Cheshire-based Alexion Pharmaceuticals said it expects within months to start selling its Soliris drug in Europe after regulators there gave it a “positive opinion” – one of the final steps before marketing rights are granted by the European Commission. Soliris, a so-called orphan drug, can be use to treat a rare disease known as paroxysmal nocturnal hemoglobinuria, or PNH, which destroys patients’ red blood cells, and can cause anemia, kidney disease and death. There is currently no treatment for the disease in Europe.