Low-dose or intermediate-dose cyclophosphamide plus granulocyte colony-stimulating factor for progenitor cell mobilisation in patients with multiple myeloma.

Cyclophosphamide (CY) combined with granulocyte colony-stimulating factor (G-CSF) is commonly used to mobilise blood progenitor cells to support high-dose therapy in patients with multiple myeloma (MM). The optimal dose of CY in this setting is unknown. We have retrospectively analysed mobilisation efficiency and need for supportive care in 57 patients with newly diagnosed myeloma previously treated with VAD+/-local radiotherapy. The patients were mobilised either with low-dose CY (LD-CY, 1.2-2 g/m(2)) (n=25) or intermediate-dose CY (ID-CY, 4 g/m(2)) (n=32) plus G-CSF. Both regimens proved to be effective in the progenitor cell mobilisation. At least 2 x 10(6)/kg CD34+ cells were collected from 88% and 84% of the patients with a single apheresis, respectively. Only one patient in the LD-CY group (4%) failed to mobilise vs none in the ID-CY group. Patients mobilised with LD-CY plus G-CSF had less toxicity: fewer hospital days during the mobilisation and apheresis procedures (5 vs 9 days, P<0.001), lower frequency of fever (20 vs 73%, P<0.001) and less need for supportive care including platelet transfusions (0 vs 24%, P=0.004) and days on parenteral antibiotics (0 vs 4 days, P<0.001). While these regimens seem to be equally effective in terms of progenitor cell mobilisation in newly diagnosed patients with MM, LD-CY+G-CSF is preferential because of more optimal resource utilisation and more favourable toxicity profile.