Acceleron Prices Upsized IPO at $15 Per Share, Begins Trading Thursday

Xconomy Boston — 

Acceleron Pharma has found a sweet reception on Wall Street, continuing 2013’s run of biotech IPO successes.

The Cambridge, MA-based biotech priced its IPO late Wednesday, selling 5.58 million shares at $15 apiece. The figure comes in at the high end of Acceleron’s projected $13 to $15 per share range, and reflects big demand from investors—Acceleron initially sought to sell 4.65 million shares through the offering.

In addition, Summit, NJ-based Celgene (NASDAQ: CELG), both an investor and a partner of Acceleron, has agreed to buy 667,000 shares of stock at the IPO price. Celgene cut a similar type of deal with Agios Pharmaceuticals (NASDAQ: AGIO) when it priced its IPO in July.

With the Celgene deal and the IPO raise combined, Acceleron has hauled in close to $94 million before discounts due to underwriters. That number will jump even higher should Acceleron’s underwriters exercise their 30-day options to buy an additional 837,000 at the IPO price—a good bet given the reception Acceleron’s gotten from investors so far.

Acceleron has a first-day market capitalization of more than $400 million. It will begin trading on the Nasdaq under the ticker symbol “XLRN” this morning.

Acceleron’s largest stockholders prior to the IPO were Polaris Venture Partners (15.6 percent), Advanced Technology Ventures (12.5 percent), Venrock (12.4 percent), Celgene (12.3 percent), Flagship Ventures (11.1 percent), and OrbiMed Advisors (10.6 percent). It had raised $144 million in equity financing from venture investors and partners since its inception in 2003.

Citigroup Global Markets, Leerink Swann, JMP Securities, and Piper Jaffray are its underwriters.

Acceleron’s CEO and co-founder John Knopf, and several of the company’s other executives, are veterans of the Cambridge-based Genetics Institute, a biotech powerhouse in the ‘80s and ‘90s. The company is discovering drugs that block one of the roughly 30 members of the TGF-beta superfamily of proteins, which are involved in red blood cell formation. That approach has led to two experimental drug candidates, known as sotatarcept and ACE-536, that are designed to stop anemia in patients with beta-thalassemia or myelodysplastic syndrome, two red blood cell disorders. Acceleron is also conducting two mid-stage clinical trials testing the drug as a treatment for multiple myeloma and chronic kidney disease.

Celgene is funding those trials as part of a big early-stage partnership it forged with Acceleron in 2011, through which it agreed to bankroll all of the development and commercial expense costs of sotatarcept and ACE-536. Celgene is splitting the economics of the two drug candidates with Acceleron in the U.S., and getting all the rights to any revenue they bring in internationally, should they make it through clinical trials and win approval from regulators.

Acceleron stands to receive as much as $567 million in milestone payments tied to various development goals, and royalties in the “low-to-mid 20 percent range” on sotatarcept and ACE-536, according to SEC filings.

Acceleron also has a third cancer drug candidate in development called dalantercept, though it doesn’t have a partnership in place for that program.

Acceleron found slightly more success pricing an offering this week than South San Francisco, CA-based Five Prime Therapeutics (NASDAQ: FPRX). The company, which is developing drugs for cancer and autoimmune diseases, raised $62 million by selling 4.8 million shares at $13 apiece—the midpoint of its projected $12 to $14 per share range.