Peripheral blood progenitor cell mobilisation in patients with multiple myeloma following oral idarubicin and dexamethasone (Z-Dex) induction therapy.

Difficulties associated with current intensive induction regimens for multiple myeloma and uncertainty as to how to achieve optimal peripheral blood progenitor cell mobilisation (PBPC) prompted this study of an oral induction regimen, Z-Dex (oral idarubicin and dexamethasone) followed by PBPC mobilisation using four different regimens. Thirty-patients received Z-Dex (median age 56 years, range 46-66 years) including 24 patients with previously untreated disease. The overall response rate was 75% with a CR rate of 16.7% and PR rate of 75.7% in patients with previously untreated disease. We compared four mobilisation regimens: low-dose (LD) cyclophosphamide, high-dose (HD) cyclophosphamide, cis-platin/VP16 and cis-platin, Ara-C and dexamethasone (DHAP). Failure to mobilise optimal numbers of PBPCs (>1.0 x 10(6) CD34+ cells/kg and >20 x 10(4) CFU-GM/kg) was seen in two patients who received LD cyclophosphamide, in two patients who received HD cyclophosphamide and three patients who received cis-platin/VP16. No patient failed to mobilise adequate numbers of PBPCs following DHAP. In previously untreated patients, DHAP mobilised significantly more PBPC than LD cyclophosphamide (P=0.02), HD cyclophosphamide (P=0.0015) and cis-platin/VP16 (P=0.021). This study demonstrates the efficacy of Z-Dex in inducing tumour responses in patients with multiple myeloma without limiting PBPC mobilisation in subsequent dose-intensive schedules. Furthermore, we also demonstrate that DHAP is superior to cyclophosphamide (low- and high-dose) and cis-platin/VP16 in mobilising PBPCs and demonstrated a degree of tumour control.