Merck and Daiichi Sankyo Withdraw Cancer Drug Bid After FDA Signals Inadequate Data

Merck and Daiichi Sankyo have withdrawn their request for accelerated FDA approval of ifinatamab deruxtecan, or I-DXd, for adults with extensive-stage small cell lung cancer that has worsened after platinum chemotherapy. The companies said discussions with the FDA indicated the supporting data did not meet the requirements for accelerated approval.

The Phase 2 trial showed a confirmed response rate of 48.2% in patients who received the 12 mg/kg dose, but it lacked a control group to compare results against existing treatments. Side effects were significant, with 62% of patients on the higher dose experiencing grade 3 adverse events.

The next test is the Phase 3 IDeate-Lung02 trial, which compares I-DXd with a doctor's choice of chemotherapy in people whose cancer returned after one prior platinum-based treatment. Its primary goal is overall survival, and enrollment is near completion, according to Dr. Abderrahmane Laadem.

The withdrawal also sets back a major partnership between Merck and Daiichi Sankyo, with Merck paying $4 billion upfront in 2023 for rights to several experimental drugs, including I-DXd.