Pegylated Filgrastim Versus Filgrastim for Stem Cell Mobilization in Multiple Myeloma After Novel Agent Induction

The current standard of care for transplant-eligible multiple myeloma (MM) patients is novel agent-based (NA) induction followed by high-dose chemotherapy and autologous stem cell transplant (ASCT). This study analyzed the efficacy of pegfilgrastim in stem cell (PBSC) mobilization compared to filgrastim, exclusively after NA-based induction in a homogeneous group of MM patients. We analyzed 89 patients with MM treated at 2 transplant centers in Singapore who received NA-based induction chemotherapy, PBSC mobilization with vinorelbine/cyclophosphamide, high-dose melphalan conditioning and ASCT. This study demonstrates that a single dose of pegfilgrastim is comparable to filgrastim in terms of the timing and efficacy of PBSC harvest and could potentially spare the patient of 6 days of filgrastim injections. Background: The current standard of care for transplant-eligible myeloma patients is novel agent-based induction, followed by high-dose chemotherapy and autologous stem cell rescue. Chemo-mobilization of peripheral blood CD34 ⁺ stem cells (PBSCs) with pegylated filgrastim (pegfilgrastim), a sustained-duration formulation of filgrastim, has been used as an alternative to filgrastim in several studies involving heterogeneous cohorts of lymphoma and multiple myeloma (MM) patients and shown to be equivalent in PBSC yield and cost-effectiveness. The present study focused on the efficacy of pegfilgrastim in PBSC mobilization compared with filgrastim exclusively after novel agent-based induction in a homogeneous group of MM patients. Patients and Methods: We analyzed the data from 89 patients with MM treated at 2 transplant centers in Singapore who had received novel agent-based induction chemotherapy, PBSC mobilization with vinorelbine/cyclophosphamide, high-dose melphalan conditioning, and autologous stem cell rescue. Of the 89 patients, 61 were included in the pegfilgrastim group and 28 in the filgrastim group, with a similar median age and disease characteristics. PBSC harvesting was performed at a similar median time of 9.51 ± 0.84 days for both, and the peak peripheral blood CD34 ⁺ stem cell count was 19.90 × 10 ⁶ /kg for pegfilgrastim and 32.50 × 10 ⁶ /kg for filgrastim (95% confidence interval, −4.36 to 0.70 × 10 ⁶ /kg). Results: No significant difference was found in the median PBSC collection between the 2 groups (pegfilgrastim, 7.90 × 10 ⁶ /kg vs. filgrastim, 10.10 × 10 ⁶ /kg; P =.16). Conclusion: The present study has demonstrated that a single dose of pegfilgrastim is comparable to filgrastim in terms of the timing and efficacy of PBSC harvest and could potentially spare the patient 6 days of filgrastim injections. In addition, ours is the first study to compare these growth factors using vinorelbine/cyclophosphamide as mobilization chemotherapy.