Conditions: Sporadic Inclusion Body Myositis
Keywords: sporadic inclusion body myositis, muscle wasting, extension study, BYM338, bimagrumab,
Allocation: NON_RANDOMIZED | Intervention model: PARALLEL
Enrollment: 211
Healthy volunteers: no

Brief summary:
This extension study will provide data to further evaluate the efficacy, safety, and tolerability of three doses of BYM338 and to assess the long-term effects of BYM338 in patients with sporadic inclusion body myositis. The extension study was planned to consist of a Screening epoch (to assess patient eligibility), followed by a Treatment Period 1 epoch (double-blind and placebo-controlled), and a Treatment Period 2 epoch (open-label). A Post-treatment Follow-up (FUP) epoch was also planned for patients who discontinued prematurely. Patients who complete the core study and qualify for this extension study entered Treatment Period 1 and continued on the study drug to which they were randomized in the core study (either to one of the three bimagrumab doses (1 mg/kg, 3 mg/kg, and 10mg/kg) or placebo) during Treatment Period 1. Thus, Treatment Period 1 was double-blind and placebo-controlled. Participants were to continue in Treatment Period 1 until the dose with the best benefit-risk profile was determined from the core study data and selected (duration of Treatment Period 1 was estimated to be between 6 and 8 months). Once the dose with the best benefit-risk profile was selected, all participants (including those who were receiving placebo) were planned to enter Treatment Period 2 and switch to open-label treatment with bimagrumab at the selected dose. The core study has been completed but since the core study did not meet the primary end point (no bimagrumab dose was identified based on the core study efficacy results) the extension study was terminated as per protocol/sponsor's decision; therefore, no patients had entered Treatment Period 2. Instead, all patients were to return for the End of Treatment Period 1 (EOT1) visit at their next scheduled visit. As per protocol, all patients who discontinued study medication during Treatment Period 1 for any reason, including due to the study having been stopped as per protocol/sponsor's decision, were to have entered and complete the 6-month FUP after their EOT1 visit.

Due to the nature of the design of the core and extension studies and termination of study medication in the extension study, the treatment duration for individual patients varied considerably. Consequently, the number of patients contributing data to the efficacy analyses at Week 104 and later timepoints was decreased.

Detailed description:

Arms:
arm 1: Participants received BYM338 10 mg/kg administered via intravenous infusion every 4 weeks for up to a maximum of 8 months after which they entered a 6-month, treatment-free follow-up period. arm 2: Participants received BYM338 3 mg/kg administered via intravenous infusion every 4 weeks for up to a maximum of 8 months after which they entered a 6-month, treatment-free follow-up period. arm 3: Participants received BYM338 1 mg/kg administered via intravenous infusion every 4 weeks for up to a maximum of 8 months after which they entered a 6-month, treatment-free follow-up period. arm 4: Participants received placebo administered via intravenous infusion every 4 weeks for up to a maximum of 8 months after which they entered a 6-month, treatment-free follow-up period.

Interventions: intervention 1: Bimagrumab intervention 2: Placebo
Intervention descriptions: intervention 1: BYM338, a 150 mg/mL concentrate for solution for i.v. infusion, was provided in colorless glass vials with a rubber stopper and aluminum flip-off caps. intervention 2: Matching placebo to BYM338 was provided in colorless glass vials with a rubber stopper and aluminum flip-off caps.

Protocol document: