therapy, 9.5 vs 3.7 mo (HR 0.42 [0.31–0.56], P&lt;0.001).

Conclusion: Mature efficacy confirmed superior PFS and demonstrated significantly improved clinical response and CBR by the combination of ET and Palbociclib. It also consistently showed therapeutic benefit irrespective of menopausal status and various degrees of endocrine sensitivity. Safety profile is favorable. PAL+F may be an effective option for HR+ MBC pts.

Funding: Pfizer.

Citation Format: Cristofanilli M, Bondarenko I, Ro J, Im S-A, Masuda N, Colleoni M, DeMichele AM, Loi S, Verma S, Iwata H, Huang Bartlett C, Zhang K, Puyana Theall K, Turner NC, Slamon DJ. PALOMA3: Phase 3 trial of fulvestrant with or without palbociclib in pre- and postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer that progressed on prior endocrine therapy—confirmed efficacy and safety. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-01.

Abstract P2-02-04: Distinct clinical and biological values of subpopulations of circulating tumor cells (CTCs) in primary breast cancer

Background: CTCs represent a heterogeneous population of cells with different phenotypes and biological values. Epithelial to mesenchymal transition (EMT) gives rise to cells with stem cell-like properties with increased resistance to chemotherapy that may be under detected by currently approved assays. The aim of this study was to characterize CTCs based on the expression of epithelial and mesenchymal markers in primary breast cancer (BC) and to correlate them with patients'/tumor characteristics.

Methods: This prospective translational study included 422 patients with primary BC enrolled from March 2012 to February 2015. Blood for CTC detection was drawn before surgery (422 patients), before 1st cycle (95 patients) and before 2nd cycle (53 patients) of adjuvant therapy. Isolated peripheral blood mononuclear cells (PBMC) were depleted of cells of hematopoietic origin (CD45+) using RossetteSep kit (StemCell Technologies) negative selection with anti-CD45 antibody. RNA extracted from CD45-depleted (CD45) PBMC was interrogated for expression of EMT-inducing transcription factors (TWIST1, SNAIL1, SLUG, ZEB1) and epithelial (CK19) gene transcripts by quantitative reverse transcription-PCR. Expressions of gene transcripts in CD45- PBMC from patients were compared to those of CD45- PBMC of 60 healthy donors.

Results: Totally, CTCs were detected in 116/422 (27.5%) patients before surgery, in 21/95 (22.1%) patients after surgery and before 1st cycle and in 19/53 (35.8%) of patients before 2nd cycle of adjuvant therapy. Before surgery, CTCs exhibited only epithelial markers in 38 (9.0%) patients, only EMT markers in 68 (16.1%) of patients, while in 10 (2.4%) patients CTCs with both epithelial and EMT markers were detected. Epithelial CTCs were more often detected before surgery compared to after surgery (11.4% vs. 2.1%; p = 0.003), while mesenchymal CTCs were more often detected after the 1st cycle of chemotherapy as opposed to detection before surgery (30.2% vs. 18.2%; p = 0.05). Patients with N2-3 disease had more often detectable CTCs compared to patients with N0-1 disease (41.4% vs. 24.9%, p = 0.01) and this was mainly driven by mesenchymal CTCs (31.0% for N2-3 vs. 16.0% for N0-1; p = 0.007). Similarly, patients that lacked p53 expression (wild type TP53) in primary tumor had more often CTCs with EMT phenotype opposite to patients with p53 expression (p = 0.02). Presence of epithelial CTCs was significantly associated with lower absolute lymphocyte (p = 0.02) and neutrophil (p = 0.02) counts in peripheral blood.

Conclusions: Our results support the concept of CTCs phenotypic heterogeneity in breast cancer patients. These results support the role of EMT in cancer pathogenesis and suggest that CTCs with EMT phenotype are involved in tumor dissemination while their increase after chemotherapy might be a mechanism of treatment resistance. Moreover, these data suggest inverse relationship between immune cells and epithelial CTCs which stress the role of immune cells in tumor dissemination.

Citation Format: Mego M, Jurisova S, Karaba M, Minarik G, Benca J, Sedlackova T, Manasova D, Malejcikova M, Sieberova G, Macuch J, Gronesova P, Sufliarsky J, Pindak D, Cristofanilli M, Reuben JN, Mardiak J. Distinct clinical and biological values of subpopulations of circulating tumor cells (CTCs) in primary breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-04.

Abstract P2-02-11: Detection of activating estrogen receptor 1 (ESR1) mutation on single circulating tumor cells from metastatic breast cancer patients

Background: 65% of primary breast cancers express the estrogen receptor α (ERα) and the mainstay of treatment are therapies that result in selective estrogen receptor modulation (SERM) of estrogen deprivation (aromatase inhibitors, AIs). Even thought endocrine therapy resulted in reduced recurrence and mortality, a significant portion of patients relapse with a metastatic disease and subsequently progress while of therapy for advanced disease (endocrine resistance). Recent evidence showed that activating hot spot mutation in the ligand binding domain of the ERα are acquired on treatment (frequency of 20%) and can drive resistance to endocrine therapy. Circulating tumor cells (CTCs) provide a non-invasive accessible source of tumor material and the molecular profiling of these rare cells might lead to insight on disease progression and therapeutic strategies. These features suggest that the detection of ESR1 mutation on single CTC may be a useful biomarker for therapy guidance.

Purpose: Investigate the incidence and heterogeneity of ESR1 mutational status within single CTCs isolated from individual metastatic breast cancer patients (mBCs), combining the FDA approved CellSearch® system for enumeration of CTCs with the DEPArrayTM technologies.

Methods: CTCs were enriched and enumerate by CellSearch® in 7.5 ml blood samples collected from 21 mBCs according to standard protocol. Each CTC-enriched sample with at least 20 CTCs was recovered from Veridex cartridge and loaded into the DEPArrayTM A300K chip, since the DEPArrayTM analyzed only the 66% of the sample volume loaded, according to the manufacturer's instructions. The chip scanning was performed by automated fluorescence microscope. The loaded cells were recovered as single cell and subdivided in tree different group: Cytokeratin (CK) positive ( Dapi+, CK+, ER-, CD45-); ER positive (Dapi+, ER+, CK+, CD45-); White Blood cells (WBCs) (Dapi+, CD45+, CK-, ER-). Single CTCs and WBCs were then submitted to whole genome amplification (WGA) using the Single Cell WGA kit (Yikon Genomics) according the manufacturer's instructions. Detection of target 14 ESR1 hot spot mutations was performed on ABI PRISM® 3700 genetic analyzer by target Sanger sequencing.

Results: 3 out of 21 mBCs with ≥20 CTCs were sorted and a total of 65 cells were recovered. WGA and ESR1 mutational status were performed on a total of 25 cells (respectively 11 ER+, 6 CK+ and 8 WBCs). In 1 of the 3 patients, that failed 2 lines of chemotherapy and previous single agent endocrine therapy, molecular heterogeneity was detected among its ER+ cells. 4 of 5 ER+ cells were heterozygote for the Y537S while one cell was homozygous, maybe due to a loss of heterozygosity. Y537S is one of the most common mutations that leads to a ligand independent ER transcriptional activity that does not respond to endocrine manipulation. No mutations were reported in all the CK+ and WBC cells analyzed.

Conclusions: This study demonstrates the feasibility of a non-invasive approach based on liquid biopsy in mBCs. Evaluation of ER status and early identification of ESR1 mutation in ER+ CTCs might allow to predict effect of the endocrine therapies and switching to other treatments before the emergence of metastatic disease.

Citation Format: Paolillo C, Mu Z, Austin L, Nguyen T, Capoluongo E, Fortina P, Cristofanilli M. Detection of activating estrogen receptor 1 (ESR1) mutation on single circulating tumor cells from metastatic breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-11.

Progressive multiple sclerosis cerebrospinal fluid induces inflammatory demyelination, axonal loss, and astrogliosis in mice

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory demyelination and neurodegeneration throughout the CNS, which lead over time to a condition of irreversible functional decline known as progressive MS. Currently, there are no satisfactory treatments for this condition because the mechanisms that underlie disease progression are not well understood. This is partly due to the lack of a specific animal model that represents progressive MS. We investigated the effects of intracerebroventricular injections of cerebrospinal fluid (CSF) derived from untreated primary progressive (PPMS), secondary progressive (SPMS), and relapsing/remitting (RRMS) MS patients into mice. We found discrete inflammatory demyelinating lesions containing macrophages, B cell and T cell infiltrates in the brains of animals injected with CSF from patients with progressive MS. These lesions were rarely found in animals injected with RRMS-CSF and never in those treated with control-CSF. Animals that developed brain lesions also presented extensive inflammation in their spinal cord. However, discrete spinal cord lesions were rare and only seen in animals injected with PPMS-CSF. Axonal loss and astrogliosis were seen within the lesions following the initial demyelination. In addition, Th17 cell activity was enhanced in the CNS and in lymph nodes of progressive MS-CSF injected animals compared to controls. Furthermore, CSF derived from MS patients who were clinically stable following therapy had greatly diminished capacity to induce CNS lesions in mice. Finally, we provided evidence suggesting that differential expression of pro-inflammatory cytokines present in the progressive MS CSF might be involved in the observed mouse pathology. Our data suggests that the agent(s) responsible for the demyelination and neurodegeneration characteristic of progressive MS is present in patient CSF and is amenable to further characterization in experimental models of the disease.

Survival of women with inflammatory breast cancer: a large population-based study

BACKGROUND

Our group has previously reported that women with inflammatory breast cancer (IBC) continue to have worse outcome compared with those with non-IBC. We undertook this population-based study to see if there have been improvements in survival among women with stage III IBC, over time.

PATIENT AND METHODS

We searched the Surveillance, Epidemiology and End Results Registry to identify female patients diagnosed with stage III IBC between 1990 and 2010. Patients were divided into four groups according to year of diagnosis: 1990-1995, 1996-2000, 2001-2005, and 2006-2010. Breast cancer-specific survival (BCSS) was estimated using the Kaplan-Meier method and compared across groups using the log-rank test. Cox models were then fit to determine the association of year of diagnosis and BCSS after adjusting for patient and tumor characteristics.

RESULTS

A total of 7679 patients with IBC were identified of whom 1084 patients (14.1%) were diagnosed between 1990 and 1995, 1614 patients (21.0%) between 1996 and 2000, 2683 patients (34.9%) between 2001 and 2005, and 2298 patients (29.9%) between 2006 and 2010. The 2-year BCSS for the whole cohort was 71%. Two-year BCSS were 62%, 67%, 72%, and 76% for patients diagnosed between 1990-1995, 1996-2000, 2001-2005, and 2006-2010, respectively (P < 0.0001). In the multivariable analysis, increasing year of diagnosis (modeled as a continuous variable) was associated with decreasing risks of death from breast cancer (HR = 0.98, 95% confidence interval 0.97-0.99, P < 0.0001).

CONCLUSION

There has been a significant improvement in survival of patients diagnosed with IBC over a two-decade time span in this large population-based study. This suggests that therapeutic strategies researched and evolved in the context of non-IBC have also had a positive impact in women with IBC.