Efficacy and safety of autologous CD5-KO anti-CD5 CAR-T cells in relapsed/refractory CD5+ hematological malignancies

Chimeric antigen receptor (CAR)-T cell therapy targeting antigens shared with normal T cells requires genetic modifications to prevent fratricide. This phase 1 trial evaluates autologous CD5-targeting CAR-T cells with CD5 gene deletion (CT125A) in seven patients with relapsed/refractory CD5+ hematologic malignancies. The overall response rate is 85.7%, including four complete responses. All patients experience cytokine release syndrome (six grade 1-2, one grade 3), and two patients develop immune effector cell-associated neurotoxicity syndrome. The most common grade ≥3 adverse events are cytopenia and infection, with unique observations of rash and autoimmune-related events. Post-infusion immunophenotyping shows persistent depletion of CD5+ T cells and CD19+ B cells, with reduced CD4/CD8 ratios. The human CD5 knockin murine model reveals skin lesions without significant vital organ involvement. These findings demonstrate CT125A's therapeutic potential in CD5+ malignancies while highlighting the need for safety optimization. The trial has been registered at ClinicalTrials.gov (NCT04767308).