Sorry, you're absolutely right. I should say 'many', not 'most', my comment was hasty. It varies with the therapy and only a minority of patients fail because of adverse immune events, and the drug matters - ipilimumab (anti-CLTA4) had 10-15% severe immune-related adverse events, whereas anti-PD1 is much better tolerated (probably because the immune checkpoint is later). Combination therapies (ipi + nivo) have much higher adverse event rates, unsurprisingly.
