A Study of Intravenous MabThera/Rituxan in Pediatric Patients With Severe Granulomatosis With Polyangiitis (Wegener's) or Microscopic Polyangiitis

Inclusion Criteria:

• Age at screening between >/= 2 and < 18 years
• Diagnosis of granulomatosis with polyangiitis (EULAR/PRINTO/PRES 2008, Ankara criteria for childhood Wegener's granulomatosis) or diagnosis of microscopic polyangiitis (according to the Chapel Hill Consensus Conference)
• Newly diagnosed patients or patients with relapsing disease according to the following definition:

The recurrence or new onset of potentially organ- or life-threatening disease (i.e. one or more major BVAS/WG items as listed in the protocol or disease severe enough to require treatment with cyclophosphamide)

• For patients of reproductive potential (males and females), use of reliable means of contraception throughout the study participation
• For all eligible patients, mandatory prophylactic treatment for Pneumocystis jirovecii infection

Exclusion Criteria:

• Diagnosis of Churg-Strauss syndrome, as defined by the Chapel Hill consensus Conference (Jennette 1994)
• Limited disease that would not normally be treated with cyclophosphamide
• Severe disease requiring mechanical ventilation due to alveolar hemorrhage
• Requirement for plasmapheresis or dialysis at screening
• Pregnancy or breastfeeding
• Evidence of other significant uncontrolled concomitant disease, or of disorder or condition that, in the investigator's opinion, would preclude or interfere with patient participation
• Primary or secondary immunodeficiency (history of or currently active), including known history of human immunodeficiency virus (HIV) infection
• Known active infection of any kind (excluding fungal infections of nail beds), or any major episode of infection requiring hospitalization with IV anti-infective agents within 4 weeks of baseline or completion of oral anti-infective agents within 2 weeks prior to baseline
• History of deep space/tissue infection within 24 weeks prior to baseline
• History of serious recurrent or chronic infection
• History of cancer (except for basal cell and squamous cell carcinoma of the skin that have been excised and cured)
• Currently active alcohol or drug abuse or history of alcohol or drug abuse
• History of severe allergic or anaphylactic reaction to a biologic agent or known hypersensitivity to any component of rituximab or to murine proteins
• Previous treatment with rituximab
• Previous treatment with any cell-depleting therapies
• Receipt of oral or IV cyclophosphamide within the previous 4 months prior to the baseline visit
• Receipt of infliximab within 3 months, adalimumab within 2 months or etanercept within 1 month prior to the baseline visit
• Treatment with any investigational agent within 28 days of baseline or 5 half-lives of the investigational drug (whichever is longer)