Local Modulation of Immune Receptors to Enhance the Response to Dendritic Cell Vaccination in Metastatic Melanoma

Our proposed study is designed to test the safety of a new vaccine against melanoma. The induction of immune activity against cancers such as melanoma is a promising approach to cancer treatment, but to date, only a few clinically significant immune responses have been seen following vaccine therapy. This is an important problem, since there are very limited treatment options for patients with metastatic melanoma (melanoma that has spread to lymph nodes and organs). Studies suggest that monoclonal antibodies (mAbs) that block inhibitory receptors on immune cells can enhance the immune responses against cancer, but the intravenous injection of such mAbs has caused severe side effects in animals and humans. In our laboratory, we have developed a method to deliver mAbs and other proteins that block such inhibitory receptors locally at the site where immune responses against melanoma proteins are stimulated by vaccination, enhancing anti-melanoma immunity while avoiding the side-effects associated with intravenous injection of these immune modulators. This is achieved by loading dendritic cells, a type of immune cell, with RNA that encodes the immune modulator. The RNA-loaded dendritic cells then make the immune modulatory proteins and release them locally. By mixing these dendritic cells with additional dendritic cells loaded with melanoma proteins, the immune modulators are released at the site where anti-melanoma immune cells are stimulated. In this phase I trial, subjects with metastatic melanoma will undergo the process of leukapheresis, in which white blood cells are removed from the body. Monocytes, a type of immune cell, will then be purified from the white blood cells and cultured under conditions that will change them into dendritic cells. Half of these dendritic cells are then loaded with melanoma antigen RNA, which will lead to the production of melanoma antigen proteins within the dendritic cells. The remaining half of the dendritic cells will be either untreated or loaded with RNA encoding immune modulators so that these dendritic cells will release immune modulators at the site of vaccination. These dendritic cells will be mixed with the melanoma antigen-loaded dendritic cells and injected as a vaccine into lymph nodes. Each subject will receive six weekly injections of their own dendritic cells. Safety and toxicity will be closely monitored. In addition, immune responses against melanoma, as well as clinical responses, will be assessed.