1285P Risk of Immune-Related Adverse Events Associated with Adjuvant Antipd-1/Pdl-1 in Solid Tumors

Immune checkpoint inhibitors targeting PD-1/PD-L1 (IO) have deeply transformed the landscape of treatment of metastatic solid tumors and are likely to shape the adjuvant setting. Balance between safety and efficacy should be considered, especially potential serious adverse events. The aim of this systematic review was to determine the risk of developing serious immune related adverse events (irAEs) in patients treated with IO in the adjuvant setting. We performed a systematic review of the evidence available in Pubmed of all randomized phase II-III clinical trials comparing IO versus placebo or observation in the adjuvant setting published up to March 2022. Protocol was registered in PROSPERO. Odds ratio (OR) of adverse events for all grade and high-grade were calculated. Seven studies involving 5425 patients were included (2876 patients in the IO arm and 2549 in the observation/placebo control group). 19% of patients receiving IO reported an irAE compared to 8,7% in the control arm, and 1 out of 7 patients had a high-grade irAE with IO compared to 1 out of 14 patients in the control arm. The OR in the IO group vs placebo/observation was 3,20 (95% CI, 2,41 – 4,26) in all-grade irAEs; 3,49 (95% CI, 1,82 – 6,69) in high-grade (grade 3-4) irAEs; and 4,17 (95% CI, 1,47 – 11,89) in serious AEs. There was not a statistically significant difference between the incidence of deaths due to irAEs, with an OR 3,66 (95% CI, 0,60 – 22,32). Our study showed that the risk of developing irAEs is a more than three times higher risk of developing an immune-related adverse event in the group of adjuvant antiPD-1/PDL-1 compared to observation/placebo, with no differences in the incidence of deaths. This analysis provides a comprehensive overview of ICI-associated AEs in the adjuvant setting, and these findings may help and guide clinicians in management and decision-making of patients with indication of adjuvant treatment.