Application of whole blood and peripheral blood progenitor cells (PBPC) and new strategies for rescue after intensive cyclic chemotherapy in high-risk breast cancer

The efficacy of autologous peripheral stem cells given as mobilized whole blood or leukapheresis product for hematopoietic rescue after intensive chemotherapy was studied in 34 consecutive female patients with high-risk breast cancer. All patients received six cycles of chemotherapy regimen EC (epirubicin 150 mg/m2 and cyclophosphamide 1250 mg/m2) at 14-day intervals. In the first cycle, chemotherapy was given on day 1, and 24 h later mobilization of PBPC was started with G-CSF at a dose of 5 microg/kg/day for 13 days. In all other cycles, G-CSF was given at the same dose from day 7. On days 11, 12, and 13, leukaphereses were performed, and whole blood was collected on day 14 (the peak incidence of colony-forming units-granulocyte-macrophage [CFU-GM] burst-forming units-erythrocyte [BFU-E], and colony-forming unit-granulocyte-erythrocyte-macrophage-megakaryocyte [CFU-GEMM]). The second cycle of chemotherapy was started on day 15, and 24 h later, whole blood (collected in the first cycle) was reinfused, and the same was done in the third cycle. In the fourth to sixth chemotherapy cycles, leukapheresis product was used for hematopoietic rescue. The median increment of absolute values in both whole blood and leukapheresis product was as follows: CD34+ cells over baseline was approximately 17.4-fold, CFU-GM was 85.3-fold, BFU-E was 95.9-fold, and CFU-GEMM was 44.2-fold. In the cycles with whole blood support, the mean values of applied progenitors per cycle were CD34+ cells 1.52 x 10(6)/kg, CFU-GM, 1.18 x 10(5)/kg, BFU-E 2.54 x 10(5)/kg, CFU-GEMM 0.31 x 10(5)/kg. In the courses with PBPC support, the mean values of progenitors were CD34+ 2.04 x 10(6)/kg, CFU-GM 1.59 x 10(5)/kg, BFU-E 2.87 x 10(5)/kg, and CFU-GEMM 0.34 x 10(5)/kg. Leukopenia in patients supported with whole blood versus leukapheresed PBPC was as follows: grade 4, 13/6 (38.2%/17.6%), grade 3, 19/23 (55.9%/70.6%), and grade 2, 1/4 (2.9%/11.8%), respectively. Thrombocytopenia was grade 4, 11/6 (32.4%/17.6%), grade 3, 10/7 (29.4%/20.6%), grade 2, 7/13 (20.6%/38.2%), and grade 1, 6/6 (17.6%/17.6%), respectively. The median follow-up analysis was at 24.6 (7-36) months. High-risk patients previously treated with surgery and adjuvant chemotherapy (n = 5) were not evaluated for response. In 21 patients with locally advanced or inflammatory breast carcinoma the response rate (RR) was 94%, CR was 90%, and PR was 15%. No response to therapy was observed in 1 patient. In 8 patients with metastatic disease, RR was 75%, there was no CR, and PR was 75%. Two patients died during therapy. Relapse-free survival (RFS) in the adjuvant group was 23.7 (range 12-36) months and in the group with locally advanced disease was 18.2 (range 7-27) months. In the group with metastatic disease, time to tumor progression (TTP) was 12.1 (range 1-16) months. Mean duration of hospital stay for whole blood reinfusion in the second and third chemotherapy cycles was 6.7 (range 5-8) days and for PBPC in the fourth to sixth cycles was 6.2 (range 4-8) days, which at p < 0.001 was not statistically significant.

Thrombocytopenia after high-dose chemotherapy and autologous stem cell transplantation: an unresolved problem and possible approaches to resolve it

Prolonged thrombocytopenia is a frequent clinical problem in cancer patients undergoing high-dose chemotherapy and autologous transplantation. The use of GM-CSF as an adjuvant to autologous bone marrow transplantation (ABMT) has significantly reduced the duration of neutropenia after high-dose chemotherapy but failed to accelerate platelet recovery in transplanted patients. The more rapid hematopoietic reconstitution obtained by autologous mobilized peripheral blood progenitor cell transplantation (PBPCT) after high-dose chemotherapy has resulted in its increasing use instead of ABMT. However, PBPCT does not always produce faster platelet engraftment after high-dose chemotherapy, and persistent thrombocytopenia remains a significant clinical problem in PBPC-transplanted patients. The duration of severe thrombocytopenia (requiring frequent platelet transfusions) until platelet recovery varies widely depending on the quality of the autograft and previous radiotherapy or chemotherapy. The median days to reach 20,000/microliters platelets ranged from 10 to 32 days. Pilot clinical studies in which cancer patients were transplanted with enriched CD34+ cell autografts, obtained from G-CSF-mobilized PB, showed a similar platelet recovery after high-dose chemotherapy but also wide variation among the patients. The median days to reach 20,000/microliters platelets ranged from 9 to 38 days. The dose of CFU-GM in the autograft has been identified as the best predictive factor for hematopoietic recovery (p < 0.0001) after high-dose chemotherapy and autologous PBPCT in 118 patients with hematologic malignancies. A similar assessment of the megakaryocyte progenitor cells (BFU-MK and CFU-MK) in the autograft not only could predict time to platelet recovery but also could help to optimize the number and method of mobilization of the PBPC required to shorten the problematic obligatory 2-week duration of thrombocytopenia after high-dose chemotherapy. A routine assessment of the number of BFU-MK and CFU-MK present in each autograft and correlation with platelet recovery after transplantation would enable us to define the clinical threshold cell dose required for rapid platelet recovery. Recently, several non-specific cytokines with thrombopoietic activity have been evaluated in phase I clinical trials, including interleukin-1, interleukin-3 followed by GM-CSF, interleukin-6, and interleukin-11 in cancer patients, showing an encouraging trend toward a decrease in thrombocytopenia after chemotherapy. The recently cloned specific platelet cytokine, thrombopoietin, is currently undergoing phase I clinical studies, and the results are awaited with interest.