Vaccination with autologous dendritic cells loaded with autologous tumor lysate or homogenate combined with immunomodulating radiotherapy and/or preleukapheresis IFN-alpha in patients with metastatic melanoma: a randomised "proof-of-principle" phase II study

Background: Vaccination with dendritic cells (DC) loaded with tumor antigens elicits tumor-specific immune responses capable of killing cancer cells without inducing meaningful side-effects. Patients with advanced melanoma enrolled onto our phase II clinical studies have been treated with autologous DC loaded with autologous tumor lysate/homogenate matured with a cytokine cocktail, showing a clinical benefit (PR + SD) in 55.5% of evaluable cases to date. The beneficial effects of the vaccine were mainly restricted to patients who developed vaccine-specific immune response after treatment. However, immunological responses were only induced in about two-thirds of patients, and treatments aimed at improving immunological responsiveness to the vaccine are needed. Methods/Design: This is a phase II, "proof-of-principle", randomized, open-label trial of vaccination with autologous DC loaded with tumor lysate or homogenate in metastatic melanoma patients combined with immunomodulating RT and/or preleukapheresis IFN-alpha. All patients will receive four bi-weekly doses of the vaccine during the induction phase and monthly doses thereafter for up to a maximum of 14 vaccinations or until confirmed progression. Patients will be randomized to receive: (1.) three daily doses of 8 Gy up to 12 Gy radiotherapy delivered to one non-index metastatic field between vaccine doses 1 and 2 and, optionally, between doses 7 and 8, using IMRT-IMAT techniques; (2.) daily 3 MU subcutaneous IFN-alpha for 7 days before leukapheresis; (3.) both 1 and 2; (4.) neither 1 nor 2. At least six patients eligible for treatment will be enrolled per arm. Daily 3 MU IL-2 will be administered subcutaneously for 5 days starting from the second day after each vaccine dose. Serial DTH testing and blood sampling to evaluate treatment-induced immune response will be performed. Objective response will be evaluated according to immune-related response criteria (irRC). Discussion: Based upon the emerging role of radiotherapy as an immunologic modifier, we designed a randomized phase II trial adding radiotherapy and/or preleukapheresis IFN-alpha to our DC vaccine in metastatic melanoma patients. Our aim was to find the best combination of complementary interventions to enhance anti-tumor response induced by DC vaccination, which could ultimately lead to better survival and milder toxicity.