Long-term follow-up of adjuvant DC-CIK following high-dose IFN versus high-dose IFN or anti-PD1 for resected acral/cutaneous melanoma.

e21571 Background: Novel individualized neoantigen vaccine showed durable survival benefit when combined with anti-PD-1(aPD-1) vs aPD-1 alone. Dendritic cell combined with cytokine-induced killer (DC-CIK) cell was classic cellular antitumor therapy. However, whether DC -CIK prolong survival in resected melanoma remains unknown. We conducted this single center, retrospective study designed to compare the efficacy of relapse free survival (RFS) and overall survival (OS) of DC+ interferon (IFN), IFN alone, and aPD-1 alone in stage III resected acral/cutaneous melanoma. Methods: This retrospective observational study included patients who initiated adjuvant DC+IFN， IFN, or aPD-1 for stage III resected acral/cutaneous melanoma between 01/01/2010 and 12/31/2022. Other inclusion criteria included age≥18 years old, received ≥1 dose treatment, well-documented follow-up records. DC were loaded with allogeneic melanoma lysate. Adjuvant treatment were given in one-year time frame for all three arms. Demographics, date of relapse and date of death were also included. The endpoints included RFS, and OS. Kaplan-Meier methods and Cox regressions were used to estimate median RFS, OS and HR. Results: With follow-up until 12/31/2024. We identified 376 patients whose demographic data are summarized, with 196 (51.9%) acral melanoma and 182(48.1%) cutaneous melanoma pts. AJCC 8 th ed stage was IIIA, IIIB, IIIC and IIID in 25 (6.6%), 150 (39.9%), 134 (35.6%) and 67(17.9%) patients, respectively. Two hundred and thirty-five patients had documented gene test, 78(23.5%) exhibit gene alteration, including BRAF/NRAS/KIT: 40/28/10. Among all the patients, 99 received treatment with DC+IFN，161 with IFN，and 116 with aPD-1. Median overall survival (OS) for patients treated with aPD-1 was not reached (NR) for inadequate follow-up time, while median OS for patients treated with DC+IFN or IFN was 53.7 months (mo) (95% CI 36.1-77.0) and 34.2 mo (95% CI 17.6-48.4), respectively(p = 0.04). Median RFS were 19.3 mo (95% CI 12.5-26.1), 10.8 mo (95% CI 8.4-15.8) and 12.1 mo (95% CI 6.9 -14.7) for DC+IFN, IFN and aPD-1 arms, with a trend of improved RFS in patients received DC+IFN vs IFN (log-rank p = 0.08). Conclusions: Patients with stage III resected acral/cutaneous melanoma treated with DC+IFN had longer survival compared to those treated with IFN alone. Future research is needed to optimize individualized immunotherapy for pts with stage III resected acral/cutaneous melanoma.