Children's Oncology Group's 2023 blueprint for research: Bone tumors.

The Children's Oncology Group (COG) Bone Tumor Committee is responsible for clinical trials and biological research on localized, metastatic, and recurrent osteosarcoma and Ewing sarcoma (EWS). Results of clinical trials in localized disease completed and published in the past 10 years have led to international standard-of-care chemotherapy for osteosarcoma and EWS. A recent focus on identifying disease subgroups has led to the identification of biological features associated with poor outcomes including the presence of circulating tumor DNA (ctDNA) at diagnosis, and specific genomic alterations-MYC amplification for osteosarcoma and STAG2 and TP53 mutation for EWS. Studies validating these potential biomarkers are under way. Clinical trials evaluating the addition of multitargeted kinase inhibitors, which are active in relapsed bone sarcomas, to standard chemotherapy are under way in osteosarcoma and planned in EWS. In addition, the Committee has data analyses and a clinical trial under way to evaluate approaches to local management of the primary tumor and metastatic sites. Given the rarity of bone sarcomas, we have prioritized international interactions and are in the process of forming an international data-sharing consortium to facilitate refinement of risk stratification and study of rare disease subtypes.

Bad to the Bone: Emerging Approaches to Aggressive Bone Sarcomas.

Bone sarcomas are rare heterogeneous tumors that affect patients of all ages including children, adolescent young adults, and older adults. They include many aggressive subtypes and patient groups with poor outcomes, poor access to clinical trials, and lack of defined standard therapeutic strategies. Conventional chondrosarcoma remains a surgical disease, with no defined role for cytotoxic therapy and no approved targeted systemic therapies. Here, we discuss promising novel targets and strategies undergoing evaluation in clinical trials. Multiagent chemotherapy has greatly improved outcomes for patients with Ewing sarcoma (ES) and osteosarcoma, but management of those with high-risk or recurrent disease remains challenging and controversial. We describe the impact of international collaborative trials, such as the rEECur study, that aim to define optimal treatment strategies for those with recurrent, refractory ES, and evidence for high-dose chemotherapy with stem-cell support. We also discuss current and emerging strategies for other small round cell sarcomas, such as CIC-rearranged, BCOR-rearranged tumors, and the evaluation of emerging novel therapeutics and trial designs that may offer a new paradigm to improve survival in these aggressive tumors with notoriously bad (to the bone) outcomes.

Data standards in pediatric oncology: Past, present, and future.

In this commentary, we highlight the central role that data standards play in facilitating data-driven efforts to advance research in pediatric oncology. We discuss the current state of data standards for pediatric oncology and propose five steps to achieve an improved future state with benefits for clinicians, researchers, and patients.

Association of BRAF V600E mutations with vasoactive intestinal peptide syndrome in MYCN-amplified neuroblastoma.

Very rarely, vasoactive intestinal peptide-related diarrhea (VIP-D) is observed in patients with high-risk neuroblastoma (HR-NB) where the associated fluid and electrolyte abnormalities can pose a major clinical challenge for administering the required aggressive multimodality treatment. Two patients with HR-NB developed VIP-D during induction and were found to have a somatic BRAF V600E mutation. Serum VIP levels and diarrhea promptly resolved in both patients after initiating treatment with BRAF and MEK inhibitors. This illustrates an association of VIP-D with BRAF V600E mutations and demonstrates a therapeutic strategy in the specific context of VIP-D and BRAF V600E mutations in HR-NB patients. The addition of BRAF and MEK inhibitors allows continued conventional tumor-directed treatment by decreasing the severity of symptoms caused by this life-threatening complication.

Birth Characteristics and Risk of Early-Onset Synovial Sarcoma.

BACKGROUND: Synovial sarcoma is a rare cancer with peak incidence in the young adult period. Despite poor outcomes of this aggressive cancer, there is little epidemiologic research addressing its etiology. METHODS: We collected birth characteristic data on synovial sarcoma cases born during 1978-2015 and diagnosed during 1988-2015 in California (n = 244), and 12,200 controls frequency-matched on year of birth. We also constructed a dataset of cancer cases in siblings of sarcoma subjects to assess familial risk. RESULTS: In multivariable logistic regression analyses, synovial sarcoma was more frequent in Hispanics compared with non-Hispanic whites [OR, 1.48; 95% confidence interval (CI), 1.06-2.08]. Higher birth weight was a risk factor in Hispanics; each 500 g increase in birth weight was associated with a 22% increase in disease risk (OR, 1.22; 95% CI, 1.00-1.48). Also, a strong role for birth order was suggested, with highest risk for the first born (second child compared with first: OR, 0.61; 95% CI, 0.44-0.84; third or later compared with first: OR, 0.53; 95% CI, 0.36-0.77). Siblings of patients with synovial sarcoma did not display elevated cancer incidence, suggesting the low likelihood that strong familial predisposition alleles play a significant role in this disease. CONCLUSIONS: The associations with birth weight and birth order suggest that nutritional, developmental, and environmental factors may play a role in the etiology of synovial sarcoma. IMPACT: Further epidemiologic research on synovial sarcoma should evaluate epigenetic and developmental mechanisms and the formation of the archetypical t(X;18) translocation that defines this disease.

Congenital neuroglial choristoma of the foot.

Neuroglial choristomas are rare malformations of heterotopic neural tissue that have been previously reported predominantly in the head and neck. Competing theories of embryogenesis propose their origin as encephaloceles that have undergone resorption of their cranial connection or displaced neuroectodermal cells which have undergone ectopic proliferation. Most cases occur in midline or para-midline structures. There have been no prior published cases of a neuroglial choristoma in the extremities. We present a case of a 13-month-old otherwise healthy child who presented to our institution with a slowly growing foot mass who was found to have a neuroglial choristoma. This case suggests an early embryological migration defect as the etiology and offers a unique differential consideration for a benign extremity mass.

Successful autologous cord blood transplantation in a child with acquired severe aplastic anemia.

Over 400 cases of pediatric SAA occur annually in the United States. A growing number of children with SAA may have had their stem cells harvested through cord blood collection. We describe a nine-yr-old male with SAA treated successfully with an autologous cord blood transplant following immunoablative chemotherapy. With the increasing number of people cryopreserving autologous cord blood, the use of autologous cord blood in the treatment of SAA might be considered as initial therapy. This case serves to discuss approaches to preparative therapy as well as the potential complications in this growing cohort of patients.

The Wnt signaling pathway: implications for therapy in osteosarcoma.

Osteosarcoma is the most common primary bone malignancy, with a high propensity for local invasion, early metastasis and relapse. While the molecular mechanisms behind osteosarcoma development and metastasis have not yet been fully elucidated, research has highlighted an important role for Wnt signaling. Several Wnt ligands, receptors and coreceptors are highly expressed in osteosarcoma cell lines, while Wnt inhibitors are downregulated. As a result, research has begun to identify mechanisms with which to inhibit Wnt signaling. The use of Wnt pathway inhibitors and the targeting of c-Met, a Wnt regulated proto-oncogene, may be two possible mechanisms for treatment of osteosarcoma. In addition, as the Wnt signaling pathway is a regulator of stem cells, reagents that function as Wnt inhibitors are currently under investigation as inhibitors of cancer stem cell proliferation. Research involving the Wnt signaling pathway and cancer stem cells holds promise for novel treatment options in the future.

Wnt inhibitory factor 1 decreases tumorigenesis and metastasis in osteosarcoma.

It has been reported that the progression of osteosarcoma was closely associated with the aberrant activation of canonical Wnt signaling. Wnt inhibitory factor-1 (WIF-1) is a secreted Wnt inhibitor whose role in human osteosarcoma remains unknown. In this study, WIF-1 expression in NHOst and osteosarcoma cell lines was determined by real-time reverse transcription-PCR, methylation-specific PCR, and Western blotting analysis. In addition, tissue array from patient samples was examined for WIF-1 expression by immunohistochemistry. Compared with normal human osteoblasts, WIF-1 mRNA and protein levels were significantly downregulated in several osteosarcoma cell lines. The downregulation of WIF-1 mRNA expression is associated with its promoter hypermethylation in these tested cell lines. Importantly, WIF-1 expression was also downregulated in 76% of examined osteosarcoma cases. These results suggest that the downregulation of WIF-1 expression plays a role in osteosarcoma progression. To further study the potential tumor suppressor function of WIF-1 in osteosarcoma, we established stable 143B cell lines overexpressing WIF-1. WIF-1 overexpression significantly decreased tumor growth rate in nude mice as examined by the s.c. injection of 143B cells stably transfected with WIF-1 and vector control. WIF-1 overexpression also markedly reduced the number of lung metastasis in vivo in an orthotopic mouse model of osteosarcoma. Together, these data suggest that WIF-1 exerts potent antiosteosarcoma effect in vivo in mouse models. Therefore, the reexpression of WIF-1 in WIF-1-deficient osteosarcoma represents a potential novel treatment and preventive strategy.

Dominant negative LRP5 decreases tumorigenicity and metastasis of osteosarcoma in an animal model.

Osteosarcoma (OS) is a primary malignant bone tumor with a high propensity for local recurrence and distant metastasis. We previously showed a secreted, dominant-negative LRP5 receptor (DNLRP5) suppressed in vitro migration and invasion of the OS cell line SaOS-2. Therefore, we hypothesized DNLRP5 also has in vivo antitumor activity against OS. We used the 143B cell line as a model to study the effect of DNLRP5 by stable transfection. Inhibition of Wnt signaling by DNLRP5 was verified by a reduction in TOPFLASH luciferase activity. In soft agar, DNLRP5-transfected 143B cells formed fewer and smaller colonies than control transfected cells. DNLRP5 transfection reduced in vivo tumor growth of 143B cells in nude mice. DNLRP5 also decreased in vitro cellular motility in a scratch wound assay. In a spontaneous pulmonary metastasis model, DNLRP5 reduced both the size and number of lung metastatic nodules. The reduction in cellular invasiveness by DNLRP5 was associated with decreased expression of matrix metalloproteinase-2, N-cadherin, and Snail. Our data suggest canonical Wnt/LRP5 signaling reflects an important underlying mechanism of OS progression. Therefore, strategies to suppress LRP5-mediated signaling in OS cells may lead to a reduction in local or systemic disease burden.

Frzb, a secreted Wnt antagonist, decreases growth and invasiveness of fibrosarcoma cells associated with inhibition of Met signaling.

Soft tissue sarcomas (STS) have a strong propensity for aggressive growth and metastasis. We showed that the secreted Wnt antagonist Frzb exhibited potent antitumor activity against prostate cancer, an epithelial type of malignancy. In this study, we further showed the antitumor efficacy of Frzb in STS, a mesenchymal group of cancer. Frzb transfection of HT1080 (fibrosarcoma) and SW872 (liposarcoma) cell lines and their conditioned media resulted in a significant reduction in cellular invasion, motility, and colony formation in soft agar compared with vector control-transfected cells. In a xenograft mouse model, Frzb dramatically suppressed tumor growth of HT1080 cells in nude mice. In a tail-vein injection metastatic model, Frzb-transfected HT1080 cells formed fewer and smaller lung nodules than vector control cells. In addition, we identified new mechanisms for Frzb antitumor activities. Frzb reduced c-Met expression and inhibited Met-mediated signaling, associated with up-regulation of epithelial markers (i.e., keratins 8 and 18) and down-regulation of mesenchymal markers (i.e., vimentin, N-cadherin, fibronectin, Slug, and Twist). Similar to Frzb, silencing of c-Met by short hairpin RNA or using a dominant-negative LRP5 receptor also suppressed Met signaling, leading to reduced cellular motility, invasion, and in vivo tumor growth. Given recent studies indicating an important role of c-Met in sarcoma development and progression, our data showed that Frzb expression was significantly inversely correlated with Met expression in both STS cell lines and tissues. These results suggested the usefulness of Frzb in modulating Met signaling as a new treatment strategy for STS.