failure of recruit

The aim of the investigators' study is to evaluate whether monitoring serum rituximab levels could be an interesting tool in the follow-up of ANCA-associated vasculitis patients.

All consecutive patients, hospitalized for a new diagnosis of ANCA-associated vasculitis or the relapse of a known ANCA-associated vasculitis, in which the decision to start an induction regimen with rituximab has been taken, will be included.

Serum rituximab levels (along with serum anti-rituximab antibodies levels) will be determined (at M+1 and M+3) and the correlation with clinical outcome at M+6 will be analyzed.

Inclusion Criteria:

• Age > 18 years
• Granulomatosis with polyangiitis or microscopic polyangiitis (according to Chapel Hill criterions), with or without detectable ANCA
• Decision taken to start an induction regimen with rituximab
• Informed and having signed the study consent form
• If of child-bearing potential, female patients will have use an effective method of contraception during RTX (rituximab) treatment and in the 12 months following RTX treatment stop
• no-breast-feeding during RTX treatment and in the 12 months following RTX treatment stop

Exclusion Criteria:

• Other primary or secondary systemic vasculitis
• Incapacity or refusal to sign the informed consent form
• Incapacity or refusal to adhere to treatment or perform the follow-up examinations required by the study
• Allergy, documented hypersensitivity or contraindication to the medications used in the present study (corticosteroids, rituximab)
• severe active infection
• Patient with severe heart failure (stage NYHA IV) or any other unstable heart disease Pregnancy, except for cases where the expected benefit oj treatment seems to surpass the potential risks
• Patients with active hepatitis B
• Any live vaccine within four weeks prior to the first infusion of RTX

Granulomatosis with polyangiitis or microscopic polyangiitis (according to Chapel Hill criterions), with or without detectable ANCA