Cyclophosphamide–Bortezomib–Dexamethasone Compared with Bortezomib–Dexamethasone in Transplantation-Eligible Patients with Newly Diagnosed Multiple Myeloma

Introduction: Cyclophosphamide–bortezomib–dexamethasone (CyBorD) is considered a standard induction regimen for transplant-eligible patients with newly diagnosed multiple myeloma (MM). It has not been prospectively compared with bortezomib–dexamethasone (Bor-Dex). We aimed to compare the efficacy of CyBorD and Bor-Dex induction in transplant-eligible patients. Methods: In a retrospective observational study at a single tertiary centre, all patients with transplant-eligible MM who received induction with CyBorD or Bor-Dex between March 2008 and April 2016 were enrolled. Progression-free survival (PFS), response, and stem-cell collection for a first autologous stem-cell transplantation (aHSCT) were compared. Results: Of 155 patients enrolled, 78 (50.3%) had received CyBorD, and 77 (49.7%), Bor-Dex. The patients in the Bor-Dex cohort were younger than those in the CyBorD cohort (median: 57 years vs. 62 years; p = 0.0002) and more likely to have had treatment held, reduced, or discontinued (26% vs. 14.5%, p = 0.11). The stem-cell mobilization regimen for both cohorts was predominantly cyclophosphamide and granulocyte colony–stimulating factor (GCSF). Plerixafor was used more often for the CyBorD cohort (p = 0.009), and more collection failures occurred in the CyBorD cohort (p = 0.08). In patients receiving Bor-Dex, more cells were collected (9.9 × 10⁶ cells/kg vs. 7.7 × 10⁶ cells/kg, p = 0.007). At day +100, a very good partial response or better was achieved in 75% of the CyBorD cohort and in 73% of the Bor-Dex cohort (p = 0.77). Median PFS was 3.2 years in the Bor-Dex cohort and 3.7 years in the CyBorD cohort (p = 0.56). Conclusions: Overall efficacy was similar in our patients receiving CyBorD and Bor-Dex. After aHSCT, no difference in depth of response or PFS was observed. Cyclophosphamide–GCSF seems to increase collection failures and hospitalizations in patients receiving CyBorD. Prospective studies are required to examine that relationship.