Background: In myeloma patients resistance to both melphalan- and doxorubicin-containing regimens has been related to very short survival (approximately 6 months). The development of effective regimens combined with a low toxicity rate is mandatory in this patient subgroup.
Methods: Fourteen resistant myeloma patients were treated with cyclophosphamide (a total of 3.6 g/m2 was delivered in 2 doses on days 1 and 3) and prednisone (2 mg/kg, days 1-4) every month for 4 cycles. G-CSF support was administered to reduce myelosuppression.
Results: This combination was well tolerated. Granulocyte levels fell below 0.1 x 10(9)/L in all patients after a median of 9 days (range 8-11), followed by recovery to 0.5 x 10(9)/L after a median of 12 days from the start of treatment (range 10-13 days). Platelets never fell below 50 x 10(9)/L. All patients were treated on an outpatient basis and only 2 required hospitalization for major complications (pneumonia and heart failure). Response to cyclophosphamide was observed in 6/14 patients: 2 achieved complete remission, 4 showed a 50% or greater reduction of the M-component. Five patients are still in remission after 2, 6, 7, 9 and 10 months; 1 relapsed after 10 months. All patients except one are alive 4-16 months from the start of treatment.
Conclusions: This schedule may represent a new approach for resistant myeloma, and its very low toxicity allows it to be delivered on an outpatient basis.