GSK Puts Down $25M for Prosensa’s Mid-Stage Candidate for Duchenne Muscular Dystrophy

GlaxoSmithKline (GSK) is paying £16 million (about $25.33 million) for rights to Prosensa’s Phase II Duchenne muscular dystrophy (DMD) drug and options to three more DMD candidates. Prosensa is eligible to up to £412 million (approximately $652.23 million) in milestones if all four compounds are successfully developed.

The four RNA-based products included under this deal are intended to treat specific but different subpopulations of patients. GSK has obtained an exclusive, worldwide license to develop and commercialize Prosensa’s lead molecule, PRO051. The candidate is intended to treat DMD by targeting the skipping of exon 51 of the dystrophin gene, mutations of which result in the absence of normal dystrophin protein, which is necessary for proper muscle cell function.

GSK’s Neurosciences Medicines Development Centre will fund further development activities with regard to PRO051 and will work in collaboration with Prosensa. Both parties have begun preparations for a Phase III study, planned to start early next year.

In addition, GSK has exclusive options to license three more RNA-based compounds targeting additional DMD exons. One such option includes Prosensa’s second lead compound, PRO044, which targets the skipping of exon 44. Prosensa expects to initiate a Phase I/II study before the end of this year. In this case, GSK’s option rights will be triggered by a successful completion of this study.

Prosensa is entitled to double-digit royalties on all product sales. The company retains commercial participatory rights and has an option to expand its commercial rights in certain European countries.