CAMBRIDGE, Mass.—Mersana Therapeutics Inc. announced that the company has expanded its ongoing collaboration with Takeda Pharmaceutical Co. Ltd. to create novel Fleximer antibody-drug conjugate (ADC) candidates to include additional oncology-relevant targets. Mersana is eligible to receive additional upfront and milestone payments potentially totaling over $300 million under the expanded collaboration, subject to future success of the programs. The partners’ collaboration was announced in April 2014, and since then Mersana and Takeda have been conducting preclinical proof-of-concept studies for several Fleximer-ADCs against an undisclosed oncology target under a research license covering Mersana’s Fleximer-ADC technology. Takeda has already exercised an option to license commercial rights for the first drug candidate developed under this collaboration.
“The expansion of our collaboration with Mersana is a testament to the importance of partnership in innovating new treatments for cancer,” said Dr. Christopher Claiborne, head of the Oncology Drug Discovery Unit at Takeda. “Now encompassing multiple therapeutic targets and potential drug candidates, we look forward to further advancing the next generation of ADCs under our expanded collaboration with Mersana with the goal of bringing new therapies to patients around the world.”
“We are delighted to expand our relationship with Takeda and are excited about the prospects of Fleximer-ADC candidates that have progressed well into preclinical development,” said Eva M. Jack, chief business officer of Mersana Therapeutics. “Our highly productive strategic partnership with Takeda affords us the ability to advance potential new medicines with superior properties closer to the clinic, as well as enhance our Fleximer platform.”
On Oct. 27, Takeda signed an agreement with Mersana through its wholly owned oncology subsidiary, Millennium Pharmaceuticals Inc. The October extension built on the original April 2014 agreement, under which Takeda provided an upfront payment to Mersana for the right to utilize Fleximer technology to develop novel ADC candidates for indications in oncology.
“Takeda exercised an option in October to license commercial rights for the first ADC developed in the collaboration,” Dr. Timothy B. Lowinger, chief scientific officer of Mersana, tells DDNews. “Mersana offers a unique conjugation platform for partners interested in pursuing next-generation ADCs. We have a highly differentiated approach, which has drawn the attention of several major pharmaceutical partners. In particular, we have demonstrated the benefit of our approach to address lower-expression targets, potentially expanding the number of targets and increasing the patient populations that can potentially be addressed with an ADC approach,” he states.
“We cannot disclose progress in our research and preclinical activities with our partners,” notes Lowinger, nor will the company disclose additional details about the new targets. “Mersana is independently developing our own proprietary ADCs and in the past year has progressed these through exploratory non-human primate tolerability studies and to the GMP manufacturing stage,” Lowinger adds.
Mersana is currently conducting research and creating ADCs that are conjugates of Takeda’s antibodies and Mersana’s diverse payload platforms, which combine a cytotoxic payload with the Fleximer polymer and custom linkers. In addition to providing antibodies, Takeda is responsible for product development, manufacturing and commercialization of any Fleximer-ADC products. Mersana remains eligible to receive milestone payments and royalties on worldwide net sales of any resulting ADC products.
“Our productivity and Takeda’s license for the Fleximer-ADC’s commercial rights speak to the Fleximer polymer and proprietary conjugation technology providing an optimal platform for the development of next-generation ADCs,” according to Lowinger. “Not only is Mersana delivering unique, highly differentiated Fleximer-ADCs to our industry-leading partners, but we are actively developing an internal pipeline with superior antibodies conjugated to our payload platforms, as well.”
“The collaboration with Mersana has progressed rapidly and has proven beneficial for our discovery research efforts,” said Claiborne. “We have been impressed with the results generated through use of the Fleximer platform, and we are looking forward to the continued success of this collaboration.”
Under the April 2014 agreement, Takeda provided an upfront payment to Mersana for the right to utilize Fleximer technology to develop novel ADC candidates for indications in oncology. Mersana is currently conducting research and creating ADCs that are conjugates of Takeda’s antibodies and Mersana’s diverse payload platforms, which combine a cytotoxic payload with the Fleximer polymer and custom linkers. In addition to providing antibodies, Takeda is responsible for product development, manufacturing and commercialization of any Fleximer-ADC products. Besides the upfront payment, Mersana also stands to receive milestone payments and royalties on worldwide net sales of any resulting ADC products.
Mersana’s next-generation Fleximer 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 drug(s), Fleximer is then attached through a stable linker that is different from the drug linker(s) to the antibody or antibody alternative to create a Fleximer-ADC. Mersana’s novel linker systems are designed to be stable in the bloodstream and to release the drug payloads once inside the targeted cell. Mersana’s Fleximer-ADC technology provides several key advantages over currently available approaches, including the ability to deliver diverse payloads, the opportunity to significantly increase drug loading per antibody, significantly improved physicochemical properties and facile manufacturing. Mersana’s proprietary polymer payload platforms include Dolaflexin, an auristatin-polymer conjugate; Vindeflexin, a vindesine-polymer conjugate; and Cytoflexin, a tubulysin-polymer conjugate.