This ONS resource was produced for educational purposes only. Refer to the full elranatamab-bcmm (Elrexfio™) package insert for all details.

Classification Immunotherapy; bispecific T-cell engager/bispecific antibody
Mechanism of Action Binds to BCMA on plasma cells, plasmablasts, and multiple myeloma cells and to CD3 on T cells, causing cytokine release and leading to lysis of multiple myeloma cells  
Indication Adults with relapsed or refractory multiple myeloma who received at least four prior lines of therapy, including a proteasome inhibitor, immunomodulatory agent, and anti-CD38 monoclonal antibody 
Dosing, Frequency,
and Duration
Day Dose
1 Step-up dose 1: 12 mg 
4 Step-up dose 2: 32 mg 
8 First treatment dose: 76 mg 
One week after first treatment dose and weekly thereafter through week 24  Subsequent treatment doses: 76 mg
Week 25 and every two weeks thereafter 
Route Subcutaneous injection
Safe Handling Elranatamab-bcmm is a potentially hazardous drug per the National Institute for Occupational Safety and Health definition because of its embryo-fetal toxicity. Follow safe-handling precautions
  • Decreased lymphocytes, neutrophils, hemoglobin, white blood cells, and platelets
  • Upper respiratory tract infection, pneumonia, and cough 
  • Diarrhea, decreased appetite, and nausea 
  • Fatigue, musculoskeletal pain, and pyrexia 
  • Rash 
  • Injection site reaction 
  • Cytokine release syndrome (CRS) 
Black box warnings: CRS and neurologic toxicity, including immune effector cell–associated neurotoxicity syndrome (ICANS)
Other warnings: infections, neutropenia, hepatotoxicity, and embryo-fetal toxicity 
  • Verify patients’ pregnancy status and monitor complete blood cell counts, liver enzymes, and bilirubin at baseline and regularly throughout treatment. 
  • Administer premedications (acetaminophen 650 mg orally, dexamethasone 20 mg orally or via IV, and diphenhydramine 25 mg orally) one hour prior to each dose in the step-up schedule, including the first treatment dose. 
  • Elranatamab-bcmm is available only through a REMS program; provide patients with a wallet card at the start of treatment. 
  • The abdomen is the preferred injection site. 
  • In the drug’s clinical trial, CRS occurred in 58% of patients; median time to onset was two days but developed up to nine days after dose administration. 
  • In the clinical trial, neurologic toxicity occurred in 59% of patients (ICANS in 3.3%); median time to onset of ICANS was three days after dose administration.   
  • Patients require hospitalization for 48 hours after the first step-up dose and 24 hours after second step-up dose. 
  • CRS and ICANS can occur concurrently, subsequently, or in the absence of each other. 
  • Report fever or signs of infection, neurologic symptoms (e.g., dizziness, confusion, changes in consciousness), shortness of breath, jaundice, dark urine, and abdominal pain.  
  • Delayed onset of CRS or ICANS is possible; seek immediate evaluation if you develop symptoms. 
  • Avoid pregnancy or breastfeeding during treatment and for four months after your last dose. 
  • Carry a wallet card at all times and present it to all healthcare providers. 
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