US regulators have approved thalidomide, the much maligned drug banned for causing birth defects, for testing as a cancer treatment. New Jersey-based Celgene has been cleared to test Thalomid, the company's version of thalidomide, against multiple myeloma, the most common form of bone marrow cancer. The company can conduct clinical trials but may not yet market the drug. The US Food and Drug Administration (FDA) has also given the treatment 'orphan drug' status. Orphan status is intended to encourage research and development into new therapies for diseases that affect less than 200,000 US patients a year.