Interferon alfa-2b (IntronA)

How is the drug name pronounced?

Interferon alfa 2b: In-ter-FEE-ron AL-fah two-bee

IntronA: In-tron “A”

What cancer(s) does this drug treat?

IntronA is approved for:

Hairy cell leukemia
Follicular lymphoma

Hairy cell leukemia

IntronA is approved for:

  • Adult patients with hairy cell leukemia.

Follicular lymphoma

IntronA is approved for:

  • Adult patients with high tumor burden follicular lymphoma. High tumor burden refers to cancer that has begun to obstruct or interrupt organ function, that has an enlarged primary tumor site, or that has spread to multiple secondary tumor sites. In such cases, IntronA is administered in combination with chemotherapy.


IntronA is approved for:

  • Adult patients with melanoma, within 56 days of surgical removal of all known disease, who are at high risk of the cancer returning and affecting other organs.

Limitations of Use

Age: The safety and efficacy of IntronA in patients under 18 years of age have not been established.
Hypersensitivity: IntronA should not be used in patients who are allergic or hypersensitive to IntronA or any of its components.
Caution: IntronA should be used cautiously in patients with a history of lung disease (e.g., chronic obstructive pulmonary disease), diabetes prone to ketoacidosis, blood coagulation disorders (e.g., thrombophlebitis, pulmonary embolism), heart disease, or severely reduced bone marrow activity and production of blood cells.
Mental health problems: IntronA should be used with caution in patients who have a history of mental health problems.
Interaction with other drugs: Concomitant therapy with xanthine agents (e.g., theophylline or aminophylline) must be administered with caution, and dose adjustment may become necessary. Administration of IntronA in combination with chemotherapeutic agents (e.g., Ara-C, cyclophosphamide, doxorubicin, teniposide) may lead to more severe and prolonged side effects.
Fertility/Pregnancy/Breastfeeding: IntronA may impair fertility in women. IntronA may cause harm to a fetus, and is not recommended for use during pregnancy. Women and men should use contraception during treatment with IntronA. The risks associated with Sylatron during breastfeeding are not known and cannot be ruled out. Due to the potential for adverse reactions in the breastfed child, the benefits of breastfeeding and the mother’s need for treatment should be weighed accordingly before moving forward with treatment IntronA.

What type of immunotherapy is this?

Cytokine therapy

  • Interferon therapy

How does this drug work?

  • Target: Type I interferon receptors (IFNAR1/2)

IntronA is a protein that is a laboratory-made version of interferon alfa-2b (IFNalpha-2b) – a type of protein called an interferon – which is naturally produced in the body. Interferons are an important part of “cell signaling”, which is when different cells in the body “talk” to one another using chemical signals. IntronA binds to type I interferon receptors, found on the surface of many different types of cells, including immune cells and cancer cells. The exact mechanism by which IntronA helps fight cancer is not known. It is thought to activate one or more parts of the immune system in its fight against cancerous cells, to directly induce death in cancer cells, or to work in both ways.

How is this drug given to the patient?

IntronA is administered either via an injection beneath the skin (subcutaneous injection) or via a tube in the vein (intravenous infusion, or i.v.), depending on the patient’s diagnosis. The dosage and treatment schedule also varies depending on the patient’s diagnosis. Treatment with IntronA may be interrupted or the dosage may be modified if the patient experiences any negative reactions during treatment. If the patient experiences persistent intolerance to the treatment, or if their cancer continues to progress, treatment may be permanently discontinued.

Hairy cell leukemia: IntronA is administered via an injection beneath the skin every other day (three times a week) for up to 6 months. The treatment may be continued for patients who show a response to treatment.

Follicular lymphoma: IntronA is administered via an injection beneath the skin every other day (three times a week) over 18 months, in combination with chemotherapy. Thereafter, IntronA treatment may be continued.

Melanoma: IntronA is administered via a tube in the vein over 20 minutes daily, for 5 consecutive days per week, for 4 weeks. Thereafter, IntronA is administered as maintenance therapy via an injection beneath the skin every other day (three times a week) for 48 weeks, to prevent the cancer from getting worse or coming back.

What are the observed clinical results?


Hairy cell leukemia
Follicular lymphoma

It is important to keep in mind that each patient’s actual outcome is individual and may be different from the results found in the clinical studies. In addition, with immunotherapy, sometimes it takes several months for responses to be observed.

Hairy cell leukemia

In a clinical study, patients with hairy cell leukaemia were treated with IntronA. 75% of patients responded to treatment with sustained improvements in blood test results (normalization of granulocytes, platelets, and hemoglobin levels) and at least some improvement occurred in 90% of the patients.

After 12 months of initial IntronA therapy, 126 patients who showed a response to treatment were treated with IntronA doses for 6 months, or were observed with no further treatment. During this 6-month period, 3% of IntronA-treated patients experienced worsening of their disease compared with 18% of those who were not treated.

Follicular lymphoma

In a clinical study, 265 patients with high tumor burden follicular lymphoma were either treated with CHVP (cyclophosphamide, doxorubicin, teniposide, and prednisone) chemotherapy or CHVP chemotherapy and IntronA. Patients treated with CHVP chemotherapy and IntronA did not experience worsening of their disease for a median of 3 years and lived for a median of 7 years, compared to patients treated with CHVP chemotherapy alone, who experienced worsening of their disease at a median of 1.5 years and lived for a median of 5 years.


In a clinical study, 280 patients with melanoma whose tumor had been surgically removed were either treated with IntronA following surgery or observed with no further treatment. Patients treated with IntronA did not experience worsening of their disease for a median of 21 months and lived for a median of 46 months, compared to patients in the observation group alone, who experienced worsening of their disease at a median of 12 months and lived for a median of 33 months.

What are the potential side effects?

The most common side effects of IntronA include fatigue, flu-like symptoms (including fever, headache, tiredness, muscle or joint aches, and chills), infections, nausea, loss of appetite, feeling sad or depressed, redness, swelling, or itching around the injection site, hair thinning, low blood cell counts, and changes in blood tests that measure how well the liver works.

IntronA can cause side effects that can become serious or life-threatening, and may lead to death. Some of the serious side effects related to IntronA include problems with the heart, lungs, brain (altered level of consciousness, stroke), eyes, thyroid, or liver (including liver failure); diabetes; allergic reactions; infections; inflammation of the pancreas or intestines; new or worsening autoimmune disease; and mental health problems.

Serious mental health problems

IntronA can cause serious mental health problems, such as depression, which can lead to suicide. IntronA can also increase the risk of relapse in patients recovering from drug addiction. Such reactions may occur up to 6 months after the last treatment with IntronA. Some of the symptoms of serious mental health problems include irritability, depression, aggressive behavior, and thoughts of hurting oneself or others.

New or worsening autoimmune disease

IntronA may cause the onset of autoimmune diseases (a condition where the body's immune cells attack healthy cells or organs in the body), including rheumatoid arthritis, systemic lupus erythematosus, sarcoidosis, and psoriasis. In some people who already have an autoimmune disease, the disease may get worse during treatment with IntronA.

Patients should report any symptoms to their healthcare provider, who can then initiate actions to limit or reverse the side effects. For a more complete list of possible side effects, see the full prescribing information.

Additional Information


Merck Sharp & Dohme



Other references:

Last updated on May 4, 2021

Understanding Cancer Immunotherapy Research