Oxford BioMedica’s novel gene therapy for Parkinson’s disease is continuing to show promise in mid-stage clinical development, after patients taking part in a Phase I/II trial of the drug maintained an improvement in motor function after one year of therapy.

One of the company’s flagship candidates, ProSavin is administered directly into the brain to deliver three genes that transform certain cells into ones able to produce the neurotransmitter dopamine. Parkinson’s disease is characterised by the degeneration of cells that produce dopamine, and so the drug is designed to replenish stock in patients with the illness and thereby reverse some of the associated symptoms.

So far, ProSavin has performed well in clinical testing and latest results of the ongoing dose-escalation Phase I/II trial are also encouraging. Aside from indicating that the drug is safe and well-tolerated in patients with mid-to-late forms of PD, the findings also show that patients who received the first, lowest dose have maintained improvements (of an average 29%) for one year, and that those given a second, higher dose have achieved similar benefits at three months.

The firm has been given the support of an independent data monitoring committee to advance the trial and administer not only a third dose of the ProSavin, but one that is delivered via a new technology designed to cut the required surgery time by 50% and facilitate higher dosing, and therefore, according to Oxford BioMedica, expand the product’s market opportunity. Consequently, the group is currently putting together a protocol amendment for this new technology, which it plans to submit to French regulators before the end of the third quarter, it said.

Commenting on the drug’s progress, John Dawson, Oxford BioMedica’s Chief Executive Officer, said the company is “delighted by the safety and efficacy data of emerging from this first-in-man study of ProSavin”, and added that protocols are already being designed for the next stage of development which will be presented to regulators on both sides of the Atlantic.

Partnering soon?
Furthermore, he said “discussions with prospective partners are also progressing well”, and that it is hoped the current study will be completed by the second half of next year so that the therapy can be tested in larger studies with the aid of a partner “as soon as possible”.

Oxford BioMedica will be pinning much of its hopes on ProSavin, particularly in the wake of a major setback regarding another key product in its portfolio – the cancer vaccine TroVax – which has substantially delayed its development. According to the firm, Parkinson's disease affects approximately 4.1 million people around the globe, and even though none of the current treatments provide long-term relief from symptoms, by 2012, sales could overshoot $4.6 billion in the major developed countries.