In October 2009, Prosensa partnered with GSK for the development of its lead compound PRO051. Both parties are working closely together to make this drug available to patients.
Prosensa’s lead compound PRO051/GSK2402968 is highly sequence-specific, i.e. no 100% full length hits elsewhere in the human genome, reducing the risk for off-target effects. PRO051/GSK2402968 thus specifically induces exon 51 skipping in the DMD gene, which, given the frequencies in various international DMD mutation databases, could in principle correct the reading frame in ~13% of all DMD patients, including patients with deletions of exon 50, exon 52, exons 45-50, exons 48-50, and exons 49-50.
In vitro studies in series of cultured patient cells affected by different relevant deletions demonstrated that PRO051/GSK2402968 induces exon 51 skipping independent of the type of mutation. It was also successfully tested in the hDMD mouse model expressing full length human dystrophin. Clinical proof of concept was obtained in four DMD patients receiving a single intramuscular 0.8 mg dose of PRO051/GSK2402968 [van Deutekom et al., 2007]. In this study PRO051/GSK2402968 was safe, well-tolerated, and effective in specifically inducing exon 51 skipping and dystrophin restoration (up to 35% of normal) in the majority of muscle fibers (up to 94%) in the treated area.
In a subsequent Phase I/II dose-ranging safety study, PRO051/GSK2402968 was administered subcutaneously during 5 weeks in 12 patients at two European clinical centers. The study demonstrated that PRO051/GSK2402968 was well tolerated in all patients and that novel dystrophin expression was detected in each treated patient.
An extension study is ongoing in all 12 patients in order to collect longer term safety data before enrolling patients for a large international multi-center pivotal study in 2010. Prosensa is also preparing for a safety and PK study in non-ambulatory DMD boys. Prosensa has partnered with GSK for the further clinical development of PRO051/GSK2402968.
PRO051/GSK2402968 has obtained an orphan drug designation in the EU and the US.
Glad to see the numbers increasing on their nice site. I had seen 53 a few times (which is what my son needs). This is good news as they are now in the preclinical trial phase (I think they have been for awhile, but like to see it in print). I haven't seen the answer on here, but, for a child to get treatment, will they need a muscle biopsy prior to treatment. Kelvin is still questionable whether he is DMD or BMD, so, I was curious as to how they would determine treatment, when exon 53 skipping makes it here (hopefully). There are some boys with Kelvin's deletions of 45-52 that are considered DMD/BMD. They say for now that Kelvin is DMD, until we watch him and see. He's never had a biopsy. Michelle