{"classes":[{"categories":[{"measurements":[{"groupId":"OG000","value":"7"},{"groupId":"OG001","value":"2"}]}],"title":"Pre-Existing ADA"},{"categories":[{"measurements":[{"groupId":"OG000","value":"11"},{"groupId":"OG001","value":"3"}]}],"title":"Treatment Emergent ADA"},{"categories":[{"measurements":[{"groupId":"OG000","value":"5"},{"groupId":"OG001","value":"2"}]}],"title":"Treatment Emergent Neutralizing ADA"}],"denoms":[{"counts":[{"groupId":"OG000","value":"153"},{"groupId":"OG001","value":"76"}],"units":"Participants"}],"description":"Number of participants with positive ADA prior to taking study drug and/or during study. A participant was counted as \"treatment-emergent\" if there was a positive post-baseline sample while the baseline sample was ADA negative, or there was a positive post-baseline sample with a titer ≥ 4-fold of the baseline titer while the baseline sample was ADA positive. A participant was counted as \"preexisting\" if the baseline sample was ADA positive and the participant was not qualified for \"treatment-emergent.\"","groups":[{"description":"Luspatercept 1.0 mg/Kg SC on Day 1 of each 21-day treatment cycle","id":"OG000","title":"Luspatercept"},{"description":"Placebo (Volume equivalent to experimental arm) SC on Day 1 of each 21-day treatment cycle","id":"OG001","title":"Placebo"}],"paramType":"COUNT_OF_PARTICIPANTS","populationDescription":"Safety population of participants with ADA samples collected.","reportingStatus":"POSTED","timeFrame":"From randomization to 1 year post first dose","title":"Participants With Pre-Existing and/or Treatment-Emergent Antidrug Antibodies (ADA)","type":"SECONDARY","unitOfMeasure":"Participants"}