Thymosin α1 reverses oncolytic adenovirus-induced M2 polarization of macrophages to improve antitumor immunity and therapeutic efficacy.

Although oncolytic adenoviruses are widely studied for their direct oncolytic activity and immunomodulatory role in cancer immunotherapy, the immunosuppressive feedback loop induced by oncolytic adenoviruses remains to be studied. Here, we demonstrate that type V adenovirus (ADV) induces the polarization of tumor-associated macrophages (TAMs) to the M2 phenotype and increases the infiltration of regulatory T cells (Tregs) in the tumor microenvironment (TME). By selectively compensating for these deficiencies, thymosin alpha 1 (Tα1) reprograms "M2-like" TAMs toward an antitumoral phenotype, thereby reprogramming the TME into a state more beneficial for antitumor immunity. Moreover, ADVTα1 is constructed by harnessing the merits of all the components for the aforementioned combinatorial therapy. Both exogenously supplied and adenovirus-produced Tα1 orchestrate TAM reprogramming and enhance the antitumor efficacy of ADV via CD8+ T cells, showing promising prospects for clinical translation. Our findings provide inspiration for improving oncolytic adenovirus combination therapy and designing oncolytic engineered adenoviruses.

Smart Accumulating Dual-Targeting Lipid Envelopes Equipping Oncolytic Adenovirus for Enhancing Cancer Gene Therapeutic Efficacy.

Systemic delivery of oncolytic adenovirus (oAd) for cancer gene therapy must overcome several limitations such as rapid clearance from the blood, nonspecific accumulation in the liver, and insufficient delivery to the tumor tissues. In the present report, a tumor microenvironment-triggered artificial lipid envelope composed of a pH-responsive sulfamethazine-based polymer (PUSSM)-conjugated phospholipid (DOPE-HZ-PUSSM) and another lipid decorated with epidermal growth factor receptor (EGFR) targeting peptide (GE11) (GE11-DOPE) was utilized to encapsulate replication-incompetent Ad (dAd) or oAd coexpressing short-hairpin RNA (shRNA) against Wnt5 (shWnt5) and decorin (dAd/LP-GE-PS or oAd/LP-GE-PS, respectively). In vitro studies demonstrated that dAd/LP-GE-PS transduced breast cancer cells in a pH-responsive and EGFR-specific manner, showing a higher level of transduction than naked Ad under a mildly acidic pH of 6.0 in EGFR-positive cell lines. In vivo biodistribution analyses revealed that systemic administration of oAd/LP-GE-PS leads to a significantly higher level of intratumoral virion accumulation compared to naked oAd, oAd encapsulated in a liposome without PUSSM or EGFR targeting peptide moiety (oAd/LP), or oAd encapsulated in a liposome with EGFR targeting peptide alone (oAd/LP-GE) in an EGFR overexpressing MDA-MB-468 breast tumor xenograft model, showing that both pH sensitivity and EGFR targeting ability were integral to effective systemic delivery of oAd. Further, systemic administration of all liposomal oAd formulations (oAd/LP, oAd/LP-GE, and oAd/LP-GE-PS) showed significantly attenuated hepatic accumulation of the virus compared to naked oAd. Collectively, our findings demonstrated that pH-sensitive and EGFR-targeted liposomal systemic delivery of oAd can be a promising strategy to address the conventional limitations of oAd to effectively treat EGFR-positive cancer in a safe manner.

Development of a novel oncolytic adenovirus controlled by CDX2 promoter for esophageal adenocarcinoma therapy.

BACKGROUND: Prognosis of esophageal adenocarcinoma (EAC) is still poor. Therefore, the development of novel therapeutic modalities is necessary to improve therapeutic outcomes in EAC. Here, we report a novel promoter-controlled oncolytic adenovirus targeting CDX2 (Ad5/3-pCDX2) and its specific anticancer effect for EAC. METHODS: We used OE19, OE33, HT29, MKN28, RH30, and HEL299 cell lines. To establish CDX2 overexpressing OE19 cells, pCMV-GLI1 plasmid was transfected to OE19 (OE19 + GLI1). The virus replication and cytocidal effect of replication competent Ad5/3-pCDX2 were analyzed in vitro. Antitumor effect of Ad5/3-pCDX2 was assessed in xenograft mouse models by intratumoral injection of the viruses. Finally, efficacy of combination therapy with Ad5/3-pCDX2 and 5FU was evaluated. RESULTS: EAC cells and HT29 showed high mRNA levels of CDX2, but not MKN28, RH30, and HEL299. We confirmed that deoxycholic acid (DCA) exposure enhanced CDX2 expression in EAC cells and OE19 + GLI1 had persistent CDX2 overexpression without DCA. Ad5/3-pCDX2 showed stronger cytocidal effect in OE19 + GLI1 than OE19, whereas Ad5/3-pCDX2 did not kill CDX2-negative cells. Ad5/3-pCDX2 was significantly replicated in EAC cells and the virus replication was higher in OE19 + GLI1 and OE19 with DCA compared to OE19 without DCA exposure. In vivo, Ad5/3-pCDX2 significantly suppressed OE19 tumor growth and the antitumor effect was enhanced in OE19 + GLI1 tumor. In contrast, Ad5/3-pCDX2 did not show significant antitumor effect in MKN28 tumor. Moreover, Ad5/3-pCDX2 significantly increased the efficacy of 5FU in vitro and in vivo. CONCLUSIONS: Ad5/3-pCDX2 showed specific anticancer effect for EAC, which was enhanced by bile acid exposure. Ad5/3-pCDX2 has promising potential for EAC therapy in the clinical setting.

Oncolytic adenovirus encoding decorin and CD40 ligand inhibits tumor growth and liver metastasis via immune activation in murine colorectal tumor model.

Colorectal cancer (CRC) is the second common cause of cancer mortality worldwide, and it still lacks effective approaches for relapsed and metastatic CRC. Recently, oncolytic virus has been emerged as a promising immune therapeutic strategy. In this study, we develop a novel oncolytic adenovirus, rAd.mDCN.mCD40L, which drive oncolytic activity by telomerase reverse transcriptase promoter (TERTp). rAd.mDCN.mCD40L expressed both mouse genes of decorin (mDCN) and CD40 ligand (mCD40L), and produced effective cytotoxicity in both human and mouse CRC cells. Moreover, oncolytic adenovirus mediated mDCN over-expression inhibited Met expression in vitro. In CT26 subcutaneous tumor model, intratumorally delivery of oncolytic adenoviruses could inhibit tumor growth and liver metastasis, while mDCN and/or mCD40L armed oncolytic adenoviruses produced much more impressive responses. No obvious toxicity was detected in lung, liver and spleen. Moreover, mDCN and/or mCD40L armed oncolytic adenoviruses altered the immune state to activate anti-tumor responses, including increasing CD8+ T effector cells and CD4+ memory T cells, reducing MDSCs and Tregs in peripheral blood. Furthermore, mDCN and/or mCD40L armed oncolytic adenoviruses mediated mDCN and/or mCD40L expression in tumors, and up-regulated Th1 cytokines and reduced Th2 cytokines in tumors, which will be benefit for remodeling tumor microenvironment. Importantly, rAd.mDCN.mCD40L and rAd.mCD40L prevented tumor liver metastasis much more effectively than rAd.Null and rAd.mDCN. Therefore, rAd.mDCN.mCD40L and rAd.mCD40L are promising approaches for CRC therapy.

Advancing Lung Cancer Treatment with Combined c-Met Promoter-Driven Oncolytic Adenovirus and Rapamycin.

Lung cancer remains a formidable health challenge due to its high mortality and morbidity rates. Non-small cell lung cancer (NSCLC) constitutes approximately 85% of all lung cancer cases, with small cell lung cancer (SCLC) accounting for the remainder. Both NSCLC and SCLC cells express receptor tyrosine kinases, which may be overexpressed or mutated in lung cancer, leading to increased activation. The c-Met receptor tyrosine kinase, crucial for cell transformation and tumor growth, invasion, and metastasis, became the focus of our study. We used an E1B55KD-deleted, replication-selective oncolytic adenovirus (Ad.What), driven by the c-Met promoter, targeting lung cancer cells with c-Met overexpression, thus sparing normal cells. Previous studies have shown the enhanced antitumor efficacy of oncolytic adenoviruses when combined with chemotherapeutic agents. We explored combining rapamycin, a selective mTOR inhibitor with promising clinical trial outcomes for various cancers, with Ad.What. This combination increased infectivity by augmenting the expression of coxsackievirus and adenovirus receptors and αV integrin on cancer cells and induced autophagy. Our findings suggest that combining a c-Met promoter-driven oncolytic adenovirus with rapamycin could be an effective lung cancer treatment strategy, offering a targeted approach to exploit lung cancer cells' vulnerabilities, potentially marking a significant advancement in managing this deadly disease.

Treatment of intracranial inflammatory myofibroblastic tumor with PD-L1 inhibitor and novel oncolytic adenovirus Ad-TD-nsIL12: a case report and literature review.

Inflammatory myofibroblastic tumor (IMT) is a rare pathological entity first described in 1939. This lesion is most commonly found in the lungs, but cases involving other systems, such as the central nervous system known as intracranial IMT (IIMT), have also been reported. Diagnosis currently relies on pathological results due to the lack of characteristic imaging changes. Surgical resection is an effective treatment, though the disease is invasive and may recur. Previous literature has reported a high level of programmed death 1 (PD-1) expression in IMT tissues, suggesting that immunotherapy may be effective for this condition. In this case report, we present a middle-aged male who received PD-1 inhibitor and oncolytic adenovirus (Ad-TD-nsIL12) treatment after IIMT resection surgery. This successful approach provides a new direction for the treatment of IIMT.

Enhancing the Antitumor Efficacy of Oncolytic Adenovirus Through Sonodynamic Therapy-Augmented Virus Replication.

The therapeutic efficacy of oncolytic adenoviruses (OAs) relies on efficient viral transduction and replication. However, the limited expression of coxsackie-adenovirus receptors in many tumors, along with the intracellular antiviral signaling, poses significant obstacles to OA infection and oncolysis. Here, we present sonosensitizer-armed OAs (saOAs) that potentiate the antitumor efficacy of oncolytic virotherapy through sonodynamic therapy-augmented virus replication. The saOAs could not only efficiently infect tumor cells via transferrin receptor-mediated endocytosis but also exhibit enhanced viral replication and tumor oncolysis under ultrasound irradiation. We revealed that the sonosensitizer loaded on the viruses induced the generation of ROS within tumor cells, which triggered JNK-mediated autophagy, ultimately leading to the enhanced viral replication. In mouse models of malignant melanoma, the combination of saOAs and sonodynamic therapy elicited a robust antitumor immune response, resulting in significant inhibition of melanoma growth and improved host survival. This work highlights the potential of sonodynamic therapy in enhancing the effectiveness of OAs and provides a promising platform for fully exploiting the antitumor efficacy of oncolytic virotherapy.

Mesenchymal stromal cells protect combined oncolytic and helper-dependent adenoviruses from humoral immunity.

Systemic delivery of oncolytic and immunomodulatory adenoviruses may be required for optimal effects on human malignancies. Mesenchymal stromal cells (MSCs) can serve as delivery systems for cancer therapeutics due to their ability to transport and shield these agents while homing to tumors. We now use MSCs to deliver a clinically validated binary oncolytic and helper-dependent adenovirus combination (CAdVEC) to tumor cells. We show successful oncolysis and helper-dependent virus function in tumor cells even in the presence of plasma from adenovirus-seropositive donors. In both two- and three-dimensional cultures, CAdVEC function is eliminated even at high dilutions of seropositive plasma but is well sustained when CAdVEC is delivered by MSCs. These results provide a robust in vitro model to measure oncolytic and helper-dependent virus spread and demonstrate a beneficial role of using MSCs for systemic delivery of CAdVEC even in the presence of a neutralizing humoral response.

Overcoming effector T cell exhaustion in ovarian cancer ascites with a novel adenovirus encoding for a MUC1 bispecific antibody engager and IL-2 cytokine.

T cell-focused cancer immunotherapy including checkpoint inhibitors and cell therapies has been rapidly evolving over the past decade. Nevertheless, there remains a major unmet medical need in oncology generally and immuno-oncology specifically. We have constructed an oncolytic adenovirus, Ad5/3-E2F-d24-aMUC1aCD3-IL-2 (TILT-322), which is armed with a human aMUC1aCD3 T cell engager and IL-2. TILT-322 treatment stimulated T cell cytotoxicity through the increased presence of granzyme B, perforin, and interferon-gamma. Additional immune profiling indicated TILT-322 increased gamma delta T cell activation and impacted other cell types such as natural killer cells and natural killer-like T cells that are traditionally involved in cancer immunotherapy. TILT-322 treatment also decreased the proportion of exhausted CD8+ T cells as demarked by immune checkpoint expression in ovarian ascites samples. Overall, our data showed that TILT-322 treatment led to an enhanced T cell activation and reversed T cell exhaustion translating into high antitumor efficacy when given locally or intravenously. The analysis of blood and tumors isolated from an in vivo patient-derived ovarian cancer xenograft model suggested TILT-322 mediated tumor control through improved T cell functions. Therefore, TILT-322 is a promising novel anti-tumor agent for clinical translation.

Syngeneic mesenchymal stem cells loaded with telomerase-dependent oncolytic adenoviruses enhance anti-metastatic efficacy.

Oncolytic adenoviruses have emerged as a promising therapeutic approach for cancer therapy. However, systemic delivery of the viruses to metastatic tumors remains a major challenge. Mesenchymal stem cells (MSCs) possess tumor tropism property and can be used as cellular vehicles for delivering oncolytic adenoviruses to tumor sites. Since telomerase activity is found in ~90% of human carcinomas, but undetected in normal adult cells, the human telomerase reverse transcriptase gene (TERT) promoter can be exploited for regulating the replication of oncolytic adenoviruses. Here, we evaluated the antitumor effects of syngeneic murine MSCs loaded with the luciferase-expressing, telomerase-dependent oncolytic adenovirus Ad.GS2 (MSC-Ad.GS2) and Ad.GS2 alone on metastatic MBT-2 bladder tumors. MSCs supported a low degree of Ad.GS2 replication, which could be augmented by coculture with MBT-2 cells or tumor-conditioned medium (TCM), suggesting that viral replication is increased when MSC-Ad.GS2 migrates to tumor sites. MBT-2 cells and TCM enhanced viral replication in Ad.GS2-infected MSCs. SDF-1 is a stem cell homing factor. Our results suggest that the SDF-1/STAT3/TERT signaling axis in MSCs in response to the tumor microenvironment may contribute to the enhanced replication of Ad.GS2 carried by MSCs. Notably, we demonstrate the potent therapeutic efficacy of systemically delivered MSC-Ad.GS2 in pleural disseminated tumor and experimental metastasis models using intrapleural and tail vein injection of MBT-2 cells, respectively. Treatment with MSC-Ad.GS2 significantly reduced tumor growth and prolonged the survival of mice bearing metastatic bladder tumors. Since telomerase is expressed in a broad spectrum of cancers, this therapeutic strategy may be broadly applicable.

Antitumor Effect and Immunomodulatory Mechanism of "Oncolytic Extracellular Vesicles".

Enhancing the antitumor immune response and targeting ability of oncolytic viruses will improve the effect of tumor immunotherapy. Through infecting neural stem cells (NSCs) with a capsid dual-modified oncolytic adenovirus (CRAd), we obtained and characterized the "oncolytic extracellular vesicles" (CRAdEV) with improved targeted infection and tumor killing activity compared with CRAd. Both ex vivo and in vivo studies revealed that CRAdEV activated innate immune cells and importantly enhanced the immunomodulatory effect compared to CRAd. We found that CRAdEV effectively increased the number of DCs and activated CD4+ and CD8+ T cells, significantly increased the number and activation of B cells, and produced higher levels of tumor-specific antibodies, thus eliciting enhanced antitumor activity compared with CRAd in a B16 xenograft immunocompetent mice model. This study provides a novel approach to oncolytic adenovirus modification and demonstrates the potential of "oncolytic extracellular vesicles" in antitumor immunotherapy.

A PD-L1 tropism-expanded oncolytic adenovirus enhanced gene delivery efficiency and anti-tumor effects.

Recombinant adenovirus serotype 5 (Ad5)-mediated virotherapy is a maturing technique in cancer treatment. However, the utility of adenovirus (Ad) has been limited by low expression of coxsackievirus and adenovirus receptor (CAR) in cancer cells resulting in poor infectivity of Ads. To overcome the problem, we aimed to develop a novel tropism-modified oncolytic adenovirus, ZD55-F-HI-sPD-1-EGFP, which contains the epitope of PD-1 (70-77aa) at the HI-loop of Ad fiber. Trimerization of Fiber-sPD-1 was confirmed by immunoblot analysis. ZD55-F-HI-sPD-1-EGFP shows a remarkable improvement in viral infection rate and gene transduction efficiency in the PD-L1-positive cancer cells. Competition assays with a PD-L1 protein reveals that cell internalization of ZD55-F-HI-sPD-1-EGFP is mediated by both CAR and PD-L1 at a high dose. The progeny virus production capacity showed that sPD-1 incorporated fiber-modified oncolytic Ad replication was not affected. Furthermore, treating with ZD55-F-HI-sPD-1-EGFP significantly increased viral infection rate and enhanced anti-tumor effect in vivo. This study demonstrates that the strategy to expand tropism of oncolytic Ad may significantly improve therapeutic profile for cancer treatment.

Priming with oncolytic adenovirus followed by anti-PD-1 and paclitaxel treatment leads to improved anti-cancer efficacy in the 3D TNBC model.

Triple-negative breast cancer (TNBC) is considered one of the most incurable malignancies due to its clinical characteristics, including high invasiveness, high metastatic potential, proneness to relapse, and poor prognosis. Therefore, it remains a critical unmet medical need. On the other hand, poor delivery efficiency continues to reduce the efficacy of anti-cancer therapeutics developed against solid tumours using various strategies, such as genetically engineered oncolytic vectors used as nanocarriers. The study was designed to evaluate the anti-tumour efficacy of a novel combinatorial therapy based on oncolytic adenovirus AdV5/3-D24-ICOSL-CD40L with an anti-PD-1 (pembrolizumab) and paclitaxel (PTX). Here, we first tested the antineoplastic effect in two-dimensional (2D) and three-dimensional (3D) breast cancer models in MDA-MB-231, MDA-MB-468 and MCF-7 cells. Then, to further evaluate the efficacy of combinatorial therapy, including immunological aspects, we established a three-dimensional (3D) co-culture model based on MDA-MB-231 cells with peripheral blood mononuclear cells (PBMCs) to create an integrated system that more closely mimics the complexity of the tumour microenvironment and interacts with the immune system. Treatment with OV as a priming agent, followed by pembrolizumab and then paclitaxel, was the most effective in reducing the tumour volume in TNBC co-cultured spheroids. Further, T-cell phenotyping analyses revealed significantly increased infiltration of CD8+, CD4+ T and Tregs cells. Moreover, the observed anti-tumour effects positively correlated with the level of CD4+ T cell infiltrates, suggesting the development of anti-cancer immunity. Our study demonstrated that combining different immunotherapeutic agents (virus, pembrolizumab) with PTX reduced the tumour volume of the TNBC co-cultured spheroids compared to relevant controls. Importantly, sequential administration of the investigational agents (priming with the vector) further enhanced the anti-cancer efficacy in 3D culture over other groups tested. Taken together, these results support further evaluation of the virus in combination with anti-PD-1 and PTX for the treatment of triple-negative breast cancer patients. Importantly, further studies with in vivo models should be conducted to better understand the translational aspects of tested therapy.

Long-Term Follow-Up of Phase I Trial of Oncolytic Adenovirus-Mediated Cytotoxic and Interleukin-12 Gene Therapy for Treatment of Metastatic Pancreatic Cancer.

The long-term follow-up findings of the phase I trial evaluating the efficacy of oncolytic adenovirus-mediated cytotoxic and interleukin-12 gene therapy in metastatic pancreatic cancer (mPC) seem very promising. The study employed a replication-competent Adenovector in combination with chemotherapy in a dose-escalation format. The trial demonstrated a clinically meaningful median overall survival (OS) benefit, with patients in the highest dose cohort exhibiting an impressive median OS of 18.4 months. This contrasts starkly with patients receiving lower doses who experienced a median OS of 4.8 and 3.5 months, respectively. Remarkably, subject number 10, who received the highest dose, demonstrated an extraordinary survival of 59.1 months, presenting a compelling case for further exploration. Additionally, this patient displayed complete responses in lung and liver metastases, a rare occurrence in mPC treatment. Statistical analyses supported the observed survival benefit. The unprecedented OS results emphasize the potential of this treatment strategy and pave the way for future investigations into this promising gene therapy approach.

p53-Armed Oncolytic Virotherapy Improves Radiosensitivity in Soft-Tissue Sarcoma by Suppressing BCL-xL Expression.

Soft-tissue sarcoma (STS) is a heterogeneous group of rare tumors originating predominantly from the embryonic mesoderm. Despite the development of combined modalities including radiotherapy, STSs are often refractory to antitumor modalities, and novel strategies that improve the prognosis of STS patients are needed. We previously demonstrated the therapeutic potential of two telomerase-specific replication-competent oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702, in human STS cells. Here, we demonstrate in vitro and in vivo antitumor effects of OBP-702 in combination with ionizing radiation against human STS cells (HT1080, NMS-2, SYO-1). OBP-702 synergistically promoted the antitumor effect of ionizing radiation in the STS cells by suppressing the expression of B-cell lymphoma-X large (BCL-xL) and enhancing ionizing radiation-induced apoptosis. The in vivo experiments demonstrated that this combination therapy significantly suppressed STS tumors' growth. Our results suggest that OBP-702 is a promising antitumor reagent for promoting the radiosensitivity of STS tumors.

Conditionally replicative adenovirus as a therapy for malignant peripheral nerve sheath tumors.

Oncolytic adenoviruses (Ads) stand out as a promising strategy for the targeted infection and lysis of tumor cells, with well-established clinical utility across various malignancies. This study delves into the therapeutic potential of oncolytic Ads in the context of neurofibromatosis type 1 (NF1)-associated malignant peripheral nerve sheath tumors (MPNSTs). Specifically, we evaluate conditionally replicative adenoviruses (CRAds) driven by the cyclooxygenase 2 (COX2) promoter, as selective agents against MPNSTs, demonstrating their preferential targeting of MPNST cells compared with non-malignant Schwann cell control. COX2-driven CRAds, particularly those with modified fiber-knobs exhibit superior binding affinity toward MPNST cells and demonstrate efficient and preferential replication and lysis of MPNST cells, with minimal impact on non-malignant control cells. In vivo experiments involving intratumoral CRAd injections in immunocompromised mice with human MPNST xenografts significantly extend survival and reduce tumor growth rate compared with controls. Moreover, in immunocompetent mouse models with MPNST-like allografts, CRAd injections induce a robust infiltration of CD8+ T cells into the tumor microenvironment (TME), indicating the potential to promote a pro-inflammatory response. These findings underscore oncolytic Ads as promising, selective, and minimally toxic agents for MPNST therapy, warranting further exploration.

Harnessing adenovirus in cancer immunotherapy: evoking cellular immunity and targeting delivery in cell-specific manner.

Recombinant adenovirus (rAd) regimens, including replication-competent oncolytic adenovirus (OAV) and replication-deficient adenovirus, have been identified as potential cancer therapeutics. OAV presents advantages such as selective replication, oncolytic efficacy, and tumor microenvironment (TME) remodeling. In this perspective, the principles and advancements in developing OAV toolkits are reviewed. The burgeoning rAd may dictate efficacy of conventional cancer therapies as well as cancer immunotherapies, including cancer vaccines, synergy with adoptive cell therapy (ACT), and TME reshaping. Concurrently, we explored the potential of rAd hitchhiking to adoptive immune cells or stem cells, highlighting how this approach facilitates synergistic interactions between rAd and cellular therapeutics at tumor sites. Results from preclinical and clinical trials in which immune and stem cells were infected with rAd have been used to address significant oncological challenges, such as postsurgical residual tumor tissue and metastatic tissue. Briefly, rAd can eradicate tumors through various mechanisms, resulting from tumor immunogenicity, reprogramming of the TME, enhancement of cellular immunity, and effective tumor targeting. In this context, we argue that rAd holds immense potential for enhancing cellular immunity and synergistically improving antitumor effects in combination with novel cancer immunotherapies.

Chimeric oncolytic adenovirus evades neutralizing antibodies from human patients and exhibits enhanced anti-glioma efficacy in immunized mice.

Oncolytic viruses are a promising treatment for patients with high-grade gliomas, but neutralizing antibodies can limit their efficacy in patients with prior virus exposure or upon repeated virus injections. Data from a previous clinical trial using the oncolytic adenovirus Delta-24-RGD showed that generation of anti-viral neutralizing antibodies may affect the long-term survival of glioma patients. Past studies have examined the effects of neutralizing antibodies during systemic virus injections, but largely overlooked their impact during local virus injections into the brain. We found that immunoglobulins colocalized with viral proteins upon local oncolytic virotherapy of brain tumors, warranting a strategy to prevent virus neutralization and maximize oncolysis. Thus, we generated a chimeric virus, Delta-24-RGD-H43m, by replacing the capsid protein HVRs from the serotype 5-based Delta-24-RGD with those from the rare serotype 43. Delta-24-RGD-H43m evaded neutralizing anti-Ad5 antibodies and conferred a higher rate of long-term survival than Delta-24-RGD in glioma-bearing mice. Importantly, Delta-24-RGD-H43m activity was significantly more resistant to neutralizing antibodies present in sera of glioma patients treated with Delta-24-RGD during a phase 1 clinical trial. These findings provide a framework for a novel treatment of glioma patients that have developed immunity against Delta-24-RGD.

The combination treatment of oncolytic adenovirus H101 with nivolumab for refractory advanced hepatocellular carcinoma: an open-label, single-arm, pilot study.

BACKGROUND: H101, an innovative oncolytic adenovirus, has shown potential in modifying the tumor microenvironment from immunologically 'cold' to 'hot'. When combined with nivolumab, a programmed cell death protein 1 inhibitor, this synergy may offer substantial therapeutic benefits beyond the capabilities of each agent alone. PATIENTS AND METHODS: In this pilot study, we assessed the efficacy and safety of combining H101 with nivolumab in advanced hepatocellular carcinoma (HCC) patients who failed prior systemic therapy. The participants received initial oncolytic virus (OV) pretreatment with intratumoral H101 injections (5.0 × 1011 vp/0.5 ml/vial, two vials per lesion) on days 1 and 3. Combination therapy started on day 8, with H101 administered every 2 or 4 weeks and nivolumab (240 mg) injections every 2 weeks. Treatment continued up to 12 months or until disease progression, intolerable toxicity, consent withdrawal, or study conclusion. The primary endpoint was the objective response rate (ORR). RESULTS: Between March 2020 and March 2022, 18 of 21 screened patients were assessable, showing an ORR of 11.1% [two cases of partial response (PR) and five cases of stable disease], with extrahepatic injections often leading to favorable outcomes. The disease control rate stood at 38.9%, with a 6-month survival rate of 88.9%. Median progression-free survival was 2.69 months, and overall survival (OS) was 15.04 months. Common adverse events included low-grade fever (100%) and pain related to centesis (33.3%), and no grade 3/4 events were reported. Significantly, local H101 injection showed potential in reversing immune checkpoint inhibitor resistance, evidenced by over 2.5 years of extended OS in PR cases with low α-fetoprotein. Additionally, decreasing neutrophil-to-lymphocyte ratio during OV pretreatment may predict positive outcomes. CONCLUSIONS: This study demonstrates the potential efficacy of combining H101 with nivolumab in treating refractory advanced HCC, with well-tolerated toxicities.

Nanotechnology and nano-sized tools: Newer approaches to circumvent oncolytic adenovirus limitations.

Oncolytic adenoviruses (OAds), engineered Ads preferentially infect and lyse tumor cells, have attracted remarkable attention as immunotherapy weapons for the treatment of various malignancies. Despite hopeful successes in preclinical investigations and translation into clinical phases, they face some challenges that thwart their therapeutic effectiveness, including low infectivity of cancer cells, liver sequestration, pre-existing neutralizing antibodies, physical barriers to the spread of Ads, and immunosuppressive TME. Nanotechnology and nano-sized tools provide several advantages to overcome these limitations of OAds. Nano-sized tools could improve the therapeutic efficacy of OAds by enhancing infectivity and cellular uptake, targeting and protecting from pre-existing immune responses, masking and preventing liver tropism, and co-delivery with other therapeutic agents. Herein, we reviewed the constructs of various OAds and their application in clinical trials, as well as the limitations they have faced. Furthermore, we emphasized the potential applications of nanotechnology to solve the constraints of OAds to improve their anti-tumor activities.