New Response Criteria Proposed for Immunotherapies

linical investigators are testing the antitumor activity of several immunotherapies in a variety of malignancies.But new data from trials in melanoma patients suggest that the standard criteria used to define tumor response and progression may not adequately reflect patient responses to immunotherapeutic agents.In a worst-case scenario, researchers say, the disconnect between patient responses and the criteria used to evaluate them could cause active drugs to fail in clinical trials and the regulatory process.With these concerns in mind, a group of academic and industry researchers proposed a modification to the standard response criteria, which they presented at the annual meeting of the American Society of Clinical Oncology."This is important to all of us in the field," said Jedd Wolchok, M.D., director of immunotherapy clinical trials at Memorial Sloan-Kettering Cancer Center in New York and a coauthor on the proposal."We don't want to see drugs discarded because the response criteria are inappropriate."Researchers typically use Response Evaluation Criteria in Solid Tumors (RECIST) criteria or modifi ed World Health Organization (mWHO) criteria to defi ne tumor responses and disease progression.Both systems were developed for the evaluation of cytotoxic chemotherapies and rely on tumor shrinkage to indicate antitumor activity.By contrast, in several recent trials that tested an antibody that inhibits CTLA-4, a key immune system checkpoint, some patients appeared to derive long-term survival benefi t from the treatment but showed continued tumor growth initially.By standard criteria, such patients would be classifi ed as having pro-gressive disease and taken off the study drug.