0000000000542401
AUTHOR
Jerry Y. Hsu
A phase II study of the PI3K inhibitor taselisib (GDC-0032) combined with fulvestrant (F) in patients (pts) with HER2-negative (HER2-), hormone receptor-positive (HR+) advanced breast cancer (BC).
520Background: The PI3K pathway is activated in HR+ BC, often via gain-of-function mutations in PIK3CA that occur in ~40% of HR+ BC. Taselisib is a potent and selective PI3K inhibitor, with greater selectivity against mutant PI3Kα isoforms than wild type (WT) PI3Kα. Phase Ib data demonstrated good tolerability and preliminary efficacy for taselisib + F in HR+ BC. Methods: This Phase II, open-label, single-arm study enrolled post-menopausal pts with HER2-, HR+ locally advanced or metastatic BC (mBC) who had progression or non-response to ≥ 1 prior endocrine therapy in adjuvant or mBC settings. Pts received taselisib (6 mg capsule PO qd) plus F (500 mg IM on Cycle 1 Day 1, Cycle 1 Day 15, the…
Phase II Study of Taselisib (GDC-0032) in Combination with Fulvestrant in Patients with HER2-Negative, Hormone Receptor–Positive Advanced Breast Cancer
AbstractPurpose: This single-arm, open-label phase II study evaluated the safety and efficacy of taselisib (GDC-0032) plus fulvestrant in postmenopausal women with locally advanced or metastatic HER2-negative, hormone receptor (HR)-positive breast cancer.Patients and Methods: Patients received 6-mg oral taselisib capsules daily plus intramuscular fulvestrant (500 mg) until disease progression or unacceptable toxicity. Tumor tissue (if available) was centrally evaluated for PIK3CA mutations. Adverse events (AE) were recorded using NCI-CTCAE v4.0. Tumor response was investigator-determined using RECIST v1.1.Results: Median treatment duration was 4.6 (range: 0.9–40.5) months. All patients expe…
Abstract PD5-2: Ph1b study of the PI3K inhibitor taselisib (GDC-0032) in combination with letrozole in patients with hormone receptor-positive advanced breast cancer
Abstract Background: Taselisib (GDC-0032) is a next-generation PI3K inhibitor with increased anti-tumor activity against PIK3CA mutant (MT) cancers. Taselisib is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that taselisib has enhanced activity against PI3K alpha isoform (PIK3CA) MT breast cancer cell lines and enhanced antitumor activity when combined with letrozole. Clinical data with single-agent taselisib also showed increased tumor shrinkage in patients with PIK3CA MT breast cancer as compared to patients with PIK3CA…