Immunotherapy with CD19-targeting bispecific T-cell engagers (CD19BiTEs) has demonstrated highly effective killing of cancer cells in patients with precursor acute lymphoblastic leukemia and non-Hodgkin’s lymphomas. However, there are some drawbacks to this therapy, such as toxicity, short half-life in the serum, and immunosuppressive tumor microenvironment that could limit the use of CD19BiTEs in the clinic. Here, we generate an oncolytic vaccinia virus (OVV) encoding a CD19-specific BiTE (OVV-CD19BiTE). We demonstrate that OVV-CD19BiTE’s ability to replicate and induce oncolysis was similar to that of its parental counterpart. Supernatants from OVV-CD19BiTE-infected cells could induce activation and proliferation of human T cells, and the bystander effect of the virus was also demonstrated. In vivo study showed that OVV-CD19BiTE selectively replicated within tumor tissue, and contributed to a more significantly increased percentage of CD3, CD8, and naïve CD8 T subpopulations within tumors in contrast to blinatumomab. More importantly, treatment with OVV-CD19BiTE both in vitro and in vivo resulted in potent antitumor activity in comparison with control OVV or blinatumomab, a first-in-class BiTE, thereby resulting in long-term tumor remissions without relapse. The study provides strong evidence for the therapeutic benefits of CD19-targeting BiTE expression by OVV, and suggests the feasibility of testing the approach in clinical trials.
采用CD19靶向双特异性T细胞衔接器（CD19BiTEs）的免疫疗法已在急性淋巴细胞白血病前体及非霍奇金淋巴瘤患者中展现出高效杀伤癌细胞的能力。然而该疗法存在毒性、血清半衰期短以及免疫抑制性肿瘤微环境等局限性，可能制约CD19BiTEs的临床应用。本研究构建了编码CD19特异性双特异性T细胞衔接器的溶瘤痘苗病毒（OVV-CD19BiTE），其复制能力与溶瘤效应与亲本病毒相似。感染OVV-CD19BiTE的细胞上清液可激活并促进人T细胞增殖，且该病毒展现出显著的旁观者效应。体内研究显示，与双特异性抗体药物贝林妥欧单抗相比，OVV-CD19BiTE能选择性地在肿瘤组织中复制，并显著提升肿瘤内CD3、CD8及初始CD8 T细胞亚群比例。更重要的是，相较于对照溶瘤痘苗病毒或首创型双特异性T细胞衔接器贝林妥欧单抗，OVV-CD19BiTE在体外和体内均表现出更强的抗肿瘤活性，可实现长期肿瘤缓解且无复发。本研究为溶瘤痘苗病毒表达CD19靶向双特异性T细胞衔接器的治疗优势提供了有力证据，并提示了该疗法进入临床试验的可行性。
肿瘤(癌症)患者之家