Cancer Immunology Discovery, Oncology Research and Development, Worldwide Research and Development, Pfizer Inc., South San Francisco, California, United States of America.
Discovery Sciences, Medicinal Sciences, Worldwide Research and Development, Pfizer Inc., Groton, Connecticut, United States of America.
PLoS One. 2018 Mar 19;13(3):e0194688. doi: 10.1371/journal.pone.0194688. eCollection 2018.
The development of therapeutic monoclonal antibodies through mouse immunization often originates drug candidates that are not cross-reactive to the mouse ortholog. In such cases, and particularly in oncology, drug efficacy studies are performed on human tumor xenografts or with "surrogate" anti-mouse ortholog antibodies if targeting tumor host cells. Safety assessment of drug candidate(s) is performed at a later development stage in healthy non-human primates. While the latter remains necessary before a drug advances into human subjects, it precludes evaluation of safety in disease conditions and drug de-risking during early development. Therefore, mouse models that allow concomitant evaluation of drug efficacy and safety are highly desirable. The C-X-C motif chemokine receptor 4 (CXCR4) is an attractive target for tumor-targeted and immuno-oncology therapeutics, with multiple mouse immunization-derived antibodies undergoing clinical trials. Given the pleiotropic role of CXCR4 in cancer biology, we anticipate continuous interest in this target, particularly in the testing of therapeutic combinations for immuno-oncology. Here, we describe the generation and validation of the first mouse knock-in of the whole coding region of human CXCR4. Homozygous human CXCR4 knock-in (hereafter designated as HuCXCR4KI) mice were viable and outwardly healthy, reproduced normally and nursed their young. The expression pattern of human CXCR4 in this model was similar to that of CXCR4 expression in normal human tissues. The human CXCR4 knock-in gene was expressed as a biologically active protein, thereby allowing normal animal development and adequate"homing" of leukocytes to the bone marrow. To further validate our model, we used an in vivo functional assay of leukocyte mobilization from bone marrow to peripheral blood by blocking CXCR4 signaling. Both an anti-human CXCR4 -specific blocking antibody and the small molecule CXCR4 inhibitor AMD3100 induced increased leukocyte counts in peripheral blood, whereas an anti-mouse CXCR4 -specific blocking antibody had no effect. This new mouse model is useful to evaluate efficacy and safety of anti-human CXCR4 -specific drugs as single agents or in combination therapies, particularly in the oncology, immuno-oncology, wound healing and chronic inflammation therapeutic areas.
通过小鼠免疫产生治疗性单克隆抗体的方法通常会产生与小鼠同源物无交叉反应的药物候选物。在这种情况下，特别是在肿瘤学中，如果靶向肿瘤宿主细胞，则在人肿瘤异种移植物或使用“替代”抗小鼠同源物抗体上进行药物功效研究。在健康的非人类灵长类动物中，在后期开发阶段进行候选药物的安全性评估。虽然在药物进入人体受试者之前，后者仍然是必要的，但它排除了在疾病情况下评估安全性和在早期开发中降低药物风险。因此，同时评估药物功效和安全性的小鼠模型是非常需要的。C-X-C 基序趋化因子受体 4 (CXCR4) 是肿瘤靶向和免疫肿瘤治疗的有吸引力的靶标，有多种通过小鼠免疫产生的抗体正在进行临床试验。鉴于 CXCR4 在癌症生物学中的多效性作用，我们预计对该靶标会持续关注，特别是在免疫肿瘤学中测试治疗组合。在这里，我们描述了人类 CXCR4 全长编码区的第一个小鼠基因敲入的产生和验证。杂合人 CXCR4 基因敲入（此后指定为 HuCXCR4KI）小鼠具有活力且外观健康，正常繁殖并哺乳其幼崽。该模型中人 CXCR4 的表达模式与正常人类组织中 CXCR4 的表达相似。该人 CXCR4 敲入基因表达为具有生物活性的蛋白质，从而允许正常的动物发育和白细胞充分“归巢”到骨髓。为了进一步验证我们的模型，我们使用了一种体内功能性测定法，通过阻断 CXCR4 信号来测定白细胞从骨髓向外周血的动员。抗人 CXCR4 特异性阻断抗体和小分子 CXCR4 抑制剂 AMD3100 都诱导外周血中白细胞计数增加，而抗小鼠 CXCR4 特异性阻断抗体则没有效果。这种新的小鼠模型可用于评估抗人 CXCR4 特异性药物作为单一药物或联合疗法的功效和安全性，特别是在肿瘤学、免疫肿瘤学、伤口愈合和慢性炎症治疗领域。
