• The eligibility criteria will be checked at the inclusion/randomization visit. Patients meeting the following criteria may be included in the study:

• Age \> 18 years

• Written inform consent

• Active mixed cryoglobulinemia vasculitis, at initiation of rituximab, define by a. a clinically active vasculitis with skin, joint, renal, peripheral nerve, central neurological, digestive, pulmonary and/or cardiac involvement , b. history of positive cryoglobulinemia and/or positive Rheumatoid factor associated with low C4 complement level , and/or a monoclonal component (IgM Kappa) and/or a histologal proof of vasculitis in the affected organs

• Affiliated to National French social security system

• Having received Rituximab as induction therapy within 6 weeks (1 to 4 infusions, dose at the discretion of the investigator)

• Female subjects of childbearing potential must have a negative serum or urinary pregnancy test at inclusion visit, and confirmed monthly while in study, out to at least 92 days (5 half lives) post last dose.

• For subjects with reproductive potential (male or female), a willingness to use contraceptive measures adequate to prevent the subject or the subject's partner from becoming pregnant during the study from 2 weeks prior to administration of the 1st dose of study agent until 92 days after the last dose of study agent. Therefore the subjects agree to 1 of the following:

‣ Complete abstinence from intercourse from 2 weeks prior to administration of the 1st dose of study agent until 92 days after the last dose of study agent (Sexual inactivity by abstinence must be consistent with the preferred and usual lifestyle of the subject. Periodic abstinence (e.g. calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception) OR

⁃ Consistent and correct use of 1 of the following acceptable methods of birth control for 1 month prior to the start of the study agent, during the study, and 92 days after the last dose of study agent o Oral contraceptive, either combined or progestogen alone o Injectable progestogen o Implants of levonorgestrel or etonogestrel o Estrogenic vaginal ring o Percutaneous contraceptive patches o Intrauterine device (IUD) or intrauterine system (IUS) with \<1% failure rate as stated in the product label

‣ o Male partner sterilization (vasectomy with documentation of azoospermia) prior to the female subject's entry into the study, and this male is the sole partner for that subject. For this definition, documented refers to the outcome of the investigator's/designee's medical examination of the subject or review of the subject's medical history for study eligibility, as obtained via a verbal interview with the subject or from the subject's medical records

∙ Double barrier method: condom and occlusive cap (diaphragm or cervical/vault caps) plus spermicidal agent (foam/gel/film/cream/suppository) These allowed methods of contraception are only effective when used consistently, correctly and in accordance with the product label. The investigator is responsible for ensuring subjects understand how to properly use these methods of contraception.

• HIV negative serology ; negative HBs Ag test and HBc Ab test; HCV negative serology or negative HCV RNA if positive HCV serology within 3 months before inclusion:

• o In case of negative AgHBs and positive HBc Ab test, HBV DNA test must be negative; AND Hepatitis B surveillance should be started (monthly HBsAg and HBV DNA testing for the duration of the study treatment and at least every 12 weeks after treatment is discontinued for the duration of study treatment. In addition, antiviral prophylaxis should be started before the first administration of the study treatment and continued until 12 months after completion of study treatment; HCV negative serology or negative HCV RNA if positive HCV serology within 3 months before inclusion

• neutrophils (ANC) \>1x109/L