Inclusion Body Myositis

PURPOSE OF REVIEW This article highlights the clinical and diagnostic features of inclusion body myositis (IBM) and provides recent insights into the pathomechanisms and therapeutic strategies of the disease.

RECENT FINDINGS IBM is an often-misdiagnosed myopathy subtype. Due to the insidious onset and slow progression of muscle weakness, it can often be dismissed as a sign of aging as it commonly presents in older adults. While challenging to recognize upon initial clinical evaluation, the recent recognition of specialized stains highlighting features seen on muscle pathology, the use of diagnostic tools such as the anti-cytosolic 5’-nucleotidase 1A antibody biomarker, and the ability of muscle imaging to detect patterns of preferential muscle involvement seen in IBM has allowed for earlier diagnosis of the disease than was previously possible. While the pathogenesis of IBM has historically been poorly understood, several ongoing studies point toward mechanisms of autophagy and highly differentiated cytotoxic T cells that are postulated to be pathogenic in IBM.

SUMMARY Overall advancements in our understanding of IBM have resulted in improvements in the management of the disease and are the foundation of several strategies for current and upcoming novel therapeutic drug trials in IBM.

Address correspondence to Dr Namita Goyal, UC Irvine-MDA ALS and Neuromuscular Center, 200 S Manchester Ave, Ste 110, Orange, CA 92868, [email protected].

RELATIONSHIP DISCLOSURE: Dr Goyal has received personal compensation in the range of $500 to $4999 for serving on a scientific advisory or data safety monitoring board or on a speakers bureau for Abcuro, Alexion Pharmaceuticals, Annexon, argenx, AstraZeneca, CSL Behring, Kezar Life Sciences, Sanofi, and UCB. The institution of Dr Goyal has received research support from Alexion Pharmaceuticals, Amylyx, Anelixis Pharmaceuticals, Annexon, BrainStorm Cell Therapeutics, Cytokinetics, Fulcrum Therapeutics, the HEALEY ALS Platform Trial, Kezar Life Sciences, MediciNova, Mitsubishi Tanabe Pharma, and Transposon Therapeutics. Dr Goyal has received publishing royalties from a publication relating to health care.

UNLABELED USE OF PRODUCTS/INVESTIGATIONAL USE DISCLOSURE: Dr Goyal reports no disclosure.