Background: Brexu-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for pts ≥18 y with R/R B-ALL in the US (≥26 y in the EU). In the 3-y follow-up of ZUMA-3, median overall survival (OS) was 25.6 mo (N=78). Survival benefit was seen regardless of age, prior treatment, or subsequent allogeneic stem cell transplant (sub alloSCT) status (Shah et al. ASCO 2023. #7023). Here we report 4-y survival outcomes for ZUMA-3. Methods: Eligible pts (≥18 y) had R/R B-ALL and received brexu-cel (1×10⁶ CAR T cells/kg) after leukapheresis and lymphodepleting chemotherapy. The primary endpoint was overall complete remission (CR)/CR with incomplete hematologic recovery (CRi) rate per independent review with OS as a key secondary endpoint. Descriptive statistics are reported for post hoc exploratory subgroup analyses. Results: As of July 23, 2023, median follow-up time in Phase 1 and 2 pts who received the pivotal dose of brexu-cel (N=78) was 53.6 mo (range 44.7-82.3). Median OS (95% CI) was 25.6 mo (16.2-60.4) in all treated pts and 47.0 mo (23.2-not estimable [NE]) in pts with CR/CRi (n=57). In pts <26 y (n=15), median OS (95% CI) was 23.2 mo (9.0-NE) and was 26.0 mo (15.9-NE) in pts ≥26 y (n=63). Median OS (95% CI) in pts with 1 prior therapy (n=15) was 60.4 mo (7.6-NE) and was 25.4 mo (15.9-47.0) in pts with ≥2 prior therapies (n=63). Medians for OS (95% CI) in pts with (n=38) and without (n=40) prior blinatumomab (blina) were 15.9 (8.3-26.0) and 60.4 mo (18.6-NE), respectively. Median OS (95% CI) was 36.3 mo (10.2-NE) in responders who went on to sub alloSCT (n=14) and 60.4 mo (23.2-NE) in those who did not (n=43). The 48-mo OS rate was 40% (95% CI, 28-52) in all pts but appeared lower in pts with prior blina (24%; Table). No new adverse events or deaths occurred since the prior analysis. Grade ≥3 infection rates since the start of study appeared higher in pts <26 y and in pts with prior blina (Table). Rates of non-relapse mortality (NRM) and relapse-related mortality (95% CI) at 48 mo were 25% (15-37) and 34% (24-45; N=78), respectively. Of note, 6/17 NRM events (35%) occurred in pts with sub alloSCT. Conclusions: After >4 y follow-up, pts in ZUMA-3 continued to experience OS benefit regardless of age, prior therapy, or sub alloSCT status, though pts with prior blina had a numerically lower 48-mo OS rate. Small subgroups and unbalanced pt characteristics limit interpretation of these results. No new safety signals were observed. Further studies are needed to fully assess the impact of age, prior therapies, and sub alloSCT on outcomes after brexu-cel. Clinical trial information: NCT02614066.