Abstract
BACKGROUND: Primary analysis of the phase I/II clinical trial combining pembrolizumab with all-trans retinoic acid (ATRA) for patients with metastatic melanoma showed a median progression-free survival (PFS) of 20.3 months and median overall survival (OS) not reached. OBJECTIVE: Report 5-year OS and PFS rates. DESIGN: In this single-center, single-arm trial (NCT03200847), 24 anti-PD-1 naïve patients with metastatic melanoma were enrolled between 10/2017 and 07/2020. METHODS: The Kaplan-Meier method was used to estimate OS and PFS. RESULTS: At data cutoff (May 14, 2024), all patients had completed treatment, and 58% (n = 14) remained alive with a median follow-up of 48 months. The updated 5-year OS rate is 54.7% (95% confidence interval (CI): 36.4-82.1), and the 5-year PFS is 36.1% (95% CI: 21.0-62.2), with 33% (n = 8) having an ongoing complete response. CONCLUSION: These results underscore the long-term clinical benefit of combining anti-PD-1 with ATRA, with survival rates comparable to anti-PD-1/combinations but with lower toxicity.