Two-year-old Trubion Pharmaceuticals Inc. raised $32 million in a Series B financing to advance at least two of its small modular immunopharmaceuticals (SMIPs) into Phase I testing.

Lead product TRU-015 should move into the clinic in early 2005 as a treatment for autoimmune and inflammatory diseases. Trubion's second product, TRU-016, would enter a Phase I trial for certain oncology indications after TRU-015.

"The proceeds from this round will be used to advance some of our lead product candidates into and through the initial phases of clinical development," said Peter Thompson, co-founder, president and CEO of Seattle-based Trubion, "as well as for the continued expansion of what already is a very deep pipeline."

While Thompson would not disclose any specifics about Trubion's earlier SMIP products, he said the company has "a bit of an embarrassment of riches." All of the potential products belong to the small modular immunopharmaceuticals class of molecules. SMIPs use key structures, or modules, in naturally occurring proteins that the company optimizes to work together in a single molecule.

"Small modular immunopharmaceuticals, as the name suggests, are significantly smaller than antibodies, which enables them to enjoy significant advantages in terms of biodistribution, to get to targets of interest for drug action," Thompson said.

With improved biodistribution, they can be designed for optimal potency in different diseases, separating them from existing immunopharmaceuticals. SMIPs roughly are one-third to one-half the size of antibodies.

In preclinical testing, TRU-015 showed rapid and complete depletion of circulating B cells for more than 28 days following the second injection. TRU-016 also showed that it binds to and effectively kills malignant B cells through apoptosis, complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity.

Thompson could not say how long the Series B financing would last Trubion, but he indicated the company would look to form alliances for later-stage clinical work. The SMIP technology, he said, is producing more potential products than any organization could possibly move forward on its own.

"The number of assumptions that have to be made in trying to figure out when or if we might go back to the public or private equity markets for more capital is daunting," he told BioWorld Today.

Palo Alto, Calif.-based Prospect Venture Partners and Menlo Park, Calif.-based Venrock Associates co-led the financing. David Schnell, a managing director of Prospect, and Anders Hove, a general partner of Venrock, joined Trubion's board. Existing investors that participated included Chicago-based Arch Venture Partners, Seattle-based Frazier Healthcare Ventures, Boston-based Oxford Bioscience Partners and New York-based ATP Capital.

"We were in the fortunate position of being able to attract substantial interest from a variety of private equity investors, so we were in a position to pick and choose the parties that would be involved in the Series B financing," Thompson said. "I'm very pleased with our selection to work with Venrock and Prospect."

The SMIP technology came out of inventions by company co-founders, which include Thompson, as well as Jeff Ledbetter and Martha Hayden Ledbetter, two scientists who worked at the Pacific Northwest Research Institute in Seattle prior to pulling together the first institutional financing for Trubion. Ken Mohler and Edward Clark also co-founded Trubion in 2002. Jeff Ledbetter serves as the company's chief scientific officer, while Mohler is senior vice president of research and development. Clark is a professor at the University of Washington who serves on the company's scientific advisory board.

With a name meaning "true biology," Trubion aims to be one step ahead of evolution, Thompson said. The company has raised $45.6 million since inception. It completed its Series A round at the end of 2002, raising $13.6 million. The company employs 30 people.