CTLA4 and Autoimmunity: Another study showed that administration of a CTLA-4 inhibitor in combination with an antimelanoma vaccine resulted in 14 patients developing grade 3 or 4 autoimmune toxicity with 36% of those patients experiencing a clinical response compared to 5% in those patients experiencing no autoimmunity.8 A single-institution study showed a significantly higher clinical benefit rate in patients on a CTLA-4 inhibitor who developed grade 3 or 4 irAE (60%) compared with those with grade ≤2 irAE (22%).9