The California-headquartered biotech, which develops oral vaccines administered by tablet rather than injection, says a COVID-19 vaccine in this form would be ‘significantly’ easier and cheaper to store and distribute as it does not require a refrigerated cold chain like most injectable vaccines.
Having obtained the green light from the U.S. Food and Drug Administration (FDA) in its IND application, announced yesterday, enrolment for the Phase 1 clinical trial will begin this month with results anticipated in early 2021. It is the first oral tablet vaccine for COVID-19 to reach human clinical trials.
Vaxart’s COVID-19 vaccine is using the same platform technology as its more advanced influenza vaccine program, which released topline data from a Phase 2 challenge study earlier this year.
‘We made the strategic decision to pivot our focus to COVID-19’
Vaxart's focus is on developing tablet versions of currently marketed vaccines, as well as designing recombinant vaccines for new indications. All are based on its oral Vector-Adjuvant platform, VAAST.
Development programs include tablet vaccines for norovirus, seasonal influenza, and respiratory syncytial virus (RSV). The company has also a development program for a therapeutic vaccine for human papillomavirus (HPV), Vaxart’s first immune-oncology indication.
At the start of this year, Vaxart started working on its coronavirus vaccine.
“In January, we felt a “call to duty” and made the strategic decision to pivot our focus to combatting COVID-19 using our proprietary vector platform,” Vaxart’s chief scientific officer, Sean Tucker Ph.D., told BioPharma-Reporter.
“We recognize that our technology could offer potentially superior efficacy as well as an ideal avenue for distribution and a comprehensive solution for this global pandemic.”
The Phase 1 trial will be an open-label, dose-ranging study conducted in healthy adults aged 18-55 years old. Its primary objective will be to examine the safety and reactogenicity of two doses of the vaccine. Secondary objectives include immunogenicity, duration of immune response and occurrence of symptomatic COVID-19.
Advantages of tablet vaccines: room temperature storage and no needles
Vaxart believes its new vaccine candidate may have several advantages over traditional injectable vaccines in the fight against COVID-19. As a tablet, it can be kept at room temperature and can be shipped and stored without the need for refrigeration. It also eliminates the risk of needle-stick injury; and does not need a trained healthcare professional for administration.
Patients would not need to travel to vaccination sites; and the tablet could be a more appealing method of vaccination for people who do not like needles.
In terms of production, Vaxart says its approach offers an efficient, standardized, high-yield manufacturing process. One of the biggest challenges for a COVID-19 vaccine comes from the need for large scale lyophilizers, said Tucker.
“The active agent in the vaccine is made in a similar process as the Oxford and Janssen vaccines by growing it up in large bioreactors.
“One key difference is that we dry our vaccine, which improves stability at elevated temperatures. To dry the vaccine we do need access to large scale lyophilizers. We announced an agreement to work with Attwill Medical Solutions to provide these large systems and solve this major challenge.
“Another advantage is that our vaccine does not require sterile fill and finish, a significant bottleneck for injectable vaccines. Our end product is very efficiently made using high throughput industrial tableting equipment under sanitary conditions.”
Vaxart's flu and COVID-19 programs: Technology and trials to date
Vaxart has ‘demonstrated that its proprietary tablet vaccine delivery platform is suitable to deliver recombinant vaccines, positioning it to develop oral versions of currently marketed vaccines and to design recombinant vaccines for new indications’.
The company has filed domestic and international patents covering its proprietary technology and creations for oral vaccination using adenovirus and TLR3 agonists.
Vaxart's VAAST platform (Vector-Adjuvant-Antigen Standardized Technology) uses a disabled Ad5 virus as its viral vector, recombinantly removing the DNA Ad5 uses for viral replication. Ad5 delivers the vaccine to the epithelial cells lining the mucosa of the small bowel.
H1 influenza
Vaxart’s most advanced program is its H1 influenza tablet vaccine, VXA-A1.1. A Phase 2 challenge study was published in The Lancet earlier this year.
“These showed the oral tablet had comparable efficacy to an active comparator, a traditional injected flu vaccine. Our tablet vaccine induces mucosal immunity, a potential key factor for improving influenza vaccine performance and reducing viral shedding/transmission,” said Tucker.
Vaxart has a universal influenza vaccine collaboration with Janssen.
COVID-19
Last week, Vaxart released preclinical data 'showing its oral COVID-19 vaccine candidate induces potent systemic and mucosal immune responses which may be crucial for effective protection against SARS-CoV-2 infection and transmission.'
“The data from these studies suggest that our vaccine candidate is capable of inducing immunogenicity on three levels: first, to induce potent serum neutralizing antibodies to the viral S protein, second to induce a mucosal immune response, and third to induce T cell responses,” said Tucker.
“As we continue to learn more about COVID-19, there is a growing body of evidence that mucosal immunity may become a key factor for the development of an efficacious vaccine. Both mucosal IgA and mucosal T cells have been shown to contribute to sterilizing immunity in other respiratory diseases. Importantly, while systemic immunity is important for controlling the development of illness, it has been suggested that mucosal immunity may be essential for blocking transmission which will be crucial for an effective vaccine campaign.
"We believe this will be essential in reducing infection rates and eventually eradicating COVID-19 globally.”
The non-peer reviewed study can be found here.
