Hepatitis C is a liver infection caused by the hepatitis C virus (HCV) that can lead to chronic illness, liver damage, and even liver cancer if left untreated. The virus is primarily transmitted through exposure to infectious blood. In the past, interferon was a primary treatment option for individuals living with this viral infection.
What is Interferon and How it Works
Interferon is a protein produced by the body’s immune system in response to viruses. It functions as an immunomodulator, influencing cell growth and division, and modulating immune system activities.
Interferon works by binding to specific receptors on target cells, activating an intracellular signaling cascade. This activation leads to the induction of interferon-stimulated genes (ISGs), which establish an antiviral state within the cell. These ISGs produce antiviral proteins that inhibit viral replication by blocking viral RNA translation and causing degradation of viral mRNA and tRNA. Interferon also enhances the functions of immune cells such as natural killer cells, T-cells, and macrophages, aiding the body’s defense against the Hepatitis C virus.
Administering Treatment and Managing Side Effects
Interferon alpha was administered through subcutaneous or intramuscular injections, either daily or three times a week. Treatment duration ranged from 6 to 24 months, depending on the specific regimen and patient factors. A significant advancement was the introduction of pegylated interferon, which allowed for once-weekly injections due to its slower elimination from the body, maintaining more stable serum concentrations.
Interferon therapy was associated with a wide array of side effects, which were often challenging for patients. Common early side effects, often described as flu-like symptoms, included fever, headache, fatigue, chills, malaise, and muscle and joint pain. These symptoms typically appeared within 6 to 8 hours after the initial injection and were most pronounced with the first few doses.
Over longer treatment periods, patients could experience persistent side effects such as chronic fatigue, apathy, and cognitive changes. Neuropsychiatric effects, including depression, irritability, anxiety, and confusion, were particularly troublesome and could be severe enough to necessitate treatment discontinuation. Interferon also had myelosuppressive effects, leading to decreases in granulocyte, platelet, and red blood cell counts. Autoimmune phenomena could also be induced or aggravated by therapy.
Interferon’s Place in Modern Hepatitis C Care
Interferon was once the standard treatment for Hepatitis C. Initial monotherapy regimens achieved sustained virologic response (SVR) in only about 8% to 9% of patients. The addition of ribavirin, an antiviral drug, significantly improved success rates, reaching approximately 40% to 50% SVR, with pegylated interferon further boosting this to about 50% to 60%. For HCV genotypes 2 or 3, combination therapy with pegylated interferon and ribavirin could achieve SVR rates of 80% to 90% over 24 weeks, while genotype 1 and 4 infections had lower rates of about 50% over 48 weeks.
The landscape of Hepatitis C treatment has undergone a significant transformation with the advent of direct-acting antiviral (DAA) medications. DAAs specifically target viral proteins necessary for HCV replication, offering substantially higher cure rates, often exceeding 95% across various genotypes. These newer therapies are also associated with shorter treatment durations, typically 8 to 12 weeks, and an improved side effect profile compared to interferon-based regimens. Consequently, interferon-free DAA regimens have largely replaced interferon as the standard of care for Hepatitis C, though interferon-based treatments may still be considered in rare, resource-limited settings.