Prothena rockets up with early data on a Roche-partnered Parkinson's drug

In a small study, an early-stage Parkinson's treatment from partners Prothena ($PRTA) and Roche ($RHHBY) reduced levels of a protein with ties to the memory-destroying disease, sending the former company's shares up about 40%.

Prothena's antibody, PRX002, demonstrated itself safe in a dose-escalating Phase I study on 40 healthy patients, meeting its primary goal, the company said. On top of that, the treatment managed to reduce serum levels of alpha-synuclein, according to Prothena, cutting down on a protein many scientists believe plays a role in the development and progression of Parkinson's disease. The biotech didn't disclose detailed efficacy results from the study but said PRX002 slashed mean alpha-synuclein by as much as 96% after a single dose, a free-of-context data point the company believes bodes well for its ongoing Phase I study on patients with Parkinson's.

Investors ate up the news, bidding up Prothena shares to $41 in after-hours trading. And although such a reaction to Phase I results from healthy volunteers seems a bit hasty, the company insists that it has turned a corner with the alpha-synuclein hypothesis. Demonstrating PRX002's safety in humans "may translate into a clinically meaningful delay or reversal of disease progression in patients with Parkinson's disease," Chief Scientific Officer Gene Kinney said in a statement, and the company is looking forward to posting more efficacy data next year.

Roche bought into PRX002's promise in late 2013, handing over an undisclosed upfront payment and up to $600 million tied to clinical and commercial milestones. In exchange, Roche gets the lion's share of a 70-30 split of the drug's costs and profits in the U.S., taking full responsibility for its future around the globe with its partner in line for royalties. Prothena has banked $45 million from the deal to date, the company said.

Beyond PRX002, Prothena is working through a Phase III trial with its lead candidate, NEOD001 for the rare AL amyloidosis, and preclinical work on the psoriasis treatment PRX003. The biotech spun out of Elan ($ELN) back in 2012 with a handful of monoclonal antibodies and a $125 million purse to make something of them.

- read the results