Asia PR News

CAMBRIDGE, Mass., May 30 /PRNewswire-AsiaNet/ –

First compound based on company’s proprietary Fleximer(R)
polymer platform enters clinical trials

Mersana Therapeutics, a cancer therapeutics company, announced today that
it has initiated a Phase I open-label, dose-escalation trial of its lead
product candidate, XMT-1001, in patients with solid tumors. XMT-1001 is a
polymer-based prodrug of camptothecin (CPT), a well-characterized topoisomerase
I inhibitor with potent anti-tumor activity.

The primary objectives of the study are to determine the safety,
tolerability and pharmacokinetic profile of XMT-1001. Patients also will be
assessed for evidence of anti-tumor activity. The study is being conducted at
three clinical sites: University of Maryland, Greenbaum Cancer Center under the
supervision of Dr. Edward Sausville; TGen Clinical Research Services at
Scottsdale Heathcare’s Virginia G. Piper Center under the supervision of
Stephen P. Anthony, D.O. and Daniel Von Hoff, M.D.; and U.S. Oncology in
Albany, NY under the supervision of Lawrence Garbo, M.D.

"Taking our first compound into the clinic in less than eighteen months
from financing for IND-enabling studies is a major milestone for Mersana," said
Julie Olson, Ph.D., President and CEO of Mersana. "In addition to XMT-1001, we
have several other active programs in our pipeline that take advantage of the
unique features of our Fleximer(R) platform and we look forward to advancing
these compounds into the clinic," she concluded.

Preclinical data from studies with XMT-1001 presented at the recent
American Association of Cancer Research annual meeting showed that the agent
was a potent and efficacious agent against tumor xenografts of human colon
cancer and human ovarian cancer. Fleximer helps deliver up to 75 times more
active CPT (camptothecin) to cancer tumors than with free CPT administration.

"Derivatives of the anticancer agent camptothecin, such as Camptosar(R),
have been successful but their true clinical potential has been limited by
safety issues," commented Robert J. Fram, M.D., Chief Medical Officer at
Mersana. "It is our hope that our Fleximer-based CPT conjugate, XMT-1001, will
significantly improve the safety and therapeutic window of CPT and position the
compound to be effective in a broad range of solid tumors."

About XMT-1001
XMT-1001 is Mersana’s most advanced Fleximer-based product candidate. It
utilizes a novel, dual release mechanism to liberate a camptothecin prodrug,
which is then converted within cells into camptothecin, a DNA topoisomerase I
inhibitor. In pre-clinical studies, XMT-1001 was better tolerated and more
efficacious than either camptothecin or irinotecan in models of human cancer,
showing extended plasma half-life and high concentrations in tumor tissue.

About Fleximer Technology
Fleximer technology improves the therapeutic index of cytotoxic compounds
useful as anti-cancer agents by uniquely combining biodegradability with
"biological stealth" properties, making Fleximer materials and their conjugates
long-circulating and non-immunotoxic. Fleximer molecules are characterized by
solubility in water, stability in common manufacturing procedures and in normal
physiological conditions, and non-enzymatic biodegradability upon uptake by
cells.

About Mersana Therapeutics, Inc.
Mersana, a privately held, venture-backed company, is developing novel
oncology agents based on clinically validated compounds through the use of
Fleximer(R), a proprietary bio-degradable and bio-inert material that enhances
the pharmacokinetics, safety, and solubility of drugs. Mersana has an exclusive
license from the Massachusetts General Hospital for its core technologies.
Mersana’s pipeline includes compounds with activity against multiple tumor
types and human proof-of-concept that are improved by its proprietary
technologies. Mersana’s investors include Fidelity Biosciences, ProQuest
Investments, Rho Ventures, Harris & Harris Group and PureTech Ventures.

Camptosar(R) is a registered trademark of Pfizer.

SOURCE: Mersana Therapeutics, Inc.

CONTACT: Pete Leone,
Chief Operating Officer of Mersana Therapeutics, Inc.,
+1-617-498-0020; or

Media:

Kathryn Morris of KMorrisPR,
+1-845-635-9828,
kathryn@kmorrispr.com,
for Mersana Therapeutics, Inc.