Abstract 418P
Background
PD-1 inhibitors and EGFR inhibitors may provide potential synergy in R/M HNSCC. An open-label, multicenter phase Ib/II study (NCT04856631) was conducted to explore the safety and efficacy of toripalimab (anti-PD-1) combined with cetuximab in platinum-refractory (Cohort A) or untreated PD-L1 positive (Cohort B) R/M HNSCC patients. Here we report the updated results of Cohort B.
Methods
Patients with histologically confirmed R/M HNSCC, PD-L1 expression positive, and no prior exposure to systemic therapies for R/M disease or progressed at least 6 months after systemic therapy for local-regional disease were enrolled to receive toripalimab 240 mg intravenously (IV) Q3W and cetuximab (loading dose of 400 mg/m2 IV followed by 250 mg/m2 QW). The primary endpoint was investigator-assessed objective response rate (ORR) per RECIST v1.1. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety.
Results
By May 16, 2024, a total of 43 patients with 14.0 months median follow-up duration were enrolled in Cohort B. The median age was 60.0 years, and 39 (90.7%) patients were male. 21 (48.8%) patients had a primary tumor site in oral cavity, 23 (53.5%) had local recurrence only. The confirmed ORR was 41.9 (95% CI 27.0, 57.9) % with 2 CR, 16 PR and 16 SD observed. The median DOR was 15.8 (95% CI 9.4, NE) months. The median PFS was 8.2 (95% CI 4.2, 16.8) months and 1-year PFS rate was 44.0%. In the total population, PD-L1 CPS ≥ 20 (n = 18), and CPS 1-19 (n = 25) subgroups, the estimated median OS was 18.1 (95% CI 10.6, NE), NE (95% CI 9.3, NE), 15.8 (95% CI 8.7, NE) months, and 1-year OS rate was 62.2%, 72.2%, 54.2%, respectively. 40 (93.0%) patients experienced treatment-related adverse events, with 13 (30.2%) classified as Grade ≥ 3. AE led to treatment discontinuation in 1 (2.3%) patient. 1 (2.3%) treatment-related death was reported. No novel safety signal was observed beyond the known risk profiles of toripalimab and cetuximab.
Conclusions
Toripalimab combined with cetuximab showed promising clinical efficacy and manageable safety profile in previously untreated PD-L1 positive R/M HNSCC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Shanghai Junshi Biosciences.
Funding
Shanghai Junshi Biosciences.
Disclosure
All authors have declared no conflicts of interest.