For various reasons, most drug candidates cannot successfully pass the drug approval process. Therefore, the development of reliable methods for predicting clinical trial outcomes of drug candidates is crucial in improving drug development. In this study, we propose an ensemble classifier based on a weighted least squares support vector regression (LS-SVR) for predicting successes and failures of clinical trials. The efficacy of the proposed ensemble classifier is demonstrated through an experimental study on the PrOCTOR dataset, which consists of informative chemical and target-based features of drugs. Upon comparison with other models, the proposed ensemble classifier obtained the highest area under the receiver operator curve (AUC). These results demonstrate that our classifier can be used to effectively predict the outcomes of clinical trials.