Open-label Extension to the Phase 2 Crossover Study (PRESIDIO) Evaluating KZR-616 in Patients With PM and DM.

This was an open-label study to evaluate the long-term efficacy and safety of KZR-616 in patients with active polymyositis or dermatomyositis who completed the double-blind treatment period of Study KZR-616-003 (NCT04033926), up to and including the Week 32 Visit, prior to the first dose of open-label KZR-616. Patients were evaluated for eligibility according to the entry criteria at, or within 8 weeks after, the Week 32 Visit (ie, the End of Treatment \[EOT\] Visit \[Visit 34\]) of Study KZR-616-003. All patients received a subcutaneous (SC) injection of 30 mg KZR-616 at Visit 1 (Day 1), followed by weekly SC injections of 45 mg KZR-616 up to a maximum of 96 weeks. Study drug administration ended for all patients in Study KZR-616-003E when the last patient enrolled completed 48 weeks of dosing. Patients had a final follow-up visit 12 weeks after their last dose of KZR-616 (End of Study \[EOS\] Visit), for a maximum potential length of participation of 108 weeks.