Merck's Lung Cancer Drug I-DXd Fails to Clear Accelerated Approval Hurdle

Merck and Daiichi Sankyo have withdrawn their application for an accelerated approval of ifinatamab deruxtecan, or 'I-DXd', a lung cancer drug in development. The decision comes after the FDA indicated that response rates from Phase 2 testing were insufficient to warrant such clearance in extensive-stage small-cell lung cancer.

I-DXd targets the protein B7-H3, which is overexpressed in small-cell lung cancer. However, recent Phase 3 studies of similar drugs targeting this protein have shown promise and may be a new treatment standard for aggressive tumors. GSK's 'riz-rez' and Roche's 'tam-peli' are two such medicines that are being tested globally.

The FDA had expected to make a decision on I-DXd by October 10, but the companies have pulled their request after realizing it was unlikely to be approved. Merck is relying on emerging therapies to offset losses when Keytruda loses patent protection next decade.