Long-term results of CD34(+) cell transplantation in children with 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.

Autologous hematopoietic stem cell transplantation for pediatric solid tumors

While advances in the treatment of pediatric cancers have increased cure rates, children with metastatic or recurrent solid tumors have a dismal prognosis despite initial transient responses to therapy. Autologous hematopoietic stem cell transplantation takes advantage of the steep dose-response relationship observed with many chemotherapeutic agents. While clearly demonstrated to improve outcomes in patients with metastatic neuroblastoma, autologous hematopoietic stem cell transplantation is also frequently used to treat patients with other high-risk diseases such as Ewing sarcoma, osteosarcoma, rhabdomyosarcoma, Wilms' tumor, retinoblastoma, germ cell tumors, lymphomas and brain tumors. Most published experience consists of retrospective, single-arm studies; randomized clinical trials are lacking, due in part to the rarity of pediatric cancers treatable by autologous hematopoietic stem cell transplantation. These published literature demonstrate that autologous hematopoietic stem cell transplantation results in most cases in equivalent or superior outcomes when compared with conventional therapies. However, patient heterogeneity, patient selection, graft characteristics and processing and the varied conditioning regimens are additional factors to consider. Since the inception of autologous hematopoietic stem cell transplantation, regimen-related toxicity has markedly decreased and the vast majority of treatment failures are now due to disease recurrence. Prospective clinical trials are needed to identify specific high-risk patient populations, with randomization (when possible) to compare outcomes of patients undergoing autologous hematopoietic stem cell transplantation with those receiving standard therapy. In addition, investigators need to better define the role of autologous hematopoietic stem cell transplantation in these solid tumors, particularly in combination with other therapeutic modalities such as immunotherapy and novel cell processing methodologies.

Peripheral blood stem cell collection in low-weight children: retrospective comparison of two apheresis devices

BACKGROUND

Apheresis is a major challenge in peripheral stem cell collection from low-weight children with cancer. Comparisons between the new apheresis device Optia (TerumoBCT) and the earlier COBE Spectra (CaridianBCT) have been performed in adults but not in low-weight children. The objective was to compare the performance of these two devices in small children.

STUDY DESIGN AND METHODS

In this retrospective study, all patients were reviewed weighing less than 15 kg undergoing stem cell collection using the Optia device between April 2011 and April 2012. They were paired on weight in a 3:1 ratio with patients whose cells had been collected with the COBE Spectra since 2006.

RESULTS

Six patients were treated with the Optia and were matched with 18 patients treated with the Spectra. No side effects occurred. Collection efficiency (CE) was similar between the two groups (50% vs. 47%), but CD34 cell blood clearance was lower with the Optia (0.4 mL/min/kg vs. 0.6 mL/min/kg, p < 0.01). Platelet (PLT) loss and hemoglobin (Hb) loss were significantly reduced with the Optia (respectively, 32% vs. 54%, p < 0.01; and 1.4 g/dL vs. 2.9 g/dL, p < 0.01). Apheresis duration was increased with the Optia (159 min vs. 134 min, p < 0.05). The cell product harvested with the Optia had a lower volume and lower hematocrit, but similar white blood cell and PLT content.

CONCLUSION

Compared with the Spectra, the Optia allows similar CE with a reduced PLT and Hb loss but with a longer duration.

A pilot study of tandem high-dose chemotherapy with stem cell rescue as consolidation for high-risk neuroblastoma: Children's Oncology Group study ANBL00P1

Increasing treatment intensity has improved outcomes for children with neuroblastoma. We performed a pilot study in the Children’s Oncology Group (COG) to assess feasibility and toxicity of a tandem myeloablative regimen without total body irradiation (TBI) supported by autologous CD34 selected peripheral blood stem cells. Forty-one patients with high-risk neuroblastoma were enrolled; eight patients did not receive any myeloablative consolidation procedure, and seven received only one. Two patients out of 41 (4.9%) experienced transplant-related mortality. CD34 selection was discontinued after subjects were enrolled due to serious viral illness. From the time of study enrollment, the overall 3-year event-free survival (EFS) and overall survival (OS) were 44.8±9.6% and 59.2±9.2% (N=41). These results demonstrate that tandem transplantation in the cooperative group setting is feasible and support a randomized comparison of single versus tandem myeloablative consolidation with PBSC support for high-risk neuroblastoma.

Immunomodulation with dendritic cells and donor lymphocyte infusion converge to induce graft vs neuroblastoma reactions without GVHD after allogeneic bone marrow transplantation

BACKGROUND

Mounting evidence points to the efficacy of donor lymphocyte infusion (DLI) and immunisation with tumour-pulsed dendritic cells (DC) in generating graft vs leukaemia reactions after allogeneic bone marrow transplantation (BMT). We assessed the efficacy of DLI and DC in generating potent graft vs neuroblastoma tumour (GVT) reactions following allogeneic BMT.

METHODS

Mice bearing congenic (H2K(a)) Neuro-2a tumours were grafted with allogeneic (H2K(b)) T-cell-depleted bone marrow cells. Tumour-pulsed donor DC (DC(Neuro2a)) were inoculated (on day +7) in conjunction with donor (H2K(b)) and haploidentical (H2K(a/b)) lymphocytes.

RESULTS

Murine Neuro-2a cells elicit immune reactions as efficient as B lymphoma in major histocompatibility complex antigen-disparate mice. Lymphopenia induced by conditioning facilitates GVT, and transition to adaptive immunity is enhanced by simultaneous infusion of and DC(Neuro2a) and lymphocytes devoid of graft vs host (GVH) activity (H2K(a/b)). In variance, the efficacy of DC-mediated immunomodulation was diminished by severe graft vs host disease (GVHD), showing mechanistic dissociation and antagonising potential to GVT.

CONCLUSIONS

The GVHD is not a prerequisite to induce GVT reactivity after allogeneic BMT, but is rather detrimental to induction of anti-tumour immunity by DC-mediated immunomodulation. Simultaneous inoculation of tumour-pulsed donor DC and DLI synergise in stimulation of potent GVT reactions to the extent of eradication of established NB tumours.

Autologous and allogeneic cellular therapies for high-risk pediatric solid tumors

Since the 1950s, the overall survival of children with cancer has gone from almost zero to approaching 80%. Although there have been notable successes in treating solid tumors such as Wilms tumor, some childhood solid tumors have continued to elude effective therapy. With the use of megatherapy techniques such as tandem transplantation, dose escalation has been pushed to the edge of dose-limiting toxicities, and any further improvements in event-free survival will have to be achieved through novel therapeutic approaches. This article reviews the status of autologous and allogeneic hematopoietic stem cell transplantation (HSCT) for many pediatric solid tumor types. Most of the clinical experience in transplant for pediatric solid tumors is in the autologous setting, so some general principles of autologous HSCT are reviewed. The article then examines HSCT for diseases such as Hodgkin disease, Ewing sarcoma, and neuroblastoma, and the future of cell-based therapies by considering some experimental approaches to cell therapies.

Graft versus neuroblastoma reaction is efficiently elicited by allogeneic bone marrow transplantation through cytolytic activity in the absence of GVHD

Continuous efforts are dedicated to develop immunotherapeutic approaches to neuroblastoma (NB), a tumor that relapses at high rates following high-dose conventional cytotoxic therapy and autologous bone marrow cell (BMC) reconstitution. This study presents a series of transplant experiments aiming to evaluate the efficacy of allogeneic BMC transplantation. Neuro-2a cells were found to express low levels of class I major histocompatibility complex (MHC) antigens. While radiation and syngeneic bone marrow transplantation (BMT) reduced tumor growth (P < 0.001), allogeneic BMT further impaired subcutaneous development of Neuro-2a cells (P < 0.001). Allogeneic donor-derived T cells displayed direct cytotoxic activity against Neuro-2a in vitro, a mechanism of immune-mediated suppression of tumor growth. The proliferation of lymphocytes from congenic mice bearing subcutaneous tumors was inhibited by tumor lysate, suggesting that a soluble factor suppresses cytotoxic activity of syngeneic lymphocytes. However, the growth of Neuro-2a cells was impaired when implanted into chimeric mice at various times after syngeneic and allogeneic BMT. F1 (donor-host) splenocytes were infused attempting to foster immune reconstitution, however they engrafted transiently and had no effect on tumor growth. Taken together, these data indicate: (1) Neuro-2a cells express MHC antigens and immunogenic tumor associated antigens. (2) Allogeneic BMT is a significantly better platform to develop graft versus tumor (GVT) immunotherapy to NB as compared to syngeneic (autologous) immuno-hematopoietic reconstitution. (3) An effective GVT reaction in tumor bearing mice is primed by MHC disparity and targets tumor associated antigens.

Immunotherapy for pediatric cancer

Improvements in adult cancer survivorship can be achieved from behavioral changes and adopting screening programs. Yet, these approaches cannot be readily applied to lower the morbidity and mortality from childhood cancers. Rather, pediatric oncologists must rely on procedures and therapies to treat, rather than prevent malignancies. The systematic application of chemotherapy, radiation therapy, and surgery has led to remarkable advances in survival but these improvements have come at a cost. Children routinely receive chemotherapy agents that were designed decades ago, and these drugs have predictable side effects that result in the loss of potential for long-term survivors. The advent of targeted applications of immune-based therapies offers children with cancer a new class of oncolytic therapies that may be used to treat disease refractory to conventional approaches and lessen the toxicity of current treatment regimens without compromising remission. This review explores how 3 components of the immune system--T cells, natural killer (NK) cells, and antibodies--can be used for therapy of pediatric malignancies.

Stem cell transplantation for neuroblastoma

High-risk neuroblastoma is a childhood malignancy with a poor prognosis. Gradual improvements in survival have correlated with therapeutic intensity, and the ability to harvest, process and store autologous hematopoietic stem cells has allowed for dose intensification beyond marrow tolerance. The use of high-dose chemotherapy with autologous hematopoietic stem cell rescue in consolidation has resulted in improvements in survival, although further advances are still needed. Newer approaches to SCT and supportive care, most notably the transition to PBSC, have resulted in further improvement in survival and decreases in treatment-related mortality. Research into experimental approaches to hematopoietic SCT is ongoing.

A Novel HSV-1 Virus, JS1/34.5−/47−, Purges Contaminating Breast Cancer Cells From Bone Marrow

PURPOSE

Oncolytic herpes simplex virus type 1 (HSV-1) vectors show considerable promise as agents for cancer therapy. We have developed a novel recombinant HSV-1 virus (JS1/34.5-/47-) for purging of occult breast cancer cells from bone marrow of patients. Here, we evaluate the therapeutic efficacy of this oncolytic virus.

EXPERIMENTAL DESIGN

Electron microscopy was used to determine whether human breast cancer and bone marrow cells are permissive for JS1/34.5-/47- infection. Subsequently, the biological effects of JS1/34.5-/47- infection on human breast cancer cells and bone marrow were established using cell proliferation and colony formation assays, and the efficiency of cell kill was evaluated. Finally, the efficiency of JS1/34.5-/47- purging of breast cancer cells was examined in cocultures of breast cancer cells with bone marrow as well as bone marrow samples from high-risk breast cancer patients.

RESULTS

We show effective killing of human breast cancer cell lines with the JS1/34.5-/47- virus. Furthermore, we show that treatment with JS1/34.5-/47- can significantly inhibit the growth of breast cancer cell lines without affecting cocultured mononuclear hematopoietic cells. Finally, we have found that the virus is effective in destroying disseminated tumors cells in bone marrow taken from breast cancer patients, without affecting the hematopoietic contents in these samples.

CONCLUSION

Collectively, our data show that the JS1/34.5-/47- virus can selectively target breast cancer cells while sparing hematopoietic cells, suggesting that JS1/34.5-/47- can be used to purge contaminating breast cancer cells from human bone marrow in the setting of autologous hematopoietic cell transplantation.

Peripheral blood stem cell tumor cell contamination and survival of neuroblastoma patients

PURPOSE

Contribution of peripheral blood stem cell (PBSC) contaminating tumor cells to subsequent relapse and overall survival of neuroblastoma patients remains controversial.

EXPERIMENTAL DESIGN

Neuroblastoma cell contamination of 27 PBSC harvests from stage IV neuroblastoma patients was assessed by quantitative RT-PCR for both tyrosine hydroxylase (TH) and GD2 synthase (GD2-s). The effect of PBSC contamination on survival was then analyzed.

RESULTS

Seven PBSC tested negative for both markers; 19 were positive for GD2-s, 6 for TH, with 5 positive for both. Survival of the 20 patients with positive PBSC did not differ from that of the patients with negative PBSC (log-rank test, P = 0.134 and 0.218 for event-free survival and overall survival, respectively). By considering the TH and GD2-s results independently, a borderline (P = 0.053) negative effect on event-free survival was observed in patients reinfused with GD2-s-positive PBSC. When the status at transplant was taken into account, only the event-free survival of the patients rescued when in complete remission with GD2-s-negative PBSC was better, although not significantly, than that of patients infused with GD2-s-positive PBSC.

CONCLUSIONS

Our results obtained in a small cohort of homogeneously treated stage IV patients suggest that patient survival is not affected by PBSC contamination with the exception of a borderline negative effect on event-free survival in patients rescued when in complete remission.

Long-term results of high-dose chemotherapy and autologous stem cell rescue for high-risk neuroblastoma patients: a report of the Spanish working party for BMT in children (Getmon)

The authors retrospectively analyzed the long-term outcome of 67 patients over 1 year of age at diagnosis with high-risk neuroblastoma (stage 4 or stage 3 with N-myc amplification) who were treated with megatherapy and stem cell rescue from 1984 to 1998. Median age at transplant was 4 years (range 1.6-15 years). The source of cells was peripheral stem cells in 29 and bone marrow in 38 patients. In 12 patients, an in vitro purging of bone marrow harvest was performed. Most patients were conditioned with melphalan, BCNU, and VM-26. After transplant 19 patients received complementary treatment with IL-2 (16) or 13-cis-retinoic acid (3). Six patients (8%) died from transplant-related toxicity and 39 from disease progression. Three patients were alive with active disease at the time of analysis. Nineteen patients are alive and disease-free at a median follow-up of 104 months. Five-year event-free survival is 0.30. Survival of patients who received a purged graft was not significantly better than the rest. Post-transplant complementary treatment significantly improved overall and event-free survival (p = .01 and p = .04, respectively).

[Cell therapy for cancer treatment in children]

The cure rate for cancer in children is currently almost 75%. This rate has remained fairly constant over the past few years, which suggests that the limits of today's curative treatment potential have been reached. The development of cell therapy techniques opens up new therapeutic possibilities in paediatric oncology. Here, we deal both with a number of cell therapy techniques, which have already proved their efficacy in children, and other more innovative approaches, which require validation. Examples of the use of autologous and allogeneic cells are described. Clinical studies and their results, while often preliminary, are reported. The importance of well run clinical research, a clear and progressive legal framework and the necessary substantial economic support for the development of cell therapy are underlined.

Ex vivo expansion of autologous PB CD34+ cells provides a purging effect in children with neuroblastoma

Peripheral blood CD34+ cell samples from eight children with advanced neuroblastoma and from 10 healthy adult donors were seeded at 5 x 10(4) cells/ml in stroma-free, serum-free medium with FL, SCF, MGDF (100 ng/ml each), G-CSF, IL6 (10 ng/ml each) and IL3 (5 ng/ml), and incubated for 10 days. The levels of expansion of PBCD34+ cells observed in neuroblastoma patients, with up to 214-fold expansion for total nucleated cells, 39-fold for CD34+ cells, 79-fold for CFU-GM and nine-fold for LTC-IC were identical to those obtained with PBCD34+ cells of healthy donors (P>/=0.5). All samples from patients with neuroblastoma and five donor's PBCD34+ cell samples contaminated with IMR-32 neuroblasts, were screened for the number of tyrosine hydroxylase (TH) mRNA transcript using LightCycler software. In all samples, progressive 1.9-4.4 log decreases in the number of TH transcripts were observed between days 0 and 10 of expansion. Our results show that in extensively pretreated children with neuroblastoma, the culture conditions that were effective for BM and CB cell expansion can generate an expansion of PBCD34+ cells and provide a purge of tumour cells.

Significance of molecular quantification of minimal residual disease in metastatic neuroblastoma

Molecular detection of tumor cells is the most sensitive approach to study residual disease in bone marrow (BM), peripheral blood (PB), and peripheral blood stem cell (PBSC) autografts from children with metastatic neuroblastoma (NB). We have developed a real-time PCR assay that allows the quantification of tyrosine hydroxylase (TH) mRNA, a tissue-specific marker of neuroblasts. We investigated a total of 165 BM, PB, and PBSC samples from 30 children over 1 year of age with stage IV NB and correlated the findings with disease status and patient survival. The levels of TH mRNA agreed well with clinical status and were significantly different across the groups that included samples obtained from patients at diagnosis, after three cycles of chemotherapy, in complete or very good partial remission and at relapse. We found that overall survival was significantly worse for patients with >1000 TH copies in BM after initial chemotherapy (p=0.0075). In 57% of cases, autologous PBSC harvests were found to be contaminated by neuroblasts, the level of TH >500 copies being associated with a decreased survival (p=0.003). In addition, molecular quantification enabled an estimation of tumor depletion in contaminated autografts using CD34 selection (median, 3 logs). In conclusion, quantification of minimal residual disease in metastatic NB using real-time RT-PCR for TH mRNA appears to be of potential clinical value. Further studies are needed to ascertain prognostic implications of molecular analysis of residual disease.

High-risk neuroblastoma in Ontario: a report of experience from 1989 to 1995

PURPOSE

We did a population-based study of children with high-risk neuroblastoma to determine their survival and look for factors that had an impact on survival.

METHODS

We carried out a retrospective cohort study of patients diagnosed in Ontario from 1989 to 1995. 162 cases of neuroblastoma were diagnosed in the province with 70 (43%) considered high-risk: all were older than one year of age, with 15 patients classified as International Neuroblastoma Staging System (INSS) stage 3, and 55 INSS stage 4.

RESULTS

Stage 3 patients did significantly better than Stage 4 patients with a 5-year overall survival of 67.7% and 22.7% respectively (P = 0.015). In stage 4 patients achieving at least a partial response to up-front therapy and surviving for at least 9.5 months after diagnosis (the median time to transplant), there was no difference in survival between the 19 transplant patients and the 17 treated with chemotherapy alone (P = 0.75). However, patients transplanted by peripheral stem cell (PSC) collection did significantly better than both the bone marrow transplantation (P = 0.002) and chemotherapy-alone group (P = 0.047). There was a significant difference in up-front chemotherapy and use of radiation in the three groups (P < 0.001 and P = 0.01 respectively), but no difference in the incidence of bone and bone marrow metastases, MYCN amplification or unfavorable histology.

CONCLUSIONS

In this nonrandomized study, we found that stage 4 neuroblastoma patients alive more than 9.5 months after diagnosis, with at least a partial response to initial therapy, did significantly better with PSC transplant compared with bone marrow transplantation or chemotherapy alone.

CD34 selection as a stem cell purging strategy for neuroblastoma: preclinical and clinical studies

BACKGROUND

The suitability of CD34 selection for purging peripheral blood progenitor cells (PBPC) collected from patients with neuroblastoma (NB) has been called into question, largely because of reports of detection of low levels of CD34 on the surface of some NB cell lines and tumors.

PROCEDURE

We used three approaches to address the issue of purging of NB from stem cell specimens and possible labeling of NB: 1) Flow cytometric detection of CD34 on NB cell lines. We assessed CD34 expression using a panel of anti-CD34 monoclonal antibodies (MoAbs) including 9C5, 12.8, and QBend10 and showed no increase in labeling over secondary-only control. 2) Spiking experiments with the Isolex 50 system. NB cell lines were used to contaminate aliquots of PBPC collections, after which the products were purified using the Isolex 50. Purging of NB was assessed by quantitative multiplex RT-PCR (TaqMan system) using a tumor-specific transcript, GAGE. We demonstrated >2 logs of tumor cell depletion from these specimens. 3) Analysis of clinical specimens. PBPC pre- and post-CD34 selection were analyzed from patients treated on the CHP-594 transplant trial.

RESULTS

In nine specimens selected using the Ceprate LC CD34 selection system where tumor was detectable by immunocytochemistry preselection, we observed >2.4 to >4.6 logs of NB purging after selection. We then analyzed 23 aliquots of PBPC infused into patients post-CD34 selection and compared them to the product preselection; 20/23 specimens showed depletion of NB, although some level of GAGE message was observed in most post-CD34 selection specimens.

CONCLUSION

These data show that purging of NB from PBPC specimens using CD34 selection is feasible, yielding infused products that are negative at the level of ICC but often positive at the level of RT-PCR.

Rapid-sequence tandem transplant for children with high-risk neuroblastoma

BACKGROUND

The majority of patients with high risk neuroblastoma (NB) still relapse.

PROCEDURE

We designed a Phase II trial for children with advanced NB utilizing a program of induction chemotherapy followed by tandem high-dose chemoradiotherapy with stem cell rescue (HDC/SCR) in rapid sequence. Fifty-five patients were evaluable, ages 1-14 years, and 97 cycles of HDC/SCR have been completed to date. Pheresis was possible for every patient, despite their young age, with an average of 7.2 x 10(6) CD34+ cells/kg available to support each HDC/SCR cycle.

RESULTS

Engraftment was rapid, with median time to neutrophil engraftment of 11 days. Five patients who completed the first HDC course did not complete the second and there were four toxic deaths. With a median follow-up of 24 months from diagnosis, 38 of 55 patients (3-year EFS 59%) remain event-free. A subset of the patients received stem cells purged by CD34 selection. The engraftment and EFS of these patients are similar to the overall group.

CONCLUSION

This work demonstrates that a tandem transplant regimen for high-risk NB is a feasible treatment strategy in children and may improve disease-free survival.

Using peripheral blood progenitor cells (PBPC) for transplantation in pediatric patients: a state-of-the-art review

This paper presents a state-of-the-art review of using mobilized-peripheral blood progenitor cells (PBPC) for transplantation in children. Our own data and those from Medline searches and meeting reports, are analyzed and presented for the different sections that involve transplantation. Recommendations concerning the choice of mobilization regimens, venous access, priming of separator extracorporeal line, anticoagulation, and number of CD34+ cells to infuse for rapid engraftment are proposed. In the allogeneic setting, we analyze ethical and safety aspects of pediatric donor mobilization and collection. Data from the literature suggest that the use of cytokine-mobilized PBPC for allogeneic transplantation appears to be safe both for pediatric donors and patients leading a rapid hematopoietic engraftment with a similar incidence of acute graft-versus-host disease (GVHD). The high incidence of chronic GVHD and its management emerge as the most concerning aspect in allogeneic PBPC transplantation.