Immune-related adverse events as predictors of response in cancer patients undergoing immunotherapy

To determine the incidence of immune-mediated adverse reactions with and without radiologic manifestations and to correlate them with the response to immunotherapy.

We retrospectively included 79 patients with stage IV lung carcinomas (n=24), renal carcinomas (n=11), or melanoma (n=44) treated with immunotherapy. We evaluated the occurrence of immune-mediated adverse reactions, their radiologic manifestations, and the response pattern according to the immune-related response criteria (irRC). We correlated the presence of immune-mediated adverse reactions with the response pattern.

Immune-mediated adverse reactions occurred in 27.8%, being most common in patients with melanoma (40.9%). In 59.1% of patients with adverse reactions, there were radiologic manifestations such as pneumonitis, colitis, hypophysitis, thyroiditis, or myocarditis. Pneumonitis was the most common radiologic manifestation of immune-mediated adverse reactions, even in asymptomatic patients. The rate of response to immunotherapy was higher among patients who developed immune-mediated adverse reactions than in those who did not (68.2% vs. 38.6%, respectively, χ² 5.58; p=0.018). The rate of favorable responses was higher in patients with radiologic manifestations of immune-mediated adverse reactions than in those without radiologic manifestations (84.6% vs. 44.4%, respectively; p=0.023).

The presence of immune-mediated adverse reactions is associated with a better response to immunotherapy. The association with a favorable response is even stronger in patients with radiologic manifestations of the immune-mediated adverse reactions.