Retrospective analysis on association of ABO blood type and immune checkpoint inhibitor response.

2596 Background: The presence or lack of a collection of antigenic cell surface markers on red blood cells makes up the ABO blood groups that contribute to various immunogenic neoantigens. Variations in the T-cell diversity and HLA haplotype with different blood types might affect a patient's response to Immune checkpoint inhibitors (ICIs). However, the association between the ABO blood type and ICIs is not well studied. Methods: We did a retrospective observational study to investigate the influence of ABO blood groups on patients receiving ICIs at the University of Vermont Cancer Centre. We examined the medical records of people who received ICIs as first-line therapy between January 2017 and June 2022 and collected demographic data, including age, sex, ethnicity, cancer stage, type and metastasis. We looked at overall survival and the occurrence of immune-related adverse events (irAEs) in different blood type subgroups and calculated relative risks. Results: A total of 288 cases were identified, out of which 169 had documented blood type, including 75 with A, 19 with B, 72 with O and 3 with AB blood type. The mean age was 63.71 years (Standard deviation (SD): 11.52), 58.6% were males, and ethnicity was 94.7% White, 1.2% Asian and 0.6% Hispanic. Lung cancer was most commonly identified at 41%, and 60% of total cancers were stage 4. The median ECOG status was 1 and the Charlson comorbidity index was 6. 36% of cases developed irAEs, whereas mortality was 39% during the study period. The relative risk of irAEs with blood type A and B compared to O was 0.89 and 0.83, respectively but wasn't statistically significant. The relative risk of irAEs of AB compared to O blood type was statistically significant at 2.63 (CI: 1.95-3.54). The relative risk of death in A and B blood types compared to O wasn't statistically significant. No patients in the AB blood group died. Conclusions: Clinically significant association wasn't found between different blood types and irAEs or mortality except for the increased risk of irAEs with AB compared to O. With the rapidly growing use of ICIs, prospective trials are needed to better understand the true risk of developing irAEs in patients with AB blood type. [Table: see text]