IPM Take
This is healthy regulation, not failed innovation. Small-cell lung cancer desperately needs new treatments, and ifinatamab deruxtecan remains promising. But an objective response rate in a single-arm study should not automatically become a market authorisation. The Phase III trial is almost enrolled. Let the harder evidence answer the harder question.
Executive Summary
Merck and Daiichi Sankyo announced the voluntary withdrawal of the U.S. biologics license application seeking accelerated approval for ifinatamab deruxtecan, a B7-H3-directed antibody-drug conjugate, in extensive-stage SCLC after progression on or after platinum chemotherapy. The companies said FDA concluded that the supporting evidence, including the Phase II IDeate-Lung01 trial, did not satisfy requirements for accelerated approval. Development continues, with enrollment nearing completion in the randomized Phase III IDeate-Lung02 trial. In the published IDeate-Lung01 analysis, the 12-mg/kg cohort produced a 48.2% confirmed objective response rate, median response duration of 5.3 months, median PFS of 4.9 months and median OS of 10.3 months. Treatment-related interstitial lung disease occurred in 12.4%, including grade 3 or higher events in 4.4%.
Why it matters
- Patients / advocates: Urgency for new SCLC options cannot justify uncertainty being hidden.
- Regulators: Accelerated approval still requires evidence strong enough to support reasonable confidence in benefit.
- Clinicians: The ADC remains investigational; Phase III results will now matter decisively.
- Industry: A promising response rate does not guarantee a regulatory shortcut.
Small-cell lung cancer creates exactly the kind of pressure that can weaken evidentiary discipline.
The disease is aggressive. Relapse is common. Options after platinum chemotherapy remain inadequate. When a novel ADC produces responses in almost half of heavily pretreated patients, the instinct is understandable: move.
FDA effectively said: not yet.
Merck and Daiichi Sankyo have withdrawn their accelerated-approval application for ifinatamab deruxtecan after discussions with the agency made clear that the current package was insufficient.
That does not mean the drug does not work.
IDeate-Lung01 produced a confirmed response rate of 48.2% at the selected dose. But median response lasted 5.3 months, median PFS was 4.9 months, and treatment-related ILD was a real safety issue.
Those are promising numbers.
They are also precisely the kind of numbers a randomized trial needs to put into context.
The Phase III IDeate-Lung02 trial compares the ADC against physician-choice chemotherapy in relapsed disease. Enrollment is nearing completion. If the drug is genuinely practice-changing, that study has a chance to show it.
Accelerated approval is valuable because some patients cannot wait years for conventional evidence generation. But the pathway only survives politically if “accelerated” does not become “automatic.”
A regulatory no can protect innovation as much as a yes.
This one says: bring stronger evidence.
That is a reasonable demand.
