- Shares of Arrowhead Research stock were up 34% in premarket trading Thursday to $9.05 before falling back down a bit by the end of the day, driven by promising early results from a hep B drug trial.
- Gilead is also at work developing an antiviral treatment for hepatitis B.
- Jefferies analysts are projecting that Arrowhead's hep B treatment, ARC-520, could potentially reach $4.5 billion in annual sales by 2020 if approved.
Approximately 240 million people worldwide carry the hepatitis B virus (HBV), with roughly 600,000 HBV-related deaths occuring each year. In the U.S. alone, it is estimated that 2.2 million people are carriers—and 2/3 of those individuals are foreign born.
Prevalence varies between countires. Low-prevalence countries (0.1% to 2%) include the U.S., Canada and Western Europe; intermediate-prevalence countries (3% to 5%) include Japan, the Middle East and Latin America; and high-prevalence (10% to 20%) countries include China, Africa, and some other countries in Asia.
The net effect of infection is the progression of liver disease, starting with hepatitis, progressing to fulminant hepatitis and in worst-case scenarios, liver cancer. Although the market is bullish on Arrowhead's treatment, not everyone is convinced.
Nonetheless, early studies in humans and chimps showed that a single dose of ARC-520 reduced the E-antigen (HBeAg), a biomarker for hepatitis B, by 98%. In addition, treatment also reduced the presence of another biomarker, the S-antigen, by 99% in human patients. Notably, there were no serious side effects or adverse events in either the chimps or humans during the studies.