Abstract
Prolonged cytopenias are a well-recognized complication following CAR-T therapy. Autologous SCB offers a potential strategy to promote fast hematologic recovery. We conducted a retrospective multi-institutional comparing outcomes of SCB versus supportive care alone in patients with prolonged cytopenias after CAR-T infusion. Patients were included if they received SCB within 1 year following commercial CAR-T between 6/2021 and 3/2024. To identify matched controls, we reviewed 590 CAR-T recipients and selected patients with ANC and platelet thresholds representing the 75th percentile of cytopenia severity in the SCB cohort. Hematologic recovery in the SCB cohort was assessed using CIBMTR engraftment criteria. For the non-SCB (nSCB) group, cell counts were analyzed cross-sectionally at day 60 and 90 post-CAR-T and compared to the SCB cohort with Kruskal-Wallis tests. Progression-free survival (PFS) and overall survival (OS) were evaluated using Kaplan-Meier methods. Of 590 patients, 91 patients (15.4%) developed prolonged cytopenias, 39 of whom received SCB. Median CD34+ cell dose was 2.9 million/kg (range: 1.8-23.6) administered at a median of 53 days post-CAR-T (range 24-265). All but one patient (97.4%) in the SCB group achieved hematologic recovery, with median time to recovery of 24 days (range 9-87). No new toxicities attributable to SCB were observed. On day 90 post CAR-T infusion, SCB patients had higher median Hb (10.6 vs. 8.7g/dL, p = 0.002), and platelet counts (135 vs. 35K/L (p < 0.001). After a median follow-up period of 12.6 months in the SCB cohort and 11.6 months in the nSCB arm, the mPFS was 11.0 months and 8.2 months, respectively. Median OS was not reached vs. 12.3 months in the SCB vs. nSCB groups, respectively. Overall, SCB lead to rapid and successful hematologic outcomes in nearly all patients. Compared to matched controls, Hb and platelets were significantly improved by day 90 post-CAR-T infusion.