Sarcomas are malignant soft tissue and bone tumours affecting adults, adolescents and children. They represent a morphologically heterogeneous class of tumours and some entities lack defining histopathological features. Therefore, the diagnosis of sarcomas is burdened with a high inter-observer variability and misclassification rate. Here, we demonstrate classification of soft tissue and bone tumours using a machine learning classifier algorithm based on array-generated DNA methylation data. This sarcoma classifier is trained using a dataset of 1077 methylation profiles from comprehensively pre-characterized cases comprising 62 tumour methylation classes constituting a broad range of soft tissue and bone sarcoma subtypes across the entire age spectrum. The performance is validated in a cohort of 428 sarcomatous tumours, of which 322 cases were classified by the sarcoma classifier. Our results demonstrate the potential of the DNA methylation-based sarcoma classification for research and future diagnostic applications.

Solitary fibrous tumor is a mesenchymal tumor of fibroblastic type, which can affect any region of the body. Recently, a recurrent gene fusion NAB2-STAT6 has been identified as molecular hallmark. The NAB2-STAT6 fusion leads to EGR1 activation and transcriptional deregulation of EGR1-dependent target genes and is a driving event in initiation of SFT. In this study, we report the clinicopathologic and RT-PCR findings and evaluated expression of STAT6 and EGR1 protein in a cohort of 28 SFTs. 28 patients with a median age of 54 years were included with SFTs originating at different sites, most occurring in the lung and pleura (9, 32%), 5 in soft tissues of the lower extremities (18%) and 5 in the head and neck (18%). For detection of the NAB2-STAT6 fusion gene, RT-PCR was performed using RNA extracted from formalin-fixed and paraffin-embedded tissues. Immunohistochemistry was performed on all cases with antibodies against STAT6 and EGR1. All patients were treated by surgery, 3 with adjuvant chemo- or radiotherapy. Follow-up data of 18 patients could be obtained of which 2 patients died of metastatic disease 13 months and 52 years after first diagnosis. Sixteen patients have no evidence of disease with a median follow up of 29.5 months (range 7 – 120 months). NAB2-STAT6 fusion transcripts were found in 19/28 cases (68%). The most common fusion was between NAB2 exon 4 and STAT6 exon 3 (11/19, 58%), mainly occurring in pleuropulmonary lesions. All cases showed strong nuclear expression of STAT6 (28/28, 100%) while EGR1 showed low-level variable nuclear expression in all samples, comparable with the EGR1 expression results of the control group. The identification of the NAB2-STAT6 fusion in SFTs can provide important diagnostic information, especially in cases with aberrant morphology or when biopsy material is limited. STAT6 immunohistochemistry is another useful tool in diagnosing SFT. EGR1 immunohistochemistry indicates low-level protein expression in accordance with EGR1 activation due to distorted NAB2 activity. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_224

Purpose: The aim of this study is to investigate anaplastic lymphoma kinase (ALK) protein expression and underlying genetic aberrations in rhabdomyosarcoma (RMS), with special attention to clinical and prognostic implications. Patients and Methods: A total of 189 paraffin-embedded RMS tumor specimens from 145 patients were collected on tissue microarray. ALK protein expression was evaluated by immunohistochemistry. ALK gene (2p23) copy number and translocations were determined by in situ hybridization. cDNA sequencing of the receptor tyrosine kinase domain of the ALK gene was assessed in 43 samples. Results: Strong cytoplasmic ALK protein expression was more frequently observed in alveolar RMS (ARMS) than in embryonal RMS (ERMS) (81% v 32%, respectively; P < .001). ALK gene copy number gain was detected in the vast majority of ARMS (88%), compared with 52% of ERMS (P < .001). ALK copy number correlated with protein expression in primary tumors (n = 107). We identified one point mutation (2%) and seven tumors harboring whole exon deletions (16%). In ERMS, specific ALK gain in the primary tumor correlated with metastatic disease (100% in metastatic disease v 29% in nonmetastatic disease; P = .004) and poor disease-specific survival (5-year disease-specific survival: 62% v 82% for nonspecific or no gain; P = .046). Conclusion: Because ALK aberrations on genomic and protein levels are frequently found in RMSs, in particular ARMS, and are associated with disease progression and outcome in ERMS, ALK may play a role in tumor biology and may provide a potential therapeutic target for these tumors. Future research should aim at the oncogenic role of ALK and the potential effect of ALK inhibitors in RMS.

Expression and clinical association of programmed cell death-1, programmed death-ligand-1 and CD8 + lymphocytes in primary sarcomas is subtype dependent Expression and clinical association of programmed cell death-1, programmed death-ligand-1 and CD8+ lymphocytes in primary sarcomas is subtype dependent

The insulinlike growth factor 1 receptor (IGF-1R) is a new target for the treatment of breast cancer. Patients with breast cancer lesions that express IGF-1R may benefit from treatment with anti–IGF-1R antibodies. Therefore, the aim of the present study was to develop a noninvasive, in vivo imaging method, using radiolabeled antibodies, to visualize IGF-1R expression. Methods: R1507 is a monoclonal antibody directed against the IGF-1R. In vitro, the affinity and internalization kinetics of ¹¹¹In-R1507 were determined using the IGF-1R–expressing triple-negative breast cancer cell line SUM149. In vivo, the pharmacodynamics of ¹¹¹In-R1507 and ¹²⁵I-R1507 were determined in mice with subcutaneous SUM149 tumors. ¹¹¹In-R1507 SPECT and ⁸⁹Zr-R1507 PET images of mice with subcutaneous SUM149 tumors were acquired at 1, 3, and 7 d after injection. Results: ¹¹¹In-R1507 (concentration required to inhibit binding by 50%, 0.1 nM) was slowly internalized by SUM149 cells. ¹¹¹In-R1507 specifically and efficiently accumulated in the SUM149 xenografts: the tumor uptake was 20 percentage injected dose per gram (%ID/g), 33 %ID/g, and 31 %ID/g at 1, 3, and 7 d after injection, respectively. ¹²⁵I-R1507 accumulated in the tumor less efficiently. Small-animal SPECT and small-animal PET of mice clearly visualized the subcutaneous SUM149 xenograft, with increasing contrast at later time points. Conclusion: ¹¹¹In-R1507 and ⁸⁹Zr-R1507 are new tracers to noninvasively determine IGF-1R expression in vivo in breast cancer xenografts using SPECT and PET. In the future, these techniques may enable patient selection for IGF-1R–targeted therapy.