US regulators have approved thalidomlde, the drug which was banned for causing birth defects. The drug will be tested for cancer treatment. Celgenc, a New Jersey-based company, has been permitted to test Thslomid, the company's version of thabdomide, against multiple myeloma, the most common form of bone marrow cancer. The company can conduct clinical trials but will not be allowed to market the drug, The US food and drug administration (FDA) has also given the treatment an'orphan drug' status. Orphan status is intended to encourage research and development into new therapies for diseases that affect nearly 200,000 US patients a year. Because the market for such drugs is small, manufacturers are given exclusive rights to market the drug for seven years after they get the approval.