Abstract PD8-01: Race and age differences in PAM50 biomarker status in the Carolina breast cancer study

Background: African American breast cancer patients have lower relative frequency of hormone receptor (HR)-positive/HER2-negative disease and higher subtype-specific mortality. However, few population-based studies have RNA-based subtyping data, and racial differences in the biology of HR-positive/HER2-negative tumors are not well understood.

Methods: Using data and biospecimens from the Carolina Breast Cancer Study (CBCS) Phase 3 (2008-2013), we classified approximately 1,000 invasive breast cancers according to PAM50 subtype and two risk of recurrence scores (ROR-P and ROR-PT). Relative frequency of Luminal A, Luminal B, Her2-enriched, and Basal-like subtypes and ROR scores (low/medium/high) were compared by race (blacks vs. whites) and age (≤50 years vs. >50 years), overall and among HR-positive/HER2-negative cases.

Results: Black women of all ages had significantly higher relative frequency of Basal-like breast cancer (36 and 31% in blacks vs. 18 and 15% in whites; younger and older, respectively) and lower frequency of Luminal A breast cancer (26 and 34% in blacks vs. 43 and 52% in whites; younger and older, respectively). Frequency of Luminal B and HER2-enriched breast cancer did not vary by race or age. Among clinically HR-positive, HER2-negative cases, Luminal A subtype comprised only half of the cases among black women, and was significantly less common than among white women (51% vs 60% in whites, p<0.05). Black women with HR-positive/HER2-negative disease also had significantly higher ROR scores (ROR-P medium or high 82% vs. 66% in whites, p=0.01; ROR-PT medium or high 85% vs. 69% in whites, p<0.01).

Conclusions: Multi-gene assays highlight disparities in frequency of aggressive, poorer prognosis tumor subtypes and implicate differences in tumor biology as an important contributor to mortality disparities among HR-positive/HER2-negative patients.

Citation Format: Troester MA, Sun X, Allott EH, Kit C-K, Thorne L, Mathews M, Cohen SM, Geradts J, Kirk E, Li Y, Hu Z, Robinson W, Hoadley KA, Reeder-Hayes K, Earp S, Olshan AF, Carey LA, Perou CM. Race and age differences in PAM50 biomarker status in the Carolina breast cancer study [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 PD8-01.

Abstract PD6-07: Genomic sequencing in metastatic breast cancer patients to inform clinical practice at the University of North Carolina at Chapel Hill

Background: An increasing number of molecularly-targeted therapies for metastatic breast cancer (MBC) are clinically-available (approved and investigational). These anti-cancer agents target specific molecular abnormalities such as mutated, amplified, deleted, or rearranged genes. Reporting of unique tumor genetic alterations is not included in routine clinical/diagnostic panels. In MBC, knowledge of mutational status may foster efficient transitions in clinical care and trial enrollment at disease progression. We describe the development and implementation of a clinically-integrated genomic sequencing program and report how information regarding targetable genomic aberrations in MBC patients (pts) is used to improve clinical practice in an academic setting.

Methods: Genomic sequencing of investigative biomarkers was prospectively offered to pts with MBC. DNA libraries were prepared separately from a retrieved archival FFPE tumor sample and a matched normal sample from each pt. Relevant targets were enriched by custom Agilent SureSelect hybrid capture baits using standard protocols. Samples were sequenced on Illumina HiSeq 2000/2500 platforms. Mutational findings were reviewed by a molecular tumor board (MTB); variants identified to be potentially actionable underwent confirmatory testing in a CLIA-approved laboratory. Confirmed findings were inserted into the pt's EMR accessible by both the pt and the treating oncologist.

Results: Of the 725 MBC pts seen at UNC since 1/1/2012, 194 (27%) contributed samples for genomic sequencing. Of those whose tumors were sequenced, average age at MBC diagnosis was 54 (25 - 91); 73% were Caucasian, 16% African American. De novo MBC accounted for 39 (20%) sequenced pts. Of sequenced patients, sites of metastatic disease included bone only (7%), visceral only (46%), and both bone and visceral (47%). Approximately 1/3 of pts were consented for sequencing at time of initial MBC diagnosis, 1/4 after 1st line therapy for MBC, and the remaining at or beyond their 2nd line. In total, 131 (68%) pts have sequencing results available of which 43% of pts had reportable mutations deemed actionable by the MTB. Specific mutations and observed frequency by subtype are shown below. Pts (19%) whose tumors were sequenced were more commonly enrolled in a therapeutic clinical trial for MBC, a higher rate than seen in the non-sequenced group (7%) (p<0.001). To date, 27% of pts' tumors harbored an alteration that is an eligibility requirement for a molecularly-targeted therapeutic trial accruing pts at UNC.

Observed Mutation by Clinical Subype Genes Total # (56 pts)HR+/HER2- (25 pts)HER2+ (13 pts)TNBC (18pts)PIK3CA15933TP5315456CCND19531NF-14103FGFR13300PTEN3012KRAS2011MDM22110PIK3R12002ROS12011TSC12011Other*14518TOTAL73281728*Mutations observed only once

Conclusion: Preemptive genomic sequencing can be integrated into the clinical and operational practice of a comprehensive cancer center. Currently this research tool and program provides valuable information that has the potential to foster both clinical trial eligibility and/or enrollment. With longer follow-up, we hope such an approach ultimately will improve patient outcomes.

Citation Format: Grilley-Olsen J, Keith KC, Hayward M, Dees EC, Deal A, Ivanova A, Benbow JM, Parker J, Patel NM, Eberhard D, Mieczkowski P, Weck KE, Hayes DN, Muss H, Jolly T, Reeder-Hayes K, Earp HS, Sharpless N, Carey L, Anders CK. Genomic sequencing in metastatic breast cancer patients to inform clinical practice at the University of North Carolina at Chapel Hill. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD6-07.

Abstract P2-16-13: Phase I dose escalation clinical trial of the PI3K inhibitor BKM120 and capecitabine (C) in metastatic breast cancer (MBC)

Background: PIK3CA is one of the most frequently mutated genes in human breast cancer, and the high expression of a PIK3CA-pathway signature is associated with the poor prognosis Luminal B and Basal-like expression subtypes. BKM120 is an oral pan-class I phosphatidylinositol-3-kinase (PI3K) inhibitor, which has shown activity in preclinical and early clinical testing, and synergy with both endocrine and chemotherapy. In this trial we sought to evaluate the safety and estimate the maximum tolerated dose (MTD) of the combination of BKM120 and C in patients (pts) with MBC.

Methods: In a 3+3 dose escalation design, we evaluated four cohorts of BKM 120 daily plus C BID x 14 days in 21 day cycles. Standard definitions for DLT and MTD were used and evaluated on the first cycle. Toxicity was graded by CTCAE version 4. Response was evaluated after 2 cycles by RECIST criteria. Pts with MBC appropriate for treatment with C who had <4 prior chemotherapy regimens and normal organ, bone marrow and cardiac parameters were eligible.

Results: 21 pts (11 hormone receptor (HR)+, 3 HER2+, 9 HR/HER2-negative) were enrolled and treated. All were evaluable for toxicity and 14 for response to date. Median age was 54 (range 35-65). Median prior chemotherapy regimens for MBC was 2 (range 1-4). The following dose levels (DL) were evaluated: BKM120 50 mg/d + C 1000 mg/m2/BID x 14(DL 1-4 pts), BKM120 80 mg/d + C 1000 mg/m2/BID x 14 (DL2-3 pts), BKM120 100 mg/d + C 1000 mg/m2/BID x 14 (DL3-9 pts), BKM120 100 mg/d + C 1250 mg/m2/BID x 14 (DL4-5 pts). Most frequent adverse events (all grades) included: Nausea (12), mood disorders (11), PPE (9), diarrhea (8), fatigue (7), vomiting (5) mucositis (4), rash (4), photosensitivity (3), hyperglycemia (3). Grade 3 or higher AEs in any cycle were transaminitis (3) diarrhea (2) mood disorder (2), hyperglycemia, fatigue, photosensitivity, PPE (1 pt each). DLTs: grade 3 hyperglycemia (1/6 pts at DL3), and grade 3 mood disorder in 1/5 pts DL 4. Additionally 4 of 5 patients at DL 4 required dose reduction or delay prior to C3D1. Thus DL 4 exceeded the MTD and DL 3 was expanded for further safety evaluation. Antitumor activity was seen with best responses of 1 CR (at DL 3), 3 PR (DL1 and 4) and 7 SD.

PK analysis, assessment of tumor PIK3CA mutation status and intrinsic subtype by PAM50 is ongoing.

Conclusions: The combination of BKM120 100 mg po q day and C 1000 mg/m2 / BID x 14 d in 21 day cycles is tolerable and appears active. PK and biomarker analysis are ongoing. A phase II trial is planned.

Acknowledgements: This study was funded by Novartis Pharmaceuticals and by a grant from Susan G. Komen for the Cure (SAC 110044).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-13.

Who gets genomic testing for breast cancer recurrence risk?

BACKGROUND/AIMS

Our study examined whether patient characteristics, beliefs and decision-making styles were associated with uptake of genomic testing for breast cancer recurrence risk.

METHODS

Participants were 132 early-stage breast cancer patients eligible for the Oncotype DX genomic test. We interviewed patients in 2009-2010 and obtained information from medical charts.

RESULTS

Half of the women eligible for genomic testing for breast cancer recurrence risk received it. The most common reason for not getting the test was that women's physicians did not offer it (80%). Test recipients were more likely to be unsure about receiving chemotherapy treatment compared to women who did not receive the test (p < 0.05). Women who received the test had less advanced disease pathologies, recalled a lower objective recurrence risk, perceived lower recurrence risk, and were slightly younger (all p < 0.05). Most women who described their decision-making style as active received the test (75%), whereas few women who described their style as passive received the test (12%) (p < 0.01).

CONCLUSION

In the university clinic we studied, genomic testing appeared to be more common among patients who may benefit most from the information provided by results, but confirmation in larger studies is needed.