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Is There a Cure for Hepatitis B?
The long and short answer is that there is not yet a cure for hepatitis B. Understanding why requires insight into the virus itself and the challenges cure researchers face.
Hepatitis B is an infectious disease caused by the hepatitis B virus (HBV). While most people exposed to hepatitis B will spontaneously clear the virus (eliminating it from the body) soon after infection, a proportion will go on to develop a chronic (persistent) infection.
Of these, around one in four will develop severe liver complications, including cirrhosis (extensive scarring of the liver) and liver cancer, typically years after the initial infection.3
Efforts to find a cure for hepatitis B have been underway since the virus was first identified by scientists at the National Institutes of Health in 1966.4 It soon became clear, however, that numerous hurdles would need to be overcome before an actual cure could be achieved. Chief among these are:
Poor innate immunity: For reasons that are not entirely clear, HBV is not readily recognized by the immune system during early-stage infection and is poorly eliminated by the body's frontline innate immune response.5
Poor adaptive immunity: Over time, the body's disease-specific adaptive immune response also weakens due to a phenomenon known as T-cell exhaustion. When this occurs, the immune system is less able to recognize and launch an immune assault against the virus.5
Viral reservoirs: In chronically infected people, HBV will embed itself within tissues inside and outside the liver, called viral reservoirs. Within these reservoirs, the virus is largely shielded from immune detection and is difficult to reach with antiviral drugs.6
cccDNA: What differentiates hepatitis B from hepatitis C is the unique structure of its viral DNA, called covalently closed circular DNA (cccDNA). Antiviral drugs have limited effectiveness against this seemingly indestructible "mini-chromosome" that continues to pump out new viruses from infected liver cells.7
How Is Viral Hepatitis Spread?
Overcoming the Hurdles
Despite the challenges in finding a cure, scientists have a greater understanding of how HBV infects, replicates, and persists. By targeting and blocking these mechanisms with either one or a combination of therapies, scientists hope to one day render the virus harmless or eliminate it.
Among some of the leading drug candidates are:
Bepirovirsen: An experimental direct-acting antiviral that may block cccDNA from delivering the genetic code used to build new viruses8
HBsAg monoclonal antibody: An experimental form of immunotherapy used to boost the immune system's ability to recognize and launch a targeted immune attack against HBV9
JNJ-64300535: An experimental therapeutic vaccine that may help activate the adaptive immune response in people with chronic hepatitis B infection10
REP 2139/2165: An experimental antiviral direct-acting antiviral that appears to improve the immune system's ability to control the virus11
RO7049389: An experimental direct-acting antiviral that blocks the assembly of new viruses12
Clinical Trials
Today, there are at least 50 different HBV therapies—including more than 25 experimental direct-acting antivirals—undergoing clinical trials, with more expected to follow.13
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发表于 2022-7-8 14:44
