For instance, engineering anti–CTLA-4 to selectively localize its activity at the tumor site prevented peripheral toxicity (Pai et al, 2019) and treatment with TNF inhibitors concomitantly with CTLA-4 and PD1 antibodies ameliorated colitis while improving antitumor efficacy (Perez-Ruiz et al, 2019). The gene discussed is CTLA4; the disease is colitis.