Safety and tolerability of phenylbutyrate in inclusion body myositis

Authors

  • Duaa Jabari Cedars Sinai
  • Andrew Heim University of Kansas Medical Center
  • Ali Ciersdorff University of Kansas Medical Center
  • Heather Wilkins University of Kansas Medical Center
  • Abdulbaki Agbas Kansas City University
  • Edina Kosa Kansas City University
  • Suzanne Hunt University of Kansas Medical Center
  • Mamatha Pasnoor University of Kansas Medical Center
  • Mazen Dimachkie University of Kansas Medical Center
  • Richard Barohn University of Missouri

DOI:

https://doi.org/10.17161/rrnmf.v5i1.21356

Keywords:

Inclusion body myositis, phenylbutyrate

Abstract

Introduction

Phenylbutyrate (PBA) showed positive effect on the muscle cell model of Inclusion Body Myositis (IBM) by improving lysosomal activity, ameliorating consequences of impaired autophagy, and decreasing vacuolization. This provides rationale to study this medication in patients with IBM.

Objectives

To evaluate the safety and tolerability of phenylbutyrate in IBM, and monitor for any early signal of effectiveness.

Methods

Open-label study of 10 subjects with IBM who received treatment with PBA for 3 months after a 3-month run-in period. The PBA dose was 3 gm twice daily. The primary outcome measure was adverse event reporting. Secondary outcome measures included manual muscle testing, timed up and go test, IBM functional rating scale, and grip strength, along with exploratory biomarkers evaluating the mitochondrial function, stress response, degenerative process, and apoptosis.

Results

Ten subjects completed the study. PBA was well tolerated with no serious adverse events related to it. The most common adverse events were gastrointestinal related and did not require stopping treatment. One of the biomarkers (MitoTracker) showed a statistically significant drop over the treatment period of the study (p-value of 0.02 for the mean change). There were no statistically significant changes in other secondary outcome measures, but the study was limited by a small sample size and short treatment period.

Conclusions

Phenylbutyrate was safe and well tolerated in patients with IBM in this pilot study. The change in the MitoTracker suggests target engagement, but a Phase II study is needed to confirm and study the efficacy of PBA in IBM

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Published

2024-03-01

Issue

Section

New Discoveries and Original Research

How to Cite

Jabari, D., Heim, A., Ciersdorff, A., Wilkins, H., Agbas, A., Kosa, E., Hunt, S., Pasnoor, M., Dimachkie, M., & Barohn, R. (2024). Safety and tolerability of phenylbutyrate in inclusion body myositis. RRNMF Neuromuscular Journal, 5(1). https://doi.org/10.17161/rrnmf.v5i1.21356