Beneficial impact of peripheral blood progenitor cells in patients with metastatic breast cancer treated with high-dose chemotherapy plus granulocyte-macrophage colony-stimulating factor. A randomized trial.

BACKGROUND

This study compared the efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or in combination with peripheral blood-derived hematopoietic progenitor cells (PBP) as support for patients receiving high-dose chemotherapy and assessed the adequacy of these strategies as alternatives to autologous bone marrow rescue.

METHODS

The authors studied patients with metastatic breast carcinoma who had a major response to conventional chemotherapy or had achieved a complete remission by surgical resection of all known metastases. They were treated with carboplatin 1500 mg/m2, etoposide 1200 mg/m2, and cyclophosphamide 5.0 g/m2. Before this high-dose chemotherapy, the patients had been randomly assigned to one of two hematopoietic support strategies: GM-CSF alone (Group 1) or GM-CSF-primed PBP and GM-CSF (Group 2). Autologous bone marrow was harvested from all patients for use only in the event of persistent pancytopenia with marrow aplasia on day 15.

RESULTS

A total of 18 patients were treated. Randomization was halted after the initial 10 patients because of the significant advantages for patients in Group 2 in comparison with those in Group 1 in regard to (1) the median number of days to absolute neutrophil count 0.5 x 10(9)/l (12 versus 21) and platelet count to 50 x 10(9)/l (13 versus 23), (2) platelet transfusions (3 versus 15.5), and (3) episodes of neutropenic sepsis (0 versus 4, respectively). One patient in Group 1 died from treatment-related complications. All patients in Group 1 required bone marrow reinfusion. No patient in Group 2 required bone marrow reinfusion, and no early mortality was observed in this group. Eight subsequent patients were treated with PBP and GM-CSF (Group 3). This group was more heavily pretreated than Groups 1 or 2 and had a slower hematologic recovery than Group 2. However, none of these patients required bone marrow reinfusion. The four patients in Group 1 that did not have early bone marrow rescue all had neutrophil counts of 0.0 on day 15. For Groups 2 and 3, the neutrophil counts on day 15 ranged from 0.3-2.1 x 10(9)/l (median, 1.9) and from 0.2-2.1 x 10(9)/l (median 0.6), respectively.

CONCLUSIONS

The use of PBP plus GM-CSF accelerated hematologic recovery after this chemotherapeutic regimen compared with GM-CSF alone; there were reduced morbidity and platelet transfusion requirements. Recovery was sufficiently rapid that PBP were an acceptable alternative to autologous bone marrow transplantation in patients receiving high-dose carboplatin, etoposide, and cyclophosphamide.