How Elrexfio Works Against Multiple Myeloma
Elrexfio (elranatamab-bcmm) is a bispecific T-cell engager antibody that treats relapsed or refractory multiple myeloma by redirecting a patient's own T cells to attack cancer cells.[1] It binds to two targets: BCMA (B-cell maturation antigen) on myeloma cells and CD3 on T cells. This dual binding pulls T cells close to myeloma cells, triggering T-cell activation, release of cytotoxic proteins like perforin and granzymes, and destruction of the cancer cells through apoptosis.[1][2]
Administered as a subcutaneous injection after step-up dosing to manage cytokine release syndrome (CRS), Elrexfio activates the immune system selectively against BCMA-expressing plasma cells, sparing healthy cells with low BCMA levels.[1]
How Patients Receive Elrexfio Treatment
Treatment starts with subcutaneous step-up doses (e.g., 12 mg on day 1, 32 mg on day 4) followed by weekly 76 mg doses for the first two cycles, then every 2 weeks.[1] It's used after at least four prior therapies, including a proteasome inhibitor, immunomodulatory agent, and anti-CD38 antibody, in adults unresponsive to those or intolerant.[1][3]
Effectiveness in Clinical Trials
In the MagnetisMM-3 phase 2 trial, Elrexfio showed an overall response rate of 61% (CR or better in 35%) among heavily pretreated patients, with median progression-free survival not reached after 9 months.[1][4] Responses deepened over time, with 52% achieving minimal residual disease negativity at 10^-5 sensitivity.[4]
Common Side Effects and Management
CRS occurs in 57% of patients (mostly grade 1-2, median onset day 4), managed with supportive care like tocilizumab.[1] Other frequent issues include fatigue (50%), musculoskeletal pain (44%), and infections (44%). Neurotoxicity (ICANS) is rare (3%).[1][3] Premedication with dexamethasone, acetaminophen, and antihistamines reduces risks.
How Elrexfio Compares to Other BCMA-Targeted Therapies
Unlike CAR-T therapies (e.g., Abecma, Carvykti) requiring cell collection and infusion, Elrexfio is off-the-shelf with faster administration.[2] It matches bispecifics like Tecvayli (teclistamab) in response rates (63% ORR) but has a fixed-dose schedule after induction.[4] All target BCMA, but Elrexfio's subcutaneous route improves convenience over Tecvayli's IV.[3]
| Therapy | Type | ORR in R/R MM | Dosing |
|---------|------|---------------|--------|
| Elrexfio | Bispecific | 61% | SubQ, weekly then biweekly |
| Tecvayli | Bispecific | 63% | SubQ, weekly |
| Abecma | CAR-T | 73% | One-time IV infusion |
| Carvykti | CAR-T | 98% | One-time IV infusion |
[1]: FDA Label for Elrexfio
[2]: Pfizer Elrexfio Mechanism Overview
[3]: NEJM: MagnetisMM-3 Trial
[4]: ASCO 2023: Updated MagnetisMM-3 Data