PT-023 - EFFECT OF STEROID SPARING IMMUNOSUPPRESSIVE AGENTS USED IN THE TREATMENT OF IMMUNE RELATED ADVERSE EVENTS ON TUMOR OUTCOMES IN MELANOMA AND NON-SMALL CELL LUNG CANCER

J. Hines¹, S. Syed², J. Hines³, S. Rouhani⁴, P. Reid⁵; ¹University of Chicago Hospitals, ²UT Southwestern, ³University of Chicago, ⁴Massachusetts General Hospital, ⁵University of Chicago Medical Center.

Background: Steroid sparing immunosuppressive agents (SSIAs) are used in the treatment of refractory immune related adverse events (irAEs). The effect of SSIAs on the efficacy of immune checkpoint inhibitors (ICIs) is not well known. Our objective was to compare the outcomes of patients who received corticosteroid monotherapy vs those who received combination therapy with an SSIA for treatment of an irAE.

Methods: A retrospective case-control was performed of patients with melanoma or non-small cell lung cancer aged > 18 years who were treated with >1 ICI at a quaternary care center between 1/1/2016-11/1/2021. Data on cancer outcomes, ICI, irAE, steroids and SSIA related information were extracted from the electronic medical record by four individual physicians. Propensity score full matching was implemented using the matchit function from the R MatchIt package. A propensity score for SSIA treatment was estimated using logistic regression to regress an indicator variable for SSIA treatment on tumor type, tumor stage, and number of prior treatment lines. A time-varying covariate for treatment status was included in regressions to adjust for immortal time bias and non-proportional hazards.

Results: A total of 167 cases were identified. After matching, 127 patients were in the CS cohort and 36 in the SSIA cohort (4 unmatched). In the CS cohort, 88 (66.7%) of patients had melanoma vs 24 (66.7%) of patients in the SSIA cohort. In an adjusted analysis, there was no significant difference in rates of progression free survival (PFS), aHR 0.54 (0.26, 1.11), or overall survival (OS), aHR 0.94 (0.46, 1.96), between the two cohorts.

Conclusion: Our analysis shows no significant difference in PFS or OS in patients with melanoma or NSCLC treated with corticosteroids alone or in combination with SSIAs. Studies with larger cohorts are needed to confirm these findings.