Management of immune-mediated necrotizing myopathy

Area of Science:

• Neurology
• Immunology
• Rheumatology

Background:

• Immune-mediated necrotizing myopathies (IMNM) are autoimmune disorders causing muscle weakness and elevated creatine kinase (CK).
• IMNM can be associated with specific autoantibodies (anti-HMGCR, anti-SRP), statin use, cancer, or be idiopathic.
• Current treatment lacks FDA-approved therapies, leading to significant practice variation in management.

Purpose of the Study:

• To review current understanding of IMNM management.
• To explore subtype-specific treatment responses and optimal immunotherapy strategies.

Main Methods:

• Review of observational studies and expert opinions on IMNM treatment.
• Analysis of treatment responses based on serological subtypes (HMGCR, SRP, seronegative).

Main Results:

• HMGCR-associated IMNM often responds well to intravenous immunoglobulin (IVIG) monotherapy.
• Signal recognition peptide (SRP) and seronegative IMNM typically require combination immunotherapy (e.g., oral immunosuppressants, corticosteroids, IVIG/rituximab).
• Patients frequently require long-term immunotherapy, with common relapses during tapering.

Conclusions:

• Optimal management strategies for IMNM are still under investigation.
• Subtype-specific immunotherapy approaches show promise but require further validation.
• Long-term treatment and relapse prevention are key challenges in IMNM care.