Drug3rd line3 diseases

Rituximab

Anti-CD20 monoclonal antibody; depletes B cells

Response rate
Promising in refractory cases
Onset
Weeks–months
Route
IV 375 mg/m² x4 or 1000 mg x2
Line
3rd
IgM effect
Reduces anti-C1q antibody production via B-cell depletion
Evidence level
amber

Used across diseases

DiseaseResponse rateLineEvidence
Hypocomplementemic Urticarial Vasculitis SyndromePromising in refractory cases3rdamber
Schnitzler SyndromeIneffective on inflammationNot recommendedred
Waldenström's Macroglobulinemia~25-40% (monotherapy); higher in combinations1stamber

Evidence summary

B-cell depletion with rituximab reduces anti-C1q autoantibody production. Shown effective in refractory HUVS, especially with renal involvement. Long-term follow-up of pediatric DNASE1L3-mutant siblings showed rituximab was the most effective treatment. Emerging as a key option for severe/refractory disease.

Approved indications

Conditions for which Rituximab has regulatory approval (not specific to rare diseases covered here):

ANCA-Associated VasculitisRheumatoid ArthritisNon-Hodgkin LymphomaCLL

Drug identifiers

DrugBankDB00073
ATC CodeL01FA01

Sources (2)

DetailsÖzen Taş et al. (2025) Treatment and long-term follow-up of pediatric patients with hypocomplementemic urticarial vasculitis syndrome (HUVS): a case-based reviewDOI
DetailsHamid R et al. (2019) Treatment of urticarial vasculitis: A systematic reviewDOI