英国伦敦大学学院Waseem Qasim团队研究了碱基编辑的CAR7 T细胞治疗T细胞急性淋巴细胞白血病复发的疗效与安全性。这一研究成果发表在2023年6月14日出版的《新英格兰医学杂志》上。

由聚集规则间隔短回文重复序列（CRISPR）引导的胞苷脱氨作用可以介导一种核苷酸高度精确地转化为另一种核苷酸，特别是胞嘧啶转化为胸腺嘧啶，而不会在DNA中产生断裂。因此，可以对基因进行碱基编辑并使其失活，而不会诱导易位和其他染色体畸变。这项技术在复发的儿童T细胞白血病患者中的应用正在研究中。

研究组使用碱基编辑来产生通用的、现成的嵌合抗原受体（CAR）T细胞。使用慢病毒转导健康志愿者供体T细胞，以表达对CD7（CAR7）具有特异性的CAR，该蛋白在T细胞急性淋巴细胞白血病（ALL）中表达。然后，研究组使用碱基编辑使编码CD52和CD7受体以及αβ T细胞受体的β链的三个基因失活，以分别逃避淋巴消耗血清疗法、CAR7 T细胞自相残杀和移植物抗宿主病。并研究了这些编辑细胞在三名复发性白血病儿童中的安全性。

第一名患者是一名13岁女孩，她在异基因干细胞移植后复发了T细胞ALL，在输注单剂量碱基编辑CAR7（BE-CAR7）后28天内出现分子缓解。之后她从原来的捐赠者那里接受了强度降低（非清髓）的异基因干细胞移植，免疫重建成功，白血病持续缓解。来自同一库的BE-CAR7细胞在另外两名患者中显示出强大的活性，尽管一名患者出现了致命的真菌并发症，但另一名患者在病情缓解时接受了异基因干细胞移植。严重不良事件包括细胞因子释放综合征、多谱系细胞减少和机会性感染。

这项1期研究的中期结果支持对复发性白血病患者的碱基编辑T细胞进行进一步研究，并表明了免疫疗法相关并发症的预期风险。

附：英文原文

Title: Base-Edited CAR7 T Cells for Relapsed T-Cell Acute Lymphoblastic Leukemia

Author: Robert Chiesa, M.D.,, Christos Georgiadis, Ph.D.,, Farhatullah Syed, Ph.D.,, Hong Zhan, Ph.D.,, Annie Etuk, Ph.D.,, Soragia Athina Gkazi, Ph.D.,, Roland Preece, Ph.D.,, Giorgio Ottaviano, M.D.,, Toni Braybrook, M.Bio.,, Jan Chu, M.Sc.,, Agnieszka Kubat, B.Sc.,, Stuart Adams, Ph.D.,, Rebecca Thomas, Ph.D.,, Kimberly Gilmour, Ph.D.,, David O’Connor, M.B., Ch.B.,, Ajay Vora, M.B., B.S.,, and Waseem Qasim, M.B., B.S., Ph.D.

Issue&Volume: 2023-06-14

Abstract:

Background

Cytidine deamination that is guided by clustered regularly interspaced short palindromic repeats (CRISPR) can mediate a highly precise conversion of one nucleotide into another — specifically, cytosine to thymine — without generating breaks in DNA. Thus, genes can be base-edited and rendered inactive without inducing translocations and other chromosomal aberrations. The use of this technique in patients with relapsed childhood T-cell leukemia is being investigated.

Methods

We used base editing to generate universal, off-the-shelf chimeric antigen receptor (CAR) T cells. Healthy volunteer donor T cells were transduced with the use of a lentivirus to express a CAR with specificity for CD7 (CAR7), a protein that is expressed in T-cell acute lymphoblastic leukemia (ALL). We then used base editing to inactivate three genes encoding CD52 and CD7 receptors and the β chain of the αβ T-cell receptor to evade lymphodepleting serotherapy, CAR7 T-cell fratricide, and graft-versus-host disease, respectively. We investigated the safety of these edited cells in three children with relapsed leukemia.

Results

The first patient, a 13-year-old girl who had relapsed T-cell ALL after allogeneic stem-cell transplantation, had molecular remission within 28 days after infusion of a single dose of base-edited CAR7 (BE-CAR7). She then received a reduced-intensity (nonmyeloablative) allogeneic stem-cell transplant from her original donor, with successful immunologic reconstitution and ongoing leukemic remission. BE-CAR7 cells from the same bank showed potent activity in two other patients, and although fatal fungal complications developed in one patient, the other patient underwent allogeneic stem-cell transplantation while in remission. Serious adverse events included cytokine release syndrome, multilineage cytopenia, and opportunistic infections.

Conclusions

The interim results of this phase 1 study support further investigation of base-edited T cells for patients with relapsed leukemia and indicate the anticipated risks of immunotherapy-related complications.

DOI: 10.1056/NEJMoa2300709

Source: https://www.nejm.org/doi/full/10.1056/NEJMoa2300709