The 6MWD test measured the distance (in meters) that a participant walked in a 6 minute timeframe. A positive change from baseline indicates improvement.

The Full Analysis Set (FAS), which included all randomized participants who had received at least one dose of study drug and had at least one post-baseline efficacy assessment, was considered for the analysis. Only those participants from the FAS who had both baseline and week 52 6MWD measurements were analyzed.

LBM was measured via dual energy x-ray absorptiometry (DXA) and calculated as (LBM at Week 52/LBM at baseline)*100 . A positive change from baseline indicates improvement.

The Full Analysis Set (FAS), which included all randomized participants who had received at least one dose of study drug and had at least one post-baseline efficacy assessment, was considered for the analysis. Only those participants from the FAS who had both baseline and week 52 LBM measurements were analyzed.

Quadriceps muscle strength was measured by portable fixed dynamometry (PFD) on the right side. A negative change from baseline indicates deterioration.

The Full Analysis Set (FAS), which included all randomized participants who had received at least one dose of study drug and had at least one post-baseline efficacy assessment, was considered for the analysis. Only those participants from the FAS who had both baseline and week 52 QMT measurements were analyzed.

Self-reported physical function was assessed by a newly developed patient reported outcome named sporadic inclusion body myositis (sIBM) functional assessment (sIFA). The sIFA consists of 11 items scored on an 11 point numerical rating scale from 0 (no difficulty) to 10 (unable to do) across 3 domains: upper body functioning, lower body functioning and general functioning. Participants completed the assessment where the recall period was the past week prior to completing the patient reported outcome (PRO). The total score on the sIFA scale ranges from 0 (minimum) to 110 (maximum). Higher values represent a worse outcome. A positive change from baseline indicates deterioration.

The Full Analysis Set (FAS), which included all randomized participants who had received at least one dose of study drug and had at least one post-baseline efficacy assessment, was considered for the analysis. Only those participants from the FAS who had both baseline and week 52 sIFA measurements were analyzed.

Participants documented any fall occurrences in a paper diary during the study.

The Full Analysis Set (FAS), which included all randomized participants who had received at least one dose of study drug and had at least one post-baseline efficacy assessment, was analyzed.

The SPPB evaluated lower extremities function by testing gait speed, ability to keep standing balance and time to rise from a chair five times. The sub-score for each test ranged from 0 to 4. The summary score, which was a summation of scores from the 3 tests, ranged from 0 to 12. An increase in score indicates improvement in physical performance. A negative change from baseline indicates deterioration.

The Full Analysis Set (FAS), which included all randomized participants who had received at least one dose of study drug and had at least one post-baseline efficacy assessment, was analyzed.