Prothena Surges On Positive Phase I Results Of Parkinson's Drug PRX002

(RTTNews) - Prothena Corp plc (PRTA), a late-stage clinical biotechnology company, on Thursday said a Phase I study of PRX002, its experimental Parkinson's disease drug, met its primary objective of safety and tolearability.

Following the announcement, Prothena shares jumped more than 38% to $40.50 in after-hours trade on the Nasdaq.

PRX002 is a monoclonal antibody for the potential treatment of Parkinson's disease and other related synucleinopathies. The drug is the focus of a worldwide collaboration between Prothena and Roche.

In the Phase 1 single ascending dose study of PRX002, the drug was safe and well-tolerated.

Further, results from the study showed that administration of PRX002 leads to mean reduction of free serum alpha-synuclein levels of up to 96%.

These overall results were highly statistically significant.

Reduction of free serum alpha-synuclein, a protein potentially involved in the onset and progression of Parkinson's disease and the target of PRX002, was shown to be robust, rapid and dose-dependent after just a single dose.

The Phase 1 double-blind, placebo-controlled, single ascending dose study enrolled 40 healthy volunteers.

No hypersensitivity reactions or drug-related serious adverse events were reported. PRX002 demonstrated favorable pharmacokinetic properties, supporting the current dosing frequency in the on-going Phase 1 multiple ascending dose study in patients with Parkinson's disease.

here were no treatment emergent adverse events (TEAEs) in greater than 10% of subjects. The only TEAEs in greater than 5% of subjects were vessel puncture site pain, headache and viral infection. All PRX002-related adverse events were mild and no dose limiting toxicities were observed.

In December 2013, Prothena and Roche entered into a worldwide collaboration to develop and commercialize antibodies that target alpha-synuclein, including PRX002.

To date, Prothena has received $45 million of the potential $600 million in total milestones through its collaboration with Roche.

Prothena has an option to co-promote PRX002 in the U.S., where the companies share all profits, as well as development and commercialization costs, on a 30/70 basis (30% Prothena and 70% Roche).

Outside the U.S., Roche will have sole responsibility for developing and commercializing PRX002 and will pay Prothena up to double-digit royalties on net sales.

Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease. Parkinson's affects one in 100 people over age 60, and there are an estimated seven to ten million patients living with Parkinson's disease worldwide.

The motor symptoms of Parkinson's disease result from the death of dopamine-generating cells in the substantia nigra, a region of the midbrain. Early in the course of the disease, the most obvious symptoms are movement-related; these include shaking, rigidity, slowness of movement and difficulty with walking and gait. Later, thinking and behavioral problems may arise, as well as depression and sleep problems.

Current treatments for Parkinson's disease are only effective at managing the early motor symptoms of the disease, mainly through the use of levodopa and dopamine agonists.