Eisai Pays up to $2B for ADC Bearing Its Halaven as Payload

Published: May 09, 2023 By Heather McKenzie

Pictured: Two scientists in a medical research laboratory/gorodenkoff/iStock

In the latest deal in a resurgent space, Eisai announced Monday it would pay Bliss Biopharmaceutical up to $2 billion in a clinical trial collaboration for an antibody-drug conjugate carrying its chemotherapy drug Halaven (eribulin).

Specifically, Eisai will hand over an undisclosed amount to see BB-1701, a human epidermal growth factor receptor 2 (HER2)–targeting ADC, through an option period. If Eisai exercises the option, the pair will then enter into a strategic collaboration license agreement that could see the Hangzhou, China–based company reel in a cumulative $2 billion from development and commercial milestones, as well as sales royalties. BlissBio would also receive an option to exercise payment.

For Eisai's part, the deal comes with the potential to develop and commercialize BB-1701 globally, excluding Greater China. In 2018, Eisai granted BlissBio global exclusive development rights for several ADCs that could use Halaven as the payload.

ADCs are designed to combine the benefits of targeted therapy with the cytotoxicity of chemotherapy. The technology comprises a cytotoxic payload conjugated via a chemical linker to a monoclonal antibody that targets an antigen expressed on a cancer cell's surface.

The decision to co-develop BB-1701 was based on the status of Phase I/II trials being conducted by BlissBio, according to a statement issued Monday by Eisai. Under the agreement, Eisai will conduct a Phase II clinical trial in breast cancer. BB-1701 also has potential in lung and other solid tumors that express HER2, Eisai noted in the press release.

Eisai could have its sights set on the market share currently occupied by Daiichi Sankyo and AstraZeneca's Enhertu (fam-trastuzumab deruxtecan-nxki), an ADC approved by the FDA in December 2019 to treat HER2-positive metastatic breast cancer.

For BlissBio, which launched in 2017, the deal with Eisai "is a significant accomplishment . . . as it allows us to further develop this promising compound, BB-1701," Ziping Wei, CEO of BlissBio, said in the release, pointing to Eisai's "strong oncology R&D capability worldwide."

2023's ADC Rush

The deal is just the latest in a string of multi-million- and billion-dollar acquisitions and collaborations centered on ADCs. In February, AstraZeneca augmented its portfolio by paying KYM Biosciences $63 million upfront for the global rights to CMG901, a Claudin 18.2–targeting ADC. In April, BioNTech signed a $170 million licensing deal with China-based Duality Biologics for exclusive access to two ADCs for solid tumors, and Bristol Myers Squibb teamed up with German biotech Tubulis in a development deal also focused on solid tumors.

But the cornerstone of this M&A cascade is arguably Pfizer's March announcement that it will acquire ADC pioneer Seagen for $43 billion. Pfizer beat out Merck for the rights to Seagen's portfolio after talks between Merck and Seagen broke down in mid-2022 over price. Pfizer will add three ADCs to its commercial portfolio for a total of five, a company representative previously told BioSpace in an e-mail.

Heather McKenzie is a senior editor at BioSpace, focusing on neuroscience, oncology and gene therapy. You can reach her at [email protected]. Follow her on LinkedIn and Twitter: @chicat08

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