Clinical trials are an indispensable part of the drug development process, bridging the gap between basic research and clinical application. During the development of new drugs, clinical trials are used not only to evaluate the safety and efficacy of the drug but also to explore its dosage, treatment regimens, and potential side effects. This review discusses the various stages of clinical trials, including Phase I (safety assessment), Phase II (preliminary efficacy evaluation), Phase III (large-scale validation), and Phase IV (post-marketing surveillance), highlighting the characteristics of each phase and their interrelationships. Additionally, the paper addresses the major challenges encountered in clinical trials, such as ethical issues, subject recruitment difficulties, diversity and representativeness concerns, and proposes strategies for overcoming these challenges. With the advancement of technology, innovative technologies such as artificial intelligence, big data, and digitalization are gradually transforming clinical trial design and implementation, improving trial efficiency and data quality. The article also looks forward to the future of clinical trials, particularly the impact of emerging therapies such as gene therapy and immunotherapy on trial design, as well as the importance of regulatory reforms and global collaboration. In conclusion, the core role of clinical trials in drug development will continue to drive the progress of innovative drug development and clinical treatment.

翻译：临床试验是药物开发过程中不可或缺的环节，它架起了基础研究与临床应用之间的桥梁。在新药开发过程中，临床试验不仅用于评估药物的安全性和有效性，还用于探索其剂量、治疗方案及潜在副作用。本综述讨论了临床试验的各个阶段，包括I期（安全性评估）、II期（初步疗效评估）、III期（大规模验证）和IV期（上市后监测），重点阐述了各阶段的特点及其相互关系。此外，本文探讨了临床试验中遇到的主要挑战，如伦理问题、受试者招募困难、多样性与代表性担忧，并提出了应对这些挑战的策略。随着技术进步，人工智能、大数据和数字化等创新技术正逐步改变临床试验的设计与实施，提高试验效率和数据质量。文章还展望了临床试验的未来，特别是基因治疗和免疫治疗等新兴疗法对试验设计的影响，以及监管改革和全球协作的重要性。总之，临床试验在药物开发中的核心作用将继续推动创新药物开发和临床治疗的进步。