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218 Naturally Selected CD7-Targeted Chimeric Antigen Receptor (CAR)-T Cell Therapy for Refractory/Relapsed Acute Myeloid Leukemia: Phase I Clinical Trial

Program: Oral and Poster Abstracts
Type: Oral
Session: 704. Cellular Immunotherapies: Early Phase and Investigational Therapies: Expanding Disease Targets for CAR-T Cell Therapies
Hematology Disease Topics & Pathways:
Research, clinical trials, Acute Myeloid Malignancies, AML, Clinical Research, Diseases, Therapies, Myeloid Malignancies
Saturday, December 9, 2023: 2:15 PM

Xian Zhang, MD1,2*, Junfang Yang2,3*, Jingjing Li2,3*, Liyuan Qiu3*, Hongxing Liu Sr., MD2, Min Xiong3*, Jianqiang Li, PhD4* and Peihua Lu, MD1,5*

1Department of Hematology, Hebei Yanda Lu Daopei Hospital, Langfang, China
2Beijing Lu Daopei Institute of Hematology, Beijing, China
3Hebei Yanda Lu Daopei Hospital, Langfang, China
4Hebei Senlang Biotechnology Co., Ltd., Shijiazhuang, China
5Beijing Lu Daopei Institute of Hematology, Langfang, China


Refractory or relapsed (r/r) acute myeloid leukemia (AML) is associated with a relatively poor prognosis, even in patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT), emphasizing the critical need for novel therapies. Approximately 30% of AML patients express CD7 on their leukemic blasts and malignant progenitor cells. Naturally selected CD7 CAR-T (NS7CAR-T) therapy has shown significant efficacy with a favorable safety profile in T-cell lymphoid malignancies. In a phase I clinical study (https://clinicaltrials.gov NCT04938115), we investigated the safety and efficacy of CAR-T therapy for treating r/r AML patients with CD7-positive disease.


Peripheral blood mononuclear cells were obtained from either the patients themselves (n=9) or the transplant donor (n=1) in cases of relapse post-transplant. T-cells were then purified using CD3+ magnetic beads. The second-generation CD7CAR with a 4-1BB costimulatory domain was manufactured following the manufacturer's protocol. Before the CAR-T cell infusion, bridging therapies were permitted for patients with rapid disease progression. All patients received intravenous fludarabine (30mg/m2/d) and cyclophosphamide (300mg/m2/d) lymphodepletion chemotherapy for three consecutive days (Day -5 to Day -3). The median time from leukapheresis to CAR-T cell infusion was 15 days.


Between June 2021 and January 2023, we enrolled 10 patients with CD7-positive r/r AML (CD7 expression >50% with good intensity) and administered NS7CAR-T cell infusions, with 4 receiving a low dose (5×105/kg) and 6 receiving a medium dose (1×106/kg). Table 1 displays the characteristics of the enrolled patients, revealing a median age of 34 years (7-63 years) and median bone marrow (BM) blasts percentage by flow cytometry (FCM) of 17.0% (2.0-72.7%) at enrollment. One patient presented with diffuse extramedullary disease (EMD). Before enrollment, patients had undergone a median of 9 (range: 3-17) prior lines of therapy. Seven patients had a history of allo-HSCT and the median interval period from the prior transplant to relapse was 12.5 months (3.5-19.5 months). Following infusion, the median peak of circulating NS7CAR-T cells was 2.72×105 copies/μg (0.671~5.41×105 copies/μg) genomic DNA, which occurred around Day 21 (Day 14 - Day 21) based on q-PCR, with 64.68% (40.08%~92.02%) occurring on Day 17 (Day 11 - Day 21) according to FCM. The median transduction efficiency of the products was 95.6% (70.4%-98.5%).

At four weeks post NS7CAR-T cell infusion, 7/10 (70%) patients achieved complete remission (CR) in BM, and 6 of them attained minimal residual disease (MRD)-negative CR. Three patients showed no remission (NR), including 1 with EMD who had partial remission (PR) based on PET-CT evaluation on Day 35. All NR patients were found lost CD7. The median observation time was 178 days (28-752 days). Among the 7 patients who achieved CR, 3 who relapsed from prior transplants underwent consolidative 2nd allo-HSCT about 2 months after CD7 CAR T-cell infusion. Two patients remained in leukemia-free survival on day 752 and day 315, respectively, while 1 patient died on day 241 due to transplant-related mortality. Among the other 4 patients without consolidative allo-HSCT, 3 relapsed on day 47, day 83, and day 115, respectively (all 3 patients were found to have CD7 loss), and 1 patient died from lung infection.

Post-infusion, the majority of patients (80%) experienced mild cytokine release syndrome (CRS), with 7 displaying grade I and 1 having grade II CRS, while 2 patients (20%) experienced grade III CRS. None of the patients had neurotoxicity. Among the 7 patients with prior allo-HSCT, 1 who had a relapse approximately 100 days after prior allo-HSCT developed mild skin graft-versus-host disease following CAR-T therapy.


Our study highlights the NS7CAR-T therapy as a promising approach for achieving a favorable initial CR in CD7-positive AML patients, even in those who have undergone extensive prior treatments and experienced relapse post allo-HSCT. It potentially could serve as a bridging therapy before transplant. CD7 loss is a major issue either in NR patients or relapsed patients. The safety profile of NS7CAR-T therapy was manageable. However, to comprehensively assess the efficacy of NS7CAR-T in treating CD7-positive AML, further data from a larger cohort of patients and longer follow-up time are essential.

Disclosures: No relevant conflicts of interest to declare.

*signifies non-member of ASH