Overcoming resistance to anti-PD immunotherapy in a syngeneic mouse lung cancer model using locoregional virotherapy

Oncolytic viruses in lung cancer treatment: a review article

Lung cancer has a high morbidity rate worldwide due to its resistance to therapy. So new treatment options are needed to improve the outcomes of lung cancer treatment. This study aimed to evaluate the effectiveness of oncolytic viruses (OVs) as a new type of cancer treatment. In this study, 158 articles from PubMed and Scopus from 1994 to 2022 were reviewed on the effectiveness of OVs in the treatment of lung cancer. The oncolytic properties of eight categories of OVs and their interactions with treatment options were investigated. OVs can be applied as a promising immunotherapy option, as they are reproduced selectively in different types of cancer cells, cause tumor cell lysis and trigger efficient immune responses.

Coxsackievirus A11 is an immunostimulatory oncolytic virus that induces complete tumor regression in a human non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. Innovative treatment is required to improve overall survival rates for advanced NSCLC. Oncolytic virotherapy using enteroviruses has emerged as a promising anticancer strategy. To identify a novel, potent virotherapy with an improved safety profile, we assessed the oncolytic activity of 28 enteroviral strains and focused on coxsackievirus A11 (CVA11). CVA11 infection caused extensive oncolytic activity in all three of the examined human NSCLC cell lines, with high intercellular adhesion molecule-1 (ICAM-1) expression associated with greater CVA11-induced cytotoxicity. In vitro inhibition analysis using a pan-caspase inhibitor and western blot detection of cleaved poly (ADP-ribose) polymerase (PARP) indicated that apoptosis partly contributed to CVA11-driven cytotoxicity. CVA11 infection-induced immunogenic cell death in vitro was strongly suggested by substantial calreticulin expression and release of high mobility group box-1 protein (HMGB1). Moreover, in vivo treatment of human NSCLC xenografts with intratumoral CVA11 injection caused complete tumor regression in all treated mice, without significant weight loss. Our findings indicate that novel oncolytic virotherapy utilizing CVA11 may be less toxic and more effective than current treatments for human NSCLC, thus warranting further investigation in clinical trial settings, especially in combination with immunotherapy.

Cell adhesion molecules and immunotherapy in advanced non-small cell lung cancer: Current process and potential application

Advanced non-small cell lung cancer (NSCLC) is a severe disease and still has high mortality rate after conventional treatment (e.g., surgical resection, chemotherapy, radiotherapy and targeted therapy). In NSCLC patients, cancer cells can induce immunosuppression, growth and metastasis by modulating cell adhesion molecules of both cancer cells and immune cells. Therefore, immunotherapy is increasingly concerned due to its promising anti-tumor effect and broader indication, which targets cell adhesion molecules to reverse the process. Among these therapies, immune checkpoint inhibitors (mainly anti-PD-(L)1 and anti-CTLA-4) are most successful and have been adapted as first or second line therapy in advanced NSCLC. However, drug resistance and immune-related adverse reactions restrict its further application. Further understanding of mechanism, adequate biomarkers and novel therapies are necessary to improve therapeutic effect and alleviate adverse effect.

Resistance to immunotherapy in human malignancies: Mechanisms, research progresses, challenges, and opportunities

Despite remarkable advances in different types of cancer therapies, an effective therapeutic strategy is still a major and significant challenge. One of the most promising approaches in this regard is immunotherapy, which takes advantage of the patients' immune system; however, the many mechanisms that cancerous cells harbor to extend their survival make it impossible to gain perfect eradication of tumors. The response rate to cancer immunotherapies, especially checkpoint inhibitors and adoptive T cell therapy, substantially differs in various cancer types with the highest rates in advanced melanoma and non-small cell lung cancer. Indeed, the lack of response in many tumors indicates primary resistance that can originate from either tumor cells (intrinsic) or tumor microenvironment (extrinsic). On the other hand, some tumors show an initial response to immunotherapy followed by relapse in few months (acquired resistance). Understanding the underlying molecular mechanisms of immunotherapy resistance makes it possible to develop effective strategies to overcome this hurdle and boost therapy outcomes. In this review, we take a look at immunotherapy strategies and go through a number of primary and acquired resistance mechanisms. Also, we present various ongoing methods to overcoming resistance and introduce some promising fields to improve the outcome of immunotherapy in patients affected with cancer.

Ex vivo dendritic cell-based (DC) vaccine pulsed with a low dose of liposomal antigen and CpG-ODN improved PD-1 blockade immunotherapy

Lack of pre-existing tumor infiltrated T cells resulting in resistance to programmed cell death protein 1 (PD-1) blockade therapies can be solved by combining with anti-cancer vaccines and CpG-ODN in increasing T cell expansion and infiltration. Therefore, we prepared an ex vivo dendritic cell-based (DC) vaccine pulsed with a low dose of either liposomal or non-liposomal gp100 antigen (2.8 µg) plus CpG-ODN (800 ng) formulations and evaluated its anti-tumor activity in combination with anti-PD-1 therapy. Our results showed a combination of liposomal peptide plus CpG-ODN pulsed DC with anti-PD-1 antibody was more efficacious, as evidenced by a significant increase in T_eff/T_reg TILs with a marked fourfold elevation of IFN-γ expression level in the tumor site of treated mice which reversed resistance to PD-1 blockade in a CD8 T cell-dependent manner. Furthermore, this combination also led to a remarkable tumor remission and prolonged survival rate in melanoma-bearing mice compared to non-liposomal peptide plus CpG-ODN or single-treated liposomal peptide formulations. Our results provide essential insights to devise combining regimens to improve the efficacy of immune checkpoint blockers even by a low dose of peptide and CpG-ODN.

Dual but not single PD-1 or TIM-3 blockade enhances oncolytic virotherapy in refractory lung cancer

Background

Programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade therapy fails in the majority of patients with cancer. Oncolytic viruses represent a new class of therapeutic agents, yet the therapeutic efficacy is still disappointing. Moreover, intratumoral injection of viruses is the main approach and preclinical studies mainly employ syngeneic or xenograft models.

Methods

Use an endogenous mouse lung cancer model that faithfully recapitulates human lung cancer, and various in vivo, ex vivo and in vitro assays, to investigate the efficacy, mechanism of action and resistance of systemically administered oncolytic vaccinia virus (oVV), immunotherapy and their combination, to find an effective therapy for refractory lung cancer.

Results

Resembling human lung cancers, the majority of which are largely resistant to PD-1/PD-L1 blockade and with decreased PD-L1 expression and T-cell activation by our analysis, urethane-induced endogenous lung tumors in mice show reduced PD-L1 expression, low tumor-infiltrating lymphocytes and innate resistance to PD-1/PD-L1 blockade. Intravenous administration of oVV has efficacy and synergizes with simultaneous but not single blockade of PD-1 and T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) in this cancer model. Besides direct tumor cell killing, oVV induces T-cell lung recruitment, tumor infiltration, along with expression of PD-1 and TIM-3 on T cells and PD-1 and TIM-3 ligands on tumor cells and tumor-associated immune cells. Blockade of PD-1 or TIM-3 also causes their mutual induction on T cells.

Conclusions

While systemic administration of oVV shows efficacy in lung cancer by killing tumor cells directly and recruiting and activating T cells for indirect tumor killing, its induction of PD-1 and TIM-3 on T cells and PD-1 and TIM-3 ligands on tumors and tumor-associated immune cells as well as mutual induction of PD-1 or TIM-3 on T cells by their blockade restricts the efficacy of oVV or its combination with single PD-1 or TIM-3 blockade. The triple combination therapy is more effective for refractory lung cancer, and possibly other cold cancers as well.

Vaccination with dendritic cells pulsed ex vivo with gp100 peptide-decorated liposomes enhances the efficacy of anti PD-1 therapy in a mouse model of melanoma

BACKGROUND

Targeting antigens to dendritic cells (DCs) via nanoparticles is a powerful strategy which improves the efficacy of ex vivo antigen-pulsed DC vaccines.

METHODS

In this study, liposomes were first decorated with gp100_25-33 self-antigen and then characterized. Then, DCs were pulsed ex vivo with liposomal gp100 and injected subcutaneously in mice bearing B16F10 established melanoma tumors in combination with anti-PD-1 therapy.

RESULTS

Treatment with liposomal pulsed DC vaccine elicited the strongest anticancer immunity and enhanced intratumoral immune responses based on infiltration of gp100-specific CD4+ and CD8+ T cells to the tumor leading to significant tumor growth regression and prolonged survival rate. Treatment with liposomal pulsed DC vaccine also markedly enhanced specific cytotoxic T lymphocytes (CTL) responses with a significant higher titer of IFN-γ in the spleen. Moreover, a significant increase of PD-1 expressing CD8+ tumor infiltrating lymphocytes (TILs) was detected in tumors.

CONCLUSION

Our results demonstrate an optimum dose of liposomal gp100 significantly increases the efficacy of anti-PD-1 therapy in mice and might be an effective strategy to overcome resistance to anti-PD-1 therapy.

In Situ Therapeutic Cancer Vaccination with an Oncolytic Virus Expressing Membrane-Tethered IL-2

Successful in situ therapeutic vaccination would allow locally delivered oncolytic virus (OV) to exert systemic immunologic effects on metastases and improve survival. We have utilized bilateral flank tumor models to determine the most efficacious regimens of in situ vaccination. Intratumoral injection with membrane-tethered interleukin -2-armed OV (vvDD-mIL2) plus a Toll-like receptor 9 ligand (CpG) yielded systemic immunization and decreased tumor growth in a contralateral, noninjected tumor. Our main aims were to study the tumor immune microenvironment (TME) after vaccination and identify additional immune adjuvants that may improve the systemic tumor-specific immunity. Immunological profiles in the spleen showed an increased CD8+ T cell/regulatory T cell (Treg) ratio and increased CD11c+ cells after dual injection in one flank tumor. Concurrently, there was increased infiltration of tumor necrosis factor alpha (TNF-α)+CD8+ T cells and interferon gamma (IFN-γ)+CD4+ T cells and reduced CTLA-4+PD-1+CD8+ T cells in the contralateral, noninjected tumor. The anti-tumoral activity depended on CD8+ T cells and IFN-γ, but not CD4+ T cells. Based on the negative immune components still existing in the untreated tumors, we investigated additional adjuvants: clodronate liposome-mediated depletion of macrophages plus anti-PD-1 therapy. This regimen dramatically reduced the tumor burden in the noninjected tumor and increased median survival by 87%, suggesting that inhibition/elimination of suppressive components in the tumor microenvironment (TME) can improve therapeutic outcomes. This study emphasizes the importance of immune profiling to design rational, combined immunotherapy regimens ultimately to impact patient survival.

Cancer inhibition mechanism of lung cancer mouse model based on dye trace method

To minimize the incidence and mortality of cancer, dye trace method was used to explore the mechanism of drug inhibition. 60 mice were selected as the research objects and randomly divided into five groups: model group, shikonin group, aconitine group, notoginsenoside R1 group, and compound group. When establishing the model, begin to administrate the medicine by gavage. The permeability of lung barrier was measured, and H.E staining, immunohistochemical staining, and Western blot test were carried out. The results showed that the mice in model group had decreased autonomic activity, increased permeability of the lung barrier, white nodules on the lung tissue, decreased protein expression related to cell proliferation and differentiation, and decreased protein expression associated with cell proliferation and differentiation, increased expression of related proteins in cancer stem cells, and low level of cell-linked communication. And the incidence of lung cancer in the model group mice was 100%. The histopathological changes in mice were improved to varying degrees after the intervention of the three drugs. Especially in the compound group, the incidence of lung cancer decreased to 8.3%. This study demonstrated that the combination of shikonin, aconitine and notoginsenoside R1 had a good anti-cancer effect, which provided a theoretical basis for clinical research.

Treatment options after first-line immunotherapy in metastatic NSCLC

Introduction: The recent approvals of checkpoint inhibitors as single agents or in combination with chemotherapy with programmed death ligand 1 expression of < or ≥1% have challenged clinicians when it is time to begin a metastatic lung cancer patient in second-line therapy. The advantages given by immunotherapy over conventional chemotherapy such as improved overall survival and a better toxicity profile make the second-line clinical scenario more difficult for a patient who faces a likely inferior regimen as well as toxicity which may significantly impact the quality of life.Areas covered: Options given today by the National Comprehensive Cancer Network are very limited, and essentially, we go back to conventional cytotoxic agents alone or in combination with biological agents if possible. In this article, we discuss the actual treatment available for this difficult scenario and some of the ongoing trials which aim to address this dilemma.Expert commentary: This is an unmet need in lung cancer management; we need a better understanding of the mechanism of resistance to immunotherapy so we can target them once the patient moves to second-line treatment.

Recombinant Adenovirus Expressing a Soluble Fusion Protein PD-1/CD137L Subverts the Suppression of CD8+ T Cells in HCC

Oncolytic viruses are an excellent platform for developing effective strategies in cancer immunotherapy. Several challenges remain in the use of viro-immunotherapy for cancer, such as the lack of costimulatory signals and negative regulation of immune checkpoints. In this study, we designed a novel adenovirus expressing a soluble fusion protein, programmed cell death protein 1 (PD-1)/CD137L, which contains the extracellular domains of PD-1 and CD137L at each terminus (Ad5-PC). Ad5-PC preserved the costimulatory activity of CD137L and facilitated the persistence of activated CD8⁺ T cells. Ad5-PC induced strikingly increased antitumor activity in both ascitic and subcutaneous hepatocellular carcinoma (HCC) tumor models, with 70% and 60% long-term cure rates, respectively. The improved antitumor effect of Ad5-PC was attributed to the sustained high-level lymphocyte activation and interferon (IFN)-γ production in the tumor microenvironment, and was essentially dependent on CD8⁺ T cells rather than natural killer (NK) cells. Moreover, Ad5-huPC-expressing human soluble PD-1/CD137L fusion protein was effective in suppressing tumor growth and improving survival in a humanized mouse model. We confirmed that Ad5-PC induced tumor-specific and systematic protection against tumor rechallenges at both in situ and distant sites. Thus, Ad5-PC harnesses several distinct functions to efficiently overcome several major hurdles of viro-immunotherapy.

Immunotherapy for non-small cell lung cancers: biomarkers for predicting responses and strategies to overcome resistance

Recent breakthroughs in targeted therapy and immunotherapy have revolutionized the treatment of lung cancer, the leading cause of cancer-related deaths in the United States and worldwide. Here we provide an overview of recent progress in immune checkpoint blockade therapy for treatment of non-small cell lung cancer (NSCLC), and discuss biomarkers associated with the treatment responses, mechanisms underlying resistance and strategies to overcome resistance. The success of immune checkpoint blockade therapies is driven by immunogenicity of tumor cells, which is associated with mutation burden and neoantigen burden in cancers. Lymphocyte infiltration in cancer tissues and interferon-γ-induced PD-L1 expression in tumor microenvironments may serve as surrogate biomarkers for adaptive immune resistance and likelihood of responses to immune checkpoint blockade therapy. In contrast, weak immunogenicity of, and/or impaired antigen presentation in, tumor cells are primary causes of resistance to these therapies. Thus, approaches that increase immunogenicity of cancer cells and/or enhance immune cell recruitment to cancer sites will likely overcome resistance to immunotherapy.

Superagonist IL-15-Armed Oncolytic Virus Elicits Potent Antitumor Immunity and Therapy That Are Enhanced with PD-1 Blockade

Oncolytic immunotherapy is a promising novel therapeutic for cancer, and further preclinical studies may maximize its therapeutic efficacy. In this study, we construct a novel oncolytic vaccinia virus (VV) expressing a superagoinst IL-15, a fusion protein of IL-15 and IL-15Ralpha. This virus, named vvDD-IL15-Rα, possesses similar replication efficiency as the parental virus vvDD yet leads to significantly more regression of the disease and extends the survival of mice bearing MC38 colon or ID8 ovarian cancer. This novel virus elicits potent adaptive antitumor immunity as shown by ELISPOT assays for interferon-gamma-secreting CD8+ T cells and by the rejection of tumor implants upon re-challenge in the mice, which were previously cured by vvDD-IL15-Rα treatment. In vivo cell depletion assays with antibodies showed that this antitumor activity is highly dependent on CD8+ T cells but much less so on CD4+ T cells and NK cells. Finally, the combination of the oncolytic immunotherapy with anti-PD-1 antibody dramatically improves the therapeutic outcome compared to either anti-PD-1 alone or vvDD-IL15-Rα alone. These results demonstrate that the IL-15-IL-15Rα fusion protein-expressing OV elicits potent antitumor immunity, and rational combination with PD-1 blockade leads to dramatic tumor regression and prolongs the survival of mice bearing colon or ovarian cancers.

Trial Watch: Oncolytic viro-immunotherapy of hematologic and solid tumors

Oncolytic viruses selectively target and kill cancer cells in an immunogenic fashion, thus supporting the establishment of therapeutically relevant tumor-specific immune responses. In 2015, the US Food and Drug Administration (FDA) approved the oncolytic herpes simplex virus T-VEC for use in advanced melanoma patients. Since then, a plethora of trials has been initiated to assess the safety and efficacy of multiple oncolytic viruses in patients affected with various malignancies. Here, we summarize recent preclinical and clinical progress in the field of oncolytic virotherapy.