Merck, Daiichi pull lung cancer filing after FDA pushback deals another blow to $4B deal

$4 billion partnership hits a snag as Merck and Daiichi withdraw a lung‑cancer filing. The companies pulled a biologics license application for the B7‑H3 antibody‑drug conjugate Ifinatamab Deruxtecan, targeting previously treated extensive‑stage small‑cell lung cancer. Reuters and Fierce Biotech report the move followed pushback from the U.S. Food and Drug Administration, a surprise given the sizable joint venture.

Endpoints News and OncLive note the withdrawal eliminates the first U.S. submission for the therapy, while simplywall.st asks whether Daiichi Sankyo’s stock is now undervalued after the setback. The $4 billion joint deal depends on delivering a new treatment to a market with limited options. Investors and analysts view the pull as a direct hit to the financial expectations tied to the partnership. Patients waiting for a novel option for extensive‑stage small‑cell lung cancer lose a potential avenue, and both firms must reassess their regulatory roadmap.

Coverage does not detail immediate alternatives, but the companies may consider revised filings or different indications. Stakeholders will watch for any new filing announcements or statements from Merck and Daiichi addressing the next steps in the collaboration.