Comparison of Progenitor Cell Collection on Day 4 or Day 5 After Steady-State Stimulation with G-CSF Alone in Breast Cancer Patients: Influence on CD34 + Cell Yield,Subpopulation,and Breast Cancer Cell Contamination

Abstract

To determine the influence of apheresis timing on CD34⁺ cell yield, subpopulation, and breast cancer cell contamination, 48 women with breast cancer were stimulated from steady-state hematopoiesis in a prospective but nonrandomized study with 2 X 5 mug/kg G-CSF s.c. alone, and apheresis was started either on day 4 (n = 24) or day 5 (n = 24). Forty-eight women with breast cancer(stage II/III, n = 30; stage IV; n = 12; inflammatory, n = 6) and a median age of 44 years were well balanced between the two groups. In group I, aphersis was started on day 4 and additionally performed on day 5 after G-CSF stimulation, and in group II, apheresis was started on day 5. CD34⁺ cell count and CD34⁺ cell subpopulation were determined according to international criteria. Breast cancer cell contamination was detected by immunocytology. The median CD34⁺ cell harvest on day 4 was 3.3 X 10⁶/kg body weight (range 0.5-12.8) and 6 X 10⁶/kg BW (range 0.3-30) for patients starting on day 5 (p = 0.01). Those patients starting on day 4 achieved a median CD34⁺ cell count of 4 X 10⁶/kg (range 0.7-13) on day 5 (NS). Twenty-one percent of group I and 71% of group II achieved >5 X 10⁶/kg BW CD34⁺ cells in the first apheresis, whereas <2.5 X 10⁶/kg BW CD34⁺ cells in the first apheresis were observed in 38% of group I and 16% of group II. No differences were observed between the CD34⁺ cell subpopulations, CD34⁺/CD38⁺ (10.5% versus 10.5%) and CD34⁺/Thy1⁺ (1.5% versus 1.8%). The CD34⁺ cell harvest from consecutive collecting on days 4 and 5 was nearly identical to the harvest starting on day 5 (6.4 versus 6 X 10⁶/kg). Collecting CD34⁺ progenitor cells after stimulation with G-CSF alone on day 5 results in a significantly higher cell yield than starting collecting on day 4. No differences in respect to breast cancer cell contamination and CD34⁺ cell subpopulation were observed.