Pronunciation: Blen-rep
Generic name: belantamab mafodotin-blmf
Dosage form: single-dose powder for reconstitution and further dilution (100 mg)
Drug class: Miscellaneous antineoplastics

Medically reviewed by Carmen Pope, BPharm. Last updated on July 25, 2025.

What is Blenrep?

Blenrep is used to treat relapsed or refractory (r/r) multiple myeloma (MM) in adults who have received at least 4 prior medicines, including an anti-CD38 monoclonal antibody, a proteasome inhibitor, and an immunomodulatory agent.

Blenrep works by combining an antibody (afucosylated IgG1) that targets a protein called BCMA found on normal B lymphocytes and multiple myeloma cells, with MMAF, a microtubule inhibitor drug. When Blenrep binds to myeloma cells, it is internalized and MMAF is released, disrupting the microtubule network, leading to cell cycle arrest and cell death through multiple mechanisms.

Blenrep belongs to the drug class called B-cell maturation antigen (BCMA)-directed antibody and microtubule inhibitor conjugates. The BCMA pathway is important for myeloma cell growth and survival.

Blenrep (mafodotin-blmf) first gained FDA approval for r/r MM on August 5, 2020, under the accelerated approval designation. In November 2022, GSK withdrew Blenrep from the U.S. market after the DREAMM-3 phase 3 confirmatory trial failed to meet its endpoints.

Review of Blenrep Combinations in Multiple Myeloma

Recently, GSK, the manufacturer of Blenrep, applied to the US FDA advisory committee for approval of Blenrep in combination with bortezomib and dexamethasone in r/r MM patients who have received at least one prior therapy, and in combination with pomalidomide and dexamethasone in r/r MM patients who have received at least one prior therapy, including lenalidomide.

The FDA voted against the overall benefit/risk profile at the proposed dosage of Blenrep combinations and has extended the review period to October 23, 2025, in order to review additional information provided in support of the application.

The regulatory submission is supported by phase 3 DREAMM-7 and DREAMM-8 clinical trials showing statistically significant progression-free survival improvements for Blenrep combinations versus standard triple therapies, with DREAMM-7 also demonstrating superior overall survival compared to daratumumab-based treatments.

Blenrep combinations are currently approved in the UK, Japan, Switzerland, and the EU.

Side effects

The most common side effects of Blenrep are:

• vision or eye changes, such as findings on eye exam (keratopathy)
• decreased vision or blurred vision
• nausea
• low blood cell counts (such as low platelets, lymphocytes, hemoglobin, and neutrophils)
• fever
• infusion-related reactions
• tiredness
• changes in kidney or liver function blood tests.

Related/similar drugs

Serious side effects and warnings

Blenrep carries a Boxed Warning for eye problems (ocular toxicity).

Eye problems:

Eye problems are common with Blenrep. Blenrep can cause changes to the surface of your eye that can lead to dry eyes, blurred vision, worsening vision, severe vision loss, and corneal ulcer. Tell your healthcare provider if you have any vision changes or eye problems during treatment with Blenrep.

• Your healthcare provider will send you to an eye specialist to check your eyes before you start treatment with Blenrep, prior to each dose of Blenrep, and for worsening symptoms of eye problems.
• Even if your vision seems fine, you must get your eyes checked during treatment with Blenrep because some changes can happen without symptoms and may only be seen on an eye exam.
• You should use preservative-free lubricant eye drops at least 4 times per day during treatment with Blenrep as instructed by your healthcare provider.
• You should use caution when driving or operating machinery, as Blenrep may affect your vision.
• Avoid wearing contact lenses during treatment with Blenrep unless directed by your eye specialist.

Because of ocular toxicity, Blenrep is only available through a restricted program, called the Blenrep REMS. Before you receive Blenrep, you must read and agree to all of the instructions in the Blenrep REMS. Before prescribing Blenrep, your healthcare provider will explain the Blenrep REMS to you and have you sign the Patient Enrollment Form.

Other serious side effects

Blenrep can cause other serious side effects, including:

• A decrease in platelets (thrombocytopenia) is common with Blenrep and can also be serious. Platelets are a type of blood cell that help your blood clot. Your healthcare provider will check your blood cell counts before you start treatment with Blenrep and during treatment. Tell your healthcare provider if you have bleeding or bruising during treatment with Blenrep.
• Infusion reactions are common with Blenrep, and can also be serious. Tell your healthcare provider or nurse right away if you get any of the following signs or symptoms of an infusion reaction while receiving Blenrep:
  • chills or shaking
  • fever
  • redness of your face (flushing)
  • feel like your heart is racing (palpitations)
  • itching or rash
  • shortness of breath, cough, or wheezing
  • swelling of your lips, tongue, throat, or face
  • dizziness
  • feel like passing out
  • tiredness.

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

These are not all the possible side effects of Blenrep. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800­ FDA-1088.

Before receiving

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

• have a history of vision or eye problems.
• have bleeding problems or a history of bleeding problems.
• are pregnant or plan to become pregnant
• are breastfeeding or plan to breastfeed.

Pregnancy

Blenrep can harm your unborn baby. Females who can become pregnant:

• Your healthcare provider may do a pregnancy test before you start treatment with Blenrep. You should use effective birth control during treatment with Blenrep and for 4 months after the last dose. Talk to your healthcare provider about birth control methods you can use during this time.
• Tell your healthcare provider if you become pregnant or think you may be pregnant during treatment with Blenrep.

Males with female partners who can become pregnant should use effective birth control during treatment with Blenrep and for 6 months after the last dose.

Breastfeeding

It is not known if Blenrep passes into your breast milk. Do not breastfeed during treatment with Blenrep and for 3 months after the last dose.

Fertility

Blenrep may affect fertility in males and females. Talk to your healthcare provider if this is a concern for you.

How is Blenrep administered?

Blenrep is administered as an intravenous infusion over approximately 30 minutes once every 3 weeks.

• It will be given to you by your healthcare provider, who will decide how many treatments you need.
• Your healthcare provider may decrease your dose, temporarily stop, or completely stop treatment with Blenrep if you have serious side effects.
• If you miss any appointments, call your healthcare provider as soon as possible to reschedule your appointment.

What other drugs will affect Blenrep?

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

Ingredients

Active Ingredient: belantamab mafodotin-blmf

Inactive Ingredients: citric acid, disodium edetate dihydrate, polysorbate 80, trehalose dihydrate, trisodium citrate dihydrate.

Manufacturer

Blenrep (belantamab mafodotin-blmf) is manufactured by GlaxoSmithKline Intellectual Property Development Ltd., England Brentford, Middlesex, UK TW8 9GS.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer