A retrospective study of anti-PD-1 combined with temozolomide adjuvant therapy for stage III resected acral melanoma

Purpose This retrospective study was conducted to determine whether the combination of adjuvant anti-PD-1 therapy and temozolomide (TMZ) could improve the disease-free survival (DFS) of patients with resected stage III acral melanoma (AM). Method We retrospectively identified patients with resected stage III AM who had undergone adjuvant treatment with either anti-PD-1 therapy or the combination of anti-PD-1 and TMZ during the period from September 2018 to September 2023. Propensity score matching (PSM) was employed to compare the two cohorts (PD-1 vs combination therapy) with respect to DFS. The patients' clinical data were retrospectively analyzed to determine the variables influencing prognosis. Result In this study, 123 out of 184 patients were incorporated following propensity score matching (PSM). In the combined group, the 1-year DFS rate attained 65.85% (95% confidence interval [CI]: 52.83–82.09), whereas the 1-year DFS rate in the PD-1 group was merely 43.90% (p = 0.0028; 95% CI: 34.37–56.07). Hazard factor analysis further corroborated that the combination therapy was associated with a more favorable prognosis. In the subgroup analysis, the findings indicated that in patients with more advanced tumors (tumor stage IIIC and IIID), the combination therapy yielded a better outcome compared to PD-1 monotherapy. Moreover, patients with NRAS mutations might derive greater benefits from the combined treatment (P-interaction = 0.037). Conclusion The combination of anti-PD-1 and TMZ exhibited a marked improvement in the prognosis of resected stage IIIC and IIID AM patients in contrast to anti-PD-1 monotherapy.