Use of interferon in the treatment of chronic myelogenous leukemia.

In a series of studies spanning 14 years, investigators from M.D. Anderson Cancer Center (Houston, TX) documented the activity of interferon-alfa (IFN-alpha) in chronic myelogenous leukemia (CML). Beginning with partially purified IFN-alpha, we demonstrated that this biologic compound has clinical activity against CML, that some malignancies are resistant to IFN-alpha, and that the effect is selective whereby the malignant clone can be restored to normalcy. These observations were confirmed by us and others when larger quantities of IFN-alpha became available through recombinant DNA technology (rIFN-alpha). In contrast with our experience with chemotherapy, myelosuppression was not required for cytogenetic remission; this dissociation may be the basis for the selectivity of IFN-alpha against CML. Recently, another group demonstrated that patients randomized to receive rIFN-alpha 2a survived longer than those treated with standard hydroxyurea chemotherapy. New tests are needed to identify the subset of patients most likely to benefit from IFN-alpha therapy and to distinguish cytogenetic responders who are truly cured from those with minimal residual disease.