肿瘤细胞治疗研究
英文原题：Preclinical evaluation of antitumor activity and toxicity of TROP2-specific CAR-T cells for treatment of triple-negative breast cancer.
这些数据表明，尽管靶向 TROP2 的 CAR-T 疗法对 TNBC 细胞系和 PDX 具有强效抗肿瘤活性，但由于 TROP2 在肺等重要器官中表达，其潜在副作用可能是致命的。
背景：三阴性乳腺癌（TNBC）是预后最差的乳腺癌亚型之一，原因在于有效靶向疗法有限。CAR-T 细胞疗法治疗血液癌症效果显著，但用于TNBC仍需进一步开发。一项主要障碍是缺少适合的肿瘤特异性靶点。受近期滋养层细胞表面抗原2（TROP2）抗体药物偶联物在TNBC中取得成功的启发，我们开发了特异性靶向TROP2的第二代CAR，并通过体内外模型正式评估其抗肿瘤活性和安全性。 方法：以经临床验证的人源化抗体Sacituzumab为基础构建靶向TROP2的CAR，并通过逆转录病毒载体在原代人T细胞中表达。体外使用多种TNBC细胞系，检测TROP2 CAR-T细胞的肿瘤细胞毒性、细胞因子产生和T细胞增殖。通过NSG小鼠的细胞系来源原位及转移性异种移植模型、患者来源异种移植（PDX）模型评估抗肿瘤疗效。使用TROP2人源化免疫健全小鼠评估TROP2 CAR-T细胞的安全性，并构建靶向B7-H3和TROP2的“与”逻辑门控SynNotch CAR，以降低TROP2 CAR-T细胞对肿瘤外正常组织的靶向毒性。 结果：人源TROP2 CAR-T细胞在体外及原位、转移性和PDX小鼠模型中均显示出强劲的抗肿瘤活性。TROP2人源化免疫健全小鼠接受TROP2 CAR-T治疗后出现致死性靶向肿瘤同时损伤正常组织的毒性，表现为肺组织严重损伤和全身炎症。B7-H3/TROP2“与”逻辑门控SynNotch CAR-T细胞保持相当的抗肿瘤疗效，同时未出现与TROP2 CAR-T细胞相似的明显不良反应。 结论：数据表明，靶向TROP2的CAR-T疗法对TNBC细胞系和PDX具有强效抗肿瘤活性，但由于肺等重要器官表达TROP2，潜在副作用可能致命。使用“与”逻辑门控CAR是克服其体内毒性的可行方案。本研究为未来开发TROP2 CAR-T细胞疗法治疗TNBC奠定了基础。
BACKGROUND: Triple-negative breast cancer (TNBC) represents a subtype of breast cancer with poorest prognosis due to limited effective targeted therapies. Chimeric antigen receptor T cell (CAR-T) therapy has shown remarkable efficacy in treating hematological cancers, but its application in TNBC requires further development. One major obstacle is the lack of suitable tumor-specific target in TNBC. Inspired by recent success of trophoblast cell-surface antigen 2 (TROP2) antibody-drug conjugate in TNBC, we developed a second-generation CAR that specifically targets TROP2 and formally evaluated its antitumor activity and safety profile using in vitro and in vivo models. METHODS: A CAR molecule targeting TROP2 was constructed based on the clinically-validated humanized antibody Sacituzumab and expressed in primary human T cells using a retroviral vector. Tumor cytotoxicity, cytokine production and T-cell proliferation of TROP2 CAR-T cells were tested against multiple TNBC cell lines in vitro. Antitumor efficacy was evaluated using orthotopic and metastatic models of cell line-derived xenograft in NSG mice and in patient-derived xenograft (PDX) model. The safety profile of TROP2 CAR-T cells was assessed using TROP2-humanized immunocompetent mice and an "AND"-logic gated SynNotch CAR targeting B7-H3 and TROP2 was engineered to minimize off-tumor, on-target toxicity of TROP2 CAR-T cells. RESULTS: Human TROP2 CAR-T cells demonstrated robust antitumor activity in vitro and in orthotopic/metastatic/PDX xenograft mouse models. TROP2 CAR-T cells caused lethal on-target, off-tumor toxicity in TROP2-humanized immunocompetent mice, causing severe tissue damage in lungs and systemic inflammation. The B7-H3/TROP2 "AND"-logic gated SynNotch CAR-T cells showed comparable antitumor efficacy without causing apparent adverse effects as in TROP2 CAR-T cells. CONCLUSIONS: These data indicate that while CAR-T therapy targeting TROP2 possesses potent antitumor activity against TNBC cell lines and PDX, its potential side effects could be lethal due to TROP2 expression in vital organs such as the lung. Using an "AND"-logic gated CAR is a viable solution to overcome its in vivo toxicity. Our study lays the groundwork for future development of TROP2 CAR-T cell therapy for TNBC.
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