Mersana, Endo to collaborate on ADC development

CAMBRIDGE, Mass.—Mersana Therapeutics, Inc. and EndoPharmaceuticals have established a collaboration agreement for the developmentof next-generation antibody-drug conjugates (ADCs). Per the terms of theagreement, Endo will pay an upfront fee of an undisclosed amount to Mersana forthe right to utilize Mersana's Fleximer technology to develop novel ADCcandidates against a particular cancer target.

"The collaboration with Mersana further enhances Endo'sDiscovery and Early Development portfolio and is validation of ourcollaborative R&D approach for drug discovery and development," IvanGergel, Executive Vice President of R&D and Chief Scientific Officer atEndo, said in a press release. "Using Mersana's Fleximer-ADC technology, we aimto develop more efficacious and safer treatment options to improve patientoutcomes."

Mersana will be responsible for research related to and thecreation of ADCs that are conjugates of its highly potent cytotoxic payloads,its Fleximer polymer and custom linkers and Endo's novel antibodies. Inaddition to the aforementioned funding, Endo is responsible for providing novelantibodies as well as product development, manufacturing and commercializationof any Fleximer-ADC products. As part of the agreement, the two companies mayagree to pursue two additional targets over the course of the next two years.If all three targets end up being pursued, Mersana will stand to receive morethan $270 million in progress-dependent milestones as well as royalties onworldwide net sales of any ADC products that result from the agreement.

Mersana's next-generation ADC technology is based onFleximer, its proprietary biodegradable polymer system, as well as a widevariety of novel linkers that allow for a broad range of anti-tumor payloads tobe attached to Fleximer. Once Fleximer is loaded with the drug, it is attachedto an antibody or antibody fragment through a highly stable linker in order tocreate an ADC. The novel linker systems are engineered to be stable in theblood stream as well as to release their payloads once they get inside of theirtargeted cancer cell. The technology offers the ability to deliver alternativepayloads beyond anti-tubulins, as well as the opportunity to drasticallyincrease drug loading per antibody. The potential to use it with antibodyfragments in addition to monoclonal antibodies is another benefit.

"Our proprietary conjugation technologies, centered onFleximer, are particularly well-suited to expand the therapeutic potential ofADCs by enabling greater cytotoxic payload, diverse mechanisms of action,better tumor penetration, and improved stability achieved with optimizedlinkers," Nick Bacopoulos, Chief Executive Officer of Mersana, said in a pressrelease. "We look forward to working with Endo to incorporate their antibodiesagainst a very promising oncology target into next-generation Fleximer-ADCcandidates. We expect this to be just the first of several importantFleximer-ADC collaborations for Mersana."

SOURCE: Mersana Therapeutics press release