Temozolomide plus cisplatin versus toripalimab (anti-PD-1) as adjuvant therapy in resected mucosal melanoma.

Abstract

9508 Background: Chemotherapy (temozolomide plus cisplatin) has been demonstrated to be a better adjuvant regimen compared to high-dose interferon alpha-2b in resected Mucosal Melanoma (MuM) in the pre-immunotherapy era. Yet in the present immunotherapy era, PD-1 inhibitor was recommended as a standard adjuvant therapy for resected Melanoma. No adjuvant trial comparing chemotherapy with PD-1 inhibitor in resected MuM had been reported. we conducted this study to determine the efficacies of adjuvant chemotherapy versus PD-1 inhibitor in resected MuM. Methods: All patients (pts) with resected MuM received chemotherapy (temozolomide 200 mg/m2/day orally on days 1 to 5 plus cisplatin 75 mg/m2 i.v. on days 1-3, repeated every 3 weeks for six cycles) or Toripalimab (anti-PD-1, 3 mg/kg every 2 weeks via intravenous infusion) as adjuvant therapy from 2013 to 2019 were included retrospectively. Demographic and clinical characteristics between the two groups were matched with 1:1 by propensity score matching (PSM) to reduce the bias. After PSM, the efficacies of the two groups were compared, and subgroup analysis was performed according to the baseline characteristics. The endpoints were relapse-free survival (RFS), distant metastasis-free survival (DMFS), and overall survival (OS). Kaplan-Meier methods and Cox regressions were used to estimate median RFS, DMFS, OS and HR. Results: A total of 247 pts were included, of which 78 were in the Toripalimab group and 169 were in the Chemo group. PSM matched 65 pts from each of the two groups. The baseline characteristics were similar. At a median follow-up of 52.6 months (95%CI, 44.6-60.6 months), patients receiving chemo had a longer median RFS (28.2 vs. 12.0 months; HR=0.64, 95% CI, 0.42 to 0.98; P=0.04), DMFS (42.0 vs. 19.0 months; HR=0.58, 95% CI, 0.36 to 0.92; P=0.02) and OS (93.4 vs. 39.3 months; HR=0.56, 95% CI, 0.33 to 0.94; P=0.03) versus the toripalimab group (Table). Conclusions: Adjuvant chemotherapy (temozolomide plus cisplatin) shows remarkable longer RFS, DMFS, and OS than Toripalimab (anti-PD-1). It suggested that adjuvant chemotherapy may be a better option for patients with resected mucosal melanoma even in the present immunotherapy era. [Table: see text]