The following article features coverage from the Society of Immunotherapy of Cancer (SITC) 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Pseudoprogression with immune checkpoint inhibitors (ICIs) was observed in a cohort of patients with recurrent cervical cancer, including early, delayed, and serial events, according to the results of a study presented at the virtual Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting & Preconference Programs (SITC 2020).

Pseudoprogression has been reported with ICIs, but the etiology is not well understood. This study aimed to evaluate patterns of pseudoprogression among patients with cervical cancer.

The study evaluated 303 patients with recurrent cervical cancer who received balstilimab, an anti–PD-1 antibody, alone or in combination with zalifrelimab, an anti–CTLA-4 antibody, for pseudoprogression. Pseudoprogression was defined as disease progression as measured by RECIST v1.1, followed by stable disease, tumor shrinkage, or disappearance of nonmeasurable lesions for at least 2 tumor assessments. Events of pseudoprogression were categorized as early, which occurred up to 12 weeks of treatment; delayed, which occurred after week 12; and serial, which included at least 2 different pseudoprogression events.

Pseudoprogression was observed among 7% of patients (21 individuals). Among patients who received combination ICIs, early pseudoprogression occurred in 6% and delayed pseudoprogression occurred in 3%. Among patients who received balstilimab alone, 4% of patients developed early, <1% developed delayed, and <1% experienced serial pseudoprogression.


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There was a total of 47 pseudoprogression sites. “Approximately two-thirds occurred in target or nontarget lesions and 33% in new lesions,” David M. O’Mally, DM, of The Ohio State University in Columbus, Ohio, and presenter of the study, said. He added that about 56% of events occurred in lymph nodes.

All pseudoprogression events were followed by clinical benefit, including improvements in disease, performance status, weight stabilization, and decreased pain.

Dr O’Mally said that “the underlying mechanisms of pseudoprogression may include tumor flare and immune-related adverse events, and may mimic progressive disease.” He concluded that the authors are working to further define the underlying mechanisms of pseudoprogression.

Read more of Cancer Therapy Advisor‘s coverage of the SITC 2020 meeting by visiting the conference page.

Reference

O’Malley DM, Feliu WO, Ray-Coquard I, et al. Pseudoprogression patterns: analysis from 2 independent phase-2 studies with immunotherapy for recurrent cervical cancer. Presented at: Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting & Preconference Programs (SITC 2020); November 11-14, 2020. Abstract 267. J Immunother Cancer. 2020;8(Suppl 3):A656–A959.