Teva’s Huntington drug launch on hold after FDA rejection

Brain imaging

Teva’s $3.5 billion plan to buy Auspex and take the final slap shot needed for a new drug approval has gone awry. The company says that the FDA has rejected its marketing application for SD-809 for chorea, the involuntary motion that afflicts Huntington’s patients.

At the time of the buyout in the spring of 2015, when the biotech boom was in full swing, Teva ($TEVA) said it expected to launch the drug this year. Instead, it will now circle back to examine “certain metabolites” found in patients. The company emphasized that the FDA had not demanded any new trials, which would have seriously derailed any approval timeline.

As it stands, investors are left wondering what went wrong. SD-809 is the first deuterated product to go in front of the FDA. With this reengineering process, investigators take an existing drug, in this case tetrabenazine (Xenazine) and redesign it to break down more slowly, a tweak which should make it possible to provide lower dosing for maximum effect. 

Theoretically, that simple tweak was also intended to de-risk the development of the drug. But that approach hasn’t worked for Teva, which has experienced a string of setbacks in the clinic in recent years as it tries to improve the efficiency of its R&D side of the business.

The therapy--deutetrabenazine--is a small molecule inhibitor of vesicular monoamine 2 transporter, or VMAT2, which is designed to regulate the levels of dopamine in the brain. The same metabolites appear in patients who take either deutetrabenazine or the original tetrabenazine, according to Teva.

This is the second key late-stage drug to jump the tracks for a pharma buyer in a matter of days. AstraZeneca ($AZN) shocked many of its investors last week with the news that the FDA rejected its hyperkalemia drug ZS-9, picked up in the $2.7 billion ZS Pharma buyout last year.

“Teva will continue to work closely with the FDA to bring SD-809 to the market as quickly as possible,” said Michael Hayden, president of global R&D at Teva. “We know that many people in the HD community are waiting for this new medicine. We understand there are very limited treatment options for HD patients and their families, hence we are accelerating the re-analysis process we were asked to conduct. We plan to submit our response to the CRL in Q3 2016."

- here's the release

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