Novartis says U.S. FDA extends review period for bone marrow drug ZURICH (Reuters) - Swiss drugmaker Novartis AG said on Tuesday the U.S.Food and Drug Administration (FDA) had extended a priority review period by up to three months for a new drug application for the treatment of a type of bone marrow cancer. Novartis submitted its application to the FDA for its LBH589 drug, a treatment for multiple myeloma, in March, and the FDA granted the drug priority review status in May, reducing the standard 12-month review period to eight months. The drug works by blocking a key cancer cell enzyme which causes cell stress and leads to the death of these cells. Reporting by Joshua Franklin; Editing by Sunil Nair