Peripheral blood stem cell mobilization, which is important as a source of hematopoietic stem cells for transplantation, is generally performed using granulocyte colony-stimulating factor (G-CSF), but is ineffective in around 15 to 20% of patients. Combination of G-CSF with plerixafor increases the percentage of persons that respond to the therapy and produce enough stem cells for transplantation.[1] The drug is approved for patients with lymphoma and multiple myeloma.[2]