France-based Cellectis (Euronext Growth: ALCLS; Nasdaq: CLLS) announced that the US FDA has granted Regenerative Medicine Advanced Therapy (RMAT) designation to lasmecabtagene timgedleucel (lasme-cel; UCART22), a CD22-targeting allogeneic chimeric antigen receptor T-cell (CAR-T) therapy, for the treatment of relapsed or refractory B-cell acute lymphoblastic leukemia (r/r B-ALL). The designation is notable because lasme-cel is currently the only allogeneic CAR-T candidate in a pivotal trial for this indication, positioning it as a potential first-in-class approval.
RMAT designation, established under the 21st Century Cures Act, applies to regenerative medicine therapies — including cell and gene therapies — that treat serious conditions and show preliminary clinical evidence of potential over available options. It confers benefits analogous to Breakthrough Therapy designation, including intensive FDA guidance, rolling review eligibility, and priority review upon Biologics License Application (BLA) submission. Lasme-cel has not previously received any other expedited designation.
The Phase I BALLI-01 trial (NCT04150497) provided the clinical basis for the RMAT application. According to data disclosed at Cellectis’ R&D Day in October 2025 and reiterated in the company’s full-year 2025 financial update in March 2026, 22 patients treated with the Cellectis-manufactured Process 2 (P2) formulation achieved an overall response rate (ORR) of 68%. At the recommended Phase II dose (RP2D; n=12), ORR reached 83%. In the nine patients meeting the target pivotal population criteria — transplant-ineligible, third-line or later (3L+), CD22-positive — ORR was 100%, with a complete remission or complete remission with incomplete count recovery (CR/CRi) rate of 56% and approximately 80% of those responders achieving measurable residual disease (MRD) negativity. No p-values were reported for this single-arm Phase I dataset. Final Phase I data were scheduled for oral presentation at the European Hematology Association (EHA) 2026 Congress on June 13, with Nitin Jain, M.D., of MD Anderson Cancer Center presenting; detailed figures from that session were not yet publicly available at the time of this report.
On safety, lasme-cel demonstrated a rate of grade ≥3 cytokine release syndrome (CRS) of 2.5% across 40 dosed patients, with one case of Grade 2 immune effector cell-associated neurotoxicity syndrome (ICANS) and eight related serious adverse events in total. Critically, no cases of graft-versus-host disease (GvHD) were observed — a finding of particular importance for an allogeneic product, where GvHD has historically been a limiting toxicity.