A Phase Ib Study of Sotrastaurin, a PKC Inhibitor, and Alpelisib, a PI3Kα Inhibitor, in Patients with Metastatic Uveal Melanoma

by Selleckchem | May 13 2023

Uveal melanoma (UM) is a rare subset of melanoma characterized by the presence of early initiating GNAQ/11 mutations, with downstream activation of the PKC, MAPK, and PI3Kα pathways. Activity has been observed with the PKC inhibitors sotrastaurin (AEB071) and darovasertib (IDE196) in patients with UM. Inhibition of the PI3K pathway enhances PKC inhibition in in vivo models. We therefore conducted a phase Ib study of sotrastaurin in combination with the PI3Kα inhibitor alpelisib to identify a tolerable regimen that may enhance the activity of PKC inhibition alone. Patients with metastatic uveal melanoma (n = 24) or GNAQ/11 mutant cutaneous melanoma (n = 1) were enrolled on escalating dose levels of sotrastaurin (100-400 mg BID) and alpelisib (200-350 mg QD). The primary objective was to identify the maximum tolerated dose (MTD) of these agents when administered in combination. Treatment-related adverse events (AE) occurred in 86% (any grade) and 29% (Grade 3). No Grade 4-5-related AEs occurred. Dose Level 4 (sotrastaurin 200 mg BID and alpelisib 350 mg QD) was identified as the maximum tolerated dose. Pharmacokinetic analysis demonstrated increasing concentration levels with increasing doses of sotrastaurin and alpelisib, without evidence of interaction between agents. Pharmacodynamic assessment of pMARCKS and pAKT protein expression with drug exposure suggested modest target inhibition that did not correlate with clinical response. No objective responses were observed, and median progression-free survival was 8 weeks (range, 3-51 weeks). Although a tolerable dose of sotrastaurin and alpelisib was identified with pharmacodynamic evidence of target inhibition and without evidence of a corresponding immunosuppressive effect, limited clinical activity was observed.

Comments：

This is a summary of a phase Ib study that investigated the combination of sotrastaurin, a PKC inhibitor, and alpelisib, a PI3Kα inhibitor, in patients with metastatic uveal melanoma or GNAQ/11 mutant cutaneous melanoma. The primary objective was to identify the maximum tolerated dose (MTD) of these agents when administered in combination. The study enrolled 24 patients with metastatic uveal melanoma and 1 patient with GNAQ/11 mutant cutaneous melanoma.

The study found that the combination of sotrastaurin and alpelisib was tolerable, with treatment-related adverse events occurring in 86% of patients (any grade) and 29% of patients (Grade 3). No Grade 4-5-related adverse events occurred. The maximum tolerated dose was identified as sotrastaurin 200 mg BID and alpelisib 350 mg QD. Pharmacokinetic analysis demonstrated increasing concentration levels with increasing doses of sotrastaurin and alpelisib, without evidence of interaction between agents. Pharmacodynamic assessment of pMARCKS and pAKT protein expression with drug exposure suggested modest target inhibition that did not correlate with clinical response.

However, no objective responses were observed, and the median progression-free survival was 8 weeks (range, 3-51 weeks). The study concluded that although the combination of sotrastaurin and alpelisib was tolerable, with evidence of target inhibition, limited clinical activity was observed in this cohort of patients with metastatic uveal melanoma or GNAQ/11 mutant cutaneous melanoma.