A 25-year-old woman has relapsing-remitting multiple sclerosis (RRMS). She has had 2 clinical relapses in the past year and a new T2 lesion on MRI. She is concerned about treatment efficacy. Which first-line disease-modifying therapy has the highest relapse rate reduction (approximately 68%) with parenteral administration?
- A Interferon beta-1a (Avonex) — weekly IM injection, ~30% reduction
- B Glatiramer acetate — daily SC injection, ~29% reduction
- C Natalizumab — monthly IV infusion, ~68% reduction ✓
- D Dimethyl fumarate — oral twice daily, ~49% reduction
Explanation
Natalizumab (anti-alpha-4 integrin monoclonal antibody) inhibits lymphocyte trafficking across the blood-brain barrier and reduces annualised relapse rate by approximately 68% — among the highest of approved RRMS therapies. It is given as monthly IV infusion. The main risk is progressive multifocal leukoencephalopathy (PML) from JC virus reactivation, particularly in JC antibody-positive patients after prolonged use. Interferon beta and glatiramer acetate provide ~30% reduction; dimethyl fumarate ~49%; high-efficacy agents (natalizumab, alemtuzumab, ocrelizumab) provide 60-80% reduction.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.