Immune-mediated necrotizing myopathies: clinico-serological features and treatment outcomes of a large Italian cohort of patients.

Authors

Silvia Bonanno, Erika Salvi, Marta Cheli, Franco Salerno, Matteo Lucchini, Alessandra Cicia, Vincenzo Carlomagno, Antonio Lauletta, Laura Tufano, Francesco Girolamo, Lucia Nicolini De Gaetano, Marco Fornaro, Elia Pancheri, Federico Zaottini, Elena Faedo, Patrizia Rovere Querini, Rebecca De Lorenzo, Marina Scarlato, Francesca Bottazzi, Pietro Riguzzi, Sara Gibertini, Barbara Risi, Alessia Pugliese, Dario Zoppi, Lucia Ruggiero, Giulia Ricci, Paolo Manganotti, Gabriele Siciliano, Carmelo Rodolico, Massimiliano Filosto, Luca Bello, Elena Pegoraro, Lorenzo Cavagna, Stefano Carlo Previtali, Chiara Fiorillo, Marina Grandis, Gaetano Vattemi, Paola Tonin, Florenzo Iannone, Giovanni Antonini, Matteo Garibaldi, Massimiliano Mirabella, Lorenzo Maggi

Published in

Journal of neurology. Volume 273. Issue 9. Aug 31, 2026. Epub Aug 31, 2026.

Abstract

Immune-mediated necrotizing myopathy (IMNM) is a distinct entity with limited large-cohort data. We aimed to characterize clinico-serological features and treatment outcomes of anti-SRP, anti-HMGCR, and seronegative IMNM in a large Italian cohort.
Retrospective multicenter study of adults diagnosed with IMNM (224th ENMC criteria) across 14 Italian neuromuscular centers between 2019 and 2022 was performed.
We included 159 subjects (57% female, median age 62 years): 40 SRP+, 71 HMGCR+, 41 seronegative, and 7 untested. SRP+ more frequently presented with proximal upper limb weakness and axial involvement versus HMGCR+ (OR = 3.89, padj = 0.007, OR = 3.47, padj = 0.04) and seronegative (OR = 4.00, padj = 0.014, OR = 15.2, padj = 0.005). Lung involvement was higher in SRP+ (7.5%), vs none in HMGCR+ and 2.4% in seronegative (p=0.028). Extramuscular features were more frequent in HMGCR+ (OR = 3.78, p = 0.019, padj = 0.057). SRP+ had higher odds of loss of motor independence (OR=4.22, padj =0.011) and relapse (OR = 14.4, padj = 0.010) than HMGCR+. Seronegative had better functional outcomes than SRP+ (p=0.047). Cancer associated myositis predicted worse disability (OR = 6.93, p = 0.0044). Overall, 71.7% improved with corticosteroids (OR=3.83, padj =0.01) and immunosuppressants (OR=2.296, padj =0.037), without serotype differences. CK decreased in 81.8% and normalized in 40.3% of patients; ΔCK was associated with improvement (p=0.017), clinical remission (p=0.002) and correlated with post-treatment functional scores (R=0.19, p= 0.044).
Subtype-specific differences and prognostic factors emerge. Exploratory functional assessment and ΔCK may capture treatment response in real-world settings.

PMID:
42671644
Bibliographic data and abstract were imported from PubMed on 01 Sep 2026.

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