Biotechs jockey for gene therapy lead with hemophilia data ‘snapshots’

Generally it takes a readout from a completed trial to gain any important insights into the potential of an experimental drug. Unless you’re in a field like gene therapy, where the responses of even tiny numbers of patients are used to grab the spotlight in a market that’s seemingly insatiable for news. Add in a horse race environment on the data front, with competitors looking to establish a clear lead in a hot field, and the rivalry heats up on a patient-by-patient basis.

Enter Spark Therapeutics, which is making a bid to become the first gene therapy company to pitch a product to the FDA.

On Thursday, Spark--which is partnered with Pfizer ($PFE)--trotted out data on three hemophilia B patients enrolled in a Phase I/II study. Hemophilia patients are at risk of uncontrolled bleeding because they lack a clotting agent known as Factor IX. And following gene therapy with SPK-9001, they demonstrated Factor IX levels of 28%, 30% and 16% of normal. Those were the numbers that went into an abstract ahead of a June 11 presentation at a meeting of the European Hematology Association, and the biotech achieved considerable attention for the results with a release and media outreach.

As a result, its stock ($ONCE) surged 15% by the end of the day.

One of the reasons why it scored is because the numbers beat out a competitor. UniQure ($QURE) played this game back in January, when it noted that two hemophilia B patients had Factor IX expression levels of 5.5% and 4.5%. Like Spark, uniQure claimed a success, highlighting historical data that suggest 5% is the mark you need to hit to demonstrate a meaningful impact for patients. At Spark, the historical number to beat is 12%.

All the data are intriguing, and none of them are conclusive. Historical comparisons in lieu of a control arm can be controversial and frequently conflicting. Gene therapy in particular will be priced high on the notion that one treatment could provide long-term results, if not a cure. But there’s little insight on durability from preliminary data. And there’s no telling if the final readout will be anywhere near as promising as the snapshot.

This is also a crowded field, with each player looking to distinguish itself. Biogen ($BIIB) focused on hemophilia A and B early, bringing in pioneer researcher Olivier Danos to run its fast-growing gene therapy group. Baxalta released early data on BAX 335 last year, while Dimension Therapeutics may be the next company with early data to report. And BioMarin ($BMRN) has been making early tracks with its hemophilia A gene therapy effort.

For BioMarin, which has claimed a leading role in hemophilia A with the first program in the clinic, the snapshot proffered a few weeks ago includes 6 patients who had achieved Factor VIII expression over 5% (their bar for success), with two over 50%.

This is one race that’s just going into its first turn, but the jockeying is already intense.


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