Melphalan flufenamide (Pepaxto)

Key facts

• Pepaxto is not currently FDA-approved in the United States.
• The withdrawn approval involved melphalan flufenamide with dexamethasone for certain heavily pretreated adults with relapsed or refractory multiple myeloma.
• Melphalan flufenamide is different from melphalan; similar names should not be treated as interchangeable.
• Patients should discuss current treatment options with a licensed oncology team and should not use this page to start, stop, or change treatment.

What the FDA decided

The FDA granted accelerated approval to melphalan flufenamide in February 2021. Accelerated approval can require a later study to verify that a medicine provides clinical benefit.

On February 23, 2024, the FDA issued its final decision withdrawing the approval. The agency stated that the confirmatory study did not confirm clinical benefit and that the available evidence did not show the medicine to be safe or effective under its conditions of use.

What melphalan flufenamide is

Melphalan flufenamide is a peptide-drug conjugate related to the alkylating medicine melphalan. It was developed to enter cells and release melphalan after enzymatic processing.

The NCI Drug Dictionary still maintains a scientific definition and terminology entry. A dictionary entry does not mean that a medicine currently has FDA approval or is appropriate for a particular person.

Why the current status matters

Older articles, trial records, and archived prescribing information may still describe the 2021 accelerated approval. Anyone researching this medicine should check the publication date and verify the current regulatory status with the FDA.

Clinical trials may continue to study an agent after an approval is withdrawn. Trial availability is separate from FDA approval and does not establish that a treatment is safe, effective, or appropriate for an individual.

Questions to ask an oncology team

• Is the source I found describing an old approval, an active clinical trial, or current standard care?
• How is melphalan flufenamide different from melphalan?
• What currently approved options and clinical trials apply to this disease setting?
• Where can I verify the latest FDA status and trial information?

Primary sources

• FDA: withdrawn melphalan flufenamide accelerated approval — FDA page documenting the original accelerated approval and the February 2024 withdrawal decision.
• FDA: withdrawn cancer accelerated approvals — FDA table listing Pepaxto and its withdrawal date.
• NCI Drug Dictionary: melphalan flufenamide hydrochloride — Scientific definition, synonyms, and mechanism terminology from the National Cancer Institute.