European regulators granted the go-ahead for Roche’s MabThera (rituximab) to treat a rare and potentially deadly autoimmune disease with its first-of-its-kind biologic.

Pemphigus vulgaris (PV) causes large, painful blisters on patients’ skin and in their mucous membranes. MabThera previously won approval as a PV treatment in the U.S. and is now authorized to treat four autoimmune disorders in the U.S. and EU.

The European approval comes after a French, Phase III trial found that nearly 90 percent of PV patients attain two or more months of remission when using MabThera followed by a tapered regimen of corticosteroids pills, compared to just 28 percent of patients given only corticosteroids.

There are about 50,000 PV sufferers in Europe and about three out of every 100,000 individuals suffer from the disease worldwide.