Dual CD19/CD22-Targeting CAR-T Cells for Richter Transformation: A Case Series

Introduction

Patients with Richter's transformation (RT) of chronic lymphocytic leukemia (CLL) to diffuse large B cell lymphoma (DLBCL) show poor prognosis despite complex chemotherapy and hematopoietic cell transplantation (HCT). Targeted agents, bispecific antibodies and CAR-T cells have successfully entered the therapeutic landscape of B-cell malignancies but yet have no established role in the treatment of RT. Here, we report successful longterm complete remission after treatment with academically manufactured dual CD19/CD22 CAR T cells in two patients showing RT relapse after allogeneic HCT. We hypothesize that patients with aggressive RT may be more efficiently treated with academically produced CD19/CD22 CAR T cells that target more than one B cell antigen and thus can reduce antigen escape and the risk of therapy resistance.

Methods

Two patients were treated at the University Hospital Tübingen between February and December 2023. The treatment was approved by the local Cellular Therapy Board and conducted after informed consent. CD19/CD22 targeting CAR-T cells were manufactured in a 12 day production process as previously reported in our academic Good Manufacturing Practice (GMP) laboratory using autologous mononuclear cells, transduced with a human anti-CD19/anti-CD22 lentiviral construct (Miltenyi Biotec) and amplified using the CliniMACS Prodigy platform (Phely et al. JAMA Onc 2024). CAR T cells were applied following lymphodepletion with fludarabine and cyclophosphamide and in vivo expansion was monitored by flow cytometry.

Results

Patient 1 (64 years, male) and Patient 2 (42 years, male) both experienced DLBCL-RT two years post-CLL diagnosis. Both received chemotherapies, rituximab, ibrutinib and HCT and suffered from multiple relapses. Patient 1 relapsed for a second time after HCT in 2023 with severe meningeal involvement, treated with steroids, local therapy and pirtobrutinib before receiving CAR T cells in December 2023. Patient 2, diagnosed with CLL 13 years ago, relapsed with CLL one year after HCT and a few months later he developed DLBCL-RT. Treatment with R-CHOP followed by lenalidomide and rituximab induced complete remission. One year later, a 1^st RT relapse was treated with ibrutinib which induced sustained remission over 7 years. In March 2021 a 2^nd RT-relapse occurred and was treated with rituximab, polatuzumab and bendamustine. After several months of apparent complete remission, the patient relapsed for the 3^rd time. He was bridged with the prior regimen and radiotherapy, before receiving treatment with CAR-T cells in March 2023.

Both patients tolerated the treatment well and remain in complete remission at 17 and 7 months post-infusion. No severe infections occurred. Patient 1 experienced grade I cytokine release syndrome (CRS), treated with tocilizumab, and showed rapid CAR T cell expansion. Patient 2 had grade I CRS and plexus neuritis, also treated with tocilizumab and dexamethasone, with moderate CAR T cell expansion. Patient 2 was later diagnosed with anal carcinoma, treated surgically.

Discussion

Both patients had aggressive RT, characterized by high LDH, low platelet counts, large tumors, and refractoriness to multiple treatments. RT occurs in about 2% of CLL patients, with poor responses to chemotherapy and a median survival of ten months. BTK inhibitors provide some benefit but are often short-lived, highlighting the need for new therapies. Anti-CD19 CAR-T therapy shows promise, though relapses often involve CD19 loss, leading to a short progression free survival, necessitating strategies like dual-targeting CAR-T cells.

Dual-targeting CAR-T therapy, which targets both CD19 and CD22, can prevent antigen escape, enhancing treatment efficacy. This strategy has shown promise in other B-cell malignancies (Nguyen et al. Cancer Med 2023). On-site GMP production enables rapid and fresh CAR-T cell availability without cryopreservation or shipping delays.

This report is the first to discuss dual-targeting CAR-T therapy in RT, with promising outcomes despite a small sample size and short follow-up. These initial findings support further clinical trials to validate the efficacy and safety of this approach in RT patients.

Acknowledgement

WB and CL are equally shared last authors.

No relevant conflicts of interest to declare.