A phase 1/1b, open-label, dose-escalation study of PD-1 inhibitor, cetrelimab alone and in combination with FGFR inhibitor, erdafitinib in Japanese patients with advanced solid tumors

Immune checkpoint inhibitors are the leading approaches in tumor immunotherapy. The aim of the study was to establish recommended phase 2 doses (RP2Ds) of intravenous cetrelimab, a checkpoint inhibitor, alone and with oral erdafitinib in Japanese patients with advanced solid tumors. This open-label, non-randomized, dose-escalation phase 1/1b study enrolled adults with advanced solid tumors who were ineligible for standard therapy. Study was conducted in two parts: phase 1a assessed cetrelimab at three dosing levels (80 mg every 2 weeks [Q2W], 240 mg Q2W, and 480 mg Q4W); phase 1b assessed cetrelimab+erdafitinib at two dosing levels (240 mg Q2W + 6 mg once daily [QD] and 240 mg Q2W + 8 mg QD). Primary endpoint was frequency and severity of dose-limiting toxicities (DLTs) of cetrelimab ± erdafitinib. In total 22 patients (phase 1a, n = 9; phase 1b, n = 13) were enrolled. Median duration of follow-up was 8.64 months in phase 1a and 2.33 months in phase 1b. In phase 1a, DLTs weren’t reported while in phase 1b, 1 patient who received 240 mg cetrelimab + 6 mg erdafitinib reported Stevens-Johnson syndrome (grade 3, immune-related). Overall, 88.9% patients in phase 1a (grade ≥ 3: 44.4%) and 100.0% in phase 1b (grade ≥ 3: 53.8%) experienced ≥ 1 treatment-related adverse events (TEAEs); 33.3% in phase 1a and 38.5% in phase 1b reported serious TEAEs, of which 11.1% patients in phase 1a and 15.4% in phase 1b had TEAEs which led to treatment discontinuation. Cetrelimab alone and in combination with erdafitinib showed manageable safety in Japanese patients with advanced solid tumors. RP2Ds were determined as 480 mg cetrelimab Q4W for monotherapy, and cetrelimab 240 mg Q2W + erdafitinib 8 mg QD for combination therapy.