Abstract: Early phase trials refer to the early exploratory stage of transferring drug development into clinical trials. With China's strong encouragement for innovative drug research and development and enterprises vigorous investment, a large number of innovative drugs have entered early clinical trials. Early phase trials are generally based on innovative diagnosis and treatment mechanisms, pharmaceutical technology and drug delivery methods. Their research design are complex and diverse, and the new technology such as computer simulation are also widely used in the early phase trial process. These aspects are major challenges for the scientific and ethical review of early phase trials. Based on the characteristics of early phase trials, this article analyzes the ethical issues in early clinical trials such as risk uncertainty, therapeutic misunderstanding, subject compensation, breakthrough treatment, etc., and puts forward ethical countermeasures and suggestions.

Key words: early clinical trials,  ethical challenges, countermeasures