[[Corrected 4/22/11 at 2:15 pm]]Mersana Therapeutics, a Cambridge, MA-based drug maker, has brought in $6 million of a targeted $10 million debt offering, from seven investors, according to an SEC filing. Last year, the company inked a deal that could be worth $334 million with Israel-based Teva Pharmaceutical Industries, for developing a new polymer-based drug for cancer and other diseases. [[Editors Note: An earlier version of this news brief incorrectly described Mersana as a maker of generic drugs and incorrectly listed Teva as based in Japan. We regret the errors.]] Earlier this week Mersana announced that it hired Forest Laboratories veteran Michael Metzger as its chief operating officer and executive vice president.