Hepatitis C Virus
Consequences for the Individual and Society
International experts indicate that nearly 70% of people infected with HCV develop a chronic liver infection, which can remain in the body for many decades. A small number of patients resolve chronic infections spontaneously, but the virus remains in the vast majority and can then result in serious liver damage. Chronic HCV infections are now the most common cause of liver transplantation in the West. Apart from the purely physical symptoms, chronic HCV infection can put the patient under psychological strain.
Estimates indicate that the patient population with serious liver damage caused by HCV will increase sharply over the next 20 years, as will the number of treatments and social cost for treatment. Accordingly, developing new types of treatment is an important issue.
Existing Therapies
Certain types of chronic HCV infection caused by viruses termed genotype 2 or 3 can already be treated quite successfully. Some 80% of patients can be cured by combining interferon and ribavirin for 24 weeks. The fact that this infection is curable is almost unique for virus infections. However, the most common form of HCV, genotype 1, is far harder to treat. Approximately 50% of all HCV infections in Sweden are of genotype 1, and up to 70% in Europe and the US. Existing therapies enable 40-50% of genotype 1 infections to be cured. The cost of therapy is approximately SEK 200,000 per patient. Existing therapy can cause side-effects such as pronounced tiredness and serious depression. Overall, this means that there is a great need for new types of therapy.
The Body's Capacity to Cure
Over the last 10-15 years, a number of suspected contributory factors to spontaneous clearance of HCV infection have been identified. One of the most important seems to be the body's ability to generate an immune response to the infection rapidly and effectively. Research indicates that the people resolving HCV infection spontaneously form a strong immune response to various HCV proteins, and particularly against one called nonstructural 3 (NS3), an important component of ChronVac-C®. Chronic infection develops in people who, for some reason, are unable to generate a strong response. More recent research has been able to demonstrate that the immune response to HCV is activated by interferon and ribavirin treatment of chronic HCV infections, and that this immune response remains, particularly in those cured by therapy. Overall, this suggests that activation of the body's immune response can result in a resolution of the infection, and the patient being cured. This, in turn, indicates that therapies that can activate the body's own immune response against HCV, similar to interferon treatment, could constitute a new type of therapy for chronic HCV infections.
Market
In 2004, the total market for drugs against HCV infections was worth over USD 2 bn, and is currently dominated by Schering-Plough and Roche with their pegylated interferons, called PegIntron and Pegasys respectively. Robust market growth is expected in coming years, with the primary drivers being enhancements and improvements of interferons and ribavirin.
At present, drugs against HCV infection are being developed that impact the virus directly, inhibiting its capacity to replicate or infect new cells. They are termed antivirals, and are very reminiscent of extant HIV compounds. As yet, they are in relatively early development, and are expected to reach the market in 2011-2013. Antiviral drugs are expected to mark a paradigm shift in the treatment of chronic HCV infections, estimated to represent over one-third of the total market for pharmaceuticals against chronic HCV infections by 2013. But their potential remains uncertain, because no clear clinical benefit has been demonstrated yet.
An entirely novel class of drugs, separate from the above antivirals and called therapeutic vaccines, are in development. Hopefully, such vaccines will be administered early in the course of the illness, thus replacing interferons as first-line therapy. Moreover, there are good chances that such vaccines could be used prophylactically, to prevent new HCV infections. If a therapeutic vaccine like ChronVac-C® could be demonstrated to offer comprehensive protection against HCV infections, this would probably revolutionise the market for the treatment of HCV infections.