Bristol Myers pays $650M for rights to Eisai's phase 1 ADC

Bristol Myers Squibb is paying $650 million to secure rights to Eisai’s folate receptor alpha-targeted antibody-drug conjugate (ADC) MORAb-202. The deal, which is worth up to $2.5 billion in milestones, sets Bristol Myers up to work with Eisai to get the drug into a registrational study next year.

Eisai created MORAb-202 by pairing an anti-folate receptor alpha (FRα) antibody with its anticancer agent eribulin. The idea is to use overexpression of the receptor in various malignancies to facilitate the targeted delivery of a therapeutic payload. The same concept underpins other ADCs such as Sutro’s STRO-002 and ImmunoGen’s once-failed phase 3 prospect mirvetuximab soravtansine.

Bristol Myers sees enough promise in MORAb-202 to bet big. Eisai is receiving $200 million to cover its R&D expenses and a further $450 million upfront payment, plus the promise of major milestones and royalties. In return, Bristol Myers has secured the right to jointly develop and commercialize the ADC with Eisai in North America, Europe, Russia, Japan, China and a clutch of other countries in the Asia Pacific region. Bristol Myers is solely responsible for MORAb-202 in the rest of the world. 

Eisai landed the deal after reporting data from a phase 1 clinical trial in 22 patients with FRα-positive solid tumors who failed to respond to standard therapy. After administering MORAb-202 at doses of 0.3 to 1.2 mg/kg once every three weeks, investigators saw one complete response and nine partial responses. Eight patients had stable disease. 

Japan’s Eisai is running that study in its home country while testing MORAb-202 in a separate phase 1/2 clinical trial in the U.S. Based on the evidence generated so far, Bristol Myers and Eisai are set to enter the registrational stage of development as early as next year. The partners are yet to disclose the target indications for the registrational work. FRα is overexpressed in cancers of the ovary, lung, breast and other organs. 

Other developers of FRα-targeted ADCs have identified opportunities to use their drug candidates in combination with checkpoint inhibitors such as Bristol Myers’ Opdivo. Sutro shared preclinical data on such a combination last year, while ImmunoGen’s mirvetuximab soravtansine is being studied in endometrial cancer patients in combination with Merck’s Keytruda.