Immune tolerance with rituximab in congenital haemophilia with inhibitors: a systematic literature review based on individual patients' analysis.

Rituximab, a monoclonal antibody against the pan B-cell antigen CD20, has been successfully used in both adults and children for the management of malignant and non-malignant immune-mediated disorders including acquired haemophilia. On the basis of this positive experience, a number of investigators have recently used this agent in patients with congenital haemophilia and inhibitors refractory to first-line treatments. After a careful electronic and hand search, we have collected 29 studies that included 49 cases. A durable complete remission was obtained in 53% of the cases and no severe adverse events related to rituximab were recorded. A multivariate analysis applied to individual patients' data identified the diagnosis of a mild/moderate haemophilia and the concomitant treatment with factor VIII concentrates and immunosuppression agents as covariates associated with an increased response to rituximab. Large prospective randomized studies with an adequate follow-up are needed to confirm these preliminary findings.