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elranatamab
Elranatamab is a humanized, bispecific IgG2, T-cell engaging antibody targeting B-cell maturation antigen (BCMA) on multiple myeloma (MM) cells and CD3 on T-cells. Elranatamab binds to both BCMA and CD3, re-directing T-cells to BCMA-expressing MM cells. This leads to T-cell activation, proinflammatory cytokine release and multiple myeloma cell lysis.
| Bioavailability |
56.2% (subcutaneous) |
| T max |
3 to 7 days |
| Distribution Sites |
Central > peripheral compartment |
Expected to be metabolized into small peptides by catabolic pathways.
| Half-life |
22 days (at 76 mg dose level) |
- Multiple myeloma
(Includes conditional approvals)
Refer to the product monograph for a full list and details of approved indications.
Emetogenic Potential:
The following adverse events were reported in a Phase II, open-label study that evaluated patients with relapsed or refractory multiple myeloma (MM) who received elranatamab monotherapy, after 3 prior lines of therapy. These adverse effects were reported in ≥ 10% of patients in the trial; severe or life-threatening adverse events may also be included from other sources.
| ORGAN SITE | SIDE EFFECT* (%) | ONSET** | |||
|---|---|---|---|---|---|
| Cardiovascular | Arrhythmia (16%) (2% severe) | E | |||
| Dermatological | Rash, pruritus (26%) | E D | |||
| Gastrointestinal | Anorexia, weight loss (26%) | E | |||
| Constipation (14%) | E | ||||
| Diarrhea (36%) | E | ||||
| Nausea, vomiting (21%) | E | ||||
| General | Edema (18%) | E | |||
| Fatigue (43%) | E | ||||
| Hematological | Anemia (54%) (42% severe) | E D | |||
| Myelosuppression ± infection, bleeding (44%) (43% severe, 2% febrile neutropenia) (including opportunistic and reactivated viral infections) | E D | ||||
| Hepatobiliary | ↑ LFTs (16%) (5% severe) | E D | |||
| Immune | Cytokine release syndrome (58%) (< 1% severe) | I | |||
| ↓ Immunoglobulins (13%) | E D | ||||
| Injection site | Injection site reaction (37%) | I | |||
| Metabolic / Endocrine | Abnormal electrolyte(s) (21%) (↓ K) | E | |||
| Musculoskeletal | Musculoskeletal pain (22%) | E | |||
| Nervous System | Cognitive disturbance (14%) (including encephalopathy; 2% severe) | E | |||
| Guillain-Barre syndrome (<1%) | E | ||||
| Headache (18%) | E | ||||
| Immune effector cell-associated neurotoxicity syndrome (3%) | I E | ||||
| Insomnia (13%) | E | ||||
| Motor dysfunction (14%) (such as ataxia, balance disorder, gait disturbance, muscle weakness, tremor etc.) | E | ||||
| Sensory neuropathy (13%) | E | ||||
| Respiratory | Cough, dyspnea (24%) | E | |||
* "Incidence" may refer to an absolute value or the higher value from a reported range.
"Rare"
may refer to events with < 1% incidence, reported in post-marketing, phase 1 studies,
isolated data or anecdotal
reports.
** I = immediate (onset in hours to days)
E = early (days to weeks)
D = delayed (weeks to months)
L = late (months to years)
Refer to the T-Cell Engaging Antibodies guideline for a detailed description of CRS, ICANS and their management.
The most common side effects for elranatamab include cytokine release syndrome, anemia, myelosuppression ± infection, bleeding, fatigue, injection site reaction, diarrhea, anorexia, weight loss, rash, pruritus, cough, dyspnea and musculoskeletal pain.
Cytokine release syndrome (CRS) occurred in over half of patients treated with elranatamab. The majority were Grade 1 (44%), occurred after the first step-up dose (43%), and were single occurrences (recurrence in 13% of patients). Incidence of CRS decreased over the course of treatment (19% after second step-up dose, 7% after first treatment dose and 2% after subsequent doses) and onset ranged from 1 to 9 days (median 2 days) with a median duration of 2 days. Patients should be monitored for signs and symptoms of CRS after administration of step-up doses (e.g. for 48 hours after the dose). Symptoms reported include fever, hypoxia, chills, hypotension, tachycardia, headache, and elevated liver enzymes. Severe cases were uncommon, with 0.5% of patients experiencing Grade 3 and no Grade 4 CRS reported in the pivotal trial, however, CRS can be life-threatening and patients should be evaluated at the first sign of CRS for the need to hospitalize. Patients should receive treatment according to the recommended step-up schedule, with the appropriate premedications to reduce the incidence and severity of CRS. Tocilizumab or siltuximab were administered in 19% and corticosteroids in 9% of patients to treat CRS.
Neurological toxicity was observed in 59% of patients that received elranatamab in the clinical trial. The majority of cases were Grade 1 or 2 in severity, with Grade 3 or 4 events occurring in 7% of patients. Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) occurred in 3.3% of patients in the clinical trial, including recurrent events (1.1%); most patients experienced ICANS within the step-up dosing schedule (2.7% after the first step up dose). The median time to onset was 3 days, with a median duration of 2 days (range 1 to 18 days). ICANS may occur with or without the presence of CRS; the most frequent manifestations were depressed level of consciousness and declining ICE scores (Grade 1 or 2).
Serious infections occurred in 42% of patients that received elranatamab in the pivotal trial. Almost one third of patients had infections that were Grade 3 or 4 in severity, and 7% were fatal. This included opportunistic infections, such as PJP, PML, adenovirus infection, and hepatitis B and CMV reactivation. Hepatitis B reactivation has resulted in hepatic failure or death in some cases with other drugs that target B cells. Elranatamab treatment should not start in patients with active infections. Hypogammaglobulinemia occurred in 13% of patients with elranatamab; IV/Subcut immunoglubulin treatment should be considered as necessary, according to local practice guidelines. Infection precautions and antimicrobial prophylaxis should be instituted according to current local practice standards.
Refer to protocol by which patient is being treated.
Do not start treatment with elranatamab in patients with active infection.
Screen for hepatitis B virus in all cancer patients starting systemic treatment. Refer to the hepatitis B virus screening and management guideline.
Pre-medications (prophylaxis for CRS)
Administer 1 hour prior to the first 3 elranatamab doses* (step-up doses & first treatment dose):
- Acetaminophen 650 mg PO(or equivalent)
- Dexamethasone 20 mg PO or IV (or equivalent)
- Diphenhydramine 25 mg PO (or equivalent)**
*Assess the need for premedications with subsequent doses (see Table 3)
** Central nervous system (CNS) effects of diphenhydramine may make it challenging to identify ICANS. Consider cetirizine, which has a lower incidence of CNS effects.
Other Supportive Care:
- Consider prophylaxis against Pneumocystis jirovecii pneumonia (PJP) and herpes virus infections.
- Consider other antimicrobial prophylaxis as per local guidelines.
- Elranatamab should be administered to adequately hydrated patients.
Administer elranatamab using the following ramp-up dosing schedule to reduce the risk of CRS.
|
Cycle (28 days) |
Day* | Dose (mg, Subcut) | |
| Cycle 1 | Day 1 | 12 | Step-up Dose 1 |
| Day 4 | 32 | Step-up Dose 2 | |
| Day 8 | 76 | First Treatment Dose | |
| Day 15, 22 | 76 | Weekly dosing | |
| Cycle 2 to 6 | Day 1, 8, 15, and 22 | 76 | Weekly dosing |
| Cycle 7 and onwards | Day 1, and 15** | 76 | Every 2 week dosing** |
*Maintain a minimum of 2 days between Step-up dose 1 & 2, a minimum of 3 days between Step-up dose 2 & First Treatment Dose, and a minimum of 6 days between remaining treatment doses.
**Q2W schedule only if patients have achieved & maintained a partial response or better for at least 2 months.
Note: Inpatient admission may be required for CRS monitoring. ST-QBP funding for ambulatory administration only.
Dose reductions are not recommended.
Doses may be delayed due to toxicity. Recommendations on restarting after a dose delay are listed in Table 3.
Refer to the T-Cell Engaging Antibodies guideline for a detailed description of CRS, ICANS and their management.
Table 1 - CRS and ICANS Toxicity
| Toxicity | Gradea | Action |
|
CRS, or |
Grade 1 |
|
|
Grade 2 |
|
|
| Grade 3 |
|
|
|
Grade 4 |
|
a Grade based on American Society for Transplantation and Cellular Therapy (ASTCT) consensus grading (Lee et al 2019).
b Resume dose as recommended in Table 3.
c For daily monitoring, patients should remain within proximity of a healthcare facility.
Table 2 - Other Toxicity
| Toxicity | Severity | Action |
| Neutropenia | ANC < 0.5 × 109/L |
Hold* until ANC ≥ 0.5 × 109/L. |
| Febrile neutropenia | Any | Hold* until ANC ≥ 1 × 109/L and fever has resolved. |
| Thrombocytopenia | Platelets < 25 × 109/L | Hold* until platelets ≥ 25 × 109/L and no evidence of bleeding |
| Platelets 25 - 50 × 109/L with bleeding | ||
| Anemia | Hb < 80 g/L | Hold* until Hb ≥ 80 g/L. |
| Infection | Grade 3 | Hold* until resolves to Grade ≤ 1 or baseline. |
| Grade 4 |
Consider permanently discontinuing, OR Hold subsequent treatment doses (76 mg) until resolved to Grade ≤ 1 |
|
| Hypogammaglobulinemia | IgG < 4 g/L | Consider IV or Subcut immunoglobulin treatment, according to local guidelines |
| Other non-hematologic toxicity | Grade 3 | Hold* until resolves to Grade ≤ 1 or baseline. |
| Grade 4 |
Consider permanently discontinuing, OR Hold subsequent treatment doses (76 mg) until resolved to Grade ≤ 1 |
*Resume dose as recommended in Table 3.
Table 3 - Restarting Doses After Dose Delay
| Last Administered Dose | Duration of Delay | Action for Next Dose |
|
Step-up Dose 1 |
≤ 14 days | Administer premedications. Resume at 32 mg and continue step-up dosing schedule, if tolerated. |
| > 14 days | Administer premedications. Restart step-up dosing schedule at 12 mg. | |
|
Step-up Dose 2 |
≤ 14 days | Administer premedications. Resume at 76 mg. |
| 15 to 28 days | Administer premedications. Restart dosing at 32 mg and continue step-up dosing schedule, if tolerated. | |
| > 28 days | Administer premedications. Restart step-up dosing schedule at 12 mg. | |
|
Any Treatment Dose |
≤ 42 days | Resume at 76 mg. |
| 43 to 84 days | Administer premedications. Restart dosing at 32 mg and continue step-up dosing schedule, if tolerated. | |
| > 84 days | Administer premedications. Restart step-up dosing schedule at 12 mg. |
| Severity | Total Bilirubin | AST | Elranatamab Dose | |
| Mild | ≤ ULN | AND | > ULN | No dose adjustment |
| > 1 to 1.5 x ULN | AND | any | No dose adjustment | |
| Moderate or Severe | > 1.5 x ULN | AND | any | No data |
| Severity | Creatinine Clearance (mL/min) | Elranatamab Dose |
| Mild or Moderate | ≥ 30 | No dose adjustment |
|
Severe |
< 30 | Limited data |
No dose adjustment is required. No overall differences in safety or effectiveness were observed between patients ≥ 65 and ≥ 75 years of age (62% and 19% of patients in clinical trials, respectively) compared to younger patients.
No clinically relevant differences in PK were observed between white, Asian and Black groups.
The safety and efficacy of elranatamab in children have not been established.
- Elranatamab should be administered by subcutaneous injection only.
- Elranatamab vials do not require dilution. Refer to product monograph for details on preparation.
- Allow vials to come to room temperature before administration. Do not warm solution.
- Inject into abdomen (preferred); may be injected at other sites (e.g. thigh). Do not inject into areas where skin is red, bruised, scarred, tattooed or not intact.
- Monitor patients daily for 48 hours after administration of step-up doses for signs and symptoms of CRS or ICANS. Refer to the T-Cell Engaging Antibodies guideline for more information.
- Store unopened vials refrigerated (2°C to 8°C) and protect from light.
- Patients who are hypersensitive to this drug or to any of its components.
- Serious and life-threatening CRS and ICANS have occurred with elranatamab; ensure step-up schedule is followed and infusions are administered where there is immediate access to medications and equipment required to manage CRS and ICANS.
- Patients should avoid driving or operating heavy machinery for 48 hours following each dose in the step-up dosing schedule, or if any new neurological symptoms present due to the risk of a depressed level of consciousness from ICANS.
- Vaccination with live virus vaccines is not recommended for at least 4 weeks prior to, during and for at least 4 weeks after treatment with elranatamab. The risk of vaccine-associated infection may be increased or immune response to vaccines may be reduced.
- Patients with conditions such as active infection, stem cell transplant (within 12 weeks), history of Guillain-Barre syndrome, or sensory or motor neuropathy (Grade ≥ 2) were excluded from clinical trials; assess benefit-risk of elranatamab treatment in these patients.
Other Drug Properties:
-
Carcinogenicity:
Unknown
-
Genotoxicity:
Unknown
-
Fetotoxicity:
Probable
- Human IgG is known to cross the placenta after the first trimester of pregnancy and elranatamab may cause fetal harm based on its mechanism of action.
- Consider assessment of immunoglobulin levels in newborns of patients treated with elranatamab.
-
Pregnancy:
Elranatamab is not recommended for use in pregnancy. Adequate contraception should be used by patients and their partners during treatment, and for 5 months after the last dose.
-
Breastfeeding:
Breastfeeding is not recommended during treatment and for 5 months after the last dose.
-
Excretion into breast milk:
Probable
- Human IgG is known to be excreted in breast milk. The effects on breastfed infants and milk production are unknown.
-
Fertility effects:
Unknown
Elranatamab causes a transient release of cytokines that may suppress CYP450 enzymes and therefore increase exposure to CYP substrates. The highest risk of drug interactions is expected during the step-up dosing schedule, after the first dose (12mg) and up to 14 days after the second dose (32mg), and up to 7 days after a CRS event. Monitor patients receiving concomitant CYP450 substrates, especially those that have a narrow therapeutic index, for increased substrate concentrations or toxicity.
| AGENT | EFFECT | MECHANISM | MANAGEMENT |
|---|---|---|---|
| CYP 2C9 substrates (e.g. warfarin, meloxicam, fluvastatin) | ↑ substrate concentration and/or toxicity | cytokines may suppress CYP450 | Monitor and adjust dose of substrates with narrow therapeutic index (e.g. warfarin) if necessary |
| CYP3A4 substrates (e.g. cyclosporine, pimozide, tacrolimus, triazolo-benzodiazepines, dihydropyridine calcium-channel blockers, certain HMG-CoA reductase inhibitors) | ↑ substrate concentration and/or toxicity | cytokines may suppress CYP450 | Monitor and adjust dose of substrates with narrow therapeutic index (e.g. cyclosporine) if necessary |
Treating physicians may decide to monitor more or less frequently for individual patients but should always consider recommendations from the product monograph.
Refer to the hepatitis B virus screening and management guideline for monitoring during and after treatment.
Refer to the T-Cell Engaging Antibodies guideline for monitoring of CRS and ICANS during and after treatment.
| Monitor Type | Monitor Frequency |
|---|---|
CBC |
Baseline and before each dose; more frequently if clinically indicated |
Clinical toxicity assessment for CRS and ICANS |
Monitor frequently during and after ramp-up doses*; At each visit and as clinically indicated after ramp-up phase. |
Coagulation tests (e.g. aPTT, INR, PT, fibrinogen) |
Baseline and as clinically indicated |
CRP, ferritin |
Baseline and as clinically indicated |
LFTs, bilirubin |
Baseline and as clinically indicated |
Renal function tests |
Baseline and as clinically indicated |
Immunoglobulin levels |
As clinically indicated |
Clinical toxicity assessment for infection, bleeding, injection-site reactions, disseminated intravascular coagulation (DIC), rash, motor or sensory neuropath, pulmonary, cardiac and GI toxicity |
At each visit |
*Ramp-up doses are step-up dose 1, 2 and first treatment dose.
Grade toxicity using the current NCI-CTCAE (Common Terminology Criteria for Adverse Events) version
Canada’s Drug and Health Technology Agency. CADTH Reimbursement Recommendation Elranatamab (Elrexfio). Canadian Journal of Health Technologies. June 2024; 4 (6).
Crombie JL, Graff T, Falchi L, et al. Consensus recommendations on the management of toxicity associated with CD3×CD20 bispecific antibody therapy. Blood 2024; 143 (16): 1565–1575.
Elranatamab: Drug information. Waltham, MA: Lexi-Comp Inc., 2024. https://online.lexi.com. Accessed March 12, 2025.
Elrexfio (Elranatamab) Product Monograph. Pfizer Canada ULC. Kirkland, Quebec, December 2023.
Elrexfio (elranatamab-bcmm) Full Prescribing Information. Pfizer, Inc. New York, New York, August 2023.
Elrexfio Product information. Pfizer Europe. Bruxelles, Belgium, January 2024
Lee W, Santomasso BD, Locke FL, et al. ASTCT consensus grading for cytokine release Syndrome and neurologic toxicity associated with immune effector cells. Biol Blood Marrow Transplant. 2019;25:625-38.
Lesokhin AM, Tomasson MH, Arnulf B, et al. Elranatamab in relapsed or refractory multiple myeloma: phase 2 MagnetisMM-3 trial results. Nat Med. 2023 Sep;29(9):2259-67.
NCCN Practice Guidelines in Oncology (NCCN Guidelines) - Antiemesis v.2.2025. NCCN, May 2025. Accessed August 20, 2025.
Protocol for: Lesokhin AM, Tomasson MH, Arnulf B, et al. Elranatamab in relapsed or refractory multiple myeloma: phase 2 MagnetisMM-3 trial results. Nat Med. 2023 Sep;29(9):2259-67.
Rodriguez-Otero P, Usmani S, Cohen AD, et al. International Myeloma Working Group. International Myeloma Working Group immunotherapy committee consensus guidelines and recommendations for optimal use of T-cell-engaging bispecific antibodies in multiple myeloma. Lancet Oncol. 2024 May;25(5):e205-e216.
September 2025 New drug monograph
Refer to the New Drug Funding Program or Ontario Public Drug Programs websites for the most up-to-date public funding information.
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