Phase Ia/Ib study of the pan-class I PI3K inhibitor pictilisib (GDC-0941) administered as a single agent in Japanese patients with solid tumors and in combination in Japanese patients with non-squamous non-small cell lung cancer

Abstract

Pictilisib (GDC-0941) is an oral class I phosphatidylinositol-3-phosphate kinase inhibitor. This phase Ia/Ib study investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of pictilisib in monotherapy or in combination with carboplatin-paclitaxel and bevacizumab (CP + BEV) in Japanese patients with advanced solid tumors or non-squamous non-small cell lung cancer. A standard 3 + 3 dose escalation design was applied. In stage 1, 140, 260, or 340 mg/day of pictilisib was administered once daily to 12 patients with advanced solid tumors. In stage 2, 260 or 340 mg/day of pictilisib was administered in combination with CP + BEV to 7 patients with advanced non-squamous non-small cell lung cancer. In stage 1, 1 of 6 patients in the 340 mg/day cohort exhibited dose limiting toxicity (DLT) of grade 3 maculopapular rash. The maximum plasma concentration and area under the curve of pictilisib were dose-dependent. A reduction in phosphorylated AKT in platelet rich plasma was observed. No patient had an objective anti-tumor response. In stage 2, DLT was observed in 1 of 3 patients in the 260 mg/day cohort (grade 3 febrile neutropenia), and 2 of 4 patients in the 340 mg/day cohort (1 each of grade 3 febrile neutropenia and grade 3 febrile neutropenia/erythema multiforme). Partial responses were observed in 3 out of 7 patients. In conclusion, pictilisib was shown to have good safety and tolerability in Japanese patients with advanced solid tumors. A recommended dose of pictilisib in monotherapy was determined to be 340 mg once daily. For combination with CP + BEV, tolerability up to 260 mg/day was confirmed.

Keywords: Non-sq NSCLC; PI3K inhibitor; Phase Ia/Ib trial; Pictilisib; Solid tumor.