Clinical and Immunological responses in patients with malignant melanoma treated with a dendritic cell-based vaccine. Preliminary report from a multi-institutional phase II clinical trial

3004 Background: We have previously reported that vaccination with IDM therapeutic vaccine (IDD-3/Uvidem [Uvidem is co-developed with SANOFI-AVENTIS]) composed of dendritic cells (DC) loaded with three allogeneic lysates from tumor cell lines can elicit immune and anti-tumor responses. We describe here the preliminary results from a phase II clinical trial in metastatic melanoma patients. Methods: DC-MEL-202 is a single arm, two-stage phase II trial designed to evaluate clinical and immunological activities and the safety of a multivalent DC vaccine in patients with in-transit or low volume metastatic melanoma. There was no HLA restriction. Autologous DC were generated, under GMP conditions, from monocytes cultured in GM-CSF and IL-13, loaded with three allogeneic melanoma tumor lysates (M44, SK-MEL 28 and COLO 829) and matured with a combination of bacterial extract (FMKP) and IFN-γ, generating up to 15 doses of the vaccine containing 25x106 DC. Patients received six bi-weekly and two 6-weekly injections (id and sc). Clinical responders were eligible to receive additional doses. Immune response against tumor-associated antigens (TAA) peptides was assessed, at several time points, by detection of IFN-γ producing cells by flow cytometry Results: 33 patients were treated. To date: Vaccination is well tolerated with toxicity limited to mild events (only one possibly related SAE, age-related macular degeneration, was reported). Clinical response (RECIST): 6 patients showed evidence of clinical benefit (1CR, 1PR and 4 SD) with duration of response ranging from 7.5 to 22 months. Assessment of pathological response in target sites in 2 pts (1 PR, 1 SD) showed no residual disease.. 23/33 patients are still alive with a mean follow-up of 11mo (range 3–22mo). Mature data of PFS and OS will be presented. Immune response: 21 (84 %) out of 25 evaluated patients showed detectable TAA-specific CD8+ T cells with ten showing boosted or appearance of anti-TAA specific CD8+ T cells. Conclusions: Vaccination with IDD-3/Uvidem is safe and can elicit tumor specific CD8+ T cells not limited to HLA-A2+ patients. Substantial clinical benefit warrants further development of IDD3. No significant financial relationships to disclose.