UPDATED: With Roche in the rearview mirror, Constellation Pharma grabs $55M round

About four months after Roche completed its slow-motion decoupling with Constellation Pharmaceuticals, the biotech has moved ahead with a $55 million venture round. 

The latest "mezzanine" round was led by Topspin Partners and a group of unnamed investors who opted to gamble on the company, which was also backed by a group of founders that includes Third Rock Ventures, The Column Group, Venrock and SR One.

Constellation CEO Keith Dionne

Back in August, CEO Keith Dionne made no secret of the fact that the company was interested in joining the IPO queue. Since then, though, the biotech IPO window has narrowed considerably as share prices throughout the industry swooned following a three-year power surge on the market.

At this point, Dionne tells me today, an IPO is one of the options for the company to consider. He's looking more closely at some potential new partnerships to see "who can step in with us, with their capabilities, to help take advantage of these pretty darn exciting directions." And the right kind of partnership, he added, could be "IPO enabling."

Roche ($RHHBY) paid $95 million to partner with Constellation on epigenetics--the science of turning the right genes off and on--and set up a deal that gave the pharma giant a chance to bag the company for a mutually agreed on price. But the collaboration ended on a bitter note.

Roche says it figured that Constellation wasn't the right "strategic fit," especially in light of the rest of the work it's doing in the field. Dionne, for his part, said that Roche was only interested in cherry-picking a few assets for its West Coast operations and then shutting down the company in Cambridge, MA. Dionne was forced to cut 23 staffers at the beginning of the year as the collaborative part of the deal wound down, months ahead of the move to drop the option.

Now the company is growing again, says Dionne, rising to 55 staffers in recent months with plans to add more in the months ahead.

Whatever happens on the IPO front, the immediate goal at Constellation is to stay focused on a pair of clinical-stage programs: a bromodomain and extraterminal inhibitor as well as an EZH2 inhibitor for cancer. And they have the money to make some real progress.

- here's the release

Special Report: FierceBiotech's 2008 Fierce 15 - Constellation Pharma