Tumor cells activate the G2/M cell cycle checkpoint in response to ionizing radiation (IR) and effector immune cell-derived granzyme B to facilitate repair and survival. Wee1 kinase inhibition reverses the ability of tumor cells to pause at G2/M. Here, we hypothesized that AZD1775, a small molecule inhibitor of Wee1 kinase, could sensitize tumor cells to IR and T-lymphocyte killing and improve responses to combination IR and programmed death (PD)-axis immune checkpoint blockade (ICB). Multiple models of head and neck carcinoma, lung carcinoma and melanoma were used in vitro and in vivo to explore this hypothesis. AZD1775 reversed G2/M cell cycle checkpoint activation following IR, inducing cell death. Combination IR and AZD1775 induced accumulation of DNA damage in M-phase cells and was rescued with nucleoside supplementation, indicating mitotic catastrophe. Combination treatment enhanced control of syngeneic MOC1 tumors in vivo, and on-target effects of systemic AZD1775 could be localized with targeted IR. Combination treatment enhanced granzyme B-dependent T-lymphocyte killing through reversal of additive G2/M cell cycle block induced by IR and granzyme B. Combination IR and AZ1775-enhanced CD8+ cell-dependent MOC1 tumor growth control and rate of complete rejection of established tumors in the setting of PD-axis ICB. Functional assays demonstrated increased tumor antigen-specific immune responses in sorted T-lymphocytes. The combination of IR and AZD1775 not only lead to enhanced tumor-specific cytotoxicity, it also enhanced susceptibility to T-lymphocyte killing and responses to PD-axis ICB. These data provide the pre-clinical rationale for the combination of these therapies in the clinical trial setting.

中文翻译：

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在通过Wee1激酶抑制进行电离辐射后，增强直接的细胞毒性和对免疫检查点封锁的反应。

肿瘤细胞响应电离辐射（IR）和效应免疫细胞衍生的颗粒酶B激活G2 / M细胞周期检查点，以促进修复和存活。Wee1激酶抑制作用可逆转肿瘤细胞在G2 / M处停顿的能力。在这里，我们假设，Wee1激酶的小分子抑制剂AZD1775可以使肿瘤细胞对IR和T淋巴细胞杀伤敏感，并改善对IR和程序性死亡（PD）轴免疫检查点封锁（ICB）组合的反应。在体外和体内使用了多种头颈癌，肺癌和黑色素瘤模型来探索这一假说。AZD1775逆转IR后的G2 / M细胞周期检查点激活，从而诱导细胞死亡。IR和AZD1775组合可诱导M期细胞中DNA损伤的积累，并通过补充核苷来挽救，表明有丝分裂灾难。联合治疗可增强体内对同源MOC1肿瘤的控制，全身性AZD1775的靶向作用可通过靶向IR进行定位。组合治疗通过逆转IR和颗粒酶B诱导的加性G2 / M细胞周期阻滞，增强了颗粒酶B依赖性T淋巴细胞的杀伤作用。组合IR和AZ1775-增强的CD8 +细胞依赖性MOC1肿瘤生长控制和已建立肿瘤的完全排斥率在PD轴ICB的设置中。功能分析表明，在分选的T淋巴细胞中肿瘤抗原特异性免疫反应增加。IR和AZD1775的组合不仅导致增强的肿瘤特异性细胞毒性，还增强了对T淋巴细胞杀伤的敏感性以及对PD轴ICB的反应。