Updated Follow-up of a Phase 1 Trial of Bispecific CART19/20 Cells for Relapsed or Refractory Non-Hodgkin Lymphoma

Abstract

CART19/20 was developed by engineering autologous naïve/memory T (T N/MEM) cells with a bispecific anti-CD19/CD20 chimeric antigen receptor (CAR) with the goal of mitigating antigen escape and lack of CAR T-cell persistence. We report an update of an ongoing first-in-human phase 1 clinical trial of CART19/20 for patients with relapsed/refractory non-Hodgkin lymphoma (R/R NHL) (NCT04007029). Eligible patients were ≥18 years old with R/R diffuse large B-cell lymphoma (DLBCL) or primary mediastinal B-cell lymphoma (PMBCL) after ≥2 prior lines of therapy, or with mantle-cell lymphoma (MCL), follicular lymphoma (FL), or CLL/SLL after ≥3 prior lines of therapy. Autologous leukocytes were obtained by leukapheresis and sorted for CD14-/CD25-/CD62L+ T N/MEM cells, followed by lentiviral transduction of the bispecific CD19/CD20 CAR. Lymphodepletion chemotherapy with fludarabine 30 mg/m 2/day and cyclophosphamide 500 mg/m 2/day was administered on Days −5 to −3 prior to CAR T-cell infusion. The primary endpoint was assessment of safety. Secondary endpoints were overall response rate (ORR), progression free survival (PFS), overall survival (OS), and CART19/20 transgene persistence. As of data cutoff on July 21, 2023, 11 patients had received CART19/20 cells (6 DLBCL, including 4 transformed FL; 3 primary FL; 1 PMBCL; 1 MCL). Patients were treated at two dose levels, either 50 x 10 6 ± 30% CAR+ cells (8 patients) or 200 x 10 6 ± 30% CAR+ cells (3 patients). The median age was 58 (range: 34 to 70). Patients had received a median of 3 prior lines of therapy (range: 2 - 4). None of the treated patients had received prior CAR-T cell therapy; one patient had received a prior CD19-directed therapy. All patients had stage IV disease and 9 of 11 patients received bridging therapy. The engineered CART19/20 cells were enriched with central-memory T cells (T CM: CD45RA-/CD45RO+/CD62L+) which composed a median of 30.8% (range: 5.3 - 80.1%) of the CAR+ T-cells in the infused products. There were no occurrences of CRS grade ≥ 2 or neurotoxicity of any grade. Six patients had grade 1 cytokine release syndrome (CRS) with a median onset of 8 days from infusion (range: 5 - 11 days). One patient met criteria for dose-limiting toxicity with persistent thrombocytopenia after Day+120. Ten of the 11 patients achieved an objective response (91% ORR), with 8 patients (73%) achieving complete response (CR). One patient with FL, who progressed 18 months after receiving CART19/20, received a second infusion of CART19/20 cells and achieved a second CR for 14.9 months. With a median follow-up of 32.3 months (range: 5.1 - 44.0 months), the median PFS (95% CI 2.6 months - not estimable) and median OS (95% CI 5.7 months - not estimable) have not been reached. Overall, CART19/20 demonstrated a favorable safety profile with no severe CRS or neurotoxicity of any grade. Moreover, CART19/20 showed robust activity in patients with R/R NHL with durable responses seen. By utilizing a bispecific CAR and enriching for T N/MEM cells, this phase 1 trial of CART19/20 demonstrates the possibility of improving outcomes through targeting common mechanisms of CAR-T cell resistance.