In the two phase III randomized trials, 298 patients with NHLr and 302 with MMr were recruited. In the NHL group, the primary end point (>5 x 106 CD34+ cells/kg) was reached in 59% of the plerixafor-treated patients and 20% of those who received placebo (P<0.001). In the plerixafor group, 86.7% obtained at least 2 x 106 CD34+ cells/kg, compared to 47.3% in the placebo group, which is considered the minimum requirement to safely proceed to autologous transplant (P<0.001).
Results were similar in the MM study, where the primary end point (>6 x 106 CD34+ cells/kg) was reached in 71.6% in the plerixafor group and 34.4% in the placebo group (P<0.001). Comparing between groups for the achievement of at least 2 x 106 CD34+ cells/kg, this was also higher in patients given plerixafor at 95.3% versus 88.3% (P=.031). Fifty-four percent of patients met the primary endpoint after one apheresis following plerixafor, while 56% of patients receiving placebo required four apheresis sessions to reach this target.
Subsequently, the results of compassionate access studies from Europe and the US have shown the efficacy of plerixafor in patients who had failed mobilisation and were therefore not eligible for the registration trials.rrrr Using the same combined G-CSF and plerixafor protocol, between 40-75% of patients were able to achieve collection of at least 2 x106/kg CD34+ cells.
||Achieved >2x106 CD34+ cells/kg
||Phase III: NHL first mobilisation
||Phase III: Myeloma first mobilisation
US compassionate use data for failed mobilisation
EU compassionate use data for failed mobilisation
||Salvage in patients with failed mobilisation from Phase III NHL trial (DiPersio2)
||Prior plerixafor: 11
Prior placebo: 57
||EU compassionate use data for failed mobilisation after previous fludarabine or lenalidomide
||Prior fludarabine: 48
Prior lenalidomide: 35
Plerixafor has also been used in a pre-emptive or ‘on demand’ fashion to increase the likelihood of patients at risk of failing stem cell mobilisation using chemotherapy and/or G-CSF.rrrr With these strategies 13/16 (81%),r 33/34 (97%)r and 98/102(96%)r of patients were able to meet cell collection targets.