Safety and dose escalation of the targeted oncolytic adenovirus OBP-301 for refractory advanced liver cancer: Phase I clinical trial

Phase 1, open-label, multicenter, dose escalation safety and tolerability study of oncolytic virus OVV-01 in advanced solid tumors

BACKGROUND

OVV-01 is a genetically engineered vesicular stomatitis virus oncolytic virus designed to selectively amplify in tumor cells and express tumor-associated antigen NY-ESO-1. This study was designed to evaluate the safety, tolerability, and efficacy of OVV-01 in patients with advanced solid tumors.

METHODS

This is a phase 1, first-in-human, open-label, multicenter study of OVV-01 in patients with advanced solid tumors. OVV-01 was intratumorally injected biweekly (every two weeks, Q2W), 3 weeks after the first dose for a total of six doses. Dose escalation follows a 3+3 design at four doses of 6×107 Plaue-Forming Unit (PFU), 6×108 PFU, 6×109 PFU, and 1.2×1011 PFU. The primary endpoints were safety and tolerability. The second endpoints included overall response rate (ORR) and disease control rate (DCR) of OVV-01, by investigators per Response Evaluation Criteria in Solid Tumors V.1.1.

RESULTS

18 patients were enrolled into four dose groups, among whom 6 were soft tissue sarcoma (STS). No dose-limiting toxicities and treatment-related severe adverse events were observed. 11 patients were evaluated for efficacy, and the ORR was 27.3%, and the DCR was 63.6%. Among the four evaluable patients with advanced STS, the ORR was 75%. Two patients with STS achieved CR at doses above 6.0×109 PFU.

CONCLUSIONS

The intratumor injection of OVV-01 was safe and well-tolerated in patients with advanced solid tumors. A significant response was observed in patients with STS.

TRIAL REGISTRATION NUMBER

NCT04787003.

Liposomal oncolytic adenovirus as a neoadjuvant therapy for triple-negative breast cancer

Breast cancer remains one of the leading causes of cancer-related death, with triple-negative breast cancer (TNBC) accounting for 15-20% of cases. TNBC, characterized by the absence of ER, PR, and HER2 protein, is an aggressive form of breast cancer that is unresponsive to hormonal therapies and HER2-targeted treatments, with fewer treatment options and poorer prognosis. Oncolytic adenoviruses (Ad) are a potential treatment option for TNBC but require coxsackievirus and adenovirus receptors (CAR) to effectively enter and transduce cancer cells. This study investigates a novel neoadjuvant therapy to improve the efficacy of an oncolytic Ad with human telomerase reverse transcriptase (Ad-hTERT) in CAR-low TNBC tumors using folate surface-modified liposomes to enhance delivery. This therapy helps deescalate treatment by reducing or eliminating the need for checkpoint inhibitors or toxic chemotherapy combinations. In vitro studies using CAR-low TNBC murine 4T1-eGFP cells, CAR-high TNBC human MDA-MB-231-GFP cells and several other TNBC human cancer cell lines with varying CAR expression demonstrated significantly higher cytotoxicity with encapsulated Ad-hTERT compared to Ad-hTERT. Similar results were observed in patient-derived primary TNBC cells. In vivo studies in immunocompetent mice with CAR-low 4T1-eGFP tumors revealed that encapsulated Ad-hTERT, administered as neoadjuvant therapy, resulted in stable or reduced tumor sizes, improved survival rates, higher apoptosis of cancer cells, lower cancer cell proliferation, and increased T-cell infiltration in resected tumors. Furthermore, encapsulated Ad-hTERT prevented lung metastasis and tumor recurrence at the primary site, resulting in higher survival rates in mice. Thus, liposomal encapsulation of Ad may be a viable strategy for treating TNBC.

The Landmark Series: Therapeutic Cancer Vaccine Strategies for Cold Tumors

Immunologically cold tumors present a significant challenge in cancer treatment due to their limited baseline immune infiltration and resistance to immunotherapy. Cancer vaccines offer a promising strategy to overcome this barrier by introducing high-quality, tumor-relevant antigens that can stimulate an effective anti-tumor immune response. Therapeutic cancer vaccines are being explored in the neoadjuvant, adjuvant, and minimal residual disease contexts to enhance immune activation and promote immune cell infiltration and function, with the goal to eradicate malignant cells and improve patient survival. Critical hurdles remain in optimizing antigen selection, determining the most effective vaccine formulations, and defining the ideal clinical setting for vaccine use. Moreover, rational combinations of cancer vaccines with other immune modulators (e.g., adjuvants, immune checkpoint inhibitors, and cytokines) may hold the key to enhancing vaccine efficacy and expanding therapeutic options for difficult-to-treat malignancies. This review examines current advancements in cancer vaccines and their utilization for immunologically cold tumors in the perioperative setting, highlighting ongoing challenges and future directions in this evolving field.

Beyond Telomeres: Unveiling the Extratelomeric Functions of TERT in B-Cell Malignancies

The reactivation of telomerase enables cancer cells to maintain the telomere length, bypassing replicative senescence and achieving cellular immortality. In addition to its canonical role in telomere maintenance, accumulating evidence highlights telomere-length-independent functions of TERT, the catalytic subunit of telomerase. These extratelomeric functions involve the regulation of signaling pathways and transcriptional networks, creating feed-forward loops that promote cancer cell proliferation, resistance to apoptosis, and disease progression. This review explores the complex mechanisms by which TERT modulates key signaling pathways, such as NF-κB, AKT, and MYC, highlighting its role in driving autonomous cancer cell growth and resistance to therapy in B-cell malignancies. Furthermore, we discuss the therapeutic potential of targeting TERT's extratelomeric functions. Unlike telomere-directed approaches, which may require prolonged treatment to achieve effective telomere erosion, inhibiting TERT's extratelomeric functions offers the prospect of rapid tumor-specific effects. This strategy could complement existing chemotherapeutic regimens, providing an innovative and effective approach to managing B-cell malignancies.

Telomeres and telomerase in mesothelioma: Pathophysiology, biomarkers and emerging therapeutic strategies (Review)

Malignant mesothelioma (MM) is a rare but aggressive cancer linked to asbestos exposure and characterized by advanced‑stage disease at presentation. Despite advances in treatment, prognosis remains abysmal, highlighting the imperative for the development of novel biomarkers and treatment approaches. Telomere biology plays a pivotal role in the tumorigenic process and has emerged as a key area in oncology research. Short telomeres have been associated with genomic instability, and substantially shorter telomere length (TL) has been identified in MM, showcasing the potential of TL in risk assessment, early detection, and disease progression monitoring. MM predominantly maintains TL through telomerase activity (TA), which in research has been identified in >90% of MM cases, underscoring the potential of TA as a biomarker in MM. Telomerase reverse transcriptase (TERT) polymorphisms may serve as valuable biomarkers, with research identifying associations between single nucleotide polymorphisms (SNPs) and the risk and prognosis of MM. Additionally, TERT promoter mutations have been associated with poor prognosis and advanced‑stage disease, with the non‑canonical functions of TERT hypothesized to contribute to the development of MM. TERT promoter mutations occur in ~12% of MM cases; C228T, C250T and A161C are the most common, while the distribution and frequency differ depending on histological subtype. Research reveals the promise of the various approaches therapeutically targeting telomerase, with favorable results in pre‑clinical models and inconclusive findings in clinical trials. The present review examines the role of telomere biology in MM and its implications in diagnosis, prognosis, and therapy.

Tumor microbiome: roles in tumor initiation, progression, and therapy

Over the past few years, the tumor microbiome is increasingly recognized for its multifaceted involvement in cancer initiation, progression, and metastasis. With the application of 16S ribosomal ribonucleic acid (16S rRNA) sequencing, the intratumoral microbiome, also referred to as tumor-intrinsic or tumor-resident microbiome, has also been found to play a significant role in the tumor microenvironment (TME). Understanding their complex functions is critical for identifying new therapeutic avenues and improving treatment outcomes. This review first summarizes the origins and composition of these microbial communities, emphasizing their adapted diversity across a diverse range of tumor types and stages. Moreover, we outline the general mechanisms by which specific microbes induce tumor initiation, including the activation of carcinogenic pathways, deoxyribonucleic acid (DNA) damage, epigenetic modifications, and chronic inflammation. We further propose the tumor microbiome may evade immunity and promote angiogenesis to support tumor progression, while uncovering specific microbial influences on each step of the metastatic cascade, such as invasion, circulation, and seeding in secondary sites. Additionally, tumor microbiome is closely associated with drug resistance and influences therapeutic efficacy by modulating immune responses, drug metabolism, and apoptotic pathways. Furthermore, we explore innovative microbe-based therapeutic strategies, such as engineered bacteria, oncolytic virotherapy, and other modalities aimed at enhancing immunotherapeutic efficacy, paving the way for microbiome-centered cancer treatment frameworks.

Hepatocellular carcinoma: signaling pathways and therapeutic advances

Liver cancer represents a major global health concern, with projections indicating that the number of new cases could surpass 1 million annually by 2025. Hepatocellular carcinoma (HCC) constitutes around 90% of liver cancer cases and is primarily linked to factors incluidng aflatoxin, hepatitis B (HBV) and C (HCV), and metabolic disorders. There are no obvious symptoms in the early stage of HCC, which often leads to delays in diagnosis. Therefore, HCC patients usually present with tumors in advanced and incurable stages. Several signaling pathways are dis-regulated in HCC and cause uncontrolled cell propagation, metastasis, and recurrence of HCC. Beyond the frequently altered and therapeutically targeted receptor tyrosine kinase (RTK) pathways in HCC, pathways involved in cell differentiation, telomere regulation, epigenetic modification and stress response also provide therapeutic potential. Investigating the key signaling pathways and their inhibitors is pivotal for achieving therapeutic advancements in the management of HCC. At present, the primary therapeutic approaches for advanced HCC are tyrosine kinase inhibitors (TKI), immune checkpoint inhibitors (ICI), and combination regimens. New trials are investigating combination therapies involving ICIs and TKIs or anti-VEGF (endothelial growth factor) therapies, as well as combinations of two immunotherapy regimens. The outcomes of these trials are expected to revolutionize HCC management across all stages. Here, we provide here a comprehensive review of cellular signaling pathways, their therapeutic potential, evidence derived from late-stage clinical trials in HCC and discuss the concepts underlying earlier clinical trials, biomarker identification, and the development of more effective therapeutics for HCC.

Telomeres, telomerase, and cancer: mechanisms, biomarkers, and therapeutics

Telomeres and telomerase play crucial roles in the initiation and progression of cancer. As biomarkers, they aid in distinguishing benign from malignant tissues. Despite the promising therapeutic potential of targeting telomeres and telomerase for therapy, translating this concept from the laboratory to the clinic remains challenging. Many candidate drugs remain in the experimental stage, with only a few advancing to clinical trials. This review explores the relationship between telomeres, telomerase, and cancer, synthesizing their roles as biomarkers and reviewing the outcomes of completed trials. We propose that changes in telomere length and telomerase activity can be used to stratify cancer stages. Furthermore, we suggest that differential expression of telomere and telomerase components at the subcellular level holds promise as a biomarker. From a therapeutic standpoint, combining telomerase-targeted therapies with drugs that mitigate the adverse effects of telomerase inhibition may offer a viable strategy.

Transferrin-binding domain inserted-adenovirus hexon engineering enables systemic immune evasion and intratumoral T-cell activation

Rationale: Adenovirus-based therapies have encountered significant challenges due to host immunity, particularly from pre-existing antibodies. Many trials have struggled to evade antibody response; however, the efficiency of these efforts was limited by the diversity of antibody Fv-region recognizing multiple amino acid sequences. Methods: In this study, we developed an antibody-evading adenovirus vector by encoding a plasma-rich protein transferrin-binding domain. The coding sequence was employed from Neisseria Meningitides and inserted in the experimentally-optimized site within the adenovirus capsid protein. Result: This engineered antibody-evading oncolytic adenovirus overcame the reduction in productivity and infectivity typically caused by the insertion of a foreign domain. We observed decreased immune recognition and compromised formation of anti-adenovirus antibodies. Furthermore, the anti-tumor efficacy was demonstrated both in vitro and in vivo, with increased recruitment of CD8+ T cells. Conclusion: This novel antibody-evading strategy effectively evades neutralizing antibodies and innate immunity while boosting cytotoxic immunity by recruiting CD8+ T cells at the tumor site. Additionally, this strategy holds potential for application in other gene therapies and adenovirus vectors.

The Potential of Oncolytic Virotherapy in the Treatment of Head and Neck Cancer: A Comprehensive Review

Head and neck cancer (HNC) represents a challenging oncological entity with significant morbidity and mortality rates. Despite advances in conventional therapies, including surgery, chemotherapy, and radiation therapy, the overall survival rates for advanced HNC remain suboptimal. In recent years, the emerging field of oncolytic virotherapy has gained attention as a promising therapeutic approach for various malignancies, including HNC. This review provides a comprehensive overview of the current understanding of oncolytic viruses (Ovs) in the context of HNC treatment, including their mechanisms of action, preclinical and clinical studies, challenges, and future directions. Future oncolytic virotherapy focuses on improving delivery and specificity through nanoparticle carriers and genetic modifications to enhance tumor targeting and immune response. Combining different OVs and integrating them with immunotherapies, such as checkpoint inhibitors, could overcome tumor resistance and improve outcomes. Personalized approaches and rigorous clinical trials are key to ensuring the safety and effectiveness of virotherapy in treating HNC.

Global research trends in the tumor microenvironment of hepatocellular carcinoma: insights based on bibliometric analysis

Objective

This study aimed to use visual mapping and bibliometric analysis to summarize valuable information on the tumor microenvironment (TME)-related research on hepatocellular carcinoma (HCC) in the past 20 years and to identify the research hotspots and trends in this field.

Methods

We screened all of the relevant literature on the TME of HCC in the Web of Science database from 2003 to 2023 and analysed the research hotspots and trends in this field via VOSviewer and CiteSpace.

Results

A total of 2,157 English studies were collected. According to the prediction, the number of papers that were published in the past three years will be approximately 1,394, accounting for 64.63%. China published the most papers (n=1,525) and had the highest total number of citations (n=32,253). Frontiers In Immunology published the most articles on the TME of HCC (n=75), whereas, Hepatology was the journal with the highest total number of citations (n=4,104) and average number of citations (n=91). The four clusters containing keywords such as "cancer-associated fibroblasts", "hepatic stellate cells", "immune cells", "immunotherapy", "combination therapy", "landscape", "immune infiltration", and "heterogeneity" are currently hot research topics in this field. The keywords "cell death", "ferroptosis", "biomarkers", and "prognostic features" have emerged relatively recently, and these research directions are becoming increasingly popular.

Conclusions

We identified four key areas of focus in the study of the TME in HCC: the main components and roles in the TME, immunotherapy, combination therapy, and the microenvironmental landscape. Moreover, the result of our study indicate that effect of ferroptosis on the TME in HCC may become a future research trend.

Progression of oncolytic virus in liver cancer treatment

The liver plays a crucrial role in detoxification, metabolism, and nutrient storage. Because liver cancer ranks among the top three leading causes of death globally, there is an urgent need for developing treatment strategies for liver cancer. Although traditional approaches such as radiation, chemotherapy, surgical removal, and transplantation are widely practiced, the number of patients with liver cancer continues to increase rapidly each year. Some novel therapeutics for liver cancer have been studied for many years. In the past decade, oncolytic therapy has emerged, in which viruses selectively infect and destroy cancer cells while sparing normal cells. However, oncolytic virotherapy for liver cancer remains relatively obscure due to the aggressive nature of the disease and the limited effectiveness of treatment. To keep pace with the latest developments in oncolytic tumor therapy for liver cancer, this review summarizes basic science studies and clinical trials conducted within 5 years, focusing on the efficacy and safety profiles of the five most commonly used oncolytic viruses: herpes simplex virus, adenovirus, influenza virus, vaccinia virus, and coxsackievirus.

The long-term effectiveness and mechanism of oncolytic virotherapy combined with anti-PD-L1 antibody in colorectal cancer patient

Colorectal cancer (CRC) is known to be resistant to immunotherapy. In our phase-I clinical trial, one patient achieved a 313-day prolonged response during the combined treatment of oncolytic virotherapy and immunotherapy. To gain a deeper understanding of the potential molecular mechanisms, we performed a comprehensive multi-omics analysis on this patient and three non-responders. Our investigation unveiled that, initially, the tumor microenvironment (TME) of this responder presented minimal infiltration of T cells and natural killer cells, along with a relatively higher presence of macrophages compared to non-responders. Remarkably, during treatment, there was a progressive increase in CD4+ T cells, CD8+ T cells, and B cells in the responder's tumor tissue. This was accompanied by a significant upregulation of transcription factors associated with T-cell activation and cytotoxicity, including GATA3, EOMES, and RUNX3. Furthermore, dynamic monitoring of peripheral blood samples from the responder revealed a rapid decrease in circulating tumor DNA (ctDNA), suggesting its potential as an early blood biomarker of treatment efficacy. Collectively, our findings demonstrate the effectiveness of combined oncolytic virotherapy and immunotherapy in certain CRC patients and provide molecular evidence that virotherapy can potentially transform a "cold" TME into a "hot" one, thereby improving sensitivity to immunotherapy.

Exploring treatment options in cancer: Tumor treatment strategies

Traditional therapeutic approaches such as chemotherapy and radiation therapy have burdened cancer patients with onerous physical and psychological challenges. Encouragingly, the landscape of tumor treatment has undergone a comprehensive and remarkable transformation. Emerging as fervently pursued modalities are small molecule targeted agents, antibody-drug conjugates (ADCs), cell-based therapies, and gene therapy. These cutting-edge treatment modalities not only afford personalized and precise tumor targeting, but also provide patients with enhanced therapeutic comfort and the potential to impede disease progression. Nonetheless, it is acknowledged that these therapeutic strategies still harbour untapped potential for further advancement. Gaining a comprehensive understanding of the merits and limitations of these treatment modalities holds the promise of offering novel perspectives for clinical practice and foundational research endeavours. In this review, we discussed the different treatment modalities, including small molecule targeted drugs, peptide drugs, antibody drugs, cell therapy, and gene therapy. It will provide a detailed explanation of each method, addressing their status of development, clinical challenges, and potential solutions. The aim is to assist clinicians and researchers in gaining a deeper understanding of these diverse treatment options, enabling them to carry out effective treatment and advance their research more efficiently.

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.

Recent advances of engineered oncolytic viruses-based combination therapy for liver cancer

Liver cancer is a major malignant tumor, which seriously threatens human health and increases the economic burden on patients. At present, gene therapy has been comprehensively studied as an excellent therapeutic measure in liver cancer treatment. Oncolytic virus (OV) is a kind of virus that can specifically infect and kill tumor cells. After being modified by genetic engineering, the specificity of OV infection to tumor cells is increased, and its influence on normal cells is reduced. To date, OV has shown its effectiveness and safety in experimental and clinical studies on a variety of tumors. Thus, this review primarily introduces the current status of different genetically engineered OVs used in gene therapy for liver cancer, focuses on the application of OVs and different target genes for current liver cancer therapy, and identifies the problems encountered in OVs-based combination therapy and the corresponding solutions, which will provide new insights into the treatment of liver cancer.

Regulation of telomerase towards tumor therapy

Cancer is an aging-related disease, while aging plays an important role in the development process of tumor, thus the two are inextricably associated. Telomere attrition is one of the recognized hallmark events of senescence. Hence, targeting telomerase which could extends telomere sequences to treat tumors is widely favored. Cancer cells rely on high activity of telomerase to maintain a strong proliferative potential. By inhibiting the expression or protein function of telomerase, the growth of cancer cells can be significantly suppressed. In addition, the human immune system itself has a defense system against malignant tumors. However, excessive cell division results in dramatic shortening on telomeres and decline in the function of immune organs that facilitates cancer cell evasion. It has been shown that increasing telomerase activity or telomere length of these immune cells can attenuate senescence, improve cellular viability, and enhance the immunosuppressive microenvironment of tumor. In this paper, we review the telomerase-targeting progress using different anti-tumor strategies from the perspectives of cancer cells and immune cells, respectively, as well as tracking the preclinical and clinical studies of some representative drugs for the prevention or treatment of tumors.

Oncolytic Virus Engineering and Utilizations: Cancer Immunotherapy Perspective

Oncolytic viruses have positively impacted cancer immunotherapy over the past 20 years. Both natural and genetically modified viruses have shown promising results in treating various cancers. Various regulatory authorities worldwide have approved four commercial oncolytic viruses, and more are being developed to overcome this limitation and obtain better anti-tumor responses in clinical trials at various stages. Faster advancements in translating research into the commercialization of cancer immunotherapy and a comprehensive understanding of the modification strategies will widen the current knowledge of future technologies related to the development of oncolytic viruses. In this review, we discuss the strategies of virus engineering and the progress of clinical trials to achieve virotherapeutics.