A phase II study of cyclophosphamide followed by PIXY321 as a means of mobilizing peripheral blood hematopoietic progenitor cells.

Fourteen patients with stage II-IV breast cancer were enrolled in a phase II study of cyclophosphamide followed by PIXY321 as a means of mobilizing peripheral blood progenitor cells (PBPC). All 14 women tolerated PIXY321 well, with the predominant toxicities being erythema at the injection site, fever, and arthralgias. A median of two aphereses yielded a mean of 1.3 x 10(8) mononuclear cells/kg, 8.9 x 10(4) colony-forming units-granulocyte/macrophage (CFU-GM)/kg, and 4.5 x 10(6) CD34+ cells/kg. All 14 patients underwent high-dose chemotherapy with PBPC support, the median day to ANC >500 cells/microliter was 10.6, and the median day to platelets >20,000 cells/microliter was 13. The day of 90th percentile platelet recovery was 15. When compared to PBPCs mobilized by cyclophosphamide followed by GM-CSF, the use of PIXY321 may confer an advantage of enhanced platelet recovery.