Comparative efficacy of adjuvant trastuzumab-containing chemotherapies for patients with early HER2-positive primary breast cancer: a network meta-analysis

BACKGROUND

Trastuzumab (H) with chemotherapy benefits patients with HER2+ breast cancer (BC); however, we lack head-to-head pairwise assessment of survival or cardiotoxicity for specific combinations. We sought to identify optimal combinations.

METHODS

We searched PubMed, updated October 2017, using keywords "Breast Neoplasms/drug therapy," "Trastuzumab," and "Clinical Trial" and searched Cochrane Library. Our search included randomized trials of adjuvant H plus chemotherapy for early-stage HER2+ BC, and excluding trials of neoadjuvant therapy or without data to obtain hazard ratios (HRs) for outcomes. Following PRISMA guidelines, one investigator did initial search; two others independently confirmed and extracted information; and consensus with another investigator resolved disagreements. Before gathering data, we set outcomes of overall survival (OS), event-free survival (EFS), and severe cardiac adverse events (SCAEs). Analyzing 6 trials and 13,621 patients, we made direct and indirect comparisons using network meta-analysis on HR for OS or EFS and on odds ratio (OR) for SCAE; ranked therapy was done based on outcomes using p scores.

RESULTS

Compared with anthracycline-cyclophosphamide with taxane (ACT), ACT with concurrent H (ACT+H) showed best OS (HR 0.63, 95% confidence interval [CI] 0.55, 0.72), followed by taxane and carboplatin (TC) with concurrent H (TC+H) (HR 0.77, 95% CI 0.59, 1) and ACT with sequential H (ACT-H) (HR 0.85, 95% CI 0.68, 1.05). Pairwise comparisons showed statistically significant OS benefit for ACT+H over others; similar results for EFS. TC+H showed statistically significant lower SCAE risk compared to ACT+H (OR 0.13, 95% CI 0.03, 0.61).

CONCLUSIONS

Concurrent H with ACT or TC showed most clinical benefit for early-stage HER2+ BC; TC+H had lowest cardiotoxicity.

Revisiting the definition of estrogen receptor positivity in HER2-negative primary breast cancer

Background

Although 1% has been used as cut-off for estrogen receptor (ER) positivity, several studies have reported that tumors with ER < 1% have characteristics similar to those with 1% ≤ ER < 10%. We hypothesized that in patients with human epidermal growth factor 2 (HER2)-negative breast cancer, a cut-off of 10% is more useful than one of 1% in discriminating for both a better pathological complete response (pCR) rate to neoadjuvant chemotherapy and a better long-term outcome with adjuvant hormonal therapy. Our objectives were to identify a percentage of ER expression below which pCR was likely and to determine whether this cut-off value can identify patients who would benefit from adjuvant hormonal therapy.

Patients and methods

Patients with stage II or III HER2-negative primary breast cancer who received neoadjuvant chemotherapy followed by definitive surgery between June 1982 and June 2013 were included. Logistic regression models were used to assess the association between each variable and pCR. Cox models were used to analyze time to recurrence and overall survival. The recursive partitioning and regression trees method was used to calculate the cut-off value of ER expression.

Results

A total of 3055 patients were analyzed. Low percentage of ER was significantly associated with high pCR rate (OR = 0.99, 95% CI = 0.986-0.994, P < 0.001). The recommended cut-off of ER expression below which pCR was likely was 9.5%. Among patients with ER ≥ 10% tumors, but not those with 1%≤ER < 10% tumors, adjuvant hormonal therapy was significantly associated with long time to recurrence (HR = 0.24, 95% CI = 0.16-0.36, P < 0.001) and overall survival (HR = 0.32, 95% CI = 0.2-0.5, P < 0.001).

Conclusion

Stage II or III HER2-negative primary breast cancer with ER < 10% behaves clinically like triple-negative breast cancer in terms of pCR and survival outcomes and patients with such tumors may have a limited benefit from adjuvant hormonal therapy. It may be more clinically relevant to define triple-negative breast cancer as HER2-negative breast cancer with <10%, rather than <1%, of ER and/or progesterone receptor expression.

Abstract OT3-05-07: PATINA: A randomized open label phase III trial to evaluate the efficacy and safety of palbociclib + anti HER2 therapy + endocrine therapy vs anti HER2 therapy + endocrine therapy after induction treatment for hormone receptor positive, HER2 positive metastatic breast cancer

Background

Pre-clinical data and initial results from clinical studies point to the added benefit of CDK4/6 inhibition when combined with anti-HER2 tx. The current study is designed to evaluate the added benefit of palbociclib when given in combination with anti-HER2 and endocrine tx maintenance in the 1st†line setting of metastatic HER2+HR+ breast cancer.

Trial design

PATINA is an international, open-label, pivotal Phase III study. Primary objective is to demonstrate that the combination of palbociclib with anti-HER2 plus endocrine tx is superior to anti-HER2 plus endocrine tx in prolonging PFS. Sample size is 496 pts. The study starts after completion of 6-8 cycles of chemotherapy-containing anti-HER2 tx for metastatic breast cancer in the 1st line setting. Pts are eligible provided they are without evidence of disease progression by local assessment (i.e. CR, PR or SD). To account for the need for less intense tx regimens for a subset of pts diagnosed with HER2+ER+ disease, clinicians may recommend the combination of trastuzumab with either a taxane or vinorelbine prior to study initiation. Clinicians might also choose a non-pertuzumab option for pts previously treated with pertuzumab in the neo(adjuvant) setting. Secondary objectives include measures of tumor control (OR, CBR, DOR), OS, safety and QOL. The translational science main objective is to compare PFS estimates according to PIK3CA mutation status assessed by cfDNA analysis. Endocrine tx options are AI or fulvestrant. Premenopausal pts must receive ovarian suppression. The study has a 90% power to detect a hazard ratio of 0.667 in favor of the palbociclib arm. Pts approached to participate in AFT-38 will be asked to indicate on the informed consent forms whether remaining biospecimens and clinical data from the control arm of the study can be shared with the Mastering Breast Cancer (MBC) Initiative. The overarching purpose of the MBC is to create a mechanism for understanding the natural history of metastatic breast cancer by cataloguing longitudinally studied tumor-specific markers and treatment effects.

ClinicalTrials.gov Identifier: NCT02947685

Citation Format: Metzger-Filho O, Mandrekar S, Loibl S, Ciruelos E, Gianni L, Lim E, Miller K, Huang C, Koehler M, Francis P, Valagussa P, Goel S, Prat A, Goetz M, Loi S, Krop I, Carey L, Lanzillotti J, Winer E, Tripathy D, DeMichele A. PATINA: A randomized open label phase III trial to evaluate the efficacy and safety of palbociclib + anti HER2 therapy + endocrine therapy vs anti HER2 therapy + endocrine therapy after induction treatment for hormone receptor positive, HER2 positive metastatic 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 OT3-05-07.

Abstract P1-16-02: Phase II study of the feasibility and safety of radium-223 dichloride in combination with hormonal therapy and denosumab for the treatment of patients with hormone receptor-positive breast cancer with bone-dominant metastasis

Background

Radium-223 dichloride (Ra-223) is a therapeutic alpha particle-emitting radiopharmaceutical compound which have antitumor effect targeted on bone metastases. Alpha particles induces double strand DNA breaks and localized cytotoxic effect to cancer cells with limiting harm on normal tissues. We are conducting a phase II clinical trial of combination of Ra-223, hormonal therapy, and denosumab treatment in patients with hormone receptor (HR)-positive bone-dominant metastatic breast cancer (NCT02366130). In this preliminary analysis of the study, we aimed to evaluate the feasibility and safety of this combination therapy.

Methods

This single-center phase II study seeks to determine the efficacy and safety of Ra-223 in combination with hormonal therapy and denosumab. Major eligibility criteria include HR-positive breast cancer with bone and/or marrow predominant metastases. Patients with two or more visceral metastases were not eligible. There was no limit in the number of prior hormonal therapies in the metastatic setting. Patients received Ra-223 injection (55 kBq/kg intravenously) on day 1 of the study and then every 4 weeks thereafter for 6 cycles. Patients were also administered a single hormonal agent (i.e., tamoxifen, aromatase inhibitor, or fulvestrant at standard doses) daily and denosumab (120 mg subcutaneously) every 4 weeks. For this analysis, adverse events (AEs) were summarized using descriptive statistics.

Results

A total of 25 patients were enrolled and 22 were evaluable between March 2015 and December 2016. Median age was 58.5 years (range 31-79), and 59% of patients were postmenopausal. ECOG performance status was 0 in 16 patients (73%), and 1 in six patients (27%). HER2/neu was positive in only one patient. Four patients (18%) were de novo metastasis, no patients had visceral metastasis, and multiple bone metastases in 20 patients (91%) vs. focal metastasis in 2 (9%). Median time from diagnosis of bone metastasis was 4.8 months (range 0.5-96.6). Prior therapy for metastatic disease consisted of hormonal therapy in 50% of the patients (eight patients with one line and three patients with two lines), chemotherapy (9%), palbociclib (14%), radiation to bone metastasis (50%), and bone-supportive therapy (27% with zoledronic acid, 27% with denosumab). The median number of cycles of Ra-223 administered was 6 (range 4-6).

The median follow-up time was 4 months (range 2-8). There were no grade 3 or 4 AEs. Major non-hematological grade 1 and 2 AEs were bone pain (77%), fatigue (45%), nausea (36%), diarrhea (32%), AST/ALT elevation (23%), hot flashes (23%), and headache (18%). The most common hematological AEs were grade 1 or 2 neutropenia (23%), anemia (14%), and thrombocytopenia (18%). There was no treatment delay or discontinuation due to AEs.

Conclusion

Our results suggest that the addition of Ra-223 to hormonal therapy and denosumab is a feasible and safe combination therapy in patients with HR-positive breast cancer with bone-dominant metastasis. We continue to enroll patients in the phase II trial to evaluate the efficacy of the treatment.

Citation Format: Tahara RK, Fujii T, Saigal B, Ibrahim NK, Damodaran S, Barcenas CH, Murray JL, Chasen BA, Shen Y, Liu DD, Hortobagyi GN, Tripathy D, Ueno NT. Phase II study of the feasibility and safety of radium-223 dichloride in combination with hormonal therapy and denosumab for the treatment of patients with hormone receptor-positive breast cancer with bone-dominant metastasis [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 P1-16-02.

Abstract P1-05-03: JNK signaling regulates tumor cell–tumor-associated macrophage cross-talk in triple-negative breast cancer

Despite advances in our understanding of the molecular mechanisms underlying the aggressiveness of triple-negative breast cancer (TNBC), the contribution of tumor-associated macrophages (TAMs) to TNBC pathogenesis has not been therapeutically exploited. TAMs are the most abundant cell types in the tumor microenvironment (TME) and the key contributor to tumor progression and invasion. We have found that c-Jun NH2-terminal kinase (JNK), a member of the MAPK family and a major regulator of inflammation, contributes to TNBC tumorigenesis by promoting the cancer stem-like cell phenotype. However, whether the JNK pathway regulates TAMs and their cross-talk with tumor cells in TNBC remains unknown. Here, we tested the hypothesis that JNK signaling contributes to TNBC aggressiveness by promoting the tumor cell–TAM cross-talk that facilitates TNBC cell invasiveness.

We found that, among 80 patients with primary inflammatory breast cancer (IBC), TNBC tumors (n=18) had 2-fold more TAMs than non-TNBC tumors (n=62, P=0.05) and that high TAM counts were correlated with shorter disease-free survival of patients with IBC (P=0.05). Both JNK1 and c-Jun were highly activated in TAMs, and JNK-IN-8, a pan-inhibitor of JNK, suppressed c-Jun activation. JNK-IN-8 also increased expression of M1 macrophage markers (CD80 and HLA-DR) but reduced expression of TAM markers (CD163 and CD206), suggesting that JNK suppresses M1 macrophage differentiation but promotes TAM differentiation. Co-culture with TAMs significantly enhanced migration and invasion of HCC70 and MDA-MB-468 human and 4T1 murine TNBC cells. Similarly, an enhancement in TNBC cells migration and invasion was observed following culture with TAM-conditioned medium, suggesting that TAMs enhance TNBC cellular activities through paracrine signaling. In addition, inhibition of JNK signaling in TNBC cells or in TAMs by JNK-IN-8 significantly suppressed TAM-promoted enhancement of TNBC cell migration and invasion. These studies strongly suggest that JNK regulates M1/TAM differentiation and TNBC cell–TAM cross-talk. Furthermore, cytokine/chemokine profiling analysis showed that, of the identified molecules, MCP-1 (secreted by TAMs) and VEGF (secreted by TNBC cells) had the highest expression levels and that their expression was dramatically reduced following JNK-IN-8 treatment. Stimulation with recombinant VEGF increased proliferation of MDA-MB-468 cells, and stimulation with recombinant MCP-1 enhanced migration of the cells. These findings suggest that VEGF and MCP-1 are involved in JNK-mediated TNBC cell–TAM cross-talk.

Together, our results suggest that JNK signaling regulates tumor cell–TAM cross-talk through MCP-1– and/or VEGF-mediated paracrine signaling and that JNK is an important therapeutic target in TNBC. Further animal studies using JNK-knockout TNBC cells co-injected with TAMs are needed to confirm our in vitro findings.

Citation Format: Xie X, Otsuka S, Chu K, Lu AY, Tripathy D, Dalby KN, Hittelman WN, Van Laere S, Bartholomeusz C, Ueno NT. JNK signaling regulates tumor cell–tumor-associated macrophage cross-talk in triple-negative 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 P1-05-03.

Abstract P1-16-04: Somatic mutations, clinicopathologic characteristics, and survival in patients with untreated breast cancer with bone-only and non-bone sites of first metastasis

Background: Bone is the most common site of metastasis of breast cancer, and bone metastasis is associated with a high rate of skeletal-related events, all of which contribute to decreased quality of life and poor outcomes. Biological mechanisms of metastasis to bone may be unique, and identification of distinct signaling pathways and somatic mutations may provide biological insight into or rational targets for treatment of and prevention of bone metastasis. The aims of this study were to compare and contrast somatic mutations, clinicopathologic characteristics, and survival in breast cancer patients with bone only versus non-bone as first metastatic site.

Methods: Tumor samples were collected from 389 patients who had metastasis and untreated primary breast cancer. In each sample, 46 or 50 cancer-related genes were selectively amplified and analyzed for mutations by AmpliSeq Ion Torrent next-generation sequencing. We used Fisher's exact test to identify somatic mutations associated with bone-only first metastasis and logistic regression models to identify differences in clinicopathologic characteristics, survival, and somatic mutations between patients with bone-only first metastasis and patients with first metastasis in non-bone sites only (“other-only first metastasis”).

Results: Among the 389 patients, the first metastasis was located in bone only in 72 patients (18.5%), non-bone sites only in 223 patients (57.3%), and both in 94 patients (24.2%). Of the cancer-related genes analyzed, the most commonly mutated were TP53 (N=103), PIK3CA (N=79), AKT (N=13), and PTEN (N=2). Compared to patients with other-only first metastasis, patients with bone-only first metastasis had higher rates of hormone-receptor-positive disease, non-triple-negative subtype, and low nuclear grade (grade 1 or 2) (all 3 comparisons, p&lt;0.001); had a lower ratio of cases of invasive ductal carcinoma to cases of invasive lobular carcinoma (p=0.002); and tended to have a higher 5-year overall survival (OS) rate (78.2% [95% confidence interval (CI), 68.6%-89.0%] vs 55.0% [95% CI, 48.1%-62.9%]; p=0.051). However, in the subgroup of patients with TP53 mutation and in the subgroup of patients with PIK3CA mutation, OS did not differ between patients with bone-only and other-only first metastasis (p=0.49 and p=0.68; respectively). In univariate analysis, the rate of TP53 mutation tended to be lower in patients with bone-only first metastasis than in those with other-only first metastasis (15.3% vs 29.1%; p=0.051). In multivariate analysis, TP53 mutation was not significantly associated with site of first metastasis (p=0.54) but was significantly associated with hormone-receptor-negative disease (p&lt;0.001).

Conclusions: We did not find associations between somatic mutations and bone-only first metastasis in patients with untreated breast cancer. Patients with bone-only first metastasis have longer OS than patients with other-only first metastasis. More comprehensive molecular analysis may be needed to further understand the factors associated with bone-only metastatic disease in breast cancer.

Citation Format: Kono M, Fujii T, Matsuda N, Harano K, Chen H, Wathoo C, Aron JY, Tripathy D, Meric-Bernstam F, Ueno NT. Somatic mutations, clinicopathologic characteristics, and survival in patients with untreated breast cancer with bone-only and non-bone sites of first metastasis [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 P1-16-04.

Abstract P5-13-01: Effects of a 16-week combined aerobic and resistance exercise intervention on metabolic syndrome in overweight/Obese Hispanic breast cancer survivors

Purpose. Metabolic syndrome (MetS) is associated with increased risk of cardiovascular disease, type 2 diabetes, and possibly cancer recurrence, and is higher in breast cancer survivors than age-matched postmenopausal women. Further, MetS is 1.5 times more prevalent in Hispanic women (&gt;40 years of age) than in non-Hispanic Whites and African Americans, thereby increasing the need to attenuate MetS in Hispanic breast cancer survivors (HBCS). This study examined the effects of a 16-week combined aerobic and resistance exercise intervention on MetS in overweight and obese HBCS.

Methods. This pre-planned sub-analysis included 60 sedentary HBCS (BMI325 kg/m2) from our larger MetS trial. HBCS were randomized to the exercise intervention (EXE; n=30) or usual care (UC; n=30). The EXE group participated in 3 supervised exercise sessions per week for 16 weeks. Aerobic exercise was performed at 65-85% heart rate maximum for ˜30 minutes. Resistance exercise was performed in circuit-fashion with 3 sets of 10-15 repetitions including upper and lower body exercises at 65-85% 1-repetition maximum. The UC group was asked not to increase their current exercise levels during the study period. Participants were tested for MetS (blood pressure, waist circumference, fasting blood glucose, HDL-C, and triglycerides) at baseline, within one week following the 16-week study period, and at 12-week follow-up for the EXE group only. Fasting blood samples were used to measure glucose, HDL-C, and triglycerides. Waist circumference was measured at the midpoint between the lower margin of the last palpable rib and the top of the iliac crest using a fabric tape measure. Blood pressure was measured with an automated sphygmomanometer. Body composition was assessed via dual energy X-ray absorptiometry.

Results. At baseline, 82% (overall and by group) of the HBCS met the criteria for MetS. There were no significant group differences in the MetS variables between the EXE and UC groups at baseline (p&gt;0.01). Post-intervention, all MetS components were significantly lower in the EXE group than the UC group (p&lt;0.01) and only 15% of participants in the EXE group met the criteria for MetS, representing a 67% absolute decrease. This is in comparison to 84% of participants in the UC group. Body fat mass decreased by 10% during the 16-week EXE period, compared to a 2% increase in the UC group (p&lt;0.01). MetS changes remained significantly improved in the EXE group when fat mass was included as a covariate in the statistical model. At the follow-up assessment in the EXE group, all MetS variables remained significantly improved compared to baseline (p&lt;0.01) and were not significantly different post-intervention (p&gt;0.25) despite slight increases (&lt;2%) in waist circumference and triglyceride levels.

Conclusion. This is one of few exercise trials in minority BCS and the first study to target MetS with exercise in HBCS. This 16-week supervised combined aerobic and resistance exercise intervention reduced MetS in sedentary, overweight and obese HBCS. Reductions in MetS components were maintained after completion of the intervention, suggesting the benefits of the intervention on MetS were sustainable in the absence of a supervised intervention.

Citation Format: Dieli-Conwright CM, Sami N, Lee K, Spicer D, Buchanan TA, Demark-Wahnefried W, Courneya K, Tripathy D, Mortimer J. Effects of a 16-week combined aerobic and resistance exercise intervention on metabolic syndrome in overweight/Obese Hispanic breast cancer survivors [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 P5-13-01.

Abstract P5-21-15: The synergistic antitumor activity of entinostat (MS-275) in combination with palbociclib (PD 0332991) in estrogen receptor-positive and triple-negative breast cancer

BACKGROUND: CDK4/6 regulates the G1-S phase transition by phosphorylating the retinoblastoma protein (Rb). Given their potent clinical efficacy, CDK4/6 inhibitors used in combination with hormone receptor (HR) blockade (with an aromatase inhibitor or fulvestrant) are emerging as the standard of care for patients with metastatic HR-positive breast cancers. The CDK4/6 inhibitors palbociclib and ribociclib are FDA-approved for use in HR-positive breast cancer patients, and abemaciclib is currently in phase III trials. We observed that approximately 74% (25/34) of breast cancer cell lines had high phosphorylated Rb (phospho-Rb) expression levels and that triple-negative breast cancer (TNBC) cell lines often expressed phospho-Rb, suggesting that targeting phospho-Rb via CDK4/6 inhibition may be effective against TNBC. The histone deacetylase (HDAC) inhibitors increase p21Cip1 levels, promoting proteasomal degradation of cyclin B1 and resulting in G2/M arrest. Entinostat is an oral, class 1, selective HDAC inhibitor currently in phase III testing in HR-positive breast cancer. Preclinical and clinical data demonstrate that entinostat, in combination with HR blockade, has anticancer activity. Our group recently reported that entinostat combined with other anticancer drugs induced apoptosis via induction of proapoptotic proteins such as Noxa and Bim in breast cancer cell lines. Based on these findings, we hypothesized that entinostat-induced apoptosis and palbociclib-induced cell cycle arrest synergize to produce enhanced antitumor effects in estrogen receptor (ER)-positive breast cancer and TNBC cell lines with high phospho-Rb expression levels.

METHODS: We assessed the combination antitumor effects and their mechanisms via CellTiter Blue and sulforhodamine B assays, flow cytometry, apoptosis (caspase 3/7) assays, anchorage-independent growth assays, Western blotting, reverse phase protein array (RPPA), and mammary fat pad xenograft mouse models.

RESULTS: RPPA data showed that ER-positive and TNBC cell lines more often expressed phospho-Rb than did other breast cancer cell subtypes (7/10 and 8/17 cell lines, respectively). We found that the combination of entinostat and palbociclib synergistically inhibited tumor cell proliferation (combinational index less than 1.0), reduced in vitro colony formation (P &lt; 0.05), inhibited in vivo tumor growth in ER-positive MCF-7 breast cancer cells (P &lt; 0.05), and inhibited tumor growth in TNBC xenograft mouse models (MDA-MB-231) more effectively than did either drug alone.

CONCLUSION: Taken together, our data provide evidence that combining entinostat with palbociclib enhances the antitumor effects of these drugs. Along with our continued effort to determine predictive biomarkers, our findings justify conducting a clinical trial of combination treatment with entinostat and palbociclib in patients with ER-positive breast cancer or TNBC.

Citation Format: Lee J, Lim B, Pearson T, Tripathy D, Ordentlich P, Ueno NT. The synergistic antitumor activity of entinostat (MS-275) in combination with palbociclib (PD 0332991) in estrogen receptor-positive and triple-negative 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 P5-21-15.

Abstract P2-01-04: The whole transcriptional landscape of circulating tumor cells compared to metastases in stage IV breast cancer

Background: Metastatic breast cancer (MBC) and the circulating cells (CTCs) leading to macrometastasis are inherently different than primary breast cancer, evolving under the selection pressure of systemic therapy. A better understanding of the tumor biology of CTCs compared to metastasis may shed light on treatment opportunities.

Methods: We performed whole transcriptome sequencing (RNA Seq) on fresh metastatic tumor biopsies (mets), CTCs, and peripheral blood (PB) from 21 newly diagnosed MBC patients. CTCs were harvested using the ANGLE Parsortix to isolate cells based on size and deformability. Data were analyzed for differential expression, pathways, single nucleotide variants (SNV), fusions, intrinsic subtype, and a CTC-mets shared gene signature was validated using data from The Cancer Genome Atlas (TCGA). Detailed clinical-pathological and treatment data was evaluated.

Results: CTCs as a group showed much stronger gene expression of oncogenes, stem cell genes, keratins and mesenchymal markers than did mets from the same patients. Matched patient comparisons for 66 potentially clinically actionable genes for 8/9 pathways showed no significant difference in gene expression targets between CTCs and mets on ANOVA, although fold-change did vary. Eight SNVs in the ESR1 gene (n=5 patients) and 5 SNVs in the HER2 gene (n=2 patients) were shared between CTCs and distant metastases.

Differential gene expression analysis identified a signature of 8870 genes that were statistically significantly correlated between CTCs and mets (FDR adjusted p&lt;0.05). Ingenuity pathway analysis was applied to the list of genes shared between CTCs and mets, with analysis of canonical pathways and upstream regulators revealing numerous oncogenes and breast cancer related genes. The top upstream regulators of CTCs-mets were beta-estradiol, progesterone, FOXA1, HNRPA2B1 and HNF1A. The top 50 genes of this CTC-mets shared signature were prognostic of worse overall survival in the TCGA breast cancer dataset (p&lt;0.001), which included 817 patients with a median follow-up of 59.5 months. Second time-point data for n=5 patients with subsequent PB draws 6 months after baseline is currently pending. Intrinsic subtyping of mets by either NanoString assays or RNA Seq were not concordant with intrinsic subtyping of CTCs by RNA Seq.

Four of 21 CTC samples showed strong whole transcriptome RPKM correlation with PB (R2)&gt;0.9, however, 3/21 CTC samples showed strong whole transcriptome RPKM correlation with mets (R2)&gt;0.8. The remainder showed low correlation with both. Coverage was 91.4X for CTCs, 140.2X for mets and 138.5X for PB.

Conclusions: We present the transcriptomic landscape of CTCs with comparison to metastases and peripheral blood all acquired prior to treatment of newly diagnosed Stage IV breast cancer. Multiple genes, including oncogenes and stem cell genes, were found with higher expression in CTCs versus metastases. When focusing on 66 known potentially clinically actionable genes in breast cancer, CTCs did not show significantly different patterns of expression than mets in terms of up-regulation versus down-regulation compared to PB. RNA Seq of CTCs may be utilized to identify molecular alterations that are potentially clinically actionable.

Citation Format: Ring A, Porras T, Campo D, Kaur P, Forte VA, Tripathy D, Lu J, Zada G, Wagle N, Wecsler JS, Lang JE. The whole transcriptional landscape of circulating tumor cells compared to metastases in stage IV 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 P2-01-04.

Abstract P5-16-01: Documenting and sharing breast cancer knowledge from National Cancer Institute designated comprehensive cancer centers (NCI-CCCs) with community oncologists

Introduction:Tumor boards (TB) at National Cancer Institute Designated Comprehensive Cancer Centers (NCI-CCC) are an important source of multidisciplinary education. Unfortunately, expert knowledge from NCI-CCCs is not systematically documented and made accessible to oncologists in the community. This represents a lost opportunity to capture and share clinical expertise that can impact patient care in community centers. Using an online oncologist-only social network, we sought to demonstrate the feasibility of systematically documenting expert insights from TBs and department conferences at NCI-CCCs in order to expand their reach and provide educational benefit to the greater oncology community.

Methods: A pilot program was developed at the University of Texas MD Anderson Cancer Center (MDACC) to design a process in which discussions at departmental breast cancer conferences would be distilled down to clinical questions and answers (Q&A) and posted on theMednet.org, an online social Q&A website of over 3,800 US oncologists. An educational breast cancer conference was selected during a site visit. A faculty member was selected to distil discussions about patient management from the selected conference into a question that addressed the clinical situation being discussed. After the question was posted, the oncologist leading the discussion answered the question on theMednet. The Q&A was then indexed and stored for easy search retrieval and disseminated in a weekly newsletter to all registered medical oncologists. A detailed manual was created to document operating procedures for implementation at additional institutions.

Results: After developing the process at MDACC, the program was expanded to 2 additional NCI-CCCs- University of Pittsburgh (UPMC) and UCLA. The educational breast cancer conferences selected varied by site and were the new patient planning conference at MDACC, tumor board at UPMC, and multidisciplinary clinic at UCLA. The most significant factor for success was involvement of one faculty member who regularly identified educational questions and additional faculty who posted their answers. Between December 2016 and May 2017, 17 answers to 17 questions were posted and shared with over 1,200 medical oncologists via an email newsletter. All questions were focused on topics not answered by NCCN or ASCO guidelines. The majority of questions focused on management decisions around chemotherapy and endocrine therapy. Answers were viewed by 339 oncologists at 260 institutions in 47 states. This included 190 community practices and 70 academic medical centers.

Conclusion: We developed a process of capturing and sharing expert knowledge at NCI-CCC breast cancer conferences on questions not answered by current guidelines. These discussions are otherwise not documented or shared outside of academic centers. By translating discussions into actionable Q&A on an online oncologist network, we made them easily accessible to oncologists at nearly 200 community practices. Future efforts will be aimed at implementing the program into the breast cancer programs at additional NCI-CCCs.

Citation Format: Kalra M, Karuturi M, Tripathy D, Jankowitz R, McCann K, Brufsky A, Hurvitz S, Bogler O, Housri S, Housri N. Documenting and sharing breast cancer knowledge from National Cancer Institute designated comprehensive cancer centers (NCI-CCCs) with community oncologists [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 P5-16-01.

Abstract OT2-07-10: ATTAIN: Phase 3 study of etirinotecan pegol (EP) vs treatment of physician's choice (TPC) in patients (pts) with metastatic breast cancer (MBC) who have stable brain metastases (BM) previously treated with an anthracycline, a taxane, and capecitabine (ATC)

Background: EP is a next generation topoisomerase I inhibitor-polymer conjugate that provides continuous exposure to SN-38, the active metabolite. A BM mouse model showed high penetration and retention of SN-38 in CNS lesions, resulting in decreased size of CNS lesions and improved survival (OS) at concentrations achieved at the recommended dose in pts (Adkins BMC Cancer 2015). A Phase 3 trial (BEACON) of EP vs TPC in 852 pts with advanced BC did not meet its primary endpoint of OS (HR 0.087 p=0.08); a subset of 67 pts with stable BM showed improved OS (HR 0.51 [95% CI 0.30-0.86] p&lt;0.01) (Perez Lancet Oncol 2015). The current Phase 3 trial (ATTAIN) was designed for this subpopulation of pts having high unmet medical need.

Methods: Pts with MBC with locally treated stable BM will be randomized 1:1 to EP vs TPC in an open-label, randomized Phase 3 study. Eligibility includes ECOG PS 0 or 1; adequate organ function who received prior ATC (in neo/adjuvant or locally advanced/MBC setting) pts must have had ≥1 prior cytotoxic regimen for MBC (triple negative BC) ≥2 prior cytotoxic regimens and either 1 prior hormone therapy (HR+ BC) or 1 prior HER2 targeted therapy (HER2+ BC). Pts must have undergone definitive local therapy of BM (whole brain radiation [RT] stereotactic RT or surgical resection as single-agent or combination) signs/symptoms of BM must be stable with steroids unchanged or decreasing for ≥ 7 days prior to randomization. Primary endpoint is OS. Key secondary endpoints: ORR and PFS by RECIST v1.1 and RANO-BM, clinical benefit rate (ORR+SD ≥ 6 months) and QoL. Pts randomized to TPC will receive 1 of 7 IV cytotoxic agents. Pts are stratified by region, PS and receptor status. 350 pts will be randomized to obtain number of events required at 90% power to detect a statistically significant improvement in OS (hypothesizing HR=0.67) 1 interim analysis at 50% of deaths (130 events) will be performed. PK sampling and UGT1A1 testing will be performed in the EP arm; plasma ctDNA will be assessed for potential predictive markers of efficacy. Enrollment began early 2017. For enrollment information contact Dr. Alison Hannah, Dr. Mary Tagliaferri, or Minnie Kuo at StudyInquiry@nektar.com. NCT02915744

Citation Format: Tripathy D, Sara T, Seidman AD, Anders CK, Ibrahim N, Rugo HS, Twelves CJ, Diéras V, Müller V, Hannah A, Tagliaferri M, Cortés J. ATTAIN: Phase 3 study of etirinotecan pegol (EP) vs treatment of physician's choice (TPC) in patients (pts) with metastatic breast cancer (MBC) who have stable brain metastases (BM) previously treated with an anthracycline, a taxane, and capecitabine (ATC) [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 OT2-07-10.

Abstract OT3-05-03: POLARIS: Palbociclib (P) in hormone receptor-positive (HR+) advanced breast cancer: A prospective multicenter noninterventional study

Background: P is a novel cyclin-dependent kinase 4/6 inhibitor approved in the United States and Canada in combination with endocrine therapy for HR+/human epidermal growth factor receptor 2–negative (HER2-) advanced breast cancer (ABC). Despite promising trial results, not all patients respond to P. Moreover, despite a median age at diagnosis of 62 years, elderly patients are underrepresented in targeted therapy trials, including the PALOMA studies assessing P. It is important to understand P use in real-world practice settings, including tolerability and outcomes in the vulnerable older population. In addition, understanding the mechanisms of P response or resistance is critical to identify clinical factors and biomarkers that can predict which patients will benefit from P. This multicenter observational and biomarker study will seek to address these and other data gaps.

Trial Design: This is a prospective, noninterventional study of 1500 patients treated with P from 100 US and 10 Canadian sites. Study duration will span 2 years of recruitment and 3 years of follow-up after P treatment, until patient withdrawal from the study or death. Study participation is not intended to alter routine treatment; all treatment decisions, including type and timing of disease monitoring, are at the discretion of the treating physician and patient.

Eligibility: Eligible patients are aged ≥18 years with a diagnosis of adenocarcinoma of the breast with (1) evidence of advanced or metastatic disease not amenable to treatment with curative intent, (2) documented HR+/HER2- status, and (3) planned treatment with P. Patients with a life expectancy &lt;3 months at initial diagnosis, those participating in interventional trials, and those receiving active treatment for malignancies other than ABC at enrollment are ineligible.

Aims: In a large real-world cohort of HR+/HER2- ABC patients treated with P in routine clinical practice, this study aims to assess the following: prescribing and treatment patterns for ABC before, during, and after P therapy; overall clinical response to P; biomarker assessment investigating potential mechanisms of response and resistance to P based on genomic analyses of blood samples; patient quality of life, as measured by the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30; geriatric assessments in patients aged ≥70 years at enrollment based on the G8 Geriatric Screening Tool and the Activities of Daily Living questionnaire; and sequencing of treatment for metastatic disease. Other outcomes to be assessed include survival and toxicity.

Methods: Data will be collected from routine clinical assessments. Patients will have the option to provide blood samples drawn at standard-of-care intervals at baseline, during P treatment, and at the end of treatment for potential biomarker identification. Analyses will be primarily descriptive, with point estimates and confidence intervals as well as Kaplan-Meier methods used to assess time-to-event outcomes.

Accrual: Presently, 46 patients from 20 sites are enrolled.

Funding: Pfizer Inc.

Citation Format: Tripathy D, Bardia A, Blum JL, Rocque G, Wilks S, Lakhanpal S, Migas J, Cappelleri J, Perkins J, Comstock G, Wang Y. POLARIS: Palbociclib (P) in hormone receptor-positive (HR+) advanced breast cancer: A prospective multicenter noninterventional study [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 OT3-05-03.

Mutations in TGM6 induce the unfolded protein response in SCA35

Spinocerebellar ataxia type 35 (SCA35) is a rare autosomal-dominant neurodegenerative disease caused by mutations in the TGM6 gene, which codes for transglutaminase 6 (TG6). Mutations in TG6 induce cerebellar degeneration by an unknown mechanism. We identified seven patients bearing new mutations in TGM6. To gain insights into the molecular basis of mutant TG6-induced neurotoxicity, we analyzed all the seven new TG6 mutants and the five TG6 mutants previously linked to SCA35. We found that the wild-type (TG6-WT) protein mainly localized to the nucleus and perinuclear area, whereas five TG6 mutations showed nuclear depletion, increased accumulation in the perinuclear area, insolubility and loss of enzymatic function. Aberrant accumulation of these TG6 mutants in the perinuclear area led to activation of the unfolded protein response (UPR), suggesting that specific TG6 mutants elicit an endoplasmic reticulum stress response. Mutations associated with activation of the UPR caused death of primary neurons and reduced the survival of novel Drosophila melanogaster models of SCA35. These results indicate that mutations differently impacting on TG6 function cause neuronal dysfunction and death through diverse mechanisms and highlight the UPR as a potential therapeutic target for patient treatment.

Designing Dual Transglutaminase 2/Histone Deacetylase Inhibitors Effective at Halting Neuronal Death

In recent years there has been a clear consensus that neurodegenerative conditions can be better treated through concurrent modulation of different targets. Herein we report that combined inhibition of transglutaminase 2 (TG2) and histone deacetylases (HDACs) synergistically protects against toxic stimuli mediated by glutamate. Based on these findings, we designed and synthesized a series of novel dual TG2-HDAC binding agents. Compound 3 [(E)-N-hydroxy-5-(3-(4-(3-oxo-3-(pyridin-3-yl)prop-1-en-1-yl)phenyl)thioureido)pentanamide] emerged as the most interesting of the series, being able to inhibit TG2 and HDACs both in vitro (TG2 IC₅₀ =13.3±1.5 μm, HDAC1 IC₅₀ =3.38±0.14 μm, HDAC6 IC₅₀ =4.10±0.13 μm) and in cell-based assays. Furthermore, compound 3 does not exert any toxic effects in cortical neurons up to 50 μm and protects neurons against toxic insults induced by glutamate (5 mm) with an EC₅₀ value of 3.7±0.5 μm.

Long-term survival outcomes of triple-receptor negative breast cancer survivors who are disease free at 5 years and relationship with low hormone receptor positivity

Background:

We counsel our triple-negative breast cancer (TNBC) patients that the risk of recurrence is highest in the first 5 years after diagnosis. However, there are limited data with extended follow-up on the frequency, characteristics, and predictors of late events.

Methods:

We queried the MD Anderson Breast Cancer Management System database to identify patients with stage I–III TNBC who were disease free at 5 years from diagnosis. The Kaplan–Meier method was used to estimate yearly recurrence-free interval (RFI), recurrence-free survival (RFS), and distant relapse-free survival (DRFS), as defined by the STEEP criteria. Cox proportional hazards model was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs).

Results:

We identified 873 patients who were disease free at least 5 years from diagnosis with median follow-up of 8.3 years. The 10-year RFI was 97%, RFS 91%, and DRFS 92% the 15-year RFI was 95%, RFS 83%, and DRFS 84%. On a subset of patients with oestrogen receptor and progesterone receptor percentage recorded, low hormone receptor positivity conferred higher risk of late events on multivariable analysis for RFS only (RFI: HR=1.98, 95% CI=0.70–5.62, P-value=0.200; RFS: HR=1.94, 95% CI=1.05–3.56, P-value=0.034; DRFS: HR=1.72, 95% CI=0.92–3.24, P-value=0.091).

Conclusions:

The TNBC survivors who have been disease free for 5 years have a low probability of experiencing recurrence over the subsequent 10 years. Patients with low hormone receptor-positive cancers may have a higher risk of late events as measured by RFS but not by RFI or DRFS.

Abstract OT2-01-22: NCT02456857: A phase II trial of liposomal doxorubicin, bevacizumab and everolimus (DAE) in patients (pts) with localized triple-negative breast cancer (TNBC) with tumors predicted insensitive to standard neoadjuvant chemotherapy (NACT)

BACKGROUND: Approximately 50% of TNBC pts treated with standard taxane/anthracycline-based NACT will have chemo-insensitive disease (CID) manifested as extensive residual disease (RCB-II or III) at the time of surgery. 40-80% of these pts will develop recurrence within 3 years of initial diagnosis. Recent advances in molecular profiling have identified subsets of TNBC with distinct, targetable molecular features. We developed a clinical trial to identify and characterize CID (ARTEMIS: A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival). In the ARTEMIS trial, treatment naïve pts with localized TNBC undergo a pretreatment biopsy and then immediately start their initial phase of anthracycline-based chemotherapy so that the results of the molecular characterization are used in combination with response assessment (clinical exam/diagnostic imaging) to identify CID and inform the second phase of NACT, thus using a 'second hit' strategy in the middle of NACT to overcome drug resistance. The mesenchymal subtypes of TNBC have a high incidence of PI3K pathway activation. Preclinical models demonstrated response to PI3K inhibitors in this subtype. Metaplastic breast cancers make up ∼30% of tumors characterized as 'claudin-low/mesenchymal' by gene signature and are also associated with a high rate of PI3K activating molecular aberrations. A combination regimen of liposomal doxorubicin, bevacizumab and the mTOR inhibitors temsirolimus or everolimus (DAT or DAE) demonstrated response (including durable complete responses) in metastatic metaplastic breast cancer.

PRIMARY OBJECTIVE: Determine the rate of pathologic complete response (pCR/RCB-0) or minimal residual disease (RCB-I) after 4 cycles of DAE for treatment of mesenchymal TNBC deemed to be CID through the ARTEMIS trial

TRIAL DESIGN AND STATISTICAL METHODS: Only pts deemed to have mesenchymal CID on the ARTEMIS trial can enter this non-randomized phase II study. Realizing that pts without response to their initial cycles of chemotherapy have very low chance (5%) of achieving pCR with additional cycles of chemotherapy, it would be clinically meaningful to see pCR in this pt population improved to 20%. Counting pCR (RCB-0) or RCB-I as response, a two-stage Gehan-type design will be employed with 14 pts in the first stage. If at least one pt responds, 23 more pts will be added for a total of 37 pts. This design has a 49% chance of terminating after the first stage if the true response rate is 0.05, 23% chance if the true rate is 0.10, 10% if the true rate is 0.15 and 4% if the true rate is 0.20. If accrual continues to the second stage and a total of 37 pts are enrolled, the 95% confidence interval for a 0.20 response rate will extend from 0.10 to 0.35.

BRIEF ELIGIBILITY CRITERIA: Inclusion: localized TNBC enrolled onto ARTEMIS trial, adequate organ, bone marrow and cardiac parameters Exclusion: metastatic disease, pregnant or lactating pts, medical illness that increases chance of moderate to severe toxicity

CORRELATIVE SCIENCE: Correlate vimentin expression by IHC, mesenchymal signatures and PI3K pathway aberrations with response.

Citation Format: Moulder S, Hess K, Rauch M, Astrada B, Litton J, Mittendorf E, Ueno N, Tripathy D, Lim B, Piwnica-Worms H, Thompson A, Symmans WF. NCT02456857: A phase II trial of liposomal doxorubicin, bevacizumab and everolimus (DAE) in patients (pts) with localized triple-negative breast cancer (TNBC) with tumors predicted insensitive to standard neoadjuvant chemotherapy (NACT) [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 OT2-01-22.

Abstract P5-08-27: Treatment patterns and clinical outcomes in patients with hormone receptor (HR)+ HER2+ metastatic breast cancer and low vs high levels of HR positivity from the SystHERs Registry

Introduction In 2010, the cutoff for HR positivity in breast cancer was established as ≥1% of cells staining HR+, previously having varied from 1% to 10%. The impact of this change on treatment patterns and outcomes is poorly understood. SystHERs is a prospective, observational cohort registry of patients (pts) with HER2+ metastatic breast cancer (MBC) that commenced enrollment in 2012. To our knowledge, SystHERs is the largest registry to collect and analyze data for the HER2+ subgroup. We report baseline characteristics, treatment patterns, and early outcomes by %HR+ (1–9% vs 10–100%).

Methods SystHERs enrolled pts aged ≥18 years and within 6 months of HER2+ MBC diagnosis. For pts with locally-determined HR+ disease, defined as HR+ in primary or metastatic tissue, %HR+ is the highest percentage of ER+ or PR+ tissue in early breast cancer or MBC. The percentage of ER+ or PR+ cells was not reported for pts considered HR– by the investigator. Median overall survival (OS; Kaplan–Meier) and hazard ratios (Cox regression) were estimated.

Results As of Feb 1, 2016, data were available for 872 eligible pts with known HR status, of whom 608 (70%) had HR+ disease. Of the 608 pts, 53 (9%) had 1–9%HR+ and 496 (82%) had 10–100%HR+; %HR+ was not reported for 59 pts. Baseline characteristics were similar between %HR+ subgroups (Table 1).

As shown in Table 2, the 1–9%HR+ subgroup was less likely to receive first-line hormonal therapy (26%) than the 10–100%HR+ subgroup (56%). 87% and 79% of pts received chemotherapy, respectively.

Median time from MBC diagnosis was 16.5 months (range, 0.4–49.4 months). Median OS was not reached at the data cutoff. The number of deaths was 13 (25%) in the 1–9%HR+ subgroup, and 68 (14%) in the 10–100%HR+ subgroup (log-rank P=0.025). The OS hazard ratio (0.514, 95% CI 0.283–0.931) favored the 10–100%HR+ subgroup. OS did not differ significantly between pts with 1–9%HR+ vs HR– disease (log-rank P=0.582, hazard ratio 1.185, 95% CI 0.647–2.169).

Table 1. Baseline characteristics 1-9%HR+ (n=53)10-100%HR+ (n=496)HR– (n=264)Age at MBC diagnosis, median yrs (range)54 (30–86)57 (21–86)55 (28–88)Race, %   White838372Black151320Premenopausal, %282522ECOG performance status, %   04654441463942≥2878MBC diagnosis type, %   De novo404958Recurrent605142Visceral, %*686275*Non-hepatic abdominal, ascites, CNS, liver, lung, or pleural effusion sites of metastasis

Table 2. First-line treatment 1-9%HR+ (n=53)10-100%HR+ (n=496)HR– (n=264)HER2-targeted therapy, %969391Chemotherapy, %877989Hormonal therapy, %26564

Conclusions These preliminary observational data suggest potential differences in treatment patterns and survival outcomes in low vs moderate/high HR+ expressers, with the former being less likely to receive hormonal therapy (26% vs 56%). Furthermore, low HR positivity was associated with poorer OS and was similar to OS observed in pts with HR– disease.

Citation Format: Jahanzeb M, Tripathy D, Rugo H, Swain S, Kaufman PA, Mayer M, Hurvitz S, O'Shaughnessy J, Mason G, Yardley DA, Brufsky A, Chu L, Antao V, Beattie M, Yoo B, Cobleigh M. Treatment patterns and clinical outcomes in patients with hormone receptor (HR)+ HER2+ metastatic breast cancer and low vs high levels of HR positivity from the SystHERs Registry [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 P5-08-27.