A Phase 1 clinical trial has revealed promising results for FT596, a novel off-the-shelf cellular immunotherapy, in patients with relapsed or refractory B-cell lymphomas. The study, published in The Lancet, indicates that this CAR-NK cell therapy, derived from induced pluripotent stem cells (iPSCs), is safe and may offer a less toxic and more accessible alternative to traditional CAR-T cell therapies.
The multi-center trial, co-led by researchers at Washington University School of Medicine in St. Louis, involved 86 patients with various types of B-cell lymphomas who had received a median of four prior lines of therapy. The trial's primary objective was to assess the safety and tolerability of escalating doses of FT596, both as a monotherapy and in combination with rituximab.
CAR-NK Cell Therapy: A Novel Approach
Unlike CAR-T cell therapy, which uses a patient's own T cells, FT596 utilizes natural killer (NK) cells derived from healthy donor tissue via induced pluripotent stem cells (iPSCs). This "off-the-shelf" approach eliminates the need for patient-specific manufacturing, potentially reducing costs and improving accessibility. According to Armin Ghobadi, MD, a professor of medicine at WashU Medicine and lead author of the study, this approach addresses key limitations of CAR-T cell therapies, where manufacturing failures or disease progression can prevent patients from accessing treatment.
The FT596 CAR-NK cells are engineered to target cancer cells in two different ways, potentially mitigating tumor resistance. This contrasts with standard CAR-T cell therapy, which typically targets cancer cells through a single mechanism.
Safety and Efficacy
The trial demonstrated that FT596 was well-tolerated, with no dose-limiting toxicities observed with monotherapy and only one with the combination therapy (prolonged grade 4 thrombocytopenia). Cytokine release syndrome (CRS), a common side effect of immunotherapy, was generally low-grade and manageable. Notably, no patients experienced neurotoxicity or graft-versus-host disease.
In terms of efficacy, patients with follicular lymphoma showed the most promising responses, with all patients experiencing at least a partial response and 85% achieving a complete response. The median duration of response in this group was almost 17 months. Among patients with relapsed or progressed disease after standard CAR-T cell therapy who then received FT596 plus rituximab, 45% responded, with 30% achieving complete remission.
Implications for B-Cell Lymphoma Treatment
These findings suggest that FT596 could represent a significant advancement in the treatment of B-cell lymphomas, particularly for patients who have relapsed after CAR-T cell therapy or who are ineligible for autologous CAR-T cell therapy due to manufacturing issues or other factors. The off-the-shelf nature of FT596 also holds the potential to expand access to cellular immunotherapy in community settings where the infrastructure for collecting and processing patient cells may be limited.
"In patients with follicular lymphoma, FT596 has shown comparable efficacy to the three FDA-approved CAR-T cell therapies, but with significantly reduced toxicity," said Ghobadi. He also noted that nearly half of large B-cell lymphoma patients who relapse after CAR-T therapy could achieve another remission with FT596, representing a significant improvement in outcomes for this difficult-to-treat population.
The apparent safety profile of FT596 also makes it an attractive candidate for investigation in solid tumors and autoimmune diseases.
