Interferon Alfa: Uses & Side Effects

Interferon alfa is a family of proteins and
glycoproteins with antiviral, antineoplastic, and immunomodulating activities.
Available in America as interferon alfa-2b and interferon alfa-n3. Also
available covalently bound to monomethoxy polyethylene glycol (PEG) (i.e.,
peginterferon alfa).

Uses for Interferon Alfa

Chronic HBV Infection

Interferon alfa-2b: Treatment of chronic
HBV infection in adults, adolescents, and children ≥1 year of age with
compensated liver disease.

Goal of antiviral therapy is sustained
suppression of HBV replication and remission of liver disease; long-term goal
is prevention of cirrhosis, hepatic failure, and hepatocellular carcinoma.

Currently available therapies (e.g.,
interferon alfa, peginterferon alfa, adefovir, entecavir, lamivudine,
telbivudine, tenofovir) do not eradicate HBV and may have only limited
long-term efficacy. When making decisions regarding treatment, consider
patient’s age, severity of liver disease, likelihood of response, safety and
efficacy of the drug, potential for selection of resistant HBV strains,
potential for adverse reactions, costs, patient’s pregnancy potential, and
patient and provider preferences.

American Association for the Study of Liver
Diseases (AASLD) states that drugs of choice for initial treatment of chronic
HBV infection in patients with compensated liver disease are peginterferon
alfa, entecavir, or tenofovir, unless contraindicated or ineffective. Efficacy
of peginterferon alfa and nonconjugated interferon alfa are considered similar,
but peginterferon alfa dosage schedule more convenient and generally preferred.

Treatment of chronic HBV infection is
complex and rapidly evolving and should be directed by clinicians familiar with
the disease; consult specialist to obtain the most up-to-date information.

Chronic HCV Infection

Interferon alfa-2b: Has been used for
treatment of chronic HCV infection in adults with compensated liver disease;
used alone or in conjunction with oral ribavirin.

Interferon alfa-2b: Has been used for
treatment of chronic HCV infection in treatment-naive children ≥3 years of age
with compensated liver disease; used in conjunction with oral ribavirin.

Peginterferon alfa (not interferon alfa)
recommended if an interferon is used for treatment of chronic HCV infection.
Interferon alfa alone or in conjunction with oral ribavirin associated with
lower response rates than peginterferon alfa in conjunction with oral
ribavirin.

Treatment of chronic HCV infection is
complex and rapidly evolving; consult a specialist to obtain the most
up-to-date information.

Chronic HDV Infection

Interferon alfa: Has been used with some
limited success for treatment of chronic HDV infection in adults and children
coinfected with HBV. Although interferon alfa may suppress viral activity in
some patients, sustained response not obtained and relapse generally occurs
after drug discontinued.

HDV infection only occurs in individuals
with HBV infection since the virus depends on HBV for production of envelope
proteins. Can be acquired as a coinfection with HBV or as a superinfection in
HBV carriers. HDV superinfection in HBV carriers almost always results in
chronic infection with both viruses and is associated with high risk of
cirrhosis, hepatic decompensation, and hepatocellular carcinoma.

Human Papillomavirus (HPV) Infections

Interferon alfa-2b, interferon alfa-n3:
Intralesional treatment of external genital and perianal exophytic warts
(condylomata acuminata) caused by HPV.

CDC states that intralesional interferon
alfa is an alternative (not preferred) option for treatment of external HPV
warts because of higher frequency of adverse effects (including rare severe
systemic adverse effects) and/or less efficacy data compared with other
options.

No currently available option has been
shown to eradicate HPV infectivity.

West Nile
Virus Infection

Interferon
alfa-2b, interferon alfa-n3: Have been investigated for treatment of serious
West Nile virus (WNV) infection.

Despite initial
case reports suggesting some clinical benefits in neuroinvasive disease, efficacy
not proven in controlled clinical trials. Unlikely to inhibit WNV replication
following establishment of infection.

Hairy Cell
Leukemia

Interferon
alfa-2b: Treatment of hairy cell leukemia (leukemic reticuloendotheliosis).

Complete response
achieved in 10% of patients and overall response achieved in approximately 80%
of patients.

An alternative
for hairy cell leukemia; cladribine or pentostatin preferred (achieve higher
complete response rates than interferon alfa).

AIDS-related
Kaposi’s Sarcoma

Interferon
alfa-2b: Palliative treatment of AIDS-related Kaposi’s sarcoma in selected
adults (designated an orphan drug by FDA for this indication).

Do not use in
patients with rapidly progressive visceral or life-threatening disease; response
generally is slow and poor.

Likelihood of
response to interferon alfa is greater in patients without systemic symptoms
who have limited lymphadenopathy and relatively intact immune systems as
indicated by CD4+ T-cell counts.

All patients with
AIDS-related Kaposi’s sarcoma should be receiving highly active antiretroviral
therapy; in some patients, initiation of antiretroviral therapy alone may
result in tumor regression and resolution of lesions.

Non-Hodgkin’s
and Cutaneous T-cell Lymphomas

Interferon
alfa-2b: Although labeled by FDA for use in conjunction with an anthracycline
for initial treatment of clinically aggressive follicular non-Hodgkin’s
lymphoma in adults, other agents preferred.

Efficacy in patients with low-grade,
low-tumor-burden follicular non-Hodgkin’s lymphoma not demonstrated.

Interferon alfa: Has been used for
treatment of cutaneous T-cell lymphomas.

Melanoma

Interferon alfa-2b: Used as an adjunct to
surgery (within 56 days of surgery) in adults with malignant melanoma who are
disease free but at high risk for systemic recurrence.

Palliative treatment of metastatic melanoma
in selected patients, alone and in conjunction with other therapies (e.g.,
radiation).

Basal Cell and Squamous Cell Skin
Cancers

Interferon alfa: Has been used
intralesionally for treatment of basal cell carcinoma and squamous cell
carcinoma.

Chronic Myelogenous Leukemia

Interferon alfa-2b: Has been used for
treatment of adult-type (Philadelphia chromosome-positive) chronic myelogenous
(myelocytic, myeloid) leukemia (CML).

Renal Cell Carcinoma

Interferon alfa: Has been used for
treatment of metastatic renal cell carcinoma
in selected patients.

Bladder Cancer

Interferon alfa: Has been used
intravesically for prophylaxis or treatment of superficial bladder cancer.

Ovarian Cancer

Interferon alfa: Has been used intraperitoneally
for treatment of minimal residual epithelial ovarian cancer in a limited number
of patients.

Contraindications

Interferon alfa-2a (Intron A): Known
hypersensitivity (e.g., urticaria, angioedema, bronchoconstriction,
anaphylaxis) to interferon alfa or any ingredient in the formulation.

Interferon alfa-n3 (Alferon N): Known
hypersensitivity to human interferon alfa proteins or any component in the
formulation; history of anaphylactic reactions to murine (mouse) IgG, egg
protein, or neomycin.

Interferon alfa-2b: Autoimmune hepatitis or
hepatic decompensation (Child-Pugh score >6, class B and C).

Interferon alfa-2b: Concomitant use of oral
ribavirin contraindicated in women who are or may become pregnant, men whose
female partners are pregnant, patients with known hypersensitivity to ribavirin
or any ingredient in the formulation, patients with hemoglobinopathies (e.g.,
thalassemia major, sickle cell anemia), and patients with Clcr
<50 mL/minute.

Common Adverse Effects

  • Flu-like symptoms (e.g., fever, headache, chills, myalgia/arthralgia,
    fatigue, increased sweating, asthenia, rigors, dizziness)
  • Abdominal pain
  • Alopecia
  • Anemia
  • Anorexia
  • Back pain
  • Depression
  • Diarrhea
  • Dyspnea
  • Musculoskeletal pain
  • Nausea
  • Neutropenia
  • Pharyngitis
  • Somnolence
  • Vomiting
  • Weight loss

Always consult your healthcare provider to
ensure the information displayed on this page applies to your personal
circumstances.

Keywords: interferon alfa; interferon
alfa-2b; interferon alfa-n3.

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