Cellectis advances off-the-shelf cancer therapies on strong trial data

Cellectis (NASDAQ:CLLS) reported highly encouraging clinical updates for its off-the-shelf, gene-edited cancer therapies, highlighting a perfect overall response rate in a target group of leukemia patients.

The New York-based biotechnology firm presented final Phase 1 data for its lead asset, lasme-cel, alongside preliminary data for its lymphoma candidate, eti-cel, at the European Hematology Association (EHA) 2026 Congress.

The findings bolster Cellectis’ standing in the competitive allogeneic—or donor-derived—chimeric antigen receptor T-cell (CAR-T) space, which aims to provide ready-to-use oncology treatments without the manufacturing delays of traditional patient-specific therapies.

In the final readout of the Phase 1 BALLI-01 trial evaluating lasme-cel in relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL), the cell therapy achieved a 100% overall response rate among the seven patients in the target Phase 2 population.

Within this cohort of heavily pretreated patients, 57% achieved either a complete remission or complete remission with incomplete blood count recovery.

Deep clearances of the cancer were notable, with 75% of responders testing negative for minimal residual disease, an indicator that no trace of the leukemia could be detected by sensitive laboratory tests.

Crucially, all responding patients were able to successfully bridge to a subsequent hematopoietic stem cell transplant, which can offer a long-term cure.

The safety profile remained manageable across the wider study population.

Severe side effects typical of CAR-T treatments were uncommon, with grade 3 or higher cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome each occurring in 4% of patients.

Immune effector cell-associated hematotoxicity occurred in 2% of participants, and all observed severe toxicities subsequently resolved.

Cellectis also shared early data from its Phase 1 NATHALI-01 study investigating eti-cel, an experimental asset that simultaneously targets both the CD20 and CD22 proteins on cancer cells to reduce the risk of immune escape.

In the trial's optimal dose cohort for relapsed or refractory B-cell non-Hodgkin lymphoma, eti-cel demonstrated an 88% overall response rate and a 63% complete remission rate.

To further boost treatment efficacy and cell expansion, the company is actively investigating the specific impacts of alemtuzumab exposure during the pre-treatment lymphodepletion process, alongside the use of low-dose interleukin-2 to support the survival of the engineered cells.

Both the pivotal Phase 2 trial for lasme-cel and the Phase 1 study for eti-cel are actively recruiting new patients.

Cellectis indicated that key data analyses for both oncology programs are on track to be disclosed in the fourth quarter of 2026.