Merck, Daiichi Sankyo pull US lung cancer drug application

• The withdrawal followed discussions with the FDA, which found the mid-stage clinical study data insufficient to support accelerated approval
• The therapy targets extensive-stage small cell lung cancer, an aggressive condition, in adults who had progressed after standard chemotherapy treatment
• Both companies made the decision voluntarily to pull the application rather than face a formal rejection

Summary: Merck and Daiichi Sankyo Withdraw US Lung Cancer Drug Application

Key Development:

Merck and Daiichi Sankyo voluntarily withdrew their U.S. application for accelerated approval of ifinatamab deruxtecan, an experimental lung cancer therapy, on September 25. The withdrawal follows discussions with the FDA, which determined that data from a mid-stage clinical study did not meet requirements for early approval.

Drug and Indication:

Ifinatamab deruxtecan was being reviewed to treat adults with extensive-stage small cell lung cancer (SCLC), an aggressive condition, specifically targeting patients whose disease had progressed after standard chemotherapy treatment.

Companies Involved:

• Merck & Co (NYSE: MRK)
• Daiichi Sankyo Co Ltd

Market Implications:

This setback represents a significant development in the competitive oncology space, particularly for small cell lung cancer treatments. The withdrawal suggests the therapy's clinical data from mid-stage trials failed to demonstrate sufficient efficacy or safety to warrant the FDA's accelerated approval pathway, which typically requires strong evidence of clinical benefit.

The decision may impact both companies' near-term oncology pipelines and revenue projections, though the withdrawal is voluntary and may allow for potential resubmission with additional data. The extensive-stage SCLC indication represents a significant unmet medical need, as this patient population has limited treatment options after first-line chemotherapy failure.

Investors should monitor whether the companies plan to pursue additional studies or alternative regulatory pathways for this asset, as such decisions will influence long-term valuation of their oncology portfolios.