The association between mediators of the receptor for advanced glycation end product (RAGE) axis and immune checkpoint inhibitor (ICI)–induced colitis in patients with melanoma.

9587 Background: Colitis and other gastrointestinal (GI) toxicity are a frequent and occasionally severe form of immune-related adverse events (irAEs) in patients treated with ICIs. To date, no definitive mechanism has been identified, and this area remains an active field of investigation. We hypothesized that activation of the RAGE axis, known to be implicated in inflammatory bowel disease through stimulation of signal transduction targeted by pro-inflammatory RAGE ligands, members of the S100 family and High Mobility Group Box 1 (HMGB1), might be associated with irAE- colitis. Methods: We examined sera from 111 advanced melanoma patients prospectively accrued and followed up at NYULH (treated with anti-PD-L1, n = 44; antiCTL4, n = 23; and combination, n = 44). 24 (22%) developed GI toxicity grade >2. Serum biomarkers of the ligand-RAGE pathways, soluble (s)RAGE, endogenous secretory (es)RAGE, S100B, and HMGB1, were measured in the patients’ sera during ICI treatment. Multivariable ordinal logistic regression analyses with all grades of GI toxicity as the primary outcome for all the recorded covariates (including serum biomarkers, clinical covariates) were performed. We then used ordinal multivariable logistic regression with stepwise variable selection. Similar analyses with GI toxicity as a binary outcome ((≥grade 1 vs no toxicity) were also conducted. Only those variables that jointly contributed to the odds of developing toxicity were included in the final stepwise model. No adjustments for multiplicity were included. As sRAGE and esRAGE are highly correlated (r = 0.86), esRAGE concentrations were not used in the joint models. Results: A significant association between GI toxicity and concentrations of sRAGE and S100B was identified. The final stepwise multivariable logistic model includes only sRAGE and S100B. The odds of having a one level increase in GI toxicity grade increase 1.100 times (95% CI: 1.008, 1.199; p = 0.029) for each unit decrease of sRAGE ( = sRAGE/100). The odds of a one level increase in GI toxicity increase 1.059 times (95% CI: 1.004, 1.116; p = 0.035) for each unit increase of S100B ( = s100B/100). All other analyses yielded comparable results. In contrast, concentrations of HMGB1 and other clinical covariates, including response and treatment category, were not associated with GI toxicity. Conclusions: Mediators of the RAGE axis, specifically sRAGE and S100B, might have a role in GI toxicity in patients receiving ICIs. The ligand-RAGE axis may be a novel target for irAE therapies for patients receiving ICIs to mitigate the severity of GI toxicity.