Zafgen obesity drug scores heavyweight success in PhII trial

Zafgen has followed up promising results from early-stage work on its weight drug beloranib with a stellar Phase II study that tracked rapid weight loss among the severely obese, with one group shedding an average of 22 pounds in 12 weeks. CEO Tom Hughes says the mid-stage success clears a path to a Phase IIb trial that can fine-tune the dose while taking more time to gauge the long-term impact of its treatment on weight. And the data harvest sets the right tone for ongoing talks with investors about a new financing round for the biotech.

Investigators tracked progressive weight loss among the obese patients in the study, says Hughes, with the dose-ranging trial spurring average weight loss of 11 pounds at the low dose to close to twice that amount for the high dose. The placebo arm's average weight loss fell short of a pound. Hughes says the drug was able to do that with no signs of serious adverse events while tracking a drop in blood pressure and no change in heart rate--"which is very, very good to see."

Right now the sweet spot on dosing looks to be 1.2 mg--right in the middle of the range studied in the Phase II. That number could get pushed to 1.8 mg, and Hughes adds that they haven't given up on the high 2.4-mg dose, which triggered the greatest amount of weight loss.

As dosing ranged higher, says Hughes, patients complained more about insomnia, causing some to drop out of the study. But that high dose also triggered results comparable to surgical intervention--the kind of dramatic and fast weight loss that spurred the Zafgen team's excitement about their prospects. With that kind of weight loss, a manageable amount of sleep loss could prove to be an acceptable tradeoff for the severely obese, says the CEO.

The drug works by blocking the methionine aminopeptidase 2, or MetAP2, enzyme--which plays a role in the body's production and use of fatty acids. The drug knocks off weight by dialing down the amount of fat produced by the body, a completely different approach from the current crop of drugs, which is designed to suppress appetite.   

The next step for Zafgen is to push ahead with a Phase IIb study next year that would run 6 to 12 months in a group of about 200 patients. That would allow investigators to fine-tune the dosing while studying long-term impacts on weight, blood pressure and glycemic control for diabetics. There's also an ongoing study for a small group of patients with Prader-Willi syndrome, an orphan indication for insatiable hunger, that should wrap later this year or early in 2014.

A pair of weight-loss drugs with a much more modest effect on weight has made it to the market recently. But Big Pharma stayed clear and sales, so far, have been limited.   

Zafgen is talking with investors now about raising more cash for the work ahead. Hughes says the next round should close "relatively soon." In the meantime, Hughes adds when asked about the chance of an IPO, the company is exploring all of its options. 

- here's the press release

Special Report: 2009 Fierce 15 - Zafgen

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