Targeted methylation sequencing of plasma cell-free DNA for cancer detection and classification

Background

Targeted methylation sequencing of plasma cell-free DNA (cfDNA) has a potential to expand liquid biopsies to patients with tumors without detectable oncogenic alterations, which can be potentially useful in early diagnosis.

Patients and methods

We developed a comprehensive methylation sequencing assay targeting 9223 CpG sites consistently hypermethylated according to The Cancer Genome Atlas. Next, we carried out a clinical validation of our method using plasma cfDNA samples from 78 patients with advanced colorectal cancer, non-small-cell lung cancer (NSCLC), breast cancer or melanoma and compared results with patients' outcomes.

Results

Median methylation scores in plasma cfDNA samples from patients on therapy were lower than from patients off therapy (4.74 versus 85.29; P = 0.001). Of 68 plasma samples from patients off therapy, methylation scores detected the presence of cancer in 57 (83.8%), and methylation-based signatures accurately classified the underlying cancer type in 45 (78.9%) of these. Methylation scores were most accurate in detecting colorectal cancer (96.3%), followed by breast cancer (91.7%), melanoma (81.8%) and NSCLC (61.1%), and most accurate in classifying the underlying cancer type in colorectal cancer (88.5%), followed by NSCLC (81.8%), breast cancer (72.7%) and melanoma (55.6%). Low methylation scores versus high were associated with longer survival (10.4 versus 4.4 months, P < 0.001) and longer time-to-treatment failure (2.8 versus 1.6 months, P = 0.016).

Conclusions

Comprehensive targeted methylation sequencing of 9223 CpG sites in plasma cfDNA from patients with common advanced cancers detects the presence of cancer and underlying cancer type with high accuracy. Methylation scores in plasma cfDNA correspond with treatment outcomes.

Genomic characterization of HER2-positive breast cancer and response to neoadjuvant trastuzumab and chemotherapy-results from the ACOSOG Z1041 (Alliance) trial

Background

HER2 (ERBB2) gene amplification and its corresponding overexpression are present in 15-30% of invasive breast cancers. While HER2-targeted agents are effective treatments, resistance remains a major cause of death. The American College of Surgeons Oncology Group Z1041 trial (NCT00513292) was designed to compare the pathologic complete response (pCR) rate of distinct regimens of neoadjuvant chemotherapy and trastuzumab, but ultimately identified no difference.

Patients and methods

In supplement to tissues from 37 Z1041 cases, 11 similarly treated cases were obtained from a single institution study (NCT00353483). We have extracted genomic DNA from both pre-treatment tumor biopsies and blood of these 48 cases, and performed whole genome (WGS) and exome sequencing. Coincident with these efforts, we have generated RNA-seq profiles from 42 of the tumor biopsies. Among patients in this cohort, 24 (50%) achieved a pCR.

Results

We have characterized the genomic landscape of HER2-positive breast cancer and investigated associations between genomic features and pCR. Cases assigned to the HER2-enriched subtype by RNA-seq analysis were more likely to achieve a pCR compared to the luminal, basal-like, or normal-like subtypes (19/27 versus 3/15; P = 0.0032). Mutational events led to the generation of putatively active neoantigens, but were overall not associated with pCR. ERBB2 and GRB7 were the genes most commonly observed in fusion events, and genomic copy number analysis of the ERBB2 locus indicated that cases with either no observable or low-level ERBB2 amplification were less likely to achieve a pCR (7/8 versus 17/40; P = 0.048). Moreover, among cases that achieved a pCR, tumors consistently expressed immune signatures that may contribute to therapeutic response.

Conclusion

The identification of these features suggests that it may be possible to predict, at the time of diagnosis, those HER2-positive breast cancer patients who will not respond to treatment with chemotherapy and trastuzumab.

ClinicalTrials.gov identifiers

NCT00513292, NCT00353483.

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 P3-07-04: EphA2: An emerging target in triple-negative breast cancer

Purpose: Breast tumors classified as 'triple negative' (TNBC) lack defining markers ER/PR/HER2 and do not have clinically-approved targeted therapy. This heterogeneous classification of breast cancers, while immediately responsive to standard chemotherapy, commonly develop resistance and have a poor five-year survival rate. As such, the identification of new therapeutic targets are warranted. As part of our drug discovery platform, we have identified EphA2, as a synthetic-lethal gene that enhances the therapeutic action of FDA-approved, anti-inflammatory compounds. Thus we sought to ascertain the relevance of EphA2-targeted therapy in TNBC, through the evaluation of the marker in preclinical and clinical specimens.

Methods: Sixty-one human and murine breast cancer cell lines or patient-derived xenografts were collated. Protein lysates were created from cells in vitro or from respective tumors established from cells implanted into NSG mice. Forty-nine tumors established (minimum 500mm3) and were surgically removed, fixed in formalin and paraffin embedded. A TMA was constructed with tumor specimens represented twice on the array and reflected all molecular subtypes including; ER-positive (n=5), PR-positive (n=3), HER2-positive (n=9) and TNBC (n=31). Immunostaining for EphA2 was performed with the rabbit monoclonal antibody EphA2 (D4A2) XP (Cell Signaling, #6997) using manufacturer's instructions. Immunostaining was evaluated using the H-score method (score between 0-300), with positive staining for EphA2 reflecting a score of 100 or greater. Analysis of breast cancer lysates by western blot was analyzed by absolute and relative quantitation methods; gene expression data was assessed through Oncomine or using the BreastMark algorithm (http://glados.ucd.ie/BreastMark/). This algorithm integrates gene expression and survival data from 26 datasets on 12 different microarray platforms corresponding to ˜17,000 genes in up to 4,738 samples.

Results: In an integrated gene expression platform (BreastMark), we observed that elevated EphA2 expression was associated with poor prognosis in a cohort of TNBC patient tumor samples. Western blot analysis of EphA2 protein on breast cancer cell lines, identified a greater percentage of TNBC cells expressing EphA2 compared to non-TNBC cell lines. EphA2 immunostaining was observed in the majority of tumor tissues. When present on cancer cells, EphA2 localized to the cell surface; while displaying ubiquitous localization within stromal populations. Cell surface expression of EphA2 on cancer cells was largely restricted to TNBC tumors (11/31 tumors, 35.5%) compared to other molecular subtypes (1/13 non-TNBC tumors, 7.7%; p = 0.0294). Expression of EphA2 in stromal cell populations was similar between groups (TNBC = 22/31, non-TNBC = 11/13; p = 0.1711).

Conclusions: Our analysis determined that EphA2 was specifically expressed on cancer cells derived from tumors with a 'triple-negative' molecular subtype. Collectively our data suggests that EphA2 is an emerging target in TNBC and that therapies directed against EphA2 may provide a significant benefit for a majority of patients that express this marker.

Citation Format: Eckhardt BL, Torres AM, Woodward WA, Krishnamurthy S, Meric-Bernstam F, Ueno NT. EphA2: An emerging target 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 P3-07-04.

Abstract P3-04-01: Molecular determinants of post-mastectomy breast cancer recurrence

Introduction

The management of breast cancer (BC) patients who undergo mastectomy in the setting of 1-3 positive lymph nodes has been controversial. This retrospective Translational Breast Cancer Research Consortium study evaluated the molecular aberrations associated with locoregional recurrence (LRR) or distant metastasis (DM) compared to controls in an effort to identify molecular predictors associated with recurrence.

Methods/Materials

We identified 115 HER2 negative, therapy naïve, T 1-3 and N 0-1 BC patients treated with mastectomy and no post mastectomy radiation therapy from 1997 to present with available FFPE tissue blocks. The cohort included 32 patients with LRR, 34 with DM, and 49 controls (without recurrence) who were matched for stage, grade, hormone receptor status, age ≤ or &gt; 50, chemotherapy receipt, and margin status. Matched primary and recurrent LRR samples were available for 3 patients. Hybrid capture next generation sequencing (NGS) of 142 cancer related genes and RNAseq were performed to identify DNA/RNA alterations associated with LRR or DM. The frequency of common alterations on NGS was compared with Fisher's exact test. Expression of each gene from mRNA-Seq was treated as an explanatory variable. Immunohistochemistry (IHC) was performed for PTEN, Ki-67 and cleaved caspase 3 (CC3). PTEN loss and percentage of Ki-67 and CC3 positive cells were compared between groups with Fisher's exact test and nonparametric methods, respectively.

Results

RNAseq was performed on 115 patients; there was no difference in RNA expression levels between the groups. DNA analysis was performed on 57 patients (17 LRR, 15 DM and 25 controls), NF1 mutation rate was significantly elevated in both the LRR (24%) and DM (27%) samples compared to controls 0%; (p=0.0070). The mitogen activated protein kinase (MAPK) pathway was significantly mutated in both LRR (47%) and DM (40%) samples compared to the controls 0%; (p&lt;0.0001). There was no significant difference in the rate of alterations of the PI3K/Akt/mTOR pathway among the three groups. Of three patients with matched primary vs LRR samples, one had concordant mutations. The second patient had additional mutations in the LRR, including gain of a NF1 mutation. The third patient had complete discordance of mutations identified in primary and LRR and had gain of HER2 amplification, suggestive of a new primary. There was no significant association between the groups and the loss of PTEN expression or CC3 expression. There was a significant difference between Ki 67 positive cells in patients with LRR (mean 29%), DM (mean 26%) versus controls (mean 14%, p= 0.0011). HR+ patients were significantly more likely to have a positive PTEN, lower Ki-67 and lower CC3 expression, p=0.0004, p&lt;0.0001, and p&lt;0.0001 respectively.

Conclusions

In this matched cohort analysis, mutations in the MAPK pathway, specifically NF1, were associated with both LRR and DM, suggesting that alterations in this pathway are associated with a more aggressive tumor phenotype. However, there were no molecular features that discriminated between those likely to recur locally alone versus distantly. Further study is needed to validate these findings, and to determine whether targeting alterations in this pathway could decrease the risk of recurrence.

Citation Format: Keene KS, King T, Hwang ES, Peng B, McGuire K, Tapia C, Zhang H, Bae S, Nakhlis F, Klauber-Demore N, Meszoely I, Sabel MS, Willey SC, Eterovic KA, Hudis C, Wolff A, De Los Santos J, Thompson A, Mills GB, Meric-Bernstam F. Molecular determinants of post-mastectomy breast cancer recurrence [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 P3-04-01.

Abstract P5-20-06: Phase 1 dose escalation with ZW25, a HER2-targeted bispecific antibody, in patients (pts) with HER2-high breast cancer (BC)

Background: ZW25, a novel IgG1-like bispecific antibody, targets the same domains of HER2 as trastuzumab (T) and pertuzumab (P). In preclinical studies, ZW25 demonstrated increased tumor cell binding density and internalization relative to T and activity in T-resistant cell lines as well as models of HER2-low to high cancers. Initial dose escalation data demonstrated that once-weekly ZW25 was well tolerated at all doses evaluated and associated with single-agent anti-tumor activity in pts with heavily pre-treated (tx) HER2-expressing cancers.

Methods: 3+3 dose escalation of ZW25 given weekly (QW; 5, 10 or 15 mg/kg) or biweekly (Q2W; 20 mg/kg) in 4-week cycles. Eligibility included HER2 IHC 1, 2 or 3+ or FISH+ BC, progression after T, P and T-DM1, and measurable or non-measureable disease per RECIST 1.1. Active brain metastases were excluded. Baseline brain MRI was performed in QW cohorts only if pts had prior history (hx) of CNS mets, and in all Q2W pts regardless of hx. Assessments included AEs, LVEF, immunogenicity, PK and tumor response every 2 cycles.

Results: 8 pts with HER2-high BC were tx with ZW25 QW at 5 (n=2), 10 (n=2) or 15 mg/kg (n=4); 20 mg/kg Q2W is enrolling. 5/8 pts were HR+; 7 had measurable disease, 6 visceral disease, and 3 stable CNS disease. Median years since initial dx was 6 (range 5-16). Prior tx included T and T-DM1 (n=8); P (n= 6), and lapatinib (n=5). Median number of prior HER2-targeted regimens for metastatic disease was 6 (range 3-7) and non-hormonal HER2 regimens was 5 (range 3-7).

ZW25 was well tolerated with no DLTs or decreases in cardiac function. Most common related AEs (all Gr 1 or 2) were diarrhea (n=4), infusion reaction (IR) (n=4) and vomiting (n=3). All IRs occurred only with 1st dose. There were no treatment-related SAEs. Related Gr 3 AEs (hypophosphatemia, fatigue and arthralgia) were reported in 1 pt (10 mg/kg).

At data cut-off, pts had received 2-10 cycles of treatment, with 3 pts active. Best overall response was 2 PR (10 mg/kg), 3 SD (1 at 5 mg/kg, 2 at 15 mg/kg), and 3 PD (1 at 5 mg/kg, 2 at 15 mg/kg) for a disease control rate of 63%. Decreases in target lesions were seen in 6/7 patients with at least one tumor re-staging. One pt with SD (5 mg/kg; active on study) had an 8% decrease after C2, and 29% decrease after C8. One PR pt with prior hx of brain mets had a 33% decrease after C2 and 44% decrease after C4, although was found to have new leptomeningeal disease (LMD) at that time. Two additional pts with systemic SD (15 mg/kg; no prior hx of CNS mets) were also considered to have PD due to symptomatic brain mets. One of these pts remains on study after receiving stereotactic radiotherapy.

Conclusions: ZW25 was associated with single-agent anti-tumor activity and systemic disease control in HER2-high BC pts after a median of 6 prior HER2-targeted regimens for metastatic disease. Systemic disease control was maintained despite PD due to brain mets or LMD. The presence of CNS disease in an unscreened population is consistent with the biology of late-stage HER2-high BC. The activity and tolerability of ZW25 support further evaluation as a single agent and in combination including with CNS-directed therapies in early and late lines of treatment for HER2-expressing BC.

Citation Format: Hamilton E, Meric-Bernstam F, Infante J, Murthy R, Patnaik A, Piha-Paul SA, Tolcher A, Hausman D, Royer N, Beeram M. Phase 1 dose escalation with ZW25, a HER2-targeted bispecific antibody, in patients (pts) with HER2-high breast cancer (BC) [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 P5-20-06.

Vertical inhibition of the PI3K/Akt/mTOR pathway is synergistic in breast cancer

Deregulation and activation of the phosphoinositide 3-kinase (PI3K)/Akt/mammalian (or mechanistic) target of rapamycin (mTOR) pathway have a major role in proliferation and cell survival in breast cancer. However, as single agents, mTOR inhibitors have had modest antitumor efficacy. In this study, we evaluated the effects of vertical inhibition of mTOR and Akt in breast cancer cell lines and xenografts. We assessed the effects of mTOR inhibitor rapamycin and Akt inhibitor MK-2206, given as single drugs or in combination, on cell signaling, cell proliferation and apoptosis in a panel of cancer cell lines in vitro. The antitumor efficacy was tested in vivo. We demonstrated that MK-2206 inhibited Akt phosphorylation, cell proliferation and apoptosis in a dose-dependent manner in breast cancer cell lines. Rapamycin inhibited S6 phosphorylation and cell proliferation, and resulted in lower levels of apoptosis induction. Furthermore, the combination treatment inhibited phosphorylation of Akt and S6, synergistically inhibited proliferation and induced apoptosis with a higher efficacy. In vivo combination inhibited tumor growth more than either agent alone. Our data suggest that a combination of Akt and mTOR inhibitors have greater antitumor activity in breast cancer cells, which may be a viable approach to treat patients.

High prevalence of mutant KRAS in circulating exosome-derived DNA from early-stage pancreatic cancer patients

Background

Exosomes arise from viable cancer cells and may reflect a different biology than circulating cell-free DNA (cfDNA) shed from dying tissues. We compare exosome-derived DNA (exoDNA) to cfDNA in liquid biopsies of patients with pancreatic ductal adenocarcinoma (PDAC).

Patients and methods

Patient samples were obtained between 2003 and 2010, with clinically annotated follow up to 2015. Droplet digital PCR was performed on exoDNA and cfDNA for sensitive detection of KRAS mutants at codons 12/13. A cumulative series of 263 individuals were studied, including a discovery cohort of 142 individuals: 68 PDAC patients of all stages; 20 PDAC patients initially staged with localized disease, with blood drawn after resection for curative intent; and 54 age-matched healthy controls. A validation cohort of 121 individuals (39 cancer patients and 82 healthy controls) was studied to validate KRAS detection rates in early-stage PDAC patients. Primary outcome was circulating KRAS status as detected by droplet digital PCR. Secondary outcomes were disease-free and overall survival.

Results

KRAS mutations in exoDNA, were identified in 7.4%, 66.7%, 80%, and 85% of age-matched controls, localized, locally advanced, and metastatic PDAC patients, respectively. Comparatively, mutant KRAS cfDNA was detected in 14.8%, 45.5%, 30.8%, and 57.9% of these individuals. Higher exoKRAS MAFs were associated with decreased disease-free survival in patients with localized disease. In the validation cohort, mutant KRAS exoDNA was detected in 43.6% of early-stage PDAC patients and 20% of healthy controls.

Conclusions

Exosomes are a distinct source of tumor DNA that may be complementary to other liquid biopsy DNA sources. A higher percentage of patients with localized PDAC exhibited detectable KRAS mutations in exoDNA than previously reported for cfDNA. A substantial minority of healthy samples demonstrated mutant KRAS in circulation, dictating careful consideration and application of liquid biopsy findings, which may limit its utility as a broad cancer-screening method.

Multiplex KRASG12/G13 mutation testing of unamplified cell-free DNA from the plasma of patients with advanced cancers using droplet digital polymerase chain reaction

Background

Cell-free DNA (cfDNA) from plasma offers easily obtainable material for KRAS mutation analysis. Novel, multiplex, and accurate diagnostic systems using small amounts of DNA are needed to further the use of plasma cfDNA testing in personalized therapy.

Patients and methods

Samples of 16 ng of unamplified plasma cfDNA from 121 patients with diverse progressing advanced cancers were tested with a KRASG12/G13 multiplex assay to detect the seven most common mutations in the hotspot of exon 2 using droplet digital polymerase chain reaction (ddPCR). The results were retrospectively compared to mutation analysis of archival primary or metastatic tumor tissue obtained at different points of clinical care.

Results

Eighty-eight patients (73%) had KRASG12/G13 mutations in archival tumor specimens collected on average 18.5 months before plasma analysis, and 78 patients (64%) had KRASG12/G13 mutations in plasma cfDNA samples. The two methods had initial overall agreement in 103 (85%) patients (kappa, 0.66; ddPCR sensitivity, 84%; ddPCR specificity, 88%). Of the 18 discordant cases, 12 (67%) were resolved by increasing the amount of cfDNA, using mutation-specific probes, or re-testing the tumor tissue, yielding overall agreement in 115 patients (95%; kappa 0.87; ddPCR sensitivity, 96%; ddPCR specificity, 94%). The presence of ≥ 6.2% of KRASG12/G13 cfDNA in the wild-type background was associated with shorter survival (P = 0.001).

Conclusion(s)

Multiplex detection of KRASG12/G13 mutations in a small amount of unamplified plasma cfDNA using ddPCR has good sensitivity and specificity and good concordance with conventional clinical mutation testing of archival specimens. A higher percentage of mutant KRASG12/G13 in cfDNA corresponded with shorter survival.

Abstract P2-01-05: A phase II clinical trial of VST-1001 (dilute fluorescein) in lymphatic mapping and sentinel lymph node localization in clinically node negative breast cancer

Background: Combined use of a radiocolloid and a vital blue dye is recommended for accurate lymphatic mapping and sentinel lymph node (SLN) identification in breast cancer. However, vital blue dyes can cause tattooing, skin necrosis and severe allergic reactions. Moreover, the vital blue dyes are only able to detect 70% or less of SLNs in large multi-center trials. Hence, there is an unmet need to develop new lymphatic mapping agents that could potentially replace vital blue dyes. We have previously, in a Phase I trial, reported on the safety of VST-1001 (dilute fluorescein) in SLN identification. Here we report the Phase II data of VST-1001 and direct visualization devices in lymphatic mapping, SLN identification, and safety in clinically node negative breast cancer.

Methods: This prospective Phase II, multi-center, non-randomized, single-arm, open-label, single-dose clinical trial enrolled patients (pts) with DCIS and clinical stage I/II breast cancer eligible for SLN biopsy. All pts had SLN localization with technetium-99m-sulfur colloid (Tc99mSC) and intraoperative lymphatic mapping with 0.1% VST-1001 injected peritumorally, periareolarly, and/or intradermally. SLN radioactivity was identified with a gamma probe, and VST-1001 fluorescence was induced by light emitting diodes and detected as yellowish-green fluorescence in the visible light range with notch filter spectacles. The primary endpoint was the ability of VST-1001 to localize lymph nodes. SLN concordance of Tc99mSC radioactivity and VST-1001 fluorescence, and safety were also assessed.

Results: Eighty-seven women and 2 men with a median age of 60 yrs (range, 37-77) were enrolled. Primary tumor T-stage was: 12.4% T0, 62.9% T1, 23.6% T2, and 1.1% T3. Of the 89 pts, 87 (97.8%) had at least 1 radioactive SLN, and 86 (96.6%) at least 1 fluorescent SLN. Of a total of 198 SLN identified (mean 2.2 SLN/pt), 74.2% were fluorescent and radioactive, 11.6% were radioactive only, 8.6% were fluorescent only, and 5.1% were not radioactive or fluorescent. 82.8% of all SLNs were fluorescent. Twelve (13.5%) pts had microscopic metastatic breast cancer in 14 (7.1%) SLNs. Of the 14 SLNs with metastasis, 12 (85.7%) were both radioactive and fluorescent, 1 (7.1%) fluorescent only and 1 (7.1%) not radioactive or fluorescent and only suspicious on palpation. The fluorescent only SLN was identified in a patient with only 1 SLN and without VST-1001 the metastasis would have been missed. The only adverse event related to VST-1001 was intraoperative grade 2 allergic reaction of the ipsilateral breast in one pt. Intravenous anti-histamines were administered and the erythema resolved.

Conclusions: VST-1001 safely localized lymph nodes in breast cancer. VST-1001 was able to localize lymph nodes that were not radioactive and had a high co-localization concordance with Tc99mSC. VST-1001 also appears to have a higher rate of SLN localization compared to that historically reported for vital blue dyes. In light of these data, VST-1001 may be an alternative SLN localizing agent to be used in conjunction with Tc99mSC in breast cancer pts, eliminating many of adverse events observed when using vital blue dyes without compromising SLN identification.

Citation Format: Ross MI, Black DM, Mittendorf EA, Porretta JM, Bedrosian I, Caudle AS, Hwang RF, Meric-Bernstam F, Babiera GV, Brulotte M, Andtbacka RHI, Matsen CB. A phase II clinical trial of VST-1001 (dilute fluorescein) in lymphatic mapping and sentinel lymph node localization in clinically node negative 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 P2-01-05.

Ribociclib plus letrozole in early breast cancer: A presurgical, window-of-opportunity study

OBJECTIVES

Cyclin D-cyclin-dependent kinase (CDK) 4/6-inhibitor of CDK4/6-retinoblastoma (Rb) pathway hyperactivation is associated with hormone receptor-positive (HR+) breast cancer (BC). This study assessed the biological activity of ribociclib (LEE011; CDK4/6 inhibitor) plus letrozole compared with single-agent letrozole in the presurgical setting.

MATERIALS AND METHODS

Postmenopausal women (N = 14) with resectable, HR+, human epidermal growth factor receptor 2-negative (HER2-) early BC were randomized 1:1:1 to receive 2.5 mg/day letrozole alone (Arm 1), or with 400 or 600 mg/day ribociclib (Arm 2 or 3). Circulating tumor DNA and tumor biopsies were collected at baseline and, following 14 days of treatment, prior to or during surgery. The primary objective was to assess antiproliferative response per Ki67 levels in Arms 2 and 3 compared with Arm 1. Additional assessments included safety, pharmacokinetics, and genetic profiling.

RESULTS

Mean decreases in the Ki67-positive cell fraction from baseline were: Arm 1 69% (range 38-100%; n = 2), Arm 2 96% (range 78-100%; n = 6), Arm 3 92% (range 75-100%; n = 3). Decreased phosphorylated Rb levels and CDK4, CDK6, CCND2, CCND3, and CCNE1 gene expression were observed following ribociclib treatment. Ribociclib and letrozole pharmacokinetic parameters were consistent with single-agent data. The ribociclib plus letrozole combination was well tolerated, with no Grade 3/4 adverse events over the treatment.

CONCLUSION

The results suggest absence of a drug-drug interaction between ribociclib and letrozole and indicate ribociclib plus letrozole may reduce Ki67 expression in HR+, HER2- BC (NCT01919229).

Utility of a molecular prescreening program in advanced colorectal cancer for enrollment on biomarker-selected clinical trials

BACKGROUND

Incorporation of multiple enrichment biomarkers into prospective clinical trials is an active area of investigation, but the factors that determine clinical trial enrollment following a molecular prescreening program have not been assessed.

PATIENTS AND METHODS

Patients with 5-fluorouracil-refractory metastatic colorectal cancer at the MD Anderson Cancer Center were offered screening in the Assessment of Targeted Therapies Against Colorectal Cancer (ATTACC) program to identify eligibility for companion phase I or II clinical trials with a therapy targeted to an aberration detected in the patient, based on testing by immunohistochemistry, targeted gene sequencing panels, and CpG island methylation phenotype assays.

RESULTS

Between August 2010 and December 2013, 484 patients were enrolled, 458 (95%) had a biomarker result, and 157 (32%) were enrolled on a clinical trial (92 on biomarker-selected and 65 on nonbiomarker selected). Of the 458 patients with a biomarker result, enrollment on biomarker-selected clinical trials was ninefold higher for predefined ATTACC-companion clinical trials as opposed to nonpredefined biomarker-selected clinical trials, 17.9% versus 2%, P < 0.001. Factors that correlated positively with trial enrollment in multivariate analysis were higher performance status, older age, lack of standard of care therapy, established patient at MD Anderson, and the presence of an eligible biomarker for an ATTACC-companion study. Early molecular screening did result in a higher rate of patients with remaining standard of care therapy enrolling on ATTACC-companion clinical trials, 45.1%, in contrast to nonpredefined clinical trials, 22.7%; odds ratio 3.1, P = 0.002.

CONCLUSIONS

Though early molecular prescreening for predefined clinical trials resulted in an increase rate of trial enrollment of nonrefractory patients, the majority of patients enrolled on clinical trials were refractory to standard of care therapy. Within molecular prescreening programs, tailoring screening for preidentified and open clinical trials, temporally linking screening to treatment and optimizing both patient and physician engagement are efforts likely to improve enrollment on biomarker-selected clinical trials.

CLINICAL TRIALS NUMBER

The study NCT number is NCT01196130.