2024EHA | Professor Huang He: Targeting CD7 Universal CAR-T Therapy Shows Significant Efficacy and Good Safety in Treating R/R CD7+ T-ALL/LBL Patients

**2024EHA | Professor Huang He: Targeting CD7 Universal CAR-T Therapy Shows Significant Efficacy and Good Safety in Treating R/R CD7+ T-ALL/LBL Patients**

The 29th Annual Meeting of the European Hematology Association (EHA) 2024 concluded successfully on June 16, 2024, in Madrid, Spain. As a premier event in the international hematology field, it showcased the latest advancements in foundational and clinical practices.

At this year’s EHA meeting, several studies from Professor Huang He’s team at the First Affiliated Hospital, Zhejiang University School of Medicine were selected. One of these studies, titled “Phase I Study of Targeting CD7 Universal CAR-T Therapy for Relapsed/Refractory CD7+ T-ALL/LBL Patients,” was featured in a poster presentation.

T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) are aggressive malignancies originating from precursor T cells, often affecting the bone marrow (BM), central nervous system (CNS), and mediastinum. Despite multiple lines of chemotherapy or allogeneic hematopoietic stem cell transplantation, some patients progress to a relapsed/refractory stage with poor prognosis, posing a significant clinical challenge. Current CAR-T cell therapies primarily target B-cell hematologic malignancies and multiple myeloma, such as CD19 CAR-T and BCMA CAR-T, while mature targets for T-cell hematologic malignancies are lacking. Preliminary research data indicate that CD7 could be a potential therapeutic target for T-cell hematologic malignancies. Based on this, the team developed a universal CAR-T product targeting CD7, named RD13-02, characterized by CRISPR/Cas9 technology to modify T-cell receptors (TCR) and CD7, creating an innovative “off-the-shelf” CAR-T cell therapy product aimed at truly achieving shelf-ready cell therapy.

The objective of this study was to evaluate the safety and efficacy of RD13-02 in treating R/R T-ALL/LBL. A total of 12 eligible R/R T-ALL/LBL patients (7 ALL, 5 LBL) were enrolled in the study, all exhibiting CD7 antigen expression. Six patients had extramedullary disease; all had blast cells in the bone marrow, with a median proportion of 64% (range: 6% to 89%), indicating high-risk end-stage patients. The patients, aged 3 to 70 years, were enrolled in a “3+3” dose-escalation study. Based on the total dose of RD13-02, they were randomly divided into four dosage groups (DL-1: 0.5×10^8 CAR+T cells; DL1: 2×10^8 CAR+T cells; DL2: 4×10^8 CAR+T cells; DL3: 6×10^8 CAR+T cells). All patients received a standardized lymphodepletion regimen of fludarabine (30mg/m2/day) and cyclophosphamide (500mg/m2/day) for three consecutive days (Day -5 to Day -3) before CAR-T infusion. Preliminary disease assessment was conducted on Day 28. After determining the MTD and RP2D, dose expansion will be carried out.

The study results indicated that no dose-limiting toxicity (DLT), immune effector cell-associated neurotoxicity syndrome (ICANS), or graft-versus-host disease (GVHD) was observed at any dose level. Cytokine release syndrome (CRS) was manageable, mostly mild (G1, n=8; G2, n=2; G3, n=2). Due to the occurrence of Grade 3 CRS in one patient each in the DL2 and DL3 groups, the DL1 dose was set as RP2D, focusing on safety and efficacy. In the initial 28-day evaluation post-infusion, 9 out of 12 patients achieved CR/CRi. By the second month post-infusion, an additional 2 patients achieved CR/CRi, with an ORR of 92%. All patients showed expansion observed through qPCR, with the expansion occurring between Days 6 to 15 and peaking between Days 8 to 27, with a median duration of 33 days (15-79). The study preliminarily confirmed that the anti-CD7 universal CAR-T product RD13-02 is safe and effective for CD7+ R/R T-ALL/LBL. Long-term efficacy needs more patients and extended follow-up for validation. To date, this study has shown the best clinical results for universal CAR-T therapy for R/R T-ALL/LBL, attracting widespread attention from peers both domestically and internationally at this EHA meeting. Additionally, the Bone Marrow Transplantation Center at the First Affiliated Hospital, Zhejiang University School of Medicine is developing multiple targeted CAR-T cell therapy products for various hematologic malignancies, including B-cell, T-cell, and myeloid malignancies.

**Current Clinical Treatment of T-ALL/LBL**

The treatment of T-ALL/LBL remains a significant clinical challenge. Current strategies involve achieving remission with existing frontline therapies followed by sequential allogeneic or autologous hematopoietic stem cell transplantation, with most patients achieving long-term survival. However, some patients face refractory or relapsed disease with poor prognosis. For these patients, clinical studies of new drugs or treatment strategies, such as innovative drugs based on disease targets and pathways, are actively being conducted but have not achieved significant progress. CAR-T cell therapy, with its excellent efficacy and safety, is currently the most promising innovative therapy. It is hoped that with further research, CAR-T cell therapy can bring more survival benefits to T-ALL/LBL patients.

**Challenges and Strategies in CAR-T Cell Therapy**

Cellular immunotherapy has been a milestone in the medical field over the past decade, showing breakthrough efficacy in hematologic malignancies, but it still faces several challenges that need to be addressed.

First, the discovery of new targets. Current mature CAR-T cell therapy products mainly focus on B-cell hematologic malignancies, and new targets are urgently needed for T-cell, myeloid, and solid tumors.

Second, improving efficacy. Existing CAR-T cell therapy for B-cell hematologic malignancies has an efficacy rate of about 50%, and continuous technological improvements are expected to develop more effective cell therapy products for clinical application.

Third, existing CAR-T products are autologous CAR-T, which are costly and have long treatment cycles, necessitating the development of universal CAR-T to improve patient compliance.

The team’s novel cell therapy research, including the study selected for this EHA meeting, addresses these clinical challenges. Additionally, last year, the team published results on “function-enhanced” CAR-T in the journal *Nature*, using PD-1 site-specific integration and non-viral delivery methods to successfully prepare CAR-T cells, significantly enhancing their therapeutic effects.

Furthermore, managing CAR-T cell therapy complications, such as ICANS and CRS, requires in-depth exploration. Progress has been made in understanding the mechanisms of complications, leading to gene functionalization of CAR-T cells and developing “smart” CAR-T products to achieve “efficacy enhancement and toxicity reduction.” Additionally, exploring CAR-T combinations with small molecule targeted drugs and immunotherapeutic drugs could achieve better efficacy. The team recently published in the *New England Journal of Medicine* on the sequential “integrated” regimen of CD7 CAR-T cell therapy and allogeneic hematopoietic stem cell transplantation (HSCT), showing excellent efficacy in relapsed/refractory hematologic malignancies.

**Future Prospects of Cellular Therapy**

It is well known that hematology has always been at the forefront of medical development, including the application of the first small molecule targeted drugs and the first antibodies. The remarkable efficacy of cellular therapy in hematologic diseases has demonstrated its great potential in clinical practice. In the future, it is believed that with the development and commercialization of more novel cellular immunotherapy products, their efficacy will continue to improve, side effects will gradually decrease, and indications will expand.

In the field of hematologic diseases, in addition to traditional chemotherapy, small molecule targeted drugs, antibody drugs, and hematopoietic stem cell transplantation, cellular therapy has improved the clinical treatment landscape of hematologic diseases and holds a significant position. It is anticipated that in the future, the treatment of hematologic diseases may enter a chemotherapy-free era, bringing higher cure rates and better quality of life for patients.

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