Tiny vaccine delivery patches could solve logistical challenges, but they face manufacturing hurdles. Here’s how Vaxxas is trying to overcome them.Merck (NYSE:MRK) and Vaxxas announced earlier this year that the pharmaceutical giant was using Vaxxas’ High Density Microarray Patch (HD-MAP) platform as a delivery platform for a vaccine candidate.
Vaxxas did not disclose what type of vaccine the patches might deliver and Merck declined to reveal it. But Merck is very much in the race to create a vaccine to protect against the virus that causes COVID-19.
Meanwhile, German manufacturing equipment maker Harro Höfliger has agreed to help Vaxxas (Cambridge, Mass.; Sydney, Australia) develop a high-throughput, aseptic manufacturing line to make vaccine products based on Vaxxas’ HD-MAP technology. Initial efforts will focus on having a pilot line operating in 2021 to support late-stage clinical studies with a goal of single, aseptic-based lines being able to churn out 5 million vaccine products a week.
Based on technology originally developed at the University of Queensland, Vaxxas’ HD-MAP includes a 9-by-9 mm array of thousands of very short projections around 250 microns in length. Invisible to the naked eye and coated with vaccine, the projections can quickly deliver vaccine to immune cells. Vaxxas officials claim the technology can deliver vaccine more efficiently than a needle and syringe.
The patch comes in a hockey-puck-shaped applicator with a foil seal. The patch is anchored on a serpentine ring with a powerful dome spring behind.
Drug Delivery Business recently interviewed Vaxxas CEO David Hoey about the patch technology and how it could improve vaccine delivery.
DDB: What kinds of challenges did you have to overcome to make the HD-MAP technology a reality?
Hoey: Microneedles have been around for maybe 2 decades, but there are no products on the market. That’s a big question. The challenge from microneedle patches has not been so much that the immunological results haven’t been compelling, because there are hundreds of papers out of all sorts of institutions and companies that show that if you can deliver a vaccine effectively into the skin, you can get a much better immunological result.
Where it gets tricky is if you take it away from being a science experiment and you have to start to impose sterile manufacturing requirements that you need for clinic. And how do you actually manufacture these things at an industrially relevant scale? So that ends up being the most challenging part of the entire equation. We’ve focused very, very heavily since inception on making sure that every one of the individual components that make up the device is manufacturable by technologies that are industrially scalable, and then they can come together in a system that will enable sterile production at a relevant scale.
DDB: How is Harro Höfliger helping with manufacturing?
Hoey: The work that we do is focused on making these device components and the design. The work that Harro is doing is how we get sort of the high-speed robotic handling of the individual components as they make their way through the aseptic line. We have to do a 100% [quality control] of integrity. So the patch has to be visually inspected to make sure that those thousands of projections are intact. We then have to dose vaccine onto the patch with the printing technology. And we then have to verify that the vaccine was printed onto the tips of the projections, not the base.
So we have a whole series of QCs that are associated with any sort of medical product. The trick is, ‘How do you do that at line speed?’ And line speed for us is about 600 patches per minute. A production line could do about 5 million a week. So all of those steps you’re doing, you have to be able to do them in a fraction of a second. That’s the work with Harro. We’ve built a proof of concept line in Germany that shows that we can do the handling at that speed. We’re now bringing that proof of concept line into our labs. It’s the first step toward the pilot line.
DDB: What kinds of advantages could HD-MAP have as a vaccine delivery method amid a pandemic?
Hoey: There are elements of the patch that make it ideally suited to build onto the greatness that is a vaccine. In the influenza vaccine study that we published a few months ago, we showed that going down to one-sixth of a dose of the vaccine on the patch produced the same result as full dose by needle and syringe. And so in a pandemic context, you can produce many more doses of the vaccine more quickly from the limited vaccine stocks. Once the vaccine is printed on the patches, it’s in a dry format, and the flu vaccine was stable for 12 months at 40 °C (104 °F) and we only went out to 12 months. You can have a device that essentially could make many more doses more quickly in a pandemic response. You’re able to use logistics like U.S. Postal, FedEx or UPS to distribute to homes where people could do self-administration. Self-administration is something that we were actually interested in examining pandemic aside in our next flu study.