efficiently as energy. That’s the new concept, anyway.
It’s more than an academic curiosity, as Zafgen is putting this notion to the test in its first clinical trial. The plan is to study ZGN-433 in about 40 obese women at a single site in Australia. The drug, an angiogenesis inhibitor, failed to shrink tumors in a cancer trial, but the compound had the unexpected side benefit of helping patients lose weight. Based on the animal studies the company has run to better understand the weight loss effect, Zafgen plans to try doses 100 to 500-fold lower than were envisioned when the molecule was a cancer treatment.
Hughes won’t say exactly what biological target on cells this drug is being aimed at, or which drug company used to own it. But this trial has been set up to give Zafgen a clear answer on whether the treatment—and the new weight loss concept—has a future.
The main goal, with any early-stage trial, is to see the drug is safe, well-tolerated, and properly absorbed into the body, Hughes says. These women are considered not just overweight, but significantly obese, with body-mass indexes of between 35 and 45. That means a person who is 5-foot-8 would have to weigh at least 230 pounds to enroll. They will be randomly assigned to get twice-weekly injections of the Zafgen treatment over a six-week period, or a placebo injection, according to this posting on clinicaltrials.gov.
Zafgen will be measuring how much weight these people lose in the trial, and taking important molecular measurements to see if the drug is hitting the intended target, and whether that correlates with its new theory of how the drug works. Data from the trial should be available by the second half of 2010, Hughes says.
The outcome will have to be startling for Zafgen to go forward. It’s not likely to be a drug for the masses who want to drop a few pounds. If effective, it will likely be a competitor for bariatric surgery. “It’s strong medicine for serious obesity,” Hughes says.
More specifically, Zafgen will need to show about an additional 20 percentage points of body weight loss beyond what patients get from a placebo, in a “reasonable” amount of time, Hughes says. That translates to about 70 to 100 pounds of weight loss for most obese people in about a nine-month period, he says. That’s far greater weight loss than has been seen from any of the experimental pills that are near the end of clinical development, from high-profile obesity drug developers like Arena Pharmaceuticals, Orexigen Therapeutics, and Vivus.
If Zafgen can reach its lofty goal later this year, it will be in position to raise more capital, or strike a partnership, Hughes says. If not, then it might be time for the company to throw in the towel.
“If the molecule works the way we think it does based on animal studies, we’re in good shape. If it isn’t, then maybe we shouldn’t be doing it,” Hughes says.
