Eganelisib, a First-in-Class PI3K-γ Inhibitor, in Patients with Advanced Solid Tumors: Results of the Phase 1/1b MARIO-1 Trial.

PURPOSE: Eganelisib (IPI-549) is a first-in-class, orally administered, highly selective phosphoinositide-3-kinase (PI3K)-γ inhibitor with anti-tumor activity alone and in combination with programmed cell death protein 1/ligand 1 (PD-1/PD-L1) inhibitors in preclinical studies. This phase 1/1b first-in-human, MAcrophage Reprogramming in Immuno-Oncology-1 (MARIO-1; NCT02637531) study evaluated the safety and tolerability of once-daily eganelisib as monotherapy and in combination with nivolumab in patients with solid tumors.

PATIENTS AND METHODS: Dose-escalation cohorts received eganelisib 10-60 mg as monotherapy (n=39) and 20-40 mg when combined with nivolumab (n=180). Primary endpoints included incidence of dose-limiting toxicities (DLTs) and adverse events (AEs).

RESULTS: The most common treatment-related grade ≥3 toxicities with monotherapy were increased alanine aminotransferase (ALT; 18%), aspartate aminotransferase (AST; 18%), and alkaline phosphatase (5%). No DLTs occurred in the first 28 days; however, toxicities meeting DLT criteria (mostly grade 3 reversible hepatic enzyme elevations) occurred with eganelisib 60 mg in later treatment cycles. In combination, the most common treatment-related grade ≥3 toxicities were increased AST (13%) and increased ALT and rash (10%). Treatment-related serious adverse events occurred in 5% of monotherapy patients (grade 4 bilirubin and hepatic enzyme increases in one patient each) and 13% in combination (pyrexia, rash, cytokine release syndrome, and infusion-related reaction in ≥2 patients each). Anti-tumor activity was observed in combination, including patients who had progressed on PD-1/PD-L1 inhibitors.

CONCLUSIONS: Based on the observed safety profile, eganelisib doses of 30 mg and 40 mg once daily in combination with PD-1/PD-L1 inhibitors were chosen for phase 2 study.