NSABP FB-10: a phase Ib/II trial evaluating ado-trastuzumab emtansine (T-DM1) with neratinib in women with metastatic HER2-positive breast cancer

BACKGROUND

We previously reported our phase Ib trial, testing the safety, tolerability, and efficacy of T-DM1 + neratinib in HER2-positive metastatic breast cancer patients. Patients with ERBB2 amplification in ctDNA had deeper and more durable responses. This study extends these observations with in-depth analysis of molecular markers and mechanisms of resistance in additional patients.

METHODS

Forty-nine HER2-positive patients (determined locally) who progressed on-treatment with trastuzumab + pertuzumab were enrolled in this phase Ib/II study. Mutations and HER2 amplifications were assessed in ctDNA before (C1D1) and on-treatment (C2D1) with the Guardant360 assay. Archived tissue (TP0) and study entry biopsies (TP1) were assayed for whole transcriptome, HER2 copy number, and mutations, with Ampli-Seq, and centrally for HER2 with CLIA assays. Patient responses were assessed with RECIST v1.1, and Molecular Response with the Guardant360 Response algorithm.

RESULTS

The ORR in phase II was 7/22 (32%), which included all patients who had at least one dose of study therapy. In phase I, the ORR was 12/19 (63%), which included only patients who were considered evaluable, having received their first scan at 6 weeks. Central confirmation of HER2-positivity was found in 83% (30/36) of the TP0 samples. HER2-amplified ctDNA was found at C1D1 in 48% (20/42) of samples. Patients with ctHER2-amp versus non-amplified HER2 ctDNA determined in C1D1 ctDNA had a longer median progression-free survival (PFS): 480 days versus 60 days (P = 0.015). Molecular Response scores were significantly associated with both PFS (HR 0.28, 0.09-0.90, P = 0.033) and best response (P = 0.037). All five of the patients with ctHER2-amp at C1D1 who had undetectable ctDNA after study therapy had an objective response. Patients whose ctHER2-amp decreased on-treatment had better outcomes than patients whose ctHER2-amp remained unchanged. HER2 RNA levels show a correlation to HER2 CLIA IHC status and were significantly higher in patients with clinically documented responses compared to patients with progressive disease (P = 0.03).

CONCLUSIONS

The following biomarkers were associated with better outcomes for patients treated with T-DM1 + neratinib: (1) ctHER2-amp (C1D1) or in TP1; (2) Molecular Response scores; (3) loss of detectable ctDNA; (4) RNA levels of HER2; and (5) on-treatment loss of detectable ctHER2-amp. HER2 transcriptional and IHC/FISH status identify HER2-low cases (IHC 1+ or IHC 2+ and FISH negative) in these heavily anti-HER2 treated patients. Due to the small number of patients and samples in this study, the associations we have shown are for hypothesis generation only and remain to be validated in future studies. Clinical Trials registration NCT02236000.

Long-Term Follow-Up of the Anthracyclines in Early Breast Cancer Trials (USOR 06-090, NSABP B-46-I/USOR 07132, and NSABP B-49 [NRG Oncology])

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The primary joint efficacy analysis of the Anthracyclines in Early Breast Cancer (ABC) trials reported in 2017 failed to demonstrate nonanthracycline adjuvant therapy was noninferior to anthracycline-based regimens in high-risk, early breast cancer. Full analyses of the studies had proceeded when the prespecified futility boundary was crossed at a planned futility analysis for the ability to demonstrate noninferiority of a nonanthracycline regimen with continued follow-up. These results were presented with 3.3 years of median follow-up. This manuscript reports results of the final analyses of the study efficacy end points conducted with 6.9 years of median follow-up. Long-term analysis of invasive disease-free survival (IDFS), the primary end point of the ABC trials, remains consistent with the original results, as noninferiority of the nonanthracycline regimens could not be declared on the basis of the original criteria. The secondary end point of recurrence-free interval, which excluded deaths not due to breast cancer as events, favored anthracycline-based regimens, and tests for heterogeneity were significant for hormone receptor status (P = .02) favoring anthracycline regimens for the hormone receptor-negative cohorts. There was no difference in overall survival, and review of the type of IDFS events in the groups suggested reductions in cancer recurrences achieved with anthracycline regimens were offset by late leukemias and deaths unrelated to breast cancer.

Veliparib with carboplatin and paclitaxel in BRCA-mutated advanced breast cancer (BROCADE3): Final overall survival results from a randomized phase 3 trial

BACKGROUND

In the BROCADE3 study, the addition of veliparib to carboplatin plus paclitaxel resulted in a significant improvement in progression-free survival (PFS) compared with placebo plus carboplatin and paclitaxel, in patients with germline BRCA1 or BRCA2 (BRCA1/2)-mutated, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. We now report final overall survival (OS) data.

METHODS

BROCADE3 is a randomized phase 3 study that enrolled patients with BRCA1/2-mutated, HER2-negative advanced breast cancer who received ≤ 2 prior lines of chemotherapy for metastatic disease. Patients were randomized 2:1 to carboplatin and paclitaxel, dosed with either veliparib or matching placebo. OS was a secondary endpoint.

RESULTS

In the intention-to-treat population (N = 509), 337 patients were randomized to receive veliparib and 172 to placebo. Median OS was 32.4 months vs 28.2 months (hazard ratio, 0.916; 95% CI, 0.736-1.140; P = .434). The updated safety data for veliparib are consistent with those reported in the primary analysis; the addition of veliparib was generally well tolerated.

CONCLUSIONS

Final OS data indicate that the PFS improvement shown in the primary analysis did not translate into an OS benefit. The long survival times observed in both arms suggest that combination therapy with paclitaxel and carboplatin provides clinical benefit in the population of patients with BRCA1/2-mutated metastatic breast cancer.

WCRC-25: A novel luminal Invasive Lobular Carcinoma cell line model

Breast cancer is categorized by the molecular and histologic presentation of the tumor, with the major histologic subtypes being No Special Type (NST) and Invasive Lobular Carcinoma (ILC). ILC are characterized by growth in a single file discohesive manner with stromal infiltration attributed to their hallmark pathognomonic loss of E-cadherin ( CDH1 ). Few ILC cell line models are available to researchers. Here we report the successful establishment and characterization of a novel ILC cell line, WCRC-25, from a metastatic pleural effusion from a postmenopausal Caucasian woman with metastatic ILC. WCRC-25 is an ER-negative luminal epithelial ILC cell line with both luminal and Her2-like features. It exhibits anchorage independent growth and haptotactic migration towards Collagen I. Sequencing revealed a CDH1 Q706* truncating mutation, together with mutations in FOXA1, CTCF, BRCA2 and TP53 , which were also seen in a series of metastatic lesions from the patient. Copy number analyses revealed amplification and deletion of genes frequently altered in ILC while optical genome mapping revealed novel structural rearrangements. RNA-seq analysis comparing the primary tumor, metastases and the cell line revealed signatures for cell cycle progression and receptor tyrosine kinase signaling. To assess targetability, we treated WCRC-25 with AZD5363 and Alpelisib confirming WCRC-25 as susceptible to PI3K/AKT signaling inhibition as predicted by our RNA sequencing analysis. In conclusion, we report WCRC-25 as a novel ILC cell line with promise as a valuable research tool to advance our understanding of ILC and its therapeutic vulnerabilities.

Financial support

The work was in part supported by a Susan G Komen Leadership Grant to SO (SAC160073) and NCI R01 CA252378 (SO/AVL). AVL and SO are Komen Scholars, Hillman Foundation Fellows and supported by BCRF. This project used the UPMC Hillman Cancer Center and Tissue and Research Pathology/Pitt Biospecimen Core shared resource which is supported in part by award P30CA047904. This research was also supported in part by the University of Pittsburgh Center for Research Computing, RRID:SCR_022735, through the resources provided. Specifically, this work used the HTC cluster, which is supported by NIH award number S10OD028483. Finally, partial support was provided by the Magee-Womens Research Institute and Foundation, The Shear Family Foundation, and The Metastatic Breast Cancer Network.

NSABP C-14: CORRECT-MRD II—Second colorectal cancer clinical validation study to predict recurrence using a circulating tumor DNA assay to detect minimal residual disease

TPS284

Background: Detectable ctDNA after resection of early-stage solid tumors has been associated with very high risk of recurrence, suggesting ctDNA is evidence of minimal residual disease (MRD). Several studies are ongoing to investigate the role of ctDNA in the optimal management of pts with colorectal cancer using different assay technologies. Methods: This is a prospective, observational, multicenter study in the United States and Canada of 750 patients who have undergone complete surgical resection for stage II or III colorectal cancer, who have FFPE tissue available from the primary resection sufficient for a novel bespoke MRD assay and are willing to provide serial whole blood specimens for ctDNA analysis. Participants are asked to provide study specimens after definitive surgical resection, pre-recurrence follow-up, and clinical recurrence (if applicable). Recently amended eligibility criteria include inclusion of rectal cancer patients who have completed neo-adjuvant therapy and surgical resection, as well as enrollment of all stage II and III patients regardless of microsatellite stability status. The Oncotype Colon Recurrence Score will be assessed on all patients from their surgical specimen if criteria are met for this testing. ctDNA will be analyzed with an NGS-based tumor-informed MRD assay that identifies somatic genomic alterations from DNA derived from the patient’s tumor tissue, subtracts germline variants, and detects a selected subset of tumor-specific (bespoke) ctDNA in their blood. All primary tumor specimens will undergo full exome and transcriptome sequencing using the Oncomap ExTra assay. If there is evidence of disease recurrence, the metastatic tissue will also undergo Oncomap ExTra testing, which will be shared with participants. The primary objective is to validate the association of post-definitive therapy and pre-recurrence follow-up ctDNA positivity with recurrence-free interval (RFI). Further objectives are to assess the: sensitivity and specificity of ctDNA positivity for subsequent clinical recurrence; contribution of post-surgery baseline, post-adjuvant therapy, and pre-recurrence follow-up ctDNA results on RFI; time from positive ctDNA to clinical recurrence in participants who had a positive ctDNA result; and compare the Oncotype Colon Recurrence Score estimate of 3-year recurrence risk with the observed 3-year recurrence rate. The primary analysis will use a Cox proportional hazards regression applied to the RFI with ctDNA result (positive or negative) measured at post-surgical baseline (or end of adjuvant therapy if used) and serially after that as a single, time-dependent covariate. Protocol#: NSABP C-14 / ES 16-002. Support: NSABP Foundation, ExactSciences Clinical trial information: 05210283 .

Cisplatin with veliparib or placebo in metastatic triple-negative breast cancer and BRCA mutation-associated breast cancer (S1416): a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Poly(ADP-ribose) polymerase (PARP) inhibitors are effective in germline BRCA1 or BRCA2 (BRCA1/2) mutation-associated metastatic breast cancer. However, studies evaluating PARP inhibitors plus platinum-based chemotherapy in germline BRCA1/2-wildtype triple-negative breast cancer are scarce. A large proportion of germline BRCA1/2-wildtype triple-negative breast cancer shows homologous recombination deficiency (HRD), resulting in a BRCA-like phenotype that might render sensitivity to PARP inhibitors. The S1416 trial assessed the efficacy of cisplatin combined with the PARP inhibitor veliparib in three predefined groups of metastatic breast cancer: germline BRCA1/2-mutated, BRCA-like, and non-BRCA-like.

METHODS

S1416 was a randomised, double-blind, placebo-controlled, phase 2 trial conducted at 154 community and academic clinical sites across the USA. Eligible patients aged 18 years or older had metastatic or recurrent triple-negative breast cancer or germline BRCA1/2-associated metastatic or recurrent breast cancer, an Eastern Cooperative Oncology Group performance status of 0-2, and had received up to one line of chemotherapy for metastatic disease. Patients were randomly assigned (1:1) via the National Clinical Trials Network open interactive system with dynamic balancing on number of previous cytotoxic regimens for metastatic disease to receive intravenous cisplatin (75 mg/m2, day 1) combined with either veliparib or matching placebo (300 mg orally twice a day, days 1-14) on a 21-day cycle. Investigators, patients, and the sponsors were masked to treatment assignment; the study statisticians were unmasked. Central testing after ran domisation classified patients as having mutated or wildtype germline BRCA1/2. A biomarker panel established a priori was used to classify patients with wildtype germline BRCA1/2 into BRCA-like and non-BRCA-like phenotype groups, with BRCA-like status based on at least one of the biomarkers: genomic instability score (≥42), somatic BRCA1/2 mutations, BRCA1 promoter methylation, or non-BRCA1/2 homologous recombination repair germline mutations. The primary endpoint was investigator-assessed progression-free survival, analysed separately for the three predefined biomarker groups with a prespecified α value for each analysis. Efficacy analyses were done by intention to treat and included all eligible patients. Safety analyses of toxicities attributed to treatment included all patients who received at least one dose of veliparib or placebo. The study is ongoing and registered with ClinicalTrials.gov, NCT02595905.

FINDINGS

Between July 7, 2016, and June 15, 2019, 335 patients were enrolled and randomly assigned. 320 patients (n=162 to cisplatin plus veliparib, all women; and n=158 to cisplatin plus placebo, 157 women and one man) were eligible for efficacy evaluation. 247 patients were classified into the three biomarker groups: germline BRCA1/2-mutated (n=37), BRCA-like (n=101), and non-BRCA-like (n=109). 73 patients could not be classified due to missing biomarker information. Median follow-up was 11·1 months (IQR 5·6-20·8). In the germline BRCA1/2-mutated group, median progression-free survival was 6·2 months (95% CI 2·3-9·2) in the cisplatin plus veliparib group and 6·4 months (4·3-8·2) in the cisplatin plus placebo group (HR 0·79 [95% CI 0·38-1·67]; log-rank p=0·54). In the BRCA-like group, median progression-free survival was 5·9 months (95% CI 4·3-7·8) in the cisplatin plus veliparib group versus 4·2 months (2·3-5·0) in the cisplatin plus placebo group (HR 0·57 [95% CI 0·37-0·88]; p=0·010). In the non-BRCA-like group, median progression-free survival was 4·0 months (95% CI 2·5-4·7) in the cisplatin plus veliparib group versus 3·0 months (2·2-4·4) in the cisplatin plus placebo group (HR 0·89 [95% CI 0·60-1·33]; p=0·57). The most common grade 3 or worse adverse events attributed to treatment were neutropenia (71 [46%] of 155 patients in the cisplatin plus veliparib group vs 29 [20%] of 147 in the cisplatin plus placebo group), leukopenia (42 [27%] vs 11 [7%]), anaemia (35 [23%] vs 12 [8%]), and thrombocytopenia (29 [19%] vs four [3%]). Serious adverse events attributed to treatment occurred in 48 (31%) patients in the cisplatin plus veliparib group and 53 (36%) patients in the cisplatin plus placebo group. Treatment-related adverse events led to death in one patient in the cisplatin plus veliparib group (sepsis) and one patient in the cisplatin plus placebo group (acute kidney injury due to cisplatin plus heart failure from previous doxorubicin exposure).

INTERPRETATION

The addition of veliparib to cisplatin significantly improved progression-free survival in patients with BRCA-like metastatic triple-negative breast cancer, but not in patients with non-BRCA-like metastatic breast cancer. PARP inhibitors combined with platinum-based chemotherapy should be explored further in BRCA-like triple-negative breast cancer.

FUNDING

National Cancer Institute and National Institute of General Medical Sciences (US National Institutes of Health); AbbVie; Myriad Genetics; the Biomarker, Imaging, and Quality of Life Studies Funding Program (awarded by the National Cancer Institute); and The University of Kansas Cancer Center.

Abemaciclib in Combination With Endocrine Therapy for Patients With Hormone Receptor-Positive, HER2-Negative Metastatic Breast Cancer: A Phase 1b Study

Background

Cyclin-dependent kinases (CDK) 4 and 6 regulate G1 to S cell cycle progression and are often altered in cancers. Abemaciclib is a selective inhibitor of CDK4 and CDK6 approved for administration on a continuous dosing schedule as monotherapy or as combination therapy with an aromatase inhibitor or fulvestrant in patients with advanced or metastatic breast cancer. This Phase 1b study evaluated the safety and tolerability, pharmacokinetics, and antitumor activity of abemaciclib in combination with endocrine therapy for metastatic breast cancer (MBC), including aromatase inhibitors (letrozole, anastrozole, or exemestane) or tamoxifen.

Patients and Methods

Women ≥18 years old with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) MBC were eligible for enrollment. Eligibility included measurable disease or non-measurable but evaluable bone disease by Response Evaluation Criteria in Solid Tumours (RECIST) v1.1, Eastern Cooperative Oncology Group performance status 0–1, and no prior chemotherapy for metastatic disease. Adverse events were graded by the National Cancer Institute Common Terminology Criteria for Adverse Events v4.0 and tumor response were assessed by RECIST v1.1.

Results

Sixty-seven patients were enrolled and received abemaciclib 200 mg every 12 hours in combination with letrozole (Part A, n=20), anastrozole (Part B, n=16), tamoxifen (Part C, n=16), or exemestane (Part D, n=15). The most common treatment-emergent adverse events (TEAE) were diarrhea, fatigue, nausea, and abdominal pain. Grade 4 TEAEs were reported in five patients (one each with hyperglycemia, hypertension, neutropenia, procedural hemorrhage, and sepsis). There was no effect of abemaciclib or endocrine therapy on the pharmacokinetics of any combination study drug. Across all treated patients, the median progression-free survival was 25.4 months (95% confidence interval: 18.0, 35.8). The objective response rate was 38.9% in 36 patients with measurable disease.

Conclusions

Abemaciclib in combination with multiple endocrine therapy options exhibited manageable safety and promising antitumor activity in patients with HR+, HER2- MBC.

Clinical Trial Registration

https://clinicaltrials.gov/, identifier NCT02057133

Abstract P5-12-03: Wcrc-25: A novel luminal invasive lobular carcinoma cell line model

Breast cancer is categorized by the molecular and histologic presentation of the tumor; with the major histologic subtypes observed in patients being Invasive Ductal Carcinoma (IDC) and Invasive Lobular Carcinoma (ILC). ILC are characterized by growth in a single file discohesive manner with stromal infiltration attributed to their hallmark loss of E-cadherin. The lower incidence of ILC, relative to IDC, resulted in this subtype being understudied in the field. The Cancer Cell Line Encyclopedia (CCLE) currently only lists 2 ILC cell lines; emphasizing the need to expand the inventory of models available to researchers. To that end, here we report the successful establishment and characterization of a novel ILC cell line from a metastatic pleural aspirate from a postmenopausal Caucasian woman with ER+ metastatic ILC. The patient underwent a bilateral mastectomy, several pleural fluid aspirations and multiple treatment changes as her disease progressed until she succumbed to the disease. Various cell culture methods were attempted with the pleural aspirate and a standard practice of DMEM supplemented with 10% FBS in normoxic conditions was deemed effective. A cell line was developed, WCRC-25 which is ER-. WCRC-25 appears to be E2 unresponsive in vitro and is morphologically larger than other ILC cells currently in use, namely, MDA-MB-134, BCK4 and IPH-926, while exhibiting better adherence to 2D plates and a less rounded morphology. Sequencing revealed a CDH1 Q706 truncating mutation in the cells, which was also observed in the patient’s cfDNA with its enrichment increasing over time, supporting elevated disease burden. RNA-seq analysis comparing the primary tumor to metastases and the cell line reveal a signature for cell cycle progression and Akt signaling. To assess targetability, we subjected WCRC-25 to AZD5363 and Alpelisib which confirmed WCRC-25 as susceptible to PI3K/Akt signaling inhibition. Finally, we generated mouse xenograft models of WCRC-25 through mammary fat pad injection and observed small, but palpable tumors and metastasis to several sites. In conclusion, we report WCRC-25 as a novel ILC cell line with much promise as an invaluable research tool to advance our understanding of ILC and its therapeutic vulnerabilities.

Citation Format: Ashuvinee Elangovan, Emily A Bossart, Ahmed Basudan, Nilgun Tasdemir, Osama Shiraz Shah, Kai Ding, Carolin Meier, Tanya Heim, Lori Miller, Tiantong Liu, Shannon L Puhalla, Grzegorz Gurda, Peter C Lucas, Priscilla F McAuliffe, Jennifer M Atkinson, Adrian V Lee, Steffi Oesterreich. Wcrc-25: A novel luminal invasive lobular carcinoma cell line model [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-12-03.

Relevance of Platinum-free Interval and BRCA Reversion Mutations for Veliparib Monotherapy after Progression on Carboplatin/Paclitaxel for gBRCA Advanced Breast Cancer (BROCADE3 Crossover)

PURPOSE

Safety, efficacy, and exploratory biomarker analyses were evaluated in patients with advanced HER2-negative germline breast cancer susceptibility gene (gBRCA)-associated breast cancer enrolled in the BROCADE3 trial who received crossover veliparib monotherapy after disease progression on placebo plus carboplatin/paclitaxel.

PATIENTS AND METHODS

Eligible patients (N = 513) were randomized 2:1 to veliparib plus carboplatin/paclitaxel or placebo plus carboplatin/paclitaxel; patients had variable platinum-free intervals (PFI) at progression. In the placebo arm, patients were eligible to receive crossover veliparib monotherapy (300-400 mg twice daily continuous). Antitumor activity and adverse events were assessed during crossover veliparib treatment. BRCA reversion mutations at crossover were analyzed retrospectively using next-generation sequencing on plasma circulating tumor DNA (ctDNA).

RESULTS

Seventy-five patients in the placebo plus carboplatin/paclitaxel arm received ≥1 dose of crossover veliparib postprogression (mean treatment duration: 154 days). Eight of 50 (16%) patients with measurable disease had a RECIST v1.1 response. Activity was greater in patients with PFI ≥180 days compared with <180 days [responses in 23.1% (3/13) vs. 13.5% (5/37) of patients]. BRCA reversion mutations that restored protein function were detected in ctDNA from 4 of 28 patients tested, and the mean duration of crossover veliparib monotherapy was <1 month in these 4 patients versus 7.49 months in patients lacking reversion mutations. The most frequent adverse events were nausea (61%), vomiting (29%), and fatigue (24%).

CONCLUSIONS

Crossover veliparib monotherapy demonstrated limited antitumor activity in patients who experienced disease progression on placebo plus carboplatin/paclitaxel. PFI appeared to affect veliparib activity. BRCA reversion mutations may promote cross-resistance and limit veliparib activity following progression on platinum.

Prognostic factors and survival of patients undergoing surgical intervention for breast cancer bone metastases

INTRODUCTION

Bone is the most common distant site of breast cancer metastasis. Skeletal lesions can cause significant morbidity due to pain, pathologic fracture, and electrolyte abnormalities. Current treatment for patients with bone metastases (BoM) from breast cancer is highly personalized and often involves a multidisciplinary approach with chemotherapy, hormone therapy, bone-targeted antiresorptive agents, radiation therapy, and surgery. We have retrospectively collected clinical data from a series of patients with bone metastases to evaluate the clinical characteristics, prognostic factors, and survival patterns of patients with breast cancer BoM receiving standard multimodal therapy.

METHODS

A consecutive series of 167 patients with breast cancer BoM treated at a single institution between August 2013 and March 2020 were identified. Clinical information was obtained from the medical record and survival analyses were performed to evaluate patient outcomes and identify prognostic factors.

RESULTS

Thirty-seven patients (22%) presented with de novo BoM - bone metastases at the time of breast cancer diagnosis - and were 2.6 times more likely to die within the study period than those with asynchronous BoM (HR = 2.62, p = <0.0001). Patients who received bone-targeted medical therapy were 61% less likely to die after BoM diagnosis than those who did not (HR = 0.39, p = 0.001). Operative stabilization of BoM was more frequently employed in patients with lytic (p = 0.02) or mixed (p = 0.02) tumors than it was for those with blastic lesions. Patients treated with surgery had a lower overall bone metastasis survival than those treated without (p < 0.03).

DISCUSSION

These findings reflect the current patterns in metastatic breast cancer treatment and associated outcomes. In a series of 167 consecutive patients, we demonstrate the natural history of breast cancer with BoM being treated with modern multimodal therapy. Understanding these treatment patterns and prognostic factors enhances the provider's ability to counsel patients and direct appropriate treatments.

Efficacy and safety of first-line veliparib and carboplatin-paclitaxel in patients with HER2- advanced germline BRCA+ breast cancer: Subgroup analysis of a randomised clinical trial

BACKGROUND

Addition of veliparib to carboplatin-paclitaxel, with continuation of veliparib monotherapy if carboplatin-paclitaxel was discontinued, improved progression-free survival (PFS) in patients with germline BRCA-associated locally advanced/metastatic HER2- breast cancer and ≤2 lines of previous cytotoxic therapy for metastatic disease in BROCADE3. A pre-planned subgroup analysis evaluated efficacy and safety in patients without previous cytotoxic therapy for metastatic disease.

METHODS

Patients were randomised 2:1 to receive veliparib (120 mg orally BID) or placebo on days -2 to 5. Carboplatin (AUC 6) was administered on day 1, and paclitaxel (80 mg/m²) on days 1, 8 and 15 (21-day cycles). Patients discontinuing carboplatin-paclitaxel for reasons besides progression could continue veliparib/placebo monotherapy (300 mg BID, increasing to 400 mg BID if tolerated) until progression. The primary end-point was PFS assessed by investigator.

RESULTS

Of 509 patients in the intention-to-treat population (98.6% female; mean age 47, standard deviation 11), 413 (81%) had no previous cytotoxic therapy for metastatic disease (274, veliparib; 139, placebo). In the first-line subgroup, median PFS was 16.6 months (95% confidence interval [CI] 13.4-18.7) versus 13.1 months (95% CI 11.4-14.5) for the veliparib versus control groups (hazard ratio 0.70, 95% CI 0.54-0.89, P = .004). More patients were alive and progression-free at 2 years (36% versus 23.2%) and 3 years (27.9% versus 13.3%) in the veliparib versus control group. Adverse events unrelated to progression leading to study drug discontinuation occurred in 25 (9.1%) and 8 (5.8%) patients.

CONCLUSIONS

Veliparib with carboplatin-paclitaxel led to durable disease control among first-line patients, suggesting a benefit of this treatment approach in early lines.

CLINICAL TRIAL REGISTRATION

NCT02163694.

Veliparib (V) monotherapy after progression on placebo (PL) + carboplatin/paclitaxel (CP) in patients with advanced HER2-negative gBRCA-associated breast cancer: Crossover outcomes and exploratory biomarker analyses in BROCADE3

1097

Background: In BROCADE3 (NCT02163694), addition of the PARP inhibitor (PARPi) V to CP improved PFS in patients (pts) with g BRCA-associated advanced breast cancer (hazard ratio 0.71 [95% CI 0.57–0.88], p = 0.002). Reversion mutations may account for resistance to platinum-based CT and PARPi. Efficacy, safety, and exploratory biomarker analyses for pts randomized to PL + CP who received crossover (Cx) V monotherapy after progression are reported. Methods: 513 total pts were randomized 2:1 to V + CP or PL + CP. V/PL, C, and P could be discontinued independently prior to progression, leading to varying platinum-free intervals at the time of progression. After progression, pts in the PL + CP arm could receive open-label Cx V monotherapy (300–400 mg BID continuous), beginning within 60 d of progression and continuing to second progression. Adverse events (AEs) and activity during Cx V were assessed. Exploratory analysis of BRCA reversion mutations restoring BRCA1/2 protein function that emerged during PL + CP treatment was performed on plasma circulating tumor DNA using targeted-amplicon next generation sequencing. Results: At data cutoff, 75 pts initially randomized to PL + CP had ≥1 dose of Cx V. Mean (range) duration of Cx V was 154 d (2–966). Activity during Cx V is in the Table. Mean (range) platinum-free interval at time of first dose of Cx V was 3.1 mos (0.4–10.9) vs 8.1 mos (1.0–34.9) in pts who had progressed vs had not progressed by 24 wks after first dose of Cx V. BRCA reversion analysis was completed for 18 Cx pts. Reversion mutations were identified in 1/18 pts (5.6%). This patient had Cx V duration of 19 d and had progressed by 24 wks. BRCA reversion analysis on additional Cx pts will be presented. Most common AEs during Cx V were nausea (61%), vomiting (29%), fatigue (24%), and diarrhea (21%). Any grade anemia, neutropenia, and thrombocytopenia occurred in 7%, 15%, and 7% of pts. Three pts (4%) experienced a convulsion event. Conclusions: Platinum-free interval may influence efficacy of subsequent PARPi. Impact of BRCA reversion mutations warrants further evaluation. Cross-resistance may limit PARPi efficacy after platinum failure. Clinical trial information: NCT02163694 . [Table: see text]

Veliparib (V) monotherapy (monoTx) following combination therapy with V + carboplatin/paclitaxel (CP) in patients with gBRCA-associated advanced breast cancer: Exploratory results from BROCADE3

1091

Background: In BROCADE3 (NCT02163694), addition of PARP inhibitor V to CP resulted in improved progression-free survival (PFS) (HR 0.71 [95% CI 0.57−0.88], p=0.002) in patients (pts) with advanced HER2-negative breast cancer and g BRCA1/2 mutation. A subset of pts transitioned to V/placebo (PL) monoTx at an intensified dose/schedule after CP discontinuation prior to progression (investigator discretion). Here, we evaluate the impact of this transition on efficacy and safety. Methods: Pts were randomized 2:1 to CP with V (n=337) or PL (n=172). V (120 mg po BID) or PL was given on Days (D) −2 to 5, C (AUC 6) on D1, and P (80 mg/m2) on D1, 8, and 15 (21-day cycles). Pts who transitioned to monoTx received V/PL 300-400mg BID daily until progression. A Cox model with a time varying covariate indicating transition from V/PL with CP to V/PL monoTx was fit to estimate treatment effect during combination and monoTx phases. PFS by cycles of CP prior to monoTx and AEs during monoTx are summarized. Results: A subgroup of 136 (40%) and 58 (34%) pts on the V and PL arms, respectively, received monoTx. When a Cox model with a time-varying covariate was fit for PFS (per investigator), the nominal P-value for treatment by covariate interaction was 0.038. The HRs (95% CI) for V vs PL during combination therapy and monoTx were 0.81 (0.62–1.06) and 0.49 (0.33–0.73). The Table summarizes PFS by cycles of C and/or P prior to monoTx. Common AEs (>20% of pts) during V or PL monoTx were nausea (52%/10%), fatigue (23%/12%), headache (21%/17%), and diarrhea (21%/9%). Seizures (2.2%/0%) were reported during monoTx. Rates of cytopenias for V or PL monoTx were: anemia 12%/14%; neutropenia 13%/12%; and thrombocytopenia 10%/5%. Conclusions: These analyses suggest that pts treated with V + CP derive benefit from both combination therapy as well as V monoTx after CP discontinuation. Pts receiving V monoTx after ≤ 6 cycles of VCP experienced a similar benefit to those who transitioned to monoTx after 7–12 cycles of VCP, suggesting that V maintenance therapy may be suitable following a limited duration of combination therapy. Clinical trial information: NCT02163694 . [Table: see text]

Transcriptome Characterization of Matched Primary Breast and Brain Metastatic Tumors to Detect Novel Actionable Targets

BACKGROUND

Breast cancer brain metastases (BrMs) are defined by complex adaptations to both adjuvant treatment regimens and the brain microenvironment. Consequences of these alterations remain poorly understood, as does their potential for clinical targeting. We utilized genome-wide molecular profiling to identify therapeutic targets acquired in metastatic disease.

METHODS

Gene expression profiling of 21 patient-matched primary breast tumors and their associated brain metastases was performed by TrueSeq RNA-sequencing to determine clinically actionable BrM target genes. Identified targets were functionally validated using small molecule inhibitors in a cohort of resected BrM ex vivo explants (n = 4) and in a patient-derived xenograft (PDX) model of BrM. All statistical tests were two-sided.

RESULTS

Considerable shifts in breast cancer cell-specific gene expression profiles were observed (1314 genes upregulated in BrM; 1702 genes downregulated in BrM; DESeq; fold change > 1.5, Padj < .05). Subsequent bioinformatic analysis for readily druggable targets revealed recurrent gains in RET expression and human epidermal growth factor receptor 2 (HER2) signaling. Small molecule inhibition of RET and HER2 in ex vivo patient BrM models (n = 4) resulted in statistically significantly reduced proliferation (P < .001 in four of four models). Furthermore, RET and HER2 inhibition in a PDX model of BrM led to a statistically significant antitumor response vs control (n = 4, % tumor growth inhibition [mean difference; SD], anti-RET = 86.3% [1176; 258.3], P < .001; anti-HER2 = 91.2% [1114; 257.9], P < .01).

CONCLUSIONS

RNA-seq profiling of longitudinally collected specimens uncovered recurrent gene expression acquisitions in metastatic tumors, distinct from matched primary tumors. Critically, we identify aberrations in key oncogenic pathways and provide functional evidence for their suitability as therapeutic targets. Altogether, this study establishes recurrent, acquired vulnerabilities in BrM that warrant immediate clinical investigation and suggests paired specimen expression profiling as a compelling and underutilized strategy to identify targetable dependencies in advanced cancers.

Abstract PD4-01: First-line veliparib plus carboplatin/paclitaxel in patients with HER2-negative advanced/metastatic gBRCA-associated breast cancer: Planned subgroup analysis from the phase 3 BROCADE3 trial

Background: BROCADE3 (NCT02163694) evaluated the PARP inhibitor veliparib in combination with carboplatin/paclitaxel (C/P) vs placebo + C/P in patients with HER2-negative locally advanced/metastatic breast cancer and a germline BRCA1/2 mutation. In the intent-to-treat (ITT) population, investigator-assessed median progression-free survival (PFS) was 14.5 months for veliparib vs 12.6 months for placebo (hazard ratio=0.71 [95% CI 0.57-0.88], p=0.002); 75th percentile PFS was 39.9 months for veliparib vs 20.7 months for placebo. In this preplanned analysis, we evaluated efficacy and safety of veliparib plus C/P in patients with no previous cytotoxic chemotherapy for metastatic disease.

Methods: Patients with ≤2 prior lines of cytotoxic chemotherapy for metastatic breast cancer were randomized 2:1 to C/P with veliparib or C/P with placebo. Veliparib (120 mg p.o. BID) or placebo was given on Days −2 to 5, C (AUC 6 mg/mL/min IV) on Day 1, and P (80 mg/m2 IV) on Days 1, 8, and 15 (21-day cycles). Patients who discontinued both C and P for toxicity or reasons other than disease progression could continue veliparib/placebo monotherapy until progression. Monotherapy dose was 300 mg BID, increasing to 400 mg BID if tolerated. Although randomization was not stratified by lines of prior cytotoxic chemotherapy, the treatment arms were well-balanced with respect to this baseline characteristic. The primary endpoint was PFS as assessed by investigator. Secondary endpoints included overall survival (OS), clinical benefit rate (CBR), and objective response rate (ORR). Adverse events were monitored throughout the study. Analysis of PFS in patients with no prior cytotoxic therapy for metastatic disease was pre-planned.

Results: In the ITT population, 337 patients (81% of the entire cohort) received treatment as first line and were randomized to veliparib plus C/P and 172 patients to placebo plus C/P. Most patients received prior cytotoxic chemotherapy in the neo-adjuvant/adjuvant setting (66%, placebo plus C/P; 70%, veliparib plus C/P). Among the 81% of patients in each arm who had no prior cytotoxic chemotherapy in the metastatic setting, median PFS was longer in patients receiving veliparib plus C/P compared to placebo plus C/P (16.6 mo vs 13.1 mo), and median PFS for both arms was over 1 year (Table). Proportion of patients with a serious AE was 30.9% for placebo plus C/P and 33.1% for veliparib plus C/P; proportion with an AE leading to study drug discontinuation was 10.8% for placebo plus C/P and 15.6% for veliparib plus C/P. Additional safety data will be presented.

Conclusions: In patients with HER2-negative advanced/metastatic breast cancer and a germline BRCA1/2 mutation who had no prior cytotoxic chemotherapy for metastatic disease, veliparib with C/P demonstrated an improvement in median PFS over C/P alone. This benefit was durable with 25% of patients alive and progression free at nearly 4 years.

Table. Efficacy in patients with no prior cytotoxic chemotherapy for metastatic disease.Veliparib + C/P, n=274Placebo + C/P, n=139mPFS per INV (mo, 95% CI)16.6 (13.4, 18.7)13.1 (11.4, 14.5)PFS HR (95% CI)0.69 (0.54, 0.88)PFS 75th percentile (mo, 95% CI)46.3 (29.3, NR)22.6 (16.5, 27.2)mPFS per ICR (mo, 95% CI)21.5 (18.7, 29.2)14.0 (12.5, 16.5)PFS HR (95% CI)0.63 (0.47, 0.84)PFS 75th percentile (mo, 95% CI)NR33.3 (19.7, NR)mOS (mo, 95% CI) [interim]36.0 (32.0, 43.1)29.9 (26.0, 39.3)OS HR (95% CI)0.92 (0.68, 1.2)CBR at 24 weeks (% [95% CI])92.8 (90.0, 94.9)93.4 (89.1, 96.0)ORR (% [95% CI])79.7 (74.0, 84.7)76.3 (67.4, 83.8)

C/P, carboplatin and paclitaxel; CBR, clinical benefit rate; HR, hazard ratio; m, median; mo, months; NR, not reached; ORR, objective response rate; OS, overall survival; PFS, progression-free survival; INV, investigator; ICR, independent central review.

Citation Format: Banu K. Arun, Hyo S. Han, Bella Kaufman, Hans Wildiers, Michael Friedlander, Jean-Pierre Ayoub, Shannon L. Puhalla, Bruce A. Bach, Matthew Dudley, Christine K. Ratajczak, David Maag, Véronique Diéras. First-line veliparib plus carboplatin/paclitaxel in patients with HER2-negative advanced/metastatic gBRCA-associated breast cancer: Planned subgroup analysis from the phase 3 BROCADE3 trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD4-01.

Recurrent hyperactive ESR1 fusion proteins in endocrine therapy-resistant breast cancer

Background

Estrogen receptor-positive (ER-positive) metastatic breast cancer is often intractable due to endocrine therapy resistance. Although ESR1 promoter switching events have been associated with endocrine-therapy resistance, recurrent ESR1 fusion proteins have yet to be identified in advanced breast cancer.

Patients and methods

To identify genomic structural rearrangements (REs) including gene fusions in acquired resistance, we undertook a multimodal sequencing effort in three breast cancer patient cohorts: (i) mate-pair and/or RNAseq in 6 patient-matched primary-metastatic tumors and 51 metastases, (ii) high coverage (>500×) comprehensive genomic profiling of 287-395 cancer-related genes across 9542 solid tumors (5216 from metastatic disease), and (iii) ultra-high coverage (>5000×) genomic profiling of 62 cancer-related genes in 254 ctDNA samples. In addition to traditional gene fusion detection methods (i.e. discordant reads, split reads), ESR1 REs were detected from targeted sequencing data by applying a novel algorithm (copyshift) that identifies major copy number shifts at rearrangement hotspots.

Results

We identify 88 ESR1 REs across 83 unique patients with direct confirmation of 9 ESR1 fusion proteins (including 2 via immunoblot). ESR1 REs are highly enriched in ER-positive, metastatic disease and co-occur with known ESR1 missense alterations, suggestive of polyclonal resistance. Importantly, all fusions result from a breakpoint in or near ESR1 intron 6 and therefore lack an intact ligand binding domain (LBD). In vitro characterization of three fusions reveals ligand-independence and hyperactivity dependent upon the 3' partner gene. Our lower-bound estimate of ESR1 fusions is at least 1% of metastatic solid breast cancers, the prevalence in ctDNA is at least 10× enriched. We postulate this enrichment may represent secondary resistance to more aggressive endocrine therapies applied to patients with ESR1 LBD missense alterations.

Conclusions

Collectively, these data indicate that N-terminal ESR1 fusions involving exons 6-7 are a recurrent driver of endocrine therapy resistance and are impervious to ER-targeted therapies.

Pre- and Postoperative Neratinib for HER2-Positive Breast Cancer Brain Metastases: Translational Breast Cancer Research Consortium 022

PURPOSE

This pilot study was performed to test our ability to administer neratinib monotherapy before clinically recommended craniotomy in patients with HER2-positive metastatic breast cancer to the central nervous system, to examine neratinib's central nervous system penetration at craniotomy, and to examine postoperative neratinib maintenance.

PATIENTS AND METHODS

Patients with HER2-positive brain metastases undergoing clinically indicated cranial resection of a parenchymal tumor received neratinib 240 mg orally once a day for 7 to 21 days preoperatively, and resumed therapy postoperatively in 28-day cycles. Exploratory evaluations of time to disease progression, survival, and correlative tissue, cerebrospinal fluid (CSF), and blood-based analyses examining neratinib concentrations were planned. The study was registered at ClinicalTrials.gov under number NCT01494662.

RESULTS

We enrolled 5 patients between May 22, 2013, and October 18, 2016. As of March 1, 2019, patients had remained on the study protocol for 1 to 75+ postoperative cycles pf therapy. Two patients had grade 3 diarrhea. Evaluation of the CSF showed low concentrations of neratinib; nonetheless, 2 patients continued to receive therapy without disease progression for at least 13 cycles, with one on-study treatment lasting for nearly 6 years. Neratinib distribution in surgical tissue was variable for 1 patient, while specimens from 2 others did not produce conclusive results as a result of limited available samples.

CONCLUSION

Neratinib resulted in expected rates of diarrhea in this small cohort, with 2 of 5 patients receiving the study treatment for durable periods. Although logistically challenging, we were able to test a limited number of CSF- and parenchymal-based neratinib concentrations. Our findings from resected tumor tissue in one patient revealed heterogeneity in drug distribution and tumor histopathology.

Metaplastic breast carcinoma: a clinical-pathologic study of 97 cases with subset analysis of response to neoadjuvant chemotherapy

Metaplastic breast carcinoma is a rare heterogeneous category of breast cancer, often associated with a poor prognosis. Clinical-pathologic studies with respect to varied morphologic subtypes are lacking. There is also a dearth of studies assessing the response of metaplastic breast carcinoma to neoadjuvant chemotherapy. Cases of metaplastic breast carcinoma diagnosed between 2007 and 2017 were identified. Various clinical-pathologic variables were tested for association with survival. Patients who underwent neoadjuvant chemotherapy were assessed for pathologic response. Median age at diagnosis with metaplastic breast carcinoma was 64 years. With a median follow-up of 39 months, 26 patients (27%) recurred (24 distant and 2 loco-regional). The overall survival rate of the cohort was 66% (64/97). A number of variables were associated with survival in univariable analysis; however, in multivariable analysis, only lymph node status and tumor size (pT3 vs. pT1/2) were significantly associated with all survival endpoints: recurrence-free survival, distant recurrence-free survival, overall survival and breast cancer-specific survival. Twenty-nine of 97 (30%) patients with metaplastic breast carcinoma received neoadjuvant chemotherapy. Five (17%) patients achieved pathologic complete response. Matrix-producing morphology was associated with higher probability of achieving pathologic complete response (p = 0.027). Similar to other breast cancer subtypes, tumor size and lymph node status are prognostic in metaplastic carcinomas. The pathologic complete response rate of metaplastic breast carcinoma in our cohort was 17%, higher than previously reported. Although the matrix-producing subtype was associated with pathologic complete response, there was no survival difference with respect to tumor subtypes.

TBCRC 022: A Phase II Trial of Neratinib and Capecitabine for Patients With Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer and Brain Metastases

PURPOSE

Evidence-based treatments for metastatic, human epidermal growth factor receptor 2 (HER2)-positive breast cancer to the CNS are limited. We previously reported modest activity of neratinib monotherapy for HER2-positive breast cancer brain metastases. Here we report the results from additional study cohorts.

PATIENTS AND METHODS

Patients with measurable, progressive, HER2-positive brain metastases (92% after receiving CNS surgery and/or radiotherapy) received neratinib 240 mg orally once per day plus capecitabine 750 mg/m² twice per day for 14 days, then 7 days off. Lapatinib-naïve (cohort 3A) and lapatinib-treated (cohort 3B) patients were enrolled. If nine or more of 35 (cohort 3A) or three or more of 25 (cohort 3B) had CNS objective response rates (ORR), the drug combination would be deemed promising. The primary end point was composite CNS ORR in each cohort separately, requiring a reduction of 50% or more in the sum of target CNS lesion volumes without progression of nontarget lesions, new lesions, escalating steroids, progressive neurologic signs or symptoms, or non-CNS progression.

RESULTS

Forty-nine patients enrolled in cohorts 3A (n = 37) and 3B (n = 12; cohort closed for slow accrual). In cohort 3A, the composite CNS ORR = 49% (95% CI, 32% to 66%), and the CNS ORR in cohort 3B = 33% (95% CI, 10% to 65%). Median progression-free survival was 5.5 and 3.1 months in cohorts 3A and 3B, respectively; median survival was 13.3 and 15.1 months. Diarrhea was the most common grade 3 toxicity (29% in cohorts 3A and 3B).

Neratinib plus capecitabine is active against refractory, HER2-positive breast cancer brain metastases, adding additional evidence that the efficacy of HER2-directed therapy in the brain is enhanced by chemotherapy. For optimal tolerance, efforts to minimize diarrhea are warranted.

Abstract PD3-04: Analysis of ERBB2 (HER2) amplification by ctDNA in a phase Ib dose-escalation trial evaluating trastuzumab emtansine (T-DM1) with neratinib in women with metastatic disease with initially diagnosed HER2+ breast cancer: NSABP FB-10

Background:

In this phase Ib study, the activity of T-DM1 plus N was assessed in patients (pt) previously treated with trastuzumab, pertuzumab, and a taxane (H+P+T). Several mechanisms of resistance have been hypothesized in pts progressing following H+P+T, including acquired alterations in the ERBB (HER) family proteins, reactivation of bypass or parallel pathways, or selective elimination of HER2-overexpressing clones. Loss of HER2 amp has been shown to occur in 25-35% of pts with residual tumor after neoadjuvant therapy or in metastatic disease after initial therapy with chemotherapy and HER2-targeted agents. Data on concordance of HER2 status between tissue and blood is limited. In 7 pts with cfDNA HER2 amp, concomitant tissue was concordant in all 7 pairs and response to anti-HER2 therapy occurred in 6. In our study we have retrospectively analyzed cfDNA in blood samples obtained at study entry.

Methods:

Eligible pts had prior H+P+T as neoadjuvant therapy, or 1st-line metastatic disease, measurable disease, ECOG PS ≤2, and adequate hematologic, renal, and liver function. Pts with stable brain metastases were eligible. Treatment consisted of T-DM1 3.6 mg/kg iv q3wk and N 120, 160, 200, or 240 mg/d using a 3+3 dose-escalation design. HER2+ was determined at initial diagnosis; tissue confirmation at study entry (after H+P+T progression) was not required. Blood was collected in for pharmacokinetic analyses of N peak and trough, and for cfDNA using the Guardant360 assay, which is a 73-gene next-generation cfDNA-sequencing panel that detects SNVs, indels, CNAs, and fusions, utilizing Digital Sequencing and custom bioinformatics methods for error correction. The cut-off for HER2 amp was a copy number of ≥2.0 established by Guardant based on training-set data.

Results:

There were 27 H+P+T-resistant pts enrolled and all pts had a blood sample analyzed for HER2 amp. Eighteen pts were evaluable for efficacy at 6 wks and 11 pts at 12 wks. Dose-limiting toxicity occurred in 6 pts during cycle 1, 1 pt was withdrawn for non-compliance, and 2 pts were withdrawn for disease complications. The recommended phase II dose of N was determined to be 160 mg/d. Responses were seen at all dose-levels of N. Pharmacokinetic analyses did not show a clear relationship with either peak or trough and dose-level. Ten pts showed HER2 amp in blood and 17 were non-amp. Of 18 pts evaluable after 2 cycles (6 wks), 12 pts had an objective response (7 amp; 5 non-amp) and 5 had progressive disease (1 amp; 4 non-amp). At 12 wks, there were 3 CRs and 8 PRs (7 amp; 4 non-amp). All CRs were in amp pts and lasted 364, 510, and 859+ days.

Conclusions:

HER2 amp as determined by cfDNA was found in 10 of 27 pts. The deeper and more prolonged (&gt;12 wk) responses occurred in 7 of 10 amp HER2 pts v 4 of 17 non-amp HER2 pts (p=0.04). In our ongoing phase II study of this regimen concomitant tissue and blood will be analyzed to better understand potential benefit or lack of benefit, with continued use of anti-HER2 therapy after progression on anti-HER2 therapies.

Support: Puma Biotechnology, Inc.

Citation Format: Abraham J, Puhalla SL, Sikov WM, Montero AJ, Salkeni MA, Razaq WA, Beumer JH, Kiesel BF, Buyse ME, Adamson LM, Srinivasan A, Pogue-Geile KL, Allegra CJ, Nagy RJ, Jacobs SA. Analysis of ERBB2 (HER2) amplification by ctDNA in a phase Ib dose-escalation trial evaluating trastuzumab emtansine (T-DM1) with neratinib in women with metastatic disease with initially diagnosed HER2+ breast cancer: NSABP FB-10 [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 PD3-04.

Low Estrogen Receptor (ER)-Positive Breast Cancer and Neoadjuvant Systemic Chemotherapy: Is Response Similar to Typical ER-Positive or ER-Negative Disease?

OBJECTIVES

Pathologic complete response (pCR) rate after neoadjuvant chemotherapy was compared between 141 estrogen receptor (ER)-negative (43%), 41 low ER+ (13%), 47 moderate ER+ (14%), and 98 high ER+ (30%) tumors.

METHODS

Human epidermal growth factor receptor 2-positive cases, cases without semiquantitative ER score, and patients treated with neoadjuvant endocrine therapy alone were excluded.

RESULTS

The pCR rate of low ER+ tumors was similar to the pCR rate of ER- tumors (37% and 26% for low ER and ER- respectively, P = .1722) but significantly different from the pCR rate of moderately ER+ (11%, P = .0049) and high ER+ tumors (4%, P < .0001). Patients with pCR had an excellent prognosis regardless of the ER status. In patients with residual disease (no pCR), the recurrence and death rate were higher in ER- and low ER+ cases compared with moderate and high ER+ cases.

CONCLUSIONS

Low ER+ breast cancers are biologically similar to ER- tumors. Semiquantitative ER H-score is an important determinant of response to neoadjuvant chemotherapy.

Prognostic Significance of Modified Residual Disease in Breast and Nodes (mRDBN) Algorithm After Neoadjuvant Chemotherapy for Breast Cancer

OBJECTIVES

We hypothesized that prognostic accuracy of the residual disease in breast and lymph nodes (RDBN) method, which is calculated using residual tumor size, nodal involvement, and tumor grade, may be improved by incorporating residual tumor cellularity.

METHODS

Cases included 614 patients who underwent neoadjuvant therapy for breast cancer. Tumor size was adjusted for residual cellularity of invasive carcinoma and used to calculate modified RDBN (mRDBN) and compared with unmodified gross tumor size (gRDBN).

RESULTS

RDBN could be calculated in 428 cases. Relative risks of recurrence and death were significantly higher for RDBN-3 and RDBN-4 compared with RDBN-1. Kaplan-Meier analysis showed significant differences in disease-free survival and overall survival for estrogen receptor (ER)-negative/human epidermal growth factor receptor 2 (HER2)-negative and ER-positive/HER2-negative subgroups (P < .0001).

CONCLUSIONS

Both mRDBN and gRDBN provide prognostic information, particularly in HER2-negative carcinoma; however, mRDBN showed better stratification of RDBN-3 and RDBN-4 patients.

Abstract PD4-09: Combination FGFR4 and ER-targeted therapy for invasive lobular carcinoma

Background

Invasive Lobular Carcinoma (ILC) is an understudied subtype of breast cancer that requires novel therapies in the advanced setting. Distinctive properties of ILC include growth patterns, metastatic behavior, and receptor status (almost universally estrogen receptor (ER) positive). Our lab recently generated six long-term estrogen deprivation (LTED) models of ILC cells and performed RNA-Sequencing to identify differentially expressed genes compared to their parental cells cultured with estrogen. We overlapped these results with a previously published microarray dataset and found that FGFR4 is the most consistently overexpressed gene in the setting of acquired resistance to endocrine therapy in ILC cells.

Hypothesis

FGFR4 is an important mediator of resistance to endocrine therapy in ILC.

Methods

To study the role of FGFR4 in vitro, we used multiple shRNAs and specific small molecule inhibition for growth assays of ILC cells. To study the role of FGFR4 in de novo resistance to endocrine therapy, we collected 129 well curated ER+ ILC tumor specimens and performed gene expression analysis on the pre-treatment samples using a custom NanoString panel. To study the role of FGFR4 in acquired resistance, we collected over 50 pairs of primary-metastatic ER+ tumors and performed exon capture based RNA-Sequencing.

Results

FGFR4 inhibition decreases parental and LTED ILC cell growth in classic 2D conditions, in the setting of ultra-low attachment, and in colony formation assays. The LTED cells, with higher FGFR4 expression, are more sensitive to its inhibition. For the parental cells, combination FGFR4 and ER-targeting drugs results in synergistic decreases in growth. In our database of primary ILC clinical samples, increased expression of FGFR4 is predictive of shorter time to distant recurrence. For our collection of 50 paired, primary-metastatic ER+ tissues, FGFR4 expression increases on average &gt;2.5 fold in the metastatic setting, with large gains even in ductal carcinoma cases. Finally, in analyzing recently published cohorts of metastatic tumors, there is a significant enrichment of hotspot FGFR4 mutations in tumors originating in the breast, with &gt;2% of metastatic ILC tumors containing such a mutation.

Conclusion

FGFR4 may play an important role in both acquired and de novo resistance to endocrine therapy in ILC.

Citation Format: Levine KM, Chen J, Sikora MJ, Tasdemir N, Priedigkeit N, Tseng GC, Puhalla SL, Jankowitz RC, Dabbs DJ, McAuliffe PF, Lee AV, Oesterreich S. Combination FGFR4 and ER-targeted therapy for invasive lobular carcinoma [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 PD4-09.

Clinically Observed Estrogen Receptor Alpha Mutations within the Ligand-Binding Domain Confer Distinguishable Phenotypes

OBJECTIVE

Twenty to fifty percent of estrogen receptor-positive (ER+) metastatic breast cancers express mutations within the ER ligand-binding domain. While most studies focused on the constitutive ER signaling activity commonly engendered by these mutations selected during estrogen deprivation therapy, our study was aimed at investigating distinctive phenotypes conferred by different mutations within this class.

METHODS

We examined the two most prevalent mutations, D538G and Y537S, employing corroborative genome-edited and lentiviral-transduced ER+ T47D cell models. We used a luciferase-based reporter and endogenous phospho-ER immunoblot analysis to characterize the estrogen response of ER mutants and determined their resistance to known ER antagonists.

RESULTS

Consistent with their selection during estrogen deprivation therapy, these mutants conferred constitutive ER activity. While Y537S mutants showed no estrogen dependence, D538G mutants demonstrated an enhanced estrogen-dependent response. Both mutations conferred resistance to ER antagonists that was overcome at higher doses acting specifically through their ER target.

CONCLUSIONS

These observations provide a tenable hypothesis for how D538G ESR1-expressing clones can contribute to shorter progression-free survival observed in the exemestane arm of the BOLERO-2 study. Thus, in those patients with dominant D538G-expressing clones, longitudinal analysis for this mutation in circulating free DNA may prove beneficial for informing more optimal therapeutic regimens.

Abstract CT013: NSABP FB-10: Phase Ib dose-escalation trial evaluating trastuzumab emtansine (T-DMI) with neratinib (N) in women with metastatic HER2+ breast cancer (MBC)

Background:

T-DM1, an antibody-drug conjugate that delivers the maytansinoid antimicrotubule agent DM1 to antigen-expressing HER2+ cells thereby improving the therapeutic index, is FDA- approved as 2nd-line therapy in HER2+ MBC patients (pts) after prior trastuzumab (T) and a taxane. Most pts currently receive T and pertuzumab (P) as neoadjuvant for 1st-line therapy for MBC. A retrospective analysis of T-DM1 after T-P found a much lower tumor response rate (17%) than T-DM1 after T and taxane, as reported in EMILIA (43%). In NSABP FB-8, combining T, N, and paclitaxel achieved responses after T-DM1 progression, raising the possibility that N could reverse resistance to T-DM1.

Methods:

Eligible pts had prior T-P as neoadjuvant therapy for 1st-line metastatic treatment for HER2+ measurable disease, ECOG PS &lt;2, adequate hematologic, renal, and liver function. Treatment consisted of T-DM1 at 3.6 mg/kg iv q 3 wk and N at escalating doses of 120, 160, 200, and 240 mg/d continuously, using 3+3 design. Each cycle was 21 d. Clinical endpoints include determination of safety and efficacy. Primary diarrhea prophylaxis with intensive loperamide was required. To compare steady-state blood levels of N across dose levels samples were drawn at the start of cycle 2.

Results:

The RP2D is still undergoing evaluation. 17 T-P resistant pts were enrolled. Treatment-related grade 3 toxicities included diarrhea (2 pts), thrombocytopenia (3 pts), hypertension (2 pts), ALT elevation (1 pt), nausea (1 pt), and neutropenia (1 pt). Of 14 pts who were evaluable after 2 cycles of therapy, 3 had CRs and 6 had PRs (ORR 64%).

Dose (mg/day)No. of objective responses (CR/PR)/No. of evaluable (CR/PR/SD/PD)Duration of objective response (weeks)DLTs1205/5 (CR 2, PR 3)66+,51,26,15,91 (nausea and dehydration)1602/4 (CR 1, PR 1, PD 2)39+,6No2001/3 (PR 1, SD 1, PD 1)21No2401/2 (PR 1, SD 1)152 (diarrhea, nausea, vomiting)

Conclusions:

T-DM1 plus N was well tolerated at doses of 120, 160, and 200 mg/d. Anti-tumor activity did not appear to be dose-dependent. 5 evaluable pts treated at lowest dose of N (120 mg/d) responded. A randomized phase II study comparing N at 120 mg/d and 200 mg/d with T-DM1 is planned to better define efficacy and tolerance.

Support: Puma Biotechnology

Citation Format: Jame Abraham, Shannon L. Puhalla, Wiliam M. Sikov, Alberto J. Montero, Jan H. Beumer, Marc E. Buyse, Laura M. Adamson, Ashok Srinivasan, Katherine L. Pogue-Geile, Samuel A. Jacobs. NSABP FB-10: Phase Ib dose-escalation trial evaluating trastuzumab emtansine (T-DMI) with neratinib (N) in women with metastatic HER2+ breast cancer (MBC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT013. doi:10.1158/1538-7445.AM2017-CT013

Abstract 421: Comprehensive genomic analysis of metastatic breast cancers reveals ESR1 fusions as a recurrent mechanism of endocrine therapy resistance

Metastatic breast cancer is often intractable due to its inherent ability to overcome current therapies. Genomic alterations are frequently responsible for therapeutic resistance. To better understand genomic mechanisms of acquired resistance in breast cancer we undertook a detailed characterization of single nucleotide variation (SNV) and structural variation (SV) in paired primary-metastasis metachronous tumors from 6 breast cancer patients (median time to recurrence 7.3 years). In ER-positive recurrent tumors treated with endocrine therapies, we identified multiple metastatic-acquired variants in ESR1 including a novel constitutively active, ligand-independent ESR1-DAB2 gene fusion. Importantly, this fusion resulted from a breakpoint in intron 4, retaining the DNA-binding domain but eliminating the ligand-binding domain (LBD), concordant to a similar fusion reported previously in a xenograft model. Hybrid capture based genomic profiling from &gt;7,800 breast cancers identified similar exon/intron 4 fusions in 5 tumors with direct paired-read evidence. Using a novel copy number shift detection strategy, 58 additional tumors showed indirect evidence of a rearrangement at exon 4 based on a novel copy number shift detection strategy. ESR1 fusion and copy number shift positive tumors are strongly enriched in metastatic disease (78%; p&lt;10-4) supporting their expected involvement in endocrine therapy resistance. Clinical follow up was available for 7 patients. 6/7 tumors were clinically ER-positive and received extensive endocrine therapy with progressive disease. Together, these data indicate that ESR1 fusions involving exon/intron 4 are a recurrent, albeit rare, mechanism of endocrine therapy resistance in breast cancer. The absence of the LBD implies these fusions will not respond to other ERα targeted therapies. Additional studies are needed to identify appropriate treatment options to overcome this mechanism of resistance.

Citation Format: Ryan J. Hartmaier, Nolan Priedigkeit, Laurie Gay, Michael E. Goldberg, James Suh, Siraj Ali, Jeffery Ross, Michaela Tsai, Barbara Haley, Julio Peguero, Rena D. Callahan, Irina Sachelarie, John Cho, Amir Bahreini, Shannon L. Puhalla, Steffi Oesterreich, Aju Mathew, Peter C. Lucas, Nancy E. Davidson, Adam M. Brufsky, Philip J. Stephens, Juliann Chmielecki, Adrian V. Lee. Comprehensive genomic analysis of metastatic breast cancers reveals ESR1 fusions as a recurrent mechanism of endocrine therapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 421. doi:10.1158/1538-7445.AM2017-421

Mutation site and context dependent effects of ESR1 mutation in genome-edited breast cancer cell models

Background

Mutations in the estrogen receptor alpha (ERα) 1 gene (ESR1) are frequently detected in ER+ metastatic breast cancer, and there is increasing evidence that these mutations confer endocrine resistance in breast cancer patients with advanced disease. However, their functional role is not well-understood, at least in part due to a lack of ESR1 mutant models. Here, we describe the generation and characterization of genome-edited T47D and MCF7 breast cancer cell lines with the two most common ESR1 mutations, Y537S and D538G.

Methods

Genome editing was performed using CRISPR and adeno-associated virus (AAV) technologies to knock-in ESR1 mutations into T47D and MCF7 cell lines, respectively. Various techniques were utilized to assess the activity of mutant ER, including transactivation, growth and chromatin-immunoprecipitation (ChIP) assays. The level of endocrine resistance was tested in mutant cells using a number of selective estrogen receptor modulators (SERMs) and degraders (SERDs). RNA sequencing (RNA-seq) was employed to study gene targets of mutant ER.

Results

Cells with ESR1 mutations displayed ligand-independent ER activity, and were resistant to several SERMs and SERDs, with cell line and mutation-specific differences with respect to magnitude of effect. The SERD AZ9496 showed increased efficacy compared to other drugs tested. Wild-type and mutant cell co-cultures demonstrated a unique evolution of mutant cells under estrogen deprivation and tamoxifen treatment. Transcriptome analysis confirmed ligand-independent regulation of ERα target genes by mutant ERα, but also identified novel target genes, some of which are involved in metastasis-associated phenotypes. Despite significant overlap in the ligand-independent genes between Y537S and D538G, the number of mutant ERα-target genes shared between the two cell lines was limited, suggesting context-dependent activity of the mutant receptor. Some genes and phenotypes were unique to one mutation within a given cell line, suggesting a mutation-specific effect.

Conclusions

Taken together, ESR1 mutations in genome-edited breast cancer cell lines confer ligand-independent growth and endocrine resistance. These biologically relevant models can be used for further mechanistic and translational studies, including context-specific and mutation site-specific analysis of the ESR1 mutations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0851-4) contains supplementary material, which is available to authorized users.

Intrinsic Subtype Switching and Acquired ERBB2/HER2 Amplifications and Mutations in Breast Cancer Brain Metastases

IMPORTANCE

Patients with breast cancer (BrCa) brain metastases (BrM) have limited therapeutic options. A better understanding of molecular alterations acquired in BrM could identify clinically actionable metastatic dependencies.

OBJECTIVE

To determine whether there are intrinsic subtype differences between primary tumors and matched BrM and to uncover BrM-acquired alterations that are clinically actionable.

DESIGN, SETTING, AND PARTICIPANTS

In total, 20 cases of primary breast cancer tissue and resected BrM (10 estrogen receptor [ER]-negative and 10 ER-positive) from 2 academic institutions were included. Eligible cases in the discovery cohort harbored patient-matched primary breast cancer tissue and resected BrM. Given the rarity of patient-matched samples, no exclusion criteria were enacted. Two validation sequencing cohorts were used-a published data set of 17 patient-matched cases of BrM and a cohort of 7884 BrCa tumors enriched for metastatic samples.

MAIN OUTCOMES AND MEASURES

Brain metastases expression changes in 127 genes within BrCa signatures, PAM50 assignments, and ERBB2/HER2 DNA-level gains.

RESULTS

Overall, 17 of 20 BrM retained the PAM50 subtype of the primary BrCa. Despite this concordance, 17 of 20 BrM harbored expression changes (<2-fold or >2-fold) in clinically actionable genes including gains of FGFR4 (n = 6 [30%]), FLT1 (n = 4 [20%]), AURKA (n = 2 [10%]) and loss of ESR1 expression (n = 9 [45%]). The most recurrent expression gain was ERBB2/HER2, which showed a greater than 2-fold expression increase in 7 of 20 BrM (35%). Three of these 7 cases were ERBB2/HER2-negative out of 13 ERBB2/HER2-negative in the primary BrCa cohort and became immunohistochemical positive (3+) in the paired BrM with metastasis-specific amplification of the ERBB2/HER2 locus. In an independent data set, 2 of 9 (22.2%) ERBB2/HER2-negative BrCa switched to ERBB2/HER2-positive with 1 BrM acquiring ERBB2/HER2 amplification and the other showing metastatic enrichment of the activating V777L ERBB2/HER2 mutation. An expanded cohort revealed that ERBB2/HER2 amplification and/or mutation frequency was unchanged between local disease and metastases across all sites; however, a significant enrichment was appreciated for BrM (13% local vs 24% BrM; P < .001).

CONCLUSIONS AND RELEVANCE

Breast cancer BrM commonly acquire alterations in clinically actionable genes, with metastasis-acquired ERBB2/HER2 alterations in approximately 20% of ERBB2/HER2-negative cases. These observations have immediate clinical implications for patients with ERBB2/HER2-negative breast cancer and support comprehensive profiling of metastases to inform clinical care.

Abstract P6-09-14: Prognostic significance of a modified residual disease in breast and nodes (mRDBN) algorithm after neoadjuvant therapy for breast cancer

Background: Patients achieving pathologic complete response to neoadjuvant chemotherapy have excellent disease free and overall survival. For patients with residual disease, the residual disease in breast and lymph node (RDBN) method provides useful prognostic information. RDBN is calculated as follows: 0.2*tumor size (in cm)+lymph node status (0-3) + tumor grade (1-3). pCR, low, intermediate and high risk of recurrence categories correspond to RDBN index of 0, 0.1 to 2.9, 3 to &lt;4.4, and ≥ 4.4, respectively. We hypothesized that the prognostic accuracy of RDBN may be improved by also taking into account the residual tumor cellularity.

Methods: Retrospective review of 614 consecutive patients who underwent neoadjuvant therapy for breast cancer was performed. At our institution, tumor size/volume reduction in the breast is determined using the equation:

Estimated % tumor size reduction = [(pre-therapy clinical size – “revised” pathology tumor size)/pre-therapy clinical size]*100.

“Revised” pathology tumor size is calculated by multiplying the largest dimension of the gross tumor bed by the invasive tumor cellularity of the tumor bed (in comparison to the pre-therapy core biopsy sample). For example, if a 3 cm tumor bed has only 50% cellularity for invasive cancer (in comparison to pre-therapy core biopsy), the revised tumor size is 1.5 cm. Hence, we were able to use the “revised tumor size” for calculating the modified RDBN index (mRDBN). We also used gross tumor bed size for gross RDBN (gRDBN) to compare with mRDBN. mRDBN and gRDBN could be calculated on 459 of the 514 cases. Chi-Square statistical analysis was performed.

Results: Mean follow up was 33.1 months (median 31, range 4-70).

The results are shown in Table 1 & 2.

Table 1. Overall Recurrence and MortalityRDBN Score Category Overall Recurrence Mortality  nn (%)RR95% CI; pn (%)RR95% CI; pmRDBN (n=459)High5829 (50.0)19.63[7.22, 53.40]; p=&lt;0.000118 (31.0)16.24[4.97, 53.10]; p=&lt;0.0001Intermed16433 (20.1)7.9[2.86, 21.78]; p=&lt;0.000115 (9.1)4.79[1.41, 16.21]; p=0.006Low803 (3.8)1.47[0.34, 6.42]; p=0.694 (5.0)2.62[0.60, 11.41]; p=0.23pCR1574 (2.5)REF 3 (1.9)REF gRDBN (n=459)High8131 (38.3)15.02[5.49, 41.09]; p=&lt;0.000119 (23.5)12.28[3.74, 40.26]; p=&lt;0.0001Intermed14932 (21.5)8.43[3.05, 23.26]; p=&lt;0.000116 (10.7)5.62[1.67, 18.89]; p=0.003Low722 (2.8)1.09[0.20, 5.82]; p=12 (2.8)1.45[0.25, 8.51]; p=1pCR1574 (2.5)REF 3 (1.9)REF 

Table 2; Reclassification of gRDBN categoriesgRDBN mRDBN ReclassificationClassificationnLow (%)Intermed (%)High (%)Low7272 (100)0 (0)0 (0)Intermed1498 (5.4)140 (93.9)1 (0.7)High810 (0)24 (29.6)57 (70.4)

Conclusions: Both mRDBN and gRDBN provide prognostic information; however, separation of categories is improved with mRDBN (Table 1). mRDBN reclassified 30% of the high risk-gRDBN patients into intermediate risk category with a recurrence rate of 20%, leaving the 'true' high risk subgroup with a revised recurrence rate of 50% (Table 2). RDBN index also identified a group of low risk patients who have prognosis similar to patients with pCR.

Citation Format: Farrugia DJ, Landmann A, McAuliffe PF, Diego EJ, Johnson R, Bonaventura M, Soran A, Dabbs DJ, Clark B, Lembersky BC, Puhalla SL, Brufsky A, Jankowitz R, Davidson NE, Ahrendt GM, Bhargava R. Prognostic significance of a modified residual disease in breast and nodes (mRDBN) algorithm after neoadjuvant therapy for 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 P6-09-14.

Abstract P6-11-07: Methylation of BRCA1 and response to the PARP inhibitor veliparib

This abstract was not presented at the symposium.

Risedronate may preserve bone microarchitecture in breast cancer survivors on aromatase inhibitors: A randomized, controlled clinical trial

This study provides preliminary evidence that risedronate not only preserves BMD but may also attenuate the loss of bone microarchitecture over 2years during a time of accelerated bone loss in post-menopausal breast cancer survivors on aromatase inhibitors.

INTRODUCTION

Accelerated bone loss and elevated fracture risk are associated with the use of aromatase inhibitors (AIs) in women with breast cancer. We previously reported that the oral bisphosphonate, risedronate, can maintain bone mineral density (BMD) in the hip and spine over 2-years in post-menopausal breast cancer survivors on AIs. In this study, we examined whether oral bisphosphonates can also preserve bone microarchitecture as measured by the trabecular bone score (TBS) in this population.

METHODS

This 2-year randomized, double-blind, placebo-controlled trial included postmenopausal women over age 55 with breast cancer on an AI who had low bone mass. Participants provided informed consent and were randomized to risedronate 35mg once weekly or placebo. We examined 12- and 24-month changes in spine TBS, analyzed using linear mixed models.

RESULTS

One-hundred and nine women with a mean age of 70.5years were included in the analysis. In the placebo group, BMD declined at the spine and hip over the 24-month period but was preserved in the active treatment group (data previously reported). TBS declined in the placebo group by -2.1% and -2.3% at 12- and 24-months, respectively (p<0.005). The TBS percent change in bisphosphonate-treated patients was -0.9% and -1.3% at 12 and 24-months but did not reach statistical significance (p=0.24 and 0.14). The 12- and 24-month between-group differences were 0.9 (p=0.38) and 0.8 (p=0.44) percentage points. TBS change correlated with spine BMD changes in the placebo group at 12- and 24-months (r=0.33 and 0.34, p<0.01) but not in the active treatment group.

CONCLUSION

The oral bisphosphonate risedronate preserves BMD and may attenuate loss of bone microarchitecture over 2years during a time of accelerated bone loss in breast cancer survivors on AIs, but more definitive evidence is needed.

Polymorphisms in DNA repair and oxidative stress genes associated with pre-treatment cognitive function in breast cancer survivors: an exploratory study

PURPOSE

The purpose of this exploratory candidate gene association study was to examine relationships between polymorphisms in oxidative stress and DNA repair genes and pre-adjuvant therapy cognitive function (CF) in postmenopausal women diagnosed with early stage-breast cancer.

METHODS

Using a neuropsychological test battery, CF was assessed in 138 women diagnosed with breast cancer prior to initiation of adjuvant therapy and 81 age- and education-matched controls and summarized across eight composites. Participants were genotyped for 39 functional or tagging single nucleotide polymorphisms (SNPs) of select oxidative stress (CAT, GPX1, SEPP1, SOD1, and SOD2) and DNA repair (ERCC2, ERCC3, ERCC5, and PARP1) genes. Multiple linear regression was used to determine if the presence or absence of one or more minor alleles account for variability in CF composite scores. Based on regression findings from the analysis of individual SNPs, weighted multi-gene, multi-polymorphism genetic risk scores (GRSs) were calculated to evaluate the collective effect of possession of multiple protective and/or risk alleles.

RESULTS

Each CF composite was significantly (p < 0.05) associated with one or more oxidative stress and DNA repair gene polymorphisms evaluated either by SNP main effects and/or SNP-by-prescribed breast cancer treatment group interactions. Each computed GRS was found to be significantly (p < 0.001) related to its corresponding CF composite. All associations were positive suggesting that as overall genetic protection increases, CF composite score increases (indicating better performance).

CONCLUSIONS

These findings suggest that genetic variation in the oxidative stress and DNA repair pathways may play an important role in pre-adjuvant therapy CF in breast cancer survivors.

Translational Breast Cancer Research Consortium (TBCRC) 022: A Phase II Trial of Neratinib for Patients With Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer and Brain Metastases

PURPOSE

Evidence-based treatments for metastatic, human epidermal growth factor receptor 2 (HER2)-positive breast cancer in the CNS are limited. Neratinib is an irreversible inhibitor of erbB1, HER2, and erbB4, with promising activity in HER2-positive breast cancer; however, its activity in the CNS is unknown. We evaluated the efficacy of treatment with neratinib in patients with HER2-positive breast cancer brain metastases in a multicenter, phase II open-label trial.

PATIENTS AND METHODS

Eligible patients were those with HER2-positive brain metastases (≥ 1 cm in longest dimension) who experienced progression in the CNS after one or more line of CNS-directed therapy, such as whole-brain radiotherapy, stereotactic radiosurgery, and/or surgical resection. Patients received neratinib 240 mg orally once per day, and tumors were assessed every two cycles. The primary endpoint was composite CNS objective response rate (ORR), requiring all of the following: ≥ 50% reduction in volumetric sum of target CNS lesions and no progression of non-target lesions, new lesions, escalating corticosteroids, progressive neurologic signs/symptoms, or non-CNS progression--the threshold for success was five of 40 responders.

RESULTS

Forty patients were enrolled between February 2012 and June 2013; 78% of patients had previous whole-brain radiotherapy. Three women achieved a partial response (CNS objective response rate, 8%; 95% CI, 2% to 22%). The median number of cycles received was two (range, one to seven cycles), with a median progression-free survival of 1.9 months. Five women received six or more cycles. The most common grade ≥ 3 event was diarrhea (occurring in 21% of patients taking prespecified loperamide prophylaxis and 28% of those without prophylaxis). Patients in the study experienced a decreased quality of life over time.

CONCLUSION

Although neratinib had low activity and did not meet our threshold for success, 12.5% of patients received six or more cycles. Studies combining neratinib with chemotherapy in patients with CNS disease are ongoing.

Abstract B2-16: Identification of base pair mutations and structural rearrangements acquired in breast cancer metastases including a novel hyperactive ESR1-DAB2 fusion gene in hormone-resistant progression

DNA structural variations (SVs) are a major source of genetic instability in cancer, but they remain understudied. Large-insert mate-pair sequencing (MPS) is a powerful method designed to detect SVs, even in highly repetitive regions. Using MPS and other methods, we performed a comprehensive analysis of genomic alterations in breast cancer progression.

Matched primary/recurrent frozen tumor samples from 6 patients, including two patients from our rapid autopsy program with multiple metastatic tissues (20 total samples; average 5.5 years to recurrence) were examined by multiple large-insert library (3-5, 5-8, 8-12kb) MPS to identify metastatic acquired SVs. This was supplemented with RNAseq (n=15), whole exome sequencing (n=18;~75x), whole genome sequencing (n=3; 40-65x), and SNP arrays.

A relatively small fraction (~10%) of somatic single nucleotide variants (SNVs) in the primary tumor were identified in matched metastatic samples, and the majority of metastatic SNVs were not found in the matched primary tumor. This indicates that a rare sub-clone colonizes the metastatic site and evolves extensively before becoming clinically evident. For example, in one patient with an ER+ tumor who initially declined anti-estrogen therapy, the recently described ESR1 Y537S mutation was not present in the primary tumor or in metastatic disease 5 years later. However, after extensive anti-estrogen treatment for metastatic disease, the mutation was identified at rapid autopsy, indicating that this mutation can be acquired even after initial metastatic spread. Chromatin immunoprecipitation assays in metastatic tissue from tumors with mutant ERα show strong enrichment for ERα at classical ERα target genes and we are currently assessing the genome-wide binding pattern of ERα to identify novel binding sites.

We observed extensive patient-to-patient variability in the number and types of SVs. In general, the overall patterns of SVs were remarkably similar between matched primary and metastatic samples indicating that these events likely occurred early in tumorigenesis and are stable throughout disease progression. We identified a number of metastatic specific SVs that likely contribute to disease progression. Specifically, in one patient with an ER+ primary tumor treated with adjuvant Tamoxifen, we identified a novel fusion gene between ESR1 (estrogen receptor-α, ERα) and DAB2 (disabled-2) only in a lymph node recurrence. RT-PCR and western blot analysis confirmed that the fusion RNA/protein was expressed/translated only in the recurrent disease. The fusion retains the DNA-binding domain (DBD) and hinge region of ERα while the ligand-binding domain (LBD) is replaced with the majority of DAB2. We hypothesized that this is a functional genetic alteration conferring ligand-independent ERα-mediated signaling and growth. Confirming this, in vitro ERE-Tk-luc reporter assays showed that the ESR1-DAB2 fusion has ligand-independent activity that is 13-290x higher than wild-type ERα. We are currently assessing the genome-wide binding of ESR1-DAB2 and the functional contribution of DAB2 to the fusion protein.

This study represents the most comprehensive analysis to date of genomic changes in breast cancer progression and indicates extensive changes occur during metastatic spread. A number of acquired changes likely represent therapeutically targetable metastatic dependencies.

Citation Format: Ryan James Hartmaier, Amir Bahreini, Shannon L. Puhalla, Steffi Oesterreich, Aju Mathew, Nancy E. Davidson, Adam M. Brufsky, Adrian V. Lee. Identification of base pair mutations and structural rearrangements acquired in breast cancer metastases including a novel hyperactive ESR1-DAB2 fusion gene in hormone-resistant progression. [abstract]. In: Proceedings of the AACR Special Conference on Computational and Systems Biology of Cancer; Feb 8-11 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 2):Abstract nr B2-16.

Abstract A1-07: Identification of base pair mutations and structural rearrangements acquired in breast cancer metastases including a novel hyperactive ESR1-DAB2 fusion gene in hormone-resistant progression

DNA structural variations (SVs) are a major source of genetic instability in cancer, but they remain understudied. Large-insert mate-pair sequencing (MPS) is a powerful method designed to detect SVs, even in highly repetitive regions. Using MPS and other methods, we performed a comprehensive analysis of genomic alterations in breast cancer progression.

Matched primary/recurrent frozen tumor samples from 6 patients, including two patients from our rapid autopsy program with multiple metastatic tissues (20 total samples; average 5.5 years to recurrence) were examined by multiple large-insert library (3-5, 5-8, 8-12kb) MPS to identify metastatic acquired SVs. This was supplemented with RNAseq (n=15), whole exome sequencing (n=18;~75x), whole genome sequencing (n=3; 40-65x), and SNP arrays.

A relatively small fraction (~10%) of somatic single nucleotide variants (SNVs) in the primary tumor were identified in matched metastatic samples, and the majority of metastatic SNVs were not found in the matched primary tumor. This indicates that a rare sub-clone colonizes the metastatic site and evolves extensively before becoming clinically evident. For example, in one patient with an ER+ tumor who initially declined anti-estrogen therapy, the recently described ESR1 Y537S mutation was not present in the primary tumor or in metastatic disease 5 years later. However, after extensive anti-estrogen treatment for metastatic disease, the mutation was identified at rapid autopsy, indicating that this mutation can be acquired even after initial metastatic spread. Chromatin immunoprecipitation assays in metastatic tissue from tumors with mutant ERα show strong enrichment for ERα at classical ERα target genes and we are currently assessing the genome-wide binding pattern of ERα to identify novel binding sites.

We observed extensive patient-to-patient variability in the number and types of SVs. In general, the overall patterns of SVs were remarkably similar between matched primary and metastatic samples indicating that these events likely occurred early in tumorigenesis and are stable throughout disease progression. We identified a number of metastatic specific SVs that likely contribute to disease progression. Specifically, in one patient with an ER+ primary tumor treated with adjuvant Tamoxifen, we identified a novel fusion gene between ESR1 (estrogen receptor-α, ERα) and DAB2 (disabled-2) only in a lymph node recurrence. RT-PCR and western blot analysis confirmed that the fusion RNA/protein was expressed/translated only in the recurrent disease. The fusion retains the DNA-binding domain (DBD) and hinge region of ERα while the ligand-binding domain (LBD) is replaced with the majority of DAB2. We hypothesized that this is a functional genetic alteration conferring ligand-independent ERα-mediated signaling and growth. Confirming this, in vitro ERE-Tk-luc reporter assays showed that the ESR1-DAB2 fusion has ligand-independent activity that is 13-290x higher than wild-type ERα. We are currently assessing the genome-wide binding of ESR1-DAB2 and the functional contribution of DAB2 to the fusion protein.

This study represents the most comprehensive analysis to date of genomic changes in breast cancer progression and indicates extensive changes occur during metastatic spread. A number of acquired changes likely represent therapeutically targetable metastatic dependencies.

Citation Format: Ryan James Hartmaier, Amir Bahreini, Shannon L. Puhalla, Steffi Oesterreich, Aju Mathew, Nancy E. Davidson, Adam M. Brufsky, Adrian V. Lee. Identification of base pair mutations and structural rearrangements acquired in breast cancer metastases including a novel hyperactive ESR1-DAB2 fusion gene in hormone-resistant progression. [abstract]. In: Proceedings of the AACR Special Conference on Translation of the Cancer Genome; Feb 7-9, 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 1):Abstract nr A1-07.

Sensitive Detection of Mono- and Polyclonal ESR1 Mutations in Primary Tumors, Metastatic Lesions, and Cell-Free DNA of Breast Cancer Patients

PURPOSE

Given the clinical relevance of ESR1 mutations as potential drivers of resistance to endocrine therapy, this study used sensitive detection methods to determine the frequency of ESR1 mutations in primary and metastatic breast cancer, and in cell-free DNA (cfDNA).

EXPERIMENTAL DESIGN

Six ESR1 mutations (K303R, S463P, Y537C, Y537N, Y537S, D538G) were assessed by digital droplet PCR (ddPCR), with lower limits of detection of 0.05% to 0.16%, in primary tumors (n = 43), bone (n = 12) and brain metastases (n = 38), and cfDNA (n = 29). Correlations between ESR1 mutations in metastatic lesions and single (1 patient) or serial blood draws (4 patients) were assessed.

RESULTS

ESR1 mutations were detected for D538G (n = 13), Y537S (n = 3), and Y537C (n = 1), and not for K303R, S463P, or Y537N. Mutation rates were 7.0% (3/43 primary tumors), 9.1% (1/11 bone metastases), 12.5% (3/24 brain metastases), and 24.1% (7/29 cfDNA). Two patients showed polyclonal disease with more than one ESR1 mutation. Mutation allele frequencies were 0.07% to 0.2% in primary tumors, 1.4% in bone metastases, 34.3% to 44.9% in brain metastases, and 0.2% to 13.7% in cfDNA. In cases with both cfDNA and metastatic samples (n = 5), mutations were detected in both (n = 3) or in cfDNA only (n = 2). Treatment was associated with changes in ESR1 mutation detection and allele frequency.

CONCLUSIONS

ESR1 mutations were detected at very low allele frequencies in some primary breast cancers, and at high allele frequency in metastases, suggesting that in some tumors rare ESR1-mutant clones are enriched by endocrine therapy. Further studies should address whether sensitive detection of ESR1 mutations in primary breast cancer and in serial blood draws may be predictive for development of resistant disease. See related commentary by Gu and Fuqua, p. 1034.

The molecular landscape of premenopausal breast cancer

Introduction

Breast cancer in premenopausal women (preM) is frequently associated with worse prognosis compared to that in postmenopausal women (postM), and there is evidence that preM estrogen receptor-positive (ER+) tumors may respond poorly to endocrine therapy. There is, however, a paucity of studies characterizing molecular alterations in premenopausal tumors, a potential avenue for personalizing therapy for this group of women.

Methods

Using TCGA and METABRIC databases, we analyzed gene expression, copy number, methylation, somatic mutation, and reverse-phase protein array data in breast cancers from >2,500 preM and postM women.

Results

PreM tumors showed unique gene expression compared to postM tumors, however, this difference was limited to ER+ tumors. ER+ preM tumors showed unique DNA methylation, copy number and somatic mutations. Integrative pathway analysis revealed that preM tumors had elevated integrin/laminin and EGFR signaling, with enrichment for upstream TGFβ-regulation. Finally, preM tumors showed three different gene expression clusters with significantly different outcomes.

Conclusion

Together these data suggest that ER+ preM tumors have distinct molecular characteristics compared to ER+ postM tumors, particularly with respect to integrin/laminin and EGFR signaling, which may represent therapeutic targets in this subgroup of breast cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0618-8) contains supplementary material, which is available to authorized users.

Prevention of bone loss with risedronate in breast cancer survivors: a randomized, controlled clinical trial

In postmenopausal women with low bone mass and hormone-receptor-positive breast cancer on an aromatase inhibitor, risedronate maintained skeletal health assessed by bone density and turnover markers. Women with the greatest decreases in bone turnover markers at 12 months had the greatest increases in bone density at 24 months.

INTRODUCTION

Aromatase inhibitors (AIs), adjuvant endocrine therapy for postmenopausal women with hormone-receptor-positive breast cancer, are associated with bone loss and fractures. Our objectives were to determine if (1) oral bisphosphonate therapy can prevent bone loss in women on an AI and (2) early changes in bone turnover markers (BTM) can predict later changes in bone mineral density (BMD).

METHODS

We conducted a 2-year double-blind, placebo-controlled, randomized trial in 109 postmenopausal women with low bone mass on an AI (anastrozole, letrozole, or exemestane) for hormone-receptor-positive breast cancer. Participants were randomized to once weekly risedronate 35 mg or placebo, and all received calcium plus vitamin D. The main outcome measures included BMD, BTM [carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type 1 procollagen (P1NP)], and safety.

RESULTS

Eighty-seven percent completed 24 months. BMD increased more in the active treatment group compared to placebo with an adjusted difference at 24 months of 3.9 ± 0.7 percentage points at the spine and 3.2 ± 0.5 percentage points at the hip (both p < 0.05). The adjusted difference between the active treatment and placebo groups were 0.09 ± 0.04 nmol/LBCE for CTX and 23.3 ± 4.8 μg/mL for P1NP (both p < 0.05). Women with greater 12-month decreases in CTX and P1NP in the active treatment group had a greater 24-month increase in spinal BMD (p < 0.05). The oral therapy was safe and well tolerated.

CONCLUSION

In postmenopausal women with low bone mass and breast cancer on an AI, the oral bisphosphonate risedronate maintained skeletal health.

Abstract S1-03: Identification of base pair mutations and structural rearrangements acquired in breast cancer metastases including a novel hyperactive ESR1-DAB2 fusion gene specifically in hormone-resistant recurrence

DNA structural variations (SVs) are a major source of genetic instability in cancer, but they remain understudied. Large-insert mate-pair sequencing (MPS) is a powerful method designed to detect SVs, even in highly repetitive regions. Using MPS and other methods, we performed a comprehensive analysis of genomic alterations in breast cancer progression.

Matched primary/recurrent frozen tumor samples from 6 patients, including two patients from our rapid autopsy program with multiple metastatic tissues (20 total samples; average 5.5 years to recurrence) were examined by multiple large-insert library (3-5, 5-8, 8-12kb) MPS to identify metastatic acquired SVs. This was supplemented with RNAseq (n=15), whole exome sequencing (n=18; ∼75x), whole genome sequencing (n=3; 40-65x), and SNP arrays.

A relatively small fraction (∼10%) of somatic single nucleotide variants (SNVs) in the primary tumor were identified in matched metastatic samples, and the majority of metastatic SNVs were not found in the matched primary tumor. This indicates that a rare sub-clone colonizes the metastatic site and evolves extensively before becoming clinically evident. For example, in one patient with an ER+ tumor who initially declined anti-estrogen therapy, the recently described ESR1 Y537S mutation was not present in the primary tumor or in metastatic disease 5 years later. However, after extensive anti-estrogen treatment for metastatic disease, the mutation was identified at rapid autopsy, indicating that this mutation can be acquired even after initial metastatic spread.

We observed extensive patient-to-patient variability in the number and types of SVs. In general, the overall pattern of SVs was remarkably similar between matched primary and metastatic samples, however, we identified a number of metastatic specific SVs that likely contribute to disease progression. Specifically, in one patient with an ER+ primary tumor treated with adjuvant Tamoxifen, we identified a novel fusion gene between ESR1 (estrogen receptor-α, ERα) and DAB2 (disabled-2) only in a lymph node recurrence. RT-PCR and western blot analysis confirmed that the fusion RNA/protein was expressed/translated only in the recurrent disease. The fusion retains the DNA-binding domain (DBD) and hinge region of ERα while the ligand-binding domain (LBD) is replaced with the majority of DAB2. We hypothesized that this is a functional genetic alteration conferring ligand-independent ERα-mediated signaling and growth. Confirming this, in vitro ERE-Tk-luc reporter assays showed that the ESR1-DAB2 fusion has ligand-independent activity that is 13-290x higher than wild-type ERα. Chromatin immunoprecipitation assays in metastatic tissue from tumors with mutant ERα show strong enrichment for ERα at classical ERα target genes. We are currently assessing the genome-wide binding of ESR1-DAB2 and the functional contribution of DAB2 to the fusion protein.

This study represents the most comprehensive analysis to date of genomic changes in breast cancer progression and indicates extensive changes occur during metastatic spread. A number of acquired changes likely represent therapeutically targetable metastatic dependencies.

Citation Format: Ryan J Hartmaier, Shannon L Puhalla, Steffi Oesterreich, Amir Bahreini, Nancy E Davidson, Adam M Brufsky, Adrian V Lee. Identification of base pair mutations and structural rearrangements acquired in breast cancer metastases including a novel hyperactive ESR1-DAB2 fusion gene specifically in hormone-resistant recurrence [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr S1-03.

Abstract P4-05-03: Unique genetic, epigenetic, and transcriptomic changes in premenopausal breast cancer suggest novel strategies for therapy

Breast cancer in premenopausal women (preM) is frequently associated with worse prognosis compared to that in postmenopausal women (postM) even when controlling for prognostic variables. In particular, preM ER+ tumors have a poor prognosis on endocrine therapy. There is, however, a paucity of studies characterizing molecular alterations in premenopausal tumors, a potential avenue for finding personalized therapies for this group of women.

We analyzed gene expression, CNV, methylation, and somatic mutations in tumors from preM (≤45; ER+ n = 110, and ER- n = 39) and postM (≥55, ER+ n = 392, and ER- n = 102) women in The Cancer Genome Atlas (TCGA). Unbiased hierarchical clustering of 2,900 most variably expressed genes (using both RNA-seq and Agilent expression array data) in the whole dataset (n = 643) identified four major subtypes which correlated highly with the PAM50 defined subtypes LumA, LumB, Basal and HER2; however, there wasn't any separation between preM and postM samples. Similarly, principal component analysis using 10,000 genes with the highest inter-quartile range (IQR) demonstrated high similarity across preM and postM samples. Direct examination of gene expression differences between PreM and PostM ER+ tumors using unpaired t-test (5% FDR) identified 3,044 differentially expressed genes. The genes most upregulated in premenopausal tumors included AREG, TFPI2, MSMB, TCN1, and GLRA3. Ingenuity Pathway Analysis revealed a highly significant enrichment for TGFb (p&lt;1.9E-16) pathway activity in preM tumors. Intriguingly, no significant gene expression differences between preM and postM ER- tumors were identified. We thus then focused on genetic and epigenetic alterations that may underlie these transcriptomic changes in ER+ preM tumors.

Comparison of methylation (450K Illumina array) between preM and postM ER+ tumors showed a difference in 1% (n = 1,738) of the probes. Genes with the largest difference included ESR1, SIM2, and KLF6. Significant differences in DNA copy number variation (Affymetrix SNP 6.0 array) were also identified in ER+ preM tumors. A number of somatic mutations were significantly enriched in preM ER+ tumors including DSPP and GATA3. Integrated analysis also showed that approximately half of the observed differences in gene expression are driven by CNVs.

Conclusion: Our in silico study has identified a number of genes and pathways which are significantly altered between preM and postM ER+ breast cancer. Distinct genetic and epigenetic differences suggest unique etiology for some preM tumors. Currently ongoing Paradigm analysis, and confirmatory studies using METABRIC data are expected to further identify pathways that could specifically be targeted in premenopausal breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-05-03.

Prediction of the Oncotype DX recurrence score: use of pathology-generated equations derived by linear regression analysis

Oncotype DX is a commercial assay frequently used for making chemotherapy decisions in estrogen receptor (ER)-positive breast cancers. The result is reported as a recurrence score ranging from 0 to 100, divided into low-risk (<18), intermediate-risk (18-30), and high-risk (≥31) categories. Our pilot study showed that recurrence score can be predicted by an equation incorporating standard morphoimmunohistologic variables (referred to as original Magee equation). Using a data set of 817 cases, we formulated three additional equations (referred to as new Magee equations 1, 2, and 3) to predict the recurrence score category for an independent set of 255 cases. The concordance between the risk category of Oncotype DX and our equations was 54.3%, 55.8%, 59.4%, and 54.4% for original Magee equation, new Magee equations 1, 2, and 3, respectively. When the intermediate category was eliminated, the concordance increased to 96.9%, 100%, 98.6%, and 98.7% for original Magee equation, new Magee equations 1, 2, and 3, respectively. Even when the estimated recurrence score fell in the intermediate category with any of the equations, the actual recurrence score was either intermediate or low in more than 80% of the cases. Any of the four equations can be used to estimate the recurrence score depending on available data. If the estimated recurrence score is clearly high or low, the oncologists should not expect a dramatically different result from Oncotype DX, and the Oncotype DX test may not be needed. Conversely, an Oncotype DX result that is dramatically different from what is expected based on standard morphoimmunohistologic variables should be thoroughly investigated.

Abstract P6-07-02: Prediction of oncotype DX® recurrence score using pathology generated equations

BACKGROUND: Oncotype DX® is a quantitative reverse transcription polymerase chain reaction based assay that has been shown to have prognostic and predictive value in estrogen receptor (ER) positive breast cancers. The result is reported as a recurrence score (RS) ranging from 0–100, divided into low risk (&lt;18), intermediate risk (18–30), and high risk (≥31) categories. Prior studies have shown that RS is influenced by ER and progesterone receptor (PR) expression, HER2 status, proliferation index, and tumor grade. Our pilot study showed that RS can be predicted by an equation incorporating standard morpho-immunohistologic variables (referred to as Original Magee Equation; Mod Pathol. 2008;21:1255–1261).

METHODS: Using a dataset of 817 cases, we formulated three additional equations to predict the RS category for an independent set of 255 cases. Three models were built based on different hypotheses and data availability and are represented below.

New Magee Equation 1 (nME1): RS = 15.31385 + Nottingham score*1.4055+ ER H-score*(−0.01924) + PR H-score*(−0.02925) + (0 for HER2 negative, 0.77681 for equivocal, 11.58134 for HER2 positive) + Tumor size*0.78677 + KI67 index*0.13269.

New Magee Equation 2 (nME2): RS = 18.8042+ Nottingham score*2.34123 + ER H-score*(−0.03749) + PR H-score*(−0.03065) + (0 for HER2 negative, 1.82921 for equivocal, 11.51378 for HER2 positive) + Tumor size*0.04267.

New Magee Equation 3 (nME3): RS = 24.30812+ ER H-score*(−0.02177) + PR H-score*(−0.02884) + (0 for HER2 negative, 1.46495 for equivocal, 12.75525 for HER2 positive) + KI-67*0.18649.

RESULTS: The concordance between the risk category of oncotype DX® and our equations was 55.8%, 59.4%, and 54.4% for nME1, nME2, and nME3 respectively. With exclusion of the intermediate risk categories for both the actual RS and estimated RS, the concordance for each equation increased to more than 95%, reflecting the very low two step discordance (100% {76/76}, 98.6% {75/76}, and 98.7% {79/80} for nME1, nME2, and nME3 respectively). Even when the estimated RS fell in the intermediate category with any of the equations, the actual RS was either intermediate or low in more than 85% of the cases. The Pearson correlation coefficient between estimated and actual RS was similar for each of the equations (0.61661, 0.60386 and 0.59407 for nME1, nME2 and nME3, respectively).

CONCLUSIONS: Any of the 3 equations can be used to estimate the RS depending on available data. If the estimated RS is clearly high or low, the oncologists should not expect a dramatically different result from oncotype DX®, and the oncotype DX® test may not be needed. Conversely, an oncotype DX® result that is dramatically different from what is expected based on standard morpho-immunohistologic variables should be thoroughly investigated.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-07-02.

Abstract OT1-1-11: TBCRC 022: Phase II Trial of Neratinib for Patients with Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Breast cancer and Brain Metastases

Background: 1/3 of women with metastatic HER2+ breast cancer will develop central nervous system (CNS) metastases yet evidence-based treatments for women with progressive CNS disease are limited. Neratinib is an irreversible inhibitor of erbB1, HER2, and erbB4 which has promising activity in HER2+ breast cancer. Preclinical evidence suggests it may cross the blood brain barrier.

Trial Design: This is a multicenter, phase II, open-label study of neratinib for patients with HER2+ breast cancer and brain metastases. Neratinib is administered at 240 mg orally daily during a 28 day cycle. Two cohorts will be enrolled: Cohort 1 will enroll 40 patients with progressive CNS disease; cohort 2 will enroll ≤5 patients who are candidates for surgical excision of intracranial disease. Surgical candidates receive neratinib 7–21 days preoperatively and resume postoperatively. All patients are re-staged every 2 cycles. Those who develop non-CNS progression have an option to extend therapy with trastuzumab+neratinib. Circulating tumor cells (CTC) are collected at baseline and progression; neurocognitive testing, HADS and EORTC QLQ30/BN20 measures are administered at baseline, cycle 2, cycle 3, and progression (cohort 1). Intracranial tumor, cerebrospinal fluid (CSF), and plasma are collected at surgery (cohort 2).

Specific Aims: The primary endpoint is CNS objective response rate (ORR) by composite criteria. Additional endpoints include: non-CNS ORR, progression-free survival, overall survival (OS), site of 1st progression, and toxicity. Correlative and exploratory endpoints include association of CTC count and OS and longitudinal neurocognitive function and quality of life. In an exploratory analysis (cohort 2), we will quantify neratinib concentrations in CSF, intracranial tissue, and plasma and examine associations with response.

Eligibility: Patients must have confirmed HER2+ metastatic disease with ≥1 parenchymal brain lesion measuring ≥10 mm that is new or progressed after completing ≥1 line of standard CNS-directed treatment (cohort 1) or CNS disease that is amenable for surgery, including those without prior CNS treatments (cohort 2). Additional eligibility criteria (cohorts 1,2) include: adequate performance status and end organ/marrow function, and ejection fraction ≥50%. Any number of prior lines of therapy is allowed, including prior lapatinib.

Statistical Methods: Cohort 1 has a 2-stage design with up to 40 patients. CNS ORR is defined as ≥50% reduction in sum volume of CNS target lesions, without evidence of new lesions, progression of non-target CNS lesions, non-CNS disease progression, worsening neurological symptoms, or increase in corticosteroids. CNS lesion measurements are performed centrally by the Harvard Tumor Imaging Metrics Core. If 1/18 patients have a CNS response in the 1st stage, another 22 patients will enroll. With this design, if ≥5 of 40 patients achieve a CNS response, the drug will be deemed worthy of future study. This 2-stage design has 92% power to distinguish between a true CNS ORR of 20% and a null of 6% (one-sided type I error rate=9%).

Accrual: Accrual has begun. Target=45 (cohort 1=40, cohort 2=5)

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT1-1-11.

A phase I study of veliparib in combination with metronomic cyclophosphamide in adults with refractory solid tumors and lymphomas

PURPOSE

Oral administration of the alkylating agent cyclophosphamide at low doses, metronomic dosing, is well tolerated, with efficacy in multiple tumor types. PARP inhibition potentiates effects of cyclophosphamide in preclinical models. We conducted a phase I trial of the PARP inhibitor veliparib and metronomic cyclophosphamide in patients with refractory solid tumors and lymphoid malignancies.

EXPERIMENTAL DESIGN

Objectives were to establish the safety and maximum tolerated dose (MTD) of the combination; characterize veliparib pharmacokinetics (PK); measure poly(ADP-ribose) (PAR), a product of PARP, in tumor biopsies and peripheral blood mononuclear cells (PBMC); and measure the DNA-damage marker γH2AX in PBMCs and circulating tumor cells (CTC). Cyclophosphamide was administered once daily in 21-day cycles in combination with veliparib administered once daily for 7, 14, or 21 days.

RESULTS

Thirty-five patients were enrolled. The study treatment was well tolerated, and the MTD was established as veliparib 60 mg with cyclophosphamide 50 mg given once daily. Seven patients had partial responses; an additional six patients had disease stabilization for at least six cycles. PAR was significantly decreased in PBMCs (by at least 50%) and tumor biopsies (by at least 80%) across dose levels (DL); γH2AX levels were increased in CTCs from seven of nine patients evaluated after drug administration.

CONCLUSIONS

The combination of veliparib with metronomic cyclophosphamide is well tolerated and shows promising activity in a subset of patients with BRCA mutations. A phase II trial of the combination compared with single-agent cyclophosphamide is ongoing in BRCA-positive ovarian cancer, triple-negative breast cancer, and low-grade lymphoma.