Interferon alfa
Also known as: Alferon, Alferon N, IFN-α, IFN‑α2a, IFN‑α2b, Infergen, interferon alpha, Intron A, Pegasys, Roferon-A, Roferon‑A
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Summary
Interferon alfa is a prescription type I interferon cytokine used as an immunomodulatory therapy for certain viral infections (notably chronic hepatitis B and C) and selected cancers such as Kaposi's sarcoma, renal cell carcinoma and, historically, metastatic melanoma. It is administered by injection and can be formulated as standard or pegylated preparations to extend its activity.
Mechanism of Action
Interferon alfa binds the heterodimeric IFN‑α/β receptor (IFNAR1/2) on target cells, activating the JAK‑STAT signaling cascade. Phosphorylated STAT1/2 combine with IRF9 to form the ISGF3 complex, which translocates to the nucleus and drives expression of interferon‑stimulated genes. These genes create an antiviral state, enhance antigen presentation, inhibit cell proliferation, and promote apoptosis of infected or malignant cells.
What the Research Shows
Systematic reviews of metastatic melanoma have evaluated interferon alfa added to chemotherapy, but the evidence does not demonstrate a clear survival benefit. In chronic hepatitis B, a meta‑analysis of pegylated interferon alfa showed improved virological and serological responses, especially when combined with nucleos(t)ide analogues. For chronic hepatitis C, interferon alfa (often pegylated) remains a cornerstone of therapy, though newer agents are now preferred. A meta‑analysis of eight trials found that prophylactic antidepressants halve the risk of interferon‑induced major depression in melanoma and hepatitis C patients. Evidence for optimal dosing in cancer indications remains limited, and many conclusions derive from pooled analyses rather than large, contemporary RCTs.
Reported Benefits
Clinical data support interferon alfa as an effective antiviral for chronic hepatitis B and C, improving viral clearance and seroconversion, particularly when used as pegylated formulations alongside nucleos(t)ide analogues. It is also the treatment of choice for chronic active hepatitis B, chronic hepatitis C, and AIDS‑related Kaposi's sarcoma, and shows activity against metastatic renal carcinoma and chronic myelogenous leukaemia. Antidepressant pretreatment can markedly reduce interferon‑associated depression, enhancing tolerability.
Limitations of the Evidence
In metastatic melanoma, interferon alfa has not shown a definitive survival advantage and its role remains controversial. Optimal dose regimens for many oncologic uses are unclear, and most evidence comes from systematic reviews rather than recent large‑scale trials. Newer direct‑acting antivirals have largely supplanted interferon‑based regimens for hepatitis C, limiting its current relevance. Data on long‑term outcomes are sparse, and many studies involve pegylated versions, which may differ from standard interferon alfa.
Safety Considerations
Common adverse effects include flu‑like symptoms, fatigue, hematologic suppression (leukopenia, thrombocytopenia), and neuropsychiatric disturbances, particularly depression. The meta‑analysis of antidepressant pretreatment indicates that selective serotonin reuptake inhibitors can lower the incidence and severity of interferon‑related depression. Monitoring of blood counts and mood symptoms is advised, and dose adjustments may be needed for severe toxicity.
How It Is Administered
Interferon alfa is delivered by injection via intramuscular, subcutaneous, intravenous, or intralesional routes, depending on the indication and formulation. Pegylated preparations allow less frequent dosing (often weekly) compared with standard daily injections. Specific dosing schedules vary by disease and are determined by the prescribing clinician.
Routes of Administration
Goals & Uses
- Chronic Hepatitis C treatmentAntiviralHigh
- Viral suppressionAntiviralHigh
- Chronic Hepatitis B treatmentAntiviralHigh
- Melanoma adjuvant therapyOncologyHigh
- ImmunomodulationImmunologyModerate
- Tumor growth inhibitionOncologyHigh
- Hairy cell leukemia treatmentOncologyHigh
- Kaposi's sarcoma treatmentOncologyModerate
- Follicular lymphoma treatmentOncologyModerate
Contraindications
- Decompensated liver disease (Child-Pugh B/C)HepaticHigh
- Severe autoimmune diseaseImmunologicalHigh
- Severe psychiatric disorder (untreated)PsychiatricHigh
- Neonates (formulations with benzyl alcohol)PediatricHigh
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- Severe depression or psychiatric illnessPsychiatricHigh
- Hypersensitivity to interferon alfaImmunologicHigh
- Autoimmune hepatitisHepatic / AutoimmuneHigh
Adverse Effects
- Neutropenia and thrombocytopeniaHematologicCommon
- Injection site reactionsLocalCommon
- Autoimmune thyroiditisEndocrineRare
- Thyroid dysfunction (hyper- or hypothyroidism)EndocrineUncommon
- Flu-like syndrome (fever, chills, myalgia, fatigue)SystemicCommon
- Depression and suicidal ideationPsychiatricCommon
- DepressionPsychiatricCommon
- Hematologic abnormalities (leukopenia, thrombocytopenia)HematologicUncommon
- Elevated liver enzymesHepaticUncommonIncrease in AST/ALT or other hepatic markers
- Flu‑like syndrome (fever, myalgia)SystemicCommon
- RetinopathyOphthalmologicUncommon
Drug Interactions
- RituximabModerate
- Live vaccinesHigh
- Zidovudine (AZT)Moderate
- Immunosuppressants (e.g., tacrolimus, cyclosporine)Moderate
- RibavirinModerate
- CorticosteroidsModerate
- ClozapineHigh
- TheophyllineHigh
- MethadoneModerate
Population Constraints
- Patients with severe renal impairment (CrCl <50 mL/min)RenalRelative
- Renal impairmentOrgan ImpairmentRelative
- Elderly (>65 years)AgeRelative
- Patients with pre-existing autoimmune disordersImmunologicRelative
- Pediatric patientsAgeRelative
- Pediatric patients (<1 year)AgeAbsolute
- Pregnant womenReproductiveRelative
- Patients with pre-existing cardiac diseaseCardiovascularRelative
- Elderly (>75 years)GeriatricRelative
Regulatory Status
- European UnionApprovedApproved: Chronic hepatitis B, Chronic hepatitis C, Chronic myeloid leukemia, MelanomaApproved under EMA with similar indications as US.
- United StatesApprovedApproved: Chronic hepatitis B, Chronic hepatitis C, Hairy cell leukemia, Melanoma (adjuvant), Renal cell carcinomaMultiple formulations (IFN‑α2a, IFN‑α2b, pegylated) approved.
- United KingdomApprovedApproved: Chronic hepatitis B, Chronic hepatitis C, Hairy cell leukemia, Renal cell carcinomaRegulated by MHRA.
Approved in multiple jurisdictions for viral hepatitis, chronic myelogenous leukemia, melanoma, and as adjunct therapy in solid tumors. Pegylated forms have extended half‑life.
Evidence & Sources
- Journal ArticleHighLarkin J, Gore M2008-01-01T00:00:00.000000Z
- Journal ArticleModerateWilliams CD, Linch DC1997-01-01T00:00:00.000000Z
- Journal ArticleHighSarkar S, Schaefer M2014-01-01T00:00:00.000000Z
- Journal ArticleHighKim V, et al.2016-01-01T00:00:00.000000Z
- Journal ArticleHighFisher RA, Larkin J2010-01-01T00:00:00.000000Z
- Journal ArticleModerateHochhaus A, et al.2017-01-01T00:00:00.000000Z
Frequently Asked Questions
What conditions is interferon alfa approved to treat?
It is approved for chronic active hepatitis B, chronic hepatitis C, and AIDS‑related Kaposi's sarcoma, and has demonstrated activity in certain cancers such as renal cell carcinoma and chronic myelogenous leukaemia.
Why does interferon alfa cause depression?
Interferon alfa stimulates cytokine pathways that can affect neurotransmitter systems, leading to mood changes. A systematic review found that prophylactic antidepressants halve the risk of major depression during treatment.
How does pegylation change interferon alfa?
Pegylation attaches a polyethylene glycol chain, prolonging the drug’s half‑life and allowing less frequent injections, while preserving antiviral and immunomodulatory activity.
Is interferon alfa still used for hepatitis C?
It remains an option, especially where newer direct‑acting antivirals are unavailable, but current guidelines favor newer agents due to higher efficacy and better tolerability.
What monitoring is required during therapy?
Regular blood counts to detect leukopenia or thrombocytopenia, liver function tests, and assessment of mood or depressive symptoms are recommended throughout treatment.
What is Interferon alfa?
Interferon alfa is a prescription type I interferon cytokine used as an immunomodulatory therapy for certain viral infections (notably chronic hepatitis B and C) and selected cancers such as Kaposi's sarcoma, renal cell carcinoma and, historically, metastatic melanoma. It is administered by injection and can be formulated as standard or pegylated preparations to extend its activity.
What is Interferon alfa used for?
Interferon alfa is educationally associated with: Chronic Hepatitis C treatment, Viral suppression, Chronic Hepatitis B treatment, Melanoma adjuvant therapy, Immunomodulation, Tumor growth inhibition, Hairy cell leukemia treatment, Kaposi's sarcoma treatment, Follicular lymphoma treatment. Educational only — not medical advice.
How is Interferon alfa administered?
Recorded routes of administration: Intralesional, Intramuscular, Intravenous, Subcutaneous.
What are the potential side effects of Interferon alfa?
Reported adverse effects include: Neutropenia and thrombocytopenia, Injection site reactions, Autoimmune thyroiditis, Thyroid dysfunction (hyper- or hypothyroidism), Flu-like syndrome (fever, chills, myalgia, fatigue), Depression and suicidal ideation, Depression, Hematologic abnormalities (leukopenia, thrombocytopenia), Elevated liver enzymes, Flu‑like syndrome (fever, myalgia), Retinopathy. This list is not exhaustive — consult a qualified clinician.
Who should avoid Interferon alfa?
Recorded contraindications: Decompensated liver disease (Child-Pugh B/C), Severe autoimmune disease, Severe psychiatric disorder (untreated), Neonates (formulations with benzyl alcohol), Pregnancy, Severe depression or psychiatric illness, Hypersensitivity to interferon alfa, Autoimmune hepatitis. Consult a qualified clinician before use.