Combination therapy with interferon-dexamethasone for newly diagnosed patients with multiple myeloma.
Alpha-interferon and dexamethasone are each effective in patients with multiple myeloma and have a combined inhibitory effect on the in vitro growth of myeloma colonies. The effect of combined therapy in newly diagnosed patients is unknown. Fifty-one consecutive patients with previously untreated multiple myeloma of low tumor mass received primary therapy with 3 million units (mu)/m2/day of interferon administered subcutaneously for 20 days and 20 mg/m2 of dexamethasone given orally each morning for 4 days beginning on days 1, 9, and 17. Courses were repeated after a rest period of 14 days. Results were compared with those of similar patients who received primary treatment with dexamethasone alone in the same dose regimen. The response rate was similar: 57% for patients treated with interferon-dexamethasone and 48% for those treated with dexamethasone alone. Remission and survival times of both groups were identical. Twenty-nine percent of patients resistant to interferon-dexamethasone and 19% of patients resistant to dexamethasone responded subsequently to either standard melphalan-prednisone or to a cyclophosphamide-vincristine-doxorubicin-dexamethasone combination. These regimens were also effective in one third of patients with disease relapse despite interferon. In this nonrandomized study of previously untreated patients with multiple myeloma, the addition of interferon in a dose of 3 mu/m2/day to dexamethasone achieved results similar to those with dexamethasone alone.