UCART19: the first gene-edited, donor-derived CAR-T cells in children and adults with relapsed B-cell ALL
Off-the-shelf CAR-T cells made from a healthy donor, gene-edited to avoid rejection and graft-versus-host disease, produced remission in 14 of 21 patients with relapsed ALL.
This report pooled two phase 1 studies (PALL in 7 children and CALM in 14 adults) of UCART19, allogeneic CD19 CAR-T cells from healthy donors in which TALEN gene editing disrupted the T-cell receptor alpha constant gene (to prevent graft-versus-host disease) and CD52 (to allow alemtuzumab in lymphodepletion). Patients with relapsed or refractory CD19-positive B-cell ALL received fludarabine and cyclophosphamide with or without alemtuzumab followed by UCART19. Complete remission or remission with incomplete count recovery occurred in 14 of 21 patients (67%) at day 28; UCART19 expansion was only seen in patients who received alemtuzumab. Cytokine release syndrome occurred in 91% (grade 3-4 in 3 patients), neurotoxicity in 38% (all grade 1-2), and grade 1 skin graft-versus-host disease in two patients. Most responders proceeded to allogeneic transplant, and durability without transplant was limited.
- 21 patients (7 children, 14 adults) with relapsed/refractory B-ALL treated with donor-derived, TALEN-edited CD19 CAR-T cells.
- Complete remission or CRi in 14 of 21 (67%) at day 28.
- CAR-T expansion required alemtuzumab-containing lymphodepletion; no expansion without it.
- CRS 91% (3 grade 3-4); neurotoxicity 38%, all grade 1-2; grade 1 skin GvHD in 2 patients.
- 10 responders proceeded to allogeneic transplant; persistence of UCART19 was short (weeks), limiting durability.
The UCART19 report was the first clinical evidence that a universal, pre-manufactured CAR-T made from a donor can work, avoiding the weeks of autologous manufacturing and the problem of patients whose own T cells are too damaged. It set the template for later allogeneic programmes (including cemacabtagene autoleucel in the ALPHA studies) and for in vivo CAR generation. Short persistence and the need for deep lymphodepletion remain the central weaknesses.
- Very small phase 1 with heterogeneous dosing.
- Remissions were mostly a bridge to transplant; few durable responses without further therapy.
- Alemtuzumab-based lymphodepletion causes profound, prolonged immunosuppression and infection risk.
- Gene editing raises questions about off-target effects and chromosomal rearrangements.