Zafgen drug registers rapid weight loss in early-stage study

Undaunted by the FDA's ever-rising safety bar for obesity drugs, Cambridge, MA-based Zafgen today partially pulled back the veil from some early-stage data on its lead weight drug, demonstrating that it has the potential to trigger significant weight loss in a matter of weeks.

Backed by two aggressive venture groups, Third Rock and Atlas Venture, Zafgen says that its Phase Ib study of ZGN-433 triggered an average loss of 1 kilogram (2.2 pounds) a week during the one month study. Investigators studied the drug--which targets fat metabolism--in 24 people. A Phase IIa study is scheduled to launch later this year as the biotech attempts to prove it has a drug that can rival the effects of bariatric surgery.

"The results show the magnitude of weight loss approaches the commonly recommended maximal rate of safe weight loss, which is exceeded only by gastric bypass surgery, duodeno-jejunal bypass liner and restrictive therapy," says Zafgen CEO Tom Hughes (photo). "If sustained, the rate of weight loss would be consistent with a 6-9 month course of treatment in individuals requiring a 20-40 percent reduction in weight."

Zafgen, which has raised about $30 million so far, obviously has a very long way to go before it can make its case to regulators. And if it can make the distance, it will still face a very tough regulatory crew. Three companies mounted ambitious efforts in 2010 to win FDA approval of new weight loss drugs. But so far only one of the drugs has been endorsed by an FDA expert panel. Advisors to the agency have been extremely leery of any signs of safety issues related to the drugs. 

"I think it's been an amazing year in terms of education on this process," says the CEO, one of only three fulltime staffers at the virtual biotech, a 2009 Fierce 15 company.

"I think one of the biggest things we've learned is that obesity treatments need to be supported by a very carefully crafted REMS (Risk Evaluation and Mitigation Strategies) program," Hughes tells FierceBiotech. "You need to have a way of understanding who is getting the drug, if it's used appropriately and if it isn't working that it isn't continuing to be prescribed. Orexigen showed they had learned a lot from the prior advisory committees. They came prepared with a well considered REMS strategy. That made a big difference."

The next 18 months is likely to prove pivotal for Zafgen as it moves into mid-stage development, with possibilities for a partnership, a potential buyout or more venture funding. "We need to decide this year whether we partner or allow ourselves to be bought or fund the next cycle," says Hughes. Zafgen may even hire two more workers, almost doubling the staff.

- check out the Zafgen release