Prosensa’s technology involved exon skipping, a novel and patented technique that altered the way in which the gene was expressed to make a shorter protein, which was still functional. The technique involved the use of an oligonucleotide.

We had concerns about delivery but the initial target disease had a few features that made us more optimistic. Firstly, the target tissue was muscle and it turned out that in the case of Duchenne’s, the muscle cells were leaky and allowed the entry of the oligo more readily than would normally be the case. In addition because the protein had a low turnover and the oligonucleotide is stable, only a small dose of the drug would need to be delivered. This addressed our main concerns with this approach, which were dosing and delivery.

The clinical trials process was not totally straight forward. This is a disease that can take three years or more for the parents to identify so reversing it may also take time. Indeed it became evident as more data was acquired that the longer the treatment went on the more positive the effect on the patient, so long as the disease was treated early enough.

Prosensa’s technology came out of the lab of Professor Gert-Jan van Ommen at the University of Leiden and the co-founder Gerard Plattenburgh was the founding CEO, who had significant scientific knowledge as well as previous experience in a biotech company, Genpharm International, one of our previous investments. The management was strengthened with local and international talent and over time Hans Schikan, ex-Genzyme, took on the CEO slot bringing orphan drug expertise to Prosensa. Hans then took the company public in 2013. In 2015 the company was acquired by BioMarin who brought further knowledge of the orphan drug space as well as significant expertise in regulatory matters. Based on their up front payment they are clearly confident that they can obtain FDA and EU approval.

Abingworth role

Abingworth co-led the $18 million Series A financing in December 2006. Stephen Bunting was a board member and Chairman of the Remuneration Committee. Abingworth was actively involved in recruitment of the senior management team. We introduced Peter Goodfellow to Prosensa, who was taken on as an independent board member and was very active in helping with scientific strategy. Abingworth also assisted with the IPO.

BusinessOrphan drug development using exon skipping
IndicationInitial focus on Duchenne’s Muscular Dystrophy
StageCompleted pivotal trials. Seeking approval in the EU and US
Initial InvestmentDecember 2006
OutcomeAcquired by BioMarin for up to $840 million: $680 million up front and a further $160 million conditional on approval in the EU and US