A Phase IIb Randomized Controlled Trial of the TLPLDC Vaccine as Adjuvant Therapy After Surgical Resection of Stage III/IV Melanoma: A Primary Analysis

BACKGROUND: Melanoma therapy has changed dramatically over the last decade with improvements in immunotherapy, yet many patients do not respond to current therapies. This novel vaccine strategy may prime a patient’s immune system against their tumor and work synergistically with immunotherapy against advanced-stage melanoma. METHODS: This was a prospective, randomized, double-blind, placebo-controlled, phase IIb trial of the tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine administered to prevent recurrence in patients with resected stage III/IV melanoma. Patients were enrolled and randomized 2:1 to the TLPLDC vaccine or placebo (empty yeast cell wall particles and autologous dendritic cells). Both intention-to-treat (ITT) and per treatment (PT) analyses were predefined, with PT analysis including patients who remained disease-free through the primary vaccine/placebo series (6 months). RESULTS: A total of 144 patients were randomized (103 vaccine, 41 control). Therapy was well-tolerated with similar toxicity between treatment arms; one patient in each group experienced related serious adverse events. While disease-free survival (DFS) was not different between groups in ITT analysis, in PT analysis the vaccine group showed improved 24-month DFS (62.9% vs. 34.8%, p = 0.041). CONCLUSIONS: This phase IIb trial of TLPLDC vaccine administered to patients with resected stage III/IV melanoma shows TLPLDC is well-tolerated and improves DFS in patients who complete the primary vaccine series. This suggests patients who do not recur early benefit from TLPLDC in preventing future recurrence from melanoma. A phase III trial of TLPLDC + checkpoint inhibitor versus checkpoint inhibitor alone in patients with advanced, surgically resected melanoma is under development. TRIAL REGISTRATION: NCT02301611. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at (10.1245/s10434-021-09709-1).