CTLA4 and metastatic melanoma: The four public immunotherapy cohorts included (1) the Hellmann cohort of 75 NSCLC patients treated with anti-PD-1 plus anti-CTLA4; (2) the Allen and Snyder cohort, a pooled analysis of two cohorts of 174 metastatic melanoma patients treated with anti-CTLA4; and (3) the MSKCC cohort of 1661 pan-cancer patients treated with anti-PD-(L)1 or anti-CTLA4.