Eganelisib, a First-in-Class PI3Kγ Inhibitor, in Patients with Advanced Solid Tumors: Results of the Phase 1/1b MARIO-1 Trial

Clin Cancer Res. 2023 Jun 13;29(12):2210-2219. doi: 10.1158/1078-0432.CCR-22-3313.


Purpose: Eganelisib (IPI-549) is a first-in-class, orally administered, highly selective PI3Kγ inhibitor with antitumor 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 (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 (DLT) and adverse events (AE).

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 AEs 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). Antitumor activity was observed in combination, including patients who had progressed on PD-1/PD-L1 inhibitors.

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

Publication types

  • Clinical Trial, Phase I
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Angiogenesis Inhibitors / therapeutic use
  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Humans
  • Immune Checkpoint Inhibitors / therapeutic use
  • Neoplasms* / drug therapy
  • Nivolumab* / therapeutic use
  • Programmed Cell Death 1 Receptor


  • Nivolumab
  • Antibodies, Monoclonal, Humanized
  • Programmed Cell Death 1 Receptor
  • Immune Checkpoint Inhibitors
  • Angiogenesis Inhibitors