Interferon in the Treatment of Refractory Multiple Myeloma: An Eastern Cooperative Oncology Group Study.

Twenty-three patients with relapsed or refractory multiple myeloma were treated with recombinant alpha-2 interferon (rIFNα2b) administered subcutaneously at a dose of 10 × 10(6) IU/m(2) 3x/week for 12 weeks. Of the 20 evaluable patients 12 had received two or more prior chemotherapy regimens and nine had failed to respond to all prior treatment. Two patients had an objective response (OR) to rIFNα2b manifest by >50% decrease in M-protein or extramedullary plasmacytomas. Three other patients had objective improvement (I) with 25-50% decrease in M-protein and marked decrease in bone pain (OR + I = 25%). Two other patients had disease stabilization and freedom from symptoms for more than one year. Four of 13 patients with moderate-to-severe bone pain had marked pain reduction for 4-48 months. All patients had the flu-like syndrome associated with initial doses of interferon. Three had dose-limiting fatigue. Six patients had severe neutropenia <1000/mcl and six had platelets <50 000/mcl. Chronic dose modification was required in 75% of patients. The maximum tolerated dose in most patients was 5 × 10(6) IU/m(2). This study demonstrates that rIFNα2b is active in late multiple myeloma, producing clinical benefit in a third of patients. Since myelotoxicity was mild and transient when the 5 × 10(6) IU/m(2) dose level was used, interferon should be considered a potentially useful treatment option in this marrow-impaired group of patients.