GST-HG131, a pioneering first-in-class drug for hepatitis B treatment developed by Fujian Grandsun Zhonglin Biotechnology Co., Ltd., a subsidiary of Grandsun, has recently been granted Breakthrough Therapy Designation by the National Medical Products Administration. This marks the second time the company has received such a designation for a hepatitis B treatment, following GST-HG141. As an oral small molecule inhibitor of hepatitis B surface antigen (HBsAg), GST-HG131 has exhibited remarkable clinical promise, with data demonstrating its ability to significantly suppress HBsAg levels. Despite its promising outlook, the development of GST-HG131 continues to grapple with challenges such as extended timelines, substantial investment requirements, and inherent risks, leaving the ultimate approval of the drug uncertain.