The 6MWT measures how far a participant can walk in 6 minutes. Change from baseline was calculated as the difference between the distance walked during the 6MWT at 12 months and the distance walked during the 6MWT at baseline. To determine the baseline, at least 2 6MWTs were conducted \> 24 hours to ≤ 3 weeks apart prior to the first dose of ALXN2060. The baseline 6MWT is the average of the total distance walked by participants for the 2 qualifying 6MWTs that met all the protocol-defined criteria. Least squares mean change from baseline data were adjusted for baseline measures and visits.

CV-related hospitalization was defined as the mean number of CV-related hospitalizations per participant per year over a 30-month period. CV-related hospitalizations were also reported as adverse events and were reviewed and adjudicated by an independent Clinical Events Committee (CEC).

ACM was assessed as time from the date of first initiation of study treatment to the date of death during a 30-month period, and was analyzed using Kaplan-Meier analysis. Data are reported for the number of participants with ACM over the 30-month period.