Highly purified CD34-positive cells reconstitute hematopoiesis.

Summary:Many poor-risk neuroblastomas and tumours of the Ewing's sarcoma family (ET) recur despite autologous transplants. Recurrence may be due to tumor cells contained in the BM harvests or PBSC harvests. The objectives of this prospective study were to: (1) determine the incidence and degree of tumor cell contamination in paired BM and PBSC harvests; and (2) determine the efficacy of tumor cell purging by immunomagnetic CD34 ؉ cell selection. 198 samples from 11 consecutive patients with neuroblastoma or Ewing's sarcoma were analyzed. We assayed tumor contamination by RT-PCR assay for PGP 9.5, plus immunohistochemistry for neuroblastoma-specific antigens (the latter in neuroblastoma only). None of these patients had tumor cells detected in their BM by clinical histology immediately before BM or PBSC harvests. However, 82% of PBSC and 89% of backup BM harvests were contaminated with tumor by RT-PCR and/or immunocytochemistry assays. Unselected PBSC and BM harvests contained similar quantities of tumor cells (median, ෂ200 000 cells). Cyclophosphamide plus G-CSF mobilization did not affect the incidence or level of contamination in PBSC harvests, as compared to blood obtained before mobilization. Immunomagnetic CD34 ؉ cell selection depleted tumor cells by a median of 3.0 logs for PBSC, and 2.6 logs for BM harvests. Keywords: neuroblastoma; Ewing's sarcoma; autologous transplantation Most childhood solid cancers are sensitive to chemotherapy and radiotherapy, but the prognosis for patients with recurrent, metastatic or refractory pediatric solid tumors remains dismal. 1,2 Recent studies suggest that high-dose myeloablative radio-chemotherapy with autologous bone marrow or peripheral blood stem cell rescue provides the possibility of cure for some patients with advanced neuroblastoma, rhabdomyosarcoma, Wilms' tumor, germ cell tumors, Ewing's sarcoma and peripheral primitive neuroectodermal tumors. [3][4][5][6][7] Nevertheless, only a minority of patients with poor-risk solid cancers treated by high-dose myeloablative radio-chemotherapy are long-term survivors. Relapse posttransplantation can arise from tumor cells in the patient that survive high-dose myeloablative radio-chemotherapy. Gene marking studies have shown that tumor cells which contaminate the hematopoietic graft can also contribute to relapse. 8,9 Previously, we developed a combination highdose myeloablative radio-chemotherapy regimen for a broad range of childhood cancers. 10 We then developed an immunomagnetic CD34 + cell selection technique to 'reverse purge' autologous bone marrow harvests from pediatric patients. 11 With a prototype Isolex device, the estimated median tumor cell depletion was 2.6 logs for bone marrow harvests. However, the tumor cell content was modelled, not actually measured, in this prior study. The efficacy of tumor cell purging by immunomagnetic CD34 + cell selection of mobilized PBSC harvests from pediatric patients has not been reported.PBSC harvests have been reported to contain fewer tumor cells and to be less frequently...

Section: Protocolmentioning

confidence: 99%

Section: Patient Populationmentioning

confidence: 99%

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Frequent detection of tumor cells in hematopoietic grafts in neuroblastoma and Ewing’s sarcoma

Leung¹,

Chen²,

Klann

et al. 1998

“…Selected CD34 + cells are able to reconstitute all lineages after myeloablative chemotherapy in humans. 15,16 The two CD34 + stem cell selection systems adopted in clinical use are based on either biotin-avidin immunoadsorption (Ceprate SC) 17 or indirect immunomagnetic beads (Isolex 300). 18 Most clinical trials of TCD in allo-PBT by means of CD34 + positive selection (allo-PBT/CD34 + ) have been accomplished with the former method, [3][4][5][6][7] and few data about the use of immunomagnetic 520 CML = chronic myeloid leukemia; ALL = acute lymphoblastic leukemia; AML = acute myeloblastic leukemia; CLL = chronic lymphocytic leukemia; NHL = non-Hodgkin lymphoma; MM = multiple myeloma; RAEBt = refractory anemia with excess of blasts in transformation; a = first complete remission or first chronic phase in CML; b = disease chemoresistant or in relapse; Cy = cyclophosphamide (120 mg/kg); TBI = total body irradiation; Bu = busulfan (16 mg/kg); CsA = cyclosporin A; PDN = methylprednisolone; c 3 mg/kg ev from day Ϫ1, maintaining blood levels of 250-400 ng/ml; d 0.5 mg/kg day +7 to +14, 1 mg/kg day +15 to +28, tapering the doses afterwards; e days +1, +3, +6.…”

mentioning

confidence: 99%

Allogeneic transplantation of selected CD34+ cells from peripheral blood: experience of 62 cases using immunoadsorption or immunomagnetic technique

Urbano-Ispizúa¹,

Solano²,

Brunet³

et al. 1998

Summary:The objective of this study was to analyze CD34 + cell recovery and T cell depletion (TCD) achieved in CD34 + cell grafts using either immunoadsorption or immunomagnetic methods applied to leukapheresis products from healthy donors. We also wanted to determine the kinetics of engraftment and incidence and severity of graft-versus-host disease (GVHD) after allogeneic transplantation of selected CD34 + cells. HLA-identical sibling donors received G-CSF. After leukapheresis, peripheral blood progenitor cells were selected using immunoadsorption (Ceprate SC) (n = 38) or immunomagnetic (Isolex 300) (n = 24) methods. Sixty-two patients, with a median age of 42 years (range 17-60) diagnosed with hematological malignancies were conditioned with either cyclophosphamide and total body irradiation (n = 43) or busulphan and cyclophosphamide (n = 19). GVHD prophylaxis consisted of cyclosporin A (CsA) and prednisone (n = 48), CsA alone (n = 11) and CsA and methotrexate (n = 3). The median yield and purity of CD34 + cells after the procedure was 65 and 66% with immunoadsorption, and 48 and 86% with immunomagnetic method, respectively. The median number (range) of CD34 + cells infused into the patients was 3.5 ؋ 10 6 /kg (1-9.6). The median number (range) of CD3 + cells administered was 0.4 ؋ 10 6 /kg (0.01-2) using immunoadsorption and 0.14 ؋ 10 6 /kg (0.03-2.5) using immunomagnetic methods. Neutrophil recovery Ͼ500 and Ͼ1000/ l was achieved at a median (range) of 13 days (8-22) and 14 days (9-31), respectively. Platelets recovered to Ͼ20 000 and Ͼ50 000/ l at a median (range) of 13 days (0-128) and 18 days (0-180), respectively. Two patients developed graft failure. Acute GVHD in patients at risk was clinical grade 0 (n = 43), I (n = 8), II (n = 4) and III (n = 1). No patient developed acute GVHD grade IV. Chronic GVHD was limited in two cases and extensive in four cases. The actuarial probability of acute GVHD II-IV was 10% (95% CI, 1-19%), and of extensive chronic GVHD was 12% (95% CI, 11-13%). The cumulative incidence of transplantrelated mortality was 12.6%, and this figure was 9% at 6 months. In conclusion, with the immunomagnetic procedure, a lower recovery and higher purity of CD34 + cells, and stronger TCD is obtained as compared to immunoadsorption (P = 0.008, P Ͻ 0.0001 and P = 0.0002, respectively). Our results also indicate that allogeneic transplantation of selected CD34 + cells is associated with a very rapid engraftment and with a low incidence of severe GVHD.

“…[1][2][3][4][5] Among the potential benefits of CD34 + cell enrichment for patients with malignant disease is the concomitant depletion of tumor cells in autologous transplant grafts. [5][6][7][8] CD34 antigen has been shown to be present primarily on progenitor and stem cells, and is not found on mature blood cells or non-Hodgkin's lymphoma, myeloma or most solid tumor cells.…”

mentioning

confidence: 99%

Enrichment of peripheral blood CD34+ cells for transplantation using a fully automated immunomagnetic cell selection system and a novel octapeptide releasing agent

Marolleau

Cortivo

Mills

et al. 1999

Summary:Positive selection of CD34 ؉ cells is being increasingly performed to support hematological reconstitution following high-dose and dose-intensive chemotherapy and to reduce the non-target cell content of transplants. The present study was designed to evaluate the performance of an immunomagnetic cell selection system, including comparison of enzyme and peptide releasing agents and of semi-automated and fully automated selection systems. A total of 74 immunomagnetic CD34 ؉ cell selection procedures were performed involving 55 subjects, the majority of whom had hematologic malignancies. Median CD34 ؉ cell purity with a newly developed specific octapeptide releasing agent (98.5%; 81.0-99.0%) was significantly higher (P = 0.002) than that with chymopapain (85.8%; 28.1-99.7%). No significant differences were observed between semi-automated and fully automated systems in CD34 ؉ cell purity or yield or time to WBC or platelet recovery. Immunomagnetic selection was found to provide highly purified populations of CD34 ؉ cells in sufficient numbers for use in transplantation procedures. CD34 ؉ cell transplants supported rapid and reliable hematologic reconstitution. Use of a fully automated system markedly reduced the time and labor required for immunomagnetic selection, potentially affording more standardized and reproducible positive selection of CD34 ؉ cells.