Background: Although programmed death-1 (PD-1) blockade is effective in treating several types of cancer, the efficacy of this agent in glioblastoma (GBM) is largely unknown. Methods: We evaluated therapeutic effects of anti-PD-1, temozolomide (TMZ), and their combination in an orthotopic murine GBM model. The phenotype, number, and composition of lymphocytes were evaluated using flow cytometry. Transcriptional profiles of tumor tissues were analyzed using microarrays. Generation of antitumor immunological memory was investigated upon rechallenge. Results: Combined treatment with anti-PD-1 and TMZ yielded synergistic antitumor efficacy in the presence of donor-originated PD-1+CD8+ T cells in vitro, necessitating in vivo validation. Whereas TMZ did not rescue GBM-implanted mice, anti-PD-1 completely eradicated GBM in 44.4% of mice, and combination of anti-PD-1 and TMZ in all mice. Anti-PD-1 significantly increased the number of tumor-infiltrating lymhpocytes (TILs), and reduced frequencies of exhausted T cells and regulatory T cells. However, combining TMZ with anti-PD-1 significantly decreased the number of TILs, which was also observed with TMZ treatment alone. A transcriptome analysis of tumor tissues revealed that anti-PD-1 monotherapy perturbed immune-related genes, distinctly with combined therapy. Upon rechallenge, tumor growth was not observed in mice cured by anti-PD-1 monotherapy, whereas tumors regrew in the combination group. Furthermore, an analysis of peripheral blood revealed that antitumor memory T cells were generated in mice cured by anti-PD-1 monotherapy, not in the combination group. Conclusion: PD-1 blockade induces long-term therapeutic response, and combination with TMZ further enhances antitumor efficacy. However, immunological memory is provoked by anti-PD-1 monotherapy, not by combined therapy.

中文翻译：

---

抗PD-1和替莫唑胺联用治疗成胶质细胞瘤的效果。

背景：尽管程序性死亡1（PD-1）阻断剂可有效治疗多种类型的癌症，但该药物在胶质母细胞瘤（GBM）中的功效尚不清楚。方法：我们评估了抗PD-1，替莫唑胺（TMZ）及其组合在原位鼠GBM模型中的治疗效果。使用流式细胞仪评估淋巴细胞的表型，数量和组成。使用微阵列分析肿瘤组织的转录谱。再挑战后研究了抗肿瘤免疫记忆的产生。结果：在体外存在供体来源的PD-1 + CD8 + T细胞的情况下，抗PD-1和TMZ的联合治疗产生协同的抗肿瘤功效，需要进行体内验证。TMZ不能挽救植入GBM的小鼠，而抗PD-1完全消除了44.4％的小鼠中的GBM，并在所有小鼠中联合使用抗PD-1和TMZ。抗PD-1可显着增加肿瘤浸润淋巴细胞（TIL）的数量，并减少精疲力竭的T细胞和调节性T细胞的频率。但是，将TMZ与抗PD-1组合使用可显着降低TIL的数量，这也可通过单独的TMZ治疗观察到。肿瘤组织的转录组分析显示，抗PD-1单药疗法与联合疗法明显干扰了免疫相关基因。再挑战后，在抗PD-1单一疗法治愈的小鼠中未观察到肿瘤生长，而在组合组中肿瘤复发。此外，对外周血的分析显示，抗肿瘤记忆T细胞在通过抗PD-1单一疗法治愈的小鼠中产生，而不是在联合组中。结论：PD-1阻断可引起长期治疗反应，与TMZ组合可进一步增强抗肿瘤功效。但是，免疫记忆是通过抗PD-1单一疗法而非组合疗法引起的。