This is 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, up to and including the Week 32 Visit, prior to the first dose of open-label KZR-616.~Patients will be 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 will receive 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 will end for all patients in Study KZR-616-003E when the last patient enrolled has completed 48 weeks of dose. Patients will have 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.
This is an open-label study to evaluate the long-term efficacy and safety of KZR-616 in patients with active PM or DM who completed the double-blind treatment period of Study KZR-616-003, up to and including the Week 32 Visit, prior to the first dose of open-label KZR-616.