Safety and Efficacy Study of OMS721 in Patients With Thrombotic Microangiopathies

A Phase 2, Uncontrolled, Three-Stage, Dose-Escalation Cohort Study to Evaluate the Safety, Pharmacokinetics, Pharmacodynamics, Immunogenicity, and Clinical Activity of OMS721 in Adults With Thrombotic Microangiopathies

The purpose of this study is to assess the safety, efficacy, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of OMS721 in patients with thrombotic microangiopathies (TMA).

This is a Phase 2, uncontrolled, 3-stage, ascending-dose-escalation study in patients with 1 of 3 forms of TMA: atypical hemolytic uremic syndrome (aHUS), thrombotic thrombocytopenia (TTP), and hematopoietic stem cell transplant - associated TMA (HSCT-associated TMA). In Stage 1 of the study, OMS721 was administered to 3 cohorts, with dose escalation by cohort to identify the optimal dosing regimen. In Stage 2, the dose selected in the first stage was administered to expanded cohorts of patients with distinct etiologies (aHUS alone in 1 cohort and TTP or HSCT-TMA in the other cohort). Patients completing Stage 2 were eligible for continued treatment in Stage 3 if they tolerated OMS721 treatment and derived clinical benefit. Enrollment in the study has been completed.

Inclusion Criteria:

1. Are at least age 18 at screening (Visit 1)
2. Have a diagnosis of primary aHUS, persistent HSCT-associated TMA or TTP
3. No clinically apparent alternative explanation for thrombocytopenia and anemia

Exclusion Criteria:

1. Had eculizumab therapy within three months prior to screening
2. Have STEC-HUS
3. Have a positive direct Coombs test
4. Have an active systemic bacterial or fungal infection requiring antimicrobial therapy (prophylactic antimicrobial therapy administered as standard of care is allowed)