Phase IIa Trial of ALXN1007 for the Treatment of Non-criteria Manifestations of Antiphospholipid Syndrome

Enrollment discontinued early due to recruitment difficulties. Initially enrolled patients
will complete the study.

Inclusion Criteria:

Patients with a persistent and clinically significant aPL profile

Patients with at least 1 of the following non-criteria manifestations of APS:

1. aPL-nephropathy (diagnosed by kidney biopsy within 12 months of Screening) confirmed
based on the updated APS Classification Criteria recommendations, and urine protein
to creatinine ratio > 1.0 at the time of the Screening visit and/or

2. Skin ulcers (non-infected livedoid vasculitis-like skin ulcer and/or large skin
ulceration resembling pyoderma gangrenosum) for at least 4 weeks prior to the
Screening visit, diagnosed by physical examination, and/or

3. Persistent active thrombocytopenia (diagnosed by platelet counts <100 x 103/μL and
≥20 x 103/μL [SI: <100 x 109/L and ≥ 20 x 109/L]) and confirmed at the time of
screening (at least 4 weeks after previous test) based on the updated APS
Classification Criteria recommendations Patients and spouse/partner who is of
childbearing potential must be using highly effective contraception consisting of 2
forms of birth control (at least 1 of which must be a barrier method) starting at
Screening and continuing through the entire study.

Patients with aPL-nephropathy must be receiving or agree to initiate an ACE inhibitor or
angiotensin receptor blocker at least 4 weeks prior to initiation of ALXN1007 treatment;
unless patient is documented to be intolerant. Patients receiving oral corticosteroids
must be on a stable dose of ≤ 10 mg/day of prednisone or equivalent dose of another
corticosteroid preparation for at least 4 weeks prior to the first dose of ALXN1007.
Patients receiving immunosuppressive medications (including but not limited to
methotrexate, hydroxychloroquine, azathioprine, cyclosporine and mycophenolate mofetil)
must be on a stable dose for at least 4 weeks prior to the first dose of ALXN1007.
Patients receiving oral anticoagulants or antiplatelet agents (including but not limited
to aspirin) must be on stable doses for at least 4 weeks prior to first dose of ALXN1007.

Patients must be willing and able to give written informed consent and to comply with all
study visits and procedures.

Exclusion Criteria:

Patients meeting the ACR classification criteria for systemic lupus erythematosus,
systemic sclerosis or other systemic autoimmune diseases other than Primary APS.

Patients experiencing an acute thrombosis or a Major Adverse Vascular Event (MAVE) within
12 weeks prior to first administration of ALXN1007.

Patients with skin ulcers from causes other than aPL or who are positive for DVT or venous
insufficiency at Screening. Patients with renal function status requiring chronic dialysis
(defined as dialysis on a regular basis as renal replacement therapy). Patients with
unresolved meningococcal disease or with known active bacterial, viral, fungal,
mycobacterial or other infection. Patients that have received IVIg treatment within 4
weeks prior to first dose of ALXN1007. Patients that have received a course of rituximab
(RITUXAN®) therapy within 12 months prior to first dose of ALXN1007 or have evidence of
persistent depletion of the targeted lymphocyte population. Women who are pregnant or
nursing.