CTLA4 and melanoma: Whereas all naïve controls (n=15) developed melanoma in the brain and died within 35 days after B78 engraftment, 11 of 12 mice previously rendered disease-free by ISV + α-CTLA-4 rejected intracranial B78 melanoma engraftment, resulting in prolonged survival (p<0.001) (figure 2A).