Zafgen completes $96 million IPO with big demand for shares


Zafgen Inc. has completed its initial public offering amid strong demand from investors. The Cambridge biotech firm increased the size of the offering and sold shares at the top of its projected range on Wednesday, raising a total of $96 million. The IPO is the 10th by a Massachusetts-based biotech firm so far this year, topping the tally from last year of nine and setting a new record.

The size of the offering could rise to $110.4 million if underwriters purchase over-allotment shares.

Most recently, Zafgen had said it planned to sell 5 million shares for between $14 and $16 a piece. The IPO ultimately included 6 million shares.

Zafgen said it intends to use some of the proceeds from the stock sale to finance a Phase 3 clinical program for its lead product candidate, set to begin this year.

Zafgen is developing drugs to treat severely obese patients who aren’t helped by other treatments. The firm’s lead product candidate is a twice-a-week injection.

The drug works by re-balancing the way the body produces and uses fat stored in adipose tissue, the company says. The imbalances in obese people make it more difficult for them to lose weight and keep it off, according to Zafgen.

In January the firm reported that a Phase 2a study of its lead drug, in patients with a severe form of genetic obesity, Prader-Willi syndrome, reduced body fat content by 8.1 percent after four weeks of treatment.

According to the Obesity Action Coalition, severely obese persons can face a half dozen or more related medical conditions, and 112,000 deaths a year in the US are attributed to obesity.

Zafgen said the cost of treating patients suffering from Prader-Willi syndrome can typically run $100,000 to $200,000 a year.

The firm had raised $104 million in equity funding since its launch in 2005. Top shareholders include founding investor Atlas Venture of Cambridge, which owns a 35.6 percent stake in Zafgen, and Third Rock Ventures of Boston, which owns 35.4 percent of the company’s shares.

Kyle Alspach has worked in journalism in Massachusetts since 2005 and was one of the original staff writers at BetaBoston.
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