A Phase Ib Study of Alpelisib (BYL719), a PI3Kalpha
Mené sur 26 patientes atteintes d'un cancer du sein
Purpose: Alpelisib, a selective oral inhibitor of the class I PI3K catalytic subunit p110
α, has shown synergistic antitumor activity with endocrine therapy against ER+/PIK3CA-mutated breast cancer cells. This phase Ib study evaluated alpelisib plus letrozole's safety, tolerability, and preliminary activity in patients with metastatic ER+ breast cancer refractory to endocrine therapy. Patients and Methods: Twenty-six patients received letrozole and alpelisib daily. Outcomes were assessed by standard solid-tumor phase I methods. Tumor blocks were collected for DNA extraction and next-generation sequencing. Results: Alpelisib's maximum-tolerated dose (MTD) in combination with letrozole was 300 mg/d. Common drug-related adverse events included hyperglycemia, nausea, fatigue, diarrhea, and rash with dose-limiting toxicity occurring at 350 mg/d of alpelisib. The clinical benefit rate (lack of progression
≥6 months) was 35% (44% in patients with PIK3CA-mutated and 20% in PIK3CA wild-type tumors; 95% CI, 17%–56%), including five objective responses. Of eight patients remaining on treatment ≥12 months, six had tumors with a PIK3CA mutation. Among evaluable tumors, those with FGFR1/2 amplification and KRAS and TP53 mutations did not derive clinical benefit. Overexpression of FGFR1 in ER+/PIK3CA mutant breast cancer cells attenuated the response to alpelisib in vitro. Conclusion: The combination of letrozole and alpelisib was safe, with reversible toxicities. Clinical activity was observed independently of PIK3CA mutation status, although clinical benefit was seen in a higher proportion of patients with PIK3CA-mutated tumors. Phase II and III trials of alpelisib and endocrine therapy in patients with ER+ breast cancer are ongoing. Clin Cancer Res; 1–9. ©2016 AACR.
http://clincancerres.aacrjournals.org/content/early/2016/11/18/1078-0432.CCR-16-0134