CAR-T靶向治疗实体瘤！

编者按】12月（6-9）日在美国旧金山召开的第56届美国血液学会年会（ASH）会议上，基因工程T细胞或者说嵌合抗原受体T细胞的研究再次成为代表们热议的话题。因为临床研究证明这种方法能有效治疗白血病和淋巴瘤。这是一种利用基因改造技术表达肿瘤特异性嵌合抗原受体(Chimeric antigen receptor，CAR)的T细胞，研究显示这种细胞具有独特的靶向性、杀伤活性和持久性，是过继性细胞免疫治疗的最新解决方案；理论上，除了白血病和淋巴瘤,这一方法也能成为治疗其他癌症的手段，前提是不能把生存需要的细胞全面清除，这需要在肿瘤细胞特异抗原上有明确的认识。只有这样才能实现将癌细胞全部杀灭，同时保留正常细胞免于被殃及。如果能达到这样的目的，这些研究的先驱们就会写入癌症治疗的历史。

在2014.12.6，5:30 PM-7:30 PM；West Building, Level 1 (Moscone Center)的ASH会议中报道了CAR-T对实体瘤的治疗研究初探，会议题目：“Engineered T Cell Receptor-Mimic Antibody, (TCRm) Chimeric Antigen Receptor (CAR) T Cells Against the Intracellular Protein Wilms Tumor-1 (WT1) for Treatment of Hematologic and Solid Cancers”

报道摘要：

目前表达肿瘤相关嵌合抗原受体的过继T细胞疗法（CAR-T）已在特定的白血病临床应用中取得成功，因而寻找新的肿瘤（血液和恶性实体瘤）靶抗原就成为必须，然而目前大多数CARs仅针对特定类型的细胞表面抗原。该实验设计了第一个针对人胞内蛋白——WT1（肾母细胞瘤蛋白）的CAR-T，WT1在包括急慢性白血病和许多实体瘤中都过度表达。该CAR的T细胞受体是ESK1TCRm的单抗衍生物，称为WT1 28z，在与RMFPNAPYL肽反应时高表达在HLA-A*02:01类细胞表面。用Cr51试验检测其对各种肿瘤细胞系的细胞毒性，包括巨核细胞系SET2，急性髓细胞性白血病(AML)细胞系AML14，多发性骨髓瘤细胞系KARPAS，以及卵巢癌细胞系OVCAR3，并用非相关抗原的CAR-T作对照，试验发现，WT1 28z CAR-T细胞对原发性AML骨髓细胞有细胞毒性，与非相关抗原的CAR-T相比，在和原代细胞或肿瘤细胞系共培养时，WT1 28z CAR-T可增强促炎症细胞因子的分泌，例如IFN-g, IL-2, GM-CSF。WT1 28z T细胞对于WT1-HLA-A*02:01来说是特异性的，并不对HLA-A*02:01和WT1双阴的细胞系或初始细胞产生细胞毒性。目前正在用AML和卵巢癌的小鼠模型分别对WT1 28z T细胞和非相关抗原的CAR-T进行疗效评估，其最终的目标是能够让这种新技术在血液瘤和实体瘤治疗中得到应用。上述研究提示一个假设，即CAR-T或许也可以利用胞内抗原进行定向改造。

 

2155 Engineered T Cell Receptor-Mimic Antibody, (TCRm) Chimeric Antigen Receptor (CAR) T Cells Against the Intracellular Protein Wilms Tumor-1 (WT1) for Treatment of Hematologic and Solid Cancers

Sarwish Rafiq, PhD^1*, Tao Dao, MD/PhD^2*, Cheng Liu, PhD^3*, David A. Scheinberg, MD, PhD⁴ and Renier J Brentjens, MD, PhD⁵

¹Memorial Sloan-Kettering Cancer Center, New York, NY
²Sloan Kettering Institute, New York, NY
³Eureka Therapeutics, Emeryville, CA
⁴Chairman, Molecular Pharmacology and Chemistry, Memorial Sloan Kettering Cancer Center, New York, NY
⁵Leukemia Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY

 

Adoptive transfer therapy of T cells expressing chimeric antigen receptors (CAR) against tumor-associated antigens has been shown to be clinically successful in a limited set of leukemia.  However, novel antigen targets for both hematological and solid malignancies are required.  Most CARs described thus far are targeted against external antigens on particular cell types.  We have designed and engineered the first CAR T cell against a human intracellular protein, WT1.  WT1 is overexpressed in many cancers, including acute and chronic leukemias and numerous solid tumors.   Our TCRm CAR, derived from the ESK1 TCRm mAb, termed WT1 28z, is reactive with the RMFPNAPYL peptide of the WT1 protein that is processed and presented on the surface of cells in the context of HLA-A*02:01.   WT1 28z expressing T cells have high expression of the CAR on their surface.  They are cytotoxic in standard ⁵¹Cr assays against a range of cancer cell lines, including the megakaryoblastic cell line SET2, the acute myeloid leukemia (AML) cell line AML14, the multiple myeloma cell line KARPAS, and the ovarian cancer line, OVCAR3, as compared to CAR T cells against an irrelevant antigen. The WT1 28z CAR T cells are also cytotoxic against primary AML bone marrow blasts in this assay.  When co-cultured with these primary cells or cancer cell lines, the WT1 28z CAR T cells have enhanced production of proinflammatory cytokines such as IFN-g, IL-2, and GM-CSF, as compared to irrelevant CAR T cells.  Importantly, WT1 28z T cells are specific for the WT1-HLA-A*02:01 complex.  The cells do not show cytotoxicity against cell lines or primary cells that are not both HLA-A*02:01- positive and WT1 positive.  WT1 28z T cells are currently being tested alongside irrelevant antigen CAR T cells in AML and ovarian cancer murine models in vivo to assess efficacy, with the ultimate goal of translating this novel approach into the clinical setting for both hematological and solid cancers. The data provide the proof-of-concept that CAR T cells also may be directed at intracellular antigens.