Phase 2 trial of intravenously administered plerixafor for stem cell mobilization in patients with multiple myeloma following lenalidomide-based initial therapy

Abstract

Initial therapy of multiple myeloma with lenalidomide-based regimens can compromise stem cell collection, which can be overcome with the addition of plerixafor. Plerixafor is typically given subcutaneously (SQ), with collection ∼11 h later for maximum yield. Intravenous administration may allow more rapid and predictable mobilization. This trial was designed to assess the efficacy and feasibility of IV plerixafor in patients receiving initial therapy with a lenalidomide-based regimen. Patients received G-CSF at 10 μg/kg/day for 4 days followed by IV plerixafor at 0.24 mg/kg/dose starting on day 5; plerixafor was administered early in the morning with apheresis 4-5 h later. Thirty-eight (97%) patients collected at least 3 × 10(6) CD34+ cells/kg within 2 days of apheresis. The median CD34+ cells/kg after 1 day of collection was 3.9 × 10(6) (range: 0.7-9.2) and after 2 days of collection was 6.99 × 10(6) (range: 1.1-16.5). There were no grade 3 or 4 non-hematological adverse events, and one patient experienced grade 4 thrombocytopenia. The most common adverse events were nausea, diarrhea and abdominal bloating. IV plerixafor is an effective strategy for mobilization with low failure rate and is well tolerated. It offers flexibility with a schedule of early-morning infusion followed by apheresis later in the day.

Figure 1

Figure shows the median number of CD34+cells collected (/kg body weight) on each day of apheresis. X-axis shows the day of apheresis and the Y-axis show the median CD34+ cells (× 10⁶)/kg. The error bars denote the interquartile range.

Figure 2

Figure shows the number of days to reach specific targets (4 × 10⁶/kg and 8 × 10⁶/kg from start of GCSF administration. X-axis shows the number of patients. The number of days from start of GCSF administration (Day 5 is the first day of plerixafor) is denoted by the color of the shaded portion.

Figure 3

Figure shows the kinetics of peripheral blood CD34+ cell counts. Data is presented from before the administration of plerixafor and from one, two and three days after the initiation of plerixafor. The error bars show interquartile range. Day 5 is the first day of plerixafor.