The Impact of Social Determinants of Health on Brexucabtagene Autoleucel Outcomes in Adults with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

Background Brexucabtagene autoleucel (brexu-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR-T) cell therapy approved for adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL). How social determinants of health (SDoH) affect outcomes of adults receiving brexu-cel is unknown. Methods This retrospective multicenter analysis spanning 25 U.S centers included adults (≥18 years) with r/r B-ALL treated with brexu-cel between 2021-2023. Progression-free survival (PFS) and overall survival (OS) were calculated from day of brexu-cel infusion and were not censored for hematopoietic cell transplant (HCT) or maintenance. Univariate and multivariate Cox proportional hazards models were used to evaluate the association of age, sex, pre-apheresis disease burden, and SDoH (referral source, insurance, distance from home to CAR-T site, marital status, and the social deprivation index) with progression-free survival (PFS) and overall survival (OS). The social deprivation index (SDI), a composite measure used to quantify socio-economic variation in health outcomes, with higher SDI indicating greater social disadvantage, was estimated at the zip code level. Results Of the 152 patients who received brexu-cel (Table 1), 57% were male. 51% identified as non-Hispanic White, with the remainder identifying as Hispanic (34%), Asian/Pacific Islander (7%), Black (6%), American Indian/Alaskan Native (1%), or mixed race (1%). A majority (46%) were referred for brexu-cel from private/community-based practices and 62% lived within 50 miles of the CAR-T center (36% lived >50 miles and 2% were unknown). Health insurance coverage included primarily public (49%) and private (42%); no patients were uninsured. High SDI (76-100% percentile) was present in 26%, while 14% had a low SDI (0-25th percentile).In unadjusted analyses, there was no difference in PFS or OS between patients with high versus low SDI; closer distance to the CAR-T site (<50 miles versus >50 miles)) was associated with worse OS (HR 1.96; 95% CI 1.00, 3.84; p=0.05).Multivariate analysis (Table 2) revealed that male sex was associated with inferior PFS (HR 1.98; 95% CI 1.02, 3.85; p=0.04) and OS (HR 2.52; 95% CI 1.09, 5.84; p=0.03). There was no difference in PFS (HR 0.95, 95% CI 0.48-1.88, p=0.88) or OS (HR 0.80; 95% CI 0.33,1.92; p=0.62) when comparing Hispanic and non-Hispanic White patients. Additionally, there was no difference in PFS or OS based on any SDoH, including insurance type, marital status, referral source, caregiver type, and distance to transplant center. Conclusions Survival outcomes appear independent of SDoH. There were comparable outcomes for Hispanic patients compared to non-Hispanic patients. Patients with higher SDI had similar outcomes to those with lower SDI. Continuing to improve access to brexu-cel may improve outcomes for disadvantaged populations with r/r B-ALL.