Objectives: Clinically meaningful treatment of EBS requires significant and sustainable reduction of blister formation. Currently, there is no treatment for this rare condition.
Materials & Methods: We conducted a randomized, controlled, Phase 2/3 trial of topical application of 1% diacerein cream in 17 EBS patients. A 4-week intervention phase (primary end point: reduction in blister numbers >40%) and a 3-month follow-up were conducted in 2 sequential years, with a cross-over of groups after year 1. Reaching initial blister numbers (+/-10%) was a secondary end point. Pharmacokinetic analysis of rhein was performed in 2 patients.
Results: 60% of discerein patients and 15% of placebo patients had a reduction in blister numbers >40% after 4 weeks of intervention. At the 3-month follow-up, 12.5% of diacerein patients and 67% of placebo patients reached baseline blister numbers. The highest level of rhein in urine and serum was 39.9 ng/mL and 20.1 ng/mL, respectively, which is at least 100 times lower than the level after oral adminstration. No adverse effects were observed.
Conclusions: This trial provides evidence that the orphan drug diacerein 1% cream is highly efficacious and may provide a sustainable long-term effect on blister formation in EBS patients.