Israel’s XTL is testing a new therapy for hepatitis C.Hepatitis C is a major public health concern. The World Health Organization estimates that 170 million people worldwide are chronic carriers of the hepatitis C virus, with 4 million carriers in the United States alone. Hepatitis C is a “stealth killer,” since a person infected with the hepatitis C virus will not link the flu-like symptoms to the virus and will continue with his or her daily routine. The virus will reside dormant in the patient’s liver and symptoms may begin appearing over a period of 10 to 20 years. It is estimated that 25 to 35 percent of chronic carriers of hepatitis C will develop progressive liver disease including cirrhosis and liver cancer. Many of them will require liver transplants since hepatitis C is the leading cause of liver transplantation. A high percentage will eventually die from liver-related complications. The Center for Disease Control estimates that in the year 2000, about 10,000 people died from hepatitis C in the United States alone. It is predicted that by the end of this decade, the number of hepatitis C deaths in the United States will surpass the number of deaths from AIDS.

How did this deadly virus spread so dramatically? Hepatitis C spreads through contact with contaminated blood. One mode of transmission is sharing of contaminated needles, but the main mode of transmission for decades has been blood transfusions. Only in 1992 did authorities mandate standard screening of blood donations for hepatitis C. Reliable tests to detect the virus did not exist prior to 1992, since the very existence of the hepatitis C virus was discovered for the first time only in 1986.

There is no vaccine available against hepatitis C, and the only available treatment today for chronic patients is Interferon Alpha. Interferon Alpha is not very effective, especially among U.S. patients, who are usually infected with a highly resistant strain of the virus. Interferon therapy is associated with devastating effects on the patients and, consequently, their families. The patient is in a constant state of fever while taking Interferon and, as a result, the majority of patients cannot work. Most patients receiving interferon therapy suffer from depression as a side effect of the treatment. In many cases they become suicidal.

One of the major challenges of medicine is to develop alternatives to Interferon – therapeutics against hepatitis C that are more effective than Interferon, without its side effects.

One promising approach to treat hepatitis C is the use of monoclonal antibodies. What are monoclonal antibodies? They are proteins designed to function in the same way the body’s natural immune system defends itself against foreign organisms. Monoclonal antibodies specifically recognize a foreign organism that has invaded the body, bind to it, neutralize it, and clear it from the body. Monoclonal antibodies are very safe, and since they are specific, they do not cause any side effects. Advances in immunology and genetic engineering that took place in the ’90s made the use of monoclonal antibodies, one of the most promising therapeutic approaches to fighting disease. Ten monoclonal antibody drugs are already marketed for treatment of various conditions from breast cancer and leukemia to rheumatoid arthritis and blood clotting. There are 100 additional monoclonal antibodies in clinical trials.

The only monoclonal antibody therapeutic against hepatitis C now in clinical trials is XTL-002, a drug developed in Rehovot, Israel, by a biotech company called XTL. What allowed XTL to accomplish this leadership position in the field of hepatitis C is a unique technology called Trimera, which was developed at the Weizmann Institute of Science – Israel’s most prestigious life science research institute. Trimera allows XTL not only to develop monoclonal antibodies against various infectious diseases, but also to evaluate their effect on the disease prior to entering clinical trials in patients. In pre-clinical trials, XTL-002 substantially reduced the level of the hepatitis C virus using the world’s most advanced hepatitis C disease models. It is now being tested in patients who are chronic carriers of the hepatitis C virus. XTL will release data from this clinical trial in early 2002. If XTL-002 demonstrates the same anti-viral effect it had in pre-clinical studies in these chronic patients, then there is new hope for millions worldwide for a safe and effective therapy for hepatitis C – with no side effects.