Phase I BALLI-01 trial: UCART22 in R/R CD22+ B-ALL

Results from the phase I BALLI-01 (NCT04150497) trial, evaluating UCART22, an allogeneic CD22-directed chimeric antigen receptor (CAR) T-cell therapy, + alemtuzumab in 45 patients with heavily pretreated, relapsed/refractory (R/R) CD22+ B-cell acute lymphoblastic leukemia (B-ALL), were presented by Nitin Jain at the European Hematology Association (EHA) 2026 Congress, June 11–14, 2026, Stockholm, SE. UCART22 was assessed at varying dose levels and under two manufacturing processes (external manufacturing [P1] and internal manufacturing [P2]). The key objectives were to assess the safety and responses of UCART22 and alemtuzumab, to define the recommended phase II dose (RP2D) of UCART22, to define the need for alemtuzumab in the lymphodepletion regimen, and to assess the pharmacokinetics (PK) of alemtuzumab. 

Key data: Overall, Grade ≤3 cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 71% and 17% of patients, respectively. In the dose level 3 (DL3) P2 group (5 × 10⁶ cell/kg; n = 12), CRS and ICANS occurred in 93% and 39% of patients, respectively. One Grade 5 event of treatment-related multiple organ dysfunction syndrome occurred at DL3. The ORR was higher with P2 (64%) vs P1 (34%), with complete remission (CR) / CR with incomplete hematologic recovery (CRi) in 36% vs 28% of patients. The ORRs at DL3 P2 were higher in patients aged ≤50 years with flat dose alemtuzumab vs those aged ≤50 years with low weight-based dose alemtuzumab (100% vs 70%). DL3 P2 was selected as the RP2D. All 7 patients treated at DL3 P2 proceeded to transplant. 

Key learning: UCART22 + alemtuzumab achieved clinically meaningful responses with low rates of Grade ≥3 CRS and ICANS, supporting further investigation of the RP2D in the pivotal phase II trial.