It is essential to develop a deeper understanding of radiographic responses to immunotherapy such that clinical benefit is not underappreciated in individual patients and during clinical investigation. With the advent of immunotherapy as an integral component of multidisciplinary solid tumor treatment, clinicians and researchers are confronted by an unfamiliar and novel pattern of radiographic responses to treatment. Enlargement of tumors or even new lesions may not represent progression, but rather reflect what will ultimately evolve into a clinically beneficial response. In addition, the kinetics of radiographic changes in response to immunotherapy treatments may be distinct from what has been observed with cytotoxic chemotherapy and radiation. The phenomenon of pseudo progression has been documented in patients receiving immunotherapeutic agents, such as checkpoint inhibitors and cellular therapies.
CHAI LF, PRINCE E, PILLARISETTY VG, KATZ SC. CHALLENGES IN ASSESSING SOLID TUMOR RESPONSES TO IMMUNOTHERAPY. CANCER GENE THER. 2020;27(7-8):528-538. DOI:10.1038/S41417-019-0155-1