Tandem CD19/20 CAR-T Showed Durable Efficacy in Patients with Relapsed/Refractory B-Cell Lymphoma: Interim Results from a Multicenter Phase I/II Trial

Introduction：CD19 chimeric antigen receptors (CARs) T-cell therapy has shown remarkable effects in patients with relapsed/refractory B-cell lymphoma (r/r-BCL). However, its efficacy is limited due to the loss or downregulation of CD19 antigen. Recent studies have found that simultaneous targeting of two antigens can overcome CD19^- relapse in r/r-BCL. However, the combination of CD19 and CD20 CAR-T has not been fully elucidated. Hence, we designed a series of dual CARs targeting CD19 and CD20, including tandem, loop connections, and parallel style. By comparison, we confirmed the optimized hinge tandem CD19/20 CAR-T was superior to other structures in both in vitro and in vivo experiments. This study aimed to evaluate the safety and efficacy profiles of the novel optimized hinge tandem CD19/20 CAR-T cell therapy in patients with r/r-BCL.

Methods：In a multicenter, open-label single-arm phase I/II trial, we enrolled 44 patients with r/r-BCL (DLBCL, n=33; BL, n=4; FL, n=3; MZL, n=2; MCL=2) since July 2022. These patients came from the hematology department of Tongji Hospital, Shanxi Bethune Hospital, and The Fourth Hospital of Hebei Medical University (NCT05618041, NCT05388695 and NCT04666168). This study was approved by the Ethics Committees of the above three centers, and informed consent was obtained from all patients.

Results：Of the 44 patients who received tandem CD19/20 CAR-T infusion, the median age was 52 years (range, 28-83), 88.6% (39/44) had stage III/ IV disease before enrollment. 68.2% (30/44) had undergone third-line or higher treatment, and 9.1% (4/44) and 15.9% (7/44) patients had undergone autologous stem cell transplantation (ASCT) and CAR-T therapy in the past. Until the cutoff date (July 21st, 2024), the best and three months overall response rate (ORR) was 84.1% (37/44), with 52.3% (23/44) of the patients achieved a complete response (CR) and 31.8% (14/44) had a partial response (PR). The median progression-free survival (PFS) and median overall survival (OS) was not reached with median follow-up of 6.8 months. The estimated one-year PFS and OS for all enrolled patients were 70.6% (95%CI, 52.0-83.1%) and 83.3% (95%CI, 65.5-92.4%), respectively. For patients who achieved ORR at month 3, the estimated one-year PFS and OS were 79.4% (95% CI, 58.5-90.5%) and 92.7% (95%CI, 72.6-98.2%), respectively. For subgroup analysis, the patients who received ASCT followed by CD19/20 CAR-T cell infusion had a higher CR rate than those treated with CD19/20 CAR-T cell alone (CRR, 81.3% vs 35.7%). We found that patients with ASCT followed by CD19/20 CAR-T cell infusion tended to have better estimated one-year PFS (80.2% vs 65.5%) and OS (91.7% vs 78.9%) than those treated with CD19/20 CAR-T cell alone. Grade 1-2 cytokines release syndrome (CRS) affected 54.5% (24/44) patients, while grade 3 CRS affected 2.3% (1/44) patients. No patients experienced grade 4 CRS. Grade 1 ICANS occurred in 4.5% (2/44) patients. The main grade 3-4 adverse events (AEs) were neutropenia (100%), thrombocytopenia (54.4%) and infection (20.5%). However, grade 3-4 AEs were relatively rare in other NCI CTCAE preferred term in this cohort. The peak of CAR-T expanded mainly occurred 7-14 days after CAR-T infusion. The median peak of CAR-T copies was 63272/ug gDNA (95%CI, 24024-117828/ug gDNA) in patients achieving CR versus 4621.1/ug gDNA (95%CI, 2144-48487/ug gDNA) in those not achieving CR (p=0.02).

Conclusions: In summary, our results show that tandem CD19/20 CAR-T for r/r-BCL delivered durable remissions with safe profile.