ELREXFIO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ELREXFIO (ELREXFIO).
ELREXFIO is a bispecific T-cell engager antibody that binds to B-cell maturation antigen (BCMA) on multiple myeloma cells and CD3 on T-cells, leading to T-cell activation and lysis of myeloma cells.
| Metabolism | ELREXFIO is a monoclonal antibody; expected to be degraded into small peptides and amino acids via catabolic pathways, not metabolized by CYP enzymes. |
| Excretion | ELREXFIO is a monoclonal antibody; expected to undergo catabolism to small peptides and amino acids. No active renal or biliary excretion. Elimination via reticuloendothelial system and target-mediated disposition. |
| Half-life | Terminal half-life approximately 7 days (range 5–9 days) in patients, supporting weekly or biweekly subcutaneous dosing. |
| Protein binding | Binds specifically to BCMA; no significant non-specific protein binding. Expected to be >95% bound to target cells. |
| Volume of Distribution | Volume of distribution approximately 4–6 L (0.06–0.08 L/kg), consistent with limited extravascular distribution typical of monoclonal antibodies. |
| Bioavailability | Subcutaneous administration: bioavailability approximately 60–80% relative to intravenous dosing. |
| Onset of Action | Clinical response (e.g., reduction in circulating plasma cells) observed within 2–4 weeks after first subcutaneous dose. |
| Duration of Action | Duration of therapeutic effect extends throughout the dosing interval (weekly or biweekly); continuous BCMA receptor engagement maintained with repeated doses. |
12 mg subcutaneously once weekly, after a 2-step step-up dosing schedule: 4 mg on week 1, 10 mg on week 2, then 12 mg weekly starting week 3.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (eGFR ≥30 mL/min). Safety and efficacy not established in severe renal impairment (eGFR <30 mL/min) or on dialysis. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh A). Not studied in moderate (Child-Pugh B) or severe (Child-Pugh C) hepatic impairment; use with caution. |
| Pediatric use | Safety and efficacy not established in pediatric patients (<18 years). |
| Geriatric use | No specific dose adjustment recommended for elderly patients. Consider monitoring for increased toxicity due to age-related decline in organ function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ELREXFIO (ELREXFIO).
| Breastfeeding | Unknown if elranatamab is excreted in human milk. Human IgG is present in breast milk, but M/P ratio not determined. Due to potential for adverse reactions in breastfed infants (e.g., immunosuppression), advise women not to breastfeed during treatment and for 5 months after last dose. |
| Teratogenic Risk | ELREXFIO (elranatamab) is a bispecific BCMA-directed CD3 T-cell engager. There are no adequate data on use in pregnant women. Based on its mechanism of action, T-cell activation and cytokine release may affect fetal development. Human IgG crosses the placenta; fetal exposure is expected. Potential risks include fetal B-cell depletion and immunological effects. First trimester: unknown risk. Second and third trimesters: potential for fetal harm. Contraindicated unless benefit outweighs risk. |
■ FDA Black Box Warning
Cytokine release syndrome (CRS) and neurologic toxicity, including immune effector cell-associated neurotoxicity syndrome (ICANS), which can be severe or life-threatening.
| Serious Effects |
None known.
| Precautions | Cytokine release syndrome (CRS), neurologic toxicity (including ICANS), infections, neutropenia, hepatotoxicity, and embryo-fetal toxicity. |
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| Fetal Monitoring | Monitor for cytokine release syndrome (CRS), neurological toxicities, infections, cytopenias, and liver function abnormalities. In pregnant women, monitor fetal growth and development via ultrasound. Assess for signs of fetal B-cell depletion (e.g., low immunoglobulin levels). Perform serial blood counts and inflammatory markers. |
| Fertility Effects | No human data on fertility effects. In animal studies, no direct reproductive toxicity studies; however, based on mechanism (immune modulation), potential for impaired fertility due to cytokine effects on gonadal function. Effects likely reversible after treatment cessation. |