ABSTRACT
In November 2018, the U.S. food and drug administration (FDA) issued guidance for the development of drugs for chronic hepatitis B virus infection (draft for comments) (hereinafter referred to as draft for comments), and in April 2022, the FDA issued Chronic Hepatitis B Virus Infection: Developing Drugs for Treatment, which has been updated with some details based on the Draft for Comments. This guidance further emphasizes the importance of HBsAg clearance in clinical trials, and classifies chronic suppressive therapy into two categories, namely noninferiority (NI) (or superiority) test with nucleos(t)ide analogues as control and add-on superiority trial with nucleos(t)ide analogues as control, and as for the latter, HBV DNA is no longer recommended as a primary endpoint of the trial, which poses a huge challenge to the development of innovative drugs targeting HBV DNA. The new finite duration therapy should aim to eliminate HBsAg and reduce virologic relapse and the risk of liver disease progression during treatment cessation. Reduction in HBsAg from baseline is not recommended as a primary endpoint for phase Ⅲ clinical trials, since the correlation between such reduction and clinical response remains unclear. In addition, this guidance also specifies the duration of treatment cessation and treatment consolidation period and the criteria for withdrawal of nucleos(t)ide analogues.
ABSTRACT
Objective To observe the ER ultrastructures in humn embryonic epithelial cells of colonic mucosa、renal tubule and hepatocytes and also their alterations in embryogenesis.Methods Transmission electromicroscopy technique.Results With the embryonic development, the ER increased in amount, became complex in structure and with its characteristic ER structures in different cells. Conclusion The changes of ER structures are one of the characters during cell differentiation.