What is the role of interferon-alfa in the treatment of Kaposi sarcoma (KS)?

Updated: Apr 11, 2019
  • Author: Jessica Katz, MD, PhD, FACP; Chief Editor: Edwin Choy, MD, PhD  more...
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Answer

Immunomodulation with interferon-alfa has clinical activity in Kaposi sarcoma that may be mediated by its antiangiogenic, antiviral, and immunomodulatory properties. Time to clinical response is long (ie, 4-6 mo). Therefore, it should be reserved for patients who do not require a prompt clinical response. Interferon-alfa is most effective when the CD4 count is greater than 150-200/μL or when administered in conjunction with antiretroviral therapy. Combination interferon and chemotherapy has been no more effective than chemotherapy or interferon alone. 

Objective response rates have been seen in about 40% of patients. [90, 91] Responses depend on extent of disease, immunocompetence of the patient, prior treatment with chemotherapy, presence of circulating acid-labile interferon alpha, and beta-2 microglobulin levels. Response rates are about 4-fold higher in immunocompetent patients than in those with poor prognostic features.

Interferon is given by subcutaneous administration daily or 3 times weekly. Response may occur with low (1 million U/m2), intermediate (3-10 million U/m2), or high doses (50 million U/m2). 

Interferon alpha-2a and interferon alpha-2b were approved for treatment of Kaposi sarcoma in the pre-HAART era. Interferon-alfa has activity against HIV by suppressing messenger RNA translation into protein, preventing the assembly of intact viral particles. Thus, it has synergy with antiretroviral drugs. High-dose monotherapy was used then because there was little else to offer. High-dose therapy is rarely used at present; instead, interferon is typically given in doses of 4 to 18 million units, together with antiretroviral therapy. Dose-limiting toxicity is neutropenia.


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