Eisai to independently develop and commercialize Fzec ADC

Eisai Co., Ltd., a Tokyo-based pharmaceutical company led by CEO Haruo Naito, announced the termination of its strategic global collaboration with Bristol Myers Squibb (BMS) concerning the co-development and co-commercialization of farletuzumab ecteribulin (FZEC). This decision stems from BMS's ongoing efforts to prioritize its portfolio. As a result, Eisai will now fully own the rights to FZEC, taking charge of its global development and commercialization independently. The company aims to expedite the development process to bring this drug to patients as swiftly as possible.

FZEC, previously known as MORAb-202, is Eisai’s inaugural antibody drug conjugate (ADC). It combines farletuzumab, a humanized IgG1 monoclonal antibody that targets the folate receptor alpha (FRα), with eribulin, an anticancer agent developed by Eisai. These components are linked using an enzymatically cleavable linker. Currently, three clinical studies are in progress: Eisai’s Phase 1/2 study for solid tumors (NCT04300556), and BMS's Phase 2 studies for ovarian, peritoneal and fallopian tube cancers (NCT05613088) and non-small cell lung cancer (NCT05577715).

Eisai has committed to refunding a portion of the $200 million payment received from BMS for research and development expenses under the initial collaboration agreement. The remaining amount will be recognized as other income.

Oncology is a significant focus area for Eisai, which aims to contribute to cancer cures by delving into human biology. The development of FZEC for refractory cancers highlights Eisai's dedication to meeting the unmet medical needs of cancer patients. The company is devoted to enhancing the benefits provided to cancer patients and their families.

FZEC, the company’s first ADC, combines farletuzumab, which binds to the FRα, with eribulin, employing an enzymatically cleavable linker. Upon entering FRα-positive cancer cells, the linker is expected to be cleaved enzymatically, releasing eribulin and triggering its antitumor activity. This separation inside targeted antigen-positive cancer cells is also theorized to have a bystander effect, impacting neighboring antigen-negative cancer cells and the tumor microenvironment. Pre-clinical studies have shown that FZEC exhibits a bystander effect, demonstrating antitumor activity on FRα-negative cancer cells surrounding FRα-positive cells.

Eribulin, the payload in FZEC, belongs to the halichondrin class of microtubule dynamics inhibitors. It is a simplified, synthetic version of halichondrin B, a natural substance isolated from the marine sponge Halichondria okadai. Eribulin works by inhibiting the growth phase of microtubule dynamics, thereby preventing cell division. It has been approved for use in the treatment of advanced breast cancer and liposarcoma in several countries, including Japan, the United States, China, and nations in Europe and Asia.

Eisai’s termination of the strategic collaboration with BMS underscores its commitment to advancing the development of FZEC independently. By reclaiming full rights to the drug, Eisai aims to accelerate its journey to market, providing hope for patients battling refractory cancers. This move aligns with Eisai's broader vision of exploring human biology to find innovative cancer treatments and improve the lives of patients worldwide.