Vivus (NASDAQ: [[ticker:VVUS]]), the Mountain View, CA-based obesity drug developer, failed to win FDA clearance to start selling its combination drug in the U.S. The agency, in a complete response letter to the company, requested a “comprehensive assessment” on whether the Vivus therapy, a combination of phentermine and topiramate (Qnexa), is linked to birth defects or miscarriages. The company said it plans to respond to the FDA’s questions in writing in about six weeks. The rejection is no big surprise, given that an FDA advisory panel in July recommended the application be turned down, and the FDA this month rejected the application of another obesity drugmaker, San Diego-based Arena Pharmaceuticals (NASDAQ: [[ticker:ARNA]]).