Combination Therapy With Nivolumab and PD-L1/IDO Peptide Vaccine to Patients With Metastatic Melanoma

Background: Huge advances have been made in the treatment of metastatic melanoma (MM) the past 5 years. Especially immunotherapy has shown promising results. Cancer cells are naturally attacked by cells of the immune system, but can induce a state of tolerance whereby they escape from immune attack. This escape is brought about by many mechanisms. An important one is the programmed death pathway (PD-1/PD-L1). PD-L1 is commonly overexpressed on cancer cells. Interaction of PD-1 on activated T cells and PD-L1 on cancer cells lead to inhibition of the cytotoxic T cells. Another important mechanism is through overexpression of the metabolic enzyme IDO on cancer cells. Activation of IDO also inhibits cytotoxic T cells. Investigators have recently identified spontaneous T cell reactivity against PD-L1 and IDO in the tumor microenvironment and in the peripheral blood of patients with MM and healthy donors. Both IDO and PD-L1 reactive CD8 T cells are cytotoxic and can kill cancer cells and immune regulatory cells in vitro.. Thus boosting specific T cells that recognize immune regulatory proteins such as IDO and PD-L1 may directly modulate immune regulation. Due to distinct mechanisms of action, the combination of treatment with a monoclonal antibody targeting PD-1 (Nivolumab) and a vaccine with peptides against PD-L1 and IDO may have a synergistic effect. Investigators have previously reported a phase I trial where, the IDO peptide was tested in 15 patients with MM in combination with Ipilimumab, and no grade 3-4 toxicity was seen. The PD-L1 peptide is currently being tested in a first-in-man study in patients with multiple myeloma. Methods: A two-step clinical phase I/II trial design will be used, starting out with a pilot study including 6 patients with MM to test feasibility and tolerability. If the treatment is found feasible the study will be extended to a phase II study with 24 patients. The objective is to describe anti-tumor immune responses and objective responses using RECIST 1.1. Patients will be treated with Nivolumab in accordance with standard regimen, which involves outpatient IV infusions every second week as long as there is clinical benefit. The PD-L1/IDO peptide vaccine is given from start of Nivolumab and every second week for the first 6 vaccines and thereafter every fourth week up to 1 year. 15 vaccines will be administered in total. Patients will be followed with clinical controls and diagnostic imaging every 12 weeks. Patients who receive all vaccines will have follow up after 3 and 6 months in parallel with standard of care treatment for Nivolumab.