Oncolytic vaccinia virus GLV-1h68 exhibits profound antitumoral activities in cell lines originating from neuroendocrine neoplasms.

BACKGROUND: Oncolytic virotherapy is an upcoming treatment option for many tumor entities. But so far, a first oncolytic virus only was approved for advanced stages of malignant melanomas. Neuroendocrine tumors (NETs) constitute a heterogenous group of tumors arising from the neuroendocrine system at diverse anatomic sites. Due to often slow growth rates and (in most cases) endocrine non-functionality, NETs are often detected only in a progressed metastatic situation, where therapy options are still severely limited. So far, immunotherapies and especially immunovirotherapies are not established as novel treatment modalities for NETs. METHODS: In this immunovirotherapy study, pancreatic NET (BON-1, QGP-1), lung NET (H727, UMC-11), as well as neuroendocrine carcinoma (NEC) cell lines (HROC-57, NEC-DUE1) were employed. The well characterized genetically engineered vaccinia virus GLV-1 h68, which has already been investigated in various clinical trials, was chosen as virotherapeutical treatment modality. RESULTS: Profound oncolytic efficiencies were found for NET/NEC tumor cells. Besides, NET/NEC tumor cell bound expression of GLV-1 h68-encoded marker genes was observed also. Furthermore, a highly efficient production of viral progenies was detected by sequential virus quantifications. Moreover, the mTOR inhibitor everolimus, licensed for treatment of metastatic NETs, was not found to interfere with GLV-1 h68 replication, making a combinatorial treatment of both feasible. CONCLUSIONS: In summary, the oncolytic vaccinia virus GLV-1 h68 was found to exhibit promising antitumoral activities, replication capacities and a potential for future combinatorial approaches in cell lines originating from neuroendocrine neoplasms. Based on these preliminary findings, virotherapeutic effects now have to be further evaluated in animal models for treatment of Neuroendocrine neoplasms (NENs).

The Oncolytic Herpes Simplex Virus Talimogene Laherparepvec Shows Promising Efficacy in Neuroendocrine Cancer Cell Lines.

Metastatic neuroendocrine cancer still constitutes a palliative situation, lacking promising treatment options. Oncolytic virotherapy, a novel type of virus-based immunotherapy, lyses tumor cells using genetically engineered viruses thereby activating the immune system to induce an optimized antitumor response which could bring down tumor masses to a stage of minimal residual tumor disease. The oncolytic vector talimogene laherparepvec (T-VEC, herpes simplex virus [HSV] type 1) has already shown excellent safety profiles in clinical studies and has become the first ever FDA/EMA-approved oncolytic virus (OV). This work presents a first preclinical assessment of this state-of-the-art OV, using a panel of human neuroendocrine tumor/neuroendocrine carcinoma (NET/NEC) cell lines. Cytotoxicity, transgene expression, and viral replication patterns were studied. Furthermore, the antiproliferative activity was compared to the one of mTOR inhibitor Everolimus and also interactions between the OV and Everolimus were evaluated. Moreover, virostatic effects of ganciclovir (GCV) on replication of T-VEC were assessed and electron microscopic pictures were taken to comprehend viral envelopment and details of the replication cycle of T-VEC in human neuroendocrine cancer. It could be shown that T-VEC infects, replicates in, and lyses human NET/NEC cells exhibiting high oncolytic efficiencies already at quite low virus concentrations. Interestingly, Everolimus was not found to have any relevant impact on rates of viral replication, but no additive effects could be proved using a combinatorial therapy regimen. On the other hand, GCV was shown to be able to limit replication of T-VEC, thus establishing an important safety feature for future treatments of NET/NEC patients. Taken together, T-VEC opens up a promising novel treatment option for NET/NEC patients, warranting its further preclinical and clinical development.

Clinical management of NUT carcinoma (NC) in Germany: Analysis of survival, therapy response, tumor markers and tumor genome sequencing in 35 adult patients.

NUT carcinomas (NC) are very rare and highly aggressive tumors, molecularly defined by an aberrant gene fusion involving the NUTM1 gene. NCs preferentially arise intrathoracically or in the head and neck region, having a highly adverse prognosis with almost no long-term survivors. Here, we report on a cohort of 35 adult NC patients who were evaluated at University Hospital Tuebingen in an eight year time span, i.e. between 2016 and 2023. Primary objectives were overall survival (OS) and influence of primary tumor locations, fusion gene types and staging on OS. Secondary objectives were patient baseline characteristics, risk factors, tumor markers, treatment decisions and responses to therapy comparing thoracic vs non-thoracic origins. Further, data from tumor genome sequencing were analyzed. In this monocentric German cohort, 54 % of patients had thoracic tumors and 65 % harbored a BRD4-NUTM1 fusion gene. Median OS was 7.5 months, being significantly dependent on primary tumor location and nodal status. Initial misdiagnosis was a problem in 31 % of the cases. Surgery was the first treatment in most patients (46 %) and 80 % were treated with polychemotherapies, showing longer progression free survival (PFS) with ifosfamide-based than with platinum-based regimens. Patients treated with an immune checkpoint inhibitor (ICI) in addition to first-line chemotherapy tended to have longer OS. Initial LDH levels could be identified as a prognostic measure for survival prognosis. Sequencing data highlight aberrant NUTM1 fusion genes as unique tumor driver genes. This is the largest adult European cohort of this orphan tumor disease, showing epidemiologic and molecular features as well as relevant clinical data. Awareness to prevent misdiagnosis, fast contact to a specialized nation-wide center and referral to clinical studies are essential as long-term survival is rarely achieved with any of the current therapeutic regimes.

Efficacy of Different Oncolytic Vaccinia Virus Strains for the Treatment of Murine Peritoneal Mesothelioma.

Effective treatment options for peritoneal surface malignancies (PSMs) are scarce. Oncolytic virotherapy with recombinant vaccinia viruses might constitute a novel treatment option for PSM. We aimed to identify the most effective oncolytic vaccinia virus strain in two murine mesothelioma cell lines and the oncolytic potential in a murine model of peritoneal mesothelioma. Cell lines AB12 and AC29 were infected in vitro with vaccinia virus strains Lister (GLV-1h254), Western Reserve (GLV-0b347), and Copenhagen (GLV-4h463). The virus strain GLV-0b347 was shown most effective in vitro and was further investigated by intraperitoneal (i.p.) application to AB12 and AC29 mesothelioma-bearing mice. Feasibility, safety, and effectiveness of virotherapy were assessed by evaluating the peritoneal cancer index (PCI), virus detection in tumor tissues and ascites, virus growth curves, and comparison of overall survival. After i.p. injection of GLV-0b347, virus was detected in both tumor cells and ascites. In comparison to mock-treated mice, overall survival was significantly prolonged, ascites was less frequent and PCI values declined. However, effective treatment was only observed in animals with limited tumor burden at the time point of virus application. Nonetheless, intraperitoneal virotherapy with GLV-0b347 might constitute a novel therapeutic option for the treatment of peritoneal mesothelioma. Additional treatment modifications and combinational regimes will be investigated to further enhance treatment efficacy.

Establishing a New Platform to Investigate the Efficacy of Oncolytic Virotherapy in a Human Ex Vivo Peritoneal Carcinomatosis Model.

Oncolytic virotherapy constitutes a promising treatment option for many solid cancers, including peritoneal carcinomatosis (PC), which still represents a terminal stage of many types of tumors. To date, the in vitro efficacy of oncolytic viruses is mostly tested in 2D-cultured tumor cell lines due to the lack of realistic 3D in vitro tumor models. We have investigated the feasibility of virotherapy as a treatment option for PC in a human ex vivo peritoneum co-culture model. Human HT-29 cancer cells stably expressing marker genes GFP and firefly luciferase (GFP/luc) were cultured on human peritoneum and infected with two prototypic oncolytic viruses (GLV-0b347 and MeV-DsRed). Both viral constructs were able to infect HT-29 cells in patient-derived peritoneum with high tumor specificity. Over time, both GFP signal and luciferase activity decreased substantially, thereby indicating successful virus-induced oncolysis. Furthermore, immunohistochemistry stainings showed specific virotherapeutic infections of HT-29 cells and effective tumor cell lysis in infected co-cultures. Thus, the PC model established here provides a clinically relevant screening platform to evaluate the therapeutic efficacy of virotherapeutic compounds and also to investigate, in an autologous setting, the immunostimulatory potential of oncolytic viruses for PC in a unique human model system superior to standard 2D in vitro models.

Case report: Immunovirotherapy as a novel add-on treatment in a patient with thoracic NUT carcinoma.

NUT carcinoma (NC) is a rare and extremely aggressive form of cancer, usually presenting with intrathoracic or neck manifestations in adolescents and young adults. With no established standard therapy regimen and a median overall survival of only 6.5 months, there is a huge need for innovative treatment options. As NC is genetically driven by a single aberrant fusion oncoprotein, it is generally characterized by a low tumor mutational burden, thus making it immunologically cold and insusceptible to conventional immunotherapy. Recently, we have demonstrated that oncolytic viruses (OVs) are able to specifically infect and lyse NC cells, thereby turning an immunologically cold tumor microenvironment into a hot one. Here, we report an intensive multimodal treatment approach employing for the first time an OV (talimogene laherparepvec (T-VEC); IMLYGIC®) together with the immune checkpoint inhibitor pembrolizumab as an add-on to a basic NC therapy (cytostatic chemotherapy, radiation therapy, epigenetic therapy) in a patient suffering from a large thoracic NC tumor which exhibits an aberrant, unique BRD3:NUTM1 fusion. This case demonstrates for the first time the feasibility of this innovative add-on immunovirotherapy regimen with a profound, repetitive and durable replication of T-VEC that is instrumental in achieving tumor stabilization and improvement in the patient´s quality of life. Further, a previously unknown BRD3:NUTM1 fusion gene was discovered that lacks the extraterminal domain of BRD3.

Three-dimensional tumor cell cultures employed in virotherapy research.

Oncolytic virotherapy constitutes an upcoming alternative treatment option for a broad spectrum of cancer entities. However, despite great research efforts, there is still only a single US Food and Drug Administration/European Medicines Agency-approved oncolytic virus available for clinical use. One reason for that is the gap between promising preclinical data and limited clinical success. Since oncolytic viruses are biological agents, they might require more realistic in vitro tumor models than common monolayer tumor cell cultures to provide meaningful predictive preclinical evaluation results. For more realistic invitro tumor models, three-dimensional tumor cell-culture systems can be employed in preclinical virotherapy research. This review provides an overview of spheroid and hydrogel tumor cell cultures, organotypic tumor-tissue slices, organotypic raft cultures, and tumor organoids utilized in the context of oncolytic virotherapy. Furthermore, we also discuss advantages, disadvantages, techniques, and difficulties of these three-dimensional tumor cell-culture systems when applied specifically in virotherapy research.