CD34 selections from myeloma peripheral blood cell autografts contain residual tumour cells due to impurity, not to CD34<sup>+</sup> myeloma cells

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: Discussionmentioning

confidence: 99%

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

Leung¹,

Chen²,

Klann

et al. 1998

“…When the total plasma cell population could be detected by patient-specific oligonucleotide PCR. 9 While these PCR methods are extremely sensitive for was studied, definite isotype restriction could be detected in only 16% of harvests. Light chain restriction detecting specific tumour cell populations they have limited ability to quantitate cell numbers and analyse individual was found in 53% of harvests when the mature plasma cells (CD45 12 Five patients failed to provide sufor PERCP) were collected for each sample.…”

Section: /Cd45mentioning

confidence: 99%

Plasma cells in peripheral blood stem cell harvests from patients with multiple myeloma are predominantly polyclonal

Pope

Brown

Gibson

et al. 1997

Summary:Recent studies have reported conflicting levels of tumour cell contamination in PBSC harvests. Radioactive fingerprinting PCR techniques for the immunoglobulin heavy A flow cytometric technique has been developed to detect individual plasma cells in PBSC harvests and to chain genes have found tumour cell contamination in 36% ؊ ) plasma cells and light chain expression in 86% chain restriction can be used as a surrogate marker of clonality. We also wished to correlate light chain restriction and of patients studied. This study has demonstrated that the majority of plasma cells in PBSC harvests from CD19/CD56 expression which has been reported to be a marker of malignant plasma cells. 10,11patients with myeloma are not only immature but are also predominantly polyclonal and that monoclonality is best detected in mature plasma cells.

“…44 Attempts are now being made to positively select hemopoietic from malignant myeloma cell progenitors in stem cell collections but results are still preliminary. [46][47][48] Moreover, the biological and prognostic significance of plasma cells in PBPC collections is still unknown and the most relevant esis is achieved with chemotherapy followed by hemopo- that the use of G-CSF alone is a feasible method for mobil-504-505.…”

mentioning

confidence: 99%

Comparison of peripheral blood progenitor cell mobilization in patients with multiple myeloma: high-dose cyclophosphamide plus GM-CSF vs G-CSF alone

Alegre

Tomás

Martínez‐Chamorro

et al. 1997

133

141

Summary:superior to G-CSF alone based on mean CD34 ؉ cell yield per pheresis, adequate CD34 ؉ cell collections can be achieved with G-CSF alone in most MM patients The best method for peripheral blood progenitor cell (PBPC) mobilization in patients with multiple myeloma with less toxicity and with simplification of the procedure. (MM) remains controversial. We report the results of two different methods of PBPC collection for autologous Keywords: multiple myeloma; PBPC mobilization; GM-CSF; G-CSF transplantation in 40 patients with stage II or III MM. In group I (n = 18), HD-CY, 4 g/m 2 i.v., was administered followed by GM-CSF, 8 g/kg/day s.c., until the end of collection, starting the leukaphereses after hemaPeripheral blood progenitor cells (PBPC) are increasingly tological recovery (Ͼ1 × 10 9 /l WBC). In group II used for hemopoietic autologous rescue afer high-dose ther-(n = 22), G-CSF, 10 g/kg/day s.c., was used alone until apy (HDT) in multiple myeloma (MM). 1-7 The use of perthe last day of collection, starting consecutive aphereses ipheral blood as the source of hematopoietic stem cells has on the 5th day. A minimum of two aphereses were perreplaced the bone marrow due to the rapidity of the formed to collect at least 2 × 10 6 /kg CD34 + cells. Both engraftment and the difficulties in harvesting bone marrow patient groups were comparable for age, sex and clinical cells in most MM patients due to osteoporosis or to preprognostic features as well as previous therapies. In vious irradiation. Another potential advantage for the use group I, the median yields per pheresis were: MNC 1. 47 of PBPC is the lower percentage of tumor cell contami-(1.38-2.32) × 10 8 /kg, CFU-GM 0.82 (0.18-13.2) × 10 4 /kg nation when compared with bone marrow, as recently conand CD34 + cells 1.98 (0.96-6.96) × 10 6 /kg. In group II firmed by molecular methods, 8 although this point is conthese results were: MNC 2.44 (2.06-3.6 × 10 8 /kg) troversial because several recent reports have suggested that (P = 0.03), CFU-GM 0.75 (0.16-7.8) × 10 4 /kg and CD34 + plasma cells may be recruited into the peripheral blood after 1.05 (0.32-3.4) × 10 6 /kg (P = 0.02). The median number mobilizing therapy. 9,10 HDT followed by autologous PBPC of aphereses performed in each group was 5 (4-12) with in MM may induce about 40-60% of complete responses a median of 5.24 ± 2.51 in group I and 3 (2-6) with a in previously untreated patients or in first partial response median of 3.1 (±0.91) in group II (P = NS). Hospitalizafter current induction chemotherapy 1-7,11-13 and some ation for PBPC mobilization was required in all patients investigators have found an advantage regarding response in group I and the treatment-related toxicity was rate, duration of response and progression-free survival greater in this group: 12 patients (66%) developed fever when compared with conventional treatment. 11,12 requiring antibiotics during the neutropenic periodIn spite of the expansion of this strategy, the optimum after HD-CY and six (33%) patients required transsche...