Infinity Pharmaceuticals Inc. raised $70 million in Series B funding, money it will direct toward research and development and to building its Infiniplex platform.

Infinity President and CEO Steven Holtzman said the financing market is "paradoxical" at the moment, meaning while there is a significant amount of money in funds, the investors are still "very wary and price sensitive."

Holtzman said that "this financing happening is a reminder" that important new medicines are going to come out of biotechnology.

"We shouldn't get too depressed by a transient down market," said Holtzman, formerly chief business officer at Millennium Pharmaceuticals Inc.

Boston-based Infinity was founded in February 2001 and now has 70 employees, having raised $83 million to date. The latest funding, along with revenue from potential partnerships, should combine to make the company sustainable, Holtzman said. The company is seeking out pharmaceutical and biotech companies, as well as academic entities, with which to partner.

The Infiniplex approach to chemistry is designed to generate diverse new small molecules to address a range of biologic targets that current chemistries cannot, Holtzman said.

"The last decade has really been about biology, a revolution in biology," Holtzman said, explaining that now that the human genome is in hand, there are "many, many" targets, but there hasn't been a similar revolution in chemistry to match the one in biology.

The Infiniplex library consists of large numbers of molecules that feature complexity of 3-dimensional structure, stereochemistry and rigidity, the company said, noting that those features are characteristic of drugs that are both highly active and selective. Previously, the company said, those features typically came from natural sources, which come with disadvantages in terms of suitability for drug discovery efforts.

From a biology perspective, Infinity uses the Infiniplex libraries by taking multiple approaches to screen the molecules created through the chemistry platform, including target-based screens, target-class screens and phenotypic and pathway screens, the company said.

"The knowledge systems that are being deployed are not about bioinformatics, but are about being able to unleash the creative potential of the scientists and business people in the company by providing them the information necessary to make better decisions," Holtzman said.

Three Crowns Capital, of Bermuda, served as placement agent for the financing, which was led by Advent Venture Partners, of London. Series A investors who participated in this round were Venrock Associates, of New York, and Prospect Venture Partners, of Palo Alto, Calif.

New investors included Vulcan Ventures Inc., of Seattle; HBM Bioventure Ltd., of Switzerland; Novartis Bioventure Fund, of La Jolla, Calif.; Wellcome Trust Ltd., of London; Tallwood LP, of Palo Alto, Calif.; Lotus BioScience Investment Holding, of Hong Kong; and Alexandria Equities LLC, of Pasadena, Calif.

The round also included private investors Stelios Papadopoulos, managing director of SG Cowen Securities Corp., of New York, and two founders of the company: Holtzman and Bowstreet Chairman Frank Moss.