1100: Associations Between Pre-existing Autoimmunity and CAR T Cell Therapy Toxicity for Cancer Treatment: A Nationwide Retrospective Cohort Study

Background/Purpose: Chimeric antigen receptor (CAR) T cell therapy is being investigated to treat individuals with autoimmune diseases. Data regarding the safety of CAR T cell therapy in this population is limited. We aimed to assess whether pre-existing autoimmune disease was associated with an increase in major toxicity or hospital length of stay (LOS) among patients receiving CAR T cell therapy for treatment of hematologic cancer.

Methods: This retrospective cohort study utilized nationwide United States data from the National Inpatient Sample (2021–2022) to investigate in-hospital outcomes in adult patients receiving CAR T cell therapy. The primary outcome for the study was a composite of major toxicity, defined as the occurrence of at least one of the following: cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), hemophagocytic lymphohistiocytosis (HLH), sepsis, pneumonia, intubation, acute kidney injury, or neutropenia. Secondary outcomes included each individual component of the primary outcome, in-hospital mortality, hospital length of stay (LOS), and tocilizumab use. Comparisons were drawn between patients with and without pre-existing autoimmune disease, identified using International Classification of Diseases, Tenth Revision (ICD-10) codes for common rheumatic, gastrointestinal, endocrine, dermatologic, and neurologic autoimmune diseases. A multivariable regression model with adjustment for age, sex, race, cancer type, and comorbidities assessed associations with hospital LOS, major toxicity, and inpatient mortality.

Results: Among 1,321 patients receiving CAR T cell therapy, 62 (4.7%) had a pre-existing autoimmune disease (Table 1), most commonly rheumatologic (50.0%) or gastrointestinal (19.4%). The median hospital LOS among all patients was 14 days (IQR 10-19). Patients with pre-existing autoimmune disease had a significantly shorter hospital LOS compared to patients without autoimmune disease (mean reduction of 2.1 days, 95% confidence interval [CI] 0.5, 3.6; Tables 2 and 3). Major toxicity was observed in 78.0% of all patients and occurred less frequently in patients with pre-existing autoimmune disease than in patients without (67.7% vs 78.6%; adjusted odds ratio 0.55, 95% CI 0.31, 0.99). Rates of CRS and ICANS were numerically lower in patients with pre-existing autoimmunity than in patients without (54.8% vs 61.4% and 21.0% vs 24.9%, respectively), while rates of HLH and neutropenia were similar between groups (1.6% vs 1.4% and 37.1% vs 37.4%, respectively). Tocilizumab use (11.3% among those with preexisting autoimmune disease and 8.7% among those without) and inpatient mortality (3.2% and 2.9%, respectively) were not statistically different between groups.

Conclusion: Patients with pre-existing autoimmune disease had shorter hospital stays and lower risk of major toxicity following CAR T cell therapy for cancer treatment. This nationwide study offers reassurance as to its safety in this population while providing additional data for research studies of CAR T cell therapy to treat autoimmune diseases.