新生抗原neoantigen介导溶瘤病毒治疗复发性卵巢癌的应用及机制研究

After initial surgery and first-line chemotherapy, many ovarian tumor patients have subsequently developed a cancer recurrence. In clinic, recurrent or relapsed ovarian patients have very limited options. Fewer than one in ten such patients survive beyond 5 years following standard salvage chemotherapy. New, non-toxic strategies, capable of systemic targeting and destroying cancers, are needed. Designing individualized neoantigen-based vaccines gives hope for recurrent ovarian cancers. The proposed study is based on the results of previous ex vivo sequencing of tumors in 5 patients with advanced ovarian cancer. Bioinformatics analysis predicts 125 antigen-specific epitopes for these patients. The antigenic peptides will synthesized and screened for tumor specificity in patients with ovarian cancer. The selected antigenic peptides will then be inserted into oncolytic vaccinia virus for expression..Oncolytic virus is engineered virus that preferentially infect and lyse cancer cells. Oncolytic vaccinia virus possess several biologic properties that make it the ideal vaccine vectors, namely large payloads, not incorporated into host genome, and driving high level expression of antigenic peptides. This individualized oncolytic virus multivalent vaccine can infect tumor cells, express tumor antigens and eventually cells to uncover more tumor antigens. More importantly infection will activate the immune system and trigger an anti-tumor immunity against ovarian cancer-specific mutations, effectively reducing the chance of tumor cell escape through subcloning mutations. The study intends to illustrate the mechanism of vaccine immune reactivation in patients with ovarian cancer, evaluate tumor growth control by recombinant oncolytic in mouse ovarian models. This preclinical research provides insight into the design of novel personalized immunotherapy for recurrent ovarian cancer.

临床上复发性卵巢癌治疗药物的种类和疗效非常有限，针对卵巢癌患者肿瘤的基因组突变设计个体化新抗原neoantigen疫苗给复发性卵巢癌的治疗带来新的希望。本研究基于前期对5例晚期卵巢癌患者肿瘤外显子测序的结果，生物信息学预测得到125个针对患者的抗原表位，将人工合成这些抗原多肽，筛选鉴定针对卵巢癌患者的肿瘤特异性neoantigen，然后以痘苗溶瘤病毒为载体，插入对应卵巢癌患者肿瘤neoantigen，设计个体化溶瘤病毒多价复合疫苗，利用溶瘤病毒可以特异性感染卵巢癌细胞，在瓦解肿瘤同时又诱导免疫细胞向肿瘤组织浸润引发肿瘤特异性免疫应答，旨在调动针卵巢癌特异性突变的抗肿瘤免疫，减少异质性肿瘤细胞逃生的机会，并探讨疫苗重新活化卵巢癌患者的免疫微环境的机制，评估重组溶瘤毒疫苗在小鼠荷瘤模型中的抑瘤效果，为卵巢癌精准免疫治疗提供临床前研究依据。

免疫治疗对卵巢癌的疗效非常有限，其主要原因与卵巢癌低突变负荷和高免疫抑制肿瘤微环境相关，研究旨在探索一种基于肿瘤新抗原（neoantigen）和溶瘤病毒联合的晚期卵巢癌的潜在免疫疗法，设计一种携带多个来自卵巢癌患者neoantigen的痘苗溶瘤病毒（OVV），用于增强诱导肿瘤特异性CD8+T细胞应答，改善了肿瘤控制，并导致肿瘤中独特的免疫变化，改善卵巢癌动物模型预后。我们对9例高级别浆液性卵巢癌新鲜组进行全外显子组测序和基于机器学习的neoantigen预测，得到362个neoantigen。其中由5个新抗原肽组成的集合pool1。证明通过neoantigen特异性T细胞反应具有强免疫原性，导致卵巢癌细胞免疫原性细胞死亡（ICD）。然后，以删除F3L基因的牛痘溶瘤病毒作为免疫载体，构建共表达IL2和串联Pool1多肽的重组痘苗溶瘤病毒OVV-IL2- Pool1。通过卵巢癌类器官模型评估OVV-IL2- Pool1疗效的结果表明，OVV-IL2-Pool能够感染和溶解多例卵巢癌类器官并在肿瘤中扩散，而正常细胞基本不受伤害, 并增强异源卵巢癌的细胞死亡和neoantigen的免疫原性。采用超重度免疫缺陷小鼠NOG-dKO建立免疫系统人源化小鼠卵巢癌模型评估OVV-IL2- Pool1的疗效，结果表明OVV-IL2- Pool1较未治疗对照显著抑制肿瘤生长，其机制包括小鼠体内特异性溶瘤，瘤内原位扩增neoantigen诱导肿瘤微环境TILs富集促进卵巢癌ICD。而且，OVV-IL2- Pool1治疗小鼠体内IL6、IL10等细胞因子含量与未治疗对照差异不显著，提示其导致机体发生系统性炎症因子风暴的危险性极低。本项项目研发了针对卵巢癌患者新抗原设计的个体化溶瘤病毒疫苗，将为晚期、复发性、难治性卵巢癌治疗开拓新的方向。.