This week’s World Federation of Hemophilia World Congress in Orlando, FL, where researchers gathered to present the latest updates in treatments for the chronic bleeding disorder, marked the latest step in a journey that dates back more than two decades for one particular treatment: gene therapy.
Gene therapy provides the potential of a long-term treatment for hemophilia patients, who have damaged or absent copies of the genes for so-called clotting factors and so rely on frequent infusions of those proteins to prevent dangerous and painful bleeds.
Experimental gene therapies designed to provide patients with working copies of the missing clotting factor genes around the turn of the century weren’t successful, but a newer group of treatments have slowly worked their way into clinical testing over the past few years. The current generation of therapies have produced the type of early results—in handfuls of patients—that got scientists excited about gene therapy in the first place. Gene therapies for hemophilia B, and recently the far more common hemophilia A, have shown the ability to help patients produce “meaningful” levels of the clotting proteins Factor IX and Factor VIII, respectively—more than 5 percent of the levels found in normal patients, which many view as the minimum bar for success—over the course of several months, without any significant safety problems.
Having even 5 percent of the normal amount of Factor VIII or IX can turn a severe hemophilia case into a mild one, but some experimental gene therapy treatments are helping patients produce far more than that. Some patients on therapies from BioMarin Pharmaceutical (NASDAQ: [[ticker:BMRN]]) and Spark Therapeutics (NASDAQ: [[ticker:ONCE]]) are producing upwards of 50 percent of normal levels of the clotting factors.
Still, it’s important to keep these data in perspective. Each clinical update at this week’s meeting is from a small number of patients in early-stage trials. Much more follow-up is needed, and in many more patients, in further trials, to understand who will respond to treatment and for how long.
The durability of treatment is critical to the economic case these treatments will have to make, particularly given their likely sticker-shock inducing cost. On the safety side, it’ll be important to watch going forward if the immune responses triggered by these gene therapies are as benign and controllable as they’ve been so far. Immune reactions to gene therapy can also stifle its effects.
So which company might be the first to prove its gene therapy offers durable, safe treatment for hemophilia? BioMarin and Spark are seen as the early leaders in gene therapies for hemophilia A and B, respectively, but their treatments likely won’t work for all patients, leaving the door open for alternative approaches from the likes of UniQure (NASDAQ: [[ticker:QURE]]), Dimension Therapeutics (NASDAQ: [[ticker:DMTX]]), Shire (NASDAQ: [[ticker:SHPG]]) (which now owns Baxalta’s hemophilia gene therapy work), and Sangamo BioSciences’ (NASDAQ: [[ticker:SGMO]]).
With that, here are the latest updates from the gene therapy players to present at the WFH’s meeting this week.
—BioMarin was the first company with
