Adjuvant PD-1 antibody in recurrent, previously irradiated oral cavity cancer treated with salvage surgery

Objectives: The role of re-irradiation after salvage surgery for recurrent oral cavity cancer (OCC) is controversial. We evaluated the efficacy and safety of adjuvant toripalimab (PD-1 antibody) in this patient setting.Materials and methods: In this phase II study, patients after salvage surgery with OCC occurring in an area of previously irradiated were enrolled. Patients received toripalimab 240 mg once every 3 weeks for 12 months, or combined with S-1 orally for 4-6 cycles. The primary endpoint was 1-year progression-free survival (PFS).Results: Between April 2019 and May 2021, 20 patients were enrolled. Sixty percent patients had ENE or positive margins, 80% were restaged as stage IV, and 80% were previously treated with chemotherapy. The 1-year PFS and overall survival (OS) were 58.2%, and 93.8%, respectively, for patients with CPS & GE; 1, which was signifi-cantly better than those of the real-world reference cohort (p = 0.001 and 0.019). No grade 4-5 toxicities were reported, and only one patient experienced grade 3 immune related adrenal insufficiency and discontinued treatment. The 1-year PFS and OS were significantly different for patients with CPS < 1, CPS 1-19 and CPS & GE; 20 (p = 0.011 and 0.017, respectively). The peripheral blood B cell proportion was also correlated with PD in 6 months (p = 0.044).Conclusion: Adjuvant toripalimab or combine with S-1 after salvage surgery showed improved PFS compared with a real-world reference cohort in recurrent, previously irradiated OCC, and favorable PFS were observed in patients with a higher CPS and peripheral B cell proportion. Further randomized trials are warranted.