Concert hit with alopecia drug delay as FDA puts it on clinical hold

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The company says it will file the requested data quickly.

Concert Pharmaceuticals' just-started phase 2a trial of its baldness candidate CTP-543 has been halted by an FDA request to look at preclinical toxicity data.

The Lexington, Massachusetts-based biotech says the agency wants to see nonclinical toxicology studies and hasn't cited a safety concern. However, it wants to review the data as "support for the one-year dosing duration" that Concert is planning for its study of the drug in patients with alopecia areata, an autoimmune cause of baldness that affects up to 650,000 Americans at any time.

Concert—which specializes in improving the profile of drug molecules by modifying them with deuterium—reported phase 1 data on CTP-543 last December which showed the drug was well-tolerated across the three doses tested, but indicated last month its planned trial could be delayed by a "late-emerging clinical tablet appearance issue."

That issue has since been resolved, but it remains to be seen how long the latest FDA action will hold up the program. The news has given investors the jitters, however, with shares in Concert down more than 11% premarket albeit on light trading.

"At the request of the FDA, the company intends to submit the requested non-clinical study reports promptly," it said in its statement. "By regulation, the FDA has 30 days from receipt of Concert’s response to notify the company whether the clinical hold is lifted."

CTP-543 is an orally administered, deuterated form of the JAK inhibitor ruxolitinib. The drug is already sold as Jakafi for blood disorders by Incyte, which has filed a patent challenge against Concert over its intellectual property for CTP-543.

Incyte isn't actively looking at oral ruxolitinib for hair loss, but it does have an ongoing phase 2 study of a cream formulation of the drug in alopecia areata, according to clinicaltrials.gov. Oral ruxolitinib has been tested in an investigator-led trial at Columbia University, however, which showed that a dose of 20 mg twice daily resulted in significant hair regrowth in 75% of patients with moderate-to-severe alopecia areata.

Concert had been riding high at the moment thanks to a well-received agreement with Vertex for its revamped version of the latter company's cystic fibrosis therapy Kalydeco (ivacaftor) that gave it $160 million in cash and another $90 million in possible milestone payments.

One of the primary benefits of that deal, according to analyst Adam Walsh of Stifel, was to give Concert leeway to focus its energies on its alopecia drug, which he said at the time was an "underappreciated asset."

Deuterated molecules are emerging as a new therapeutic category, and one drug is already on the market, namely Teva’s Austedo, which was cleared by the FDA for movement disorders and Huntington's disease last month.