XTLbio's HCV human MAbs patent

Israeli biotech company XTL Biopharmaceuticals has been issued a patent entitled, 'Prevention and treatment of HCV infection employing antibodies that inhibit the interaction of HCV virions with their receptor'.

The patent covers human monoclonal antibodies (MAbs) directed against the envelope glycoprotein 2 (E2) of the hepatitis C virus (HCV). The patent was recently licensed from Stanford University. The Mabs disclosed in the patent include a potent neutralising antibody that could potentially enhance XTLbio's treatment candidate, HepeX-C, also a human monoclonal antibody based product, currently in phase II clinical studies in liver transplant patients. HepeX-C has shown anti-viral activity in phase I studies in chronic HCV patients. In line with XTLbio's previously announced strategy in HCV liver transplant, XTLbio intends to submit an IND for a combination of HepeX-C with one of the newly licenced antibodies later this year. The addition of a second antibody could increase the potency of the product by minimising emergence of viral escape mutants and /or enhancing anti-viral activity.

About hepatitis C

Hepatitis C is a major public health concern. The World Health Organisation estimates that 170m people worldwide are chronic carriers of the hepatitis C virus (HCV) and that 3 to 4m people are newly infected each year. It is expected that 25 to 35% of these chronic patients will develop progressive liver disease including cirrhosis and liver cancer. Hepatitis C is the single leading cause of liver transplantation. The US Centres for Disease Control and Prevention estimate that approximately 4m people in the US (almost 2% of the population) have been infected with HCV, of whom, approximately 3m are chronically ill. Hepatitis C is the cause of an estimated 8,000 to 10,000 deaths annually in the US.

HCV-related liver transplant prophylaxis

Approximately 5% of chronic HCV patients will develop end-stage liver disease, and ultimately may require liver transplantation. Today, there is a major problem associated with HCV-related liver transplantation. Although the infected liver - the major source of viral replication - has been removed, free-floating virus in the patient's serum re-infects the healthy transplanted liver in a matter of weeks. Disease progression in re-infected patients is several times faster and, in many cases, a re-transplant becomes necessary. At present, there is no available solution to this problem.

Treatment of chronic hepatitis C

The existing first-line chronic HCV therapy is often associated with a 50-60% success rate but it is limited by severe side effects, including anaemia, fatigue, hair loss and depression. Due to the relatively limited efficacy and toxicity of this treatment, chronic HCV is still considered to be an unmet medical need, with estimated worldwide annual sales for all products treating chronic hepatitis C reaching US$4bn in 2004.