Gene Therapy Advances, But Hemophilia Is No Easy Target

Xconomy National — 

Mark Skinner, the former longtime president of the World Federation of Hemophilia, has had the blood disease on his mind his entire life.

He doesn’t have a choice.

Skinner, 57, was born with a severe form of hemophilia A, meaning he has a tiny fraction of the necessary cellular machinery to clot blood. His disease dictates what he can or can’t do every day. He’s had multiple orthopedic surgeries and years of joint damage. Over the course of his life he’s seen hemophilia go from a disease with very few treatments to a manageable condition, but one that, as he says, chronically “tethers” him to the healthcare system.

One would think Skinner would jump at the chance, then, to try gene therapy, which offers the potential for a one-time long-lasting treatment—if not an outright cure.

BioMarin Pharmaceutical (NASDAQ: BMRN) and Spark Therapeutics (NASDAQ: ONCE) are both developing gene therapies for severe hemophilia A patients just like Skinner. BioMarin’s treatment, featured last week in the New England Journal of Medicine, is headed for late-stage clinical trials.

If the product, known as Valoctocogene roxaparvovec, or val-rox, gains approval, Skinner and others like him might no longer have to inject themselves with drugs every other day to prevent dangerous bleeds—drugs that leave him with a $1 million bill every year. Maybe Skinner, who ran the WFH from 2004 to 2012 and still leads its U.S.-based affiliate, could wake up in the morning and never think about hemophilia again.

Yet Skinner says he won’t sign up, at least not yet. He is open to gene therapy, but concerned the treatment might not work for him, or might taper off down the road. “I don’t know when to say yes,” he says. “And a big part of that is predictability and certainty.”

Even drug-industry proponents acknowledge that the new technology doesn’t have a clear timeline. “At some point in the near future, hemophilia will be cured by gene therapy,” says Glenn Pierce, a former senior executive of Biogen’s hemophilia business, who worked on such gene therapies at Avigen over a decade ago. “The question is when that will happen.”

Skinner’s hesitancy provides a cautionary tale amidst the excitement gene therapy is generating. Experimental therapies for hemophilia A and the less common hemophilia B have shown, in some cases, a stunning ability to help people with severe hemophilia produce enough clotting protein to prevent dangerous and damaging bleeds.

The results for a small handful of patients extend beyond a year. No major safety problems have emerged so far.

Crucial questions remain unanswered, however: How will people respond to treatment? Will patients still need supplemental clotting factor on top of the gene therapy? Will treatment effects wear off—especially with children—and if so, will anyone be eligible for a second dose?

“In the real world there are an awful lot of patients that the gene therapy may not be a candidate for,” Skinner says.

All these questions are opening a window for … Next Page »

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