NOVATO -- BioMarin Pharmaceutical Inc. (Nasdaq: BMRN) today announced the start of phase 3 trial in Europe of a treatment for a rare immune system disease, Lambert-Eaton Myasthenic Syndrome, or LEMS.

The first patient in the trial has been dosed with the drug, amifampridine phosphate, according to the company. The disease mainly causes muscle weakness. The treatment received marketing approval in the European Union in January 2010.

"In early 2010, we introduced the first approved therapeutic option to the EU to treat LEMS, a rare, serious and debilitating disease," said Jean-Jacques Bienaime, chief executive officer of BioMarin.  "We are conducting this phase 3 trial to meet the regulatory requirements of the FDA in order to gain marketing authorization in the U.S., and are evaluating different commercialization options in the meantime. This marks the fourth clinical trial initiated in 2011 as we remain committed to the advancement of our pipeline over the next few years."

A phase 3 trial is a double-blind, placebo-controlled randomized discontinuation study followed by an open-label extension period in approximately 30 patients across 25 sites worldwide. The purpose of the study is to evaluate the efficacy and safety, including the long-term safety.

With a half-hour left in Tuesday's trading session, the per-share price of BioMarin's stock was $27.45, an increase of 22 cents or nearly 1 percent from Monday.