Introduction: Chimeric antigen receptor T (CAR-T) cell therapy has traditionally been administered in the inpatient (inpt) setting. Several studies have established that outpatient (outpt) CAR-T administration can have a favorable safety profile and lower financial toxicity. However, it's unclear if race plays a role in outcomes following outpt CAR-T administration.

Based on the 2020 census, 78% of the population of Detroit identify as black or african american. However, numerous studies have also shown that black patients (pts) are more likely to live in areas with lower socioeconomic status, characterized by access to a vehicle, telephone line, and unemployment. Assari et al suggested in 2024 that in predominantly black cities, racial disparities are actually attenuated. Nevertheless, safe outpt CAR-T administration relies on exceptional caregiver support, access to transportation and health literacy. In this study we aim to characterize impact of race on the outcomes of CAR-T in a socioeconomically underprivileged area.

Methods: We collected data from all pts who received CAR-T therapy for diffuse large B-Cell lymphoma (DLBCL) and multiple myeloma (MM), from May 2016 to September 2024 at Karmanos Cancer Institute in Detroit, Michigan.

Baseline pt characteristics were summarized using counts and percentages for categorical variables, and medians with ranges for continuous variables. Group comparisons based on inpt versus outpt status and black versus non-black race were separately performed using the chi-square test or Fisher's exact test for categorical variables, and the Wilcoxon rank-sum test for continuous variables. Similar analyses were conducted to separately compare black versus non-black pts within the inpt and outpt care settings. Overall survival (OS) was defined as the time from CAR-T administration to death from any cause. Relapse-free survival (RFS) was defined as the time from CAR-T administration to documented relapse or death, whichever occurred first. Kaplan–Meier methods were used to estimate survival distributions for OS and RFS. Follow-up time was estimated using the reverse Kaplan–Meier method. Survival distributions were compared using the log-rank test. The proportional hazards assumption was evaluated using Schoenfeld residuals. For RFS group comparisons by race within the inpt setting and OS group comparison by race within outpt, the proportional hazard was violated. In these cases, survival modeling was conducted using the weighted Cox regression model. Where the proportional hazards assumption was held, Cox proportional hazards regression was used to derive hazard ratios.

Results: During the study period, 174 pts received CAR-T. 143 pts were treated inpt, and 31 pts were treated outpt. Stratified by race, 148 pts identified as non-black, and 26 pts identified as black. MM was statistically more common in black pts (73.1%), while DLBCL was more common in non-black pts (64.9%), p= <0.001. Black pts had a statistically significantly higher incidence of kidney disease (30.8%) compared to non-black pts (10.8%), p = 0.012 at time of CAR-T treatment. Overall, there was no difference in OS or RFS between black and non-black pts. Median follow up was 1.76 years (95% CI 1.45-2.17) and 2.36 years (95% CI 1.39-NR) for non-black and black pts, respectively. The median OS was 3.1 years (95% CI, 2.15 to NR) and 2.59 years (95% CI, 1.97 to NR) for non-black and black pts, respectively, and was not statistically significantly different (HR 0.95, 95% CI 0.48-1.86, p=0.88). Similarly, the median RFS was 1.48 years (95% CI, 0.94 – 3.12) and 2.59 years (95% CI, 0.61 to NR) for non-black and black pts respectively, and was not statistically significantly different (HR 0.84, 95% CI, 0.45-1.54, p= 0.57).

Within the outpt cohort, median follow up was 1.42 years (95% CI, 1.00 to NR) and 1.39 (95% CI, 1.01 to NR) for non-black and black pts respectively. The median OS is 3.38 years (95% CI, 1.48 to NR) and 2.30 years (95% CI, 2.00 to NR) for non-black and black pts respectively, and was not statistically significant (HR 1.27, 95% CI (0.58-2.78, p = 0.55). Similarly, within the outpt cohort, there was no statistically significant difference in RFS between non-black and black pts.

Conclusions: Race did not impact post CAR-T cell outcomes in pts who were treated for MM and DLBCL. Importantly, race didn't affect outcomes in patients in the outpt cohort, despite higher incidence of renal dysfunction in black pts.

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2025
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