Antibodies to interferon-alpha in treated cancer patients: incidence and significance.

Antibodies to interferon-alpha (IFN-alpha) are found in some patients being treated with this cytokine. In studies in which two recombinant IFN-alpha preparations were directly compared in cancer patients, those given IFN-alpha2a were found to have neutralizing antibodies in their serum significantly more often than those given IFN-alpha2b (p <0.001). Patients who develop neutralizing antibodies are more likely to have a clinical relapse and to become resistant to further treatment with at least the IFN preparation initially used for their treatment. In 10 studies in cancer patients, such an outcome was found in 63% of those who developed antibodies but in only 13% of those who did not. These data are tabulated.