On December 15, 2008, the U. S. Food and Drug Administration approved plerixafor solution for subcutaneous injection, for use in combination with granulocyte-colony stimulating factor (G-CSF) to mobilise haematopoietic stem cells to the peripheral blood for collection and subsequent autologous transplantation in patients with non-Hodgkin’s lymphoma (NHL) and multiple myeloma (MM).

The efficacy and safety of plerixafor in combination with G-CSF in NHL and MM were evaluated in two placebo-controlled studies (Studies 1 and 2). Patients were randomised to receive either plerixafor 0.24 mg/kg or placebo each evening prior to apheresis. All patients received G-CSF 10 micrograms/kg daily for 4 days prior to the first dose of plerixafor or placebo and prior to apheresis. Results from 298 patients with NHL from study 1 and 302 patients with MM from study 2 were analysed.

In Study 1, 59% of patients with NHL who were mobilised with plerixafor and G-CSF collected > 5 X 106 CD34+ cells/kg from the peripheral blood in four or fewer apheresis sessions compared with 20% of patients who were mobilized with placebo and G-CSF (p < 0.001). The median number of days to reach > 5 x 106 CD34+ cells/kg was 3 days for the plerixafor group and not evaluable for the placebo group.

In Study 2, 72% of patients with MM who were mobilised with plerixafor and G-CSF collected > 6 X 106 CD34+ cells/kg from the peripheral blood in two or fewer apheresis sessions compared with 34% of patients who were mobilized with placebo and G-CSF (p <0.001). The median number of days to reach > 6 x 106 CD34+ cells/kg was 1 day for the plerixafor group and 4 days for the placebo group.

Safety data for plerixafor in combination with G-CSF were obtained from 983 patients enrolled in 16 clinical studies (593 patients enrolled in randomised Studies 1 and 2 plus 410 patients enrolled in 14 additional non-randomised studies). Patients were primarily treated with plerixafor at daily doses of 0.24 mg/kg SC. Median exposure to plerixafor was 2 days (range 1 to 7 days). The most common adverse reactions (> 10%) reported in patients who received plerixafor in conjunction with G-CSF that were more frequent than in patients who received placebo were diarrhea, nausea, fatigue, injection site reactions, headache, arthralgia, dizziness and vomiting. Prescribing physicians and patients should be aware of the potential for tumour cell mobilisation in leukaemia patients, increased circulating leukocytes and decreased platelet counts, splenic enlargement, and fetal harm when administered to pregnant women.