To evaluate antitumor responses to chemotherapeutic agents, investigators would typically rely upon Response Evaluation Criteria in Solid Tumors (RECIST) or modified WHO criteria, which do not comprehensively capture responses with immunotherapeutic agents. In the December 1, 2009, issue of Clinical Cancer Research, Wolchok and colleagues reported their development of novel criteria, designated "Immune-related Response Criteria" (irRC), designed to better capture the response patterns observed with immunotherapies. Broad use of the irRC since then has allowed for a more comprehensive evaluation of immunotherapies in clinical trials, indicating that their concepts can be used in conjunction with either RECIST or WHO, and has shown irRC to be a powerful tool for improved clinical investigation. See related article by Wolchok et al VSports手机版. , Clin Cancer Res 2009;15(23) December 1, 2009;7412-20. .