Belantamab mafodotin is a cancer medicine used when other treatments for multiple myeloma have not worked. You usually receive it as an IV infusion at a clinic. The most serious risks involve your eyes, so close monitoring is required.
Brand Name(s)
- US: Blenrep
- Canada: Blenrep
Warning(s)
This drug can cause severe eye problems that may lead to vision changes or even loss of eyesight. You will have eye exams before starting and before each dose. Tell your care team right away if your vision worsens or you notice any new eye symptoms.
- Watch for eye symptoms: dry eyes, redness, pain or irritation, feeling like something is in the eye, light sensitivity, blurred vision, other vision changes.
- Use preservative-free lubricating eye drops as directed. Avoid contact lenses unless your doctor says it’s okay. Be careful with driving or tasks that need clear vision.
- Allergic reactions can happen. Get help right away for rash; hives; itching; swelling of the face, lips, tongue, or throat; chest tightness; wheezing; trouble breathing; or severe skin reactions.
- Bleeding risk: You may bruise or bleed more easily. Seek care for black or tarry stools, blood in urine, vomiting blood or coffee-ground material, bleeding you cannot stop, or unusual vaginal bleeding.
- Infection risk: Low white blood cell counts can occur. Call promptly for fever, chills, sore throat, or other signs of infection.
- Infusion reactions may occur during or soon after the infusion (fever, chills, flushing, fast heartbeat, cough, dizziness, severe headache, or fainting). Tell your nurse right away.
- Serious lung problems have happened rarely. Call if you have shortness of breath, cough, or fever.
- Other urgent symptoms: severe headache; weakness on one side; trouble speaking; balance changes; seizures; signs of high blood sugar (extreme thirst or hunger, frequent urination, fruity breath); or signs of electrolyte problems (muscle cramps/spasms, weakness, abnormal heartbeat).
- Pregnancy and breastfeeding: This drug may harm an unborn baby. You will have a pregnancy test before treatment. Use effective birth control while taking it and for 4 months after the last dose if you can become pregnant. If your partner can become pregnant, use birth control during treatment and for 6 months after the last dose. Do not breastfeed during treatment and for 3 months after the last dose.
- Fertility: This drug may affect the ability to become pregnant or father a child. Talk with your care team if this is a concern.
- Drug interactions: Tell your doctor and pharmacist about all medicines, vitamins, and herbal products you take. Do not start, stop, or change any medicine without checking first.
Kind of Cancers It Is Used For (not a complete list)
- Multiple myeloma that has come back (relapsed) or has not responded (refractory) after other treatments.
It is generally used when other medicines have not worked well enough. Your care team will decide if it’s appropriate for you based on your prior treatments and overall health.
Mechanism of Action
Belantamab mafodotin is an antibody–drug conjugate (ADC). It combines a lab-made antibody with a cancer-killing payload.
- The antibody part targets BCMA (B-cell maturation antigen), a protein found on most myeloma cells.
- Once attached, the ADC is taken into the cancer cell and releases the payload (a form of auristatin), which interferes with the cell’s internal structure and leads to cell death.
- Because BCMA is common on myeloma cells, this approach helps deliver the drug more directly to cancer cells. Eye side effects happen because some of the payload can affect cells on the surface of the eye.
Common Side Effects
Not everyone has side effects, and some are mild. Tell your care team if side effects bother you or do not go away. Call right away for symptoms listed in the warnings above.
- Eye problems: dry eyes, eye irritation, redness, blurred vision, light sensitivity.
- Feeling tired or weak.
- Upset stomach or diarrhea.
- Decreased appetite.
- Mild fever.
- Joint or back pain.
- Cold-like symptoms (such as runny or stuffy nose, sore throat).
Other effects may include low blood counts (which can raise your risk of infection or bleeding). Your care team will check your bloodwork regularly.
Tips to reduce risks:
- Use preservative-free artificial tears as directed.
- Avoid contact lenses unless your eye specialist says it is safe.
- Be careful to avoid cuts and injuries. Use a soft toothbrush and an electric razor.
- Report fever, chills, cough, shortness of breath, or any sudden change in vision right away.
Blenrep (belantamab mafodotin) Medline
Last reviewed: 2025-12-15
