A first-of-its-kind antibody-drug conjugate for multiple myeloma, belantamab mafodotin-blmf (Blenrep) received accelerated approval from the U.S. Food and Drug Administration (FDA) in August 2020. The approval was based on clinical trial findings that demonstrated a 31% overall response rate that lasted at least six months in 73% of responders.
B-cell maturation antigen (BCMA)-directed antibody and microtubule inhibitor conjugate
Mechanism of Action
The antibody component is directed against BCMA, a protein expressed on multiple myeloma cells and normal B lymphocytes. The small molecule component, MMAF, is a microtubule inhibitor. Once belantamab mafodotin-blmf binds to BCMA, it is internalized and releases MMAF, which disrupts the microtubule network and leads to cell cycle arrest and cell death.
Adults with relapsed or refractory multiple myeloma who have previously received at least four therapies including an anti-CD38 monoclonal antibody, a proteasome inhibitor, and an immunomodulatory agent.
2.5mg/kg once every three weeks. Dose modifications may be necessary for corneal adverse reactions, infusion-related reactions, and thrombocytopenia.
IV infusion given over 30 minutes via a polyvinyl chloride (PVC) or polyolefin (PO) infusion set. Belantamab mafodotin-blmf should not be administered with other drugs.
Belantamab mafodotin-blmf has a black box warning and is available only through a REMS program. Changes in the corneal epithelium that affect vision, such as severe vision loss and corneal ulcer, have been reported. Symptoms may include blurred vision and dry eyes.
Additional warnings include thrombocytopenia, infusion related-reactions, and embryo-fetal toxicity. More than 20% of patients in clinical trials experienced keratopathy (corneal epithelium change), decreased visual acuity, nausea, blurred vision, pyrexia, infusion-related reactions, and fatigue. Laboratory abnormalities include decreased platelets, lymphocytes, hemoglobin, and neutrophils and increased creatinine and gamma-glutamyl transferase.
The potential for ocular toxicity requires additional nursing consideration and patient education. The REMS program requires patient enrollment and compliance with ongoing eye exams for ocular toxicity. Exams are required at baseline, prior to each dose, and upon any worsening eye symptoms.
Advise patients to avoid pregnancy and breastfeeding while on the medication and for four months (females) or six months (males) after the last dose; consider pregnancy test prior to initiating treatment. Belantamab mafodotin-blmf may impair fertility.
Educate patients about the potential for eye changes, including blurred vision, vision loss, and dry eyes. Initiate preservative-free lubricant eye drops four times daily with the first infusion and continue until the last dose. Avoid using contact lenses unless instructed by the ophthalmologist. Use caution when driving or operating heavy machinery because of the risk for vision changes.
Use effective birth control during treatment and for four months (females) or six months (males with female partners of childbearing potential) following the final dose. Report any unusual bleeding or bruising.
Data are limited regarding the effectiveness and response of patients aged 65 and older compared to younger populations.
Belantamab mafodotin-blmf is considered hazardous. Use safe handling and disposal procedures.
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