HexaPro will be delivered using the company’s high-density microarray patch (HD-MAP).
Vaxxas holds an exclusive license from The University of Texas at Austin (UTA) to the SARS-CoV-2 spike subunit vaccine, HexaPro, for vaccination using a patch.
The Phase I clinical trial is being conducted in Australia at the University of the Sunshine Coast’s Sippy Downs clinical research location.
Under evaluation are the safety, tolerability, and immunogenicity of the vaccine candidate. The trial will involve 44 healthy adults, aged 18 – 50 years inclusive, who have had three doses of an authorized COVID-19 vaccine, with the last dose at least four months prior to participating in the study.
In addition to demonstrating the safety of the needle-free vaccine, the trial is designed to gather signals related to antibody and T-cell responses to dosing with the patch delivered candidate.
“This is our first trial of this promising vaccine patch. We are starting at very low dose with no adjuvants which we know are used regularly with vaccines to stimulate a greater immune response,” said Vaxxas CEO, David L Hoey.
“As such, the primary endpoint is safety. If the vaccine proves safe, we have a lot of flexibility to increase the dose or supplement the vaccine with an industry standard adjuvant or even mRNA delivery on the patch in future trials if we need or wish to drive an even greater immune response.”
Preclinical data
A second-generation SARS-CoV-2 spike protein, HexaPro, is optimized to be effective against major SARS-CoV-2 variants.
The company said preclinical research published in Science Advances and Vaccine and undertaken with The University of Queensland and collaborators demonstrated that HexaPro delivered using Vaxxas’ HD-MAP resulted in enhanced virus neutralizing antibody and T-cell responses against all known variants of concern, including alpha, beta, gamma, delta, and omicron, when compared to needle and syringe vaccination with HexaPro.
“We are pleased to see our COVID-19 patch transition from the lab to Vaxxas for Phase I clinical trials,” said Dr David Muller from The University of Queensland.
“Our work demonstrated that this COVID-19 patch, when tested in mice, produces potent immune responses against every SARS-CoV-2 variant we tested, including delta and omicron in preclinical models. If these results translate to humans, this patch could be a great tool in the fight against COVID-19,” he added.
Speaking to BioPharma-Reporter in September, Hoey said the HD-MAP platform can be used with any vaccine. Beyond this Phase 1 COVID-19 clinical trial, he said the developer has had more than 300 participants spanning three phase I studies to date (2 x seasonal influenza, 1 x measles-rubella). “In preclinical models, we’ve worked with vaccines for more a dozen disease indications and many different types of vaccine constructs. Much of this work is peer-reviewed and published.”
How do the patches work?
The HD-MAP has thousands of micro-projections about 250-300um in length that Vaxxas coats with the vaccine.
“When applied to the skin, the micro-projections deposit the vaccine antigen directly and intimately amongst dense populations of immune cells that reside in the skin. These immune cells capture the vaccine antigens and traffic them to the lymph nodes for processing. We are essentially delivering the vaccine directly to the lymphatic system, whereas, with needle/syringe injection, the vaccine antigens injected into muscle have a much more circuitous route to get to a lymph node, for generation of response,” continued Hoey.
Vaxxas has a large project underway with the US government focused on pandemic influenza. “We also have a relationship with Merck, working on a key vaccine; and for the Bill and Melinda Gates Foundation, we are advancing clinical development of a measles-rubella HD-MAP into phase II next year. We’ll be announcing some new ‘global’ relationships over the next few months,” added the CEO.
Improving pandemic and routine vaccination
The vaccination technology has the potential to fundamentally improve pandemic and routine vaccination, he said. “In areas such as pandemic preparedness/response, the HD-MAP can add extraordinary value by accelerating vaccination speed.”
Vaxxas is already working with the US government in that respect, and the company is also holding discussions with other governments on the same topic.
“Similarly, in lower-and-middle income countries, as HD-MAP vaccines can be stable outside cold-chain refrigeration and can be applied with low-skill, they can extend the reach of vaccines significantly. However, products sold into these markets are at extremely low margins, so clinical and CAPEX investment needs to come from global-health bodies.
“We believe that in high income countries, over time, skin-delivery of vaccines will become the standard. Based on the underlying science, it doesn’t actually make sense to use needle/syringe intramuscular delivery. And certainly, from a marketing perspective, most people will overtly prefer a patch to needle-syringe injection.”
