Monoclonal antibody-based therapy for neuroblastoma

High-Risk Neuroblastoma Challenges and Opportunities for Antibody-Based Cellular Immunotherapy

Immunotherapy has emerged as an attractive option for patients with relapsed or refractory high-risk neuroblastoma (HRNB). Neuroblastoma (NB), a sympathetic nervous system cancer arising from an embryonic neural crest cell, is heterogeneous clinically, with outcomes ranging from an isolated abdominal mass that spontaneously regresses to a widely metastatic disease with cure rates of about 50% despite intensive multimodal treatment. Risk group stratification and stage-adapted therapy to achieve cure with minimal toxicities have accomplished major milestones. Targeted immunotherapeutic approaches including monoclonal antibodies, vaccines, adoptive cellular therapies, their combinations, and their integration into standard of care are attractive therapeutic options, although curative challenges and toxicity concerns remain. In this review, we provide an overview of immune approaches to NB and the tumor microenvironment (TME) within the clinical translational framework. We propose a novel T cell-based therapeutic approach that leverages the unique properties of tumor surface antigens such as ganglioside GD2, incorporating specific monoclonal antibodies and recent advancements in adoptive cell therapy.

Treatment and outcomes of high-risk neuroblastoma in Southeast Asia: a single-institution experience and review of the literature

INTRODUCTION

In Europe and North America, the majority of children with high-risk neuroblastoma survive the disease. Elsewhere, the treatment outcomes are poor.

METHODS

A retrospective review of children treated for high-risk neuroblastoma in a single institution in Singapore from 2007 to 2019 was carried out. Treatment consisted of intensive chemotherapy, surgery aimed at gross total resection of residual disease after chemotherapy, consolidation with high-dose therapy followed by autologous stem cell rescue, and radiotherapy to the primary and metastatic sites followed by maintenance treatment with either cis-retinoic acid or anti-disialoganglioside monoclonal antibody therapy. Survival data were examined on certain clinical and laboratory factors.

RESULTS

There were 57 children (32 male) treated for high-risk neuroblastoma. Their mean age was 3.9 (range 0.7-14.9) years. The median follow-up time was 5.5 (range 1.8-13.0) years for the surviving patients. There were 31 survivors, with 27 patients surviving in first remission, and the five-year overall survival and event-free survival rates were 52.5% and 47.4%, respectively. On log-rank testing, only the group of 17 patients who were exclusively treated at our centre had a survival advantage. Their five-year overall survival rate compared to patients whose initial chemotherapy was done elsewhere was 81.6% versus 41.1% (P = 0.011), and that of event-free survival was 69.7% versus 36.1% (P = 0.032). Published treatment results were obtained from four countries in Southeast Asia with five-year overall survival rates from 13.5% to 28.2%.

CONCLUSION

Intensified medical and surgical treatment for high-risk neuroblastoma proved to be effective, with superior survival rates compared to previous data from Southeast Asia.

Antibody-based immunotherapy in high-risk neuroblastoma

Although great advances have been made in the treatment of low- and intermediate-risk neuroblastoma in recent years, the prognosis for advanced disease remains poor. Therapies based on monoclonal antibodies that specifically target tumour cells have shown promise for treatment of high-risk neuroblastoma. This article reviews the use of monoclonal antibodies either as monotherapy or as part of a multifaceted treatment approach for advanced neuroblastoma, and explains how toxins, cytokines, radioactive isotopes or chemotherapeutic drugs can be conjugated to antibodies to enhance their effects. Tumour resistance, the development of blocking antibodies, and other problems hindering the effectiveness of monoclonal antibodies are also discussed. Future therapies under investigation in the area of immunotherapy for neuroblastoma are considered.

Markedly improving survival of neuroblastoma: a 30-year analysis of 1,646 patients

We sought to define current incidence trends and outcomes for pediatric patients with neuroblastoma. The SEER registry was queried from 1973 to 2002. Overall, 1,646 patients with neuroblastoma were identified. The annual incidence has remained unchanged at 0.9 per 100,000. The median age of the population was 1 year, with 42% of patients presenting at <1 year of age. The majority of tumors arose in the retroperitoneum (75.6%) with the remainder located in the mediastinum (15.3%), cervical region (6.6%) and pelvis (2.2%). Markedly improved survival has been noted in each decade (P < 0.002). Sixteen percent of lesions were over 10 cm in greatest dimension, while 84% were high-grade. Disease-specific survival at 1, 2, 5 and 20 years for the entire cohort was 81, 70, 61 and 59%, respectively. Superior survival was observed for infants <1 year of age (P < 0.001). Neuroblastomas in the mediastinum and pelvis had a better prognosis (P < 0.05) while high-grade and lesions over 10 cm carried a worse prognosis (P < 0.022). Surgery but not radiotherapy was associated with improvement in survival (P < 0.001). Multivariate analysis identified age, tumor location, stage, decade of diagnosis and surgical treatment as independent prognostic factors. Neuroblastoma remains a common malignancy with markedly improving patient outcomes. Early diagnosis and surgical therapy continue to provide the best chance for cure. More effective therapies for patients presenting over 1 year of age or those with advanced disease are still needed.

Tumor mRNA-transfected dendritic cells stimulate the generation of CTL that recognize neuroblastoma-associated antigens and kill tumor cells: immunotherapeutic implications

Several observations suggest a potential role of T-cell-mediated immunity in the control of neuroblastoma (NB). However, the generation of NB-specific cytotoxic T lymphocytes (CTL) on T-cell priming with tumor mRNA-transfected dendritic cells (DC) has never been investigated before. In the present study, the feasibility of this strategy has been analyzed, both in healthy donors and in NB patients. Monocyte-derived DC were raised from three human leukocyte antigen (HLA) A2+ NB patients and seven HLA-A1+ or HLA-A2+ healthy donors transfected with mRNA from four NB cell lines and cocultured with autologous CD8+ lymphocytes. Expanded CTL expressed an effector/memory phenotype and a T cytotoxic 1-like profile of cytokine secretion. CTL specificity was demonstrated by interferon-gamma release on incubation with HLA-matched NB cell lines. The latter cell lines, but not autologous T-cell blasts, were lysed by CTL in an HLA-restricted manner. Cytotoxicity was found to involve the release of granzyme B. When tested for reactivity against NB-associated antigens, CTL from normal individuals recognized anaplastic lymphoma-associated kinase (ALK) and preferentially expressed antigen of melanoma (PRAME) peptides only, whereas patients' CTL reacted also to survivin, telomerase, and tyrosine hydroxylase peptides. This study demonstrates that DC transfected with NB mRNA induce the generation of patients' CTL specific for different NB-associated antigens, supporting the feasibility of NB T-cell immunotherapy.

Molecular characterization of the anti-idiotypic immune response of a relapse-free neuroblastoma patient following antibody therapy: a possible vaccine against tumors of neuroectodermal origin?

Neuroblastoma treatment with chimeric antidisialoganglioside GD2 Ab ch14.18 showed objective antitumor responses. Production of anti-idiotypic Abs (Ab2) against ch14.18 (Ab1) in some cases was positively correlated with a more favorable prognosis. According to Jerne's network theory, a subset of anti-idiotypic Abs (Ab2beta) carries an "internal image" of the Ag and induces Abs (Ab3) against the original Ag. The molecular origin of an anti-idiotypic Ab response in tumor patients was not investigated previously. To clone anti-idiotypic Abs, B cells of a ch14.18-treated neuroblastoma patient with Ab2 serum reactivity were used to construct Ab phage display libraries. After repeated biopannings on ch14.18 and its murine relative, anti-GD2 mAb 14G2a, we selected 40 highly specific clones. Sequence analysis revealed at least 10 of 40 clones with different Ig genes. Identities to putative germline genes ranged between 94.90 and 100% for V(H) and between 93.90 and 99.60% for V(L). An overall high rate of replacement mutations suggested a strong Ag-driven maturation of the anti-idiotypic Abs. Two clones that were analyzed further, GK2 and GK8, inhibited binding of ch14.18 to GD2 just as the patient's serum did. GK8 alone inhibited >80% of the patient's anti-idiotypic serum Abs in binding to ch14.18. Rabbits vaccinated with GK8 or GK2 (weaker) produced Ab3 against the original target Ag GD2. GK8 may be useful as a tumor vaccine for GD2-positive [corrected] tumors.

Disseminated neuroblastoma in children older than one year at diagnosis: comparable results with three consecutive high-dose protocols adopted by the Italian Co-Operative Group for Neuroblastoma

PURPOSE

To compare the outcomes associated with modifications in three consecutive protocols employed by the Italian Co-Operative Group for Neuroblastoma (ICGNB) in disseminated neuroblastoma.

PATIENTS AND METHODS

Between January 1985 and November 1997, a total of 359 children aged 1 to 15 years with newly diagnosed stage 4 neuroblastoma were enrolled in three consecutive protocols. Compared with ICGNB-85, the ICGNB-89 protocol contained two more chemotherapy cycles, and some drugs were given at greater doses, whereas in the ICGNB-92 protocol, the induction phase included a chelating agent, and individual cycles contained four drugs instead of two.

RESULTS

A total of 330 of 359 evaluable children were included in this analysis; 106 children were treated with ICGNB-85, 65 children were treated with ICGNB-89, and 159 children were treated with ICGNB-92 protocols. Radical resection of primary tumor was carried out in 59.4%, 50.8%, and 57.9% of the patients, respectively. Major tumor response after induction therapy was achieved in 66.7%, 69.2%, and 68.6% of the patients, respectively. A total of 218 of 232 patients received consolidation therapy consisting of conventional chemotherapy in 65 patients and of high-dose chemotherapy in 153 patients. Disease recurrence or progression occurred in 82.1%, 69.2%, and 74.8% of the patients, respectively. Therapy-related deaths occurred in 1.9%, 12.3%, and 6.9% of the patients, respectively. Five-year overall survival (OS) for the three studies was 26%, 23%, and 28%, and event-free survival (EFS) was 19%, 17%, and 17%, respectively.

CONCLUSION

The therapeutic modifications adopted in the ICGNB-89 and ICGNB-92 protocols were not associated with a significant improvement in response rate or in the 5-year OS and EFS as compared with the ICGNB-85 protocol. Attempts at intensifying chemotherapy were associated with greater toxicity.

Emerging cancer-targeted therapies

There is reason to believe that the unfolding revolution in molecular biology and translational research will allow selective targeting of tumor cells, and radically change the way general practitioners and pediatric oncologists treat and follow children with cancer. This article highlights some of the most promising approaches being tested in the field. By learning about the underlying biology, the remaining hurdles, the projected timeline, and the possible impact of new therapies on the practice of pediatric oncology, health care professionals and patients should be better prepared for the future of pediatric oncology.

New approaches to hematopoietic cell transplantation in oncology

The use of high-dose chemotherapy followed by autologous HCT and the use of allogeneic HCT in children and adolescents with high-risk ALL, AML, and NBL has successfully improved outcomes. For other diseases, however, the role of HCT in treatment remains a subject of further research. The availability of HCT was significantly expanded by developing alternative graft sources that currently include BM, peripheral blood, and UCB from autologous and allogeneic related or unrelated donors. Progress in autologous HCT has been achieved by the identification of more effective and less toxic preparative regimens and by ex vivo purging of stem cell products. In allogeneic HCT, graft-versus-leukemia or graft-versus-tumor effects are being exploited increasingly to lower relapse rates. In addition, immunomodulation to promote tolerance, as well as allogeneic antitumor reactions have been achieved by antibody therapy, cytokine therapy, or cell-based immunotherapy. Future improvements are likely, as evidenced by promising preliminary results in the development of stem cell collection techniques, in vitro stem cell expansion, and purging techniques of stem cell grafts. The development of less intensive or nonmyeloablative preparative regimens may further reduce regimen-related morbidity and mortality Specific immunotherapy may facilitate tolerance induction in mismatched allogeneic HCT and support allogeneic HCT in the setting of donor-host HLA disparity. Ultimately, advances in cytokine therapy, tumor-specific vaccines, and gene therapy may decrease or even eradicate recurrence of the malignant disease after HCT.

Isolation and transplantation of highly purified autologous peripheral CD34(+) progenitor cells: purging efficacy, hematopoietic reconstitution and long-term outcome in children with high-risk neuroblastoma

We have investigated the purging efficacy of positive selection of autologous mobilized CD34(+) peripheral stem cells in 22 children with high-risk neuroblastoma. CD34(+) cell selection was performed using the method of magnetic-activated cell sorting (MACS). The median purity of the CD34(+) cells post selection was 97.6% (range 81.7-99.7). For detection of contaminating neuroblastoma cells before and after CD34(+) selection, the chimeric anti-disialoganglioside GD2 antibody delta ch 14.18 was used. Prior to positive selection, various numbers of contaminating neuroblastoma cells were found in 17 patients. After positive CD34(+) cell selection, low numbers of neuroblastoma cells were only detectable in four patients. In 18 patients, high-dose chemotherapy was performed and the isolated CD34(+) cells were reinfused. In all patients, a rapid neutrophil recovery was seen with a median time to reach 0.5 x 10(9)/l neutrophils of 12 days (range 8-24 days). Nine of the 18 patients are free of progression with a median follow-up of 55 months (range 45-70 months). Two patients are alive with relapse, six patients died due to progression or relapse and one patient died due to secondary AML 10 months after transplant while in remission from neuroblastoma. In summary, we show that, through a highly effective positive selection method, a high purging efficacy can be obtained without compromising the hematopoietic reconstitution capacity of the graft.