Bilex Pharma today announced positive topline results from the Phase 1 clinical trial of BLX-DEN01, its tetravalent dengue vaccine candidate. The study demonstrated that BLX-DEN01 was well-tolerated and, crucially, induced balanced neutralizing antibody responses against all four dengue virus (DENV) serotypes (DENV-1, DENV-2, DENV-3, and DENV-4).
Addressing a Major Challenge in Dengue Vaccine Development
Dengue fever is a significant global health threat, endemic in over 100 countries and putting nearly half the world’s population at risk. A major challenge in developing dengue vaccines stems from the existence of four distinct virus serotypes. Immunity against one serotype can, in some cases, increase the risk of severe disease upon subsequent infection with a different serotype – a phenomenon known as antibody-dependent enhancement (ADE). Therefore, an effective dengue vaccine must induce strong and balanced protective immunity against all four serotypes simultaneously to avoid potentially increasing disease severity.
Achieving this balanced tetravalent response has been a persistent hurdle in the field. The results from the BLX-DEN01 Phase 1 trial suggest Bilex Pharma’s approach may successfully address this critical requirement.
Phase 1 Trial Highlights
The randomized, placebo-controlled Phase 1 study evaluated the safety, tolerability, and immunogenicity of BLX-DEN01 in healthy adult volunteers in the UK. Key findings include:
- Balanced Tetravalent Neutralizing Antibodies: Participants vaccinated with BLX-DEN01 developed neutralizing antibodies against all four dengue serotypes. Importantly, the antibody levels were comparable across all four serotypes, indicating a balanced immune response profile.
- Robust Immunogenicity: High levels of neutralizing antibodies were observed after the vaccination schedule.
- Favourable Safety Profile: BLX-DEN01 was generally well-tolerated, with no serious adverse events related to the vaccine reported. Most adverse events were mild to moderate and transient, consistent with expected reactogenicity for similar vaccine platforms.
“Demonstrating a balanced immune response against all four dengue serotypes in this first-in-human trial is a pivotal achievement for our BLX-DEN01 program,” said Dr. Sophia Chen, Chief Medical Officer at Bilex Pharma. “This specific outcome addresses one of the most significant historical challenges in dengue vaccine development and gives us strong confidence as we plan for further clinical evaluation.”
Innovative Viral Vector Approach
BLX-DEN01 utilizes an innovative viral vector platform engineered to deliver optimized antigens representing all four dengue serotypes. This approach is designed to present the antigens to the immune system in a way that promotes balanced recognition and response.
“Our scientific teams specifically designed the BLX-DEN01 construct and delivery strategy to overcome the immunodominance issues that have complicated previous tetravalent dengue vaccine efforts,” explained Dr. Eleanor Harrington, Chief Scientific Officer at Bilex Pharma. “Seeing this balanced profile emerge in the Phase 1 clinical data provides encouraging validation of our rational design approach.”
Part of Project SAFEGUARD
The BLX-DEN01 program is a key component of Bilex Pharma’s Project SAFEGUARD, a strategic initiative focused on developing vaccines against mosquito-borne and neglected tropical diseases prevalent in low- and middle-income countries.
“Dengue imposes an enormous burden on health systems and economies in endemic regions,” stated Dr. Andras Ottlik, CEO of Bilex Pharma. “These positive Phase 1 results, particularly the balanced tetravalent immunity, mark an important step towards developing a potentially transformative tool for dengue prevention. This progress reinforces our commitment within Project SAFEGUARD to apply cutting-edge science to pressing global health needs.”
Next Steps in Development
Based on these encouraging Phase 1 results, Bilex Pharma is planning to advance BLX-DEN01 into Phase 2 clinical trials. These studies will be conducted in dengue-endemic regions to evaluate safety and immunogenicity in populations with prior dengue exposure and to further assess the durability of the balanced immune response.
“We are now actively planning the Phase 2 program, engaging with clinical investigators and regulatory authorities in dengue-endemic areas,” added Dr. Chen. “The data from Phase 1 provide a solid foundation for designing studies that will further characterize BLX-DEN01’s potential in the populations most affected by dengue.”
Potential Public Health Impact
An effective, safe, and easily deployable tetravalent dengue vaccine could significantly reduce the global burden of dengue fever, preventing millions of cases and reducing pressure on healthcare systems in endemic countries. The balanced immune profile observed with BLX-DEN01 offers hope for a vaccine candidate that could provide broad protection without the theoretical risk of enhancing disease severity.
Bilex Pharma remains committed to advancing BLX-DEN01 through rigorous clinical development, collaborating with global health partners to ensure that, if successful, this vaccine can reach the populations who need it most.
About Bilex Pharma
Bilex Pharma is a UK-based biotechnology company dedicated to advancing human health through groundbreaking research and innovative vaccine development. Our mission is to protect communities worldwide by combating infectious diseases and emerging health threats with safe, effective, and accessible vaccines, leveraging cutting-edge platforms including mRNA, viral vectors, and advanced adjuvant systems.
About Dengue
Dengue is a mosquito-borne viral infection found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas. It is transmitted by Aedes mosquitoes, primarily Aedes aegypti. Dengue causes a wide spectrum of disease, from subclinical infection to severe flu-like symptoms. Severe dengue (previously known as Dengue Haemorrhagic Fever) is a potentially lethal complication, characterized by plasma leakage, fluid accumulation, respiratory distress, severe bleeding, or organ impairment. There are four distinct, but closely related, serotypes of the virus (DENV-1, DENV-2, DENV-3 and DENV-4). Recovery from infection by one provides lifelong immunity against that particular serotype, but subsequent infections by other serotypes increase the risk of developing severe dengue.