In 4 melanoma patients treated with anti-CTLA4, tumour-specific CD4 T-cell lines established from samples collected post-ipilimumab treatment showed superior in vitro lysis of NY-ESO-1+-expressing tumour cell lines compared to pre-treatment CD4 T cells (82), suggesting ICB induction of a CD4 CTL phenotype. The gene discussed is CTLA4; the disease is neoplasm.