BioMarin Pharmaceutical has achieved orphan drug designation from the US Food and Drug Administration (FDA) for 3,4-diaminopyridine (3,4-DAP), amifampridine phosphate, a new treatment for the rare autoimmune disease Lambert Eaton Myasthenic Syndrome (LEMS).

The company also received orphan drug designation for the treatment in the EU in October 2009, which if approved would make it the first approved treatment for LEMS in Europe, conferring orphan drug protection and providing ten years of market exclusivity in Europe.

BioMarin CEO Jean-Jacques Bienaime said that amifampridine phosphate for LEMS is an exciting treatment for a serious and debilitating autoimmune disease.

“We look forward to meeting with the FDA in early 2010 to determine the necessary regulatory path and we are also preparing to launch the product in Europe in the first quarter of 2010,” Bienaime said.

LEMS is a rare autoimmune disease characterised by muscle weakness caused by autoantibodies to voltage gated calcium channels, leading to a reduction in the amount of acetylcholine released from nerve terminals.

Around 2,000–5,000 patients are believed to have the disease in the EU and 1,200–3,100 patients in the US. Approximately 50% of LEMS patients diagnosed have small-cell lung cancer.