Getting oncolytic virus therapies off the ground

An international meeting was held on the development and application of replicating viruses for cancer therapy this past March in Banff, Alberta. In this review, using the presentations at this meeting as a backdrop, we discuss how recent scientific and clinical findings are reshaping the development of oncolytic virus therapeutics. Here we identify some of the obstacles that these therapeutics face and discuss evolving strategies, both preclinically and clinically, that are facilitating oncolytic virus development.     

溶瘤病毒的肿瘤临床应用研究进展

近年来,肿瘤免疫疗法已逐渐成为继手术、化疗、放疗之后的第四大肿瘤治疗手段。作为肿瘤免疫疗法之一的溶瘤病毒疗法,在沉寂了多年之后,再次成为关注的焦点。溶瘤病毒主要通过选择性杀伤肿瘤细胞和诱导机体产生特异性抗肿瘤免疫应答两种途径来实现肿瘤靶向治疗的目的,从而达到较好的抗肿瘤效果。更重要的是,当其与化疗药物、放疗、免疫检查点抑制剂、CAR-T细胞等疗法联合应用时,具有协同效应,进一步提高肿瘤治疗的效果,有着巨大的应用前景,有望成为未来肿瘤治疗的新方向。本文从常用的溶瘤病毒及其机制、临床应用现状、联合治疗和展望等方面进行综述。     

溶瘤病毒的临床应用

溶瘤病毒特异性地识别并感染肿瘤细胞最终导致细胞溶胀而摧毁肿瘤细胞，但无法在正常机体细胞内复制而不具有杀伤作用，理论上具有更高的效率和更低的副作用。目前已有多种病毒被用来改造成溶瘤病毒，包括新城疫病毒、单纯疱疹病毒-1、呼肠孤病毒、腺病毒等。虽然大多数的抗肿瘤效应目前仍停留在实验室研究及临床前期的动物试验阶段，但已有少量溶瘤病毒产品进入了临床试验应用，初步显示了其临床应用的安全性并取得了相当的效果，成为肿瘤治疗领域一种具发展潜力的治疗手段。     

溶瘤病毒靶向肿瘤微环境的研究进展

肿瘤微环境是肿瘤生长的生态位,在肿瘤的生长发展中具有极其重要的作用。利用溶瘤病毒靶向肿瘤微环境可以从多方面抑制肿瘤的发展。肿瘤微环境中含有的大量生长因子、细胞因子、免疫细胞、肿瘤浸润细胞及其胞外基质等均会抑制溶瘤病毒在肿瘤细胞中的复制增殖。我们通过各种手段可以改造肿瘤微环境进而提高溶瘤效率。     

溶瘤麻疹病毒抗瘤治疗“瓶颈”与破解对策

在肿瘤基因治疗领域,具有自我复制、能选择性杀伤肿瘤的溶瘤病毒已成为抗肿瘤治疗的有效武器之一。其中溶瘤麻疹病毒因其拥有极好的安全记录和优秀的抗瘤效果目前已经进入多项临床试验阶段。但是仍存在一些因素会影响溶瘤麻疹病毒成功治疗肿瘤,研究者们正在努力寻找对策以期破解这些瓶颈,使溶瘤麻疹病毒更好的发挥溶瘤作用。     

Studies on murine sarcoma virus: II. Detection of group-specific antigens by immunofluorescence

The group-specific (GS) antigen of murine tumor viruses was demonstrated by immunofluorescence in mouse cells recently infected by mouse sarcoma virus, strain Moloney (MSV-M), with the serum of rats carrying long-transplanted MSV-M tumors. GS antigen was detected 15 h post-infection and was also present in various mouse and rat cell lines chronically infected with murine tumor viruses. The antigen was strictly localized in the cytoplasm of infected cells and was also found in mouse and rat cells chronically infected by members of the two major subgroups of murine tumor viruses. Further, the sera employed were shown to contain exclusively GS antibodies and the tumors used for immunization were found by several techniques to be free of virus envelope (V) antigens after a given number of passages in vivo. V antigens were visible only at the cell membrane and the time course of appearance of both GS and V antigens in recently infected cells was parallel. In contrast, GS antigen was not observed in two hamster tumor lines transformed by MSV-M.     

Angiogenesis inhibition by an oncolytic herpes virus expressing interleukin 12.

PURPOSE: Oncolytic herpes simplex viruses (HSVs) may have significant antitumor effects resulting from the direct lysis of cancer cells. HSVs may also be used to express inserted transgenes to exploit additional therapeutic strategies. The ability of an interleukin (IL)-12-expressing HSV to treat squamous cell carcinoma (SCC) by inhibition of tumor angiogenesis is investigated in this study. EXPERIMENTAL DESIGN: A replication-competent, attenuated, oncolytic HSV carrying the murine IL-12 gene (NV1042), its non-cytokine-carrying analog (NV1023), or saline was used to treat established murine SCC flank tumors by intratumoral injection. The expression of secondary antiangiogenic mediators was measured. Angiogenesis inhibition was assessed by in vivo Matrigel plug assays, flank tumor subdermal vascularity, and in vitro endothelial cell tubule formation assay. RESULTS: Intratumoral injections of NV1042 (2 x 10(7) plaque-forming units) into murine SCC VII flank tumors resulted in smaller tumor volumes as compared with NV1023 or saline. IL-12 and IFN-gamma expression in tumors was 440 and 2.2 pg/mg, respectively, at 24 h after NV1042 injection, but both IL-12 and IFN-gamma were undetectable (<0.2 pg/mg) after NV1023 or saline injections. Expression of two antiangiogenesis mediators, monokine induced by IFN-gamma and IFN-inducible protein 10, was elevated after NV1042 treatment. Matrigel plug assays of NV1042-transfected SCC VII tumor cells demonstrated significantly decreased hemoglobin content and microvessel density as compared with NV1023 and PBS. Excised murine flank tumors treated with NV1042 had decreased subdermal vascularity as compared with NV1023 and PBS. Both splenocytes and IL-12 expression by NV1042 were required for in vitro inhibition of endothelial tubule formation. CONCLUSIONS: IL-12 expression by an oncolytic herpes virus enhances therapy of SCC through antiangiogenic mechanisms. Strategies combining HSV oncolysis with angiogenesis inhibition merit further investigation for potential clinical application.     

A genetically engineered influenza A virus with ras-dependent oncolytic properties.

The NS1 protein of influenza virus is a virulence factor that counteracts the PKR-mediated antiviral response by the host. As a consequence, influenza NS1 gene knockout virus delNS1 (an influenza A virus lacking the NS1 open reading frame) fails to replicate in normal cells but produces infectious particles in PKR-deficient cells. Because it is known that oncogenic ras induces an inhibitor of PKR, we addressed the question of whether the delNS1 virus selectively replicates in cells expressing oncogenic ras. We show that upon transfection and expression of oncogenic N-ras, cells become permissive for productive delNS1 virus replication, suggesting that the delNS1 virus has specific oncolytic properties. Viral growth in the oncogenic ras-transfected cells is associated with a reduction of PKR activation during infection. Moreover, treatment of s.c. established N-ras-expressing melanomas in severe combined immunodeficiency mice with the delNS1 virus revealed that this virus has tumor-ablative potentials. The delNS1 virus does not replicate in nonmalignant cell lines such as melanocytes, keratinocytes, or endothelial cells. The apathogenic nature of the delNS1 virus combined with the selective replication properties of this virus in oncogenic ras-expressing cells renders this virus an attractive candidate for the therapy of tumors with an activated ras-signaling pathway.     

间充质干细胞作为溶瘤病毒细胞载体的研究进展

溶瘤病毒能够在肿瘤细胞内大量增殖并最终裂解肿瘤细胞,同时还具有对肿瘤微环境的调控作用,激发宿主抗肿瘤免疫反应。但是溶瘤病毒经静脉注射后引发的机体抗病毒免疫应答以及溶瘤病毒的肿瘤靶向性差,使得临床上对肿瘤的疗效不佳。间充质干细胞具有肿瘤趋向性、免疫抑制功能和旁分泌效应。间充质干细胞运载溶瘤病毒既可以保护病毒不被免疫系统清除又可精准将病毒递送到肿瘤病变部位,同时病毒感染可改变间充质干细胞分泌的细胞因子谱,促进机体抗肿瘤免疫反应。因此,间充质干细胞运载溶瘤病毒是治疗复发/难治性实体肿瘤的理想选择。本文结合临床前及临床研究的有关进展,对间充质干细胞运载溶瘤病毒治疗实体肿瘤进行综述,为间充质干细胞运载溶瘤病毒的临床应用提供了理论依据。     

Nerve-sparing therapy with oncolytic herpes virus for cancers with neural invasion.

PURPOSE: The invasion of cancer cells along nerves is an ominous pathologic finding associated with poor outcomes for a variety of tumors, including pancreatic and head and neck carcinomas. Peripheral nerves may serve as a conduit for these cancers to track into the central nervous system. Cancer progression within nerves and surgical resection of infiltrated nerves result in a permanent loss of neural function, potentially causing cosmetic and functional morbidity. Herpes simplex viruses (HSV) have utility for gene transfer into nerves and as oncolytic agents. We studied the use of an attenuated HSV, NV1023, as treatment for cancers with neural invasion. EXPERIMENTAL DESIGN AND RESULTS: NV1023 injection into the sciatic nerves of nude mice had no toxic effect on nerve function, whereas similar doses of wild-type HSV-1 (F' strain) caused complete nerve paralysis within 4 days and 100% mortality at day 6. NV1023 showed effective cytotoxicity in vitro on three neurotrophic human carcinoma cell lines, including pancreatic (MiaPaCa2), squamous cell (QLL2), and adenoid cystic (ACC3) carcinomas. A model of neural invasion was established by implanting human carcinoma cells in the sciatic nerves of nude mice. All control group mice developed left hind limb paralysis 5 to 7 weeks after tumor injection, whereas animals treated with NV1023 maintained intact nerve function and showed significant tumor regression (P < 0.0001). CONCLUSIONS: These results show that NV1023 oncolytic therapy may effectively treat cancers with neural invasion and preserve neural function. These findings hold significant clinical implications for patients with cancer neural invasion.     

Synergy of a herpes oncolytic virus and paclitaxel for anaplastic thyroid cancer.

PURPOSE: Novel therapeutic regimens are needed to improve the dismal outcomes of patients with anaplastic thyroid cancer (ATC). Oncolytic herpes simplex virus have shown promising activity against human ATC. We studied the application of oncolytic herpes simplex virus (G207 and NV1023) in combination with currently used chemotherapeutic drugs (paclitaxel and doxorubicin) for the treatment of ATC. EXPERIMENTAL DESIGN AND RESULTS: All four agents showed dose-response cytotoxicity in vitro for the human ATC cell lines KAT4 and DRO90-1. G207, combined with paclitaxel, showed synergistic cytotoxicity. Chou-Talalay combination indices ranged from 0.56 to 0.66 for KAT4, and 0.68 to 0.74 for DRO90-1 at higher affected fractions. Paclitaxel did not enhance G207 viral entry and early gene expression or G207 viral replication. Paclitaxel combined with G207 compared with single-agent treatment or controls showed significantly increased microtubule acetylation, mitotic arrest, aberrant chromatid separation, inhibition of metaphase to anaphase progression, and apoptosis. A single i.t. injection of G207 combined with biweekly i.p. paclitaxel injections in athymic nude mice bearing KAT4 flank tumors showed significantly reduced mean tumor volume (74 +/- 38 mm(3)) compared with G207 alone (388 +/- 109 mm(3)), paclitaxel alone (439 +/- 137 mm(3)), and control (520 +/- 160 mm(3)) groups at 16 days. There was no morbidity in vivo attributable to therapy. CONCLUSIONS: Mechanisms of paclitaxel antitumoral activity, including microtubule acetylation, mitotic block, and apoptosis, were enhanced by G207, which also has direct oncolytic effects. Combination of G207 and paclitaxel therapy is synergistic in treating ATC and holds promise for patients with this fatal disease.     

Studies of FBJ osteosarcoma virus in tissue culture. II. Autoinhibition of focus formation.

A high-titered non-focus-forming virus, FBJ-MuLV (murine leukemia virus), present in FBJ tumor preparations, inhibited significantly the expression and production of FBJ-MuSV (murine sarcoma virus) in tissue culture. This "autoinhibition" was comparable to that observed when a 3- to 4-log excess of infectious MuLV was added to standard MuSV. The degree of inhibition was influenced by the tropism of the MuLV (or the ease of spread and propagation of MuLV in certain cells), multiplicity of infection by MuLV, amount of excess MuLV, and ability of the MuSV-transformed cells to replicate independently. The FBJ MuLV-MuSV complex may be a model system for the detection of sarcoma viruses in spontaneous tumors in various animals where inhibition by excess nontransforming virus could be an important biologic phenomenon.     

共表达BiTE的溶瘤病毒对胶质瘤的抗肿瘤活性研究

目的:探索编码BiTE的溶瘤病毒[分泌双特异性T细胞衔接器的单纯性孢疹病毒(herpes simplex virus-Bi-specific T-cell engagers,HSV-BiTE)]是否可以对胶质瘤产生显著的抗肿瘤活性.方法:荧光显微镜观察及Western blot检测HSV-BiTE对胶质瘤细胞U118的...