A randomized comparison of etoposide and cyclophosphamide for stem cell mobilization in newly diagnosed multiple myeloma

Abstract Successful autologous stem cell transplantation (ASCT) in newly diagnosed multiple myeloma (NDMM) patients relies on the efficient mobilization of hematopoietic stem cells following induction therapy. While the efficacy of etoposide for stem cell mobilization has been demonstrated in numerous studies, a randomized comparison of the efficacy of cyclophosphamide versus etoposide has previously been lacking. This randomized, open-label, multicenter trial enrolled NDMM patients eligible for ASCT. The inclusion criteria were patients with a diagnosis of NDMM who required stem cell mobilization prior to ASCT. Patients were randomly assigned to receive either high-dose etoposide (VP16; 1.2 g/m 2 ) or high-dose cyclophosphamide (CTX; 3.0 g/m 2 ) before mobilization. Granulocyte colony-stimulating factor (G-CSF) was administered after chemotherapy to promote stem cell mobilization. The primary endpoint was the proportion of patients achieving CD34 + cell counts ≥ 2 × 10⁶/kg and ≥ 5 × 10⁶/kg. A total of 62 patients were enrolled, with 31 patients in each group. The VP16 group significantly outperformed the CTX group in CD34 + cell collection across all thresholds: ≥2 × 10⁶/kg (100% vs. 77%, p = 0.011), ≥ 5 × 10⁶/kg (90% vs. 55%, p = 0.002), and ≥ 8 × 10⁶/kg (71% vs. 32.3%, p = 0.023). The VP16 group also showed superior success rates in the first apheresis session and achieved higher CD34 + percentages in the collection. Additionally, the VP16 group required fewer apheresis sessions, fewer platelet transfusions, and experienced less nausea during the mobilization period. High-dose etoposide (1.2 g/m 2 ) demonstrated superior efficacy and safety compared to high-dose cyclophosphamide (3.0 g/m 2 ) for stem cell mobilization in NDMM patients. Based on these findings, etoposide may be considered a more effective and safer option for stem cell mobilization in clinical practice. The clinical trial was registered on 24/08/2022 (clinical trial identifier NCT05517213).