Center for Cell Engineering, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Cancer Res. 2011 Apr 15;71(8):2871-81. doi: 10.1158/0008-5472.CAN-10-0552. Epub 2011 Apr 12.
Human T cells genetically modified to express chimeric antigen receptors (CAR) specific to the B cell tumor antigen CD19 can successfully eradicate systemic human CD19(+) tumors in immunocompromised SCID (severe combined immunodeficient)-Beige mice. However, in the clinical setting, CD4(+) CD25(hi) T regulatory cells (Treg) present within the tumor microenvironment may be potent suppressors of tumor-targeted effector T cells. In order to assess the impact of Tregs on CAR-modified T cells in the SCID-Beige xenotransplant model, we isolated, genetically targeted and expanded natural T regulatory cells (nTreg). In vitro nTregs modified to express CD19-targeted CARs efficiently inhibited the proliferation of activated human T cells, as well as the capacity of CD19-targeted 19-28z(+) effector T cells to lyse CD19(+) Raji tumor cells. Intravenous infusion of CD19-targeted nTregs into SCID-Beige mice with systemic Raji tumors traffic to sites of tumor and recapitulate a clinically relevant hostile tumor microenvironment. Antitumor efficacy of subsequently infused 19-28z(+) effector T cells was fully abrogated as assessed by long-term survival of treated mice. Optimal suppression by genetically targeted nTregs was dependent on nTreg to effector T-cell ratios and in vivo nTreg activation. Prior infusion of cyclophosphamide in the setting of this nTreg-mediated hostile microenvironment was able to restore the antitumor activity of subsequently infused 19-28z(+) effector T cells through the eradication of tumor-targeted nTregs. These findings have significant implications for the design of future clinical trials utilizing CAR-based adoptive T-cell therapies of cancer.
经基因修饰表达嵌合抗原受体（CAR）、特异性识别 B 细胞肿瘤抗原 CD19 的人 T 细胞可成功消除免疫缺陷 SCID（严重联合免疫缺陷）-Beige 小鼠体内的全身性人 CD19(+)肿瘤。然而，在临床环境中，肿瘤微环境中存在的 CD4(+) CD25(hi) T 调节细胞（Treg）可能是肿瘤靶向效应 T 细胞的有效抑制剂。为了评估 Treg 对 SCID-Beige 异种移植模型中 CAR 修饰 T 细胞的影响，我们分离、基因靶向并扩增了天然 T 调节细胞（nTreg）。体外修饰表达 CD19 靶向 CAR 的 nTreg 可有效抑制活化的人 T 细胞增殖，以及 CD19 靶向 19-28z(+)效应 T 细胞裂解 CD19(+) Raji 肿瘤细胞的能力。静脉输注 CD19 靶向 nTreg 至有全身 Raji 肿瘤的 SCID-Beige 小鼠中，可使 nTreg 归巢至肿瘤部位，并重现临床上具有挑战性的肿瘤微环境。随后输注的 19-28z(+)效应 T 细胞的抗肿瘤疗效完全被阻断，这可通过治疗小鼠的长期存活来评估。基因靶向 nTreg 的最佳抑制作用依赖于 nTreg 与效应 T 细胞的比例以及体内 nTreg 的激活。在这种 nTreg 介导的恶劣微环境中预先输注环磷酰胺能够通过消除肿瘤靶向 nTreg 来恢复随后输注的 19-28z(+)效应 T 细胞的抗肿瘤活性。这些发现对设计未来利用 CAR 为基础的过继性 T 细胞疗法治疗癌症的临床试验具有重要意义。
