neurons in the central nervous system (the brain and spinal cord) can regenerate after being damaged, just like the nerves outside the CNS can. McKerracher wanted to know why. The theory was that a group of proteins blocked these cells from repairing themselves; stymie the activity of those proteins, and perhaps the nerves would grow back.
McKerracher’s group homed in on a signaling molecule called rho. She describes it as the “mastermind switch” that regulates the growth and regeneration of injured axons—the long thin nerve fibers that shoot electrical impulses out of a neuron. When CNS trauma occurs, she says, rho is “hyperactivated,” and various growth-inhibitory proteins stop axons from regrowing. McKerracher and her group developed a molecule—a modified version of the enzyme c3 transferase—to block rho and, in the process, all the proteins it controls, which hopefully will let new nerve fibers form.
McKerracher believes her master switch approach can work. Others have failed she says, because they have tried to knock out a single protein (Nogo, for instance), which leaves other inhibitory proteins in place.
Several companies today, such as StemCells Inc., Asterias Biotherapeutics (which has Geron’s old program), and Neuralstem, are working with stem cells as the therapy. McKerracher contends there are open questions to that approach, like when to actually deliver the cells. They can’t be given right after injury, for instance, because the immune system would kill them during the body’s inflammatory response to trauma.
“Plus a drug that’s sold in a bottle and can be available in every single trauma center to every single American is very different than an extremely expensive therapy that requires a special surgery to apply it,” she says.
McKerracher has been working on her rho-inhibiting drug since 2000, when she raised $12 million (Canadian dollars) to form the first incarnation of her company. In a trial that wrapped up in 2008, there were signs Cethrin was helping a small group of patients with spinal cord injuries recover some motor function.
But no work has been done since. BioAxone licensed Cethrin to Boston Life Sciences (later known as Alseres Pharmaceuticals) in 2007, and the financial crisis struck. Alseres focused elsewhere, and Cethrin was left behind. Regulatory filings from Alseres in 2009 show a dispute between the two companies about the drug’s progress.
“I decided I wanted to do something about it,” she says. “Quite frankly after so many years working in regenerative neuroscience, I still really deeply believe that Cethrin is the most promising drug to treat spinal cord injury.”
McKerracher cut a deal for the IP in 2011 (she declined to be more specific) and salvaged the drug. She founded a new company in Cambridge with a similar name, BioAxone Biosciences, and spent years trying to find a partner to take Cethrin forward. She says she wanted the right partner, and a deal with enough cash to let her develop other drugs dealing with nerve cell regeneration.
It’s now been seven years since Cethrin’s last trial and five since the new BioAxone was started.
“Five years seems odd to me,” Yee said via e-mail.
“These deals take a lot of time, and they take all of your energy,” McKerracher says. “When you have a small group and they’re working on a deal, that’s what gets done.” McKerracher and an individual she declined to name are BioAxone’s only investors.
Barber says Vertex didn’t make an announcement because “formulation work and regulatory discussions have been ongoing” since the deal was struck, and it “wanted to communicate about the VX-210 program when we had further clarity on the development program and next steps.”
Vertex expects to provide those details when it starts the next trial of the drug later this year, he says.
