靶向PD-L1的膜表面工程化NK细胞抗头颈部鳞状细胞癌的作用及机制研究

PD-1/PD-L1 immune checkpoint inhibition is the most promising antitumor strategy for many tumor types. However, treatment with PD-1/PD-L1 immune checkpoint inhibitors alone is insufficient to cure advanced head and neck squamous cell carcinoma (HNSCC), the overall response rate (ORR) was about 20%. NK cells play an indispensable role in the antitumor immune response induced by PD-1/PD-L1 immune checkpoint inhibitors. We hypothesize that incorporation of PD-L1 binding peptide, DPPA-1, on the surface of NK cells can enhance the homing of NK cells toward tumor sites, increase the targeted killing of NK cells and block immune escape incited by PD-1/PD-L1 signal pathway. In the present study, a system will be developed to produce PD-L1-redirected surface-engineered NK cells (SE-NK-DPPA-1 cells) through a combination of metabolic glycoengineering and bioorthogonal copper-free click chemistry. Moreover, we will demonstrate that SE-NK-DPPA-1 cells can specifically recognize and effectively kill PD-L1+ HNSCC, and convert the poorly inflamed tumor microenvironment to a highly inflamed microenvironment by in vitro and in vivo experiments. In addition, the molecular mechanism that SE-NK-DPPA-1 mediated antitumor activity will be elucidated. This study will provide a potential source of allogeneic SE-NK-DPPA-1 cells, which can offer a promising therapy avenue for advanced HNSCC and has a bright prospect of clinical application.

PD-1/PD-L1免疫检查点阻断治疗是目前最具有前景的肿瘤治疗方法，但其治疗晚期头颈部鳞状细胞癌的总缓解率不足20%。NK细胞在PD-1/PD-L1免疫检查点抑制剂激活的抗肿瘤免疫反应中发挥重要作用。我们假设将特异性结合PD-L1的多肽DPPA-1修饰到NK细胞表面能显著增强NK细胞的靶向肿瘤组织迁移能力及其杀伤活性，并有效阻断PD-1/PD-L1通路介导的免疫逃逸。本课题拟通过代谢糖生物工程和无铜点击化学相结合的方式将DPPA-1多肽偶联到NK细胞表面，制备靶向PD-L1的膜表面工程化NK细胞（SE-NK-DPPA-1细胞），并通过体外、体内实验探究SE-NK-DPPA-1细胞特异性识别、高效杀伤PD-L1+ HNSCC及逆转肿瘤微环境免疫耐受的作用及机制。本研究将制备可同种异体使用的SE-NK-DPPA-1细胞，以期为晚期HNSCC的临床治疗提供新的思路并具有潜在的临床应用前景。

PD-1/PD-L1免疫检查点抑制剂能够激活显著、持久的抗肿瘤免疫反应，已经被批准用于包括晚期HNSCC在内多种肿瘤的治疗，是目前最具有前景的肿瘤治疗手段。但是，对于晚期HNSCC患者，PD-1/PD-L1免疫检查点抑制剂的总缓解率不足20%，因此，探寻如何提高阻断PD-1/PD-L1通路治疗HNSCC的效果具有重要的研究意义，也是目前研究的热点。我们通过代谢糖生物工程和无铜点击化学相结合的方式将DPPA-1多肽偶联到NK细胞表面，制备靶向PD-L1的膜表面工程化NK细胞（SE-NK-DPPA-1细胞），我们发现SE-NK-DPPA-1细胞可以特异性的杀伤PD-L1阳性HNSCC细胞，分泌IFN-γ的能力显著增强。此外，SE-NK-DPPA-1细胞可以阻断PD-1/PD-L1通路，显著地激活NK细胞的Fyn-PLC、Syk-Erk和NF-κB信号通路。我们还发现SE-NK-DPPA-1细胞能够显著地抑制PD-L1阳性HNSCC皮下移植瘤的生长并逆转免疫抑制微环境。本研究通过非病毒转染的方式制备了一种靶向PD-L1 的可同种异体使用、“现货式”的SE-NK-DPPA-1细胞在增强NK细胞肿瘤浸润能力和靶向杀伤活性的同时，能有效阻断PD-1/PD-L1通路介导的免疫逃逸。本项目将为临床治疗晚期HNSCC提供新思路。

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