Background: 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.
Methods: 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.
Results: 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.
Conclusion: 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.