Elrexfio (elranatamab-bcmm)
An approved treatment for Multiple Myeloma.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Elranatamab-bcmm wherever you encounter it, plus the key facts at a glance.
- Generic name
- Elranatamab-bcmm
- Brand name
- Elrexfio
- Development code
- PF-06863135
- Drug class
- BCMA-directed CD3 T-cell engager (bispecific antibody)
- Manufacturer
- Pfizer
- How it's taken
- Injection under the skin by a healthcare provider, starting with 2 step-up doses, then weekly, every 2 weeks and later every 4 weeks
Elrexfio (elranatamab-bcmm) is a bispecific antibody injection for adults whose multiple myeloma came back or stopped responding after at least 4 prior lines of therapy[1].
- The FDA granted Elrexfio accelerated approval on August 14, 2023, based on response rates, so continued approval may depend on a confirmatory trial[2][1].
- In the MagnetisMM-3 study, 57.7% of 97 people who had not had a prior BCMA therapy responded, and 25.8% reached a complete response or better[1].
- Elrexfio carries a boxed warning for cytokine release syndrome and neurologic toxicity, including ICANS, and is available only through the Elrexfio REMS program[1].
- Elrexfio is not approved for earlier lines of treatment, although Pfizer reported on April 29, 2026 that the MagnetisMM-5 trial in people with at least 1 prior line met its main goal[1][6].
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Where Elranatamab-bcmm fits
How Elranatamab-bcmm works
Elrexfio is a bispecific antibody, meaning one molecule has 2 different targets[1]. One end binds BCMA (B-cell maturation antigen) on plasma cells and myeloma cells, and the other end binds CD3 on T cells, the immune system's killer cells[1].
When Elrexfio links the 2 cells, the T cell switches on, releases inflammatory signals called cytokines and kills the BCMA-carrying myeloma cell[1]. That burst of T-cell activity is the reason the first doses are given in small steps with a hospital stay[1].
Side effects and safety
- Cytokine release syndrome. Occurred in 58%, mostly grade 1 or 2; most cases followed the first step-up dose (43%) or second step-up dose (19%).
- Neurologic toxicity including ICANS. Neurologic toxicity in 59% and ICANS in 3.3%; no driving for 48 hours after each of the 2 step-up doses and the first treatment dose.
- Infections. Serious infections in 42% and fatal infections in 7%; treatment is not started during an active infection.
- Neutropenia. Decreased neutrophils in 62%, grade 3 or 4 in 51%, and febrile neutropenia in 2.2%.
- Hepatotoxicity. Raised ALT in 36% and AST in 40%, with or without CRS.
- Embryo-fetal toxicity. May harm an unborn baby; effective birth control during treatment and for 4 months after the last dose.
- Hospital stay for 48 hours after step-up dose 1 and 24 hours after step-up dose 2
- Blood counts at the start and during treatment
- Liver enzymes and bilirubin at the start and during treatment
- Signs of infection before and during treatment, with preventive antimicrobials and antivirals per guidelines
- Signs of CRS and neurologic symptoms throughout treatment
Elrexfio has a boxed warning for cytokine release syndrome (CRS), an immune reaction that can cause fever, low blood pressure and low oxygen, and for neurologic toxicity, including ICANS (immune effector cell-associated neurotoxicity syndrome)[1]. In MagnetisMM-3, CRS occurred in 58% of people at the recommended dose, almost all grade 1 or 2, and most often after the first step-up dose[1]. Neurologic toxicity occurred in 59%, with grade 3 or 4 events in 7%, and ICANS in 3.3%[1].
Other serious risks on the label:
Fatal adverse reactions occurred in 10% of people in MagnetisMM-3, including pneumonia and sepsis[1]. Progressive multifocal leukoencephalopathy (PML), a rare brain infection, was added to the label's list of adverse reactions in February 2026[4][1].
The most common side effects were CRS (58%), tiredness (43%), injection site reactions (37%), diarrhea (36%), upper respiratory infections (36%) and muscle and bone pain (34%)[1]. Elrexfio may harm an unborn baby, and the label advises effective birth control during treatment and for 4 months after the last dose[1].
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Elranatamab-bcmm
Elrexfio is an injection under the skin given by a qualified healthcare professional, at fixed doses that do not depend on body weight[1].
The step-up schedule on the label:
About 1 hour before each of these first 3 doses, people receive acetaminophen 650mg, dexamethasone 20mg and diphenhydramine 25mg (or equivalents) to lower the risk of CRS[1].
After that, Elrexfio is 76mg weekly through week 24[1]. People who have responded (partial response or better) and kept that response for at least 2 months move to every 2 weeks, and those who keep responding for another 24 weeks move to every 4 weeks from week 49[1]. Treatment continues until the myeloma worsens or side effects become unacceptable[1].
Elrexfio is available only through the Elrexfio REMS, which requires certified prescribers, pharmacies and treatment sites and gives each patient a wallet card[1].
Availability and cost
Only available as the brand-name product.
Help paying for Elrexfio
With private insurance, the drugmaker's copay card can lower what you pay for Elrexfio. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE, but charity funds often can. Of the 5 charity funds for Multiple Myeloma, 1 was open on October 26, 2026. Without insurance, you can apply to the drugmaker's free medicine program, which sets its own eligibility rules. Pick your insurance below to see which offers fit you.
- Copay help
Eligible commercially insured patients may pay as little as $0 per Elrexfio treatment, regardless of income, up to $25,000 per calendar year. Not valid with Medicare, Medicaid, TRICARE, VA or other state or federal programs, or for cash-paying patients. Covers co-pays for Elrexfio given in the outpatient setting.
For: private insurance · source - Insurance and case manager help
A dedicated Patient Access Navigator helps with financial assistance options regardless of insurance, and helps people with Medicare, Medicaid or other government plans find independent funding resources. Call 1-877-744-5671, Monday through Friday, 8 AM to 8 PM ET.
For: private insurance, Medicare, Medicaid, no insurance · source - Free medicine program
Pfizer Oncology Together can check Medicaid eligibility for people with no coverage. People who do not qualify for Medicaid may receive free medicine through the Pfizer Patient Assistance Program, and must be eligible and reapply as needed.
For: no insurance · source
Good to know: The co-pay card is for patients 18 or older with private insurance that covers Elrexfio, and is accepted only at participating pharmacies. After the $25,000 yearly maximum, the patient pays the remaining out-of-pocket costs. Questions about the co-pay program itself go to 1-877-744-5675. Pfizer can change or end the program without notice, and terms expire at the end of each calendar year.
Charity funds for Multiple Myeloma
- From a charity · HealthWell FoundationMultiple Myeloma (Medicare Access) fundOpen
Pays for: Copays, premiums or other treatment costs. Medicare patients only.
Clinical trial results
MagnetisMM-3 (NCT04649359) was an open-label, single-arm study of Elrexfio alone in people whose myeloma was refractory to at least 1 proteasome inhibitor, 1 immunomodulatory agent and 1 anti-CD38 antibody[1][8]. The efficacy group was 97 people with no prior BCMA therapy and at least 4 prior lines of therapy[1].
Results from the label:
- Response: 57.7% responded, and 25.8% reached a complete response or better[1]
- Median time to first response was 1.22 months[1]
- Among responders, 90.4% were still responding at 6 months and 82.3% at 9 months[1]
- In 63 people who had already received a BCMA antibody-drug conjugate or BCMA CAR T therapy, 33.3% responded[1]
The MagnetisMM-3 results were published in Nature Medicine in September 2023[7].
MagnetisMM-5 (NCT05020236) is a randomized trial with 3 arms, Elrexfio alone, Elrexfio plus daratumumab, and daratumumab with pomalidomide and dexamethasone, in people whose earlier treatment included lenalidomide[9]. Pfizer said the trial enrolled 497 people, all previously treated with lenalidomide and a proteasome inhibitor, and its April 2026 result compared Elrexfio alone with daratumumab, pomalidomide and dexamethasone[6].
Pfizer announced on April 29, 2026 that the trial met its primary goal of longer progression-free survival at an interim analysis, with overall survival not yet mature[6]. Pfizer's announcement did not give the detailed numbers, and these results are not on the US label[6][1].
Development history
The FDA granted Elrexfio accelerated approval on August 14, 2023, together with the Elrexfio REMS[2][5].
Later label and REMS changes:
- July 10, 2025: the FDA approved the every-4-week dosing schedule for people who keep their response[3]
- February 19, 2026: progressive multifocal leukoencephalopathy was added to the adverse reactions section[4]
- March 25, 2026: a minor REMS update added an optional digital patient wallet card; the REMS itself stayed in place[5]
The indication is still an accelerated approval that depends on confirmatory trials[1]. Pfizer reported positive topline MagnetisMM-5 results on April 29, 2026 and said it would discuss them with health authorities[6].
Explore Multiple Myeloma trials
Other Multiple Myeloma treatments
Elrexfio is one of 4 FDA-approved bispecific T-cell engagers for myeloma; Tecvayli and Lynozyfic also target BCMA, while Talvey targets a different protein, GPRC5D[1][10][11][12]. All 4 labels carry the same type of boxed warning for CRS and neurologic toxicity and require a REMS program[1][10][11][12]. Elrexfio's label also reports responses in people who had already received a BCMA antibody-drug conjugate or CAR T therapy[1]. No trial has compared the bispecific antibodies with each other.
Common questions about Elranatamab-bcmm
▸What is Elranatamab-bcmm (Elrexfio)?
Elrexfio (elranatamab-bcmm) is a bispecific antibody injection for adults whose multiple myeloma came back or stopped responding after at least 4 prior lines of therapy[1]. The FDA granted Elrexfio accelerated approval on August 14, 2023, based on response rates, so continued approval may depend on a confirmatory trial[2][1]. In the MagnetisMM-3 study, 57.7% of 97 people who had not had a prior BCMA therapy responded, and 25.8% reached a complete response or better[1]. Elrexfio carries a boxed warning for cytokine release syndrome and neurologic toxicity, including ICANS, and is available only through the Elrexfio REMS program[1]. Elrexfio is not approved for earlier lines of treatment, although Pfizer reported on April 29, 2026 that the MagnetisMM-5 trial in people with at least 1 prior line met its main goal[1][6].
▸How does Elranatamab-bcmm work?
Elrexfio is a bispecific antibody, meaning one molecule has 2 different targets[1]. One end binds BCMA (B-cell maturation antigen) on plasma cells and myeloma cells, and the other end binds CD3 on T cells, the immune system's killer cells[1].
When Elrexfio links the 2 cells, the T cell switches on, releases inflammatory signals called cytokines and kills the BCMA-carrying myeloma cell[1]. That burst of T-cell activity is the reason the first doses are given in small steps with a hospital stay[1].
▸What are the side effects of Elranatamab-bcmm?
Elrexfio has a boxed warning for cytokine release syndrome (CRS), an immune reaction that can cause fever, low blood pressure and low oxygen, and for neurologic toxicity, including ICANS (immune effector cell-associated neurotoxicity syndrome)[1]. In MagnetisMM-3, CRS occurred in 58% of people at the recommended dose, almost all grade 1 or 2, and most often after the first step-up dose[1]. Neurologic toxicity occurred in 59%, with grade 3 or 4 events in 7%, and ICANS in 3.3%[1].
Other serious risks on the label: Infections: serious infections in 42%, grade 3 or 4 in 31% and fatal infections in 7%, most often pneumonia and sepsis[1] Low white blood cells: decreased neutrophils in 62%, grade 3 or 4 in 51%[1] Liver injury: raised liver enzymes in 36% to 40%[1]
Fatal adverse reactions occurred in 10% of people in MagnetisMM-3, including pneumonia and sepsis[1]. Progressive multifocal leukoencephalopathy (PML), a rare brain infection, was added to the label's list of adverse reactions in February 2026[4][1].
The most common side effects were CRS (58%), tiredness (43%), injection site reactions (37%), diarrhea (36%), upper respiratory infections (36%) and muscle and bone pain (34%)[1]. Elrexfio may harm an unborn baby, and the label advises effective birth control during treatment and for 4 months after the last dose[1].
▸How is Elranatamab-bcmm taken?
Elrexfio is an injection under the skin given by a qualified healthcare professional, at fixed doses that do not depend on body weight[1].
The step-up schedule on the label:
- Day 1: step-up dose of 12mg, followed by a 48-hour hospital stay[1]
- Day 4: step-up dose of 32mg, followed by a 24-hour hospital stay[1]
- Day 8: first full treatment dose of 76mg[1]
About 1 hour before each of these first 3 doses, people receive acetaminophen 650mg, dexamethasone 20mg and diphenhydramine 25mg (or equivalents) to lower the risk of CRS[1].
After that, Elrexfio is 76mg weekly through week 24[1]. People who have responded (partial response or better) and kept that response for at least 2 months move to every 2 weeks, and those who keep responding for another 24 weeks move to every 4 weeks from week 49[1]. Treatment continues until the myeloma worsens or side effects become unacceptable[1].
Elrexfio is available only through the Elrexfio REMS, which requires certified prescribers, pharmacies and treatment sites and gives each patient a wallet card[1].
▸Is Elranatamab-bcmm FDA approved?
Yes, Elranatamab-bcmm (Elrexfio) is FDA approved (2023) for the treatment of Multiple Myeloma.
▸How long is the hospital stay for Elrexfio?
The Elrexfio label calls for a 48-hour hospital stay after the first step-up dose and a 24-hour stay after the second[1].
Why: Most CRS happens early, after step-up dose 1 (43%) or step-up dose 2 (19%)[1].
Driving: The label advises no driving for 48 hours after each of the 2 step-up doses and the first treatment dose[1].
Source: Elrexfio prescribing information (DailyMed)
▸Can Elrexfio be given every 4 weeks?
Yes, since July 10, 2025, the label allows every-4-week dosing for people who keep responding[3].
Schedule: Weekly 76mg doses through week 24, then every 2 weeks for responders, then every 4 weeks from week 49[1].
Who: Moving to every 2 weeks requires a partial response or better lasting at least 2 months[1].
Source: Elrexfio prescribing information (DailyMed); FDA approval letter, BLA 761345/S-003
▸Does Elrexfio work after CAR T therapy?
The label reports a 33.3% response rate in 63 people who had already received a BCMA antibody-drug conjugate or BCMA CAR T therapy[1].
Comparison: In people with no prior BCMA therapy, the response rate was 57.7%[1].
Context: These were separate groups in a single-arm study, not a randomized comparison[1].
Source: Elrexfio prescribing information (DailyMed)
▸Is Elrexfio approved for earlier lines of myeloma treatment?
No, the current label covers only people who have had at least 4 prior lines of therapy[1].
Trial news: Pfizer said on April 29, 2026 that MagnetisMM-5, in people with at least 1 prior line, met its main goal at an interim analysis[6].
Status: Pfizer said it would discuss the results with health authorities; no earlier-line approval appears on the label[6][1].
Source: Elrexfio prescribing information (DailyMed); Pfizer, April 29, 2026
▸What side effects does Elrexfio cause?
The most common side effects on the label are CRS, tiredness, injection site reactions, diarrhea, upper respiratory infections and muscle and bone pain[1].
Serious: Serious infections occurred in 42% of people, and fatal infections in 7%[1].
Nerves: ICANS occurred in 3.3%, and broader neurologic toxicity in 59%[1].
Pregnancy: Effective birth control is advised during treatment and for 4 months after the last dose[1].
Source: Elrexfio prescribing information (DailyMed)
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed (Pfizer) · 2026-05. ELREXFIO (elranatamab-bcmm) injection, full prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=aa044060-5b4b-4692-bf0f-9a50e140b10e
- U.S. Food and Drug Administration · 2026-03-25. Drugs@FDA: ELREXFIO, BLA 761345, approval history. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=761345
- U.S. Food and Drug Administration · 2025-07-10. BLA 761345/S-003 supplement approval: every 4-week dosing regimen and REMS modification. https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2025/761345Orig1s003ltr.pdf
- U.S. Food and Drug Administration · 2026-02-19. BLA 761345/S-007 supplement approval: progressive multifocal leukoencephalopathy added to Adverse Reactions. https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2026/761345Orig1s007ltr.pdf
- U.S. Food and Drug Administration · 2026-03-25. BLA 761345/S-009 supplement approval: Elrexfio REMS modification. https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2026/761345Orig1s009ltr.pdf
- Pfizer · 2026-04-29. Pfizer's ELREXFIO Significantly Improves Progression-Free Survival for Double-Class Exposed Patients with Relapsed or Refractory Multiple Myeloma. https://www.pfizer.com/news/press-release/press-release-detail/pfizers-elrexfio-significantly-improves-progression-free
- Nature Medicine · 2023-09. Elranatamab in relapsed or refractory multiple myeloma: phase 2 MagnetisMM-3 trial results. https://doi.org/10.1038/s41591-023-02528-9
- ClinicalTrials.gov · 2026-11. MagnetisMM-3: Study Of Elranatamab (PF-06863135) Monotherapy in Participants With Multiple Myeloma Who Are Refractory to at Least One PI, One IMiD and One Anti-CD38 mAb. https://clinicaltrials.gov/study/NCT04649359
- ClinicalTrials.gov · 2026-11. A Study to Learn About the Study Medicine Elranatamab Alone and With Daratumumab in People With Multiple Myeloma Who Have Received Other Treatments (MagnetisMM-5). https://clinicaltrials.gov/study/NCT05020236
- U.S. National Library of Medicine, DailyMed (Janssen Biotech, Inc.) · 2026-04. TECVAYLI (teclistamab-cqyv) injection, full prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=54e0f974-ccee-44ea-9254-40e9883cee1e
- U.S. National Library of Medicine, DailyMed (Regeneron Pharmaceuticals) · 2025-07. LYNOZYFIC (linvoseltamab-gcpt) injection, full prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e9fd0739-1b3f-4b8b-824a-1f0a902384d3
- U.S. National Library of Medicine, DailyMed (Janssen Biotech, Inc.) · 2025-11. TALVEY (talquetamab-tgvs) injection, full prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9001355e-003d-4d4e-b4ce-337e0fd14952
- Pfizer · 2026-11. Co-pay Savings and Financial Support, Pfizer Oncology Together. https://www.elrexfio.com/financial-savings-and-support