Curative effect assessment of immunotherapy for non-small cell lung cancer: The "blind area" of Immune Response Evaluation Criteria in Solid Tumors (iRECIST).

Immunotherapy has considerably changed the treatment of lung cancer. As immunotherapy has a special mechanism of action, the disease remission that it can induce is unique. Recently, Immune Response Evaluation Criteria in Solid Tumors (iRECIST), which focus on assessing the apparent curative effect of immunotherapy, have become widely accepted. Based on iRECIST criteria, if the response to immunotherapy is determined to be immunity-confirmed progressive disease or immunity-unconfirmed progressive disease, and the Eastern Cooperative Oncology Group score is worse than before treatment, immunotherapy should be discontinued. We report two immunity-confirmed progressive disease cases after pembrolizumab treatment and one immunity-unconfirmed progressive disease case after nivolumab treatment. All three patients benefited from continued immunotherapy, which indicates that the iRECIST criteria may have limitations in assessing the efficacy of immunotherapy for non-small cell lung cancer patients.