Abstract Details

Title Exploring Demographic and Racioethnic Determinants of Phenotype and Treatment Response in Anti-HMGCR Myopathy

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P8 - Poster Session 8 (11:45 AM-12:45 PM)

Poster/Presentation
Number 9-019

Objective To explore demographic and racioethnic factors contributing to clinical phenotype and treatment response in patients with anti-HMGCR-positive immune-mediated necrotizing myopathy (IMNM).

Background IMNM is a rare inflammatory condition typically related to statin exposure. The demographic and racioethnic factors contributing to phenotypic heterogeneity and differential treatment responses in patients with IMNM are not fully understood.

Design/Methods This exploratory retrospective study investigated 25 patients with a diagnosis of IMNM seen between 2017 and 2025, including their demographic and disease-specific characteristics. We explored the number of immune therapy escalations (defined as addition of therapy or increase in dose/frequency) and hospitalizations related to IMNM.

Results We identified 25 patients with IMNM, with a mean age of 59.9 years±12.8 and of whom 48% were female. The overall mean time to diagnosis was 9.7±11.0 months, ranging from 7.9±12.44 months for White patients (7/25) to 12.1±11.43 months for Hispanic patients (8/25). At presentation, mean creatine kinase levels were higher in Black (11,000±1,414 U/L) and Asian (10,332±4,417 U/L), compared to White patients (6,528±2,730). Mean anti-HMGCR antibody levels were highest in Asian (280±97.3 U) and Hispanic (264.4±125.0 U) patients, compared to White (149±55.1 U) and Black patients (141±42.4 U). Therapy escalations were more frequent in male patients (2.91±2.21 vs. 1.36±1.03), patients under the age of 50 (3.20±2.17 vs. 1.94±1.92), and in Hispanic patients (2.89±1.83 vs. 0.75±0.50 in Asian patients). Hospitalizations related to IMNM were highest among Black patients (100%, 2/2), followed by Hispanic (50%, 5/10) and Asian patients (50%, 2/4), compared to 38% of White patients (3/8). These trends did not reach statistical significance (p > 0.05).

Conclusions This explorative study identified trends suggesting that demographic and racioethnic factors may influence phenotype and treatment response in IMNM. A larger study currently in process may elucidate these further.

Authors/Disclosures
Muhannad Seyam, MD (..) PRESENTER	Dr. Seyam has nothing to disclose.
Neelam Goyal, MD, FAAN (Stanford University)	Dr. Goyal has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Argenx. Dr. Goyal has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for UCB. Dr. Goyal has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Janssen. Dr. Goyal has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. The institution of Dr. Goyal has received research support from Argenx.
Lena Chaitesipaseut, PharmD, MBA	Mrs. Chaitesipaseut has nothing to disclose.
Claire Spahn, PharmD (Stanford Neuroscience Health Center)	Dr. Spahn has nothing to disclose.
Srikanth Muppidi, MD, FAAN	Dr. Muppidi has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Alexion. Dr. Muppidi has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for argenx. Dr. Muppidi has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for UCB/Ra Pharma. Dr. Muppidi has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Horizont Pharma. Dr. Muppidi has received personal compensation in the range of $500-$4,999 for serving as a Consultant for J & J pharma. Dr. Muppidi has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Dianthus Pharma. Dr. Muppidi has received publishing royalties from a publication relating to health care.

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