Immune recovery in breast cancer patients after tandem high-dose chemotherapy rescued by selected CD34+ cells.

TANDEM (TWO CONSECUTIVE CYCLES) high-dose chemotherapy with autologous hematopoietic stem cell support is a feasible treatment adopted as consolidation treatment for multiple myeloma, ovarian cancer, germ cell tumors, and also for high-risk and metastatic breast cancer. Since gene-marking studies of patients with hematological malignancy or neuroblastoma have showed that some relapses contain the markers of the reinfused cells (1,2), autologous CD341 cell-positive selection is performed with the intent to avoid tumor cell contamination of the grafts. Both dose-intensive chemotherapy with hematopoietic growth-factor support (3,4) and high-dose chemotherapy rescued by autologous bone marrow (BM) or peripheral blood progenitor cell (PBPC) transplant (5) can lead to immune damage, and immune reconstitution in adults showed a prolonged inversion of CD4/CD8 ratio, because of a long-lasting diminished number of CD41 cells. Positive selection of CD341 cells causes a further T cell depletion of the graft (by reducing residual mature T cells at negligible numbers) and can contribute to the post transplant lymphocyte regeneration delay (6). Decreased counts of CD41 lymphocytes in patients with hematological malignancies receiving high-dose chemotherapy rescued with selected CD341 cells are reported to increase the risk of opportunistic infectious diseases such as viral, fungal, or parasitic infections (7–9). We report our experience on the effects of a tandem course of high-dose chemotherapy as consolidation treatment rescued with CD341-selected cell transplants on immune reconstitution in breast cancer patients and evaluate the risk of opportunistic infectious complications in the early post-transplant. From November, 1997, to November, 1999, 12 patients (median age 40 years, range 31–57) with breast cancer not previously treated (7 high risk and 5 metastatic) received tandem high-dose chemotherapy as consolidation treatment after four cycles of FEC (5-Fluorouracil 600 mg/m2 i.v. on day 1; Epirubicin 90 mg/m2 i.v. on day 1; Cyclophosphamide 600 mg/m2 i.v. on day 1; every three weeks) regimen. Mobilizing treatment consisted of the same regimen supported by granulocyte-colony stimulating factor (G-CSF) 5 mc/kg per day s.c. from day 1 2 until end of aphereses. The threshold of 2 3 106/kg of CD341 cells to support each course of high-dose chemotherapy was requested. After collection, peripheral blood mononuclear cells were separated using a IBM 2991 cell separator and then underwent CD341 positive selection. In 6 patients, the capture method for CD341 cells was based on avidin-biotin immunoadsorption column Ceprate SC Stem Cell Concentration System, Cell Pro®; in the other 6 patients, the positive selection was based on immunomagnetic beads (Isolex 300i Magnetic Cell Separation System, Nexell®). Both systems were used according to the manufacturer’s specifications. After enrichment was completed, a median of CD341selected cells of 3.73 106/kg (range 2.1–8.8) for the first transplant and 4.73 106/kg (range 3.0–8.7) for the second transplant was obtained. Median purity of the final product was 92.3% and did not differ significantly between avidin-biotin immunoadsorption columns and immunomagnetic beads: 88.5% and 92.9% (p . 0.06), respectively. The CD341-selected cell-supported inten-