Recently, Genuine Biotech, in collaboration with the First Affiliated Hospital of Zhengzhou University and the Institute of Medicinal Biotechnology at the Chinese Academy of Medical Sciences, published a research paper titled "Azvudine remodels the local immunosuppressive microenvironment and exhibits sustained anti-tumor effects in combination with anti-PD-1 therapies" in Frontiers of Medicine, systematically exploring the anti-tumor efficacy and mechanisms of Azvudine (FNC) combined with anti-PD-1 therapy.
The study confirmed that Azvudine monotherapy significantly inhibits solid tumor growth and remodels the tumor immune microenvironment. When combined with anti-PD-1 antibodies, it produces a synergistic effect, inducing complete and durable tumor regression and establishing long-term immune memory.
This research provides a novel and effective combination treatment strategy to overcome the bottlenecks of existing tumor immunotherapies. If this combination regimen is successfully launched in the future, it has the potential to transform the treatment landscape for solid tumors such as colorectal cancer, offering hope for long-term survival and even clinical cure, particularly for patients unresponsive to current immunotherapies. The corresponding clinical demand and market space may also undergo structural reshaping.
Multi-Level Design Validates Anti-Tumor Mechanism
Previous studies have shown that Azvudine, as a highly selective nucleoside drug with a unique dual mechanism, demonstrates significant potential in inhibiting tumor growth. On one hand, it directly inhibits DNA synthesis in tumor cells, effectively suppressing cancer cell proliferation by terminating DNA chain elongation and interfering with the function of enzymes involved in nucleic acid synthesis in cancer cells. On the other hand, as an immunomodulator that remodels the tumor microenvironment, Azvudine significantly reduces the excessive accumulation of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment while promoting the infiltration and proliferation of CD8⁺ T cells and CD4⁺ T cells, thereby activating the body's own anti-tumor immune response and enhancing overall anti-tumor efficacy.
Based on this foundation, the present study conducted an in-depth exploration centered on the core question of how Azvudine systematically regulates the immunosuppressive microenvironment in solid tumors.
Overall study design and in vitro/in vivo evaluation of FNC's anti-tumor effects
To systematically evaluate the anti-tumor potential of Azvudine, the research team employed a rigorous multi-level validation system. The study first established multiple mouse models, including CT26 colorectal cancer and H22 liver cancer, and conducted comparative analyses under both immunocompetent and immunodeficient backgrounds. Multi-omics technologies, including single-cell RNA sequencing, flow cytometry, and cytokine analysis, were used to dissect its mechanism of action layer by layer, from overall animal phenotypes and tumor microenvironment cell composition to molecular signaling pathways.
In vitro experimental data showed that Azvudine inhibited the proliferation of various tumor cell lines in a time- and dose-dependent manner. Particularly noteworthy were the in vivo results: in immunocompetent tumor-bearing mice, 1 mg/kg FNC produced highly effective and sustained inhibition of tumor growth. The researchers conducted parallel validation in immunodeficient models and found that the anti-tumor effect of the drug was significantly attenuated in immunodeficient mice. This key comparative result confirmed that Azvudine's anti-tumor efficacy is primarily achieved through activation of the host immune system, revealing a unique mechanism of action distinct from traditional chemotherapeutic drugs.
Further analysis of single-cell transcriptomic data from 51,924 cells revealed changes in the tumor microenvironment: FNC treatment significantly increased the proportions of memory T cells, NK cells, and CD8⁺ CTLs in the local tumor microenvironment of tumor-bearing mice, while significantly reducing the proportions of immunosuppressive M2 macrophages and M-MDSCs. This finding explains at the cellular level how Azvudine improves the tumor immune microenvironment.
Activating Immune Response to Achieve Synergistic Enhancement
Previous studies have pointed out that although anti-PD-1 therapy has shown clinical efficacy in some solid tumors, its effectiveness against treated, drug-resistant, or recurrent tumors remains limited. This insufficient efficacy may be primarily attributable to multiple immunosuppressive mechanisms, among which the infiltration of myeloid-derived suppressor cells (MDSCs) may be a key factor, as these cells can inhibit T cell activity and create a local immunosuppressive microenvironment. Therefore, breaking through these barriers and remodeling the immunosuppressive microenvironment is a core challenge in enhancing the efficacy of immunotherapy.
Against this background, having confirmed that Azvudine effectively reduces MDSC infiltration and remodels the tumor immune microenvironment, the researchers further explored the combination effect of Azvudine with anti-PD-1 therapy. Azvudine not only modulates immune cell composition but also induces immunogenic cell death (ICD) in tumor cells—a key mechanism akin to placing "danger signals" on tumor cells—which significantly enhances the immune system's recognition of and response to cancer cells. This mechanism perfectly complements and synergizes with the action of PD-1 inhibitors in relieving immunosuppression.
Azvudine combined with anti-PD-1 therapy achieves complete remission and establishes long-term immune memory in CT26 colon cancer mouse model
In the CT26 colon cancer mouse model, the combination therapy demonstrated significantly superior efficacy compared to monotherapy: all mice in the combination treatment group achieved complete tumor regression within 39 days, with no recurrence observed by the end of the 88-day follow-up period. Of particular note, in subsequent "re-challenge" experiments, mice cured by the combination therapy did not develop tumor growth after re-inoculation with the same tumor cells, confirming that this regimen induces robust immune memory and providing direct evidence for overcoming tumor recurrence and acquired resistance.
In-depth mechanistic studies revealed the molecular basis for this anti-tumor synergistic effect. Through transcriptomic analysis, the researchers found that "PD-1 signaling was the most significantly enriched term," indicating that Azvudine may enhance the efficacy of PD-1 inhibitors by modulating immune checkpoint-related signaling pathways. This multi-target mechanism of action provides a scientific explanation for the synergistic enhancement observed with Azvudine in combination with immunotherapy.
Even more encouraging, this synergistic effect has also been positively validated in other human studies. In an investigator-initiated trial involving human subjects, 100% of non-small cell lung cancer patients who had progressed after last-line treatment achieved effective disease control, while 75% of colorectal cancer patients achieved effective disease control. These positive human clinical data, corroborating the complete tumor regression and immune memory formation observed in this study, collectively point to the significant potential of this combination treatment strategy in addressing unmet clinical needs.
Addressing Clinical Challenges and Unmet Needs
Although tumor immunotherapy has entered a period of rapid development, it still faces significant challenges. Taking colorectal cancer as an example, its incidence ranks third globally and second in China among all malignant tumors. In 2023, there were approximately 2.03 million new cases worldwide. However, according to the National Comprehensive Cancer Network (NCCN) guidelines, immune checkpoint inhibitors are only recommended for metastatic colorectal cancer patients with microsatellite instability-high or mismatch repair deficiency, which accounts for only about 5% of cases.
This means that over 1.9 million new patients worldwide with microsatellite-stable (MSS) disease each year are largely unresponsive to current anti-PD-1/PD-L1 monotherapy, facing the dilemma that traditional regimens based on chemotherapy and targeted therapy have reached their limits and are associated with significant toxicity. Moreover, among patients who initially respond to PD-1 inhibitors, resistance gradually develops over time with prolonged treatment.
The emergence of Azvudine in combination with anti-PD-1 therapy directly targets this industry pain point with an innovative approach. It is not a simple drug combination but achieves a "1+1>2" synergistic effect through complementary mechanisms: Azvudine, as an immunomodulator, effectively reduces the infiltration of immunosuppressive cells such as MDSCs in the tumor microenvironment, activates and recruits T cells, and remodels the tumor immune microenvironment, converting immunologically "cold" tumors into immunologically "hot" tumors. On this basis, PD-1 inhibitors can fully exert their effect, releasing the T cell brake and achieving potent and durable tumor clearance, providing a novel pathway to overcome primary non-response and acquired resistance.
From a market perspective, this combination therapy targets the millions of patients worldwide with newly diagnosed and drug-resistant colorectal cancer, liver cancer, and other solid tumors each year. Particularly in high-incidence regions such as China, the clinical need is extremely urgent and substantial. According to OYResearch data, the global market for PD-1 and PD-L1 inhibitors reached $56.98 billion in 2024 and is expected to grow to $137.77 billion by 2031, representing a compound annual growth rate (CAGR) of 12.7% during the period 2025-2031. This vast and rapidly growing market still has significant room for truly effective innovative combination therapies.
Notably, Azvudine has already been approved in China for the treatment of HIV and COVID-19, with its clinical safety and tolerability well validated, laying a solid foundation for its clinical translation into the oncology field. If this combination therapy is successfully launched in the future, it will not only fill the immunotherapy gap for difficult-to-treat tumors such as MSS colorectal cancer but also has the potential to be expanded to multiple solid tumor indications, reshaping the treatment landscape for advanced-stage cancers.