Mersana Therapeutics expands partnership with Takeda

Anna Protopapas, CEO of Mersana Therapeutics
Anna Protopapas, CEO of Mersana Therapeutics(Kayana Szymczak/The Boston Globe

Mersana Therapeutics Inc. of Cambridge said Wednesday it expanded a partnership with Takeda Pharmaceutical Co., giving the Japanese company the rights to market Mersana’s lead cancer-fighting drug candidate outside the United States and Canada.

The expanded alliance also allows Takeda, which operates a cancer drug research lab in Cambridge, to use Mersana’s drug delivery technology, called Fleximer, in research on additional compounds. Mersana eventually could receive milestone payments of more than $750 million as well as royalties if drugs resulting from that research are approved.

The partnership agreement allows Mersana “to retain significant value and to continue to build our pipeline,” Mersana chief executive Anna Protopapas said in an interview.


“We have the potential to make a real difference in people’s lives,” Protopapas said.

Takeda and Mersana struck earlier collaboration deals in 2014 and 2015 that let Takeda use Fleximer — a technology that uses cancer-killing antibody drug conjugates, which discriminate between healthy cells and tumors — for experimenting with certain compounds and disease targets. The technology can deliver drugs at higher doses directly to tumors.

Under the latest deal, Mersana, backed by an investor group that includes venture firms New Enterprise Associates, Fidelity Biosciences, and Pfizer Venture Investments, will receive a $40 million upfront payment from Takeda and an additional $20 million if US regulators allow Mersana’s lead drug candidate to enter clinical trials.

That drug, called XMT-1522, targets breast, gastric, and non-small cell lung cancers.

Takeda, which acquired Cambridge-based Millennium Pharmaceuticals Inc. in 2008, also agreed to invest up to $20 million in a future funding round for Mersana.

Protopapas, an executive well known in Boston area biopharma circles, joined Mersana as chief executive in March. She had previously worked at Takeda and its predecessor, Millennium, for more than a decade, stepping down in September 2014 as president of Takeda’s oncology business.


While she ran the Takeda oncology unit when it struck its initial partnership with Mersana, she had not been directly involved in the collaboration.

Mersana’s technology, which was developed in-house, is a more powerful version of first-generation antibody drug conjugates pioneered by companies such as ImmunoGen Inc. of Waltham and Seattle Genetics Inc., said Protopapas.

She said it has the potential to be used in the development of multiple cancer drugs marketed by Mersana and partners.

“The ability to carry higher doses allows us to go after targets that the first generation of this technology can’t go after,” Protopapas said.

Preclinical data reported by Mersana indicated that XMT-1522, its lead experimental drug, may be an active agent in fighting tumors in patients with the HER2 gene, which plays a role in the development and progression of aggressive cancers.

Mersana plans to seek Food and Drug Administration approval later this year to begin clinical trials of XMT-1522.

Robert Weisman can be reached at robert.weisman@globe.com. Follow him on Twitter @GlobeRobW.