Clinical outcomes of cytomegalovirus infection among patients receiving chimeric antigen receptor T cell therapy.

7021 Background: Chimeric antigen receptor T (CAR-T) cell therapy is a transformative treatment for hematologic malignancies, including multiple myeloma (MM), non-Hodgkin lymphoma (NHL), and acute leukemia (AL). Despite its success, CAR-T therapy is associated with significant toxicities and an increased risk of infections, particularly cytomegalovirus (CMV) infection. CMV infection in CAR-T recipients has been linked to increased non-relapse mortality (NRM) and prolonged hospital stays; however, comprehensive data on its clinical impact remains limited. This study aimed to evaluate the clinical impact of CMV infection on outcomes in CAR-T therapy recipients. Methods: This retrospective cohort study utilized the HCUP-National Readmission Database (NRD) 2021 database to analyze adult hospitalized patients (≥18 years) who underwent CAR-T cell therapy for MM, NHL, or AL in the USA. Patients with a prior CMV diagnosis or discharged in the last three months of 2021 were excluded. Propensity score matching (PSM) was applied to balance baseline characteristics, and weighted estimates were used for outcome analysis. The primary outcome was all-cause mortality within three months post-discharge. Secondary outcomes included length of hospital stay (LOS) and CAR-T-related complications. Results: A total of 1806 hospitalizations met the inclusion criteria. The mean age was 61.9 years, with a male majority of 64.4%. The underlying disorders were NHL (73.7%), MM (21.6%), and AL (4.7%). The incidence of CMV infection during the index hospitalization was 2.2%, increasing to 4.2% within three months post-CAR-T therapy. Matched analysis showed higher three-month mortality in CMV-infected patients (15.8%) compared to non-CMV patients (2.5%) (risk ratio 6.32, 95% CI: 1.46-27.30, p=0.004). CMV-infected patients had a significantly longer mean LOS (41.5 vs. 15.9 days, adjusted mean difference 15.5 days, 95% CI: 6.7-24.2, p=0.001). CMV infection was significantly associated with encephalopathy (risk ratio 13.21, 95% CI: 1.66-105.2, p=0.015), while other complications such as cytokine release syndrome (CRS), AKI, and transaminitis did not show a statistically significant association. Conclusions: CMV infection in CAR-T cell therapy recipients is associated with increased mortality, prolonged hospitalization, and risk of encephalopathy. These findings underscore the need for vigilant CMV surveillance and targeted management strategies to improve patient outcomes.