The drug was found to be safe and well tolerated. PRX002 was also found to deeply penetrate the central nervous system in all doses tested.
Levels of free serum alpha-synuclein, a protein potentially involved in the onset and progression of Parkinson’s disease and the target of PRX002, were reduced up to 97 percent after a single dose.
“These data represent the first reported assessment of an anti-alpha-synuclein antibody in patients with Parkinson’s disease,” Gene Kinney, PhD, president and CEO of Prothena, said in a press release. “In this study we observed PRX002 penetration in the CNS that exceeded our expectations based on our preclinical experience, and a highly statistically significant reduction of free serum alpha-synuclein.
“These Phase 1b data further support our belief that we can choose doses that target and saturate aggregated pathogenic alpha-synuclein in the brain for a Phase 2 study to further explore the potential of PRX002 as a disease-modifying treatment for Parkinson’s disease. Together with Roche, we expect to initiate a Phase 2 study in 2017,” Kinney added.
The six-month Phase 1b clinical trial (NCT02157714) evaluated the safety, tolerability, properties, and immune system response of multiple ascending doses of PRX002 administered by intravenous infusion once every 28 days in 64 patients with Parkinson’s disease.
There were no major treatment emergent adverse events (TEAEs), and no dose-limiting toxicities were observed. PRX002 was showed to have acceptable pharmacokinetics. Patients were randomly assigned to six escalating dose groups of PRX002 or a placebo.
Results of this trial will be presented in an upcoming medical meeting. Prothena is planning to initiate a Phase 2 clinical trial next year.
“Developing new therapies for complex neurological diseases such as Parkinson’s requires dedicated and disciplined science,” said Todd Sherer, PhD, CEO of The Michael J. Fox Foundation for Parkinson’s Research.
“Targeting alpha-synuclein represents a promising path toward a potentially disease-modifying treatment for Parkinson’s disease, and we are very pleased to see PRX002 advance to the next stage of development.”
PRX002, also known as RG7935, a collaboration between Prothena and Roche, binds to and blocks α-synuclein. In March 2015 Prothena announced that in a Phase 1 trial (an initial trial in humans) PRX002 was safe and well-tolerated. The drug also reduced levels of alpha-synuclein in the blood.