Dendritic Cell Vaccination During Lymphoid Reconstitution

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DESCRIPTION (provided by applicant): Dendritic cells (DC) are potent antigen-presenting cells that have been tested in early phase clinical trials for their ability to prime and amplify tumor antigen-specific T cell responses. The modest results achieved so far suggest that new approaches to DC vaccination are needed. In this proposal, we wish to take advantage of immune homeostasis induced after lymphoid depletion to amplify DC-induced immune responses and achieve immune reconstitution with antigen-specific T cells. A dose ranging study will be performed in which either no, or escalating doses of fludarabine will be followed by intranodally infused peptide-pulsed DC and autologous lymphocyte infusion (ALI) given intravenously to patients with chemotherapy-naive metastatic melanoma. We will determine the toxicities, the immune responses seen to defined melanoma antigens and the impact upon T lymphoid reconstitution in each cohort. Our hypothesis is that DC immunization during lymphoid homeostatic reconstitution will result in greater amplitude and duration of antigen-specific immune responses than DC vaccination alone. DC matured with a cocktail of cytokines shown in vitro to be optimal for T cell stimulation and pulsed with multiple class I and class ll-restricted tumor antigen peptides will be infused into a groin lymph node with intravenous ALI as a "reference" arm, or DC will be given intranodally with ALI after escalating doses of fludarabine given to induce lymphopenia. DC will be infused during lymphoid recovery based on our pre-clinical work, then 1, 3 and 5 weeks later. The goal of the phase I study is to define a tolerable dose of fludarabine with DC and ALI that can be shown to induce maximal antigen-specific class I and ll-restricted T cell responses in immunologic assays. In this phase I study the principal endpoint will be the level and longevity of tumor antigen-specific immune response achieved. Toxicity as well as clinical response will be secondary endpoints. The cohort with the optimal level of immune response will be taken forward in future studies.