High-dose therapy in breast cancer: out of favor but not out of promise

Isolation and transplantation of highly purified autologous peripheral CD34+ progenitor cells: purging efficacy, hematopoietic reconstitution following high dose chemotherapy in patients with breast cancer: results of a feasibility study in Japan

BACKGROUND

High-dose chemotherapy with autologous stem cell support may have some therapeutic impact on certain groups of the patients with advanced breast cancer(BRCA). Since stem cell contamination by tumor cells might contribute to relapse, development of a tumor cell purging technique would improve the clinical outcome. The present study was undertaken to evaluate the purging efficacy of autologous mobilized CD34+peripheral stem cells in patients with breast cancer (BRCA) in an advanced stage or relapse.

METHODS

CD34+cells were selected from autologous peripheral blood stem cells (PBSC) using a clinical scale of magnetic-activated cell sorting system (CliniMACS), followed by high-dose chemotherapy with transplantation of CD34+ selected cells. Amplification of cytokeratin 19 (CK19) and 20 (CK20) gene in leukapheresis products were measured to evaluate the performance of tumor cell elimination.

RESULTS

Seven patients were entered into this study. After leukopheresis, 1 patient was dropped form this study due to poor mobilization. Among 6 patient, a total of 8 CD34+ selection was performed. The median purity and recovery rate of the CD34+ cells post selection was 85.1% (range 62.5-98.1%) and 74.2% (range 50.2-90.2%), respectively. After isolation of CD34+cells, the elimination rate in the logarithmic transformation of CK19 was 2.77 log, and that of CK20 were 2.43 log and 2.53 log. In 4 patients, high-dose chemotherapy was performed, followed by the transplantation of the isolated CD34+cells. Rapid neutrophil recovery, as well as platelet recovery was seen with a median time to reach 0.5 x 109/l neutrophils of 9 days(range 8-9), and 20 x 109/l platelets of 12 days (range 10-13). There was no treatment related death and no serious adverse events directly associated with the selection procedure or infusion of selected cells.

CONCLUSIONS

The present study demonstrated that the CliniMACS system is a highly effective positive selection method and that a high purging efficacy could be obtained without compromising the hematopoietic reconstitution capacity of the graft in BRCA patients undergoing high-dose chemotherapy.

Prognostic significance of the detection of tumour cells in peripheral blood stem cell collections in stage II and III breast cancer patients treated with high-dose therapy

The purpose of this study was to evaluate the incidence and extent of tumour cell contamination in bone marrow specimens and stem cell collections from 34 breast cancer patients undergoing high-dose therapy as adjuvant treatment, and to determine the prognostic significance for the clinical outcome. Tumour cell contamination was evaluated by flow cytometry using a double-colour test and an anti- Pan cytokeratin (CK) antibody. Two out of 34 (6%) baseline bone marrow specimens, none of seven marrow harvests and nine out of 32 aphereses (28%) mobilised from seven out of 27 patients (26%) contained CK+ cells. Tumour contamination was more frequent in patients with 10 or more involved lymph nodes and in those who received a shorter course of adjuvant chemotherapy before mobilisation. At a median follow-up of 43 months, 24 patients are in complete remission, whereas 10 patients experienced recurrence. Out of the 10 patients who relapsed, five (50%) had CK+ peripheral blood stem cell (PBSC) collections, whereas disease recurrence was seen in only two out of 24 (8%) patients who received CK- products (P=0.02). Moreover, CK+ PBSC collections were associated with a significantly shorter event-free survival and overall survival. CK+ collection is an unfavourable prognostic factor for patients treated with high-dose therapy. Whether the negative impact on clinical outcome depends on reinfusion of tumour cells or whether it simply indicates a larger disease extension is still unclear.

Plasma from poorly mobilizing human subjects inhibits cytokine-induced murine blood stem-cell mobilization

BACKGROUND

Cytokine-induced mobilization of hematopoietic stem/progenitor cells to the circulation facilitates efficient harvest of blood stem cells by leukapheresis. Up to 30% of autologous, and 10-20% of allogeneic blood stem-cell donors respond poorly to mobilizing cytokines and preliminary studies implicated a circulating inhibitor of mobilization.

METHODS

In this study, plasma from 11 allogeneic and 23 autologous stem cell donors was assayed for inhibition of mobilization in mice.

RESULTS

There were significant correlations between CD34(+) cells collected/kg human donor weight and spleen weight, CD34(+) CD45(+) cells, GMCFC and HPP-CFC per spleen in murine recipients of these plasma samples. Overall, there was a positive association between transforming growth factor beta (TGF-beta) levels and CD34(+) cells per liter of blood processed (LBP). However, when arbitrarily segregated into good versus poor mobilizers, based on less or greater than 15 million CD34(+) cells collected per LBP, the majority (64%) of normal donors were good mobilizers. The majority of the poor mobilizers (83%) were patients. For a subset of 12 individuals whose plasma strongly inhibited mobilization in the mouse, a significant positive correlation of the extent of inhibition with TGF-beta levels was found. For 11 individuals whose plasma, based on colony assays, enhanced mobilization when injected into mice, no correlation with TGF-beta levels was evident.

DISCUSSION

Elevated plasma TGF-beta levels in some stem-cell donors may be associated with poor stem-cell mobilization. It remains to be determined whether elevation of TGF-beta levels is a cause of, or a compensatory response to, poor mobilization.

An on-site audit of the South African trial of high-dose chemotherapy for metastatic breast cancer and associated publications

PURPOSE

The randomized study reported by Bezwoda et al of high-dose chemotherapy (HDC) for treatment of metastatic breast cancer was audited on site to verify the study results. Additional published studies were reviewed to determine whether they had been subject to the required institutional oversight.

PATIENTS AND METHODS

Ninety patients were reported to have been randomized and treated on this trial. A log of the names, hospital numbers, entry dates, and regimen received had been provided by the principal investigator. A search of more than 15,000 sets of medical records available from two Johannesburg hospitals was performed to locate records for as many of these 90 patients as possible. Standard auditing techniques were used. Additional clinical trials published by Bezwoda were compared against the minutes of the University of the Witwatersrand Committee for Research on Human Subjects to verify review and approval.

RESULTS

Records for only 61 of the 90 patients could be found. Of these 61, only 27 had sufficient records to verify eligibility for the trial by the published criteria. Of these 27, 18 did not meet one or more eligibility criteria. Only 25 patients appeared to have received their assigned therapy temporally associated with their enrollment date, and all but three of these 25 received HDC. The treatment details of individual patients were at great variance from the published data. Nine other trials reported by Bezwoda were not reviewed or approved by the appropriate institutional committee despite statements to the contrary in the publications.

CONCLUSION

The multiple publications of this study do not report verifiable data, and nine other publications coauthored by the principal investigator contain at least one major untrue statement.