Sept 11 (Reuters) - Novacea Inc said it will not develop its cancer drug Asentar even after U.S. health regulators released the clinical hold on it, sending the biopharmaceutical company’s shares to a lifetime low. The company, which agreed to be acquired by privately held Transcept Pharmaceuticals Inc earlier this month, had terminated the late-stage study of Asentar in November 2007 due to an unexplained imbalance of deaths between the treatment and control arms of the trial.