High doses of natural α-interferon (α-IFN) in the treatment of multiple myeloma — A pilot study from the Myeloma Group of Central Sweden (MGCS)

α-interferon (α-IFN) is a biological response modifier with a dose-dependent activity. The present study on the treatment of patients with multiple myeloma with high doses of natural α-IFN was designed to meet this dose-dependent concept. 50 previously untreated patients with IgA and BJ myelomas and a s-Creatinine ≤ 200 μmol/l entered the study. Various treatment schedules were tested. The initial plan was to give the patients 30 × 106 U α-IFN daily. This dosage, however, gave unacceptable toxicity. Step-by-step decreasing dose schedules were given to the patients, 10 × 106 U of α-IFN daily for 7 consecutive d repeated every 3rd week was found to be the maximal tolerable dose that could be given to most patients. 36% (95% confidence levels: 22%-50%) of the patients responded: 41% of the IgA myelomas and 23% of BJ myelomas. Median time to response was 1.5 months and median response duration was 20 months. Impaired general condition and central nervous system and gastrointestinal-related toxicity were the main adverse reactions. Hematological side-effects were mild.