A fusion protein consisting of a fully human monoclonal antibody directed against the endocytic dendritic cell (DC) receptor, DEC-205, linked to the tumor-associated antigen (TAA) NY-ESO-1 with potential immunostimulating and antineoplastic activities. The monoclonal antibody moiety of DEC-205/NY-ESO-1 fusion protein CDX-1401 binds to the endocytic DC receptor, which may result in DC endocytic internalization of this agent, specifically delivering the NY-ESO-1 moiety. DC processing of NY-ESO-1 may boost the immune system to mount a cytotoxic T-lymphocyte response (CTL) against cancer cells expressing NY-ESO-1. NY-ESO-1, a cell surface protein expressed in normal fetal and adult testes, is upregulated in a variety of tumor cell types.