Safety, pharmacokinetics, and antitumor activity findings from a phase 1b, open-label, dose-escalation and expansion study investigating RAF dimer inhibitor lifirafenib in combination with MEK inhibitor mirdametinib in patients with advanced or refractory solid tumors

Abstract

Abstract Background: RAF dimer inhibition can suppress RAF-dependent MEK reactivation leading to sustained MAPK pathway inhibition. RAF dimer inhibitor lifirafenib (L) synergized with MEK inhibitor mirdametinib (M) in RAS-mutated cancer models. In this ongoing Phase 1b study of L+M in patients (pts) with advanced/refractory solid tumors harboring MAPK pathway aberrations, we investigate preliminary safety, PK, and efficacy. Methods: Pts were enrolled by a 3+3 design and treated with L (15-20 mg QD) + M (2-4 mg QD or BID) across 9 dose levels (DLs). Primary objectives were to evaluate safety/tolerability, estimate MTD, and identify recommended Phase 2 dose (RP2D)..