An engineered oncolytic virus expressing PD-L1 inhibitors activates tumor neoantigen-specific T cell responses

Formulation-optimized oncolytic viruses: Advancing systemic delivery and immune amplification

Cancer is a major global public health challenge. Traditional treatments such as surgery, radiotherapy, and chemotherapy often show limited efficacy, minimal improvements in survival rates, and high recurrence risks. With limited therapeutic options for solid tumors, tumor immunotherapy, which harness the body's immune system, has gained significant attention. Oncolytic viruses (OVs) selectively infect and destroy tumor cells, induce immunogenic cell death (ICD) and stimulate antitumor immune responses. However, current OVs therapies, which are predominantly administered via intratumoral injection, have numerous limitations, including the need for guidance, suboptimal viral spread, extracellular matrix barriers, and immune clearance. These challenges hinder repeated dosing effectiveness and restrict its clinical applicability. Although genetic engineering has improved the tumor selectivity and immune activation of OVs, significant delivery challenges remain. Recently, optimizing pharmaceutical formulations to enhance tumor targeting and viral accumulation has emerged as a key approach to improving OV therapy and expanding clinical applicability. This review highlights the critical role of pharmaceutical formulations in biologics and outlines recent advances in OVs formulations. Specifically, we discuss strategies aimed at enhancing tumor targeting, reducing adverse effects, and promoting antitumor immunity. These strategies significantly enhance OV therapeutic potential and inform novel delivery systems for clinical translation.

Potential shared neoantigens from pan-cancer transcript isoforms

Isoform switching in cancer is a prevalent phenomenon with significant implications for immunotherapy, as actionable neoantigens derived from these cancer-specific events would be applicable to broad categories of patients, reducing the necessity for personalized treatments. By integrating five large-scale transcriptomic datasets comprising over 19,500 samples across 29 cancer and 54 normal tissue types, we identified cancer-associated isoform switching events common to multiple cancer types, several of which involve genes with established mechanistic roles in oncogenesis. The presence of neoantigen-containing peptides derived from these transcripts was confirmed in broad cancer and normal tissue proteome datasets and the binding affinity of predicted neoantigens to the human leukocyte antigen (HLA) complex via molecular dynamics simulations. The study presents strong evidence that isoform switching in cancer is a significant source of actionable neoantigens that have the capability to trigger an immune response. These findings suggest that isoform switching events could potentially be leveraged for broad immunotherapeutic strategies across various cancer types.

Siglec-15 antibody-GM-CSF chimera suppresses tumor progression via reprogramming tumor-associated macrophages

BACKGROUND

Sialic acid-binding immunoglobulin-like lectin (Siglec)-15-expressing tumor-associated macrophages (TAMs) drive immunosuppression in the tumor microenvironment (TME), promoting CD8+ T cell exhaustion and limiting immunotherapy efficacy. Both blockade of immune checkpoint molecule Siglec-15 and promotion of granulocyte-macrophage colony-stimulating factor (GM-CSF) have been respectively employed in anticancer immunotherapy.

METHODS

Murine CT26 or MC38 cancer cells were used to establish subcutaneous tumor models in BALB/c or C57BL/6 mice. Tumors were treated with anti-Siglec-15 antibody-GM-CSF chimera (anti-S15×GM CSF) or anti-Siglec-15 antibody via intraperitoneal injection. The TME was analyzed by flow cytometry and ELISA for immune cell infiltration and cytokine levels. Biodistribution and half-life of anti-S15×GM CSF were assessed by intravenous injection in tumor-bearing mice, with GM-CSF levels measured by ELISA. Macrophage reprogramming and antigen presentation were evaluated using bone marrow-derived macrophages and human peripheral blood mononuclear cell-derived macrophages treated with anti-S15×GM CSF, followed by flow cytometry and immunofluorescence assays.

RESULTS

Here we report that anti-S15×GM CSF displays superior function to suppress the progression of Siglec-15-overexpressing MC38 colon cancer engrafted in mice compared to anti-Siglec-15 antibody or GM-CSF alone. Different from the injected GM-CSF which is distributed broadly in various organs and tissues of mouse, the injected anti-S15×GM CSF is preferentially accumulated in Siglec-15-positive tumor cells and TAMs. Anti-S15×GM CSF not only extends the half-life of GM-CSF in vivo, but also reduces the off-target effect of GM-CSF through TAM-specific delivery. In addition to Siglec-15 blockade, anti-S15×GM CSF effectively reprograms immunosuppressive TAMs to a proinflammatory phenotype, enhancing antigen presentation by macrophages to activate T cells.

CONCLUSIONS

In summary, our results reveal that anti-S15×GM CSF may serve as an effective therapeutic approach for solid tumors.

Generalization of neoantigen-based tumor vaccine by delivering peptide-MHC complex via oncolytic virus

Neoantigen vaccine is a promising breakthrough in tumor immunotherapy. However, the application of this highly personalized strategy in the treatment of solid tumors is hindered by several obstacles, including very costly and time-consuming preparation steps, uncertainty in prediction algorithms and tumor heterogeneity. Universalization of neoantigen vaccine is an ideal yet currently unattainable solution to such limitations. To overcome these limitations, we engineered oncolytic viruses co-expressing neoantigens and neoantigen-binding major histocompatibility complex (MHC) molecules to force ectopic delivery of peptide-MHC ligands to T cell receptors (TCRs), enabling specific targeting by neoantigen vaccine-primed host immunity. When integrated with neoantigen vaccination, the engineered viruses exhibited potent cytolytic activity in a variety of tumor models irrespective of the neoantigen expression profiles, eliciting robust systemic antitumor immunity to reject tumor rechallenge and inhibit abscopal tumor growth with a favorable safety profile. Thus, this study provides a powerful approach to enhance the universality and efficacy of neoantigen vaccines, meeting the urgent need for universal neoantigen vaccines in the clinic to facilitate the further development of tumor immunotherapy.

Research progress and development potential of oncolytic vaccinia virus

ABSTRACT

Oncolytic virotherapy is a promising therapeutic approach treating tumors, where oncolytic viruses (OVs) can selectively infect and lyse tumor cells through replication, while also triggering long-lasting anti-tumor immune responses. Vaccinia virus (VV) has emerged as a leading candidate for use as an OV due to its broad cytophilicity and robust capacity to express exogenous genes. Consequently, oncolytic vaccinia virus (OVV) has entered clinical trials. This review provides an overview of the key strategies used in the development of OVV, summarizes the findings from clinical trials, and addresses the challenges that must be overcome in the advancement of OVV-based therapies. Furthermore, it explores potential future strategies for enhancing the development and clinical application of OVV, intending to improve tumor treatment outcomes. The review aims to facilitate the further development and clinical adoption of OVV, thereby advancing tumor therapies.

Viral expression of NE/PPE enhances anti-colorectal cancer efficacy of oncolytic adenovirus by promoting TAM M1 polarization to reverse insufficient effector memory/effector CD8+ T cell infiltration

BACKGROUND

Oncolytic adenoviruses are among the most widely utilized oncolytic viruses due to their notable anti-tumor and gene expression capabilities, and modification of ADVs to create armed adenoviruses remains a popular research direction. Nonetheless, immune suppression triggered by ADV and targeted enhancements based on this limitation have been relatively unexplored.

METHODS

Flow cytometry was employed to assess immune infiltration in the tumor microenvironment following ADV therapy. Targeted novel recombinant oncolytic viruses, ADVNE and ADVPPE, were designed, and their antitumor efficacy, safety, and ability to reshape immune infiltration were evaluated in both subcutaneous tumor models in mice and in vitro experiments. Immune cell depletion assays confirmed the critical role of macrophages. The impact of HMGB1 on macrophage polarization was investigated using shRNA, qRT-PCR, ELISA, and flow cytometry. Furthermore, the importance of TLR4 and its downstream pathways was validated through immunoprecipitation, Western blotting, homozygous knockout mice, and TLR4 inhibitors.

RESULTS

We demonstrated that ADV limits the infiltration of effector memory/effector CD8 + T cells (TEM/TE) within the tumor microenvironment. To address this, we leveraged the strong capacity of NE or PPE to recruit TEM/TE by constructing novel recombinant oncolytic adenoviruses, ADVNE or ADVPPE, armed with NE or PPE. These recombinant viruses induce pyroptosis in colorectal cancer cells accompanied by the release of HMGB1. HMGB1 binds to TLR4 on the surface of macrophages, activating the MyD88-NFκB-NLRP3 (ASC) pathway and promoting M1 polarization of TAMs, thereby increasing TEM/TE cell infiltration and enhancing antitumor efficacy.

CONCLUSIONS

In summary, this study presents the development of the novel oncolytic adenoviruses ADVNE and ADVPPE with enhanced anti-tumor efficacy and provides an in-depth exploration of their specific anti-tumor mechanisms. These findings indicate promising clinical therapeutic prospects and offer new insights for advancing oncolytic adenovirus therapies.

Electroacupuncture Modulates Programmed Cell Death 1 Ligand 1 on Peripheral and Central Nervous Systems in a Mouse Fibromyalgia Pain Model

Background: Fibromyalgia, a chronic condition that causes long-lasting pain over several months, is a global medical issue with both personal and societal implications. It is one of the hardest types of pain to heal, given the lack of objective parameters for diagnosis and progression evaluation. The main symptoms of fibromyalgia are long-lasting widespread pain alongside with anxiety, fatigue, sleep disorders, cognitive dysfunction, and obesity. Programmed cell death 1 ligand 1 (PD-L1) has been used as a target in cancer immunotherapy. It can inhibit acute and chronic pain by suppressing nociceptive neuron activity via PD-1 receptors. Methods: The current study aimed to investigate the role of PD-L1/PD1 in a mouse fibromyalgia pain model. Mice were exposed to intermittent cold stress (ICS) to produce a murine fibromyalgia model characterized using von Frey and Hargreaves tests. Results: The ICS-induced mice fibromyalgia pain model showed mechanical (2.26 ± 0.18 g) and thermal (4.36 ± 0.31 s) hyperalgesia. Nociceptive responses could be relieved with electroacupuncture, intracerebral PD-L1 injection, or Trpv1 deletion. We also identified a lower PD-1 level in the dorsal root ganglion, spinal cord, thalamus, and somatosensory cortex. In contrast, levels of pain-related kinases increased after fibromyalgia induction, an effect which could be reversed by EA, PD-L1, or Trpv1 deletion. Conclusions: Our findings shed light on the contribution of PD-L1/PD1 to EA and fibromyalgia pain, indicating its potential as a treatment target for fibromyalgia.

Tertiary lymphoid structures and cancer immunotherapy: From bench to bedside

Tertiary lymphoid structures (TLSs) are organized ectopic lymphoid aggregates within the tumor microenvironment that serve as crucial sites for the development of adaptive antitumor cellular and humoral immunity. TLSs have been consistently documented in numerous cancer types, correlating with improved prognosis and enhanced responses to immunotherapy, especially immune-checkpoint blockade (ICB). Given the potential role of TLSs as predictive biomarkers for the efficacy of ICB in cancer patients, the therapeutic manipulation of TLSs is gaining significant attention as a promising avenue for cancer treatment. Herein, we comprehensively review the composition, definition, and detection methods of TLSs in humans. We also discuss the contributions of TLSs to antitumor immunity, their prognostic value in cancer patients, and their association with therapeutic response to ICB-based immunotherapy. Finally, we present preclinical data supporting the potential of therapeutically manipulating TLSs as a promising approach for innovative cancer immunotherapy.

Injecting hope: the potential of intratumoral immunotherapy for locally advanced and metastatic cancer

Despite enormous progress, advanced cancers are still one of the most serious medical problems in current society. Although various agents and therapeutic strategies with anticancer activity are known and used, they often fail to achieve satisfactory long-term patient outcomes and survival. Recently, immunotherapy has shown success in patients by harnessing important interactions between the immune system and cancer. However, many of these therapies lead to frequent side effects when administered systemically, prompting treatment modifications or discontinuation or, in severe cases, fatalities. New therapeutic approaches like intratumoral immunotherapy, characterized by reduced side effects, cost, and systemic toxicity, offer promising prospects for future applications in clinical oncology. In the context of locally advanced or metastatic cancer, combining diverse immunotherapeutic and other treatment strategies targeting multiple cancer hallmarks appears crucial. Such combination therapies hold promise for improving patient outcomes and survival and for promoting a sustained systemic response. This review aims to provide a current overview of immunotherapeutic approaches, specifically focusing on the intratumoral administration of drugs in patients with locally advanced and metastatic cancers. It also explores the integration of intratumoral administration with other modalities to maximize therapeutic response. Additionally, the review summarizes recent advances in intratumoral immunotherapy and discusses novel therapeutic approaches, outlining future directions in the field.

A novel oncolytic Vaccinia virus armed with IL-12 augments antitumor immune responses leading to durable regression in murine models of lung cancer

Oncolytic vaccinia viruses (VVs) are potent stimulators of the immune system and induce immune-mediated tumor clearance and long-term surveillance against tumor recurrence. As such they are ideal treatment modalities for solid tumors including lung cancer. Here, we investigated the use of VVL-m12, a next-generation, genetically modified, interleukin-12 (IL-12)-armed VV, as a new therapeutic strategy to treat murine models of lung cancer and as a mechanism of increasing lung cancer sensitivity to antibody against programmed cell death protein 1 (α-PD1) therapy. The cytotoxicity and replication of VVL-m12, VVL-h12 and control VVs were assessed in lung cancer cell lines. Subcutaneous lung cancer mouse models were established to investigate the anti-tumor activity of the viruses after intratumoral delivery in an immunocompetent disease model. Synergy with α-PD1 or a VV armed with soluble PD-1 (VV-sPD1) was investigated and functional mechanisms behind efficacy probed. Tumor-targeted VVL-m12 replicated to high levels, was cytotoxic in lung cancer cell lines. VVL-m12 demonstrated superior antitumor efficacy in subcutaneous lung cancer models compared with other VVs examined. Importantly, rational combination of VVL-m12 and PD-1 blockade worked synergistically to significantly enhance survival of animals and safely cured lung cancer with no evidence of recurrence. VVL-m12 therapy induced increased intratumoral infiltration of CD4+ and CD8+ T cells and was able to clear tumor at early time points via increased induction and infiltration of effector T cells and central memory T cells (TCM). In addition, VVL-m12 increased dendritic cell activation, induced polarization of M2 macrophages towards an M1 phenotype, and inhibited tumor angiogenesis in vivo. These results demonstrate that VVL-12 has strong potential as a safe and effective antitumor therapeutic for lung cancer. Importantly, VVL-12 can sensitize lung cancers to α-PD1 antibody therapy, and the combined regime creates a highly effective treatment option for patients.

GM-CSF and IL-21-armed oncolytic vaccinia virus significantly enhances anti-tumor activity and synergizes with anti-PD1 immunotherapy in pancreatic cancer

Pancreatic cancer is one of the most aggressive cancers and poses significant challenges to current therapies because of its complex immunosuppressive tumor microenvironment (TME). Oncolytic viruses armed with immunoregulatory molecules are promising strategies to overcome limited efficacy and target inaccessible and metastatic tumors. In this study, we constructed a tumor-selective vaccinia virus (VV) with deletions of the TK and A49 genes (VVLΔTKΔA49, VVL-DD) using CRISPR-Cas9-based homologous recombination. VVL-DD exhibited significant tumor selectivity in vitro and anti-tumor potency in vivo in a murine pancreatic cancer model. Then, VVL-DD was armed with an optimal combination of immunomodulatory molecules, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-21 (IL-21), to produce VVL-GL21. VVL-GL21 induced significant tumor regression after intratumoral and systemic administration. Moreover, VVL-GL21 increased the infiltration of dendritic cells (DCs), macrophages, and T cells; induced DC maturation; increased the transition from M2 to M1 macrophages; improved the formation of immune memory; prevented tumor recurrence; and effectively bolstered the immune response against tumors in multiple key immune compartments. Interestingly, mice bearing-pancreatic cancer tumors treated with VVL-GL21 showed anti-tumor immunity against lung and colon cancer tumors. Importantly, treatment with VVL-GL21 enhanced the responsiveness of tumors to the immune checkpoint inhibitor anti-PD1. Taken together, VVL-GL21 remodels the suppressive TME and has powerful anti-tumor activities as monotherapy or in combination with anti-PD1 by intratumoral or systemic delivery for the treatment of pancreatic cancer. VVL-GL21 could be used as a therapeutic cancer vaccine.

Advancing tumor vaccines: Overcoming TME challenges, delivery strategies, and biomaterial-based vaccine for enhanced immunotherapy

Tumor vaccines, as an immunotherapeutic approach, harness the body's immune cells to provoke antitumor responses, which have shown promising efficacy in clinical settings. However, the immunosuppressive tumor microenvironment (TME) and the ineffective vaccine delivery systems hinder the progression of many vaccines beyond phase II trials. This article begins with a comprehensive review of the complex interactions between tumor vaccines and TME, summarizing the current state of vaccine clinical research. Subsequently, we review recent advancements in targeted vaccine delivery systems and explore biomaterial-based tumor vaccines as a strategy to improve the efficacy of both delivery systems and treatment. Finally, we have presented our perspectives on tumor vaccine development, aiming to advance the field towards the creation of more effective tumor vaccines.

Oncolytic vaccinia virus armed with anti-CD47 nanobody elicit potent antitumor effects on multiple tumor models via enhancing innate and adoptive immunity

OBJECTIVE

Targeting CD47 for cancer immunotherapy has been studied in many clinical trials for the treatment of patients with advanced tumors. However, this therapeutic approach is often hampered by on-target side effects, physical barriers, and immunosuppressive tumor microenvironment (TME).

METHODS

To improve therapeutic efficacy while minimizing toxicities, we engineered an oncolytic vaccinia virus (OVV) encoding an anti-CD47 nanobody (OVV-αCD47nb). We demonstrated the specific binding activity of αCD47nb secreted from the virus-infected cells to CD47 and that both secreted αCD47nb and OVV-αCD47nb blocked the "don't eat me" signal of macrophages.

RESULTS

Intratumorally injected OVV-αCD47nb continuously releases the αCD47nb in tumor tissues, thereby conferring superior systemic activity against breast and colon tumor cells and prolonging survival compared with OVV control. Furthermore, treatment with OVV-αCD47nb also remodeled the TME, as shown by increased T cell infiltration, CD8+ T cell activation and tumor-associated macrophages polarization, significantly enhancing innate and adoptive immunity. Additionally, the inclusion of programmed cell death protein-1 inhibiting boosted the anticancer efficacy of OVV-αCD47nb and raised the full response rate in tumor-bearing animals.

CONCLUSION

Overall, our findings highlight the therapeutic potential of OVV-αCD47nb for breast and colon cancer, and demonstrate its ability to modulate the immune cell profiles within tumors. This has established a rationale for further exploring OVV-αCD47nb as a potential therapy in the clinic.

Triggering immunogenic death of cancer cells by nanoparticles overcomes immunotherapy resistance

Immunotherapy resistance poses a significant challenge in oncology, necessitating novel strategies to enhance the therapeutic efficacy. Immunogenic cell death (ICD), including necroptosis, pyroptosis and ferroptosis, triggers the release of tumor-associated antigens and numerous bioactive molecules. This release can potentiate a host immune response, thereby overcoming resistance to immunotherapy. Nanoparticles (NPs) with their biocompatible and immunomodulatory properties, are emerging as promising vehicles for the delivery of ICD-inducing agents and immune-stimulatory adjuvants to enhance immune cells tumoral infiltration and augment immunotherapy efficacy. This review explores the mechanisms underlying immunotherapy resistance, and offers an in-depth examination of ICD, including its principles and diverse modalities of cell death that contribute to it. We also provide a thorough overview of how NPs are being utilized to trigger ICD and bolster antitumor immunity. Lastly, we highlight the potential of NPs in combination with immunotherapy to revolutionize cancer treatment.

An oncolytic virus-T cell chimera for cancer immunotherapy

The efficacy of oncolytic adenoviruses (OAs) for cancer therapy has been limited by insufficient delivery to tumors after systemic injection and the propensity of OAs to induce the expression of immune checkpoints. To address these limitations, we use T cells to deliver OAs into tumors and engineer the OA to express a Cas9 system targeting the PDL1 gene encoding the immune checkpoint protein PD-L1. By cloaking OAs with cell membranes presenting T cell-specific antigens, we physically conjugated OAs onto T cell surfaces by antigen-receptor interaction. We tested the oncolytic virus-T cell chimera (ONCOTECH) via intravenous delivery in mouse cancer models, including models of melanoma, pancreatic adenocarcinoma, lung cancer and glioblastoma. In the melanoma model, the in vivo delivery of ONCOTECH resulted in a strong accumulation of OAs in tumor cells, where PD-L1 expression was reduced by 50% and the single administration of ONCOTECH enabled 80% survival over 70 days. Collectively, ONCOTECH represents a promising translational technology to combine virotherapy and cell therapy.

Oncolytic Vesicular Stomatitis Virus: Optimisation Strategies for Anti-Cancer Therapies

Oncolytic viruses (OVs) represent a targeted anti-cancer therapy approach due to their ability not only to selectively infect and destroy malignant cells but also to induce an immune response. Vesicular stomatitis virus (VSV) offers a promising platform due to its low prevalence and pathogenicity in humans, lack of pre-existing immunity, easily manipulated genome, rapid growth to high titers in a broad range of cell lines, and inability to integrate into the host genome. However, despite its many advantages, many unresolved problems remain: problematic production based on the reverse genetics system, oncological selectivity, and the overall effectiveness of VSV monotherapy. This review will discuss various attempts at viral genome modifications aimed at improving the oncolytic properties of VSV. These strategies include inhibition of viral genes, modification of genes responsible for targeting cancer cells over healthy ones, insertion of foreign genes for boosting immune response, and changing the order of viral and inserted foreign genes. In addition, possible ways to improve VSV-based anti-tumor therapy and achieve higher efficiency will be considered by evaluating the effectiveness of various delivery methods as well as discussing treatment options by combining VSV with other groups of anticancer drugs.

Cold and hot tumors: from molecular mechanisms to targeted therapy

Immunotherapy has made significant strides in cancer treatment, particularly through immune checkpoint blockade (ICB), which has shown notable clinical benefits across various tumor types. Despite the transformative impact of ICB treatment in cancer therapy, only a minority of patients exhibit a positive response to it. In patients with solid tumors, those who respond well to ICB treatment typically demonstrate an active immune profile referred to as the "hot" (immune-inflamed) phenotype. On the other hand, non-responsive patients may exhibit a distinct "cold" (immune-desert) phenotype, differing from the features of "hot" tumors. Additionally, there is a more nuanced "excluded" immune phenotype, positioned between the "cold" and "hot" categories, known as the immune "excluded" type. Effective differentiation between "cold" and "hot" tumors, and understanding tumor intrinsic factors, immune characteristics, TME, and external factors are critical for predicting tumor response and treatment results. It is widely accepted that ICB therapy exerts a more profound effect on "hot" tumors, with limited efficacy against "cold" or "altered" tumors, necessitating combinations with other therapeutic modalities to enhance immune cell infiltration into tumor tissue and convert "cold" or "altered" tumors into "hot" ones. Therefore, aligning with the traits of "cold" and "hot" tumors, this review systematically delineates the respective immune characteristics, influencing factors, and extensively discusses varied treatment approaches and drug targets based on "cold" and "hot" tumors to assess clinical efficacy.

A novel vesicular stomatitis virus armed with IL-2 mimic for oncolytic therapy

Oncolytic virus (OV) is increasingly being recognized as a novel vector in cancer immunotherapy. Increasing evidence suggests that OV has the ability to change the immune status of tumor microenvironment, so called transformation of 'cold' tumors into 'hot' tumors. The improved anti-tumor immunity can be induced by OV and further enhanced through the combination of various immunomodulators. The Neo-2/15 is a newly de novo synthesized cytokine that functions as both IL-2 and IL-15. However, it specifically lacks the binding site of IL-2 receptor α subunit (CD25), therefore unable to induce the Treg proliferation. In present study, a recombinant vesicular stomatitis virus expressing the Neo-2/15 (VSVM51R-Neo-2/15) was generated. Intratumoral delivery of VSVM51R-Neo-2/15 efficiently inhibited tumor growth in mice without causing the IL-2-related toxicity previously observed in clinic. Moreover, treatment with VSVM51R-Neo-2/15 increased the number of activated CD8+ T cells but not Treg cells in tumors. More tumor-bearing mice were survival with VSVM51R-Neo-2/15 treatment, and the surviving mice displayed enhanced protection against tumor cell rechallenge due to the induced anti-tumor immunity. In addition, combination therapy of OV and anti-PD-L1 immune checkpoint inhibitors further enhanced the anti-tumor immune response. These findings suggest that our novel VSVM51R-Neo-2/15 can effectively inhibit the tumor growth and enhance the sensitivity to immune checkpoint inhibitors, providing promising attempts for further clinical trials.

Effects of intratumoral microbiota on tumorigenesis, anti-tumor immunity, and microbe-based cancer therapy

Intratumoral microbiota (IM) has emerged as a significant component of the previously thought sterile tumor microenvironment (TME), exerting diverse functions in tumorigenesis and immune modulation. This review outlines the historical background, classification, and diversity of IM, elucidating its pivotal roles in oncogenicity, cancer development, and progression, alongside its influence on anti-tumor immunity. The signaling pathways through which IM impacts tumorigenesis and immunity, including reactive oxygen species (ROS), β-catenin, stimulator of interferon genes (STING), and other pathways [NF-κB, Toll-like receptor (TLR), complement, RhoA/ROCK, PKR-like ER kinase (PERK)], are discussed comprehensively. Furthermore, we briefly introduce the clinical implications of IM, emphasizing its potential as a target for novel cancer therapies, diagnostic biomarkers, and prognostic indicators. Notably, microbe-based therapeutic strategies such as fecal microbiome transplantation (FMT), probiotics regulation, bacteriotherapy, bacteriophage therapy, and oncolytic virotherapy are highlighted. These strategies hold promise for enhancing the efficacy of current cancer treatments and warrant further exploration in clinical settings.

Tertiary lymphoid structures in anticancer immunity

Tertiary lymphoid structures (TLS) are transient ectopic lymphoid aggregates where adaptive antitumour cellular and humoral responses can be elaborated. Initially described in non-small cell lung cancer as functional immune lymphoid structures associated with better clinical outcome, TLS have also been found in many other carcinomas, as well as melanomas and sarcomas, and associated with improved response to immunotherapy. The manipulation of TLS as a therapeutic strategy is now coming of age owing to the likely role of TLS in the improved survival of patients with cancer receiving immune checkpoint inhibitor treatment. TLS have also garnered considerable interest as a predictive biomarker of the response to antitumour therapies, including immune checkpoint blockade and, possibly, chemotherapy. However, several important questions still remain regarding the definition of TLS in terms of both their cellular composition and functions. Here, we summarize the current views on the composition of TLS at different stages of their development. We also discuss the role of B cells and T cells associated with TLS and their dialogue in mounting antibody and cellular antitumour responses, as well as some of the various mechanisms that negatively regulate antitumour activity of TLS. The prognostic value of TLS to the clinical outcome of patients with cancer and the relationship between TLS and the response to therapy are then addressed. Finally, we present some preclinical evidence that favours the idea that manipulating the formation and function of TLS could lead to a potent next-generation cancer immunotherapy.

oHSV2-mGM repolarizes TAMs and cooperates with αPD1 to reprogram the immune microenvironment of residual cancer after radiofrequency ablation

BACKGROUND

Due to the size and location of the tumor, incomplete radiofrequency ablation (iRFA) of the target tumor inhibits tumor immunity. In this study, a murine herpes simplex virus (oHSV2-mGM) armed with granulocyte-macrophage colony-stimulating factor (GM-CSF) was constructed to explore its effect on innate and adaptive immunity during iRFA, and the inhibitory effect of programmed cell death-1 (PD1) on tumor.

METHODS

We verified the polarization and activation of RAW264.7 cells mediated by oHSV2-mGM in vitro. Subsequently, we evaluated the efficacy of oHSV2-mGM alone and in combination with αPD1 in the treatment of residual tumors after iRFA in two mouse models. RNA-seq was used to characterize the changes of tumor microenvironment.

RESULTS

oHSV2-mGM lysate effectively stimulated RAW264.7 cells to polarize into M1 cells and activated M1 phenotypic function. In the macrophage clearance experiment, oHSV2-mGM activated the immune response of tumor in mice. The results in vivo showed that oHSV2-mGM showed better anti-tumor effect in several mouse tumor models. Finally, oHSV2-mGM combined with PD1 antibody can further enhance the anti-tumor effect of oHSV2-mGM and improve the complete remission rate of tumor in mice.

CONCLUSION

The application of oHSV2-mGM leads to the profound remodeling of the immune microenvironment of residual tumors. oHSV2-mGM also works in synergy with PD1 antibody to achieve complete remission of tumors that do not respond well to monotherapy at immune checkpoints. Our results support the feasibility of recombinant oncolytic virus in the treatment of residual tumors after iRFA, and propose a new strategy for oncolytic virus treatment of tumors.

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

Enhanced Anti-Tumor Response Elicited by a Novel Oncolytic Pseudorabies Virus Engineered with a PD-L1 Inhibitor

Oncolytic viruses combined with immunotherapy offer significant potential in tumor therapy. In this study, we engineered a further attenuated pseudorabies virus (PRV) vaccine strain that incorporates a PD-L1 inhibitor and demonstrated its promise as an oncolytic virus in tumor therapy. We first showed that the naturally attenuated PRV vaccine strain Bartha can efficiently infect tumor cells from multiple species, including humans, mice, and dogs in vitro. We then evaluated the safety and anti-tumor efficacy of this vaccine strain and its different single-gene deletion mutants using the B16-F10 melanoma mouse model. The TK deletion strain emerged as the optimal vector, and we inserted a PD-L1 inhibitor (iPD-L1) into it using CRISPR/Cas9 technology. Compared with the control, the recombinant PRV (rPRV-iPD-L1) exhibited more dramatic anti-tumor effects in the B16-F10 melanoma mouse model. Our study suggests that PRV can be developed not only as an oncolytic virus but also a powerful vector for expressing foreign genes to modulate the tumor microenvironment.

A GalNAc-modified CaCO3 nano-immunomodulator for targeted and responsive immunotherapy against orthotopic liver cancer

A nano-immunomodulator modified with N-acetylgalactosamine (GalNAc) on calcium carbonate (CaCO3) was prepared for targeted and responsive immunotherapy. And the immunologic adjuvant (CpG ODNs) and doxorubicin (DOX) were released to synergistically improve immune response for treating orthotopic liver cancer.

Enhancing cancer therapy: the integration of oncolytic virus therapy with diverse treatments

As one of the significant challenges to human health, cancer has long been a focal point in medical treatment. With ongoing advancements in the field of medicine, numerous methodologies for cancer therapy have emerged, among which oncolytic virus therapy has gained considerable attention. However, oncolytic viruses still exhibit limitations. Combining them with various therapies can further enhance the efficacy of cancer treatment, offering renewed hope for patients. In recent research, scientists have recognized the promising prospect of amalgamating oncolytic virus therapy with diverse treatments, potentially surmounting the restrictions of singular approaches. The central concept of this combined therapy revolves around leveraging oncolytic virus to incite localized tumor inflammation, augmenting the immune response for immunotherapeutic efficacy. Through this approach, the patient's immune system can better recognize and eliminate cancer cells, simultaneously reducing tumor evasion mechanisms against the immune system. This review delves deeply into the latest research progress concerning the integration of oncolytic virus with diverse treatments and its role in various types of cancer therapy. We aim to analyze the mechanisms, advantages, potential challenges, and future research directions of this combination therapy. By extensively exploring this field, we aim to instill renewed hope in the fight against cancer.

The Role of Natural Killer Cells in Oncolytic Virotherapy: Friends or Foes?

Oncolytic virotherapy (OVT) has emerged as a promising cancer immunotherapy, and is capable of potentiating other immunotherapies due to its capacity to increase tumor immunogenicity and to boost host antitumor immunity. Natural killer (NK) cells are a critical cellular component for mediating the antitumor response, but hold a mixed reputation for their role in mediating the therapeutic efficacy of OVT. This review will discuss the pros and cons of how NK cells impact OVT, and how to harness this knowledge for the development of effective strategies that could modulate NK cells to improve OVT-based therapeutic outcomes.

Immune landscape and response to oncolytic virus-based immunotherapy

Oncolytic virus (OV)-based immunotherapy has emerged as a promising strategy for cancer treatment, offering a unique potential to selectively target malignant cells while sparing normal tissues. However, the immunosuppressive nature of tumor microenvironment (TME) poses a substantial hurdle to the development of OVs as effective immunotherapeutic agents, as it restricts the activation and recruitment of immune cells. This review elucidates the potential of OV-based immunotherapy in modulating the immune landscape within the TME to overcome immune resistance and enhance antitumor immune responses. We examine the role of OVs in targeting specific immune cell populations, including dendritic cells, T cells, natural killer cells, and macrophages, and their ability to alter the TME by inhibiting angiogenesis and reducing tumor fibrosis. Additionally, we explore strategies to optimize OV-based drug delivery and improve the efficiency of OV-mediated immunotherapy. In conclusion, this review offers a concise and comprehensive synopsis of the current status and future prospects of OV-based immunotherapy, underscoring its remarkable potential as an effective immunotherapeutic agent for cancer treatment.

Fn-OMV potentiates ZBP1-mediated PANoptosis triggered by oncolytic HSV-1 to fuel antitumor immunity

Oncolytic viruses (OVs) show promise as a cancer treatment by selectively replicating in tumor cells and promoting antitumor immunity. However, the current immunogenicity induced by OVs for tumor treatment is relatively weak, necessitating a thorough investigation of the mechanisms underlying its induction of antitumor immunity. Here, we show that HSV-1-based OVs (oHSVs) trigger ZBP1-mediated PANoptosis (a unique innate immune inflammatory cell death modality), resulting in augmented antitumor immune effects. Mechanistically, oHSV enhances the expression of interferon-stimulated genes, leading to the accumulation of endogenous Z-RNA and subsequent activation of ZBP1. To further enhance the antitumor potential of oHSV, we conduct a screening and identify Fusobacterium nucleatum outer membrane vesicle (Fn-OMV) that can increase the expression of PANoptosis execution proteins. The combination of Fn-OMV and oHSV demonstrates potent antitumor immunogenicity. Taken together, our study provides a deeper understanding of oHSV-induced antitumor immunity, and demonstrates a promising strategy that combines oHSV with Fn-OMV.

The emerging tumor microbe microenvironment: From delineation to multidisciplinary approach-based interventions

Intratumoral microbiota has become research hotspots, and emerges as a non-negligent new component of tumor microenvironments (TME), due to its powerful influence on tumor initiation, metastasis, immunosurveillance and prognosis despite in low-biomass. The accumulations of microbes, and their related components and metabolites within tumor tissues, endow TME with additional pluralistic features which are distinct from the conventional one. Therefore, it's definitely necessary to comprehensively delineate the sophisticated landscapes of tumor microbe microenvironment, as well as their functions and related underlying mechanisms. Herein, in this review, we focused on the fields of tumor microbe microenvironment, including the heterogeneity of intratumor microbiota in different types of tumors, the controversial roles of intratumoral microbiota, the basic features of tumor microbe microenvironment (i.e., pathogen-associated molecular patterns (PAMPs), typical microbial metabolites, autophagy, inflammation, multi-faceted immunomodulation and chemoresistance), as well as the multidisciplinary approach-based intervention of tumor microbiome for cancer therapy by applying wild-type or engineered live microbes, microbiota metabolites, antibiotics, synthetic biology and rationally designed biomaterials. We hope our work will provide valuable insight to deeply understand the interplay of cancer-immune-microbial, and facilitate the development of microbes-based tumor-specific treatments.

Immune Cytolytic Activity and Strategies for Therapeutic Treatment

Intratumoral immune cytolytic activity (CYT), calculated as the geometric mean of granzyme-A (GZMA) and perforin-1 (PRF1) expression, has emerged as a critical factor in cancer immunotherapy, with significant implications for patient prognosis and treatment outcomes. Immune checkpoint pathways, the composition of the tumor microenvironment (TME), antigen presentation, and metabolic pathways regulate CYT. Here, we describe the various methods with which we can assess CYT. The detection and analysis of tumor-infiltrating lymphocytes (TILs) using flow cytometry or immunohistochemistry provide important information about immune cell populations within the TME. Gene expression profiling and spatial analysis techniques, such as multiplex immunofluorescence and imaging mass cytometry allow the study of CYT in the context of the TME. We discuss the significant clinical implications that CYT has, as its increased levels are associated with positive clinical outcomes and a favorable prognosis. Moreover, CYT can be used as a prognostic biomarker and aid in patient stratification. Altering CYT through the different methods targeting it, offers promising paths for improving treatment responses. Overall, understanding and modulating CYT is critical for improving cancer immunotherapy. Research into CYT and the factors that influence it has the potential to transform cancer treatment and improve patient outcomes.

Recent progress in combination therapy of oncolytic vaccinia virus

In recent years, oncolytic viruses have emerged as promising agents for treating various cancers. An oncolytic virus is a non-pathogenic virus that, due to genetic manipulation, tends to replicate in and cause lysis of cancerous cells while leaving healthy cells unaffected. Among these viruses, vaccinia virus is an attractive platform for use as an oncolytic platform due to its 190 Kb genome with a high capacity for encoding therapeutic payloads. Combining oncolytic VV therapy with other conventional cancer treatments has been shown to be synergistic and more effective than monotherapies. Additionally, OVV can be used as a vector to deliver therapeutic payloads, alone or in combination with other treatments, to increase overall efficacy. Here, we present a comprehensive analysis of preclinical and clinical studies that have evaluated the efficacy of oncolytic vaccinia viruses in cancer immunotherapy. We discuss the outcomes of these studies, including tumor regression rates, overall survival benefits, and long-term responses. Moreover, we provide insights into the challenges and limitations associated with oncolytic vaccinia virus- based therapies, including immune evasion mechanisms, potential toxicities, and the development of resistance.

Integrating innate and adaptive immunity in oncolytic virus therapy

Oncolytic viruses (OVs), viruses engineered to lyse tumor cells, work hand in hand with the immune response. While for decades the field isolated lytic capability and viral spread to increase response to virotherapy, there is now a wealth of research that demonstrates the importance of immunity in the OV mechanism of action. In this review, we will cover how OVs interact with the innate immune system to fully activate the adaptive immune system and yield exceptional tumor clearances as well as look forward at combination therapies which can improve clinical responses.

Arming oncolytic viruses with bispecific T cell engagers: The evolution and current status

Oncolytic viruses (OVs) are emerging as therapeutically relevant anticancer agents as contemporary immunotherapy gains traction. Furthermore, OVs are an ideal platform for genetic modification to express therapeutic transgenes. Bispecific T cell engagers (BiTEs) can redirect T cells to tumor cells, resulting in targeted cytotoxicity. BiTEs have demonstrated success in hematological cancers but are rarely used in solid tumors. The drawbacks of BiTEs, including inadequate delivery and on-target-off-tumor activity have limited their efficacy. Combining OVs with BiTEs is a prospective area to investigate. This combined strategy can benefit from the best qualities of both therapies while overcoming the limitations.

Roles of exosomes in immunotherapy for solid cancers

Although immunotherapy has made breakthrough progress, its efficacy in solid tumours remains unsatisfactory. Exosomes are the main type of extracellular vesicles that can deliver various intracellular molecules to adjacent or distant cells and organs, mediating various biological functions. Studies have found that exosomes can both activate the immune system and inhibit the immune system. The antigen and major histocompatibility complex (MHC) carried in exosomes make it possible to develop them as anticancer vaccines. Exosomes derived from blood, urine, saliva and cerebrospinal fluid can be used as ideal biomarkers in cancer diagnosis and prognosis. In recent years, exosome-based therapy has made great progress in the fields of drug transportation and immunotherapy. Here, we review the composition and sources of exosomes in the solid cancer immune microenvironment and further elaborate on the potential mechanisms and pathways by which exosomes influence immunotherapy for solid cancers. Moreover, we summarize the potential clinical application prospects of engineered exosomes and exosome vaccines in immunotherapy for solid cancers. Eventually, these findings may open up avenues for determining the potential of exosomes for diagnosis, treatment, and prognosis in solid cancer immunotherapy.

Oncolytic vaccinia virus and cancer immunotherapy

Oncolytic virotherapy (OVT) is a promising form of cancer treatment that uses genetically engineered viruses to replicate within cancer cells and trigger anti-tumor immune response. In addition to killing cancer cells, oncolytic viruses can also remodel the tumor microenvironment and stimulate a long-term anti-tumor immune response. Despite achieving positive results in cellular and organismal studies, there are currently only a few approved oncolytic viruses for clinical use. Vaccinia virus (VACV) has emerged as a potential candidate due to its ability to infect a wide range of cancer cells. This review discusses the mechanisms, benefits, and clinical trials of oncolytic VACVs. The safety and efficacy of different viral backbones are explored, as well as the effects of oncolytic VACVs on the tumor microenvironment. The potential combination of oncolytic VACVs with immunotherapy or traditional therapies is also highlighted. The review concludes by addressing prospects and challenges in the field of oncolytic VACVs, with the aim of promoting further research and application in cancer therapy.

Recent progress, perspectives, and issues of engineered PD-L1 regulation nano-system to better cure tumor: A review

Currently, immune checkpoint blockade (ICB) therapies that target the programmed cell death ligand-1 (PD-L1) have been used as revolutionary cancer treatments in the clinic. Apart from restoring the antitumor response of cytotoxic T cells by blocking the interaction between PD-L1 on tumor cells and programmed cell death-1 (PD-1) on T cells, PD-L1 proteins were also newly revealed to possess the capacity to accelerate DNA damage repair (DDR) and enhance tumor growth through multiple mechanisms, leading to the impaired efficacy of tumor therapies. Nevertheless, current free anti-PD-1/PD-L1 therapy still suffered from poor therapeutic outcomes in most solid tumors due to the non-selective tumor accumulation, ineludible severe cytotoxic effects, as well as the common occurrence of immune resistance. Recently, nanoparticles with efficient tumor-targeting capacity, tumor-responsive prosperity, and versatility for combination therapy were identified as new avenues for PD-L1 targeting cancer immunotherapies. In this review, we first summarized the multiple functions of PD-L1 protein in promoting tumor growth, accelerating DDR, as well as depressing immunotherapy efficacy. Following this, the effects and mechanisms of current clinically widespread tumor therapies on tumor PD-L1 expression were discussed. Then, we reviewed the recent advances in nanoparticles for anti-PD-L1 therapy via using PD-L1 antibodies, small interfering RNA (siRNA), microRNA (miRNA), clustered, regularly interspaced, short palindromic repeats (CRISPR), peptide, and small molecular drugs. At last, we discussed the challenges and perspectives to promote the clinical application of nanoparticles-based PD-L1-targeting therapy.

Development of Recombinant Oncolytic rVSV-mIL12-mGMCSF for Cancer Immunotherapy

Anti-cancer therapy based on oncolytic viruses (OVs) is a targeted approach that takes advantage of OVs' ability to selectively infect and replicate in tumor cells, activate the host immune response, and destroy malignant cells over healthy ones. Vesicular stomatitis virus (VSV) is known for its wide range of advantages: a lack of pre-existing immunity, a genome that is easily amenable to manipulation, and rapid growth to high titers in a broad range of cell lines, to name a few. VSV-induced tumor immunity can be enhanced by the delivery of immunostimulatory cytokines. The targeted cytokine delivery to tumors avoids the significant toxicity associated with systemic delivery while also boosting the immune response. To demonstrate this enhanced effect on both tumor growth and survival, a novel recombinant VSV (rVSV)-mIL12-mGMCSF, co-expressing mouse IL-12 (interleukin-12) and GM-CSF (granulocyte-macrophage colony-stimulating factor), was tested alongside rVSV-dM51-GFP (rVSV-GFP) that was injected intratumorally in a syngeneic in vivo C57BL/6 mouse model infused subcutaneously with B16-F10 melanoma cells. The pilot study tested the effect of two viral injections 4 days apart and demonstrated that treatment with the two rVSVs resulted in partial inhibition of tumor growth (TGII of around 40%) and an increased survival rate in animals from the treatment groups. The effect of the two VSVs on immune cell populations will be investigated in future in vivo studies with an optimized experimental design with multiple higher viral doses, as a lack of this information presents a limitation of this study.

Oncolytic virotherapy in cancer treatment: challenges and optimization prospects

Oncolytic viruses (OVs) are emerging cancer therapeutics that offer a multifaceted therapeutic platform for the benefits of replicating and lysing tumor cells, being engineered to express transgenes, modulating the tumor microenvironment (TME), and having a tolerable safety profile that does not overlap with other cancer therapeutics. The mechanism of OVs combined with other antitumor agents is based on immune-mediated attack resistance and might benefit patients who fail to achieve durable responses after immune checkpoint inhibitor (ICI) treatment. In this Review, we summarize data on the OV mechanism and limitations of monotherapy, which are currently in the process of combination partner development, especially with ICIs. We discuss some of the hurdles that have limited the preclinical and clinical development of OVs. We also describe the available data and provide guidance for optimizing OVs in clinical practice, as well as a summary of approved and promising novel OVs with clinical indications.

Therapeutic cancer vaccines: advancements, challenges, and prospects

With the development and regulatory approval of immune checkpoint inhibitors and adoptive cell therapies, cancer immunotherapy has undergone a profound transformation over the past decades. Recently, therapeutic cancer vaccines have shown promise by eliciting de novo T cell responses targeting tumor antigens, including tumor-associated antigens and tumor-specific antigens. The objective was to amplify and diversify the intrinsic repertoire of tumor-specific T cells. However, the complete realization of these capabilities remains an ongoing pursuit. Therefore, we provide an overview of the current landscape of cancer vaccines in this review. The range of antigen selection, antigen delivery systems development the strategic nuances underlying effective antigen presentation have pioneered cancer vaccine design. Furthermore, this review addresses the current status of clinical trials and discusses their strategies, focusing on tumor-specific immunogenicity and anti-tumor efficacy assessment. However, current clinical attempts toward developing cancer vaccines have not yielded breakthrough clinical outcomes due to significant challenges, including tumor immune microenvironment suppression, optimal candidate identification, immune response evaluation, and vaccine manufacturing acceleration. Therefore, the field is poised to overcome hurdles and improve patient outcomes in the future by acknowledging these clinical complexities and persistently striving to surmount inherent constraints.

Oncolytic Viruses in the Era of Omics, Computational Technologies, and Modeling: Thesis, Antithesis, and Synthesis

Oncolytic viruses (OVs) are the frontier therapy for refractory cancers, especially in integration with immunomodulation strategies. In cancer immunovirotherapy, the many available "omics" and systems biology technologies generate at a fast pace a challenging huge amount of data, where apparently clashing information mirrors the complexity of individual clinical situations and OV used. In this review, we present and discuss how currently big data analysis, on one hand and, on the other, simulation, modeling, and computational technologies, provide invaluable support to interpret and integrate "omic" information and drive novel synthetic biology and personalized OV engineering approaches for effective immunovirotherapy. Altogether, these tools, possibly aided in the future by artificial intelligence as well, will allow for the blending of the information into OV recombinants able to achieve tumor clearance in a patient-tailored way. Various endeavors to the envisioned "synthesis" of turning OVs into personalized theranostic agents are presented.

Utilizing immunogenomic approaches to prioritize targetable neoantigens for personalized cancer immunotherapy

Advancements in sequencing technologies and bioinformatics algorithms have expanded our ability to identify tumor-specific somatic mutation-derived antigens (neoantigens). While recent studies have shown neoantigens to be compelling targets for cancer immunotherapy due to their foreign nature and high immunogenicity, the need for increasingly accurate and cost-effective approaches to rapidly identify neoantigens remains a challenging task, but essential for successful cancer immunotherapy. Currently, gene expression analysis and algorithms for variant calling can be used to generate lists of mutational profiles across patients, but more care is needed to curate these lists and prioritize the candidate neoantigens most capable of inducing an immune response. A growing amount of evidence suggests that only a handful of somatic mutations predicted by mutational profiling approaches act as immunogenic neoantigens. Hence, unbiased screening of all candidate neoantigens predicted by Whole Genome Sequencing/Whole Exome Sequencing may be necessary to more comprehensively access the full spectrum of immunogenic neoepitopes. Once putative cancer neoantigens are identified, one of the largest bottlenecks in translating these neoantigens into actionable targets for cell-based therapies is identifying the cognate T cell receptors (TCRs) capable of recognizing these neoantigens. While many TCR-directed screening and validation assays have utilized bulk samples in the past, there has been a recent surge in the number of single-cell assays that provide a more granular understanding of the factors governing TCR-pMHC interactions. The goal of this review is to provide an overview of existing strategies to identify candidate neoantigens using genomics-based approaches and methods for assessing neoantigen immunogenicity. Additionally, applications, prospects, and limitations of some of the current single-cell technologies will be discussed. Finally, we will briefly summarize some of the recent models that have been used to predict TCR antigen specificity and analyze the TCR receptor repertoire.

Oncolytic viruses improve cancer immunotherapy by reprogramming solid tumor microenvironment

Immunotherapies using immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR) T-cell therapy have achieved successful results against several types of human tumors, particularly hematological malignancies. However, their clinical results for the treatment of solid tumors remain poor and unsatisfactory. The immunosuppressive tumor microenvironment (TME) plays an important role by interfering with intratumoral T-cell infiltration, promoting effector T-cell exhaustion, upregulating inhibitory molecules, inducing hypoxia, and so on. Oncolytic viruses are an encouraging biocarrier that could be used in both natural and genetically engineered platforms to induce oncolysis in a targeted manner. Oncolytic virotherapy (OV) contributes to the reprogramming of the TME, thus synergizing the functional effects of current ICIs and CAR T-cell therapy to overcome resistant barriers in solid tumors. Here, we summarize the TME-related inhibitory factors affecting the therapeutic outcomes of ICIs and CAR T cells and discuss the potential of OV-based approaches to alleviate these barriers and improve future therapies for advanced solid tumors.

Oncolytic virus oHSV2 combined with PD-1/PD-L1 inhibitors exert antitumor activity by mediating CD4 + T and CD8 + T cell infiltration in the lymphoma tumor microenvironment

A novel therapeutic regimen showed that the oncolytic type II herpes simplex virus (oHSV2) was able to prevent colorectal cancer growth, recurrence, and metastasis. However, no study has yet explored whether oHSV2 has an impact on the development of diffuse large B-cell lymphoma (DLBCL). We chose the clinical chemotherapeutic drug doxorubicin (DOX) as a positive control to evaluate the effect of oHSV2 infection on the apoptotic, invasive, and proliferative capacity of DLBCL cells. We next further explored the therapeutic efficacy of oncolytic virus oHSV2 or DOX in DLBCL tumor bearing BALB/c mice, and evaluated the infiltration of CD8 + T cells and CD4 + T cells in tumor tissues. A pathological approach was used to explore the effects of oHSV2 on various organs of tumor bearing mice, including the heart, liver, and kidney. Next, SU-DHL-4 cells were co-cultured with cytotoxic T lymphocytes (CTLs) to mimic the tumor immune microenvironment (TME), to explore the impact of oHSV2 on the immune environment at the cellular level, and then analyzed the relationship between oHSV2 and the PD-1/PD-L1 immune-checkpoint. Subsequently, we further validated the efficacy of combined oHSV2 and PD-L1 treatment on transplanted tumor growth in mice at the in vivo level. DLBCL cells were sensitive to the action of the oncolytic virus oHSV2, and the decline in their proliferative activity showed a time-and dose-dependent manner. oHSV2 and DOX intervention preeminently increased the cell apoptosis, restrained cell proliferation and invasion, with the greatest changes occurring in response to oHSV2 infection. oHSV2 application effectively improved the immune status of the tumor microenvironment, favoring the invasion of CD8 + T and CD4 + T cells, thereby enhancing their antitumor effects. Besides, oHSV2 treatment has a safety profile in the organs of tumor bearing mice and indeed inhibits the PD-1/PD-L1 immune checkpoint in DLBCL. Interestingly, the combination of oHSV2 and PD-L1 antibodies results in more profound killing of DLBCL cells than oHSV2 infection alone, with a significant increase in the proportion of CD4 + T cells and CD8 + T cells. The antitumor effect was the best after combining oHSV2 and PD-L1 antibodies, suggesting that the combination therapy of oHSV2 and PD-L1 would have a better prospect for clinical application.

Oncolytic viral therapy as promising immunotherapy against glioma

Glioma is a common primary central nervous system malignant tumor in clinical, traditional methods such as surgery and chemoradiotherapy are not effective in treatment. Therefore, more effective treatments need to be found. Oncolytic viruses (OVs) are a new type of immunotherapy that selectively infects and kills tumor cells instead of normal cells. OVs can mediate antitumor immune responses through a variety of mechanisms, and have the ability to activate antitumor immune responses, transform the tumor microenvironment from “cold” to “hot,” and enhance the efficacy of immune checkpoint inhibitors. Recently, a large number of preclinical and clinical studies have shown that OVs show great prospects in the treatment of gliomas. In this review, we summarize the current status of glioma therapies with a focus on OVs. First, this article introduces the current status of treatment of glioma and their respective shortcomings. Then, the important progress of OVs of in clinical trials of glioma is summarized. Finally, the urgent challenges of oncolytic virus treatment for glioma are sorted out, and related solutions are proposed. This review will help to further promote the use of OVs in the treatment of glioma.

Intratumoral delivery of a Tim-3 antibody-encoding oncolytic adenovirus engages an effective antitumor immune response in liver cancer

BACKGROUND AND PURPOSE

The use of oncolytic viruses as a gene therapy vector is an area of active biomedical research, particularly in the context of cancer treatment. However, the actual therapeutic success of this approach to tumor elimination remains limited. As such, the present study was developed with the goal of simultaneously enhancing the antitumor efficacy of oncolytic viruses and the local immune response by combining the Ad-GD55 oncolytic adenovirus and an antibody specific for the TIM-3 immune checkpoint molecule (α-TIM-3).

APPROACH AND KEY RESULTS

The results of Virus and cell-mediated cytotoxicity assay, qPCR, and Western immunoblotting showed that Ad-GD55-α-Tim-3 oncolytic adenovirus is capable of inducing α-TIM-3 expression within hepatoma cells upon infection, and Ad-GD55-α-TIM-3 exhibited inhibitory efficacy superior to that of Ad-GD55 when used to treat these tumor cells together with the induction of enhanced intracellular immunity. In vivo experiments revealed that Ad-GD55-α-TIM-3 administration was sufficient to inhibit tumor growth and engage in a more robust local immune response within the simulated tumor immune microenvironment.

CONCLUSION AND IMPLICATIONS

These results highlighted the promising therapeutic effects of Ad-GD55-α-TIM-3 oncolytic adenovirus against HCC in vitro and in vivo. As such, this Ad-GD55-α-TIM-3 oncolytic adenovirus may represent a viable approach to the treatment of hepatocellular carcinoma.

Nanoassembly of doxorubicin-conjugated polyphosphoester and siRNA simultaneously elicited macrophage- and T cell- mediated anticancer immune response for cancer therapy

Efficiently reawakening immune cells, including T cells and macrophages, to eliminate tumor cells is a promising strategy for cancer treatment, but remains a huge challenge nowadays. Herein, a nanoassembly formed by doxorubicin (DOX)-conjugated polyphosphoester (PP-(hDOX)) and CD47-targeting siRNA (siCD47) via electrostatic and π-π stacking interactions, termed as PP-(hDOX&siCD47), was developed to reawaken the T cell and macrophage-mediated anticancer activity. The PP-(hDOX&siCD47) could efficiently blockade antiphagocytic signal by downregulation of CD47 expression to reactive macrophage-mediated anticancer immunotherapy. Moreover, the conjugated DOX of PP-(hDOX&siCD47) can perform the chemotherapy towards tumor cells and also elicit the T cell-mediated anticancer immune response via immunogenic cell death (ICD) effect. Therefore, the PP-(hDOX&siCD47) treatment could significantly increase M1-like macrophages proportion and tumor infiltration of CD8+ T cells, while the proportions of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) were considerably reduced in tumor tissue, eventually achieving significantly tumor growth inhibition. Overall, this study provides a simple siRNA and DOX codelivery approach to simultaneously elicit the macrophage- and T cell-mediated anticancer immune response for cancer therapy.

Inactivation of the DNA-sensing pathway facilitates oncolytic herpes simplex virus inhibition of pancreatic ductal adenocarcinoma growth

Oncolytic viruses are a new class of therapeutic agents for the treatment of cancer that have shown promising results in clinical trials. Oncolytic virus-mediated tumor rejection is highly dependent on viral replication in tumor cells to induce cell death. However, the antiviral immune response of tumor cells limits the replication capacity of oncolytic viruses. We hypothesized that inhibition of the antiviral immune response in infected cells would enhance the antitumor effect. Here, we confirmed that ablation of the key adaptor protein of cellular immunity, STING, significantly suppressed the antiviral immune response and promoted oncolytic herpes simplex virus-1 (oHSV1) proliferation in tumor cells. In a murine pancreatic ductal adenocarcinoma (PDAC) model, oHSV1 enhanced tumor suppression and prolonged the survival of mice in the absence of STING. On this basis, we further found that the TBK1 inhibitor can also significantly enhance the tumor-control ability of oHSV1. Our studies provide a novel strategy for oncolytic virus therapy by inhibiting the intrinsic antiviral response in solid tumors to improve antitumor efficacy.

[Oncolytic viruses: Actors and deliverers of therapeutic proteins against tumors]

The discovery of the unique ability of certain viruses to specifically target cancer cells has led to significant advancements in cancer immunotherapy research. In addition to inducing specific lysis of cancer cells, oncolytic viruses (OV) have been genetically modified to express molecules of interest within the tumor bed. The use of OV as vectors for therapeutic molecules has allowed to enhance antitumor responses while limiting the adverse effects associated with systemic administration of the molecule. Other studies are currently focused on delaying the neutralization and clearance of the virus by the host's immune system and improving its delivery insight tumors.

Optimal delivery of RNA interference by viral vectors for cancer therapy

In recent years, there has been a surge in the innovative modification and application of the viral vector-based gene therapy field. Significant and consistent improvements in the engineering, delivery, and safety of viral vectors have set the stage for their application as RNA interference (RNAi) delivery tools. Viral vector-based delivery of RNAi has made remarkable breakthroughs in the treatment of several debilitating diseases and disorders (e.g., neurological diseases); however, their novelty has yet to be fully applied and utilized for the treatment of cancer. This review highlights the most promising and emerging viral vector delivery tools for RNAi therapeutics while discussing the variables limiting their success and suitability for cancer therapy. Specifically, we outline different integrating and non-integrating viral platforms used for gene delivery, currently employed RNAi targets for anti-cancer effect, and various strategies used to optimize the safety and efficacy of these RNAi therapeutics. Most importantly, we provide great insight into what challenges exist in their application as cancer therapeutics and how these challenges can be effectively navigated to advance the field.