Treatment patterns and clinical outcomes among patients (pts) with HER2+ advanced breast cancer (ABC) and germline BRCA1/2 mutation(s) (gBRCA1/2mut): Results from a US real-world study.

Authors

null

Elias Obeid

Fox Chase Cancer Center, Philadelphia, PA

Elias Obeid , Rohan Parikh , Elizabeth Esterberg , Bhakti Arondekar , Abigail Hitchens , Lillian Shahied Arruda , Alexander Niyazov

Organizations

Fox Chase Cancer Center, Philadelphia, PA, RTI Health Solutions, Research Triangle Park, NC, Pfizer Inc., Collegeville, PA, RTI International, Research Triangle Park, NC, Pfizer Inc., New York, NY

Research Funding

Pharmaceutical/Biotech Company
Pfizer

Background: gBRCA1/2mut ABC represents ~5% of all breast cancer (BC) including pts with HER2+ BC. While HER2-targeted therapy remains an effective tx for those pts, limited information is available on the use and effectiveness of PARP inhibitors (PARPi) for pts with HER2+ gBRCA1/2mut ABC. Recently, NCCN updated its guidelines (v1.2020) to support the use of PARPi in pts with gBRCA1/2mut metastatic BC regardless of subtype. In order to establish a baseline reference point, we assessed real-world tx patterns and clinical outcomes among pts with gBRCA1/2mut HER2+. Methods: Oncologists retrospectively reviewed charts (July-Oct 2019) of randomly selected pts ≥18 y, with gBRCA1/2mut HER2+ABC who received ≥1 cytotoxic chemotherapy (CT) regimen(s) for ABC between Jan 2013-April 2018. Descriptive analysis was performed for 1st line ABC tx patterns. Clinical outcomes (1st line ABC PFS rates) were estimated using the Kaplan-Meier method. PARPi clinical outcomes data was immature given its recent launch. Additional analyses evaluating outcomes in pts receiving PARPi are planned. Results: Of the 225 pts with gBRCA1/2mut ABC included in the study, 48 (21%) female pts had HER2+ disease. Of the gBRCA1/2mut HER2+ pts, 77% were white with a median age of 58 y. Clinical characteristics: 42% HR+/HER2+, 56% HR-/HER2+, 2% had unknown HR/HER2+ ABC. Txs in the 1st line setting for HR+/HER2+ ABC pts (n = 20) included: CT (75%), CT + HER2-targeted therapy (25%) (Table). First-line txs used for HR-/HER2+ ABC pts (n = 27) included: CT + HER2-targeted therapy (78%), CT (15%), other (7%) (Table). 12-month PFS for 1st line HR+/HER2+ pts was 73% and for HR-/HER2+ pts was 69% (Table). Later line tx patterns will be presented. Conclusions: In this analysis of pts with gBRCA1/2mut HR+/HER2+, unexpectedly low rates of HER2-targeted therapy were observed. As expected, high rates of HER2-targeted therapy with CT were observed among gBRCA1/2mut HR-/HER2+ pts. Clinical outcome findings demonstrate the need for more efficacious tx options. Studies assessing clinical outcomes among gBRCA1/2mut HER2+ ABC pts receiving PARPi +/- HER2-targeted tx are warranted. This is a limited sample size; additional data collection including median PFS is ongoing.

Common 1st line tx patterns and 12-month PFS rates by HR status among gBRCA1/2 HER2+ ABC pts.

HR+/HER2+HR-/HER2+
N2027
Tx patternsCT (75%), CT + HER2-targeted therapy (25%)CT + HER2-targeted therapy (78%), CT (15%), other (7%)
N2026
12-month PFS rates73%69%

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Abstract Details

Meeting

2020 ASCO Virtual Scientific Program

Session Type

Publication Only

Session Title

Publication Only: Breast Cancer—Metastatic

Track

Breast Cancer

Sub Track

Other Breast Cancer Subtypes

Citation

J Clin Oncol 38: 2020 (suppl; abstr e13076)

DOI

10.1200/JCO.2020.38.15_suppl.e13076

Abstract #

e13076

Abstract Disclosures