Mersana Therapeutics Expands Senior Leadership Team with Appointments of Peter Park, Ph.D., as VP of Biology and Wayne Foster, CPA, as VP of Finance

CAMBRIDGE, Mass. -- January 23, 2013 -- Mersana Therapeutics, Inc., a biopharmaceutical company developing its Fleximer® antibody-drug conjugate (ADC) platform and pipeline of small molecule Fleximer conjugates, announced today that the company has expanded its senior leadership team. Peter U. Park, Ph.D., has joined the company as Vice President of Biology, and Wayne Foster, CPA, has joined as Vice President of Finance.

"The addition of Peter to our senior team reflects Mersana's focus on our next generation Fleximer antibody-drug conjugate (ADC) platform," said Nicholas Bacopoulos, Ph.D., President and Chief Executive Officer of Mersana. "Peter's extensive and successful experience with ADC discovery and development will be integral to the continued advancement of our Fleximer-based ADC platform and pipeline in oncology. Additionally, as we continue to advance our existing collaborative projects and grow through new strategic alliances, Peter's experience with Pharma and Biotech collaborations will be fundamental. Wayne's broad and deep expertise on strategic planning, alliance management, financial processes and controls, and fundraising will also serve Mersana very well as we progress to our next stage of growth."

Dr. Park brings to Mersana significant experience in the discovery and development of antibody-drug conjugate therapies. Prior to joining Mersana, he was a co-founder and Chief Executive Officer of Habgen, Inc., a start-up focused on antibody therapeutics. Prior to that, Dr. Park served at ImmunoGen, Inc. for 10 years, most recently as Senior Director of Discovery Research. In this role, he managed the discovery research portfolio for the development of novel monoclonal antibody and antibody-drug conjugates for oncology, advancing two compounds into Phase 1 and several additional projects into late discovery and preclinical development. Additionally, he oversaw ImmunoGen's research collaboration with Sanofi. He is the author on many patents and has contributed to numerous scientific publications. Dr. Park earned his Ph.D. and B.S. in Biology from the Massachusetts Institute of Technology.

Mr. Foster has held management positions in several life science and technology companies. Prior to joining Mersana, he served for nine years as Senior Director of Finance at Tolerx, Inc. In this role, he was responsible a wide variety of finance functions as the company grew from early stage through precommercialization. Mr. Foster also served as Senior Manager at Arthur Andersen LLP where he specialized in emerging life science and technology companies. He earned his B.B.A. in Accounting from the University of Massachusetts Amherst.

About Mersana

Mersana engineers novel drug conjugates that maximize the potential of new and established therapeutic classes. Utilizing its proprietary conjugation technology, which is comprised of the Fleximer® polymer and a broad array of customizable linker chemistries, Mersana is developing its next-generation antibody-drug conjugate (ADC) platform with superior properties not found with other ADC technologies.  Mersana is currently working with a number of top Pharma companies to develop next generation Fleximer-ADCs and most recently announced a $270 million collaboration with Endo Pharmaceuticals in March, 2012. The company is also advancing its own pipeline of next-generation drugs with best-in-class potential to address unmet needs and improve patient outcomes in multiple oncology indications. Mersana's investors include New Enterprise Associates (NEA), Pfizer Venture Investments, Proquest Investments, Fidelity Biosciences, Rho Ventures and Harris and Harris Group. Mersana was founded by PureTech Ventures, LLC and a group of leading academics and clinicians.

For more information, visit www.mersana.com.

Fleximer® is a trademark of Mersana Therapeutics, Inc.