These inhibitors and derivative compounds block growth and vascularization of breast, colorectal, head/neck, melanoma, and prostate tumors as monotherapy, and overcome resistance to anti-CTLA-4 or anti-PD-1 immunotherapy, with an aggregate complete response rate of over 50%, through reprogramming of the tumor immune cell microenvironment. Here, CTLA4 is linked to prostate neoplasm.