Development of monoclonal gammopathy under biotherapy in psoriasis: a French multicenter retrospective study.

Background: Biotherapies or targeted therapies are fairly new treatments indicated for moderate to severe psoriasis. The side effects appear to be mainly infectious or cancerous. The role of biotherapies in the development of a pre-cancerous condition, monoclonal gammopathy of undetermined significance (MGUS), has recently been debated in the literature.

Objectives: To evaluate the incidence of MGUS in psoriasis patients treated with biotherapy.

Materials And Methods: This study was a French multicenter retrospective study carried out through the French multicenter study group RESOPSO. Data on the results of serum protein electrophoreses performed before and within at least six months after the start of the biotherapy were collected. Demographic data, medical history, and psoriasis treatment history were specified.

Results: Four hundred and forty three patients were eligible for inclusion. Of these, three presented with monoclonal gammopathy for which the assessment was in favor of MGUS. The average treatment period was 19.7 months. Six patients presented with MGUS prior to the treatment. These patients' immunoglobulin levels remained stable, with an average remission of 24 months. Only psoriatic rheumatism appeared to be statistically linked to MGUS.

Conclusion: The incidence and frequency of MGUS in psoriasis patients treated with biotherapy do not appear to increase relative to the general population.