Dr. Paul Liu is the co-founder and executive chairman of PAX Therapeutics, a life sciences startup developing technology to facilitate a new, nonsurgical treatment for tendon and ligament injuries. He also serves as chair and professor of plastic surgery at Brown University.
PBN: What is PAX Therapeutics, and what type of treatment is it developing?
LIU: PAX Therapeutics spun out of Brown University/Rhode Island Hospital to more rapidly develop a novel therapy to optimize the healing of tendons and ligaments following injuries. These range from ACL tears during sports to tendon ruptures caused in kitchen accidents, from professional athletes to ordinary people going about their everyday activities. Surgery helps, but often people are left with pain, limited function or outright disabilities. PAX is developing the delivery of a gene, much like for various vaccines or gene therapy for diseases, that optimizes the healing after surgery to be faster, stronger and with fewer adhesions – less stiffness, less pain.
PBN: What makes this type of treatment different from existing therapies?
LIU: Existing therapies are basically surgical, either stitching the tendon back together or taking a ligament from another joint or a cadaver to replace the torn one. But the surgery has drawbacks, including needing to immobilize the joint for a long time, scar tissue that forms limiting the joint movement and causing pain, or even re-rupture of the tendon after surgery, leaving the person disabled.
This treatment delivers a gene coding for a growth factor into the cut end of the tendon during the repair surgery; the growth factor results in the proper type of collagen doing the healing instead of the type of disorganized, weaker collagen that forms scars. The gene for the growth factor is delivered by a harmless virus that itself doesn’t cause diseases, and which only produces the growth factor for a matter of weeks.
PBN: Why did you decide to focus on flexor tendon injuries of the hand, and in what way can this type of injury typically affect someone's day-to-day life?
LIU: Our initial target is hand flexor tendon injuries because of the huge medical need for an improvement to existing standard of care surgery, with many people slicing their tendons not just in industrial accidents but while cooking.
“Avocado hand” has been on the rise from people cutting their tendons while making guacamole. Cutting bagels is another source of cut hand tendons. The re-ruptures following surgery and the disability from not regaining full use of the hand and fingers should be improved based on results from studies we have done in a relevant animal model. But of course, the technology may be more broadly applicable to other tendons and ligaments.
PBN: What are the next steps for PAX Therapeutics? Do you have a goal for when it could become a broadly available treatment?
LIU: We have already started “standard of care” clinical trials at Yale and will soon add Rhode Island Hospital to establish the exact protocol for therapy and documenting improvement in strength and finger flexion following current hand tendon repair surgery. This means that our Phase I clinical trial testing our product candidate will be able to be compared against existing data so that we will get an indication of efficacy even in the first phase of human testing, rather than having to wait until Phase II or Phase III studies further down the road. We also will expand our efforts to use the technology for horses – who currently get euthanized after such tendon injuries – and dogs, who have ligament tears similar to ACL tears.
PBN: As a life sciences startup, has PAX Therapeutics been influenced by the state's ongoing push to establish the R.I. Life Science Hub? If so, in what ways?
LIU: We hope to be a part of the R.I. Life Science Hub to participate in a vibrant biotech community of home-grown, cutting-edge science providing new treatments for unmet medical needs and to showcase the incredible science in Rhode Island.
The hub would enable us to develop our next clinical candidate therapies more rapidly through the provision of space and shared resources in a more cost-efficient manner than would be feasible on our own. Such a hub means that the energy and funds of the startups can be more effectively focused on developing the needed treatments, rather than on building separate infrastructure for each small company. We are following the build by Ancora of incubator space very closely.
Jacquelyn Voghel is a PBN staff writer. You may reach her at Voghel@PBN.com.
