Oncolytic Vaccinia Research Articles

Inactivation of the UL37 Deamidase Enhances Virus Replication and Spread of the HSV-1(VC2) Oncolytic Vaccine Strain and Secretion of GM-CSF.

The HSV-1 (VC2) live-attenuated vaccine strain was engineered with specific deletions in the amino termini of glycoprotein K (gK) and membrane protein UL20, rendering the virus unable to enter neurons and establish latency. VC2 replicates efficiently in epithelial cell culture but produces lower viral titers and smaller viral plaques than its parental HSV-1 (F) wild-type virus. VC2 is an effective live-attenuated vaccine against HSV-1 and HSV-2 infections in mice and guinea pigs and an anti-tumor immunotherapeutic and oncolytic virus against melanoma and breast cancer in mouse models. Previously, we reported that the gK/UL20 complex interacts with the UL37 tegument protein, and this interaction is essential for virion intracellular envelopment and egress. To investigate the potential role of the UL37 deamidase functions, the recombinant virus FC819S and VC2C819S were constructed with a C819S substitution to inactivate the UL37 predicted deamidase active site on an HSV-1(F) and HSV-1(VC2) genetic background, respectively. FC819S replicated to similar levels with HSV-1(F) and produced similar size viral plaques. In contrast, VC2C819S replication was enhanced, and viral plaques increased in size, approaching those of the wild-type HSV-1(F) virus. FC819S infection of cell cultures caused enhanced GM-CSF secretion in comparison to HSV-1(F) across several cell lines, including HEp2 cells and cancer cell lines, DU145 (prostate) and Panc 04.03 (pancreas), and primary mouse peritoneal cells. VC2 infection of these cell lines caused GM-CSF secretion at similar levels to FC819S infection. However, the VC2C819S virus did not exhibit any further enhancement of GM-CSF secretion compared to the VC2 virus. These results suggest that the UL37 deamidation functions in conjunction with the gK/UL20 complex to facilitate virus replication and GM-CSF secretion.

Virotherapy combined with anti-PD-1 transiently reshapes the tumor immune environment and induces anti-tumor immunity in a preclinical PDAC model.

Pancreatic ductal adenocarcinoma (PDAC) is largely refractory to cancer immunotherapy with PD-1 immune checkpoint blockade (ICB). Oncolytic virotherapy has been shown to synergize with ICB. In this work, we investigated the combination of anti-PD-1 and oncolytic measles vaccine in an immunocompetent transplantable PDAC mouse model. We characterized tumor-infiltrating T cells by immunohistochemistry, flow cytometry and T cell receptor sequencing. Further, we performed gene expression profiling of tumor samples at baseline, after treatment, and when tumors progressed. Moreover, we analyzed systemic anti-tumor and anti-viral immunity. Combination treatment significantly prolonged survival compared to monotherapies. Tumor-infiltrating immune cells were increased after virotherapy. Gene expression profiling revealed a unique, but transient signature of immune activation after combination treatment. However, systemic anti-tumor immunity was induced by virotherapy and remained detectable even when tumors progressed. Anti-PD-1 treatment did not impact anti-viral immunity. Our results indicate that combined virotherapy and ICB induces anti-tumor immunity and reshapes the tumor immune environment. However, further refinement of this approach may be required to develop its full potential and achieve durable efficacy.

Safety study supports clinical development of immunotherapeutic oncolytic measles vaccine

In a recent article in Molecular Therapy – Methods and Clinical Development, Galanis and co-authors presented pre-clinical safety data for a cancer immunotherapy derived from a measles vaccine strain, engineered to encode a bacterial immunomodulator.1 These data supported a successful investigational new drug (IND) application for a phase I clinical trial for patients suffering from metastatic breast cancer that is now ongoing. Despite limitations of the mouse model, the pre-clinical data from the present study and prior work are encouraging.

Abstract CT036: CORE1: Phase 2, single arm study of CG0070 combined with pembrolizumab in patients with non-muscle invasive bladder cancer (NMIBC) unresponsive to Bacillus Calmette-Guerin (BCG)

Abstract Introduction: CG0070, is an Ad5-based oncolytic vaccine engineered to express GM-CSF and replicate selectively in tumor cells with mutated or deficient RB. The CG0070 mechanism of action includes cell lysis and immunogenic cell death which is enhanced in the presence of GM-CSF. In an open label ph. 2 study, an overall CR rate of 62% and a CR at 12 months (m) of 29% have been observed in patients with high risk NMIBC previously treated with BCG. IV pembrolizumab, was recently approved by the FDA for patients with BCG-unresponsive CIS (with or without papillary tumors) with an overall complete RR of 41% and a 12 m CR rate of ~20%.This ph. 2 study will assess the potential synergy of the two agents in the treatment of BCG-unresponsive NMIBC. Methods:35 pts with BCG-unresponsive CIS with or without concurrent Ta or T1 disease will be treated with intravescical CG0070 (1x1012 vp) in combination with pembrolizumab at a dose of 400 mg IV q6 weeks. CG0070 will be administered weekly x 6 as induction followed by weekly x 3 maintenance instillations at months 3, 6, 9, 12, and 18. Pts with persistent CIS or HG Ta at 3 m may receive re-induction with weekly x 6 of CG0070. Pembrolizumab will be administered up to 24 m. Assessment of response will include q 3 m cystoscopy with biopsy of areas suspicious for disease, urine cytology, CTU/MRU, and mandatory bladder mapping biopsies at 12 m. Recurrence of HG disease will be enumerated as disease recurrence. The primary endpoint of the study is CR at 12 m. Secondary endpoints will include CR at any time, progression free survival, duration of response, cystectomy free survival and the safety of the combination. Correlate assessments will include changes in the tumor immune microenvironment, systemic immune induction, viral replication and transgene expression. Baseline expression of PD-L1, coxsackie adenovirus receptor, E2F transcription factor as well as anti-Ad5 Ab titer will be correlated with tumor response. Results: Thus far, 10 patients are evaluable at the 3 m timepoint for efficacy. Assessment of these 10 pts demonstrates 100% CR at 3 mos. Six of the 10 pts have also reached the 6 m hallmark in a CR as well as 2 at the 12 mos timepoint. Treatment related AE have been limited to transient grade 1-2 local-regional genitourinary adverse events with no grade 3 or 4 treatment related AE reported date. Conclusions: This initial data on the efficacy and safety of CG0070 plus pembrolizumab for the treatment of BCG unresponsive NMIBC is encouraging. An update on the study will be provided at the time of presentation. Citation Format: Roger Li, Gary Steinberg, Paras Shah, Ed Uchio, Donald Lamm, Trinity Bivalacqua, Vignesh Packiam, Ashish Kamat, Michael Chisamore, John McAdory, Paola Grandi, Jee-Hyun Kim, James Burke. CORE1: Phase 2, single arm study of CG0070 combined with pembrolizumab in patients with non-muscle invasive bladder cancer (NMIBC) unresponsive to Bacillus Calmette-Guerin (BCG) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT036.

CORE1: Phase 2, single-arm study of CG0070 combined with pembrolizumab in patients with nonmuscle-invasive bladder cancer (NMIBC) unresponsive to bacillus Calmette-Guerin (BCG).

4597 Background: CG0070, is an Ad5-based oncolytic vaccine engineered to express GM-CSF and replicate selectively in tumor cells with mutated or deficient RB. The CG0070 mechanism of action includes cell lysis and immunogenic cell death which is enhanced in the presence of GM-CSF. In an open label ph. 2 study, an overall CR rate of 62% and a CR at 12 months (m) of 29% have been observed in patients with high risk NMIBC previously treated with BCG. IV pembrolizumab, was recently approved by the FDA for patients with BCG-unresponsive CIS (with or without papillary tumors) with an overall complete RR of 41% and a 12 m CR rate of ̃20%. This ph. 2 study will assess the potential synergy of the two agents in the treatment of BCG-unresponsive NMIBC. Methods: 35 pts with BCG-unresponsive CIS with or without concurrent Ta or T1 disease will be treated with intravescical CG0070 (1x1012 vp) in combination with pembrolizumab at a dose of 400 mg IV q6 weeks. CG0070 will be administered weekly x 6 as induction followed by weekly x 3 maintenance instillations at months 3, 6, 9, 12, and 18. Pts with persistent CIS or HG Ta at 3 m may receive re-induction with weekly x 6 of CG0070. Pembrolizumab will be administered up to 24 m. Assessment of response will include q 3 m cystoscopy with biopsy of areas suspicious for disease, urine cytology, CTU/MRU, and mandatory bladder mapping biopsies at 12 m. Recurrence of HG disease will be enumerated as disease recurrence. The primary endpoint of the study is CR at 12 m. Secondary endpoints will include CR at any time, progression free survival, duration of response, cystectomy free survival and the safety. Correlate assessments will include changes in the tumor immune microenvironment, systemic immune induction,viral replication and transgene expression. Baseline expression of PD-L1, coxsackie adenovirus receptor, E2F transcription factor as well as anti-Ad5 Ab titer will be correlated with tumor response. Results: A CR rate of 87.5% (14/16) at the 3 m assessment timepoint has been observed thus far. All patients in CR at 3 m remain in CR at downstream timepoints including: 9/9 at 6 m, 6/6 at 9 m, and 3/3 at 12 m. Treatment related AE have been generally limited to transient grade 1-2 local-regional genitourinary adverse events with no reports of grade 3, 4 or SAE attributed to treatment with CG0070/Pembroluzimab. Conclusions: This initial data on the efficacy and safety of CG0070 plus pembrolizumab for the treatment of BCG unresponsive NMIBC is encouraging. Additional data on efficacy as well as safety and biomarker (CAR, E2F, and PDL1) assessment will be presented for at least 25 of the projected 35 patients at the time of the conference. Clinical trial information: NCT04387461.

Targeting oncometabolism to maximize immunotherapy in malignant brain tumors.

Brain tumors result in significant morbidity and mortality in both children and adults. Recent data indicates that immunotherapies may offer a survival benefit after standard of care has failed for malignant brain tumors. Modest results from several late phase clinical trials, however, underscore the need for more refined, comprehensive strategies that incorporate new mechanistic and pharmacologic knowledge. Recently, oncometabolism has emerged as an adjunct modality for combinatorial treatment approaches necessitated by the aggressive, refractory nature of high-grade glioma and other progressive malignant brain tumors. Manipulation of metabolic processes in cancer and immune cells that comprise the tumor microenvironment through controlled targeting of oncogenic pathways may be utilized to maximize the efficacy of immunotherapy and improve patient outcomes. Herein, we summarize preclinical and early phase clinical trial research of oncometabolism-based therapeutics that may augment immunotherapy by exploiting the biochemical and genetic underpinnings of brain tumors. We also examine metabolic pathways related to immune cells that target tumor cells, termed ‘tumor immunometabolism’. Specifically, we focus on glycolysis and altered glucose metabolism, including glucose transporters, hexokinase, pyruvate dehydrogenase, and lactate dehydrogenase, glutamine, and we discuss targeting arginase, adenosine, and indoleamine 2,3-dioxygenase (IDO), and toll-like receptors. Lastly, we summarize future directions targeting metabolism in combination with emerging therapies such as oncolytic virotherapy, vaccines, and chimeric antigen receptor T cells.

Peptides-Coated Oncolytic Vaccines for Cancer Personalized Medicine.

Oncolytic Viruses (OVs) work through two main mechanisms of action: the direct lysis of the virus-infected cancer cells and the release of tumor antigens as a result of the viral burst. In this sc.enario, the OVs act as in situ cancer vaccines, since the immunogenicity of the virus is combined with tumor antigens, that direct the specificity of the anti-tumor adaptive immune response. However, this mechanism in some cases fails in eliciting a strong specific T cell response. One way to overcome this problem and enhance the priming efficiency is the production of genetically modified oncolytic viruses encoding one or more tumor antigens. To avoid the long and expensive process related to the engineering of the OVs, we have exploited an approach based on coating OVs (adenovirus and vaccinia virus) with tumor antigens. In this work, oncolytic viruses encoding tumor antigens and tumor antigen decorated adenoviral platform (PeptiCRAd) have been used as cancer vaccines and evaluated both for their prophylactic and therapeutic efficacy. We have first tested the oncolytic vaccines by exploiting the OVA model, moving then to TRP2, a more clinically relevant tumor antigen. Finally, both approaches have been investigated in tumor neo-antigens settings. Interestingly, both genetically modified oncolytic adenovirus and PeptiCRAd elicited T cells-specific anti-tumor responses. However, in vitro cross-representation experiments, showed an advantage of PeptiCRAd as regards the fast presentation of the model epitope SIINFEKL from OVA in an immunogenic rather than tolerogenic fashion. Here two approaches used as cancer oncolytic vaccines have been explored and characterized for their efficacy. Although the generation of specific anti-tumor T cells was elicited in both approaches, PeptiCRAd retains the advantage of being rapidly adaptable by coating the adenovirus with a different set of tumor antigens, which is crucial in personalized cancer vaccines clinical setting.

Glycoconjugate Nanoparticle-Based Systems in Cancer Immunotherapy: Novel Designs and Recent Updates.

For many years, cell-surface glycans (in particular, Tumor-Associated Carbohydrate Antigens, TACAs) have been the target of both passive and active anticancer immunotherapeutic design. Recent advances in immunotherapy as a treatment for a variety of malignancies has revolutionized anti-tumor treatment regimens. Checkpoint inhibitors, Chimeric Antigen Receptor T-cells, Oncolytic virus therapy, monoclonal antibodies and vaccines have been developed and many approvals have led to remarkable outcomes in a subset of patients. However, many of these therapies are very selective for specific patient populations and hence the search for improved therapeutics and refinement of techniques for delivery are ongoing and fervent research areas. Most of these agents are directed at protein/peptide epitopes, but glycans–based targets are gaining in popularity, and a handful of approved immunotherapies owe their activity to oligosaccharide targets. In addition, nanotechnology and nanoparticle-derived systems can help improve the delivery of these agents to specific organs and cell types based on tumor-selective approaches. This review will first outline some of the historical beginnings of this research area and subsequently concentrate on the last 5 years of work. Based on the progress in therapeutic design, predictions can be made as to what the future holds for increasing the percentage of positive patient outcomes for optimized systems.

A novel immunopeptidomic-based pipeline for the generation of personalized oncolytic cancer vaccines.

Besides the isolation and identification of major histocompatibility complex I-restricted peptides from the surface of cancer cells, one of the challenges is eliciting an effective antitumor CD8+ T-cell-mediated response as part of therapeutic cancer vaccine. Therefore, the establishment of a solid pipeline for the downstream selection of clinically relevant peptides and the subsequent creation of therapeutic cancer vaccines are of utmost importance. Indeed, the use of peptides for eliciting specific antitumor adaptive immunity is hindered by two main limitations: the efficient selection of the most optimal candidate peptides and the use of a highly immunogenic platform to combine with the peptides to induce effective tumor-specific adaptive immune responses. Here, we describe for the first time a streamlined pipeline for the generation of personalized cancer vaccines starting from the isolation and selection of the most immunogenic peptide candidates expressed on the tumor cells and ending in the generation of efficient therapeutic oncolytic cancer vaccines. This immunopeptidomics-based pipeline was carefully validated in a murine colon tumor model CT26. Specifically, we used state-of-the-art immunoprecipitation and mass spectrometric methodologies to isolate >8000 peptide targets from the CT26 tumor cell line. The selection of the target candidates was then based on two separate approaches: RNAseq analysis and HEX software. The latter is a tool previously developed by Jacopo, 2020, able to identify tumor antigens similar to pathogen antigens in order to exploit molecular mimicry and tumor pathogen cross-reactive T cells in cancer vaccine development. The generated list of candidates (26 in total) was further tested in a functional characterization assay using interferon-γ enzyme-linked immunospot (ELISpot), reducing the number of candidates to six. These peptides were then tested in our previously described oncolytic cancer vaccine platform PeptiCRAd, a vaccine platform that combines an immunogenic oncolytic adenovirus (OAd) coated with tumor antigen peptides. In our work, PeptiCRAd was successfully used for the treatment of mice bearing CT26, controlling the primary malignant lesion and most importantly a secondary, nontreated, cancer lesion. These results confirmed the feasibility of applying the described pipeline for the selection of peptide candidates and generation of therapeutic oncolytic cancer vaccine, filling a gap in the field of cancer immunotherapy, and paving the way to translate our pipeline into human therapeutic approach.

Recipharm acquires 2 biologics firms

Recipharm, a Swedish pharmaceutical services firm, has acquired Arranta Bio, a contract development and manufacturing organization (CDMO) specializing in microbiome therapeutics and messenger RNA production. It also bought Vibalogics, a virotherapy CDMO with expertise in making oncolytic viruses, viral vaccines, and gene therapies. Both firms are based in Massachusetts. Meanwhile, Recipharm plans to expand its sterile fill-and-finish capabilities at its facility in Monts, France, by adding a high-speed filling line.

Targets of immunotherapy for hepatocellular carcinoma: An update.

Hepatocellular carcinoma, the most common primary liver cancer, in an immunogenic tumor with a poor prognosis because these tumors are diagnosed at late stages. Although, surgical resection, ablation, liver transplant, and locoregional therapies are available for early stages; however, there are yet no effective treatment for advanced and recurrent tumors. Immune checkpoint inhibitor therapy and adoptive cell transfer therapy has gained the popularity with some positive results because these therapies overcome anergy and systemic immune suppression. However, still there is a lack of an effective treatment and thus there is an unmet need of a novel treatment. At present, the focus of the research is on oncolytic viral therapy and combination therapy where therapies including radiotherapy, immune checkpoint therapy, adoptive cell transfer therapy, and vaccines are combined to get an additive or synergistic effect enhancing the immune response of the liver with a cytotoxic effect on tumor cells. This review discusses the recent key development, the basis of drug resistance, immune evasion, immune tolerance, the available therapies based on stage of the tumor, and the ongoing clinical trials on immune checkpoint inhibitor therapy, adoptive cell transfer therapy, oncolytic viral vaccine therapy, and combination therapy.

Oncolytic measles vaccines encoding PD-1 and PD-L1 checkpoint blocking antibodies to increase tumor-specific T cell memory

PD-1/PD-L1 checkpoint blockade has achieved unprecedented success in cancer immunotherapy. Nevertheless, many immune-excluded tumors are resistant to therapy. Combination with oncolytic virotherapy may overcome resistance by inducing acute inflammation, immune cell recruitment, and remodeling of the tumor immune environment. Here, we assessed the combination of oncolytic measles vaccine (MV) vectors and PD-1/PD-L1 blockade. In the MC38cea model of measles virus oncolysis, MV combined with anti-PD-1 and MV vectors encoding anti-PD-1 or anti-PD-L1 antibodies achieved modest survival benefits compared with control MV or vectors encoding the antibody constant regions only. Analyses of tumor samples and tumor-draining lymph nodes revealed slight increases in intratumoral T cell effector cytokines as well as a shift toward an effector memory phenotype in the T cell compartment. Importantly, increased IFN-γ recall responses were observed in tumor rechallenge experiments with mice in complete tumor remission after treatment with MV encoding anti-PD-1 or anti-PD-L1 compared with control MV. These results prompted us to generate MV encoding the clinically approved agents pembrolizumab and nivolumab. Previously, we have generated MV encoding atezolizumab. We demonstrated the functionality of the novel vectors in vitro. We envision these vectors as therapeutics that induce and support durable anti-tumor immune memory.

A New Generation of Vaccines in the Age of Immunotherapy

Purpose of reviewCancer vaccines are one of the most extensively studied immunotherapy type in solid tumors. Despite favorable presuppositions, so far, the use of cancer vaccines has been associated with disappointing results. However, a new generation of vaccines has been developed, promising to revolutionize the immunotherapy field.Recent findingsIn this review, we aim to highlight the advances in cancer vaccines and the remaining hurdles to overcome.SummaryCancer vaccination has experienced tremendous progress in the last decade, with myriad promising developments. Future efforts should focus on optimization of target identification, streamlining of most appropriate vaccination strategies, and adjuvant development, as well as predictive biomarker identification. Cautious optimism is warranted in the face of early successes seen in recent clinical trials for oncolytic vaccines. If an approach were to prove successful, it could revolutionize cancer therapy the way ICIs did in the previous decade.

Adenovirus Type 6: Subtle Structural Distinctions from Adenovirus Type 5 Result in Essential Differences in Properties and Perspectives for Gene Therapy

Adenovirus vectors are the most frequently used agents for gene therapy, including oncolytic therapy and vaccine development. It’s hard to overestimate the value of adenoviruses during the COVID-19 pandemic as to date four out of four approved viral vector-based SARS-CoV-2 vaccines are developed on adenovirus platform. The vast majority of adenoviral vectors are based on the most studied human adenovirus type 5 (HAdV-C5), however, its immunogenicity often hampers the clinical translation of HAdV-C5 vectors. The search of less seroprevalent adenovirus types led to another species C adenovirus, Adenovirus type 6 (HAdV-C6). HAdV-C6 possesses high oncolytic efficacy against multiple cancer types and remarkable ability to induce the immune response towards carrying antigens. Being genetically very close to HAdV-C5, HAdV-C6 differs from HAdV-C5 in structure of the most abundant capsid protein, hexon. This leads to the ability of HAdV-C6 to evade the uptake by Kupffer cells as well as to distinct opsonization by immunoglobulins and other blood proteins, influencing the overall biodistribution of HAdV-C6 after systemic administration. This review describes the structural features of HAdV-C6, its interaction with liver cells and blood factors, summarizes the previous experiences using HAdV-C6, and provides the rationale behind the use of HAdV-C6 for vaccine and anticancer drugs developments.

A modular self-adjuvanting cancer vaccine combined with an oncolytic vaccine induces potent antitumor immunity

Functional tumor-specific cytotoxic T cells elicited by therapeutic cancer vaccination in combination with oncolytic viruses offer opportunities to address resistance to checkpoint blockade therapy. Two cancer vaccines, the self-adjuvanting protein vaccine KISIMA, and the recombinant oncolytic vesicular stomatitis virus pseudotyped with LCMV-GP expressing tumor-associated antigens, termed VSV-GP-TAA, both show promise as a single agent. Here we find that, when given in a heterologous prime-boost regimen with an optimized schedule and route of administration, combining KISIMA and VSV-GP-TAA vaccinations induces better cancer immunity than individually. Using several mouse tumor models with varying degrees of susceptibility for viral replication, we find that priming with KISIMA-TAA followed by VSV-GP-TAA boost causes profound changes in the tumor microenvironment, and induces a large pool of poly-functional and persistent antigen-specific cytotoxic T cells in the periphery. Combining this heterologous vaccination with checkpoint blockade further improves therapeutic efficacy with long-term survival in the spectrum. Overall, heterologous vaccination with KISIMA and VSV-GP-TAA could sensitize non-inflamed tumors to checkpoint blockade therapy.

Abstract 2623: Investigation into factors influencing probability of success in oncology clinical trials and trends over time

Abstract The regulatory approval process for new therapies in oncology involves costly clinical trials that can span multiple years and historically have had a low probability of success. To derive estimates of the probability of success and other related risk characteristics in oncology clinical trials, we searched Informa Pharma Intelligence's Trialtrove and Pharmaprojects databases for oncology-specific drug-indication programs between 2001 and 2020. In total, we identified 10,083 oncology-specific drug-indication programs, which included 2,800 therapeutic agents (excluding biosimilars) tested across 98 indications. The features we considered included indication and indication group, clinical phase, follow-on indication status, presence and type of patient selection biomarker, drug modality, and accelerated approval status. In several cases, clinical success rates were higher than the benchmark oncology historical average of the phase 1 to approval success rate of 4.1% found in our sample set. For example, the use of pre-selection biomarkers in early clinical development was associated with a greater than two-fold increase in probability of approval from phase 1. Moreover, drugs with prior approvals in another indication were more than three times more likely to be successful from phase 1 than a candidate targeting a novel mechanism. In addition, we found that monoclonal antibodies were numerically more successful than other modalities in the historical data, while oncolytic viruses, vaccines, and bispecific antibodies have been less successful. In all cases, concomitant with the emergence of genomic technologies, an improved scientific understanding of cancer biology, and an evolving regulatory environment that includes a higher number of accelerated approvals, success rates in oncology have improved during the time period of this analysis and particularly in the past 5 years. Citation Format: Mary Jane Hinrichs, Shomesh E. Chaudhuri, Robert Bowden, Andrew W. Lo, David W. Jenkins. Investigation into factors influencing probability of success in oncology clinical trials and trends over time [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2623.

Synergistic Effect of NF-κB Signaling Pathway Inhibitor and Oncolytic Measles Virus Vaccine Strain against Lung Cancer and Underlying Mechanisms

背景与目的肺癌已成为我国发病率和死亡率居首位的恶性肿瘤。能自我复制、选择性杀伤肿瘤的溶瘤病毒，是治疗恶性肿瘤的有效策略，而其中溶瘤麻疹病毒疫苗株因其良好的溶瘤效果，且对正常细胞无损伤或微损伤，已进入几项临床试验。本研究旨在探讨核转录因子κB（nuclear factor kappa B, NF-κB）信号通路抑制剂与溶瘤麻疹病毒疫苗株协同抗肺癌的作用及机制。方法应用Western blot方法检测MV-Edm感染人肺癌细胞A549和H1299并应用细胞自噬相关的siRNA或者应用NF-кB通路抑制剂PS1145后SQSTM1、p-IκBα、IκBα、PARP及BAX的表达水平，运用流式细胞术分析各组细胞凋亡率的变化，同时采用噻唑蓝[3-(4, 5)-dimethylthiahiazo(-z-y1)-3, 5-di-phenytetrazoliumromide, MTT]法检测各组细胞的存活率。结果Western blot结果显示MV-Edm感染人肺癌细胞A549和H1299后，自噬引起NF-κB通路的激活，进而抑制细胞凋亡。抑制细胞自噬可抑制NF-κB通路的激活，MV-Edm感染后p-IκBα表达水平随着感染时间有不同程度的升高，IκBα的表达水平则降低，NF-κB通路抑制剂PS1145可促进人肺癌细胞A549和H1299凋亡（P < 0.01），并增强其溶瘤效果。结论NF-κB信号通路抑制剂PS1145与溶瘤麻疹病毒疫苗株联合可促进人肺癌细胞A549和H1299凋亡，并增强其溶瘤效果。

Prospects of immune checkpoint blockade and vaccine-based immunotherapy for glioblastoma

AbstractGlioblastoma multiforme (GBM) is the most prevalent primary brain tumor endowed with a dismal prognosis. Nowadays, immunotherapy in a particular immune checkpoint blockade and therapeutic vaccines are being extensively pursued. Yet, several characteristics of GBM may impact such immunotherapeutic approaches. This includes tumor heterogeneity, the relatively low mutational load of primary GBM, insufficient delivery of antibodies to tumor parenchyma and the unique immunosuppressive microenvironment of GBM. Moreover, standard treatment of GBM, comprising temozolomide chemotherapy, radiotherapy and in most instances the application of glucocorticoids for management of brain edema, results in a further increased immunosuppression. This review will provide a brief introduction to the principles of vaccine-based immunotherapy and give an overview of the current clinical studies, which employed immune checkpoint inhibitors, oncolytic viruses-based vaccination, cell-based and peptide-based vaccines. Recent experiences as well as the latest developments are reviewed. Overcoming obstacles, which limit the induction and long-term immune response against GBM when using vaccination approaches, are necessary for the implementation of effective immunotherapy of GBM.

Design and Engineering of Deimmunized Vaccinia Viral Vectors.

Vaccinia viral (VV) vectors are increasingly used in oncolytic virus therapy and vaccine development for cancer and infectious diseases. However, their effectiveness is hindered by the strong anti-viral immune response induced by the viral vector. In this review, we discuss the strategies to deimmunize vaccinia viral vector. One approach is to mask the virus from the neutralization antibody responses by mapping and eliminating of B-cell epitopes on the viral membrane proteins. The recombinant VVs contain one or more viral glycoproteins with mutations in the neutralizing antibody epitopes, resulting in viral escape from neutralization. In addition, a regulator of complement activation (e.g., CD55) can be expressed on the surface of the virus particle, leading to increased resistance to complement-mediated neutralization.

Oncolytic Rhabdovirus Vaccine Boosts Chimeric Anti-DEC205 Priming for Effective Cancer Immunotherapy

Prime-boost vaccination employing heterologous viral vectors encoding an antigen is an effective strategy to maximize the antigen-specific immune response. Replication-deficient adenovirus serotype 5 (Ad5) is currently being evaluated clinically in North America as a prime in conjunction with oncolytic rhabdovirus Maraba virus (MG1) as a boost. The use of an oncolytic rhabdovirus encoding a tumor antigen elicits a robust anti-cancer immune response and extends survival in murine models of cancer. Given the prevalence of pre-existing immunity to Ad5 globally, we explored the potential use of DEC205-targeted antibodies as an alternative agent to prime antigen-specific responses ahead of boosting with an oncolytic rhabdovirus expressing the same antigen. We found that a prime-boost vaccination strategy, consisting of an anti-DEC205 antibody fused to the model antigen ovalbumin (OVA) as a prime and oncolytic rhabdovirus-OVA as a boost, led to the formation of a robust antigen-specific immune response and improved survival in a B16-OVA tumor model. Overall, our study shows that anti-DEC205 antibodies fused to cancer antigens are effective to prime oncolytic rhabdovirus-boosted cancer antigen responses and may provide an alternative for patients with pre-existing immunity to Ad5 in humans.