Mersana grabs $27M from Pfizer, NEA and others for muscled cancer drugs

Fresh from revealing a $2.6 billion fund last week, New Enterprise Associates (NEA) has jumped aboard as a lead backer of Mersana Therapeutics' next-gen antibody drug conjugates--one of the hottest areas of cancer treatment. Mersana plans to use the $27 million Series A-1 round of financing--which was led by NEA and includes funds from Pfizer Venture Investments, Fidelity Biosciences, ProQuest Investments, Rho Ventures as well as Harris and Harris Group--to build out its own pipeline of antibody-drug conjugates (ADCs) for fighting cancer and advance its enabling technology for the treatments.

David Mott, a general partner at NEA and former CEO of the large biotech MedImmune, has become chairman of Mersana. Mott, who also led NEA's investment in the newly public cancer drug specialist Tesaro ($TSRO), stated in a press release that Mersana presents an opportunity to advance the ADC field, which has benefitted from the successes of such treatments from Seattle Genetics ($SGEN), ImmunoGen ($IMGN) and Genentech. And Mersana has become the very first biotech to tap NEA's relatively massive $2.6 billion fund.   

"It's a great distinction … and having (NEA) come in with Pfizer is exactly what this company needs at this point to build itself," Mersana CEO Nicholas Bacopoulos told FierceBiotech in an interview. "We will need the financial and intellectual resources of NEA to succeed, and we feel that this is a validation and a turning point."

Mersana, founded in 2001, has found success with its recent focus on ADCs, which involve various compounds that include targeted antibodies that carry potent anti-cancer toxins to tumor cells. The biotech and Endo Pharmaceuticals ($ENDP) inked a $270 million pact in March, giving Mersana its first pharma collaboration for developing an ADC for combating cancer. Bacopoulos says that his company will pursue more collaboration deals with pharma groups as part of its strategy to raise funds and advance its ADC technology.

The company builds ADCs with a biodegradable polymer molecule, to which an antibody and a payload of small-molecule drugs are linked. This so-called Fleximer platform offers solubility advantages over current approaches to making ADCS, among other benefits, Bacopoulos explained. While the company's ADC technology has shown great promise in preclinical studies, Mersana hasn't yet embarked on a human study for one of these compounds. The last round of financing, which brings the total amount raised at the company to $77 million, is expected to carry the operation through Investigational New Drug (IND) application approvals for the drugs.

In other financing news, the Bay Area's Cytomx Therapeutics, a developer of targeted antibody drugs, revealed an expansion of its Series B round to $41 million, with Canaan Partners leading the deal. The second-round financing, which was initially said to total $30 million in September 2010, has also attracted backing from Third Rock Ventures and Roche Venture Fund.

- here's the Mersana release
- and Cytomx's statement