Here, we examined the role of EP-100 [luteinizing hormone-releasing hormone (LHRH) ligand joined to a lytic peptide], improving the efficacy of immune checkpoint blockade. LHRH-R–positive murine ovarian cancer cells (ID8, IG10, IF5, and 2C12) were sensitive to EP-100 and were specifically killed at low micromolar levels through LHRH-R. EP-100 increased PD-L1 levels on murine ovarian cancer cells. In vivo syngeneic mouse models (ID8 and IG10) demonstrated that single-agent EP-100 reduced tumor volume, tumor weight, and ascites volume. The greatest reductions in tumor and ascites volume were observed with the combination of EP-100 with an anti–PD-L1 antibody. Immune profiling analysis showed that the population of CD8+ T cells, natural killer cells, dendritic cells, and macrophages were significantly increased in tumor and ascitic fluid samples treated with anti–PD-L1, EP-100, and the combination. However, monocytic myeloid suppressor cells, B cells, and regulatory T cells were decreased in tumors treated with anti–PD-L1, EP-100, or the combination. In vitro cytokine arrays revealed that EP-100 induced IL1α, IL33, CCL20, VEGF, and Low-density lipoprotein receptor (LDLR) secretion. Of these, we validated increasing IL33 levels following EP-100 treatment in vitro and in vivo; we determined the specific biological role of CD8+ T-cell activation with IL33 gene silencing using siRNA and Cas9-CRISPR approaches. In addition, we found that CD8+ T cells expressed very low level of LHRH-R and were not affected by EP-100. Taken together, EP-100 treatment had a substantial antitumor efficacy, particularly in combination with an anti–PD-L1 antibody. These results warrant further clinical development of this combination.

中文翻译：

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LHRH-R靶向裂解肽在卵巢癌中的增强免疫治疗

在这里，我们检查了 EP-100 [与裂解肽结合的促黄体激素释放激素 (LHRH) 配体] 的作用，提高了免疫检查点阻断的功效。LHRH-R 阳性小鼠卵巢癌细胞（ID8、IG10、IF5 和 2C12）对 EP-100 敏感，并通过 LHRH-R 在低微摩尔水平下被特异性杀死。EP-100 增加了小鼠卵巢癌细胞的 PD-L1 水平。体内同基因小鼠模型（ID8 和 IG10）表明，单剂 EP-100 可减少肿瘤体积、肿瘤重量和腹水体积。EP-100 与抗 PD-L1 抗体的组合观察到肿瘤和腹水体积的最大减少。免疫谱分析表明，CD8+ T 细胞、自然杀伤细胞、树突细胞、在用抗 PD-L1、EP-100 及其组合处理的肿瘤和腹水样本中，巨噬细胞和巨噬细胞显着增加。然而，在用抗 PD-L1、EP-100 或其组合治疗的肿瘤中，单核细胞骨髓抑制细胞、B 细胞和调节性 T 细胞减少。体外细胞因子阵列显示 EP-100 诱导 IL1α、IL33、CCL20、VEGF 和低密度脂蛋白受体 (LDLR) 分泌。其中，我们在体外和体内验证了 EP-100 治疗后 IL33 水平的增加；我们使用 siRNA 和 Cas9-CRISPR 方法确定了 CD8+ T 细胞激活与 IL33 基因沉默的特定生物学作用。此外，我们发现 CD8+ T 细胞表达的 LHRH-R 水平非常低，并且不受 EP-100 的影响。总之，EP-100 治疗具有显着的抗肿瘤功效，特别是与抗 PD-L1 抗体联合使用。这些结果保证了这种组合的进一步临床开发。