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BCMA×CD3 Bispecific Antibody Pregnancy: Contraindicated — insufficient safety data; effective contraception required during and for 3 months after treatment

Elranatamab

Brand names: Elrexfio

Adult dose

Dose: Step-up: 12 mg SC (D1), 32 mg SC (D4); then 76 mg SC once weekly ×24 weeks; if CR/sCR ≥2 cycles: 76 mg every 2 weeks
Route: Subcutaneous injection
Frequency: Weekly (step-up then maintenance) → biweekly if in deep remission
Max: 76 mg per dose
Relapsed/refractory multiple myeloma ≥4 prior lines; step-up dosing mandatory to reduce CRS; hospitalisation required for first 2 step-up doses

Paediatric dose

Dose: Not established N/A/kg
Route: N/A
Frequency: N/A
Max: N/A
Not licensed in paediatrics

Dose adjustments

Renal

No dose adjustment required for CrCl ≥20 mL/min; limited data below

Hepatic

No formal adjustment required

Paediatric weight-based calculator

Not licensed in paediatrics

Clinical pearls

  • MagnetisMM-3 trial (Lesokhin et al. NEJM 2023): 61.1% overall response rate (58% ≥ VGPR) in heavily pre-treated penta-refractory myeloma — MHRA 2023 approved as first BCMA×CD3 SC bispecific in the UK
  • BCMA (B-cell maturation antigen) is highly expressed on myeloma cells — bispecific simultaneously binds BCMA on tumour cells and CD3 on T cells, forming an immunological synapse and inducing tumour cell lysis
  • CRS management protocol mandatory before prescribing: tocilizumab + corticosteroids must be available; monitor for 48 hours after step-up doses; subsequent doses can be given outpatient once tolerability established
  • Hypogammaglobulinaemia is universal with prolonged BCMA-directed therapy — immunoglobulin levels should be measured every 3 months; prophylactic IVIG (0.4 g/kg every 3-4 weeks) recommended for IgG <4 g/L or recurrent infections
  • MRD negativity achievable in deep responders; biweekly dosing option reduces treatment burden — clinically meaningful for heavily pre-treated patients often with poor performance status

Contraindications

  • Active uncontrolled infection
  • Known hypersensitivity
  • Prior severe CRS or ICANS with any bispecific

Side effects

  • Cytokine release syndrome (CRS — mostly grade 1-2 with step-up dosing)
  • ICANS/neurotoxicity
  • Infections (hypogammaglobulinaemia — IVIG replacement often required)
  • Injection site reactions
  • Neutropenia
  • Anaemia
  • Fatigue

Interactions

  • Corticosteroids — used prophylactically before each dose and to treat CRS; mandatory pre-medication
  • Live vaccines — avoid; profound immune suppression
  • Anticoagulants — thrombosis risk with myeloma; monitor

Monitoring

  • CRS assessment (each dose — vital signs, SpO₂, temperature)
  • ICANS grading (neurological check each dose)
  • FBC
  • Immunoglobulin levels (monthly)
  • Infection monitoring (FBC, CRP, cultures)
  • MRD testing at remission milestones

Reference: BNFc; BNF 90; MagnetisMM-3 trial (Lesokhin et al. NEJM 2023); MHRA SPC Elrexfio 2023; NICE appraisal in progress; Bahlis et al. ASH 2022. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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