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Generic name:  melphalan flufenamide
Dosage form: lyophilized powder for injection
Drug class: Alkylating agents

Medically reviewed by  A Ras MD.

What is Pepaxto?

Pepaxto is a prescription medicine used in combination with the medicine dexamethasone to treat adults with multiple myeloma who did not respond to or stopped responding to at least four prior medicines including at least one proteasome inhibitor, one immunomodulatory agent and one CD38-directed antibody.

Pepaxto is not for use to prepare for transplant.

It is not known if Pepaxto is safe and effective in children.


Melphalan flufenamide is an alkylating drug. The chemical name is Ethyl (2S)-2-[[(2S)-2-amino-3-[4-[bis(2-chloroethyl)amino]phenyl]propanoyl]amino]-3-(4-fluorophenyl)propanoate hydrochloride and the molecular weight is 498.4 as free base and 534.9 as the hydrochloride salt. The structural formula is:

Chemical Structure

Melphalan flufenamide hydrochloride is soluble in most organic solvents, while sparsely soluble in aqueous solutions. The pKa value is 7.13.

PEPAXTO for injection is supplied as a sterile, white to off-white lyophilized powder in a single-dose vial for intravenous use. Each vial contains 20 mg melphalan flufenamide (equivalent to 21.48 mg melphalan flufenamide hydrochloride) and 1,000 mg sucrose.

 Mechanism of Action

Melphalan flufenamide is a peptide conjugated alkylating drug. Due to its lipophilicity, melphalan flufenamide is passively distributed into cells and thereafter enzymatically hydrolyzed to melphalan. Similar to other nitrogen mustard drugs, cross-linking of DNA is involved in the antitumor activity of melphalan flufenamide. In cellular assays, melphalan flufenamide inhibited proliferation and induced apoptosis of hematopoietic and solid tumor cells. Additionally, melphalan flufenamide showed synergistic cytotoxicity with dexamethasone in melphalan resistant and non-resistant multiple myeloma cell lines.

Who should not use Pepaxto?

Do not receive Pepaxto if you have a history of a severe allergic reaction to melphalan flufenamide or melphalan.

What should I tell my healthcare provider before using Pepaxto?

Before receiving Pepaxto, tell your healthcare provider about all of your medical conditions, including if you:

  • have an infection
  • are pregnant or plan to become pregnant. Pepaxto may harm your unborn baby.
    • Females who are able to become pregnant:
      • Your healthcare provider will check to see if you are pregnant before you start treatment with Pepaxto.
      • You should use an effective method of birth control (contraception) during treatment and for 6 months after the last dose of Pepaxto.
      • Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment with Pepaxto.
    • Males with female partners who are able to become pregnant:
      • You should use an effective method of birth control (contraception) during treatment and for 3 months after the last dose of Pepaxto.
      • Talk to your healthcare provider about effective methods of birth control that you can use during this time.
  • are breastfeeding or plan to breastfeed. It is not known if Pepaxto passes into breast milk. Do not breastfeed during treatment with and for 1 week after the last dose of Pepaxto.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

How should I use Pepaxto?

  • Pepaxto is given to you by your healthcare provider into your vein through intravenous (IV) infusion over 30 minutes.
  • Pepaxto is usually given 1 time every 28 days.
  • Your healthcare provider will decide how many treatments you need.
  • Your healthcare provider will do blood tests before and during your treatment with Pepaxto to check for side effects.
  • Your healthcare provider may prescribe medicines to help prevent nausea before your infusion and during treatment with Pepaxto.

What are the possible side effects of Pepaxto?

Pepaxto may cause serious side effects, including:

  • Low blood cell counts are common with Pepaxto and can be serious. Your healthcare provider will do blood tests as needed to check your blood cell counts during your treatment with Pepaxto.
    • Low platelet counts: Tell your healthcare provider right away if you have a bleeding or bruising under the skin.
    • Low red blood cell counts: Tell your healthcare provider if you are feeling weak, tired or you get tired easily, you look pale, or if you feel short of breath.
    • Low white blood cell counts: A low white blood cell count increases the risk of infections.
  • Infections. Pepaxto can cause infections that have led to death. Tell your healthcare provider right away if you develop new or worsening signs or symptoms of infection such as fever, chills, cough, pain, or burning during urination during treatment with Pepaxto.
  • Secondary cancers. New cancers such as myelodysplastic syndromes or acute leukemia have happened in people with multiple myeloma who have received Pepaxto. Your healthcare provider will monitor you for new cancers.

Your healthcare provider may change your dose of Pepaxto, stop your treatment for a period of time, or completely stop your treatment if you have certain side effects.

Pepaxto may cause fertility problems in males and females, which may affect your ability to have children. Talk with your healthcare provider if you have concerns about fertility.

The most common side effects of Pepaxto include, low blood cell counts, fatigue, nausea, diarrhea, fever, and cold-like symptoms (respiratory tract infection).

These are not all of the possible side effects of Pepaxto.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

General information about the safe and effective use of Pepaxto

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. You can ask your healthcare provider or pharmacist for information about Pepaxto that is written for health professionals.

What are the ingredients in Pepaxto?

Active ingredient: melphalan flufenamide

Inactive ingredient: sucrose




  • NDC 73657-020-01
    Rx only
  • Pepaxto®
    (melphalan flufenamide)
    for injection
  • 20 mg/vial
  • For Intravenous Infusion Only.
    Reconstitute and Dilute prior
    to administration.
  • Discard unused portion.
  • CAUTION: Hazardous Agent
  • One single-dose vial
  • 618133


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