Interferons in the treatment of multiple myeloma

A review of the clinical studies in which interferons have been involved has shown that they may have a role in the treatment of multiple myeloma. Twelve studies, each of which involved at least 10 evaluable cases (352 in total) with various dose schedules involving leukocyte, lymphoblastoid and recombinant alpha-IFNs, reported 8-33% objective responses. The response duration was rather short but, in a few cases, it lasted for more than a year. In addition to a decrease in the levels of M-protein and/or urine Bence-Jones protein, a decrease in the number of plasma cells in the bone marrow, disappearance of bone pain, healing of bone lesions, increase of hemoglobin and/or restoration of normal immunoglobulins were observed. Higher doses of recombinant alpha-interferons seemed to exert a stronger effect. No clear difference in response rate was observed between myeloma which had been previously treated and that which was not treated. At least clinically, therefore, there seems to be no cross-resistance between alpha-interferons and conventional anti-tumor drugs. A randomized study comparing low-dose leukocyte interferon with intermittent high-dose melphalan-prednisone has given a lower response rate for interferon. Beta- and gamma-interferons have not yet been extensively studied. They have been used at low doses producing an objective response in 7% of 68 and 2% of 45 evaluable cases, respectively. Since the myelosuppression of interferons is transient and, after discontinuation of interferon therapy, peripheral blood cells usually recover within a week, it may be possible to use interferon in combination with agents that have strong myelosuppressive effects provided there is no synergism.