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Myasthenia Gravis: Eculizumab and Efgartigimod Therapy

Targeted biologic therapies for refractory generalized myasthenia gravis

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Nöroloji department. Book Appointment →

What is Myasthenia Gravis: Eculizumab and Efgartigimod Therapy?

Generalized myasthenia gravis is an autoimmune neuromuscular disease caused by antibodies against the acetylcholine receptor (AChR), MuSK or LRP4, leading to fatigable muscle weakness.

Eculizumab is a monoclonal antibody that inhibits complement protein C5, blocking complement-mediated destruction of the neuromuscular junction in AChR-positive gMG.

Efgartigimod is an Fc fragment that binds the neonatal Fc receptor (FcRn), increasing IgG catabolism and lowering pathogenic IgG autoantibodies including AChR antibodies.

Both are approved for adult AChR-positive gMG with inadequate response to traditional therapy (corticosteroids, azathioprine, mycophenolate, IVIG, plasma exchange).

These targeted therapies provide more rapid and selective immune modulation than broad immunosuppression.

Symptoms

Indications for biologic therapy: gMG with significant disability despite optimized standard immunotherapy, frequent myasthenic crises, intolerance to standard immunosuppressants
Pre-treatment symptoms: fatigable proximal limb weakness, ptosis, diplopia, dysphagia, dysarthria, respiratory weakness
On-treatment improvements: reduced fatigue, improved muscle strength, fewer crises, reduced steroid burden
Adverse effects: eculizumab — meningococcal infection risk (vaccinate beforehand), headache; efgartigimod — infusion reactions, headache, increased risk of certain infections
Monitor for breakthrough symptoms or treatment-related complications

Risk Factors

Patient selection: confirmed AChR-positive gMG with documented disability despite standard therapy
Eculizumab specific: meningococcal vaccination required (Neisseria meningitidis ACWY and B serogroups)
Considerations: pregnancy planning, infection history, financial considerations (high cost), monitoring requirements
Contraindications: active infection, untreated meningococcal exposure, severe renal/hepatic impairment may require dose adjustment

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Worsening myasthenic symptoms despite biologic therapy
  • Symptoms of myasthenic crisis: respiratory difficulty, severe weakness, swallowing difficulty
  • Signs of meningococcal infection (eculizumab): fever, headache, stiff neck, rash
  • Infusion reactions: rash, dyspnea, hypotension during or after administration
  • New or worsening infections during treatment
  • Pregnancy planning while on biologic therapy

Treatment Methods

01
Confirm AChR antibody-positive gMG with documented inadequate response to standard immunosuppression
02
Pre-treatment workup: comprehensive infection screening, baseline labs, clinical severity scales (MG-ADL, QMG)
03
Eculizumab: 900 mg IV weekly for 4 weeks, then 1200 mg IV every 2 weeks; meningococcal vaccination at least 2 weeks before starting plus penicillin prophylaxis if vaccination delayed
04
Efgartigimod: 10 mg/kg IV weekly for 4 doses (one cycle), repeated cycles based on clinical response (typically every 5–7 weeks)
05
Continue or taper concurrent immunosuppression based on response and tolerability
06
Monitor clinical scales (MG-ADL, QMG, MG composite) at regular intervals to assess response
07
Watch for adverse effects: monitor for meningococcal infection (eculizumab), infusion reactions, infection
08
Pregnancy planning: switch to plasma exchange/IVIG-based regimens before conception if possible
09
Reassess therapy after 6–12 months; consider continuing if benefit clear, alternative if inadequate response
10
Patient education on rescue plan for crisis: when to seek emergency care, contact information

Which Department to Visit?

You can visit our Nöroloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.