Interferon alfa-2a
Also known as: IFN-α2a, IFN‑A2a, IFN‑α2a, Interferon alpha-2a, NSC-367982, Pegasys, rIFN-α2a, Roferon-A, Roferon‑A
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Summary
Interferon alfa‑2a is a recombinant type I interferon approved for prescription use. It is administered by injection and acts as an antiviral and immunomodulatory cytokine. Clinically it is employed as a pegylated formulation for chronic hepatitis B combination therapy and as cytoreductive treatment in myeloproliferative neoplasms such as polycythaemia vera and essential thrombocythemia.
Mechanism of Action
Interferon alfa‑2a binds the interferon‑α/β receptor (IFNAR) on target cells, activating the JAK‑STAT signaling cascade. This induces expression of interferon‑stimulated genes that produce antiviral, antiproliferative and immunomodulatory effects, including inhibition of viral replication and suppression of abnormal clonal hematopoietic growth. The resulting proteins enhance innate immunity and help control disease processes.
What the Research Shows
Recent clinical data illustrate two main therapeutic contexts. In a phase‑2 platform trial of chronic hepatitis B, adding pegylated interferon alfa‑2a (180 µg) to the siRNA agent xalnesiran produced hepatitis B surface antigen loss in 23 % of participants, whereas nucleos(t)ide analogue alone achieved none; however, grade 3‑4 adverse events occurred in half of the combination group, most commonly elevated alanine aminotransferase. In myeloproliferative disorders, European LeukemiaNet 2021 guidelines endorse pegylated interferon alfa‑2a as a preferred cytoreductive option for younger polycythaemia vera patients without prior thrombosis. Supporting this, a phase‑2 multicentre trial in hydroxyurea‑refractory essential thrombocythemia and polycythaemia vera reported overall response rates of 69 % and 60 % respectively after 12 months, with higher complete responses in CALR‑mutated essential thrombocythemia and manageable toxicity leading to discontinuation in 13.9 % of cases.
Reported Benefits
Evidence shows pegylated interferon alfa‑2a can induce serologic cure in chronic hepatitis B when combined with an siRNA, achieving HBsAg loss in a notable minority of patients. In polycythaemia vera and essential thrombocythemia, it yields high hematologic response rates, particularly complete remissions in CALR‑mutated disease, and offers a non‑chemotherapy cytoreductive alternative for younger patients, aligning with expert guideline recommendations.
Limitations of the Evidence
Data are limited to phase‑2 studies and guideline consensus rather than large‑scale phase‑3 trials, leaving long‑term efficacy and comparative effectiveness uncertain. The hepatitis B benefit was observed only in combination with another investigational agent, and serious adverse events were frequent. In myeloproliferative neoplasms, response variability exists, and the need for injectable therapy may limit adherence. Overall, robust, randomized controlled data across broader populations are lacking.
Safety Considerations
Pegylated interferon alfa‑2a is associated with grade 3‑4 adverse events in up to 50 % of patients when used with xalnesiran, the most common being elevated alanine aminotransferase. In myeloproliferative trials, adverse events were generally manageable, but treatment discontinuation occurred in about 14 % of participants. Reported toxicities include flu‑like symptoms, laboratory abnormalities, and potential hematologic effects; careful monitoring of liver enzymes and blood counts is advised.
How It Is Administered
Interferon alfa‑2a is supplied for injection and may be given intramuscularly, intravenously, or subcutaneously. The pegylated formulation is typically administered by subcutaneous injection on a weekly schedule, though exact dosing regimens depend on the indication and prescribing information.
Routes of Administration
Goals & Uses
- AIDS-Related Kaposi's SarcomaOncology / Infectious DiseaseModerate
- Chronic Hepatitis C Antiviral TreatmentInfectious Disease / AntiviralHigh
- Melanoma (adjuvant)OncologyModerate
- Chronic hepatitis CAntiviralHigh
- Hairy‑cell leukemiaAntineoplasticHigh
- Antiviral ImmunomodulationImmunologyModerate
- Chronic myelogenous leukemia (CML)OncologyHigh
- Hairy cell leukemia treatmentOncologyHigh
- Chronic hepatitis BAntiviral / HepatologyModerate
- Follicular LymphomaOncologyModerate
Contraindications
- Severe Psychiatric Disorders (e.g., severe depression, suicidality)PsychiatricHigh
- Hypersensitivity to interferon alfa or formulation componentsImmunologicHigh
- Known hypersensitivity to interferon‑α2a or excipientsAllergyHigh
- Severe autoimmune diseaseImmunologicalHigh
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- Neonates and Infants (benzyl alcohol-containing formulations)PediatricHigh
- Severe depression or psychiatric illnessPsychiatricModerate
- Autoimmune hepatitisHepatic / AutoimmuneHigh
- Decompensated liver diseaseHepatic ImpairmentHigh
Adverse Effects
- Depression / suicidal ideationPsychiatricModerate
- Injection site reactionsLocalCommon
- ThrombocytopeniaHematologicCommonLow platelet count
- Hepatotoxicity / Transaminase ElevationHepaticCommon
- NeutropeniaHematologicCommonLow neutrophil count
- Myelosuppression (neutropenia, thrombocytopenia, anemia)HematologicCommon
- Flu‑like syndrome (fever, myalgia, fatigue)SystemicCommon
- Elevated liver enzymesHepaticCommonIncrease in AST/ALT or other hepatic markers
- Flu-like SyndromeSystemic / ConstitutionalCommon
- Thyroid dysfunction (hypo- or hyperthyroidism)EndocrineUncommon
- Neuropsychiatric Effects (depression, irritability, suicidality)Psychiatric / NeurologicalCommon
Drug Interactions
- Live attenuated vaccinesHigh
- Zidovudine (AZT)High
- Immunosuppressants (e.g., cyclosporine)Moderate
- RibavirinModerate
- ClozapineHigh
- TheophyllineModerate
- MethadoneModerate
Population Constraints
- PregnancyReproductive SafetyRelative
- Cardiac DiseaseCardiovascularRelative
- Renal impairmentOrgan ImpairmentRelative
- Pediatric patientsAgeRelative
- Pre-existing Psychiatric ConditionsPsychiatricRelative
- Elderly patientsAgeRelative
- Pregnant womenReproductiveAbsolute
- Pediatric patients (<1 yr)AgeRelative
Regulatory Status
- European UnionApprovedApproved: Chronic hepatitis C, Chronic hepatitis B, Hairy-cell leukemia, MelanomaEMA approval; similar indications as US.
- United StatesApprovedApproved: Chronic hepatitis C, Hairy-cell leukemia, Melanoma (adjuvant)FDA approval under brand Roferon‑A; pegylated form (Pegasys) also approved.
- United KingdomApprovedApproved: Chronic hepatitis C, Hairy-cell leukemia, MelanomaMHRA approval.
FDA‑approved (Roferon‑A) for hepatitis C (in combination with ribavirin), hairy‑cell leukemia, and melanoma; also approved in EU and UK.
Evidence & Sources
- Journal ArticleModerateHou J, et al.2024-01-01T00:00:00.000000Z
- Journal ArticleModerateMarchetti M, et al.2022-01-01T00:00:00.000000Z
- Journal ArticleModerateYacoub A, et al.2019-01-01T00:00:00.000000Z
Frequently Asked Questions
For which diseases is interferon alfa‑2a currently used?
Approved formulations are used as a pegylated injectable for chronic hepatitis B in combination regimens and as a cytoreductive therapy in polycythaemia vera and essential thrombocythemia, particularly in younger patients without prior thrombosis.
How does interferon alfa‑2a work against hepatitis B?
When combined with an siRNA that silences HBV transcripts, pegylated interferon alfa‑2a enhances immune clearance, leading to loss of hepatitis B surface antigen in a subset of patients, although the effect is observed only in the combination setting.
What are the main side effects to watch for?
Serious adverse events can include elevated liver enzymes (alanine aminotransferase), flu‑like symptoms, and laboratory abnormalities. In myeloproliferative studies, about 14 % stopped treatment due to toxicity, so regular monitoring of liver function and blood counts is recommended.
Is interferon alfa‑2a curative for polycythaemia vera?
Current evidence shows it can achieve high hematologic response rates and some complete remissions, especially in CALR‑mutated disease, but long‑term cure has not been demonstrated and treatment often requires ongoing administration.
How is the drug given?
The medication is supplied for injection and can be administered intramuscularly, intravenously, or subcutaneously. The pegylated form is most commonly given by subcutaneous injection, usually on a weekly basis, according to prescribing guidelines.
What is Interferon alfa-2a?
Interferon alfa‑2a is a recombinant type I interferon approved for prescription use. It is administered by injection and acts as an antiviral and immunomodulatory cytokine. Clinically it is employed as a pegylated formulation for chronic hepatitis B combination therapy and as cytoreductive treatment in myeloproliferative neoplasms such as polycythaemia vera and essential thrombocythemia.
What is Interferon alfa-2a used for?
Interferon alfa-2a is educationally associated with: AIDS-Related Kaposi's Sarcoma, Chronic Hepatitis C Antiviral Treatment, Melanoma (adjuvant), Chronic hepatitis C, Hairy‑cell leukemia, Antiviral Immunomodulation, Chronic myelogenous leukemia (CML), Hairy cell leukemia treatment, Chronic hepatitis B, Follicular Lymphoma. Educational only — not medical advice.
How is Interferon alfa-2a administered?
Recorded routes of administration: Intramuscular, Intravenous, Subcutaneous.
What are the potential side effects of Interferon alfa-2a?
Reported adverse effects include: Depression / suicidal ideation, Injection site reactions, Thrombocytopenia, Hepatotoxicity / Transaminase Elevation, Neutropenia, Myelosuppression (neutropenia, thrombocytopenia, anemia), Flu‑like syndrome (fever, myalgia, fatigue), Elevated liver enzymes, Flu-like Syndrome, Thyroid dysfunction (hypo- or hyperthyroidism), Neuropsychiatric Effects (depression, irritability, suicidality). This list is not exhaustive — consult a qualified clinician.
Who should avoid Interferon alfa-2a?
Recorded contraindications: Severe Psychiatric Disorders (e.g., severe depression, suicidality), Hypersensitivity to interferon alfa or formulation components, Known hypersensitivity to interferon‑α2a or excipients, Severe autoimmune disease, Pregnancy, Neonates and Infants (benzyl alcohol-containing formulations), Severe depression or psychiatric illness, Autoimmune hepatitis, Decompensated liver disease. Consult a qualified clinician before use.