The NIH pediatric/young adult chordoma clinic and natural history study: Making advances in a very rare tumor

BACKGROUND

Chordomas are rare tumors arising from the skull base and spine, with approximately 20 pediatric chordoma cases in the Unitedn States per year. The natural history and optimal treatment of pediatric chordomas, especially poorly differentiated and dedifferentiated subtypes, is incompletely understood. Herein, we present findings from our first National Cancer Institute (NCI) chordoma clinic and a retrospective analysis of published cases of pediatric poorly differentiated chordomas (PDC) and dedifferentiated chordomas (DC).

METHODS

Patients less than 40 years old with chordoma were enrolled on the NCI Natural History and Biospecimens Acquisitions Study for Children and Adults with Rare Solid Tumors protocol (NCT03739827). Chordoma experts reviewed patient records, evaluated patients, and provided treatment recommendations. Patient-reported outcomes, biospecimens, and volumetric tumor analyses were collected. A literature review for pediatric PDC and DC was conducted.

RESULTS

Twelve patients (median age: 14 years) attended the clinic, including four patients with active disease and three patients with PDC responsive to systemic therapy. Consensus treatment, management, and recommendations were provided to patients. Literature review returned 45 pediatric cases of PDC or DC with variable treatments and outcomes.

CONCLUSIONS

A multidisciplinary expert clinic was feasible and successful in improving understanding of pediatric chordoma. While multimodal approaches have all been employed, treatment for PDC has been inconsistent and a recommended standardized treatment approach has not been defined. Centralized efforts, inclusive of specialized chordoma-focused clinics, natural history studies, and prospective analyses will help in the standardization of care for this challenging disease.

Activity of pemetrexed in pre-clinical chordoma models and humans

Chordomas are rare slow growing tumors, arising from embryonic remnants of notochord with a close predilection for the axial skeleton. Recurrence is common and no effective standard medical therapy exists. Thymidylate synthase (TS), an intracellular enzyme, is a key rate-limiting enzyme of DNA biosynthesis and repair which is primarily active in proliferating and metabolically active cells. Eighty-four percent of chordoma samples had loss of TS expression which may predict response to anti-folates. Pemetrexed suppresses tumor growth by inhibiting enzymes involved in folate metabolism, resulting in decreased availability of thymidine which is necessary for DNA synthesis. Pemetrexed inhibited growth in a preclinical mouse xenograft model of human chordoma. We report three cases of metastatic chordoma that had been heavily treated previously with a variety of standard therapies with poor response. In two cases, pemetrexed was added and objective responses were observed on imaging with one patient on continuous treatment for > 2 years with continued shrinkage. One case demonstrated tumor growth after treatment with pemetrexed. The two cases which had a favorable response had a loss of TS expression, whereas the one case with progressive disease had TS present. These results demonstrate the activity of pemetrexed in recurrent chordoma and warrant a prospective clinical trial which is ongoing (NCT03955042).

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.

Abstract 4865: Mechanisms of EGFR inhibitor sensitivity and resistance in chordoma

Target discovery studies have identified EGFR inhibition as a promising therapeutic strategy in chordoma, motivating ongoing clinical trials. Yet EGFR is not mutated in chordoma, leaving the mechanisms associated with EGFR inhibitor (EGFRi) sensitivity and resistance unclear. In this study, we profiled a panel of over 10 chordoma cell lines to categorize their sensitivity to afatinib, a second-generation EGFRi with potency against the wild-type receptor. Several cell lines, including U-CHCF365, UM-Chor1, MUG-Chor1, and U-CH1, were highly sensitive to afatinib in cell viability assays, with absolute IC50 values below 50 nanomolar. In contrast, other chordoma cell lines, including UM-Chor5C and U-CHCF359B, exhibited limited response to EGFRi at concentrations exceeding 1 micromolar. Among sensitive cell lines, we found that afatinib promoted cell death in some cases (e.g., U-CH1) whereas in others it induced a profound cell cycle arrest. Moreover, in U-CH1 cells, acute afatinib treatment enriched a population of drug-tolerant persister cells with a fusiform morphology, potentially indicative of an epithelial-mesenchymal transition. Ongoing studies are focused on understanding the mechanisms of afatinib-induced cell death, drug tolerance, and acquired resistance, with a view to designing rational combination strategies capable of enhancing the magnitude and duration of therapeutic response. In cell lines with matched xenograft models, in vitro responses to afatinib were consistent in vivo. In a panel of 12 chordoma patient-derived xenograft (PDX) models treated with afatinib or cetuximab, differential sensitivity to EGFRi was recapitulated - with EGFRi promoting complete or negligent tumor growth inhibition in sensitive or resistant models, respectively. Finally, we combined drug sensitivity profiling of chordoma cell lines and PDXs with whole-exome and whole-transcriptome sequencing to identify genomic and transcriptomic features associated with sensitivity and resistance to EGFRi in chordoma. Collectively, our data identify a striking degree of differential sensitivity to EGFRi in chordoma, and begin to shed light on factors associated with primary and acquired resistance. These results provide a framework for guiding patient selection and identifying potential combination therapy regimens to improve EGFRi efficacy and address resistance.

Citation Format: Nindo Punturi, Lee Dolat, Joan Levy, Josh Sommer, Daniel M. Freed. Mechanisms of EGFR inhibitor sensitivity and resistance in chordoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4865.

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.

The novel ageing-induced long non-coding RNA MIRIAL controls endothelial cell and mitochondrial function

 

Vascular ageing is a key risk factor for cardiovascular diseases and is characterised by a continuous decline in endothelial cell function. Despite progress in recent years, the molecular mechanisms for this deterioration remain incompletely understood. Long non-coding RNAs (lncRNAs) are a heterogeneous class of RNAs that have been shown to regulate gene expression and protein function, however, little is known about their role in the ageing-associated dysregulation of endothelial cell (EC) function. In this study, we aimed to identify and functionally characterise a novel ageing-regulated lncRNA in ECs.

Using RNA sequencing data of cardiac ECs derived from 12 weeks young and 20 months old mice, we identified Mirial as an ageing-induced lncRNA (1.32-fold, p=0.00005). Mirial is conserved between mice and humans and has no obvious coding potential. GapmeR-mediated silencing of MIRIAL in human umbilical vein ECs (HUVECs) decreased cell proliferation by 50%, migration by 24% (p=0.045) and basal angiogenic sprouting by 53% (p=0.0029), without affecting apoptosis or senescence. Additionally, silencing of MIRIAL increases mitochondrial mass (1.8-fold, p<0.01) and spare respiratory capacity (1.95-fold). Preliminary data from the hearts of Mirial knockout mice confirm the elevated mitochondrial mass after Mirial ablation (1.26-fold, p=0.05). In HUVECS, MIRIAL is mainly associated with the chromatin (80%), suggesting a role in the regulation of gene expression. Pathway analysis showed an overrepresentation of p53 target genes that were upregulated upon MIRIAL knockdown, which was validated using qRT-PCR (1.8–5.2-fold increases). Interestingly, this effect is fully dependent on the presence of p53. Moreover, p53 and phospho-p53 (Ser15) were both increased (1.8-fold, p=0.01 and 2.9-fold, p=0.02, respectively) after MIRIAL silencing. Pulldown of MIRIAL identified DDX5 and MRPL41 as direct p53 interactors and RNA immunoprecipitation revealed that MIRIAL physically interacts with p53 (3.75-fold enrichment, p<0.01). Gene set enrichment analysis of RNA sequencing data revealed that 10% of deregulated genes after MIRIAL knockdown have a binding site for Forkhead Box O (FoxO) transcription factors. In particular, FoxO1 is known as one of the key players in endothelial proliferation and regulation of angiogenesis as well as in mitochondrial biogenesis.

Taken together, MIRIAL is an ageing-induced lncRNA in endothelial cells acting as a key regulator of metabolic and cellular function. MIRIAL promotes cell proliferation, migration and basal angiogenic sprouting while decreasing mitochondrial function. We hypothesise that MIRIAL influences these cellular functions by affecting the p53 pathway and mitochondrial respiration through FoxO signalling. The results from the present study suggest that modulation of cellular MIRIAL expression may be a promising strategy to prevent or even reverse ageing-induced functional decline of ECs, both in vitro and in vivo.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft - Collaborative Research Centre (SFB) 834 - Project B9Deutsche Forschungsgemeinschaft - Collaborative Research Centre/Transregio (TRR) 267 - Project B4

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.

Abstract LB196: SPR965, a PI3K/mTORC1/C2 inhibitor for treatment of chordoma

Introduction: Chordoma is a rare tumor with a median survival of 7 years in US. At present, standard treatment involves surgery and/or radiation. Complete surgical resection, however, can be challenging as the tumor is located on the skull base or spine. Moreover, there is currently no approved systemic therapy for advanced chordoma. These challenges have resulted in significant morbidity and a dismal cure rate of approximately 30%, highlighting the need for development of new therapeutic strategies for this orphan disease. Emerging evidence suggests a key role for the PI3K/mTOR pathway in chordoma and numerous reports point to an enrichment of chordoma cases in individuals with tuberous sclerosis syndrome, which is driven by dysregulated mTOR activity. Another study of chordoma tumors from 111 patients demonstrated that the mTOR pathway was activated in 46% of the tumors, and sequencing studies have revealed oncogenic alterations to the PI3K/mTOR pathway in approximately 15-20% of chordomas. We surmised that dual inhibition of both the mTOR and the PI3K pathways may represent a desirable profile as it will not only have the potential to address the effects of activation of both these targets, but also prevent feedback reactivation of the pathway resulting from the inhibition of one or the other. Previously, SPR965 was shown as a potent, selective and orally bioavailable PI3K and mTOR C1/C2 inhibitor with an excellent PK/ADME profile.

Methods: SPR965 and comparator compounds were evaluated in vitro in the chordoma cell lines JHC7, U-CH1, and U-CH2 by (Resarufin assay). SPR965 was evaluated in vivo in multiple chordoma PDX models.

Results: SPR965 in vitro showed significant effect on cell proliferation with EC50 of 50-90nM. SPR965 was more active at 1uM than PI3K/mTOR inhibitors VS-5584, Bimiralisib, PF-04691502, WYE-687, Dactolisib, and Voxtalisib in the Kinase Chemogenomic Set. SPR965 in vivo monotherapy in SF8894 PDX at 3mg/kg had similar tumor growth inhibition (TGI) to CDK4/6 inhibitor Palbociclib at 50mg/kg. SPR965 combination with Palbocicilib had similar TGI to PI3K inhibitor Buparlisib at 35mg/kg. In CF459 PDX, SPR965 potently inhibited tumor growth at 10mg/kg. TGI% was statistically significant with SPR965 versus untreated controls in both models.

Conclusion: In SF8894 PDX model SPR965 was more efficacious as it produced similar tumor growth inhibition at 12- and 17-fold lower dose than Buparlisib (PI3K) and Palbociclib (CDK4/6) respectively, both these compounds are in phase 2 clinical trials. In CF459 PDX model SPR965 exhibited dose-dependent tumor growth inhibition, and at 10mg/kg profoundly slowed tumor growth compared to Palbociclib. Studies are underway to elucidate potential mechanisms of SPR965 sensitivity. SPR965 represents a significant opportunity for development of a targeted therapeutic for chordoma patients.

Citation Format: Sundeep Dugar, Somdutta Sen, Paul Maffuid, Dan Freed, Josh Sommer, Edward Anderson, Anthony Hickey. SPR965, a PI3K/mTORC1/C2 inhibitor for treatment of chordoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB196.

Abstract 6355: A characterisation of direct and indirect transcription factor inhibition to target brachyury in chordoma

Dysregulated gene programs are a hallmark of cancer, and oncogenic transcription factors (TFs) have emerged as key players that contribute to this cell state. Chordoma is a rare cancer derived from deregulation of the TF brachyury (encoded by the T gene). While brachyury is normally turned off in development and is minimally expressed in healthy tissues, it remains highly expressed and is required in chordoma. TFs like brachyury have been challenging to drug directly, and chordoma represents an ideal system for studying both the biology behind a transcriptional dependency in cancer and how it can therapeutically targeted. Given that chordomas lack targeted therapies, we aim to understand the role of brachyury in the disease, identify therapeutic strategies to target its genetic regulation, and ultimately translate these findings towards the clinic. To achieve this, we sought to compare the consequences of direct and indirect brachyury targeting via targeted protein degradation and transcriptional CDK inhibition. In the absence of a brachyury small molecule, we generated human chordoma cell lines that express only a degradable form of brachyury. With these cell lines, we have mapped the brachyury regulome and have used high resolution microscopy to visualise brachyury genetic regulation. We find that brachyury is an ultra-selective regulator in chordoma, and that brachyury autoregulates through a transcriptional condensate. Both targeted brachyury degradation and transcriptional inhibition with THZ1, a preclinical tool compound inhibiting CDKs 7/12/13, can selectively inhibit T transcription and disrupt the brachyury transcriptional condensate. While these direct and indirect approaches converge to target brachyury, they have distinct phenotypic outcomes; brachyury degradation induces senescence and transcriptional inhibition causes apoptosis. Specifically, brachyury degradation primes cells to treatment with senolytics, which selectively kill senescent chordoma cells. Targeting senescence represents a novel therapeutic strategy in chordoma. Our findings affirm that brachyury is the most promising target in chordoma. We show that while transcriptional inhibition can selectively target brachyury, it mechanistically it contrasts with direct brachyury inhibition. However, these dual therapeutic strategies show that is indeed possible to progress in targeting oncoproteins that have long been considered “undruggable”, and our efforts not only benefit chordoma patients but provide a framework for drugging other transcriptionally addicted cancers.

Citation Format: Hadley E. Sheppard, Alessandra Dall’Agnese, Woojun D. Park, M. Shamim Shamim, Julien Dubrulle, Hannah L. Johnson, Fabio Stossi, Josh Sommer, Joan Levy, Tanaz Sharifnia, Mathias Wawer, Behnam Nabet, Paul A. Clemons, Stuart L. Schreiber, Paul Clarke, Rick Young, Charles Y. Lin, Paul Workman. A characterisation of direct and indirect transcription factor inhibition to target brachyury in chordoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6355.

Catering situation at Austrian schools

Background

Due to the increase in all-day compulsory schools in Austria, it is important that students receive health-promoting meals throughout the day. The aim of the analysis was a nationwide evaluation of the current situation concerning catering at schools.

Methods

Using a nationwide representative sample of schools from the 5th grade upwards, a questionnaire was conducted as a telephone interview with 331 randomly chosen schools. In addition, 56 schools in Vienna from the 5th grade onwards were randomly selected in order to analyze the current offer at school cafeterias in detail.

Results

Lunch was offered at 72% of all schools, a school cafeteria was available at 81%, a cold drink vending machine at 66%, a hot drink vending machine at 41% and a snack vending machine at 23%. With regard to the health promoting composition of the catering offer, 18% of all schools already had a certified lunch menu, 22% a certified school cafeteria, 14% a certified cold drink vending machine and 5% a certified snack vending machine. In 79% of schools there is direct competition for school catering (93% supermarkets, 45% bakeries, 33% snack stands, 8% fast food restaurants). The results of the detailed analysis in Vienna showed that only 35% of all school cafeterias are certified. All of these locations are advised externally.

Conclusions

The majority of the schools offer catering during breaks and at lunchtime. Without external advice, the majority of the offers must be classified as not health promoting.

Key messages

The food offered at schools is an important component in the nutrition of students in Austria. Cafeteria operators in schools often need external advice in order to be able to offer a healthy selection of food and beverages.

The novel ageing-induced long non-coding RNA MIRIAL controls endothelial cell and mitochondrial function

 

Vascular ageing is a key risk factor for cardiovascular diseases and is characterised by a continuous decline in endothelial function. Despite progress in recent years, the molecular mechanisms for this deterioration remain incompletely understood. Long non-coding RNAs (lncRNAs) are a heterogeneous class of RNAs that have been shown to regulate gene expression and protein function, however, little is known about their role in the ageing-associated dysregulation of endothelial cell (EC) function.

In this study, we aimed to identify and functionally characterise a novel ageing-regulated lncRNA in ECs.

Using RNA sequencing data of cardiac ECs from 12 weeks young and 20 months old mice, we identified Mirial as an ageing-induced lncRNA (1.32-fold, p=0.ehab724.33565). MIRIAL is conserved between mice and humans and has no obvious coding potential. GapmeR-mediated silencing of MIRIAL in human umbilical vein ECs (HUVECs) decreased cell proliferation by 50%, migration by 24% (p=0.045) and basal angiogenic sprouting by 53% (p=0.0029), while increasing VEGF-A-stimulated sprouting by 50% (p=0.0139) and not affecting apoptosis or senescence. Subcellular fractionation of HUVECs revealed that MIRIAL was predominantly associated with the chromatin (80%). Pathway analysis of RNA sequencing data showed an overrepresentation of upregulated p53 target genes upon MIRIAL knockdown in HUVECs which was validated using qRT-PCR (1.8–5.2-fold increased). Using siRNA against p53 we showed that this effect is fully dependent on the presence of p53. Moreover, p53 and its phosphorylated form (Ser15) were both increased (1.8-fold, p=0.01 and 2.9-fold, p=0.02) after MIRIAL silencing. Intriguingly, RNA immunoprecipitation revealed that MIRIAL physically interacts with p53 (3.75-fold enriched, p=0.0067). To further study the interactome of MIRIAL, we performed RNA pulldown assays followed by mass spectrometry analysis of bound proteins, which identified the ageing-associated prohibitin (PHB) 1 and 2 to potentially interact with MIRIAL. Similar to MIRIAL knockdown, siRNA-mediated PHB 1 or 2 silencing caused proliferative defects. Further, PHBs are known to physically interact with p53 and control mitochondrial metabolism, a key factor in cellular ageing. Interestingly, silencing of MIRIAL in HUVECs increased mitochondrial mass (1.8-fold, p=0.0008) and spare respiratory capacity (1.95-fold) with the latter being decreased in isolated aged murine ECs.

Taken together, MIRIAL is an ageing-induced lncRNA in ECs acting as a key regulator of metabolic and cellular function. MIRIAL promotes cell proliferation, migration and basal angiogenic sprouting while decreasing mitochondrial function and VEGF-A-stimulated sprouting. We hypothesise that MIRIAL influences p53 signalling and mitochondrial respiration through PHB 1 and 2. The present study suggests that modulation of MIRIAL expression may be a promising strategy to prevent or even reverse ageing-induced functional decline of ECs.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Research Council (ERC) Starting Grant: Non-coding RNA in Vascular Ageing (NOVA)

Abstract LB216: Targeted brachyury degradation disrupts a highly specific autoregulatory program controlling chordoma cell identity

Chordomas are rare spinal tumors addicted to expression of the developmental transcription factor brachyury. In chordomas, brachyury is super-enhancer associated and preferentially downregulated by pharmacologic transcriptional CDK inhibition leading to cell death. To understand the underlying basis of this sensitivity, we dissect the brachyury transcription regulatory network and compare the consequences of brachyury degradation with transcriptional CDK inhibition. Brachyury defines the chordoma super-enhancer landscape, autoregulates through binding its super-enhancer, and its locus forms a transcriptional condensate. Both transcriptional CDK inhibition and brachyury degradation disrupt brachyury autoregulation, leading to loss of its transcriptional condensate and transcriptional program. Compared with transcriptional CDK inhibition which globally downregulates transcription leading to cell death, brachyury degradation is much more selective, inducing senescence and sensitizing cells to anti-apoptotic inhibition. These data suggest that brachyury downregulation is a core tenet of transcriptional CDK inhibition and motivates developing strategies to target brachyury and its autoregulatory feedback loop.

Citation Format: Hadley E. Sheppard, Alessandra Dall'Agnese, Woojun D. Park, Hamza Shamim, Julien Dubrulle, Hannah L. Johnson, Fabio Stossi, Patricia Cogswell, Josh Sommer, Joan Levy, Tanaz Sharifnia, Mathias J. Wawer, Paul A. Clemons, Behnam Nabet, Nathanael S. Gray, Stuart L. Schreiber, Paul Workman, Richard A. Young, Charles Y. Lin. Targeted brachyury degradation disrupts a highly specific autoregulatory program controlling chordoma cell identity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB216.

Targeted brachyury degradation disrupts a highly specific autoregulatory program controlling chordoma cell identity

Chordomas are rare spinal tumors addicted to expression of the developmental transcription factor brachyury. In chordomas, brachyury is super-enhancer associated and preferentially downregulated by pharmacologic transcriptional CDK inhibition, leading to cell death. To understand the underlying basis of this sensitivity, we dissect the brachyury transcription regulatory network and compare the consequences of brachyury degradation with transcriptional CDK inhibition. Brachyury defines the chordoma super-enhancer landscape and autoregulates through binding its super-enhancer, and its locus forms a transcriptional condensate. Transcriptional CDK inhibition and brachyury degradation disrupt brachyury autoregulation, leading to loss of its transcriptional condensate and transcriptional program. Compared with transcriptional CDK inhibition, which globally downregulates transcription, leading to cell death, brachyury degradation is much more selective, inducing senescence and sensitizing cells to anti-apoptotic inhibition. These data suggest that brachyury downregulation is a core tenet of transcriptional CDK inhibition and motivates developing strategies to target brachyury and its autoregulatory feedback loop.

Brachyury defines the chordoma super-enhancer landscape

Brachyury autoregulates through a transcriptional condensate

CDK7/12/13i and brachyury degradation target the brachyury transcriptional condensate

Brachyury degradation inhibits chordoma identity genes and induces senescence

Abstract 3086: SINE compounds demonstrated potent anti-cancer activity in PDX mouse models of chordoma

Introduction: Chordoma is an ultra-rare cancer found in the base of the skull and the mobile spine that originates from embryonic remnants of the notochord. It is often resistant to standard chemotherapy and most systemic anti-cancer treatment, and surgical removal followed by radiation therapy remains the mainstay of current treatment. However, due to the difficult location of chordoma, complete surgical removal is not always possible. In addition, chordoma has a high rate of metastasis and recurrence. Therefore, novel and effective treatment options for chordoma are needed. Selective inhibitor of nuclear export (SINE) compounds selinexor and eltanexor are a class of novel oral drugs that target XPO1 (exportin-1/ CRM1) and exhibit anti-cancer activity across a wide range of solid and hematological malignancies. In July 2019, selinexor was approved by the US FDA to treat patients with multiple myeloma. To investigate the preclinical efficacy and tolerability of SINE compounds in chordoma, two PDX (patient derived xenograft) mouse models of chordoma were tested.

Methods: Two SINE drugs, selinexor at 5 mg/kg x 4 times a week and eltanexor at 10 mg/kg x 5 times a week, alone or in combination with bortezomib were used to treat chordoma CF466 and SF8894 PDX mouse models. CF466 PDX was derived from a patient with metastatic sacral chordoma whereas SF8894 PDX was derived from a patient with recurrent clival chordoma. Tumor volume and mouse body weight were monitored during the study. Tumors were collected at the end of 6 weeks of the study for histological, and immunohistochemistry (IHC)-based biomarker analyses.

Results: Both selinexor and eltanexor demonstrated potent anti-cancer activity compared to controls. Tumor growth inhibition (TGI) of selinexor was 58% and 78% in the CF466 and SF8894 models, respectively, and TGI of eltanexor was 55% in the SF8894 model. No significant difference in body weight was observed among different treatment groups. Bortezomib did not exhibit anti-tumor activity in these models nor did it have additive/synergistic effects when combined with selinexor or eltanexor. CF466 tumors from mice treated with selinexor showed increased apoptosis, decreased cell proliferation and lowered cell density when compared with the controls. In addition, IHC analysis showed that selinexor treatment increased nuclear retention of eIF4E and tumor suppressor proteins APC, SMAD4 and FOXO3A, and decreased the expression of proteins that may play a role in chordoma tumor biology, such as SHH, GLI1 and SOX9.

Conclusions: SINE compounds effectively inhibit tumor growth in PDX mouse models of chordoma. The anti-cancer effects are likely achieved through regulation of multiple signaling pathways. Further investigation of SINE compounds as treatment options for chordoma is warranted.

Citation Format: Hua Chang, Leah Henegar, Trinayan Kashyap, Thaddeus J. Unger, Sharon Shacham, Josh Sommer, Patty Cogswell, Stacy Fechner, Michael J. Wick, Joan Levy, Yosef Landesman. SINE compounds demonstrated potent anti-cancer activity in PDX mouse models of chordoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3086.

Small-molecule targeting of brachyury transcription factor addiction in chordoma

Chordoma is a primary bone cancer with no approved therapy1. The identification of therapeutic targets in this disease has been challenging due to the infrequent occurrence of clinically actionable somatic mutations in chordoma tumors2,3. Here we describe the discovery of therapeutically targetable chordoma dependencies via genome-scale CRISPR-Cas9 screening and focused small-molecule sensitivity profiling. These systematic approaches reveal that the developmental transcription factor T (brachyury; TBXT) is the top selectively essential gene in chordoma, and that transcriptional cyclin-dependent kinase (CDK) inhibitors targeting CDK7/12/13 and CDK9 potently suppress chordoma cell proliferation. In other cancer types, transcriptional CDK inhibitors have been observed to downregulate highly expressed, enhancer-associated oncogenic transcription factors4,5. In chordoma, we find that T is associated with a 1.5-Mb region containing 'super-enhancers' and is the most highly expressed super-enhancer-associated transcription factor. Notably, transcriptional CDK inhibition leads to preferential and concentration-dependent downregulation of cellular brachyury protein levels in all models tested. In vivo, CDK7/12/13-inhibitor treatment substantially reduces tumor growth. Together, these data demonstrate small-molecule targeting of brachyury transcription factor addiction in chordoma, identify a mechanism of T gene regulation that underlies this therapeutic strategy, and provide a blueprint for applying systematic genetic and chemical screening approaches to discover vulnerabilities in genomically quiet cancers.

Abstract 1949: A compound screen reveals potential novel therapeutic targets for chordoma: Metabolic stress response and epigenetic control of brachyury

Chordoma is a rare bone cancer, showing notochordal differentiation, that develops in axial skeleton in adults and children. Patients have a median survival of 7 years and radical surgical resection is the main treatment for this morbid disease, which does not respond to cytotoxic chemotherapy. We have previously demonstrated that EGFR inhibitors represent the almost unique family of kinase inhibitors to exert an effect on chordoma cell lines proliferation. However not all cell lines respond to these agents and drug resistance is likely to occur. Genomic studies have revealed that chordomas do not harbor recurrent alterations in kinases whereas chromatin-remodelling genes are altered in at least 20% of cases. The transcription factor brachyury (T) is the diagnostic hallmark of chordoma and is strongly implicated in its pathogenesis. T is regulated during embryonic development at the epigenetic level, suggesting that epigenetic inhibitors may represent a novel therapeutic approach for this disease. In this study, we have undertaken a medium throughput focused compound screen (n=91) using validated small molecule inhibitors of enzymes involved in chromatin biology and metabolic pathways. The alamar blue assay was employed to assess cell viability. Screening revealed activity in a number of compounds targeting the jumonji domain-containing lysine demethylases, including GSK-J4 and KDOBA67, two structurally closely related compounds that mainly target KDM6A (aka UTX) and KMD6B (JMJD3). These compounds were effective in all five chordoma cell lines (UCH1, UCH2, MUG-Chor, UM-Chor, UCH7) tested. In contrast to EGFR inhibitors, these compounds induced downregulation of T at the transcriptional and protein level. Preliminary results suggest this is achieved via the induction of a metabolic stress response as well as through the epigenetic regulation of T, the latter being brought by increased levels of H3K27me3. We also found that Halofuginone, a highly specific inhibitor of the enzyme glutamyl-prolyl tRNA synthetase already tested in phase I autoimmunity clinical trials, induced a metabolic stress response, similar to KDM6 inhibitors, in all chordoma cell lines. Moreover, Halofuginone treatment of a chordoma PDX model demonstrated 44% tumor growth inhibition (p=0.0052). In conclusion, we have identified epigenetic and metabolic pathways that represent potential novel targets for the treatment of chordoma.

Citation Format: Lucia Cottone, Edward Hookway, Graham Wells, Lorena Ligammari, Patrick Lombard, Ralph Mazitschek, Josh Sommer, Udo Oppermann, Adrienne M. Flanagan. A compound screen reveals potential novel therapeutic targets for chordoma: Metabolic stress response and epigenetic control of brachyury [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1949.

How well are Swiss French physicians prepared for future practice in primary care?

BACKGROUND

Moving from postgraduate training into independent practice represents a major transition in physicians' professional life. Little is known about how Swiss primary care graduates experience such a transition. The aim of this study was to explore the extent to which primary care physicians who recently set up private practice felt prepared to work as independent practitioners.

METHODS

We conducted 7 focus groups among recently established (≤ 5 years) primary care physicians in Switzerland. Questions focused on positive and negative aspects of setting up a practice, and degree of preparedness. Transcripts were analysed according to organisational socialisation and work role transition frameworks.

RESULTS

Participants felt relatively well prepared for most medical tasks except for some rheumatologic, minor traumatology, ENR, skin and psychiatric aspects. They felt unprepared for non clinical tasks such as office, insurance and medico-legal management issues and did not anticipate that the professional networking outside the hospital would be so important to their daily work. They faced dilemmas opposing professional values to the reality of practice which forced them to clarify their professional roles and expectations. Adjustment strategies were mainly informal.

CONCLUSION

Although the postgraduate primary care curriculum is longer in Switzerland than in most European countries, it remains insufficiently connected with the reality of transitioning into independent practice, especially regarding role development and management tasks. A greater proportion of postgraduate training, with special emphasis on these issues, should take place directly in primary care.

Best practices for the management of local-regional recurrent chordoma: a position paper by the Chordoma Global Consensus Group

Chordomas are rare, malignant bone tumors of the skull-base and axial skeleton. Until recently, there was no consensus among experts regarding appropriate clinical management of chordoma, resulting in inconsistent care and suboptimal outcomes for many patients. To address this shortcoming, the European Society of Medical Oncology (ESMO) and the Chordoma Foundation, the global chordoma patient advocacy group, convened a multi-disciplinary group of chordoma specialists to define by consensus evidence-based best practices for the optimal approach to chordoma. In January 2015, the first recommendations of this group were published, covering the management of primary and metastatic chordomas. Additional evidence and further discussion were needed to develop recommendations about the management of local-regional failures. Thus, ESMO and CF convened a second consensus group meeting in November 2015 to address the treatment of locally relapsed chordoma. This meeting involved over 60 specialists from Europe, the United States and Japan with expertise in treatment of patients with chordoma. The consensus achieved during that meeting is the subject of the present publication and complements the recommendations of the first position paper.

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.

A population-based study of the association between dysglycaemia and hearing loss in middle age

AIMS

To investigate the independent associations between hearing loss and dysglycaemia in a sample of middle-aged adults, including separate analysis of those aged < 60 years.

METHODS

The first 2023 participants in the cross-sectional Busselton Health Ageing Survey were assessed for hearing loss ≥ 26 dB (better ear) for four-frequency average (4FA) of pure-tone thresholds at 500, 1000, 2000 and 4000 Hz, and high-frequency average (HFA) of pure-tone thresholds at 4000 and 8000 Hz.

RESULTS

Valid data from 1864 participants in the Busselton Health Ageing Survey [92.1%; mean ± sd age 56.2 ± 5.5 years, 46.0% men, 120 (7.0%) with diabetes, 274 (14.7%) with prediabetes] were analysed, of whom 103 (5.5%) had four-frequency average hearing loss and 561 (30.1%) had high-frequency average hearing loss. In multivariable analyses, glycaemic status was not independently associated with four-frequency or high-frequency average hearing loss. In the 1286 participants aged < 60 years, there was no relationship between dysglycaemia and high-frequency average hearing loss, but the prevalence of four-frequency average hearing loss increased from 2.3% (95% CI 1.5-3.4) in participants with normoglycaemia to 5.7% (95% CI 3.0-10.6) in those with prediabetes and 10.2% (4.2-21.5) in those with diabetes (trend P = 0.003). In multivariable analysis with normoglycaemia as reference, the odds ratios for four-frequency average hearing loss were 2.84 (95% CI 1.29-6.27) for prediabetes and 5.93 (95% CI 1.67-21.05) for diabetes (P ≤ 0.01) in the < 60 year age group.

CONCLUSIONS

There was progressively increasing mid-range hearing loss with worsening glucose tolerance in younger individuals, suggesting dysglycaemia-associated early-onset presbycusis.

Classic IL-6R signalling is dispensable for intestinal epithelial proliferation and repair

Inflammatory bowel disease is characterized by disturbed cytokine signalling in the mucosa. Inhibition of the proinflammatory interleukin (IL)-6 pathway is a promising new therapeutic strategy, but safety concerns arise as IL-6 signalling also contributes to epithelial repair of the intestinal mucosa. To which extent IL-6 classic or trans-signalling contributes to intestinal repair remains elusive. We tested the influence of IL-6 classic signalling on intestinal repair and proliferation. Whereas IL-6 induced STAT3 phosphorylation in the colonic cancer cell lines, primary non-malignant intestinal organoids did not respond to IL-6 classic signalling. Mice deficient in intestinal IL-6R (IL-6R^ΔIEC mice) did not display increased susceptibility to acute dextran sulfate sodium (DSS)-induced colitis. In the azoxymethane DSS model IL-6R^ΔIEC mice were not protected from inflammation-induced carcinogenesis but showed comparable tumor load to wild-type mice. These data indicate that classic signalling is not the major pathway to transduce IL-6 stimuli into the intestinal epithelium.

Abstract 627: Establishment and characterization of a panel of cell-based and patient-derived chordoma tumor models

Background: Chordoma is a rare cancer (0.08 per 100k/yr) that originates from the notochord and develops in the skull and spine. Treatment options for chordoma include resection and local radiation therapy; however, recurrence rates following treatment are high and the majority of patients ultimately succumb to the disease. Currently there are no approved chemotherapy options for chordoma, and effective treatment options for patients with recurrent or advanced disease are limited. Recent molecular analyses of chordoma have revealed multiple tractable therapeutic targets, providing rationale for new systemic therapies. However, lack of relevant, validated chordoma models has limited preclinical evaluation. To address this need, the Chordoma Foundation and START have collaborated to establish, bank and characterize chordoma tumor models derived from patient samples and established cell lines.

Methods: Chordoma patients undergoing resection or biopsy procedures are identified and consented by the Chordoma Foundation under an IRB-approved protocol; tissue is shipped to START and implanted into immune-deficient mice for patient-derived xenograft (PDX) model establishment and banking. Similarly, models from immortalized chordoma cell lines have been established and banked, along with established PDX chordoma models from START or collaborators. Banked PDX models are anonymously linked to available patient clinical information. All chordoma models are subjected to immunohistochemistry (IHC) to confirm histology and presence of brachyury, a protein highly expressed in chordoma tumors. Following validation, models are used at START for drug sensitivity studies and available to investigators for characterization studies.

Results: To date, clinical samples from five chordoma patients have been implanted and two PDX models designated CF322 and CF345 have been established. In addition, xenograft models from the UCH-1 and UCH-2 chordoma cell lines have been established at START. PDX models previously developed at START (ST087) and UCSF (SF8894) have also been validated and banked. Drug sensitivity studies have been initiated these two and the U-CH1 models evaluating agents selected and prioritized through a peer review process established by the Chordoma Foundation. Nominations for additional test agents from academic and industry collaborators are reviewed on a rolling basis and evaluation of selected therapies is funded by the Chordoma Foundation.

Conclusion: We have established a collaboration to create, bank and characterize a panel of preclinical chordoma tumor models originating from patient samples and established cell lines. To date we have generated three chordoma models available for drug sensitivity studies. This panel of models is intended to serve as a shared resource to the chordoma research community to enable more rapid preclinical evaluation of therapeutic hypotheses.

Citation Format: Michael J. Wick, Melissa Rundle, Lizette Gamez, Armando Diaz, Josh Sommer, Patricia Cogswell, Byron Hann, Joanna Phillips, Kyriakos P. Papadopoulos. Establishment and characterization of a panel of cell-based and patient-derived chordoma tumor models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 627.

Neural pathways of embarrassment and their modulation by social anxiety

While being in the center of attention and exposed to other's evaluations humans are prone to experience embarrassment. To characterize the neural underpinnings of such aversive moments, we induced genuine experiences of embarrassment during person-group interactions in a functional neuroimaging study. Using a mock-up scenario with three confederates, we examined how the presence of an audience affected physiological and neural responses and the reported emotional experiences of failures and achievements. The results indicated that publicity induced activations in mentalizing areas and failures led to activations in arousal processing systems. Mentalizing activity as well as attention towards the audience were increased in socially anxious participants. The converging integration of information from mentalizing areas and arousal processing systems within the ventral anterior insula and amygdala forms the neural pathways of embarrassment. Targeting these neural markers of embarrassment in the (para-)limbic system provides new perspectives for developing treatment strategies for social anxiety disorders.

Building a global consensus approach to chordoma: a position paper from the medical and patient community

Chordomas are very rare bone malignant tumours that have had a shortage of effective treatments for a long time. New treatments are now available for both the local and the metastatic phase of the disease, but the degree of uncertainty in selecting the most appropriate treatment remains high and their adoption remains inconsistent across the world, resulting in suboptimum outcomes for many patients. In December, 2013, the European Society for Medical Oncology (ESMO) convened a consensus meeting to update its clinical practice guidelines on sarcomas. ESMO also hosted a parallel consensus meeting on chordoma that included more than 40 chordoma experts from several disciplines and from both sides of the Atlantic, with the contribution and sponsorship of the Chordoma Foundation, a global patient advocacy group. The consensus reached at that meeting is shown in this position paper.

Providers Expectations on Telemedicine: A Qualitative Research in a Large Healthcare Network of Latin America

The benefits of Telemedicine make it a viable, reliable and useful discipline for dispensing health care. This qualitative study is aimed to understand the expectations, opinions and previous knowledge of the professionals about telemedicine at the Hospital Italiano de Buenos Aires.

RESULTS

Professionals realize that Telemedicine is inserted into their usual practice in an informal way. They consider telemedicine as an alternative to the traditional delivery of health care, but are afraid of their role in health care is undermined. Professionals point out very specific applications of Telemedicine such as monitoring the health of patients remotely, drug doses adjustments and sharing clinical information.

CONCLUSION

Results suggest that professionals are not familiar with telemedicine and will be necessary to develop a training plan before implementation.

Identification of repurposed small molecule drugs for chordoma therapy

Chordoma is a rare, slow growing malignant tumor arising from remnants of the fetal notochord. Surgery is the first choice for chordoma treatment, followed by radiotherapy, although postoperative complications remain significant. Recurrence of the disease occurs frequently due to the anatomy of the tumor location and violation of the tumor margins at the initial surgery. Currently, there are no effective drugs available for patients with chordoma. Due to the rarity of the disease, there is limited opportunity to test agents in clinical trials and no concerted effort to develop agents for chordoma in the pharmaceutical industry. To rapidly and efficiently identify small molecules that inhibit chordoma cell growth, we screened the NCGC Pharmaceutical Collection (NPC) containing approximately 2800 clinically approved and investigational drugs at 15 different concentrations in chordoma cell lines, U-CH1 and U-CH2. We identified a group of drugs including bortezomib, 17-AAG, digitoxin, staurosporine, digoxin, rubitecan, and trimetrexate that inhibited chordoma cell growth, with potencies from 10 to 370 nM in U-CH1 cells, but less potently in U-CH2 cells. Most of these drugs also induced caspase 3/7 activity with a similar rank order as the cytotoxic effect on U-CH1 cells. Cantharidin, digoxin, digitoxin, staurosporine, and bortezomib showed similar inhibitory effect on cell lines and 3 primary chordoma cell cultures. The combination treatment of bortezomib with topoisomerase I and II inhibitors increased the therapeutic potency in U-CH2 and patient-derived primary cultures. Our results provide information useful for repurposing currently approved drugs for chordoma and potential approach of combination therapy.

Structural changes of central white matter tracts in Kennedy's disease - a diffusion tensor imaging and voxel-based morphometry study

OBJECTIVES

Spinobulbar muscular atrophy [Kennedy's disease (KD)] is a rare X-linked neurodegenerative disorder of mainly spinal and bulbar motoneurons. Recent studies suggest a multisystem character of this disease. The aim of this study was to identify and characterize structural changes of gray (GM) and white matter (WM) in the central nervous system.

MATERIAL AND METHODS

Whole-brain-based voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analyses were applied to MRI data of eight genetically proven patients with KD and compared with 16 healthy age-matched controls.

RESULTS

Diffusion tensor imaging analysis showed not only decreased fractional anisotropy (FA) values in the brainstem, but also widespread changes in central WM tracts, whereas VBM analysis of the WM showed alterations primarily in the brainstem and cerebellum. There were no changes in GM volume. The FA value decrease in the brainstem correlated with the disease duration.

CONCLUSION

Diffusion tensor imaging analysis revealed subtle changes of central WM tract integrity, while GM and WM volume remained unaffected. In our patient sample, KD had more extended effects than previously reported. These changes could either be attributed primarily to neurodegeneration or reflect secondary plastic changes due to atrophy of lower motor neurons and reorganization of cortical structures.

Xerostomia after radiotherapy. What matters--mean total dose or dose to each parotid gland?

PURPOSE

Xerostomia is a debilitating side effect of radiotherapy in patients with head and neck cancer. We undertook a prospective study of the effect on xerostomia and outcomes of sparing one or both parotid glands during radiotherapy for patients with squamous cell carcinoma of the head and neck.

METHODS AND MATERIALS

Patients with locally advanced squamous cell carcinoma of the head and neck received definitive (70 Gy in 2 Gy fractions) or adjuvant (60-66 Gy in 2 Gy fractions) curative-intent radiotherapy using helical tomotherapy with concurrent chemotherapy if appropriate. Group A received < 26 Gy to the left and right parotids and group B received < 26 Gy to either parotid.

RESULTS

The study included 126 patients; 114 (55 in group A and 59 in group B) had follow-up data. There were no statistically significant differences between groups in disease stage. Xerostomia was significantly reduced in group A vs. group B (p = 0.0381). Patients in group A also had significantly less dysphagia. Relapse-free and overall survival were not compromised in group A: 2-year relapse-free survival was 86% vs. 72% in group B (p = 0.361); 2-year overall survival was 88% and 76%, respectively (p = 0.251).

CONCLUSION

This analysis suggests that reducing radiotherapy doses to both parotid glands to < 26 Gy can reduce xerostomia and dysphagia significantly without compromising survival. Sparing both parotids while maintaining target volume coverage and clinical outcome should be the treatment goal and reporting radiotherapy doses delivered to the individual parotids should be standard practice.

[Tomorrow's family doctor]

The profession of family doctor will undergo profound changes in the coming decade due to external, political, demographic and societal developments. Changes will also occur from within the profession affecting its content and its functioning. Other influences, in addition to generational developments (reduced working hours, feminisation, revaluation of the work-life balance), will come from collaboration with new professions, news structures as well as technical and human progress. In this transitional period it is important to uphold core values of family medicine, in particular coordination, continuity of care and the global approach to patients. In training future family doctors we must both prepare them for new skills and roles, and continue to share the core values with them.

Isolation and characterization of eight polymorphic microsatellite markers for the migratory characiform fish, Salminus brasiliensis

Eight polymorphic microsatellite loci were isolated and characterized for the migratory freshwater fish Salminus brasiliensis (Characiformes) and tested on 67 individuals from nine geographically distant locations along the Paraná Basin. The number of alleles per locus ranged from four to 14, with observed heterozygosity estimates ranging from 0·15 to 0·79.

[Teaching about practice guidelines: osteoporosis]

Family physicians need to know how to teach students practical guidelines for frequent diseases such as osteoporosis. After the age of 50 years, the risk for osteoporotic fractures is 50% for women and 20% for men. It is therefore useful to prevent and screen for osteoporosis. Family physicians need to know how to recognize the clinical and biological risk factors for osteoporosis; they must know when to request a bone densitometry, the "gold standard" for diagnosis. They must also be able to integrate these factors within the clinical context to evaluate the absolute risk of osteoporosis-related fracture that determines the need for specific treatment. Numerous treatments with proven efficacy to reduce global fractures are available but it is important to know their different indications, risk/benefits and potential harmful side-effects.

[Learning about family medicine and the doctor-patient relationship: student views]

The five university institutes/units for family medicine in Switzerland are now responsible for teaching family medicine to medical students, particularly through the introductory cleckship in primary care in the 2nd year. During four half-days, the students attend the office of a family doctor and discover the characteristics of family medicine according to the definition of the World Association of Family Doctors (WONCA). This article shows how these training sessions are a profound and enriching learning experience for students. Different skills are presented and are illustrated by extracts from the reports students write at the end of the four half-days.