Drug repurposing in Raynaud's phenomenon through adverse event signature matching in the World Health Organization pharmacovigilance database

Aims Several pharmacological treatments are recommended for Raynaud's phenomenon (RP) secondary to systemic sclerosis, but they only have modest efficacy. A way to efficiently identify new drugs is drug repurposing, which can be based on signature matching. The signature could be derived from chemical structures, pharmacological affinity or adverse event profiles. We propose to use the World Health Organization (WHO) pharmacovigilance database to generate repositioning hypotheses for treatments of RP through adverse event signature matching. Methods We first screened all drugs associated with at least 1 case of erythromelalgia, an adverse effect opposite to RP. In parallel, to define the adverse event signature of drugs recommended in secondary RP from the WHO pharmacovigilance database, we selected the 14 most representative adverse drug reactions (ADRs). Lastly, we performed a hierarchical cluster analysis to identify drugs with similar ADR signature to vasodilatory drugs used in RP. Results In total, 179 drugs were associated with erythromelalgia; they were related to 860 334 adverse events representative of RP drugs in the WHO pharmacovigilance database. Hierarchical cluster analysis allowed identification of 6 clusters. The most stable cluster contained 7 drugs, among which 5 are recommended in secondary RP, or pertain to the same drug class: epoprostenol, nifedipine, nicardipine, lacidipine and israpidine. The 2 remaining drugs were alemtuzumab and fumaric acid. Conclusion Our ADR signature matching approach suggests that alemtuzumab and fumaric acid could be effective treatments of secondary RP. The latter is currently being investigated as a treatment of pulmonary hypertension in systemic sclerosis.