Retrospective study evaluating immune-related adverse events in cancer patients treated with pembrolizumab

Pembrolizumab has been on the market for several years, but most of the safety data is based on clinical trials with limited literature evaluating post-marketing immune-related adverse events (irAEs) associated with its use. This study aimed to evaluate the characteristics of irAEs associated with pembrolizumab.

We included adult patients who had received pembrolizumab between January 2016 and December 2020. The patient electronic profiles and the pharmacy adverse event reporting system were reviewed to identify adverse events. Patients were followed from the start of treatment until 12 months after the last dose, end of the study, or death. The characteristics of the patients and the irAEs were recorded. Univariate and multivariate logistic regression analyses were performed to identify variables associated with the development of irAE.

During the study period, 223 patients and 1601 cycles of pembrolizumab were evaluated. A total of 67 irAEs were reported in 58 patients. The median age was 53 years (range 18-84), and most patients were males (75%) with metastatic lung cancer (62%). The most common irAEs were respiratory (30%), followed by gastrointestinal (25%), endocrine (24%), and dermatologic (21%). Among the reported irAEs, 28 were associated with hospital admission, 15 required long-term treatment, and 9 resulted in pembrolizumab discontinuation. In logistic regression, there were no significant predictors associated with irAE.

Respiratory irAEs were the most common in our population. We were unable to identify predictors of irAE in this cohort. Further studies are necessary to identify predictors of adverse events.