2551 Background: For patients with hormone-refractory prostate cancer (HRPC) treatment options are limited. Immunotherapies based on dendritic cells (DCs) might represent promising alternatives. In a Phase I clinical trial, we evaluated the safety and feasibility of a vaccination with monocyte-derived DCs loaded with a cocktail consisting of HLA-A*0201-restricted peptides derived from prostate cancer-associated antigens (PSA, PSMA, survivin, prostein, trp-p8). Methods: Eight HRPC patients were enrolled in this study (Table). Each patient underwent two leukaphereses, for the isolation of monocytes and subsequent generation of mature DCs. Patients received a total of four vaccinations each with peptide cocktail-loaded DCs at a dose of 1 x 107 cells both intradermally and intravenously every other week. Clinical response was monitored by the determination of the PSA level. The induction of a peptide-specific T-cell response was assessed by ELISPOT analysis. Results: Apart from local erythema and edema at the site of intradermal administration no side effects were noted. Four of eight patients showed a temporary PSA decline. One patient displayed a partial response with a PSA decrease > 50% for seven weeks and further stabilization for five weeks. Stable PSA values or decelerated PSA increases were observed in the three remaining patients. In ELISPOT analyses, three of four PSA responders also showed antigen-specific CD8+ T-cell activation against prostein, survivin and PSMA. Conclusions: The described protocol represents a safe and feasible concept for the induction of clinical and immunological responses. The application of a peptide cocktail derived from different antigens as a novel treatment modality is supposed to allow for the genetic and biologic heterogeneity of PCa. [Table: see text] [Table: see text]
962MO A phase I clinical trial on intratumoral injection of autologous CD1c (BDCA-1)+/CD141 (BDCA-3)+ myeloid dendritic cells (myDC) in combination with talimogene laherparepvec (T-VEC) in patients with advanced pretreated melanoma
