[Gastrointestinal stromal tumors : Where do we stand?] / Gastrointestinale Stromatumoren : Wo stehen wir?

For more than 20 years gastrointestinal stromal tumors (GIST) have been a paradigm for a targeted treatment with tyrosine kinase inhibitors. A fundamental prerequisite for a neoadjuvant or adjuvant treatment of localized GIST or an additive treatment of metastatic GIST is the molecular typing of tumors, ideally at the initial diagnosis. In addition, the possibility of a hereditary or syndromic predisposition must be considered because this results in consequences for the treatment and a different follow-up strategy.

PD-L1 on large extracellular vesicles is a predictive biomarker for therapy response in tissue PD-L1-low and -negative patients with non-small cell lung cancer.

Immunotherapy has revolutionized the treatment of patients with non-small cell lung cancer (NSCLC). High expression of tissue PD-L1 (tPD-L1) is currently the only approved biomarker for predicting treatment response. However, even tPD-L1 low (1-49%) and absent (<1%) patients might benefit from immunotherapy but, to date, there is no reliable biomarker, that can predict response in this particular patient subgroup. This study aimed to test whether tumour-associated extracellular vesicles (EVs) could fill this gap. Using NSCLC cell lines, we identified a panel of tumour-related antigens that were enriched on large EVs (lEVs) compared to smaller EVs. The levels of lEVs carrying these antigens were significantly elevated in plasma of NSCLC patients (n = 108) and discriminated them from controls (n = 77). Among the tested antigens, we focused on programmed cell death ligand 1 (PD-L1), which is a well-known direct target for immunotherapy. In plasma lEVs, PD-L1 was mainly found on a population of CD45- /CD62P+ lEVs and thus seemed to be associated with platelet-derived vesicles. Patients with high baseline levels of PD-L1+ lEVs in blood showed a significantly better response to immunotherapy and prolonged survival. This was particularly true in the subgroup of NSCLC patients with low or absent tPD-L1 expression, thus identifying PD-L1-positive lEVs in plasma as a novel predictive and prognostic marker for immunotherapy.

KIT ATP-Binding Pocket/Activation Loop Mutations in GI Stromal Tumor: Emerging Mechanisms of Kinase Inhibitor Escape.

PURPOSE: Imatinib resistance in GI stromal tumors (GISTs) is primarily caused by secondary KIT mutations, and clonal heterogeneity of these secondary mutations represents a major treatment obstacle. KIT inhibitors used after imatinib have clinical activity, albeit with limited benefit. Ripretinib is a potent inhibitor of secondary KIT mutations in the activation loop (AL). However, clinical benefit in fourth line remains limited and the molecular mechanisms of ripretinib resistance are largely unknown. PATIENTS AND METHODS: Progressing lesions of 25 patients with GISTs refractory to ripretinib were sequenced for KIT resistance mutations. Resistant genotypes were validated and characterized using novel cell line models and in silico modeling. RESULTS: GISTs progressing on ripretinib were enriched for secondary mutations in the ATP-binding pocket (AP), which frequently occur in cis with preexisting AL mutations, resulting in highly resistant AP/AL genotypes. AP/AL mutations were rarely observed in a cohort of progressing GIST samples from the preripretinib era but represented 50% of secondary KIT mutations in patients with tumors resistant to ripretinib. In GIST cell lines harboring secondary KIT AL mutations, the sole genomic escape mechanisms during ripretinib drug selection were AP/AL mutations. Ripretinib and sunitinib synergize against mixed clones with secondary AP or AL mutants but do not suppress clones with AP/AL genotypes. CONCLUSION: Our findings underscore that KIT remains the central oncogenic driver even in late lines of GIST therapy. KIT-inhibitor combinations may suppress resistance because of secondary KIT mutations. However, the emergence of KIT AP/AL mutations after ripretinib treatment calls for new strategies in the development of next-generation KIT inhibitors.

Trauma and sporadic desmoid tumor development: An approach toward real incidence and aspects of causality.

OBJECTIVES: The development of desmoid tumors (DT) is associated with trauma, which is an aspect with medicolegal relevance. The objective of this study was to analyze the proportion and type of trauma (surgical, blunt/fracture, implants), its lag time, and mutations of the CTNNB1 gene in patients with sporadic DT. METHODS: We analyzed a prospectively kept database of 381 females and 171 males, median age at disease onset 37.7 years (females) and 39.3 years (males) with a histologically confirmed DT. Patients with germline mutation of the APC gene were excluded. Details of the history particularly of traumatic injuries to the site of DT were provided by 501 patients. RESULTS: In 164 patients (32.7%), a trauma anteceding DT could be verified with a median lag time of 22.9 months (SD, 7.7 months; range, 9-44 months). A prior surgical procedure was relevant in 98 patients, a blunt trauma in 35 patients, a punctuated trauma (injections, trocar) in 18 patients, and site of an implant in 10 patients. In 220 patients, no trauma was reported (43.9%), and 58 females (11.6%) had a postpregnancy DT in the rectus abdominis muscle. In 42 patients (8.4%), data were inconclusive. The distribution of mutations in the CTNNB1 gene (codon 41 vs. 45) was similar in patients with and without a history of trauma before DT development. CONCLUSIONS: A significant subgroup of patients suffers from a trauma-associated DT, predominantly at a prior surgical site including implants to breast or groin, accounting for 77.9% of the cases, whereas blunt trauma was responsible in 22.1%. We found no data to support that trauma-associated DT have different molecular features in the CTNNB1 gene.

Immunohistochemical expression of TROP­2 (TACSTD2) on the urothelial carcinoma of the urinary bladder and other types of cancer.

In metastatic or locally advanced urothelial carcinoma (UC), therapeutic options have been limited to chemotherapy and immune checkpoint inhibitors. Novel targets and drugs such as antibody drug conjugates have been developed, and enfortumab vedotin targeting nectin-4 and sacituzumab govitecan (SG) targeting trophoblast cell surface antigen 2 (TROP-2), the protein product of the TACSTD2 gene, have been approved. The expression of TROP-2 was investigated within UC and other types of carcinomas, and within the tissue of different healthy organs to understand treatment responses and toxicities. The expression of TROP-2 in the tissues of 42 patients with UC, 13 patients with other types of cancer and in the normal tissues of 11 patients was retrospectively analyzed. Immunohistochemical staining of the TROP-2 protein was performed on a BenchMark ULTRA IHC/ISH System (Roche Tissue Diagnostics; Roche Diagnostics, Ltd.) according to accredited staining protocols in a routine immunohistochemistry accredited and certified facility of the laboratory of immunohistochemistry at the Institute of Pathology (Gerhard-Domagk Institute)- University Hospital Muenster (UKM)-Muenster-Germany]. Different expression levels of TROP-2 were observed, and the highest expression rate of TROP-2 was observed in UC, independent of the tumor stage. However, normal urothelial cells had similar expression levels. Except for ductal carcinoma in situ, the expression of TROP-2 was reduced in other types of cancer and in the healthy tissues from other organs, including pancreas, gall bladder, colon and prostate. Given the treatment response based on the expression level of TROP-2, SG would be effective in almost all cases of UC. However, it would also have an effect on the normal urothelium.

A Systematic Review and Illustrative Case Presentation of Low-Grade Myofibroblastic Sarcoma (LGMS) of the Extremities.

INTRODUCTION: Low-grade myofibroblastic sarcoma (LGMS) is a rare tumor entity which occurs in the subcutaneous and deep soft tissues; it is less common in the bone with a predilection for the extremities and the head and neck region. As confirming the diagnosis is difficult and treatment strategies are not standardized, we aimed to identify patient and tumor characteristics, and to summarize treatment strategies and their clinical outcomes to guide surgeons. METHODS: Included were full articles reporting patients with histology of LGMS in the extremities, excluding tumors of the trunk. All patients underwent surgery but with different extend, from marginal to wide resection. Included studies should inform about local recurrence, metastasis, or evidence of disease, depending on the surgical treatment. We conducted a structured search using MEDLINE (via PubMed), Web of Science, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) to identify studies on low-grade myofibroblastic sarcoma of the extremities. Study designs like randomized controlled trials, systematic reviews, prospective trials, retrospective studies, and case reports were included. Prospective studies and comparative studies were not available at all. Therefore, meta-analysis was not possible and statistical analysis was purely descriptive. RESULTS: Of the 789 studies identified from our initial search, 17 studies including 59 cases reported LGMS of the extremities with the surgical treatment and clinical outcome and were therefore analyzed. In addition, we present the rare case and surgical management of a 28-year-old male patient with residual LGMS of the thumb after an initial incomplete resection. The current literature suggests that a wide excision with R0 margins should be considered the standard treatment for LGMS. In cases where surgery leads to significant functional impairment, individual options like free tissue transfer from a donor site have to be considered. Therefore, we also present an illustrative case. For all selected case series and case reports, a high risk of confounding, selection bias, information bias, and reporting bias must be anticipated. Nevertheless, this systematic review provides a comprehensive overview on surgical treatment and clinical outcomes in LGMS surgery of the extremities.

Health related Quality of Life over time in German sarcoma patients. An analysis of associated factors - results of the PROSa study.

Introduction: Sarcomas are rare cancers and very heterogeneous in their location, histological subtype, and treatment. Health-Related Quality of Life (HRQoL) of sarcoma patients has rarely been investigated in longitudinal studies. Methods: Here, we assessed adult sarcoma patients and survivors between September 2017 and February 2020, and followed-up for one year in 39 study centers in Germany. Follow-up time points were 6 (t1) and 12 months (t2) after inclusion. We used a standardized, validated questionnaire (the European Organisation for Research and Treatment of Cancer Quality of Life Core Instrument (EORTC QLQ-C30) and explored predictors of HRQoL in two populations (all patients (Analysis 1), patients in ongoing complete remission (Analysis 2)) using generalized linear mixed models. Results: In total we included up to 1111 patients at baseline (915 at t1, and 847 at t2), thereof 387 participants were in complete remission at baseline (334 at t1, and 200 at t2). When analyzing all patients, HRQoL differed with regard to tumor locations: patients with sarcoma in lower extremities reported lower HRQoL values than patients with sarcomas in the upper extremities. Treatment which included radiotherapy and/or systemic therapy was associated with lower HRQoL. For patients in complete remission, smoking was associated with worse HRQoL-outcomes. In both analyses, bone sarcomas were associated with the worst HRQoL values. Being female, in the age group 55-<65 years, having lower socioeconomic status, and comorbidities were all associated with a lower HRQoL, in both analyses. Discussion: HRQoL increased partially over time since treatment and with sporting activities. HRQoL improved with time since treatment, although not in all domains, and was associated with lifestyle and socioeconomic factors. Bone sarcomas were the most affected subgroup. Methods to preserve and improve HRQoL should be developed for sarcoma patients.

Complete Metabolic Response to Combined Immune Checkpoint Inhibition after Progression of Metastatic Colorectal Cancer on Pembrolizumab: A Case Report.

DNA mismatch repair deficient (dMMR) and microsatellite instable (MSI) metastatic colorectal cancer (mCRC) can be successfully treated with FDA- and EMA-approved immune checkpoint inhibitors (ICI) pembrolizumab and nivolumab (as single agents targeting the anti-programmed cell death protein-1 (PD-1)) or combinations of a PD-1 inhibitor with ipilimumab, a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)-targeting antibody. The best treatment strategy beyond progression on single-agent ICI therapy remains unclear. Here, we present the case of a 63-year-old male with Lynch-syndrome-associated, microsatellite instability-high (MSI-H) mCRC who achieved a rapid normalization of his tumor markers and a complete metabolic remission (CMR), currently lasting for ten months, on sequential ICI treatment with the combination of nivolumab and ipilimumab followed by nivolumab maintenance therapy after progression on single-agent anti-PD-1 ICI therapy. The therapy was well-tolerated, and no immune-related adverse events occurred. To the best of our knowledge, this is the first case of a sustained metabolic complete remission in an MSI-H mCRC patient initially progressing on single-agent anti-PD-1 therapy. Thus, dMMR mCRC patients might benefit from sequential immune checkpoint regimens even with long-term responses. However, further sophistication of clinical algorithms for treatment beyond progression on single-agent ICI therapy in MSI-mCRC is urgently needed.

Acid-base homeostasis orchestrated by NHE1 defines the pancreatic stellate cell phenotype in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) progresses in an organ with a unique pH landscape, where the stroma acidifies after each meal. We hypothesized that disrupting this pH landscape during PDAC progression triggers pancreatic stellate cells (PSCs) and cancer-associated fibroblasts (CAFs) to induce PDAC fibrosis. We revealed that alkaline environmental pH was sufficient to induce PSC differentiation to a myofibroblastic phenotype. We then mechanistically dissected this finding, focusing on the involvement of the Na+/H+ exchanger NHE1. Perturbing cellular pH homeostasis by inhibiting NHE1 with cariporide partially altered the myofibroblastic PSC phenotype. To show the relevance of this finding in vivo, we targeted NHE1 in murine PDAC (KPfC). Indeed, tumor fibrosis decreased when mice received the NHE1-inhibitor cariporide in addition to gemcitabine treatment. Moreover, the tumor immune infiltrate shifted from granulocyte rich to more lymphocytic. Taken together, our study provides mechanistic evidence on how the pancreatic pH landscape shapes pancreatic cancer through tuning PSC differentiation.

Sarcoma Research with Cancer Registry Data: Data and Peculiarities of Germany in the Light of Other Countries.

INTRODUCTION: Sarcomas are documented in population-based and in clinic-associated databases. This study evaluated the status quo regarding the potential and obstacles of cancer registry-based research on sarcomas exemplified by Germany in comparison to similar databases in the US and Europe. Completeness and quality of data are discussed based on statistical analyses of a pooled data set established for the German Cancer Congress 2020. METHODS: We analyzed data derived from 16 German institutions (federal state cancer registries and some facility-based registries). Malignant sarcomas in adults diagnosed between 2000 and 2018 with information on histology were grouped according to the WHO classification of soft tissue and bone tumors. Descriptive analyses of the study population regarding the distribution of age, sex, histology, localization of primary tumors, and metastases were performed. Survival for the ten most frequent histological groups and UICC stages was evaluated according to Kaplan-Meier and Cox regression. Time interval between surgery and subsequent radiation was calculated. RESULTS: The initial data set contained 35,091 sarcomas. After several steps of data cleaning, 28,311 patients with known sex and unambiguous assignment to a histological subgroup remained (13,682 women and 14,629 men). Between 40 and 54 years, women were more likely to develop sarcomas, whereas in the older age groups more men were affected. Gastrointestinal stromal tumors, fibroblastic, and myofibroblastic tumors, smooth muscle tumors (mostly non-uterine leiomyosarcomas), and adipocytic tumors represented 48% of all sarcomas. Preferential sites for fibrosarcomas were the limbs, the trunk, and the head and neck region. The liposarcoma occurred most frequently on the trunk and limbs. Distant primary metastases were mostly located in the lung (43%), followed by the liver (14%), and bones (13%). Vascular and smooth muscle tumors showed the worst survival prognosis (5-year survival: approx. 15%, median survival approx. 8-16 months), whereas in low stages, the probability of survival of many sarcoma patients was beyond 5 years. Adjuvant radiotherapy was applied within 90 days in 71% of patients (n = 2,534). CONCLUSION: Our results correspond to the data from the literature. However, a lack of data quality and completeness hampers further meaningful analyses, especially nonspecific or missing information about morphology and stage. Compared to some other countries, a comprehensive database is presently missing in Germany. However, currently, there are important efforts and legislative initiatives to create a comprehensive database on a national level within the near future.

Radiomics of Tumor Heterogeneity in 18F-FDG-PET-CT for Predicting Response to Immune Checkpoint Inhibition in Therapy-Naïve Patients with Advanced Non-Small-Cell Lung Cancer.

We aimed to evaluate the predictive and prognostic value of baseline 18F-FDG-PET-CT (PET-CT) radiomic features (RFs) for immune checkpoint-inhibitor (CKI)-based first-line therapy in advanced non-small-cell lung cancer (NSCLC) patients. In this retrospective study 44 patients were included. Patients were treated with either CKI-monotherapy or combined CKI-based immunotherapy-chemotherapy as first-line treatment. Treatment response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST). After a median follow-up of 6.4 months patients were stratified into "responder" (n = 33) and "non-responder" (n = 11). RFs were extracted from baseline PET and CT data after segmenting PET-positive tumor volume of all lesions. A Radiomics-based model was developed based on a Radiomics signature consisting of reliable RFs that allow classification of response and overall progression using multivariate logistic regression. These RF were additionally tested for their prognostic value in all patients by applying a model-derived threshold. Two independent PET-based RFs differentiated well between responders and non-responders. For predicting response, the area under the curve (AUC) was 0.69 for "PET-Skewness" and 0.75 predicting overall progression for "PET-Median". In terms of progression-free survival analysis, patients with a lower value of PET-Skewness (threshold < 0.2014; hazard ratio (HR) 0.17, 95% CI 0.06-0.46; p < 0.001) and higher value of PET-Median (threshold > 0.5233; HR 0.23, 95% CI 0.11-0.49; p < 0.001) had a significantly lower probability of disease progression or death. Our Radiomics-based model might be able to predict response in advanced NSCLC patients treated with CKI-based first-line therapy.

KIT and PDGFRA Mutations and Survival of Gastrointestinal Stromal Tumor Patients Treated with Adjuvant Imatinib in a Randomized Trial.

PURPOSE: Limited data are available about the influence of KIT and PDGFRA mutations on overall survival (OS) of patients with gastrointestinal stromal tumor (GIST) treated with adjuvant imatinib. PATIENTS AND METHODS: The Scandinavian Sarcoma Group XVIII/AIO multicenter trial accrued 400 patients with a high risk for GIST recurrence after macroscopically complete surgery between February 4, 2004, and September 29, 2008. The patients received adjuvant imatinib 400 mg/day for either 1 year or 3 years based on random allocation. We analyzed using conventional sequencing KIT and PDGFRA mutations centrally from 341 (85%) patients who had localized, centrally confirmed GIST, and correlated the results with recurrence-free survival (RFS) and OS in exploratory analyses. RESULTS: During a median follow-up time of 10 years, 164 RFS events and 76 deaths occurred. Most patients were re-treated with imatinib when GIST recurred. Patients with KIT exon 11 deletion or indel mutation treated with 3 years of adjuvant imatinib survived longer than patients treated for 1 year [10-year OS 86% versus 64%, respectively; HR, 0.34; 95% confidence interval (CI), 0.15-0.72; P = 0.007], and also had longer RFS (10-year RFS 47% versus 29%; HR, 0.48; 95% CI, 0.31-0.74; P < 0.001). Patients with KIT exon 9 mutation had unfavorable OS regardless of the duration of adjuvant imatinib. CONCLUSIONS: Compared with 1 year of imatinib, 3 years of adjuvant imatinib led to 66% reduction in the estimated risk of death and a high 10-year OS rate in the subset of patients with a KIT exon 11 deletion/indel mutation.

Interdependence of SS18-SSX-driven YAP1 and ß-Catenin Activation in Synovial Sarcoma.

Synovial sarcoma, a rare malignant soft tissue tumor, is characterized by a specific chromosomal translocation t(X;18). The resulting chimeric SS18-SSX fusion protein drives synovial sarcoma pathogenesis by integrating into the BAF complex and dysregulating gene transcription. Because previous functional analyses revealed a connection between SS18-SSX and the activity of the transcriptional coregulators YAP1/TAZ and ß-catenin, respectively, this study examined a potential interdependence between these essential effector proteins in synovial sarcoma. In a large cohort of synovial sarcoma tissue specimens, IHC analyses revealed a substantial subset of synovial sarcoma with concurrent nuclear accumulation of YAP1/TAZ and ß-catenin. In vitro, small-molecule inhibitor treatment, RNAi-mediated knockdown, and vector-based overexpression assays demonstrated that YAP1, TAZ, and ß-catenin transcriptional activity is not only stimulated by the SS18-SSX fusion protein, but that they also mutually enhance each other's activation. These analyses showed the highest cooperative effect with overexpression of YAP1 in combination with ß-catenin. Coimmunoprecipitation experiments detected nuclear interactions between YAP1, ß-catenin, and the SS18-SSX fusion protein, the latter being an integral part of the BAF complex. Disruption of BAF complex assembly affected the coregulation of YAP1 and ß-catenin, indicating that this chromatin remodeling complex plays a crucial role for interdependent YAP1 and ß-catenin activation in synovial sarcoma cells. IMPLICATIONS: This study provides deeper insights into synovial sarcoma tumor biology demonstrating a mutual dependence between YAP1/TAZ and ß-catenin transcriptional activity and a complex interplay with the SS18-SSX fusion protein within the BAF complex.

Genetic susceptibility in children, adolescents, and young adults diagnosed with soft-tissue sarcomas.

Soft tissue sarcomas (STS) may arise as a consequence of germline variants in cancer predisposition genes (CPGs). We believe that elucidating germline sarcoma predisposition is critical for understanding disease biology and therapeutic requirements. Participation in surveillance programs may allow for early tumor detection, early initiation of therapy and, ultimately, better outcomes. Among children, adolescents, and adults diagnosed with soft-tissue sarcomas and examined as part of published germline sequencing studies, pathogenic/likely pathogenic (P/LP) variants in CPGs were reported in 7-33% of patients. P/LP germline variants were detected most frequently in TP53, NF1 and BRCA1/2. In this review, we describe reported associations between soft tissue sarcomas and germline variants in CPGs, with mentioning of locally aggressive and benign soft tissue tumors that have important associations with cancer predisposition syndromes. We also discuss recommendations for diagnostic germline genetic testing. Testing for sarcoma-predisposing germline variants should be considered as part of the routine clinical workup and care of any child, adolescent, or adult diagnosed with STS and take into account consequences for the whole family.

Efficacy of Multimodality Approach in Patients With Recurrent Head and Neck Squamous Cell Carcinoma.

BACKGROUND/AIM: Head and neck squamous cell carcinoma (HNSCC) is characterized by high relapse rates and low survival in comparison to other malignancies. PATIENTS AND METHODS: Fifty-two patients suffering from recurrent HNSCC were compared, analyzing the impact of different regimes, including surgery, radiotherapy (RT), chemotherapy and immunotherapy on progression-free survival (PFS), overall survival (OS), locoregional control (LRC), and adverse events. RESULTS: The standard RT technique was intensity-modulated radiotherapy (IMRT) in all patients. In the multivariate analysis, higher cumulative RT dose significantly influenced LRC whereas surgery and age significantly impacted PFS and OS. CONCLUSION: IMRT dose-escalation, as well as surgery, appear beneficial in the treatment of recurrent HNSCC. Moreover, nivolumab and platin-based therapy might be superior agents for systemic therapy in comparison to cetuximab.

Controversies in the management of patients with soft tissue sarcoma: Recommendations of the Conference on State of Science in Sarcoma 2022.

BACKGROUND: Owing to the rarity and heterogeneity in biology and presentation, there are multiple areas in the diagnosis, treatment and follow-up of soft tissue sarcoma (STS), with no, low-level or conflicting evidence. METHODS: During the first Consensus Conference on the State of Science in Sarcoma (CSSS), we used a modified Delphi process to identify areas of controversy in the field of sarcoma, to name topics with limited evidence-based data in which a scientific and knowledge gap may remain and a consensus statement will help to guide patient management. We determined scientific questions which need to be addressed in the future in order to generate evidence and to inform physicians and caregivers in daily clinical practice in order to improve the outcomes of patients with sarcoma. We conducted a vote on STS key questions and controversies prior to the CSSS meeting, which took place in May 2022. RESULTS: Sixty-two European sarcoma experts participated in the survey. Sixteen strong consensus (≥95%) items were identified by the experts, as well as 30 items with a ≥75% consensus on diagnostic and therapeutic questions. Ultimately, many controversy topics remained without consensus. CONCLUSIONS: In this manuscript, we summarise the voting results and the discussion during the CSSS meeting. Future scientific questions, priorities for clinical trials, registries, quality assurance, and action by stakeholders are proposed. Platforms and partnerships can support innovative approaches to improve management and clinical research in STS.

Recurrent EWSR1::COLCA2 Fusions Define a Novel Sarcoma With Spindle/Round Cell Morphology and Strong Predilection for the Sinonasal Tract.

The last 2 decades have attended a dynamic evolution in the nosology of poorly differentiated sinonasal tract malignancies, with several new molecularly defined entities having been described in addition to delineation of the genetic driver/s of some established older entities. These discoveries, however, mostly concerned epithelial-derived neoplasms (carcinomas). Adamantinoma-like Ewing sarcoma and biphenotypic sinonasal sarcoma are the major representatives of the newly defined mesenchymal categories. The colorectal cancer associated 2 (COLCA2) has been discovered recently as a colorectal cancer risk gene locus, but fusions involving this gene have not been well characterized. We, herein, describe clinicopathologic and molecular features of a novel sinonasal sarcoma characterized by undifferentiated spindle/round cell morphology and defined by recurrent EWSR1::COLCA2 fusions. All patients (n=5) were adults (3 female and 2 male) with a median age of 46 years (range, 23 to 60 y). The tumors originated in different subsites of the sinonasal tract with frequent multisite involvement. Original diagnoses were undifferentiated or unclassified round cell/spindle cell neoplasm/sarcoma (n=4) and neuroendocrine carcinoma (n=1). Surgery with or without adjuvant chemoradiation was the treatment in all cases. At the last follow-up, 1 patient developed multiple local recurrences over 21 years and another developed local recurrence and distant metastasis to bone 27 months after diagnosis. A third patient developed local recurrence 11 months later. Two patients were disease-free at 23, and 24 months. Histology showed nondescript highly cellular neoplasms with an admixture of spindled and round cells disposed into solid sheets and fascicles with brisk mitotic activity. Immunohistochemistry was negative for all lineage-specific markers with only limited focal membranous CD99 (4 of 5 cases) and weak pankeratin (1 of 5 cases) expression. Targeted RNA sequencing revealed an EWSR1::COLCA2 fusion, verified by EWSR1 fluorescence in situ hybridization, in all cases. This series identifies a novel member in the undifferentiated spindle/round cell sarcoma category with strong predilection for the sinonasal tract. None of >10,000 epithelial and mesenchymal neoplasms tested at the authors' centers during the same period showed this fusion, highlighting rarity of tumors carrying this gene fusion. Accordingly, molecular testing of unclassified sinonasal malignancies/sarcomas showing round and spindle cell morphology is recommended to enhance the identification and further characterization of this entity.

Comprehensive molecular profiling of sarcomas in adolescent and young adult patients: Results of the EORTC SPECTA-AYA international proof-of-concept study.

BACKGROUND: Adolescent and young adult (AYA) patients with cancer are poorly recruited to molecularly targeted trials and have not witnessed the advances in cancer treatment and survival seen in other age groups. We report here a pan-European proof-of-concept study to identify actionable alterations in some of the worst prognosis AYA cancers: bone and soft tissue sarcomas. DESIGN: Patients aged 12-29 years with newly diagnosed or recurrent, intermediate or high-grade bone and soft tissue sarcomas were recruited from six European countries. Pathological diagnoses were centrally reviewed. Formalin-fixed tissues were analysed by whole exome sequencing, methylation profiling and RNA sequencing and were discussed in a multidisciplinary, international molecular tumour board. RESULTS: Of 71 patients recruited, 48 (median 20 years, range 12-28) met eligibility criteria. Central pathological review confirmed, modified and re-classified the diagnosis in 41, 3, and 4 cases, respectively. Median turnaround time to discussion at molecular tumour board was 8.4 weeks. whole exome sequencing (n = 48), methylation profiling (n = 44, 85%) and RNA sequencing (n = 24, 50%) led to therapeutic recommendations for 81% patients, including 4 with germ line alterations. The most common were for agents targeted towards tyrosine kinases (n = 20 recommendations), DNA repair (n = 18) and the PI3K/mTOR/AKT pathway (n = 15). Recommendations were generally based on weak evidence such as activity in a different tumour type (n = 68, 61%), reflecting the dearth of relevant molecular clinical trial data in the same tumour type. CONCLUSIONS: We demonstrate here that comprehensive molecular profiling of AYA patients' samples is feasible and deliverable in a European programme.