Open Label Controlled Trial of Eculizumab in Adult Patients With Plasma Therapy-sensitive Atypical Hemolytic Uremic Syndrome (aHUS)

• Additional efficacy endpoints related to manifestations of TMA. [ Time Frame: Through 26 weeks ] [ Designated as safety issue: No ]
• Overall safety and tolerability of eculizumab [ Time Frame: Through 26 weeks ] [ Designated as safety issue: Yes ]
• Pharmacokinetics (PK) and pharmacodynamics (PD) of eculizumab in patients with aHUS. [ Time Frame: Through 26 weeks ] [ Designated as safety issue: Yes ]

The purpose of this study is to determine whether eculizumab is safe and effective in the treatment of adult patients with plasma therapy-sensitive Atypical Hemolytic-Uremic Syndrome (aHUS).

Inclusion Criteria:

1. Male or female patients ≥18 years of age who have been diagnosed with Atypical Hemolytic-Uremic Syndrome (aHUS).
2. Patients must be receiving PT for aHUS.
3. Platelet Count Pre-PT Baseline Set-Point (collected immediately prior to the Qualifying PT Episode) is within 75% of the average of the pre-PT platelet counts collected at Screening and during the Observation Period.
4. Diagnosis of aHUS
5. Lactate dehydrogenase (LDH) level ≥ ULN.
6. Creatinine level ≥ ULN for age.
7. Sexually active women of childbearing potential must be practicing an effective, reliable and medically acceptable contraceptive regimen during the entire duration of the study, including the follow-up period.
8. Able to give written informed consent.
9. Able and willing to comply with study procedures.

Exclusion Criteria:

1. ADAMTS-13 inhibitor or deficiency (i.e., ADAMTS-13 activity <5%) as measured at the screening visit.
2. Malignancy.
3. Typical HUS (Shiga toxin +).
4. Known HIV infection.
5. Identified drug exposure-related HUS.
6. Infection-related HUS.
7. Presence or suspicion of active and untreated systemic bacterial infection that, in the opinion of the Investigator confounds an accurate diagnosis of aHUS or impedes the ability to manage the aHUS disease.
8. Pregnancy or lactation.
9. Unresolved meningococcal disease.
10. Known Systemic Lupus Erythematosus (SLE) or antiphospholipid antibody positivity or syndrome.
11. Any medical or psychological condition that, in the opinion of the investigator, could increase the patient's risk by participating in the study or confound the outcome of the study.
12. Patients receiving IVIg or Rituximab therapy.
13. Patients receiving other immunosuppressive therapies such as steroids, mTOR inhibitors or FK506 inhibitors are excluded unless: [1] part of a post-transplant anti-rejection regime, [2] patient has confirmed anti-CFH antibody requiring immunosuppressive therapy and [3] dose of such medications have been unchanged for at least 4 weeks prior to the screening period.
14. Patients receiving Erythrocyte Stimulating Agents (ESAs) unless already on a stable dose for at least 4 weeks prior to the screening period.
15. Participation in any other investigational drug trial or exposure to other investigational agent, device, or procedures beginning 4 weeks prior to screening and throughout the entire trial.