Prothena (PRTA) soars on study results for Parkinson's disease drug

NEW YORK (AP) -- Shares of Irish drug developer Prothena surged Friday after the company reported promising results from an early-stage study of a drug designed to treat Parkinson's disease.

Prothena said the study showed the drug, PRX002, was safe, without serious side effects, and that it reduced levels of a protein that is believed it be associated with the disease. The drug was tested on 40 healthy people, which is common in early clinical trials of experimental drugs. Prothena is conducting studies that will involve more people, including patients who suffer from the disease.

Prothena stock was up $8.26, or 28 percent, to $37.49 in afternoon trading. It hit $45 earlier in the day.

PRX002 is designed to reduce levels of free serum alpha-synuclein. When that protein builds up in the brain, it is associated with Parkinson's disease and related conditions.

Wedbush analyst Heather Behanna said the study is an important first step for Prothena, but it's not clear if the drug will work on humans the same way it has worked in preclinical models. Behanna rates Prothena shares "Outperform" with a price target of $46.

Dublin-based Prothena Corp. announced a development deal with Roche in December 2013. The company says it could get as much as $600 million in milestone payments from Roche, as well as a portion of profits and royalty payments on sales of the drug if it is approved. Prothena has received $45 million so far.