NEW YORK (Reuters Health) - In patients with diffuse cutaneous systemic sclerosis (dcSSc), treatment with rituximab depletes B cells in the peripheral circulation and in skin, with few adverse events. On the other hand, results of a 6-month pilot study failed to show any clear beneficial effect on skin disease or other manifestations of the disorder.

“However,” the research team writes in the February issue of Arthritis and Rheumatism, “the safety of the medication and the potential efficacy related to B cell infiltration of other organs such as the lungs suggest that rituximab might be worth further studying for systemic sclerosis-associated pulmonary fibrosis, perhaps in combination with cyclophosphamide.”

In their open-label study, Dr. Robert Lafyatis, at Boston University School of Medicine, and colleagues examined the 6- and 12-month month outcomes for 15 patients with early dcSSc treated with the B cell-depleting agent rituximab, in two intravenous doses of 1000 mg each, administered 2 weeks apart.

Treatment produced no more than modest changes in autoantibody levels. Circulating B cells, which were depleted almost completely in 14 subjects at 3 months, tended to recover to pretreatment levels between 6 and 12 months.

Perivascular B cells present in skin biopsies at baseline were absent in most subjects at 6 months, and the number of myofibroblasts in the deep dermis decreased.

Skin thickness and hardness did not change significantly during follow-up, the report indicates, and the investigators observed no evidence of progressive end-organ damage.

“Several features of the clinical course of these treated patients provide some motivation to consider further evaluation of the efficacy of rituximab,” the investigators conclude, including “a lack of progressive pulmonary or renal disease in a population that is at relatively high risk of these complications.”

Furthermore, Dr. Lafyatis and associates maintain, “If a decrease in myofibroblasts is an early, preclinical indicator of improvement in scleroderma, then these data suggest that B cell depletion may be efficacious for the treatment of systemic sclerosis.”

Arthritis Rheum 2009;60:578-583.