Haploidentical Stem Cell Transplantation for Refractory/Relapsed Neuroblastoma.

Pediatric patients with refractory or relapsed metastatic neuroblastoma (NBL) have a poor prognosis despite autologous stem cell transplantation (SCT). Allogeneic SCT from a haploidentical donor has a remarkable alloreactive effect in patients with leukemia; thus, we evaluated this approach in children with very high-risk NBL. We analyzed data from 2 prospective phase I/II trials. A total of 26 patients with refractory (n = 5), metastatic relapsed (n = 20), or locally relapsed MYCN-positive (n = 1) NBL received a median of 17 × 106/kg T/B cell-depleted CD34+ stem cells with 68 × 103/kg residual T cells and 107 × 106/kg natural killer cells. The conditioning regimen comprised melphalan, fludarabine, thiotepa, OKT3, and a short course of mycophenolate mofetil post-transplantation. Engraftment occurred in 96% of the patients. Event-free survival and overall survival at 5 years were 19% and 23%, respectively. No transplantation-related mortality was observed, and the single death was due to progression/subsequent relapse. The median duration of follow-up was 8.1 years. Patients in complete remission before SCT had a significantly better prognosis than those with residual tumor load (P < .01). All patients with progressive disease before SCT relapsed within 1 year. Grade II and grade III acute graft-versus-host disease (GVHD) occurred in 31% and 12% of the patients, respectively. Chronic limited and extensive GVHD occurred in 28% and 10%, respectively. Our data indicate that haploidentical SCT is a feasible treatment option that can induce long-term remission in some patients with NBL with tolerable side effects, and may enable the development of further post-transplantation therapeutic strategies based on the donor-derived immune system.

Label-free separation of neuroblastoma patient-derived xenograft (PDX) cells from hematopoietic progenitor cell products by acoustophoresis.

BACKGROUND: Graft-contaminating tumor cells correlate with inferior outcome in high-risk neuroblastoma patients undergoing hematopoietic stem cell transplantation and can contribute to relapse. Motivated by the potential therapeutic benefit of tumor cell removal as well as the high prognostic and diagnostic value of isolated circulating tumor cells from stem cell grafts, we established a label-free acoustophoresis-based microfluidic technology for neuroblastoma enrichment and removal from peripheral blood progenitor cell (PBPC) products. METHODS: Neuroblastoma patient-derived xenograft (PDX) cells were spiked into PBPC apheresis samples as a clinically relevant model system. Cells were separated by ultrasound in an acoustophoresis microchip and analyzed for recovery, purity and function using flow cytometry, quantitative real-time PCR and cell culture. RESULTS: PDX cells and PBPCs showed distinct size distributions, which is an important parameter for efficient acoustic separation. Acoustic cell separation did not affect neuroblastoma cell growth. Acoustophoresis allowed to effectively separate PDX cells from spiked PBPC products. When PBPCs were spiked with 10% neuroblastoma cells, recoveries of up to 98% were achieved for PDX cells while more than 90% of CD34+ stem and progenitor cells were retained in the graft. At clinically relevant tumor cell contamination rates (0.1 and 0.01% PDX cells in PBPCs), neuroblastoma cells were depleted by more than 2-log as indicated by RT-PCR analysis of PHOX2B, TH and DDC genes, while > 85% of CD34+ cells could be retained in the graft. CONCLUSION: These results demonstrate the potential use of label-free acoustophoresis for PBPC processing and its potential to develop label-free, non-contact tumor cell enrichment and purging procedures for future clinical use.

High-dose iodine-131-metaiodobenzylguanidine with haploidentical stem cell transplantation and posttransplant immunotherapy in children with relapsed/refractory neuroblastoma.

We evaluated the feasibility and efficacy of using high-dose iodine-131-metaiodobenzylguanidine ((131)I-MIBG) followed by reduced-intensity conditioning (RIC) and transplantation of T cell-depleted haploidentical peripheral blood stem cells (designated haplo-SCT) to treat relapsing/refractory neuroblastoma (RRNB). Five RRNB patients were enrolled: 4 with relapse (3 after autologous SCT) and 1 with induction therapy failure. The preparative regimen included high-dose (131)I-MIBG on day -20, followed by fludarabine (Flu), thiotepa, and melphalan (Mel) from day -8 to -1. Granulocyte-colony stimulating factor (G-CSF)-mobilized, T cell-depleted haploidentical paternal stem cells were infused on day 0 together with cultured donor mesenchymal stem cells. A single dose of rituximab was given on day +1. After cessation of short immunosuppression (mycophenolate, OKT3), 4 children received donor lymphocyte infusion (DLI). (131)I-MIBG infusion and RIC were well tolerated. All patients engrafted. No primary acute graft-versus-host disease (aGVHD) was observed. Four children developed aGVHD after DLI and were successfully treated. Analysis of immunologic recovery showed fast reappearance of potentially immunocompetent natural killer (NK) and T cells, which might have acted as effector cells responsible for the graft-versus-tumor (GVT) effect. Two children are alive and well, with no evidence of disease 40 and 42 months after transplantation. One patient experienced late progression with new bone lesions (sternum) 38 months after haplo-SCT, and is being treated with local irradiation and reinstituted DLI. One patient rejected the graft, was rescued with autologous backup, and died of progressive disease 5 months after transplantation. Another child relapsed 7 months after transplantation and died 5 months later. High-dose (131)I-MIBG followed by RIC and haplo-SCT for RRNB is feasible and promising, because 2 of 5 children on that regimen achieved long-lasting remission. Further studies are needed to evaluate targeted therapy and immune-mediated tumor control in high-risk neuroblastoma.

Label-free neuroblastoma cell separation from hematopoietic progenitor cell products using acoustophoresis - towards cell processing of complex biological samples.

Processing of complex cell preparations such as blood and peripheral blood progenitor cell (PBPC) transplants using label-free technologies is challenging. Transplant-contaminating neuroblastoma cells (NBCs) can contribute to relapse, and we therefore aimed to provide proof-of-principle evidence that label-free acoustophoretic separation can be applied for diagnostic NBC enrichment and removal ("purging") from human blood and PBPC products. Neuroblastoma cells spiked into blood and PBPC preparations served as model systems. Acoustophoresis enabled to enrich NBCs from mononuclear peripheral blood cells and PBPC samples with recovery rates of up to 60-97%. When aiming at high purity, NBC purities of up to 90% were realized, however, compromising recovery. Acoustophoretic purging of PBPC products allowed substantial tumour cell depletion of 1.5-2.3 log. PBPC loss under these conditions was considerable (>43%) but could be decreased to less than 10% while still achieving NBC depletion rates of 60-80%. Proliferation of cells was not affected by acoustic separation. These results provide first evidence that NBCs can be acoustically separated from blood and stem cell preparations with high recovery and purity, thus indicating that acoustophoresis is a promising technology for the development of future label-free, non-contact cell processing of complex cell products.

Rapid and effective CD3 T-cell depletion with a magnetic cell sorting program to produce peripheral blood progenitor cell products for haploidentical transplantation in children and adults.

BACKGROUND: Effective T-cell depletion is a prerequisite for haploidentical peripheral blood progenitor cell (PBPC) transplantation. This study was performed to investigate the performance of magnetic cell sorting-based direct large-scale T-cell depletion, which is an attractive alternative to standard PBPC enrichment procedures. STUDY DESIGN AND METHODS: PBPCs were harvested from 11 human leukocyte antigen (HLA)-haploidentical donors. T cells labeled with anti-CD3-coated beads were depleted with a commercially available magnetic separation unit (CliniMACS, Miltenyi Biotec) with either the Depletion 2.1 (D2.1, n=11) or the novel Depletion 3.1 (D3.1, n=12) program. If indicated, additional CD34+ selections were performed (n=6). Eleven patients received T-cell-depleted grafts after reduced-intensity conditioning. RESULTS: The median log T-cell depletion was better with the D2.1 compared to the D3.1 (log 3.6 vs. log 2.3, p<0.05) and was further improved by introducing an immunoglobulin G (IgG)-blocking step (log 4.5 and log 3.4, respectively). The D3.1 was superior to the D2.1 (p<0.05) in median recovery of CD34+ cells (90% vs. 78%) and in median recovery of CD3- cells (87% vs. 76%). The median processing times per 10(10) total cells were 0.90 hours (D2.1) and 0.35 hours (D3.1). The transplanted grafts (directly T-cell-depleted products with or without positively selected CD34+ cells) contained a median of 10.5 x 10(6) per kg CD34+, 0.93x10(5) per kg CD3+, and 11.6x10(6) per kg CD56+. Rapid engraftment was achieved in 10 patients. The incidences of acute graft-versus-host disease were less than 10 percent (Grade I/II) and 0 percent (Grade III/IV). CONCLUSION: The novel D3.1 program with IgG blocking enables highly effective, time-saving large-scale T-cell depletion. Combining direct depletion techniques with standard CD34+ selection enables the composition of grafts optimized to the specific requirements of the patients.