Modified-CVAD Or Modified-Cbad Compared To High Dose Cyclophosphamide For Peripheral Blood Stem Cell Mobilization In Patients With Multiple Myeloma

Peripheral blood stem cell (PBSC) mobilization in patients with multiple myeloma undergoing autologous hematopoietic stem cell transplantation (auto-HCT) is commonly carried out using growth factors alone. Approximately 10-15% of patients receive chemomobilization, which assists with cytoreduction and improving the cell yield; however, an optimal regimen has not been established. Here we report our experience with three chemomobilization regimens that have been used at our center: i) cyclophosphamide alone (Cy) ii) modified cyclophosphamide, vincristine, doxorubicin, dexamethasone (mCVAD) and iii) modified cyclophosphamide, bortezomib, doxorubicin, dexamethasone (mCBAD).

This is a single-center, retrospective chart review of patients with multiple myeloma undergoing mobilization for an auto-HCT with Cy, mCVAD, or mCBAD between January 1, 2006 and September 30, 2012. A total of 120 patients were identified as initiating stem cell mobilization with Cy (n=39), mCVAD (n=66) or mCBAD (n=15) for multiple myeloma within the defined time period. For the purpose of this study, we combined mCVAD and mCBAD into one group (n=81). The primary objective of this study is to compare successful mobilization and collection (≥ 2 x 10⁶ CD34+ cells/kg collected) between high dose Cy (2-4 g/m² x1) and mCVAD (cyclophosphamide 350 mg/m² q12h x 4 days, vincristine 0.4mg continuous infusion daily x 4 days, doxorubicin 10 mg/ m² continuous infusion daily x 4 days, dexamethasone 40 mg IV daily x 4 days) + mCBAD (same as previous, except using bortezomib 1.3 mg/m² bolus x 4 days instead of vincristine). Secondary objectives include optimal mobilization (≥ 4 x 10⁶ CD34+ cells/kg), median number of leukapheresis sessions required, use of plerixafor, post-transplant time to neutrophil engraftment, disease status at day 100, time to progression, and incidence of febrile neutropenia, hospitalization, and ICU admissions with each mobilization regimen.

The groups were well-matched with regard to demographic characteristics. [Table] All 120 achieved a successful mobilization (≥ 2 x 10⁶ CD34+ cells/kg collected) and 118 achieved an optimal mobilization (≥ 4 x 10⁶ CD34+ cells/kg collected). There was no significant difference in the number of leukapheresis sessions (median 2, range 1-7) or plerixafor use (20.5% Cy vs. 8.6% mCVAD or mCBAD, p=0.08). There was no significant difference in the incidence of febrile neutropenia (10.3% Cy vs. 12.4% mCVAD or mCBAD, p=1.00), hospital admissions (18% Cy vs. 21% mCVAD or mCBAD, p=0.81), or ICU admissions (0% Cy vs. 1.2% mCVAD or mCBAD, p=1.00) between the groups. All 14 patients who had an episode of febrile neutropenia were hospitalized. One patient in the mCVAD or mCBAD group was admitted to the ICU with sepsis and renal failure, but was eventually discharged. There were no mobilization-related deaths in either study group. There was no significant difference in the time to neutrophil engraftment for the two groups (median 11 days, range 9-13). The median time to progression was 11.8 months in the Cy group and 9.1 months in the mCVAD or mCBAD group.

Cy, mCVAD or mCBAD can be used for successful PBSC mobilization in patients with multiple myeloma undergoing an auto-HCT without any unexpected toxicity. These approaches may be further evaluated in a randomized, prospective trial.

Off Label Use: Cyclophosphamide, mCVAD, and mCBAD will be discussed as mobilization regimens used for patients with multiple myeloma. Vincristine and doxorubicin do not have specific indications for use in multiple myeloma. Qazilbash:Celgene: Membership on an entity’s Board of Directors or advisory committees; Millennium: Membership on an entity’s Board of Directors or advisory committees.