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Journal of Clinical Oncology recognizes that readers do not always have time to review an article in depth, and yet they still wish to understand how the results will influence their clinical practice or research. To address this need, we offer podcasts that will enhance the readership experience by presenting the key results of high-profile publications in a convenient audio format. Our podcasts are designed to place selected articles into a clinically useful perspective that is easy to listen to in the office or while on the road.

Sep 9, 2019

This JCO Podcast provides observations and commentary on the JCO article “Maintaining Outstanding Outcomes Using Response and Biology-Based Therapy for Intermediate-Risk Neuroblastoma: A Report From the Children's Oncology Group Study ANBL0531” by Twist et al. My name is Javed Khan, and I am Deputy Chief and Senior Investigator at the Genetics Branch and an Attending for the Pediatric Oncology Branch of the National Cancer Institutes of the NIH in Bethesda, Maryland. My oncologic specialty is Pediatric Hematology Oncology.

Childhood cancer is a life-threatening disease where survival rates have increased exponentially to over 75% over the past three decades. However, this has come at a considerable cost with significant incidence of late effects including hearing loss, scoliosis, hypothyroidism, growth and development delay, infertility, psychological, emotional, cognitive and neurological sequelae, and secondary malignancies. Most of these late effects have been attributed therapy including chemotherapy, surgery and radiation.

In the manuscript that accompanies this podcast, Twist et al report on the results of the Children’s Oncology Group study ANBL0531, whose primary aim was to reduce therapy for subsets of children aged <=12 years old, with intermediate-risk neuroblastoma using a biology- and response-based algorithm that assigns the length of treatment duration while maintaining a 3-year overall survival (OS) of >=95% for the entire cohort.

Neuroblastoma is an extracranial pediatric malignancy of neural crest origin that has often been described as an enigmatic cancer due to its significant clinical, molecular and biological heterogeneity. For example, some patients with widely metastatic disease are cured with minimal or no therapy whereas others have relentless progression to death despite intensive therapies.  There has been considerable progress in dissecting out the causes of this heterogeneity and developing prognostic biomarkers to stratify the risk based on several clinical, histological and molecular markers. At the time this clinical study was performed, and the manuscript written, the authors stratified patients using several clinical and biologic parameters including age, the International Neuroblastoma Staging System, MYCN amplification status, the International Neuroblastoma Pathology Classification of histopathology, and tumor DNA index. An additional marker utilized in this study was loss of heterozygosity determination of the tumors at chromosome bands 1p36 and 11q23. This stratification strategy has led to the identification of low and high-risk groups where therapy is more clearly defined and patients with low risk have excellent outcome for most patients with surgery alone and watchful waiting. For high-risk disease, significant strides have been made using a combination of surgery, aggressive chemotherapy, radiation followed by Chimeric Antibody 14.18 anti GD2 therapy, GM-CSF, IL-2 and Isotretinoin, however the five-year survival remains guarded at 40-50%. In the intermediate-risk group, the subject of this study, although the 5-year survival rates of 90-95% have been achieved, this group is significantly heterozygous raising the possibility of reducing therapy for subsets of patients within this group. This was the motivation for this study.

Thus, the goal of this clinical protocol, ANBL0531, was to refine the minimal therapy needed to achieve excellent outcomes for patients with intermediate-risk neuroblastoma, with the aim to maintain an overall 3-year OS rate of > 95% for the entire cohort. Patients were stratified into Groups 2, 3, or 4, who were assigned to receive a minimum of 2, 4, or 8 cycles of chemotherapy, respectively. Chemotherapy was identical to that used on a previous study A3961.

Reduction of therapy was planned to be achieved for patients with biologically favorable tumors (Groups 2 and 3) by using the achievement of Partial Response (PR) to chemotherapy +/- surgery to be the endpoint of therapy, rather than the achievement of Very Good Partial Response (VGPR) as was previously used on A3961. If the treatment endpoint was not achieved after completion of the scheduled chemotherapy courses, additional cycles of therapy could be administered, and patients re-evaluated following every 2 cycles to determine if the treatment endpoint has been achieved. VGPR, a more stringent response criteria, was used for Group 4 patients which includes those with age< 365 days, stage 4 disease, MYCN-not amplified, and either Unfavorable Histology (UH) or DNA Index or Ploidy (DI)=1. Patients within this subgroup received 8 cycles of chemotherapy on A3961, which was a reduction in therapy for these patients compared to prior studies. Group 4 patients also includes 2 subgroups who were previously stratified as high risk including those who had stage 3 disease, age 365- < 547days, stage 3, MYCN-NA, UH, any ploidy and also those with stage 4 disease, age 365 - < 547 days, MYCN-NA, FH, DI>1). These patients also received Isotretinoin (13-cis-retinoic acid, Accutane) for maintenance therapy, as they would have previously received this treatment on high-risk protocols. Thus, these patients would receive a significant reduction in therapy compared to prior studies.  These patients were closely monitored by interim stopping rules. Rescue therapy for this study for patients with an inadequate response to initial therapy and for patients with progressive, non-metastatic disease utilized standard cyclophosphamide and topotecan.

Reduction of therapy was also planned and achieved on their study by reducing potential surgical morbidity for patients with stage 4S disease, who would no longer be required to undergo resection of their primary tumor.

In the manuscript, the authors report that 404 evaluable patients were enrolled between 2007 and 2011, They found that compared to legacy COG studies, subsets of patients with locoregional disease, infants with stage 4 or 4S tumors, and toddlers with stage 3 or 4 disease had a reduction in treatment. The 3-year event-free survival (EFS) and OS were 83.2±1.9% and 94.9±1.1%, respectively.

Infants with stage 4 favorable biology tumors (n=61) had superior 3-year EFS compared
to patients with >= unfavorable biological feature (n=47; 86.9±4.4% versus 66.8±7.0%; p=0.02), with a trend towards OS advantage (95.0±2.8% and; 86.9±5.1% respectively p=0.08. For patients with localized disease OS was 100%.

They conclude that comparable/excellent survival was achieved with this biology- and response-based algorithm, with reduction of therapy for subsets of intermediate-risk neuroblastoma patients.

However, more effective treatment strategies are still needed for infants with unfavorable biology stage 4 disease. For the 32 infants with hyperdiploid, favorable histology (FH) stage 4 tumors with LOH at 1p36 or 11q23, or missing LOH data, intensification of treatment on ANBL0531 compared to A396110 did not reduce the risk of relapse previously reported for infants with tumors that harbor these genetic anomalies. Three-year EFS for this cohort was 68.6% (95% CI: 52.2-85.1%) versus 86.9% (95% CI: 78.3-95.4%) for stage 4 infants with favorable biology (p=0.04). Overall survival was not significantly different, indicating that many of the infants with 1p36/11q23 aberrations were successfully salvaged. Of the 20 patients who received CPM/TOPO due to an inadequate response to initial therapy, 9 achieved ≥VGPR. However, 6 of the 20 patients developed PD or relapsed, and 1 died, indicating that more effective treatment is needed for patients who do not meet the defined treatment endpoint after 8 cycles of chemotherapy.

Take home messages:

This is an important study with clinical implications for intermediate-risk neuroblastoma where the authors show that it is possible to reduce therapy based on a clinical Partial Response (PR) endpoint compared to Very Good Partial Response (VGPR). This most likely reflects the biology of the disease such that tumors that are responding to therapy will continue to involute. However, more effective therapy is needed for those patients who develop progressive disease (PD) or relapse or do not meet the defined treatment endpoint after 8 cycles of chemotherapy as these patients continue to have poor outcome.

This will await the result of current biological and genomic studies and the development of novel therapies targeting ALK or RAS, or epigenetic targeting of MYC or MYCN activated tumors, or immunotherapeutic approaches such as adoptive cell therapies consisting of chimeric antigen receptor (CAR T cell) or, NK cells, or the use of immunocytokines such as hu14.18-IL2 or antibody drug conjugates. All these holds promise for future sub-stratification and new therapies for children with intermediate and high-risk neuroblastoma.

This concludes this JCO Podcast. Thank you for listening.