Analysis of receptor tyrosine kinases (RTKs) and downstream pathways in chordomas

Treatment of Clival Chordomas: A 20-Year Experience and Systematic Literature Review

Clival chordomas are rare but aggressive skull base tumors that pose significant treatment challenges and portend dismal prognosis. The aim of this study was to highlight the advantages and limitations of available treatments, to furnish prognostic indicators, and to shed light on novel therapeutic strategies. We conducted a retrospective study of clival chordomas that were surgically treated at our institution from 2003 to 2022; for comparison purposes, we provided a systematic review of published surgical series and, finally, we reviewed the most recent advancements in molecular research. A total of 42 patients underwent 85 surgeries; median follow-up was 15.8 years, overall survival rate was 49.9% at 10 years; meanwhile, progression-free survival was 26.6% at 10 years. A significantly improved survival was observed in younger patients (<50 years), in tumors with Ki67 ≤ 5% and when adjuvant radiotherapy was performed. To conclude, clival chordomas are aggressive tumors in which surgery and radiotherapy play a fundamental role while molecular targeted drugs still have an ancillary position. Recognizing risk factors for recurrence and performing a molecular characterization of more aggressive lesions may be the key to future effective treatment.

Shedding light on emerging therapeutic targets for chordoma

INTRODUCTION

Despite encouraging advances in radiation and surgical treatment, chordomas remain resistant to chemotherapy and local recurrence is common. Although the primary mechanism of recurrence is local, metastatic disease occurs in a small subset of patients. Recurrence may also occur along the surgical trajectory if care is not taken to fully excise the open biopsy pathway. There is increasing morbidity with reoperation upon disease recurrence, and radiation is an option for cytoreduction in primary disease or for recurrent disease, although toxicity may be observed with high-dose therapies. Given these challenges, targeted chemotherapeutic agents for postoperative adjuvant treatment are needed.

AREAS COVERED

In this review, we summarize the genetic drivers of chordoma and the state of the current research in chordoma immunotherapy and epigenetics.

EXPERT OPINION

Chordoma is a heterogenous tumor that should be targeted from different angles and the study of its characteristics, from molecular to immunological to epigenetic, is necessary. Combining different approaches, such as studying noninvasive patient methylation patterns with tissue-based molecular and drug screening, can transform patient care by guiding treatment decisions based on prognostic mechanisms from different sources, while helping individualize surgical planning and treatment.

Mapping the landscape of genetic dependencies in chordoma

Identifying the spectrum of genes required for cancer cell survival can reveal essential cancer circuitry and therapeutic targets, but such a map remains incomplete for many cancer types. We apply genome-scale CRISPR-Cas9 loss-of-function screens to map the landscape of selectively essential genes in chordoma, a bone cancer with few validated targets. This approach confirms a known chordoma dependency, TBXT (T; brachyury), and identifies a range of additional dependencies, including PTPN11, ADAR, PRKRA, LUC7L2, SRRM2, SLC2A1, SLC7A5, FANCM, and THAP1. CDK6, SOX9, and EGFR, genes previously implicated in chordoma biology, are also recovered. We find genomic and transcriptomic features that predict specific dependencies, including interferon-stimulated gene expression, which correlates with ADAR dependence and is elevated in chordoma. Validating the therapeutic relevance of dependencies, small-molecule inhibitors of SHP2, encoded by PTPN11, have potent preclinical efficacy against chordoma. Our results generate an emerging map of chordoma dependencies to enable biological and therapeutic hypotheses.

Prognostic Relevance and In Vitro Targeting of Concomitant PTEN and p16 Deficiency in Chordomas

Chordomas are rare bone tumors arising along the spine. Due to high resistance towards chemotherapy, surgical resection—often followed by radiation therapy—is currently the gold standard of treatment. So far, targeted systemic therapies have not been approved. The most frequent molecular alterations include the loss of PTEN and CDKN2A (encoding p16), being associated with poor prognoses in chordoma patients. Specific inhibitors of the PI3K/AKT/mTOR pathway as well as CDK4/6 have shown antitumor activity in preclinical studies and have recently been under investigation in phase II clinical trials; however, the clinical impacts and therapeutic consequences of concomitant PTEN and p16 deficiency have not yet been investigated in chordomas. In a cohort of 43 chordoma patients, 16% of the cases were immunohistochemically negative for both markers. The simultaneous loss of PTEN and p16 was associated with a higher KI-67 index, a tendency to metastasize, and significantly shorter overall survival. Additionally, 30% of chordoma cell lines (n = 19) were PTEN-/p16-negative. Treating these chordoma cells with palbociclib (CDK4/6 inhibitor), rapamycin (mTOR inhibitor) or the pan-PI3K inhibitor buparlisib significantly reduced cell viability. Synergistic effects were observed when combining palbociclib with rapamycin. In conclusion, we show that patients with PTEN-/p16-negative chordomas have poor prognoses and provide strong preclinical evidence that these patients might benefit from a Palbociclib/rapamycin combination treatment.

Receptor Tyrosine Kinase Inhibitors for the Treatment of Recurrent and Unresectable Bone Sarcomas

Bone sarcomas are a heterogeneous group of rare tumors with a predominance in the young population. Few options of systemic treatment are available once they become unresectable and resistant to conventional chemotherapy. A better knowledge of the key role that tyrosine kinase receptors (VEGFR, RET, MET, AXL, PDGFR, KIT, FGFR, IGF-1R) may play in the pathogenesis of these tumors has led to the development of multi-target inhibitors (TKIs) that are progressively being incorporated into our therapeutic arsenal. Osteosarcoma (OS) is the most frequent primary bone tumor and several TKIs have demonstrated clinical benefit in phase II clinical trials (cabozantinib, regorafenib, apatinib, sorafenib, and lenvatinib). Although the development of TKIs for other primary bone tumors is less advanced, preclinical data and early trials have begun to show their potential benefit in advanced Ewing sarcoma (ES) and rarer bone tumors (chondrosarcoma, chordoma, giant cell tumor of bone, and undifferentiated pleomorphic sarcoma). Previous reviews have mainly provided information on TKIs for OS and ES. We aim to summarize the existing knowledge regarding the use of TKIs in all bone sarcomas including the most recent studies as well as the potential synergistic effects of their combination with other systemic therapies.

Emerging target discovery and drug repurposing opportunities in chordoma

The development of effective and personalized treatment options for patients with rare cancers like chordoma is hampered by numerous challenges. Biomarker-guided repurposing of therapies approved in other indications remains the fastest path to redefining the treatment paradigm, but chordoma's low mutation burden limits the impact of genomics in target discovery and precision oncology efforts. As our knowledge of oncogenic mechanisms across various malignancies has matured, it's become increasingly clear that numerous properties of tumors transcend their genomes - leading to new and uncharted frontiers of therapeutic opportunity. In this review, we discuss how the implementation of cutting-edge tools and approaches is opening new windows into chordoma's vulnerabilities. We also note how a convergence of emerging observations in chordoma and other cancers is leading to the identification and evaluation of new therapeutic hypotheses for this rare cancer.

Selinexor inhibits growth of patient derived chordomas in vivo as a single agent and in combination with abemaciclib through diverse mechanisms

Chordoma is a rare cancer that grows in the base of the skull and along the mobile spine from remnants of embryonic notochord tissue. The cornerstone of current treatments is surgical excision with adjuvant radiation therapy, although complete surgical removal is not always possible. Chordomas have high rates of metastasis and recurrence, with no approved targeted agents. Selinexor and eltanexor are selective inhibitors of nuclear export (SINE) that prevent the karyopherin protein exportin-1 (XPO1) from shuttling its cargo proteins through nuclear pore complexes out of the nucleus and into the cytoplasm. As cancer cells overexpress XPO1, and many of its cargos include tumor suppressor proteins and complexes bound to oncogene mRNAs, XPO1 inhibition can suppress oncogene translation and restore tumor suppressor protein activity in different cancer types. SINE compounds have exhibited anti-cancer activity in a wide range of hematological and solid tumor malignancies. Here we demonstrate the preclinical effectiveness of SINE compounds used as single agents or in combination with either the proteasome inhibitor, bortezomib, or the CDK4/6 inhibitor, abemaciclib, against various patient- derived xenograft (PDX) mouse models of chordoma, which included clival and sacral chordomas from adult or pediatric patients with either primary or metastatic disease, with either differentiated or poorly differentiated subtypes. SINE treatment significantly impaired tumor growth in all five tested chordoma models, with the selinexor and abemaciclib combination showing the strongest activity (tumor growth inhibition of 78-92%). Immunohistochemistry analysis of excised tumors revealed that selinexor treatment resulted in marked induction of apoptosis and reduced cell proliferation, as well as nuclear accumulation of SMAD4, and reduction of Brachyury and YAP1. RNA sequencing showed selinexor treatment resulted in differences in activated and repressed signaling pathways between the PDX models, including changes in WNT signaling, E2F pathways and glucocorticoid receptor signaling. This is consistent with SINE-compound mediated XPO1 inhibition exhibiting anti-cancer activity through a broad range of different mechanisms in different molecular chordoma subsets. Our findings validate the need for further investigation into selinexor as a targeted therapeutic for chordoma, especially in combination with abemaciclib.

Targeted Inhibition of O-Linked β-N-Acetylglucosamine Transferase as a Promising Therapeutic Strategy to Restore Chemosensitivity and Attenuate Aggressive Tumor Traits in Chemoresistant Urothelial Carcinoma of the Bladder

Acquisition of acquired chemoresistance during treatment cycles in urothelial carcinoma of the bladder (UCB) is the major cause of death through enhancing the risk of cancer progression and metastasis. Elevated glucose flux through the abnormal upregulation of O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) controls key signaling and metabolic pathways regulating diverse cancer cell phenotypes. This study showed that OGT expression levels in two human UCB cell models with acquired resistance to gemcitabine and paclitaxel were significantly upregulated compared with those in parental cells. Reducing hyper-O-GlcNAcylation by OGT knockdown (KD) markedly facilitated chemosensitivity to the corresponding chemotherapeutics in both cells, and combination treatment with OGT-KD showed more severe growth defects in chemoresistant sublines. We subsequently verified the suppressive effects of OGT-KD monotherapy on cell migration/invasion in vitro and xenograft tumor growth in vivo in chemoresistant UCB cells. Transcriptome analysis of these cells revealed 97 upregulated genes, which were enriched in multiple oncogenic pathways. Our final choice of suspected OGT glycosylation substrate was VCAN, S1PR3, PDGFRB, and PRKCG, the knockdown of which induced cell growth defects. These findings demonstrate the vital role of dysregulated OGT activity and hyper-O-GlcNAcylation in modulating treatment failure and tumor aggression in chemoresistant UCB.

Targeted delivery of cancer drug paclitaxel to chordomas tumor cells via an RNA nanoparticle harboring an EGFR aptamer

Paclitaxel has been extensively used in clinics for cancer treatment. However, its limited solubility in aqueous solution and high occurrence of side effects have also been widely reported. In this study, we constructed a biocompatible RNA nanoparticle delivery system (3WJ-EGFR_apt) that includes 3WJ (3-way junction) nanoparticle with a size of 4.85 ± 0.59 nm as a backbone and an EGFR (epidermal growth factor receptor) aptamer for specific targeting to chordomas cells, which owns the encapsulation ability of drug paclitaxel (PTX) for cancer therapy. Confocal microscopy and flow cytometry results confirmed 3WJ-EGFR_apt nanoparticle exhibited excellent specific targeting to chordomas cell U-CH2 which is an EGFR(+) cell line; while the 3WJ nanoparticle lose the targeted ability. Both of the two nanoparticles own no sensitivity to lung cancer cell H520 which is an EGFR(-) cell line. Moreover, the 3WJ-EGFR_apt nanoparticle encapsulated drug PTX could enhance the inhibition efficiency of chordomas tumor cells U-CH2 as compared to free PTX alone. This work demonstrates that RNA-3WJ constructed with a targeting aptamer provides a compromising targeted drug delivery ability on chordomas cells for therapeutics.

Advancement of PI3 Kinase Inhibitor Combination Therapies for PI3K-Aberrant Chordoma

Objectives  Targeted inhibitors of the PI3 kinase (PI3K) pathway have shown promising but incomplete antitumor activity in preclinical chordoma models. The aim of this study is to advance methodology for a high-throughput drug screen using chordoma models to identify new combination therapies for chordoma. Study Design  Present work is an in vitro study. Setting  The study conducted at an academic research laboratory. Materials and Methods  An in vitro study on automated high-throughput screening of chordoma cells was performed using a library of 1,406 drugs as both mono- and combination therapies with PI3K inhibitors. Combination indices were determined for dual therapies and synergistic outliers were identified as potential therapeutic agents. T (brachyury) siRNA knockdown in combination with PI3K pathway inhibition was also assessed. Results  Fifty-nine combination therapies were identified as having potential therapeutic efficacy. Effective combinations included PI3K inhibitors with GSK1838705A (ALK/IGF-1R inhibitor), LY2874455 (VEGFR/FGFR inhibitor), El1 (selective Ezh2 inhibitor), and (-)-p-bromotetramisole oxalate (alkaline phosphatase inhibitor). The top ranking targets identified included ALK, PDGFR, VEGFR, aurora kinase, and BCL-2. T (brachyury) inhibition produced significant reduction in cell viability and growth; however PI3K inhibition in combination with T (brachyury) knockdown did not result in further reduction in growth and viability in vitro. Conclusion  High throughput with in vitro combination screening is feasible with chordoma cells and allows for rapid identification of synergistic dual-therapies. Potential combination therapies and targetable pathways were identified. T (brachyury) knockdown produced significant reduction in cell viability, but did not show additional benefit with PI3K pathway inhibition in this model. Further in vitro and in vivo validation of these therapeutic combinations is warranted.

Endoscopic endonasal approach for loco-regional recurrent clivus chordomas

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EEA represents an ideal approach for loco-regional recurrent CCs.

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EEA is well tolerated, with preservation of patients QoL.

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EEA can be considered for patients with perspectives of adjuvant therapies.

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Otherwise, EEA can be considered only in selected cases with a palliative aim.

Multivariate Analysis and Validation of the Prognostic Factors for Skull Base Chordoma

Background: Skull base chordoma is a rare tumor with low-grade malignancy and a high recurrence rate, the factors affecting the prognosis of patients need to be further studied. For that, we investigated prognostic factors of skull base chordoma through the database of the Surveillance, Epidemiology, and End Results (SEER) program, and validated in an independent data set from the Xiangya Hospital.

Methods: Six hundred and forty-three patients diagnosed with skull base chordoma were obtained from the SEER database (606 patients) and the Xiangya Hospital (37 patients). Categorical variables were selected by Chi-square test with a statistical difference. Survival curves were constructed by Kaplan–Meier analysis and compared by log-rank test. Univariate and multivariate Cox regression analyses were used to explore the prognostic factors. Propensity score matching (PSM) analysis was undertaken to reduce the substantial bias between gross total resection (GTR) and subtotal resection (STR) groups. Furthermore, clinical data of 37 patients from the Xiangya Hospital were used as validation cohorts to check the survival impacts of the extent of resection and adjuvant radiotherapy on prognosis.

Results: We found that age at diagnosis, primary site, disease stage, surgical treatment, and tumor size was significantly associated with the prognosis of skull base chordoma. PSM analysis revealed that there was no significant difference in the OS between GTR and STR (p = 0.157). Independent data set from the Xiangya Hospital proved no statistical difference in OS between GTR and STR groups (p = 0.16), but the GTR group was superior to the STR group for progression-free survival (PFS) (p = 0.048). Postoperative radiotherapy does not improve OS (p = 0.28), but it can prolong PFS (p = 0.0037). Nomograms predicting 5- and 10-year OS and DSS were constructed based on statistically significant factors identified by multivariate Cox analysis. Age, primary site, tumor size, surgical treatment, and disease stage were included as prognostic predictors in the nomograms with good performance.

Conclusions: We identified age, tumor size, surgery, primary site, and tumor stage as main factors affecting the prognosis of the skull base chordoma. Resection of the tumor as much as possible while ensuring safety, combined with postoperative radiotherapy may be the optimum treatment for skull base chordoma.

Discovery and structure - activity relationship exploration of pyrazolo[1,5-a]pyrimidine derivatives as potent FLT3-ITD inhibitors

Internal tandem duplications of FLT3 (FLT3-ITD) occur in approximately 25% of all acute myeloid leukemia (AML) cases and confer a poor prognosis. Optimization of the screening hit 1 from our in-house compound library led to the discovery of a series of pyrazolo[1,5-a]pyrimidine derivatives as potent and selective FLT3-ITD inhibitors. Compounds 17 and 19 displayed potent FLT3-ITD activities both with IC₅₀ values of 0.4 nM and excellent antiproliferative activities against AML cell lines. Especially, compounds 17 and 19 inhibited the quizartinib resistance- conferring mutations, FLT3^D835Y, both with IC₅₀ values of 0.3 nM. Moreover, western blot analysis indicated that compounds 17 and 19 potently inhibited the phosphorylation of FLT3 and attenuated downstream signaling in AML cells. These results indicated that pyrazolo[1,5-a]pyrimidine derivatives could be promising FLT3-ITD inhibitors for the treatment AML.

AZD8055 enhances in vivo efficacy of afatinib in chordomas

Chordomas are primary bone tumors that arise in the cranial base, mobile spine, and sacrococcygeal region, affecting patients of all ages. Currently, there are no approved agents for chordoma patients. Here, we evaluated the anti-tumor efficacy of small molecule inhibitors that target oncogenic pathways in chordoma, as single agents and in combination, to identify novel therapeutic approaches with the greatest translational potential. A panel of small molecule compounds was screened in vivo against patient-derived xenograft (PDX) models of chordoma, and potentially synergistic combinations were further evaluated using chordoma cell lines and xenograft models. Among the tested agents, inhibitors of EGFR (BIBX 1382, erlotinib, and afatinib), c-MET (crizotinib), and mTOR (AZD8055) significantly inhibited tumor growth in vivo but did not induce tumor regression. Co-inhibition of EGFR and c-MET using erlotinib and crizotinib synergistically reduced cell viability in chordoma cell lines but did not result in enhanced in vivo activity. Co-inhibition of EGFR and mTOR pathways using afatinib and AZD8055 synergistically reduced cell viability in chordoma cell lines. Importantly, this dual inhibition completely suppressed tumor growth in vivo, showing improved tumor control. Together, these data demonstrate that individual inhibitors of EGFR, c-MET, and mTOR pathways suppress chordoma growth both in vitro and in vivo. mTOR inhibition increased the efficacy of EGFR inhibition on chordoma growth in several preclinical models. The insights gained from our study potentially provide a novel combination therapeutic strategy for patients with chordoma. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Biological Treatments of Neurofibromatosis Type 2 and Other Skull Base Disorders

Studies of genomic alterations that occur in skull base tumors have provided information regarding biological aberrations that are necessary for the growth and maintenance of these tumors. This has led to the development and initiation of clinical trials incorporating biological treatments for many skull base tumors. The exciting developments of molecularly targeted therapy for the treatment of skull base tumors may provide noninvasive therapeutic options for patients that can be used either alone or in combination with surgery and/or radiation therapy. Future analysis and continued scientific discovery of treatments for skull base tumors can lead to improved outcomes in patients.

Knockdown of TMED3 inhibits cell viability and migration and increases apoptosis in human chordoma cells

Chordoma is a rare low‑grade tumor of the axial skeleton. Over previous decades, a range of targeted drugs have been used for treating chordoma, with more specific and effective therapies under investigation. Transmembrane Emp24 protein transport domain containing 3 (TMED3) is a novel gene reported to be a regulator of oncogenesis, cancer development and metastasis; however, its role in chordoma remains unclear. In the present study, the expression of TMED3 was investigated in chordoma cells, and the effect of TMED3 knockdown on chordoma development was examined in vitro and in vivo, followed by exploration of differentially expressed proteins in TMED3‑silenced chordoma cells via an apoptosis antibody array. Reverse transcription‑quantitative PCR and western blot assays were performed to determine the expression levels. It was revealed that TMED3 was highly expressed in chordoma, and that knockdown of TMED3 inhibited cell viability and migration, and enhanced the apoptosis of chordoma cells. Additionally, knockdown of TMED3 inhibited the expression of Bcl‑2, heat shock protein 27, insulin‑like growth factor (IGF)‑I, IGF‑II, IGF binding protein‑2, Livin, Akt, CDK6 and cyclin D1 proteins, whereas MAPK9 was upregulated. Furthermore, a xenograft nude mice model demonstrated that TMED3 expression promoted tumor growth. Collectively, the present findings suggested that knockdown of TMED3 inhibited cell viability and migration, and enhanced apoptosis in chordoma cells, and that TMED3 may be a novel target for chordoma therapy.

Ependymoma and Chordoma

Ependymoma and chordoma are 2 tumors that occur throughout the craniospinal axis, and for which the extent of neurosurgical resection has a key prognostic role. Both tumors have distinctive pathologic features, yet can present significant diagnostic challenges to pathologists in cases without classical histology. The molecular understanding of ependymoma has had significant advances in the past decade, with the identification of 9 molecular groups with significant prognostic and clinical implications, while a comprehensive study of chordoma further emphasized the key role of brachyury overexpression in its pathogenesis. In this review, we discuss the pathogenesis, radiology and gross pathology, histology, and molecular features of these 2 tumors, as well as active research into targeted therapies, with an emphasis on practical diagnostic challenges, and the use of immunohistochemical and molecular tests in routine diagnostic practice.

Prognostic Value of Cumulative Score Based on Preoperative Fibrinogen and Albumin Level in Skull Base Chordoma

Objective

Inflammation and malnutrition have been shown to be correlated with tumor progression and a poor prognosis in various cancers. However, the clinical implications of biomarkers of inflammation and malnutrition in chordoma have not been elucidated. We attempted to characterize the fibrinogen and albumin levels in skull base chordoma and investigate their correlations with clinicopathological data and survival.

Methods

The preoperative levels of fibrinogen and albumin were assessed in 183 primary skull base chordoma patients. The cutoff values were determined by X-tile software, and their correlations with patient prognosis were further explored using the Kaplan–Meier curve and Cox proportional hazards regression analysis. In addition, the predictive performances of these markers in survival were evaluated by receiver operating characteristic curves.

Results

The values of fibrinogen and albumin in skull base chordoma patients ranged from 1.73 to 7.40 and 37.6 to 53.0 g/L, respectively. The optimal cutoff values for fibrinogen and albumin were 3.29 and 44.60 g/L, respectively. Fibrinogen and albumin were correlated with the patient age and tumor pathology types. Albumin, but not fibrinogen, was associated with the patients’ progression-free survival and overall survival. Importantly, the FA score, which combines fibrinogen and albumin, could independently predict both progression-free survival and overall survival, and enhanced the performance of fibrinogen or albumin in survival prediction in skull base chordoma.

Conclusion

Our data reveal the clinical prognostic role of albumin and suggest that the FA score may be a valuable prognostic grading system in skull base chordoma.

Small-Molecule Fms-like Tyrosine Kinase 3 Inhibitors: An Attractive and Efficient Method for the Treatment of Acute Myeloid Leukemia

Fms-like tyrosine kinase 3 (FLT3) is an important member of the class III receptor tyrosine kinase (RTK) family, which is involved in the proliferation of hematopoietic cells and lymphocytes. In recent years, increasing evidence have demonstrated that the activation and mutation of FLT3 is closely implicated in the occurrence and development of acute myeloid leukemia (AML). The exploration of small-molecule inhibitors targeting FLT3 has aroused wide interest of pharmaceutical chemists and is expected to bring new hope for AML therapy. In this review, we specifically highlighted FLT3 mediated JAK/STAT, RAS/MAPK, and PI3K/AKT/mTOR signaling. The structural properties and biological activities of representative FLT3 inhibitors reported from 2014 to the present were also summarized. In addition, the major challenges in the current advance of novel FLT3 inhibitors were further analyzed, with the aim to guide future drug discovery.

The ubiquitin system: orchestrating cellular signals in non-small-cell lung cancer

The ubiquitin system, known as a common feature in eukaryotes, participates in multiple cellular processes, such as signal transduction, cell-cycle progression, receptor trafficking and endocytosis, and even the immune response. In lung cancer, evidence has revealed that aberrant events in ubiquitin-mediated processes can cause a variety of pathological outcomes including tumorigenesis and metastasis. Likewise, ubiquitination on the core components contributing to the activity of cell signaling controls bio-signal turnover and cell final destination. Given this, inhibitors targeting the ubiquitin system have been developed for lung cancer therapies and have shown great prospects for clinical application. However, the exact biological effects and physiological role of the drugs used in lung cancer therapies are still not clearly elucidated, which might seriously impede the progress of treatment. In this work, we summarize current research advances in cell signal regulation processes mediated through the ubiquitin system during the development of lung cancer, with the hope of improving the therapeutic effects by means of aiming at efficient targets.

Active receptor tyrosine kinases, but not Brachyury, are sufficient to trigger chordoma in zebrafish

The aberrant activation of developmental processes triggers diverse cancer types. Chordoma is a rare, aggressive tumor arising from transformed notochord remnants. Several potentially oncogenic factors have been found to be deregulated in chordoma, yet causation remains uncertain. In particular, sustained expression of TBXT – encoding the notochord regulator protein brachyury – is hypothesized as a key driver of chordoma, yet experimental evidence is absent. Here, we employ a zebrafish chordoma model to identify the notochord-transforming potential of implicated genes in vivo. We find that Brachyury, including a form with augmented transcriptional activity, is insufficient to initiate notochord hyperplasia. In contrast, the chordoma-implicated receptor tyrosine kinases (RTKs) EGFR and Kdr/VEGFR2 are sufficient to transform notochord cells. Aberrant activation of RTK/Ras signaling attenuates processes required for notochord differentiation, including the unfolded protein response and endoplasmic reticulum stress pathways. Our results provide the first in vivo evidence against a tumor-initiating potential of Brachyury in the notochord, and imply activated RTK signaling as a possible initiating event in chordoma. Furthermore, our work points at modulating endoplasmic reticulum and protein stress pathways as possible therapeutic avenues against chordoma.

Summary: An injection-based chordoma model in zebrafish shows that the hypothesized chordoma oncogene brachyury is insufficient, whereas EGFR and VEGFR2 are sufficient, to trigger notochord hyperplasia in our model.

Molecular foundations of primary spinal tumors-implications for surgical management

Primary spinal tumors are rare lesions that require careful clinical management due to their intimate relationship with critical neurovascular structures and the significant associated risk of morbidity. While the advent of molecular and genomic profiling is beginning to impact the management of the cranial counterparts, translation for spinal tumors has lagged behind. Maximal safe surgical resection remains the mainstay of patients with primary spinal tumors, with extent of resection and histology the only consistently identified independent predictors of survival. Adjuvant therapy has had limited impact. To develop targeted neoadjuvant and adjuvant therapies, improve prognostication, and enhance patient selection in spinal oncology, a thorough understanding of the current molecular and genomic landscape of spinal tumors is required. In this review, we detail the epidemiology, current standard-of-care, and molecular features of the most commonly encountered intramedullary spinal cord tumors (IMSCT), intradural extramedullary (IDEM) tumors, and primary spinal column malignancies (PSCM). We further discuss current efforts and future opportunities for integrating molecular advances in spinal oncology with clinical management.

RETRACTED: Inhibition of miR-140-3p or miR-155-5p by antagomir treatment sensitize chordoma cells to chemotherapy drug treatment by increasing PTEN expression

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the authors and the Editor-in-Chief as the validity of the data cannot be guaranteed. The journal was initially contacted by the corresponding author to report that, when the authors verified post publication PTEN as their former target of miR-140-3p, they found that treatment with miR-140-3p or miR-155-5p antagomir increased PTEN protein levels in patient-derived chordoma cells without having a significant effect on the malignancy of the tumor cells. The journal further requested the author to provide more information about their post publication findings with regard to this article. However, the author was not able to fulfil this request.

Molecular Targeted Therapy in the Treatment of Chordoma: A Systematic Review

Objectives: Chordoma is a rare bone malignancy that affects the spine and skull base. Treatment dilemma leads to a high rate of local relapse and distant metastases. Molecular targeted therapy (MTT) is an option for advanced chordoma, but its therapeutic efficacy and safety have not been investigated systematically. Therefore, a systematic review was conducted on studies reporting MTT regimens for chordoma. Methods: Clinical trials, case series and case reports on chordoma MTT were identified using MEDLINE, Cochrane library and EMBASE, and systematically reviewed. Data on clinical outcomes, such as median overall survival, progression-free survival, response rate and adverse events (AEs) were extracted and analyzed. Results: Thirty-three eligible studies were selected for the systematic review, which indicated that imatinib and erlotinib were the most frequently used molecular targeted inhibitors (MTIs) for chordoma. For PDGFR-positive and/or EGFR-positive chordoma, clinical benefits were achieved with acceptable AEs. Monotherapy is preferred as the first-line of treatment, and combined drug therapy as the second-line treatment. In addition, the brachyury vaccine has shown promising results. Conclusions: The selection of MTIs for patients with advanced or relapsed chordoma should be based on gene mutation screening and immunohistochemistry (IHC). Monotherapy of TKIs is recommended as the first-line management, and combination therapy (two TKIs or TKI plus mTOR inhibitor) may be the choice for drug-resistant chordoma. Brachyury vaccine is a promising therapeutic strategy and requires more clinical trials to evaluate its safety and efficacy.

The clinical outcome of recurrent sacral chordoma with further surgical treatment

To analyze the clinical results and related factors of further surgical treatment for recurrent sacral chordomas.Chordomas are rare primary malignant tumors with a high recurrence rate. The treatment of recurrent tumors is difficult and controversial. Contamination by previous operations and disturbed local anatomical structures may increase the risk of reoperation. Most previous studies have focused on the primary tumor; there are very few reports on the clinical diagnosis, treatment, and prognosis of recurrent sacral chordomas.Thirty-four patients with recurrent sacral chordomas from 1979 to 2014 were included in this study. The patients comprised 25 men and 9 women with an average age of 50.7 (24-75) years. The average time until recurrence was 19.4 (4-51) months postoperatively, and 85.3% of the recurrent tumors were located in bone. The patients had an average of 1.2 (1-3) recurrences before further operations were performed in our hospital. The mean maximum tumor diameter was 8.1 (4.6-12.0) cm. Thirty-one patients underwent further tumor resection in our hospital. The postoperative recurrence, metastasis, and survival results were followed and analyzed.The mean follow-up after surgical treatment of recurrence was 49.6 (12-144) months. Nine patients (37.5%) developed recurrence again after an average of 26.7 months. The 3-year and 5-year recurrence-free survival rate was 69.4% and 63.1%, respectively. Multivariate analysis showed that the tumor level within the sacrum (P = .001) and the surgical margin (P = .001) were significant recurrence-related factors. Four patients (16.7%) developed lung metastasis. Eighteen patients were alive at last follow-up. The 5-year and 10-year survival rate after surgical treatment of recurrence was 67.3% and 53.9%, respectively.Most recurrent tumors are located in bone, and a safe osteotomy margin is important. The surgical margin is the only controllable factor of further tumor recurrence. Some patients with recurrence achieve long survival and obtain a clinical benefit from repeated operations if complete resection is achieved.

Imatinib and everolimus in patients with progressing advanced chordoma: A phase 2 clinical study

BACKGROUND

We present the results of an academic phase 2 study on imatinib plus everolimus in patients who have progressive advanced chordoma.

METHODS

In January 2011, 43 adult chordoma patients were enrolled in the study and received imatinib 400 mg/day and everolimus 2.5 mg/day until progression or limiting toxicity. Eligible patients had progressed in the 6 months before study entry. PDGFRB, S6, and 4EBP1 expression and phosphorylation were evaluated by way of immunohistochemistry and/or western blotting. The primary endpoint was the overall response rate (ORR) according to Choi criteria. Secondary endpoints were RECIST 1.1 response, progression-free survival (PFS), overall survival (OS), correlation between S6/4EBP1 phosphorylation and response.

RESULTS

Thirteen of 43 patients were pretreated with imatinib. Among 40 of the 43 patients who were evaluable by Choi criteria, the best responses were 9 with partial response (ORR, 20.9%), 24 with stable disease (SD) (ORR, 55.8%), and 7 with progressive disease (ORR, 16.3%). Forty-two patients were evaluable by RECIST criteria, with 1 partial response (ORR, 2.3%), 37 stable disease (ORR, 86%), and 4 progressive disease (ORR, 9.3%). The median PFS according to Choi criteria was 11.5 months (range, 4.6-17.6 months), and 58.8% and 48.1% of patients were progression-free at 9 and 12 months, respectively. The median PFS by RECIST criteria was 14 months; the median OS was 47.1 months. When assessable, S6/4EBP1 was phosphorylated in a high and moderate/low proportion of tumor cells in responsive and nonresponsive patients, respectively. Toxicity caused a temporary and definitive treatment discontinuation in 60.5% and 30.2% of patients, respectively.

CONCLUSIONS

Imatinib plus everolimus showed a limited activity in progressing advanced chordoma. Interestingly, the amount of tumor cells activated for mammalian target of rapamycin effectors correlated with the response. Toxicity was not negligible.

Role of intraoperative radiotherapy in the treatment of sacral chordoma

BACKGROUND CONTEXT

Sacral chordoma is a rare entity with high local recurrence rates when complete resection is not achieved. To date, there are no series available in literature combining surgery and intraoperative radiotherapy (IORT).

PURPOSE

The objective of this study was to report the experience of our center in the management of sacral chordoma combining radical resection with both external radiotherapy and IORT.

STUDY DESIGN

This is a retrospective case series.

PATIENT SAMPLE

The patient sample included 15 patients with sacral chordoma resected in our center from 1998 to 2015.

OUTCOME MEASURES

The outcome measures were overall survival (OS), disease-free survival (DFS), and rates of local and distant recurrences.

METHODS

We retrospectively reviewed the records of all the patients with sacral chordoma resected in our center from 1998 to December 2015. Overall survival, DFS, and rates of local and distant recurrences were calculated. Results between patients treated with or without IORT were compared.

RESULTS

A total of 15 patients were identified: 8 men and 7 women. The median age was 59 years (range 28-77). Intraoperative radiotherapy was applied in nine patients and six were treated with surgical resection without IORT. In 13 patients, we performed the treatment of the primary tumor, and in two patients, we performed the treatment of recurrence disease. A posterior approach was used in four patients. Wide surgical margins (zero residue) were achieved in six patients, marginal margins (microscopic residue) were achieved in seven patients, and there were no patients with intralesional (R2) margins. At a median follow-up of 38 months (range 11-209 months), the 5-year OS in the IORT group was 100% versus 53% in the group of non-IORT (p=.05). The median DFS in the IORT group was 85 months, and that in the non-IORT group was 41 months. In the group without IORT, two patients died and nobody died during the follow-up in the group treated with IORT. High-sacrectomy treated patients had a median survival of 41 months, and low-sacrectomy treated patients had a median survival of 90 months. Disease-free survival in patients without gluteal involvement was 100% at 5 years, and that in patients with gluteal involvement was 40%. All patients with a recurrence in our study had gluteal involvement.

CONCLUSIONS

Multidisciplinary management of sacral chordoma seems to improve local control. The use of IORT, in our experience, is associated with an increase in OS and DFS. The level of resection and gluteal involvement seems to affect survival. The posterior approach is useful in selected cases. Multicenter studies should be performed to confirm the utility of IORT.

Comprehensive analysis of mRNA-lncRNA co-expression profile revealing crucial role of imprinted gene cluster DLK1-MEG3 in chordoma

Chordoma is a rare bone tumor with high recurrence rate, but the mechanism of its development is unclear. Long non-coding RNAs(lncRNAs) are recently revealed to be regulators in a variety of biological processed by targeting on mRNA transcription. Their expression profile and function in chordoma have not been investigated yet. In this study, we firstly performed the comprehensive analysis of the lncRNA and coding genes expression analysis with three chordoma samples and three fetal nucleus pulposus tissues. lncRNA and gene microarrays were used to determine the differentially expressed lncRNAs and protein coding genes. 2786 lncRNAs and 3286 coding genes were significantly up-regulated in chordoma, while 2042 lncRNAs and 1006 coding genes were down-regulated. Pearson correlation analysis was conducted to correlate differentially expressed lncRNAs with protein coding genes, indicating a comprehensive lncRNA-coding gene co-expression network in chordoma. Cis-correlation analysis showed that various transcripts of MEG3 and MEG8 were paired with the most differentially expressed gene DLK1. As located in the same locus, we further analyzed the miRNA clusters in this region, and identified that 61.22% of these miRNAs were significantly down-regulated, implying the silence of the imprinted gene cluster DLK1-MEG3. Overexpression of MEG3 suppressed the proliferation of chordoma cells. Our study pointed out the potential role of lncRNAs in chordoma, presented the lncRNA-coding genes co-expression profile, and revealed that imprinted gene cluster DLK1-MEG3 contributes to the pathogenesis of chordoma development.

The driver landscape of sporadic chordoma

Chordoma is a malignant, often incurable bone tumour showing notochordal differentiation. Here, we defined the somatic driver landscape of 104 cases of sporadic chordoma. We reveal somatic duplications of the notochordal transcription factor brachyury (T) in up to 27% of cases. These variants recapitulate the rearrangement architecture of the pathogenic germline duplications of T that underlie familial chordoma. In addition, we find potentially clinically actionable PI3K signalling mutations in 16% of cases. Intriguingly, one of the most frequently altered genes, mutated exclusively by inactivating mutation, was LYST (10%), which may represent a novel cancer gene in chordoma.Chordoma is a rare often incurable malignant bone tumour. Here, the authors investigate driver mutations of sporadic chordoma in 104 cases, revealing duplications in notochordal transcription factor brachyury (T), PI3K signalling mutations, and mutations in LYST, a potential novel cancer gene in chordoma.

MicroRNA profiling and bioinformatics analyses reveal the potential roles of microRNAs in chordoma

Chordoma is a rare aggressive bone tumor arising from remnants of the notochord, and patients with chordoma have a poor prognosis. However, the unique expression profiles of microRNAs (miRNAs/miRs) and their downstream signaling pathways in chordoma remain incompletely characterized. The aim of the present study was to delineate the global miRNA expression profile and associated signaling networks in chordoma. miRNA profiling was performed on chordoma and fetal notochord tissues. Differentially expressed miRNAs in chordoma were analyzed using microarrays with hierarchical clustering analysis. The target genes of the differentially expressed miRNAs were predicted, and Gene Ontology (GO) and pathway analyses were performed for the intersecting genes. A total of 42 miRNAs were significantly dysregulated in chordoma compared with that in fetal nucleus pulposus tissues. The expression of hsa-miR-21-3p, hsa-miR-150-5p, hsa-miR-1290 and hsa-miR-623 were validated using the reverse transcription-quantitative polymerase chain reaction. On the basis of the intersection predicted by three databases (Targetscan, microRNA.org and PITA), 10,292 potential miRNA targets were identified. Bioinformatic analyses suggested that these dysregulated miRNAs and their predicted targets were functions of signaling pathways in cancer, the mitogen-activated protein kinase signaling pathway, regulation of actin cytoskeleton, focal adhesion and endocytosis. In particular, human (hsa-)miR-185-5p was identified as a crucial miRNA in chordoma development via the Wnt signaling pathway. The results of the present study provide a comprehensive expression and functional profile of differentially expressed miRNAs associated with chordoma. This profile may serve as a potential tool for biomarker and therapeutic target identification in patients with chordoma.

Establishment and genomic characterization of the new chordoma cell line Chor-IN-1

Chordomas are rare, slowly growing tumors with high medical need, arising in the axial skeleton from notochord remnants. The transcription factor “brachyury” represents a distinctive molecular marker and a key oncogenic driver of chordomas. Tyrosine kinase receptors are also expressed, but so far kinase inhibitors have not shown clear clinical efficacy in chordoma patients. The need for effective therapies is extremely high, but the paucity of established chordoma cell lines has limited preclinical research. Here we describe the isolation of the new Chor-IN-1 cell line from a recurrent sacral chordoma and its characterization as compared to other chordoma cell lines. Chor-IN-1 displays genomic identity to the tumor of origin and has morphological features, growth characteristics and chromosomal abnormalities typical of chordoma, with expression of brachyury and other relevant biomarkers. Chor-IN-1 gene variants, copy number alterations and kinome gene expression were analyzed in comparison to other four chordoma cell lines, generating large scale DNA and mRNA genomic data that can be exploited for the identification of novel pharmacological targets and candidate predictive biomarkers of drug sensitivity in chordoma. The establishment of this new, well characterized chordoma cell line provides a useful tool for the identification of drugs active in chordoma.

A potential therapy for chordoma via antibody-dependent cell-mediated cytotoxicity employing NK or high-affinity NK cells in combination with cetuximab

OBJECTIVE Chordoma is a rare bone tumor derived from the notochord and is resistant to conventional therapies such as chemotherapy, radiotherapy, and targeting therapeutics. Expression of epidermal growth factor receptor (EGFR) in a large proportion of chordoma specimens indicates a potential target for therapeutic intervention. In this study the authors investigated the potential role of the anti-EGFR antibody cetuximab in immunotherapy for chordoma. METHODS Since cetuximab is a monoclonal antibody of the IgG1 isotype, it has the potential to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) employing natural killer (NK) cells as effectors. Polymorphisms in the CD16 allele expressed on NK cells have been shown to influence the degree of ADCC of tumor cells, with the high-affinity valine (V)/V allele being responsible for more lysis than the V/phenylalanine (F) or FF allele. Unfortunately, however, only approximately 10% of the population expresses the VV allele on NK cells. An NK cell line, NK-92, has now been engineered to endogenously express IL-2 and the high-affinity CD16 allele. These irradiated high-affinity (ha)NK cells were analyzed for lysis of chordoma cells with and without cetuximab, and the levels of lysis observed in ADCC were compared with those of NK cells from donors expressing the VV, VF, and FF alleles. RESULTS Here the authors demonstrate for the first time 1) that cetuximab in combination with NK cells can mediate ADCC of chordoma cells; 2) the influence of the NK CD16 polymorphism in cetuximab-mediated ADCC for chordoma cell lysis; 3) that engineered haNK cells-that is, cells transduced to express the CD16 V158 FcγRIIIa receptor-bind cetuximab with similar affinity to normal NK cells expressing the high-affinity VV allele; and 4) that irradiated haNK cells induce ADCC with cetuximab in chordoma cells. CONCLUSIONS These studies provide rationale for the use of cetuximab in combination with irradiated haNK cells for therapy for chordoma.

Brachyury gene copy number gain and activation of the PI3K/Akt pathway: association with upregulation of oncogenic Brachyury expression in skull base chordoma

OBJECTIVE Chordoma is a slow-growing but clinically malignant tumor, and the prognosis remains poor in many cases. There is a strong impetus to develop more effective targeted molecular therapies. On this basis, the authors investigated the potential of Brachyury, a transcription factor involved in notochord development, as a candidate molecular target for the treatment of chordoma. METHODS Brachyury gene copy number and expression levels were evaluated by quantitative polymerase chain reaction in 27 chordoma samples, and the transcriptomes of Brachyury high-expression tumors (n = 4) and Brachyury low-expression tumors (n = 4) were analyzed. A chordoma cell line (U-CH2) was used to investigate the signaling pathways that regulate Brachyury expression. RESULTS All chordoma specimens expressed Brachyury, and expression levels varied widely. Patients with higher Brachyury expression had significantly shorter progression-free survival (5 months, n = 11) than those with lower expression (13 months, n = 16) (p = 0.03). Somatic copy number gain was confirmed in 12 of 27 (44%) cases, and copy number was positively correlated with Brachyury expression (R = 0.61, p < 0.001). Expression of PI3K/Akt pathway genes was upregulated in Brachyury high-expression tumors, and suppression of PI3K signaling led to reduced Brachyury expression and inhibition of cell growth in the U-CH2 chordoma cell line. CONCLUSIONS Activation of the PI3K/Akt pathway and Brachyury copy number gain are strongly associated with Brachyury overexpression, which appears to be a key event in chordoma growth regulation. These findings suggest that targeting Brachyury and PI3K/Akt signaling may be an effective new approach for treating chordoma.

Notochordal Tumors: An Update on Molecular Pathology with Therapeutic Implications

Recent molecular investigations of chordoma show common expression of various receptor tyrosine kinases and activation of downstream signaling pathways contributing to tumor growth and progression. The transcription factor brachyury (also known as T) is important in notochord differentiation, and germline duplication of the gene is often found in familial chordomas. Nuclear expression of brachyury is consistent in chordoma and in benign notochordal cell tumor. Based on the molecular evidence, targeting of several kinds of molecular agents has been attempted for the treatment of uncontrolled chordomas and achieved partial response or stable condition in many cases.

Kinase Activity in Recurring Primary Skull Base Chordomas and Chondrosarcomas: Identification of Novel Pathways of Oncogenesis and Potential Drug Targets

BACKGROUND

Chordomas and chondrosarcomas can occur in the skull base. Currently, 45% of chordomas and 56% of chondrosarcomas recur within 5 years of surgery. The role of adjuvant therapy is highly debated. No pharmacotherapies have been approved by the U.S. Food and Drug Administration for chordomas or chondrosarcomas. High propensity for recurrence and lack of definitive adjuvant therapy necessitate additional basic science research to identify molecular anomalies associated with recurrent disease.

METHODS

We pooled tumor lysates from patients based on clinical criteria into 4 groups: primary chordomas, primary chordomas that recurred, primary chondrosarcomas, and primary chondrosarcomas that recurred. We used a peptide labeling method, isobaric tags for relative and absolute quantitation, to uniquely identify each tumor group. Phosphorylated peptides were identified and quantified via mass spectroscopy to determine and predict active kinases.

RESULTS

Six groups of phosphorylated peptides were associated with primary tumors that later recurred. Specific kinases associated with primary chordomas that recurred were FES and FER. Specific kinases associated with primary chondrosarcomas that recurred were FES, FER, SRC family kinases, PKC, ROCK, and mitogen-activated protein kinase signaling (JNK, ERK1, p38).

CONCLUSIONS

These data provide clinicians with a means to screen skull base chordomas and chondrosarcomas to help identify tumors with a propensity to recur. Many of these kinases can be efficaciously inhibited by Food and Drug Administration-approved drugs that have not yet been used in clinical trials for treatment of skull base chordomas or chondrosarcomas. Validation of kinases identified in this study may advance treatment options for patients with these tumors.

Genetic aberrations and molecular biology of skull base chordoma and chondrosarcoma

Chordomas and chondrosarcomas are two major malignant bone neoplasms located at the skull base. These tumors are rarely metastatic, but can be locally invasive and resistant to conventional chemotherapies and radiotherapies. Accordingly, therapeutic approaches for the treatment of these tumors can be difficult. Additionally, their location at the skull base makes them problematic. Although accurate diagnosis of these tumors is important because of their distinct prognoses, distinguishing between these tumor types is difficult due to overlapping radiological and histopathological findings. However, recent accumulation of molecular and genetic studies, including extracranial location analysis, has provided us clues for accurate diagnosis. In this report, we review the genetic aberrations and molecular biology of these two tumor types. Among the abundant genetic features of these tumors, brachyury immunohistochemistry and direct sequencing of IDH1/2 are simple and useful techniques that can be used to distinguish between these tumors. Although it is still unclear why these tumors, which have such distinct genetic backgrounds, show similar histopathological findings, comparison of their genetic backgrounds could provide essential information.

Spinal stereotactic body radiotherapy following intralesional curettage with separation surgery for initial or salvage chordoma treatment

OBJECTIVE Chordoma is a rare malignant tumor for which en bloc resection with wide margins is advocated as primary treatment. Unfortunately, due to anatomical constraints, en bloc resection to achieve wide or marginal margins is not feasible for many patients as the resulting morbidity would be prohibitive. The objective of this study was to evaluate the efficacy of intralesional curettage and separation surgery followed by spinal stereotactic body radiation therapy (SBRT) in patients with chordomas in the mobile spine. METHODS The authors performed a retrospective chart review of all patients with chordoma in the mobile spine treated from 2004 to 2016. Patients were identified from a prospectively collected database. Initially 22 patients were identified with mobile spine chordomas. With inclusion criteria of cytoreductive separation surgery followed closely by SBRT and a minimum of 6 months of follow-up imaging, 12 patients were included. Clinical and pathological characteristics of each patient were collected and data were analyzed. Patients were divided into two cohorts-those undergoing intralesional resection followed by SBRT as initial chordoma treatment at Memorial Sloan Kettering Cancer Center (MSKCC) (Cohort 1) and those undergoing salvage treatment following recurrence (Cohort 2). Treatment toxicities were classified according to the Common Terminology Criteria for Adverse Events version 4.03. Overall survival was analyzed using Kaplan-Meier analysis. RESULTS The 12 patients had a median post-SBRT follow-up time of 26 months. Cohort 1 had 5 patients with median post-SBRT follow-up time of 65.9 months and local control rate of 80% at last follow-up. Only one patient had disease progression, at 48.2 months following surgery and SBRT. Cohort 2 had 7 patients who had been treated at other institutions prior to undergoing both surgery and SBRT (salvage therapy) at MSKCC. The local control rate was 57.1% and the median follow-up duration was 10.7 months. One patient required repeat irradiation. Major surgery- and radiation-related complications occurred in 18% and 27% of patients, respectively. Epidural spinal cord compression scores were collected for each patient pre- and postoperatively. CONCLUSIONS The combination of surgery and SBRT provides excellent local control following intralesional curettage and separation surgery for chordomas in the mobile spine. Patients who underwent intralesional curettage and spinal SBRT as initial treatment had better disease control than those undergoing salvage therapy. High-dose radiotherapy may offer several biological benefits for tumor control.

Metastatic Chordoma of the Tongue: Case Report

Chordomas are rare bone tumors that arise from notochord remnants. They most commonly occur in the sacrum, but they also can be seen in the skull base, cervical spine, and thoracolumbar vertebrae. Chordomas account for 1 to 4% of all primary skeletal tumors. They are usually indolent, locally growing tumors. Distant metastasis has been reported in 3 to 48% of cases. When metastasis occurs, it is usually observed in the lung, bone, and liver. To the best of our knowledge, no case of a chordoma metastasis to the tongue has been previously reported in the literature. We report such a case in a 61-year-old man.

Establishment and characterization of a chordoma cell line from the tissue of a patient with dedifferentiated-type chordoma

OBJECTIVE

Chordoma is a rare bone tumor of the axial skeleton believed to originate from the remnants of the embryonic notochord. The available tumor cells are characteristically physaliferous and express brachyury, a transcription factor critical for mesoderm specification. Although chordomas are histologically not malignant, treatments remain challenging because they are resistant to radiation therapy and because wide resection is impossible in most cases. Therefore, a better understanding of the biology of chordomas using established cell lines may lead to the advancement of effective treatment strategies. The authors undertook a study to obtain this insight.

METHODS

Chordoma cells were isolated from the tissue of a patient with dedifferentiated-type chordoma (DTC) that had recurred. Cells were cultured with DMEM/F12 containing 10% fetal bovine serum and antibiotics (penicillin and streptomycin). Cell proliferation rate was measured by MTS assay. Cell-cycle distribution and cell surface expression of proteins were analyzed by fluorescence-activated cell sorting (FACS) analysis. Expression of proteins was analyzed by Western blot and immunocytochemistry. Radiation resistance was measured by clonogenic survival assay. Tumor formation was examined by injection of chordoma cells at hindlimb of nude mice.

RESULTS

The putative (DTC) cells were polygonal and did not have the conventional physaliferous characteristic seen in the U-CH1 cell line. The DTC cells exhibited similar growth rate and cell-cycle distribution, but they exhibited higher clonogenic activity in soft agar than U-CH1 cells. The DTC cells expressed high levels of platelet-derived growth factor receptor–β and a low level of brachyury and cytokeratins; they showed higher expression of stemness-related and epithelial to mesenchymal transition–related proteins than the U-CH1 cells. Intriguingly, FACS analysis revealed that DTC cells exhibited marginal surface expression of CD24 and CD44 and high surface expression of CXCR4 in comparison to U-CH1 cells. In addition, blockade of CXCR4 with its antagonist AMD3100 effectively suppressed the growth of both cell lines. The DTC cells were more resistant to paclitaxel, cisplatin, etoposide, and ionizing radiation than the U-CH1 cells. Injection of DTC cells into the hindlimb region of nude mice resulted in the efficient formation of tumors, and the histology of xenograft tumors was very similar to that of the original patient tumor.

CONCLUSIONS

The use of the established DTC cells along with preestablished cell lines of chordoma may help bring about greater understanding of the mechanisms underlying the chordoma that will lead to therapeutic strategies targeting chordomas.

EGFR inhibitors identified as a potential treatment for chordoma in a focused compound screen

Chordoma is a rare malignant bone tumour with a poor prognosis and limited therapeutic options. We undertook a focused compound screen (FCS) against 1097 compounds on three well-characterized chordoma cell lines; 154 compounds were selected from the single concentration screen (1 µm), based on their growth-inhibitory effect. Their half-maximal effective concentration (EC50 ) values were determined in chordoma cells and normal fibroblasts. Twenty-seven of these compounds displayed chordoma selective cell kill and 21/27 (78%) were found to be EGFR/ERBB family inhibitors. EGFR inhibitors in clinical development were then studied on an extended cell line panel of seven chordoma cell lines, four of which were sensitive to EGFR inhibition. Sapitinib (AstraZeneca) emerged as the lead compound, followed by gefitinib (AstraZeneca) and erlotinib (Roche/Genentech). The compounds were shown to induce apoptosis in the sensitive cell lines and suppressed phospho-EGFR and its downstream pathways in a dose-dependent manner. Analysis of substituent patterns suggested that EGFR-inhibitors with small aniline substituents in the 4-position of the quinazoline ring were more effective than inhibitors with large substituents in that position. Sapitinib showed significantly reduced tumour growth in two xenograft mouse models (U-CH1 xenograft and a patient-derived xenograft, SF8894). One of the resistant cell lines (U-CH2) was shown to express high levels of phospho-MET, a known bypass signalling pathway to EGFR. Neither amplifications (EGFR, ERBB2, MET) nor mutations in EGFR, ERBB2, ERBB4, PIK3CA, BRAF, NRAS, KRAS, PTEN, MET or other cancer gene hotspots were detected in the cell lines. Our findings are consistent with the reported (p-)EGFR expression in the majority of clinical samples, and provide evidence for exploring the efficacy of EGFR inhibitors in the treatment of patients with chordoma and studying possible resistance mechanisms to these compounds in vitro and in vivo. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Durable Response of Spinal Chordoma to Combined Inhibition of IGF-1R and EGFR

Chordomas are rare primary malignant bone tumors arising from embryonal notochord remnants of the axial skeleton. Chordomas commonly recur following surgery and radiotherapy, and there is no effective systemic therapy. Previous studies implicated receptor tyrosine kinases, including epidermal growth factor receptor (EGFR) and type 1 insulin-like growth factor receptor (IGF-1R), in chordoma biology. We report an adult female patient who presented in 2003 with spinal chordoma, treated with surgery and radiotherapy. She underwent further surgery for recurrent chordoma in 2008, with subsequent progression in pelvic deposits. In June 2009, she was recruited onto the Phase I OSI-906-103 trial of EGFR inhibitor erlotinib with linsitinib, a novel inhibitor of IGF-1R/insulin receptor (INSR). Treatment with 100 mg QD erlotinib and 50 mg QD linsitinib was well-tolerated, and after 18 months a partial response was achieved by RECIST criteria. From 43 months, a protocol modification allowed intra-patient linsitinib dose escalation to 50 mg BID. The patient remained stable on trial treatment for a total of 5 years, discontinuing treatment in August 2014. She subsequently experienced further disease progression for which she underwent pelvic surgery in April 2015. Analysis of DNA extracted from 2008 (pre-trial) tissue showed that the tumor harbored wild-type EGFR, and a PIK3CA mutation was detected in plasma, but not tumor DNA. The 2015 (post-trial) tumor harbored a mutation of uncertain significance in ATM, with no detectable mutations in other components of a 50 gene panel, including EGFR, PIK3CA, and TP53. By immunohistochemistry, the tumor was positive for brachyury, the molecular hallmark of chordoma, and showed weak–moderate membrane and cytoplasmic EGFR. IGF-1R was detected in the plasma membrane and cytoplasm and was expressed more strongly in recurrent tumor than the primary. We also noted heterogeneous nuclear IGF-1R, which has been linked with sensitivity to IGF-1R inhibition. Similar variation in IGF-1R expression and subcellular localization was noted in 15 further cases of chordoma. In summary, this exceptionally durable response suggests that there may be merit in evaluating combined IGF-1R/INSR and EGFR inhibition in patients with chordomas that recur following failure of local treatment.

Chordoma: an update on the pathophysiology and molecular mechanisms

Chordoma is a rare low-grade primary malignant skeletal tumor, which is presumed to derive from notochord remnants. The pathogenesis of chordoma has not been fully elucidated. However, recent advances in the molecular biology studies have identified brachyury underlying the initiation and progression of chordoma cells. More efforts have been made on accumulating evidence of the notochordal origin of chordoma, discovering signaling pathways and identifying crucial targets in chordomagenesis. In this review, we summarize the most recent research findings and focus on the pathophysiology and molecular mechanisms of chordoma.

Histology-Driven Therapy

Soft tissue tumors (STTs) are rare mesenchymal neoplasms accounting for less than 1% of adult cancers. More than 50 different subtypes of STTs have been identified, with this number expected to grow as our understanding of the complex genetic landscape of these diseases improves. As the classification of soft tissue neoplasms continues to diversify, so does the approach to therapy. Accurate histopathologic diagnosis, utilizing the appropriate ancillary immunohistochemical and molecular diagnostic platforms, underpins the oncologic management of soft tissue sarcomas. As increasing numbers of reproducible genetic abnormalities in soft tissue neoplasms are defined, molecular genetic and molecular cytogenetic investigations have become a standard part of the ancillary diagnostic repertoire. However, other soft tissue neoplasms lack reproducible genetic abnormalities, and for these, traditional histology and immunohistochemistry remain the cornerstones for diagnosis. Here, we give an overview of histology-driven therapy in STTs, highlighting the critical role of accurate surgical pathology in guiding the systemic treatment of patients with these neoplasms, and the importance of close collaboration between the surgical pathologist and the oncologist. We also summarize what is considered standard practice in nonhistology- and histology-driven therapy.

Novel targeted therapies in chordoma: an update

Chordomas are rare, locally aggressive skull base neoplasms known for local recurrence and not-infrequent treatment failure. Current evidence supports the role of maximal safe surgical resection. In addition to open skull-base approaches, the endoscopic endonasal approach to clival chordomas has been reported with favorable albeit early results. Adjuvant radiation is prescribed following complete resection, alternatively for gross residual disease or at the time of recurrence. The modalities of adjuvant radiation therapy reported vary widely and include proton-beam, carbon-ion, fractionated photon radiotherapy, and photon and gamma-knife radiosurgery. As of now, no direct comparison is available, and high-level evidence demonstrating superiority of one modality over another is lacking. While systemic therapies have yet to form part of any first-line therapy for chordomas, a number of targeted agents have been evaluated to date that inhibit specific molecules and their respective pathways known to be implicated in chordomas. These include EGFR (erlotinib, gefitinib, lapatinib), PDGFR (imatinib), mTOR (rapamycin), and VEGF (bevacizumab). This article provides an update of the current multimodality treatment of cranial base chordomas, with an emphasis on how current understanding of molecular pathogenesis provides a framework for the development of novel targeted approaches.

PD-1, PD-L1, PD-L2 expression in the chordoma microenvironment

Chordomas are rare malignant tumors that are postulated to arise from remnants of the notochord. Currently, the interaction between chordomas and the host immune system is poorly understood. The checkpoint protein, PD-1 is expressed by circulating lymphocytes and is a marker of activation and exhaustion. Its ligands, PD-L1 (B7-H1, CD274) and PD-L2 (B7-DC, CD273), are expressed on a variety of human cancers; however this pathway has not been previously reported in chordomas. We used flow cytometric and RT-PCR analysis in three established primary and recurrent chordoma cell lines (U-CH1, U-CH2, and JHC7) as well as immunohistochemical analysis of chordoma tissues from 10 patients to identify and localize expression of PD-1 pathway proteins. PD-1 ligands are not constitutively expressed by chordoma cells, but their expression is induced in the setting of pro-inflammatory cytokines in all cell lines examined. In paraffin embedded tissues, we found that tumor infiltrating lymphocytes expressed PD-1 in 3/6 cases. We also found that, although chordoma cells did not express significant levels of PD-L1, PD-L1 expression was observed on tumor-infiltrating macrophages and tumor infiltrating lymphocytes. Our study suggests that PD-1, PD-L1, and PD-L2 are present in the microenvironment of a subset of chordomas analyzed. Future studies are needed to evaluate the contribution of the PD-1 pathway to the immunosuppressive microenvironment of chordomas.

ErbB receptors as prognostic and therapeutic drug targets in bone and soft tissue sarcomas

ErbB receptors have been intensely studied to understand their importance in cancer biology and as therapeutic targets, and many ErbB inhibitors are now used in the clinical setting. A large number of studies have been conducted to examine the expression of ErbB family members in bone and soft tissue sarcomas, including osteosarcomas, synovial sarcomas, Ewing sarcomas, rhabdomyosarcomas, and so on. Nevertheless, the clinical implications of ErbB receptors remain elusive. To illustrate the potential of ErbB family members as prognostic and therapeutic drug targets in bone and soft tissue sarcomas, we summarized the molecular evidence and observations from clinical and basic trials.

Chordoma: the entity

Chordomas are malignant tumors of the axial skeleton, characterized by their locally invasive and slow but aggressive growth. These neoplasms are presumed to be derived from notochordal remnants with a molecular alteration preceding their malignant transformation. As these tumors are most frequently observed on the skull base and sacrum, patients suffering from a chordoma present with debilitating neurological disease, and have an overall 5-year survival rate of 65%. Surgical resection with adjuvant radiotherapy is the first-choice treatment modality in these patients, since chordomas are resistant to conventional chemotherapy. Even so, management of chordomas can be challenging, as chordoma patients often present with recurrent disease. Recent advances in the understanding of the molecular events that contribute to the development of chordomas are promising; the most novel finding being the identification of brachyury in the disease process. Here we present an overview of the current paradigms and summarize relevant research findings.