Anti-HMGCR-Antibody-Positive Statin-Induced Myositis: A Pilot Case Series on Treatment with Bempedoic Acid and Immunosuppressive Therapy

Background/Objectives: Immune-mediated necrotizing myopathy (IMNM) is a severe inflammatory myopathy marked by proximal muscle weakness, elevated creatine kinase (CK), and the presence of anti-HMGCR antibodies. Statin exposure is a recognized trigger for anti-HMGCR-positive IMNM, which may persist despite statin withdrawal. This pilot case series explores, for the first time, the use of bempedoic acid—a liver-specific lipid-lowering agent with minimal muscle toxicity—as an alternative to statins in these patients. Methods: We report 10 anti-HMGCR-antibody-positive IMNM patients (6 females, 4 males) previously on statins for primary prevention (8 on atorvastatin, 2 on simvastatin) without prior cardiovascular events. Statins were discontinued at myositis onset. All patients received prednisone and immunosuppressants (methotrexate in 7, mycophenolate in 3), plus bempedoic acid. Anti-HMGCR antibodies were measured using a chemiluminescence method. Results: Their mean anti-HMGCR antibody levels decreased significantly from 390.93 ± 275.22 to 220.89 ± 113.37 CU/L (p = 0.027) after 6 months of treatment. Their CK levels dropped from 1278.9 ± 769.39 to 315.1 ± 157.72 IU/L (p = 0.001), and aldolase dropped from 11.63 ± 2.18 to 6.61 ± 1.22 U/L (p = 0.0001). The mean LDL-C value was 96.1 ± 8.16 mg/dL. No disease recurrence was observed. Autoimmune panels were negative for other myositis-associated and/or -specific antibodies. Conclusions: Bempedoic acid appears to be a safe, effective, and cost-efficient lipid-lowering alternative in statin-intolerant IMNM patients. Larger studies are warranted to confirm its efficacy across different subgroups and to optimize dyslipidemia management in this setting.