We investigated whether DBCO–anti–4-1BB with MazNP (TRACER) enhances the efficacy of immunotherapy in the poorly immunogenic B16F10 melanoma syngeneic tumor model, which responds poorly to checkpoint therapies such as single-agent treatment or combinations of anti–4-1BB and anti–CTLA-4 antibodies (28). Here, CTLA4 is linked to neoplasm.