Recombinant human thrombopoietin augments mobilization of peripheral blood progenitor cells for autologous transplantation

Abstract

This study assessed the ability of various schedules of recombinant human thrombopoietin (rhTPO) to enhance mobilization of peripheral blood progenitor cells (PBPCs) in 134 patients with cancer undergoing high-dose chemotherapy and autologous PBPC transplantation. Patients received the study drug on days 1, 3, and 5 before initiation of granulocyte colony-stimulating factor (G-CSF) 10 μg/kg/day on day 5 and pheresis starting on day 9. Randomly assigned treatments on days 1, 3, and 5 were: group 1 (n=27) placebo, placebo, rhTPO 1.5 μg/kg; group 2 (n=27) rhTPO 1.5 μg/kg, placebo, placebo; groups 3 (n=28) and 4 (n=22) rhTPO 0.5 μg/kg on all 3 treatment days; and group 5 (n=30) placebo on all 3 treatment days. After high-dose chemotherapy and PBPC transplantation, groups 1 through 4 received rhTPO 1.5 μg/kg days 0, +2, +4, and +6 with either G-CSF 5 μg/kg/day (groups 1-3) or granulocyte-macrophage colony-stimulating factor 250 μg/m 2/day (group 4). Group 5 received placebo plus G-CSF 5 μg/kg/day. The addition of rhTPO to G-CSF increased median CD34 + cell yield/pheresis in cohorts in which rhTPO was started before day 5, with higher yields in groups 2 (2.67 × 10 6/kg) and groups 3 and 4 (3.10 × 10 6/kg) than in group 1 (1.86 × 10 6/kg) or group 5 (1.65 × 10 6/kg) ( P=.006 across groups). Comparing rhTPO to placebo, higher percentages of patients achieved the minimum yield of CD34 + ≥2 × 10 6/kg (92% v 75%; P=.050) as well as the target yield of CD34 + ≥5 × 10 6/kg (73% v 46%; P=.041). rhTPO-treated patients required fewer phereses to achieve minimum ( P=.011) and target ( P=.015) CD34 + cell values. rhTPO given after transplantation did not speed platelet recovery. No neutralizing antibodies were observed. We conclude that rhTPO can safely enhance mobilization of PBPC, reduce the number of leukapheresis, and allow more patients to meet minimal cell yield requirements to receive high-dose chemotherapy with PBPC transplantation.