Nine months of treatment with patisiran has been shown to enhance muscle mass in patients with hereditary transthyretin amyloidosis (hATTR), polyneuropathy, and the protein coding the transthyretin (TTR) gene, according to the results of a prospective study. Patisiran is a small interfering RNA that acts as a TTR silencer.
It is well recognized that the clinical phenotype of hATTR with polyneuropathy is heterogeneous, described as a multisystemic disease that affects sensorimotor and autonomic functions, along with other organs. Punctual and detailed instrumental biomarkers are in demand in patients with hATTR with polyneuropathy, in an effort to measure disease severity, along with progression and treatment response.
In this analysis, the researchers sought to characterize handgrip strength evaluated by handgrip measures and body composition evaluated through bioimpedance analysis (BIA), to detect early modification and response to patisiran therapy at 9 months of follow-up in patients with hATTR with polyneuropathy. The study was published in Biomedicines.
A total of 15 participants with hATTR with polyneuropathy were enrolled—6 male patients and 9 female patients. The average patient age was 66.4±7.8 years. Genetic testing confirmed a mutation in heterozygosis in the TTR gene in all of the participants. The most common symptoms reported included carpal tunnel syndrome in 80% of individuals, gastrointestinal disturbances in 60%, ataxia in 50%, and weight loss and autonomic dysfunction in 45%.
The study involved clinical and instrumental assessment of body weight and height, Coutinho stage, Neuropathy Impairment Score (NIS), NIS with muscle weakness (NIS-W), Karnofsky Performance Status (KPS), Norfolk Quality of Life (QOL) Questionnaire, Composite Autonomic Symptom Scale 31 (COMPASS -31), 6-minute walking test (6MWT), nerve conduction studies, handgrip strength, and bioimpedance analysis.
Learn more about hereditary transthyretin-mediated amyloidosis (hATTR)
Results of the study demonstrated that the body composition of the participants changed significantly following 9 months of patisiran treatment. Patients exhibited an increase in body cell mass, fat-free mass, and body weight, along with a decrease in fat mass. Additionally, following 9 months of therapy, a significant increase in 6MWT was observed (P =.033). Coutinho stage, KPS, NIS, NIS-W, nerve conduction studies, Norfolk QOL Questionnaire, COMPASS-31, and handgrip strength remained unchanged, however.
The handgrip test for measuring handgrip strength and the bioimpedance analysis are rapid, simple, and noninvasive tools that can be easily performed and do not require the use of expensive equipment.
“We believe that [handgrip strength] and [bioimpedance analysis] might find an application in clinical practice due to their low cost and high reliability,” the authors concluded. “Further studies are needed to confirm our findings and clarify a possible role of such tools in the diagnostic process [of hATTR with polyneuropathy].”
Reference
Di Stefano V, Thomas E, Alonge P, et al. Patisiran enhances muscle mass after nine months of treatment in ATTRv amyloidosis: a study with bioelectrical impedance analysis and handgrip strength. Biomedicines. 2023;11(1):62. doi:10.3390/biomedicines1101006
