Clarification of Definitions of Hyperprogressive Disease During Immunotherapy

To the Editor In their recent Original Investigation, Kas et al¹ compared 5 different definitions of hyperprogressive disease (HPD) based on tumor growth rate (TGR) or tumor growth kinetics during immunotherapy for non–small cell lung cancer (NSCLC), using exclusively changes in target lesions measured in a prebaseline tumor assessment and 2 different time points: baseline and first tumor evaluation. For that purpose, they analyzed patients with advanced NSCLC treated with immune checkpoint inhibitor (ICI) treatment. The authors’ conclusion suggests that an increase in the TGR in patients receiving ICI therapy should be defined as HPD, and they propose a new definition: an increase greater than 20% by Response Evaluation Criteria in Solid Tumors, version 1.1 criteria and ΔTGR of greater than 100. However, we would like to highlight some additional aspects that should not be neglected.