DataSheet_1_Induction of Therapeutic Protection in an HPV16-Associated Mouse Tumor Model Through Targeting the Human Papillomavirus-16 E5 Protein to Dendritic Cells.pdf

HPV E5 is an oncoprotein mainly expressed in premalignant lesions, which makes it an important target for a vaccine to prevent or cure cervical cancer (CC). In this study, we evaluated whether E5 targeted to DEC-205, present in dendritic cells (DCs), could induce a therapeutic protection against HPV16-induced tumor cells in a mouse model. The HPV-16 E5 (16E5) protein was cross-linked to a monoclonal antibody (mAb) specific to mouse DEC-205 (anti-DEC-205:16E5) or to an isotype control mAb (isotype:16E5). Rotavirus VP6 was cross-linked to the mouse anti-DEC-205 mAb (anti-DEC-205:VP6) as a non-specific antigen control. BALB/c mice were inoculated subcutaneously (s.c.) with the 16E5-expressing BMK-16/myc tumor cells, and 7 and 14 days later the mice were immunized s.c. with the conjugates, free 16E5 or PBS in the presence of adjuvant. Tumor growth was monitored to evaluate protection. A strong protective immune response against the tumor cells was induced when the mice were inoculated with the anti-DEC-205:16E5 conjugate, since 70% of the mice controlled the tumor growth and survived, whereas the remaining 30% developed tumors and died by day 72. In contrast, 100% of the mice in the control groups died by day 30. The anti-DEC-205:16E5 conjugate was found to induce 16E5-specific memory T cells, with a Th1/Th17 profile. Both CD4+ and CD8+ T cells contributed to the observed protection. Finally, treating mice that had developed tumors with an anti-PD-1 mAb, delayed the tumor growth for more than 20 days. These results show that targeting 16E5 to DEC-205, alone or combined with an immune checkpoint blockade, could be a promising protocol for the treatment of the early stages of HPV-associated cancer.

人乳头瘤病毒（HPV）E5是主要表达于癌前病变中的癌蛋白，因此成为预防或治愈宫颈癌（CC）的关键疫苗靶点。本研究旨在评估靶向树突状细胞（dendritic cells, DCs）表面DEC-205的E5抗原，能否在小鼠模型中诱导抗HPV16诱导肿瘤细胞的治疗性保护效应。
本研究将HPV-16 E5（16E5）蛋白分别与针对小鼠DEC-205的单克隆抗体（monoclonal antibody, mAb）交联，制备anti-DEC-205:16E5复合物；同时以同型对照单克隆抗体交联制备isotype:16E5复合物作为对照。此外，将轮状病毒VP6与小鼠抗DEC-205单克隆抗体交联，制备anti-DEC-205:VP6复合物，作为非特异性抗原对照。
将表达16E5的BMK-16/myc肿瘤细胞皮下（s.c.）接种至BALB/c小鼠体内，于接种后第7天和第14天，分别使用上述交联复合物、游离16E5或磷酸盐缓冲液（PBS）联合佐剂进行皮下免疫。通过监测肿瘤生长情况评估免疫保护效果。
结果显示，经anti-DEC-205:16E5复合物免疫的小鼠可诱导强烈的抗肿瘤保护性免疫应答：70%的小鼠可抑制肿瘤生长并存活，而剩余30%的小鼠则出现肿瘤并于第72天左右死亡。与之形成显著对比的是，所有对照组小鼠均于第30天全部死亡。
进一步研究表明，anti-DEC-205:16E5复合物可诱导产生16E5特异性记忆性T细胞，其细胞因子谱呈现Th1/Th17型；CD4+ T细胞与CD8+ T细胞均参与了本次实验观察到的保护性免疫应答。最后，使用抗PD-1单克隆抗体治疗已成瘤的小鼠，可将肿瘤生长延迟超过20天。
本研究结果证实，单独将16E5靶向至DEC-205，或联合免疫检查点阻断疗法，有望成为治疗HPV相关癌症早期阶段的极具潜力的方案。