The Body Covers: The 66th Annual Scientific Meeting of the American College of Gastroenterology
What's New in Gastrointestinal Pharmacology
October 19, 2001
The pegylated interferons have been formulated to be absorbed slowly by the body and to provide higher sustained blood levels of the medication. Injections can be administered once weekly as opposed to three times weekly with the standard interferons. Two companies have pegylated interferon and have performed extensive testing in the U.S. and abroad. Pegylated interferon alfa-2-b (Schering Plough) in combination with ribavirin when taken for 48 weeks results in 54% sustained viral response rate or SVR, which means that six months after treatment has been stopped no trace of the virus can be found in the blood when tested by very sensitive molecular assays. Pegylated interferon alfa-2-a (Hoffman La Roche) in combination with ribavirin when take for 48 weeks results in 56% sustained viral response rate. Side effects and tolerability are similar. If patients adhere to both of the medications and are able to take 80% of the doses at least 80% of the prescribed time results can be even better. Some patients will require that the medications be cut back due to side effects. Pegylated interferon alfa-2-b plus ribavirin is approved for use in the U.S. while pegylated interferon alfa-2-a plus ribavirin is awaiting approval by the FDA. These new therapies have now become the standard of care and over the next year we will undoubtedly see greater use and better results.
Newer therapies and strategies are now being tested or planned. One very exciting type of medication consists of inhibitors of enzymes that the hepatitis C virus uses for replication. In a way very similar to how the HIV virus can be blocked, hepatitis C can be blocked by protease, helicase or polymerase inhibitors. These agents may be effective by themselves or in combination (as in the treatment of HIV), or they could be added to interferon. These enzyme inhibitors are being designed and are still not in the human testing stage. Another exciting new treatment is the therapeutic vaccine. This treatment enhances the infected patient's own immune response to the hepatitis C virus so that the body may finally rid itself of the infection. Again, work in this field is still in the very early stages. Other new approaches use molecular tools in order to render the virus ineffective. These are called "hammerhead ribozymes" or "anti-sense oligonucleotides." The way these agents work is to break the viral RNA (hammerhead ribozymes) in several spots and thus render it useless or to incorporate bits of RNA (anti-sense oligonucleotides) into the viral RNA, again rendering it useless. Early trials of ribozymes are underway, but there is no data available as of yet.
A totally new treatment looks at the possibility of slowing down the body's ability to lay down scar tissue in the liver. This is a different approach than previous ones that have aimed at getting rid of the virus. With medications such as gamma interferon and interleukin-10, preliminary data shows that the amount of scar tissue can be reduced even if the virus remains present. This will hopefully offer help to patients with more advanced degrees of fibrosis or cirrhosis. Large clinical trials are now getting underway.
In summary, better treatment alternatives using pegylated interferons in combination with ribavirin are now available and have become the new standard of care. Other therapeutic advances are being developed but will not likely be available outside of clinical trials for several years. For patients who need treatment, it is recommended that they get treated now.
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