Altimmune has announced the discontinuation of its intranasal COVID-19 vaccine program following disappointing Phase 1 trial results, marking a significant setback in the development of alternative vaccine delivery methods.
The US biotech company reported that its AdCOVID candidate failed to generate sufficient immune responses in early clinical testing. While the vaccine demonstrated the ability to produce antibodies that could bind to and neutralize the SARS-CoV-2 spike protein, both the quantity of antibodies and the number of responding patients fell below expected thresholds.
Clinical Trial Challenges and Technical Details
The trial faced initial hurdles when the FDA implemented a clinical hold, requiring modifications to the study design and additional manufacturing information before allowing the study to proceed. The subsequent trial results contradicted promising preclinical data that had previously supported the program's advancement.
Dr. Scot Roberts, Chief Scientific Officer at Altimmune, offered insight into the unexpected results, noting a key difference from their successful NasoVAX influenza vaccine trials: "Unlike the NasoVAX study, the AdCOVID study population lacked immunity from prior infection or vaccination. We believe that prior immunity in humans may be important for a robust immune response to intranasal dosing."
Strategic Implications and Market Impact
The news triggered a sharp decline in Altimmune's stock price, as investors expressed concerns about potential implications for the company's broader intranasal vaccine platform. In response to the setback, CEO Vipin Garg announced a strategic pivot, with the company now concentrating resources on ALT-801, their peptide-based drug candidate targeting non-alcoholic steatohepatitis (NASH) and obesity.
Landscape of Intranasal COVID-19 Vaccine Development
Despite Altimmune's withdrawal, several other organizations continue to pursue alternative delivery methods for COVID-19 vaccines. Notable efforts include:
- Oxford University's research into nasal delivery systems
- Imperial College London's investigation of inhaled versions of their saRNA-based vaccine and the AstraZeneca/Oxford vaccine
- CanSino Biologics' initiated trials of an inhaled vaccine formulation
- Ongoing development by companies including Cadogenix, Phage Novo Bio, Precision Virologics, and Immune System Regulation (ISR)
The initial promise of Altimmune's nasal vaccine centered on potential advantages including room-temperature stability for easier distribution and the possibility of enhanced mucosal immunity at the virus's primary entry point. These potential benefits made the development particularly attractive as an alternative to traditional injectable vaccines.
