High-Dose Cyclophosphamide + G-CSF Mobilization Regimen Have Higher Anti-Myeloma Effects Than G-CSF Alone Regimen – Single Institutional Study in 147 Myeloma Patients From Japan

Abstract 2007 Background: High-dose cyclophosphamide (HD-CY) + granulocyte-colony stimulating factor (G-CSF) and G-CSF alone have been used to mobilize hematopoietic stem cells (HSCs) for autologous SC transplantation (ASCT) in multiple myeloma (MM). However, which regimen is better is unknown; anti-myeloma effects of HD-CY + G-CSF have not been established. From January 1999 to June 2009, we administered HD-CY+G-CSF but changed to G-CSF alone during July 2009–December 2010. We retrospectively assessed HSC collection efficacy, complications, and anti-myeloma effects of these regimens. Patients and methods: We analyzed 147 MM patients from whom HSCs were to be collected at our institute. For mobilization, 115 patients were administered HD-CY (4 g/m 2 )+G-CSF (600 mg/body filgrastim or 500 mg/body lenograstim) and 32 were administered G-CSF alone (same dose as HD-CY). Here, 17 patients received therapeutic intervention between mobilization and transplantation without disease progression (PD). To avoid the patient outcome effect, we defined event- and progression-free survivals (EFS and PFS). EFS was defined as PD, death, or therapeutic intervention without PD. PFS was defined as PD or death, where therapeutic intervention without PD was used as a censor. Both were calculated from the start of mobilization. For analyzing response by mobilization, patients receiving therapeutic intervention without PD were excluded. Response was evaluated in those not receiving therapeutic intervention without PD or in whom response could not be evaluated before ASCT. Thalidomide was administered as maintenance therapy to 14 and 6 patients in the HD-CY+G-CSF and G-CSF groups after ASCT. Thalidomide administration was used as a censor. Results: Vincristine, doxorubicin, and dexamethasone (VAD) and HD dexamethasone (HDD) therapies were administered as induction therapy (VAD for 117, HDD for 2, and both for 11). New (bortezomib or thalidomide) and alkylating agents were administered to 7 and 13 patients, respectively. Before mobilization, 26 patients received radiotherapy; none were administered lenalidomide. No statistical difference was seen in baseline characteristics (Durie-Salmon stage, International staging system, interval from diagnosis to mobilization, disease control, and previous therapies) between both groups. However, patients mobilized by G-CSF alone were significantly older. Among 147 patients, 121 underwent planned ASCT. Of the 17 receiving therapeutic intervention without PD, 13 and 4 belonged to the HD-CY+G-CSF and G-CSF groups, respectively. More than 2 × 10 6 CD34-positive cells/kg were collected from 93% and 75% patients in the HD-CY+G-CSF and G-CSF (p = 0.0079) groups, respectively. More than 4 × 10 6 CD34-positive cells/kg were collected from 84% and 69% in the HD-CY+G-CSF and G-CSF (p = 0.07). Mean HSC count was 11.4 × 10 6 /kg in the HD-CY+G-CSF group and 4.5 × 10 6 /kg in the G-CSF group (p = 0.0007). Among patients receiving HD-CY+G-CSF, 66% were treated with intravenous antibiotics; 3 suffered cardiac shock and 2 septic shock. However, among those receiving G-CSF alone, no severe complications were seen. Median hospitalization days were 21 and 8 for the HD-CY+G-CSF and G-CSF groups, respectively (p In the HD-CY+G-CSF group, 16% improved in disease control before ASCT, 71% showed no change, and 13% progressed. However, no patient improved, 63% showed no change, and 27% progressed in the G-CSF group (p = 0.015). Median EFS was 25 months in the HD-CY+G-CSF group and 13 in the G-CSF group (fig 1, p value of log-rank test = 0.012). Median PFS was 28 months in the HD-CY+G-CSF group and 15 in the G-CSF group (fig 2, p value of log-rank test = 0.011). Median overall survival did not differ significantly. Conclusion: Regarding the safety and duration of hospitalization, G-CSF alone may be safer and beneficial. However, HD-CY+G-CSF was more effective as a mobilization regimen and showed higher anti-myeloma effects than G-CSF alone. Disclosures: No relevant conflicts of interest to declare.