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World J Clin Oncol. May 24, 2021; 12(5): 323-334
Published online May 24, 2021. doi: 10.5306/wjco.v12.i5.323
Immune response evaluation criteria in solid tumors for assessment of atypical responses after immunotherapy
Davide Ippolito, Cesare Maino, Maria Ragusi, Marco Porta, Davide Gandola, Cammillo Talei Franzesi, Teresa Paola Giandola, Sandro Sironi
Davide Ippolito, Cesare Maino, Maria Ragusi, Marco Porta, Davide Gandola, Cammillo Talei Franzesi, Teresa Paola Giandola, Department of Diagnostic Radiology, H. S. Gerardo Monza, School of Medicine, University of Milano-Bicocca, Monza 20900, Italy
Sandro Sironi, Diagnostic Radiology, University of Milano-Bicocca, Bergamo 24127, Italy
Author contributions: All authors contributed equally to this work and have read and approved the final manuscript.
Conflict-of-interest statement: All authors declare no conflict-of-interest.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Davide Ippolito, MD, Adjunct Professor, Doctor, Department of Diagnostic Radiology, H. S. Gerardo Monza, School of Medicine, University of Milano-Bicocca, Via Pergolesi 33, Monza 20900, Italy. davide.atena@tiscali.it
Received: January 24, 2021
Peer-review started: January 24, 2021
First decision: March 8, 2021
Revised: March 23, 2021
Accepted: April 23, 2021
Article in press: April 23, 2021
Published online: May 24, 2021
Abstract

In 2017, immune response evaluation criteria in solid tumors (iRECIST) were introduced to validate radiologic and clinical interpretations and to better analyze tumor’s response to immunotherapy, considering the different time of following and response, between this new therapy compared to the standard one. However, even if the iRECIST are worldwide accepted, to date, different aspects should be better underlined and well reported, especially in clinical practice. Clinical experience has demonstrated that in a non-negligible percentage of patients, it is challenging to determine the correct category of response (stable disease, progression disease, partial or complete response), and consequently, to define which is the best management for those patients. Approaching radiological response in patients who underwent immunotherapy, a new uncommon kind of target lesions behavior was found. This phenomenon is mainly due to the different mechanisms of action of immunotherapeutic drug. Therefore, new groups of response have been described in clinical practice, defined as “atypical responses,” and categorized into three new groups: pseudoprogression, hyperprogression, and dissociated response. This review summarizes and reports these patterns, helping clinicians and radiologists get used to atypical responses, in order to identify patients that respond best to treatment.

Keywords: Response evaluation criteria in solid tumors, Tumor response, Pseudoprogression, Hyperprogression, Dissociated response

Core Tip: Atypical responses are frequent events in the immunotherapy era. On these bases, it is fundamental to summarize and recap the most common and important response manifestations to help clinicians in everyday practice. Here, we present the three most common clinical and radiological patterns of response to immunotherapy: pseudoprogression, hyperprogression, and dissociated response, reporting important studies to identify the different behavior and guarantee the best management, strengthening the communication skills between specialists.