Treatment with Plerixafor in non-Hodgkin's Lymphoma and Multiple Myeloma Patients to Increase the Number of Peripheral Blood Stem Cells When Given a Mobilizing Regimen of G-CSF: Implications for the Heavily Pretreated Patient

We investigated the efficacy and toxicity of combining granulocyte-colony stimulating factor (G-CSF) at standard doses with plerixafor, a CXCR4 inhibitor, to mobilize stem cells in patients with non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM). Patients with NHL and MM underwent mobilization with G-CSF (10 μg/kg/day) for up to 9 days and plerixafor (240 μg/kg/day), which started on the evening of day 4. Apheresis began on day 5 and continued daily until either ≥5 × 10⁶ CD34/kg were collected or to a maximum of 5 aphereses. Toxicities, increase in circulating CD34 cells/μL before and after the first dose of plerixafor, percentage of patients collecting ≥5 × 10⁶ CD34/kg, total CD34 cells/kg collected, engraftment, and exploratory efficacy analyses in heavily pretreated patients were examined. Six sites enrolled 49 patients (NHL, 23; MM, 26). All completed mobilization and 47 of 49 (96%) underwent transplant. Circulating CD34 cells/μL increased by 2.5-fold (1.3-6.0-fold) after the first plerixafor dose. The median CD34 cells/kg collected was 5.9 × 10⁶ (1.5-22.5) in 2 (1-5) days of aphereses. Median days to neutrophil and platelet engraftment were 11 (8-16) and 14.5 (7-39) days, respectively. Adverse events primarily were mild nausea and diarrhea (n = 24). Twenty-eight (57%) were identified as heavily pretreated patients. Their median fold increase in circulating CD34 cells/μL was 2.5 (1.4-5.0) after plerixafor, similar to minimally pretreated patients. Plerixafor and G-CSF increased circulating CD34 cells/μL and led to the adequate collection of stem cells for autotransplant in 96% of the patients. This combination may have particular value in heavily pretreated patients.