Outcome of neoadjuvant immunotherapy for patients with resectable stage III/IV cutaneous melanoma: A Swedish nationwide population-based study (NEO-MEL).

Abstract

9565 Background: Randomized trials have shown that neoadjuvant immune checkpoint inhibitor (ICI) improves outcomes compared with adjuvant therapy alone in patients with resectable stage III–IV cutaneous melanoma. Furthermore, pathological response was a strong predictor for relapse-free survival (RFS). The translationability to routine real-world patients is unknown. Methods: This population-based cohort study included all patients with macroscopic, resectable cutaneous melanoma treated with neoadjuvant immune checkpoint inhibitor(s) across all academic melanoma centers in Sweden between January 1, 2022 and December 30, 2025. Clinical and pathological data were extracted from medical records. Results: A total of 279 patients initiated neoadjuvant ICI and received a median of two treatment cycles, 94% received PD1-inhibitor monotherapy, 91% underwent surgery as planned and 251 had evaluable pathological assessment. Among all patients who started treatment, 37% had a complete pathological response (pCR), 6% near pCR, 15% a partial pathological response (pPR) and 32% no pathological response (pNR). At a median follow-up time of 20 months, the estimated 24-month event-free survival was 69% (95% CI, 62-76), distant metastasis-free survival (DMFS) 75% (95% CI, 69-82) and overall survival (OS) 87% (95% CI, 82-92). Among those who underwent surgery and had an evaluable pathological assessment, RFS, DMFS and OS stratified by pathological response are shown in the table. Conclusions: Early nationwide implementation of neoadjuvant ICI in patients with resectable cutaneous melanoma resulted in favourable outcomes that closely mirror those reported in randomized clinical trials. Pathological response N RFS at 24 months% (95% CI) DMFS at 24 months% (95% CI) OS at 24 months% (95% CI) pCR 103 92 (85-100) 93 (86-100) 94 (87-100) near pCR 17 76 (56-100) 83 (64-100) 90 (73-100) pPR 41 83 (71-97) 85 (74-98) 92 (81-100) pNR 90 48 (36-63) 63 (52-78) 81 (70-92)