BYM338/kg

Safety monitoring was conducted throughout the study. AEs starting on or after the day of first administration of extension study drug until last administration of study drug + 56 days are considered. SAEs starting on or after the day of first administration of extension study drug are considered. Deaths which occurred on or after the day of first administration of extension study drug are considered.

The 6MWD test measures the distance (in meters) that a participant can walk in a 6 minute time frame. A positive change from baseline indicates improvement. The efficacy analysis and time points were based on windowed visits relative to the first dose of the double-blind treatment in the core study.

Dual energy X-ray absorptiometry (DXA) was used to assess changes in body composition, including total fat and lean body mass (FM and LBM) and appendicular skeletal fat and muscle mass (aFM and aLBM). DXA instruments had a source that generated x-rays split into two energies which measured bone mineral mass and soft tissue from which fat and fat-free mass (or lean body mass) were estimated.

SPPB evaluates lower extremities in three functional components: maintenance of standing balance, usual gait speed and chair stand. Each test yields a score on a scale from 0 to 4 (total score 0-12, with the higher score reflecting a higher level of function).

SPPB evaluates lower extremities in three functional components: maintenance of standing balance, usual gait speed and chair stand. Each test yields a score on a scale from 0 to 4 (total score 0-12, with the higher score reflecting a higher level of function).

Change from Baseline in total Short Physical Performance Battery (SPPB) Score to week 25; SPPB is a series of six activities involving three domains of physical function - balance, usual walking speed and rising from a chair , is commonly used globally to assess and quantify (score 0-12) lower extremity function and has been shown to predict future adverse health events. A decline of one or more points in the SPPB total score is predictive of a decrease in lower extremity function and future adverse clinical outcomes in older adults, including falls, hospitalizations, institutionalization, incident disability and death

Mixed Model for Repeated Measures (MMRM) of change from baseline in total LBM (kg) by treatment and visit To assess dose-response relationship of bimagrumab and facilitate an adequate dose selection for future phase III studies, without the need for supportive data from another dose-response finding study, at least three doses were required, ranging from a non-effective or minimally effective dose to a dose where maximal efficacy is expected. Original study was initiated with only two doses of bimagrumab, therefore, a lower dose arm of 70mg has been added to this study with Amendment 2, changing the randomization ratio from 1:1:1 to 2:1:2:2 to either placebo, bimagrumab 70mg, bimagrumab 210mg, or bimagrumab 700mg. Since the 70mg dose was expected to show suboptimal efficacy and fewer patients were randomized to this group, it was used only for dose response modelling and not for hypothesis testing. Consequently, no efficacy evaluations for the bimagrumab 70mg Arm were performed

Any Adverse Event was defined as occurrence of any symptom regardless of intensity grade, Serious Adverse Event (SAEs) assessed as medical occurrences that result in death, are life threatening, require hospitalization or prolongation of hospitalization or result in persistent or significant disability/incapacity

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

Thigh Muscle Volume (TMV) change was evaluated by a responder analysis. Patients whose loss of muscle TMV by MRI was no more than or equal to 2% at Week 4,8,16 and 24 was considered responders.

Change in thigh muscle volume