Mersana Therapeutics, Inc., a biopharmaceutical company developing its Fleximer® antibody-drug conjugate (ADC) platform and therapeutics, today announced that it was awarded U.S. Patent No. 8,685,383, entitled “Protein-Polymer-Drug Conjugates.” This patent provides Mersana broad coverage for its polymer-based Fleximer-ADC platform technology. The patent covers Fleximer-drug conjugates that can be linked to an antibody to create next-generation antibody drug conjugates.

“This patent issuance provides Mersana flexibility to partner with any antibody company to generate novel Fleximer-ADC therapeutics,” said Eva M. Jack, Chief Business Officer of Mersana Therapeutics. “In particular, using Fleximer our partners can increase the number of small molecule drug payloads per antibody with significantly improved properties in comparison to traditional ADC technologies, with any antibody they provide.”

About Fleximer® Antibody-Drug Conjugate Technology
 Mersana’s next-generation Fleximer® antibody-drug conjugate (ADC) technology is based on the Company’s proprietary biodegradable polymer system, known as Fleximer®, and a wide variety of linkers that allow for the attachment of an extensive range of anti-tumor payloads to Fleximer. As an example, once loaded with the drug(s), Fleximer is then attached, through a stable linker that is different from the drug linker(s), to an antibody or antibody alternative to create a Fleximer-ADC. Mersana’s novel linker systems are designed to be stable in the blood stream and release the potent payloads once inside the targeted cancer cell. Mersana’s Fleximer-ADC technology provides several key advantages over currently available approaches, including: ability to deliver diverse payloads; opportunity to significantly increase drug loading per antibody; potential use with antibody fragments and alternative targeting moieties, in addition to monoclonal antibodies; and optimization of the drug conjugate size to efficiently perfuse solid tumors, while retaining a long half-life associated with antibody-based ADCs.

About Mersana Therapeutics, Inc.
 Mersana engineers novel drug conjugates that maximize the potential of new and established therapeutic classes. Mersana is developing, with select pharmaceutical partners, a portfolio of next-generation Fleximer-ADCs with superior properties not found with current ADC technologies. The company is also advancing its own pipeline of Fleximer-ADCs with best-in-class potential to address unmet needs and improve patient outcomes in multiple oncology indications.

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