Tumors Of Origin Research Articles

Establishment of advanced tumor organoids with emerging innovative technologies

Tumor organoids have emerged as a crucial preclinical model for multiple cancer research. Their high establishment rates, stability, and ability to replicate key biological features of original tumor cells in vivo render them invaluable for exploring tumor molecular mechanisms, discovering potential anti-tumor drugs, and predicting clinical drug efficacy. Here, we review the establishment of tumor organoid models and provide an extensive overview of organoid culturing strategies. We also emphasize the significance of integrating cellular components of the tumor microenvironment and physicochemical factors in the organoid culturing system, highlighting the importance of artificial intelligence technology in advancing organoid construction. Moreover, we summarize recent advancements in utilizing organoid systems for novel anti-cancer drug screening and discuss promising trends for enhancing advanced organoids in next-generation disease modeling.

Immunohistochemical expression of SATB2 and PAX8 in differentiating primary from metastatic ovarian mucinous neoplasms.

Accurate stratification of an ovarian mucinous neoplasm as primary or secondary is always challenging as they show overlapping histomorphological and immunohistochemical features. Immunohistochemical staining for SATB2 and PAX8 was performed on 80 cases of mucinous ovarian neoplasms subdivided into 53 primary [25 primary ovarian mucinous carcinomas (POMCs) and 28 mucinous borderline tumors (MBTs)] and 27 secondary (12 of colonic origin, 7 of appendiceal origin, and 8 of gastric origin). Expression was correlated with different clinicopathologic parameters. PAX8-positive immunostaining was detected in 38 out of 53 cases (71.69%) of primary ovarian mucinous neoplasms (POMNs) with null positivity in the secondary ovarian mucinous tumors (0/27). SATB2-positive expression was detected in 16 out of 27 cases (59.26%) of the secondary ovarian mucinous tumors. None of the studied POMNs showed any positive immunostaining for SATB2 (0/53). A profile of SATB2-/PAX8+ and SATB2+/PAX8- can be used to differentiate POMNCs from secondary ovarian mucinous tumors of GI origin, respectively, with 100% specificity. PAX8 expression is associated with some clinicopathologic parameters providing the basis for the possible usage of PAX8 as prognostic marker.

Metastatic GIST with a TWIST of RCC: A case report

Gastrointestinal Stromal Tumors (GIST) is a tumor of mesenchymal origin in the digestive tract, arising from Interstitial cells of Cajal. Majorly, they are an incidental finding in people of older age group (>60 years) with very rare bone metastasis. Our aim is to understand the role of genetic mutations in metastasis of GIST and coexistence of other malignancy in the same patient. We present an unusual case of a 75-year-old male with jejunal GIST, managed with resection of the tumor and imatinib, who 15 years later presented with subsequent liver, rare femoral head metastases and coexisting Renal Cell Carcinoma in left kidney. GIST cases can be associated with different syndromes and malignancies. This necessitates additional work up and long term follow up.

Composite hemangioendothelioma of breast: A case report with review of literature

Composite hemangioendothelioma (CHE) is an intermediate grade neoplastic tumor of vascular origin. It consists of a varied mixture of benign, intermediate and malignantvascular components. Only few cases of CHE occurring in different soft tissue areas of the body and rarely in internal organs have been reported in literature till now. We report a case of CHE presenting as lump in the breast in a 42 year old female. A review of literature is also presented to create awareness of this entity which can be misleading in breast where angiosarcoma is also known to occur.

TOTEM: a multi-cancer detection and localization approach using circulating tumor DNA methylation markers

BackgroundDetection of cancer and identification of tumor origin at an early stage improve the survival and prognosis of patients. Herein, we proposed a plasma cfDNA-based approach called TOTEM to detect and trace the cancer signal origin (CSO) through methylation markers.MethodsWe performed enzymatic conversion-based targeted methylation sequencing on plasma cfDNA samples collected from a clinical cohort of 500 healthy controls and 733 cancer patients with seven types of cancer (breast, colorectum, esophagus, stomach, liver, lung, and pancreas) and randomly divided these samples into a training cohort and a testing cohort. An independent validation cohort of 143 healthy controls, 79 liver cancer patients and 100 stomach cancer patients were recruited to validate the generalizability of our approach.ResultsA total of 57 multi-cancer diagnostic markers and 873 CSO markers were selected for model development. The binary diagnostic model achieved an area under the curve (AUC) of 0.907, 0.908 and 0.868 in the training, testing and independent validation cohorts, respectively. With a training specificity of 98%, the specificities in the testing and independent validation cohorts were 100% and 98.6%, respectively. Overall sensitivity across all cancer stages was 65.5%, 67.3% and 55.9% in the training, testing and independent validation cohorts, respectively. Early-stage (I and II) sensitivity was 50.3% and 45.7% in the training and testing cohorts, respectively. For cancer patients correctly identified by the binary classifier, the top 1 and top 2 CSO accuracies were 77.7% and 86.5% in the testing cohort (n = 148) and 76.0% and 84.0% in the independent validation cohort (n = 100). Notably, performance was maintained with only 21 diagnostic and 214 CSO markers, achieving a training AUC of 0.865, a testing AUC of 0.866, and an integrated top 2 accuracy of 83.1% in the testing cohort.ConclusionsTOTEM demonstrates promising potential for accurate multi-cancer detection and localization by profiling plasma methylation markers. The real-world clinical performance of our approach needs to be investigated in a much larger prospective cohort.

Clinical features and prognosis of conjunctival melanoma in Japanese patients.

To evaluate the clinical features and prognosis of conjunctival melanoma in Japanese patients. Retrospective observational case series. Twenty patients (8 men and 12 women) diagnosed with conjunctival melanoma at a singlehospital between 2003 and 2017 were analyzed. Data on clinical presentation, sex, age, the affected eye, tumor location, tumor origin, tumor stage according to the American Joint Committee on Cancer staging system (eighth edition), treatment, outcomes, local recurrence, metastasis, and survival were extracted from the patients' medical records and reviewed. The mean age at diagnosis was 64.2 ± 14.8 years. Tumor locations at the first examination included the bulbar conjunctiva (n = 19), plica (n = 13), and fornix (n = 12). The tumor stage was T1 in 5 cases (25%), T2 in 12 cases (60%), T3 in 3 cases (15%), and T4 in none. The mean follow-up duration was 91.7 ± 46.0 months. The local recurrence rates at 1, 5, and 10 years were 5.0%, 18.8%, and 31.5%, respectively, whilst the metastasis rates were 5.0%, 25.6%, and 32.4%, respectively. Four of the 6 patients who experienced metastasis died; duration from metastasis to death was 17.5 months (range, 7-25). The 5-year survival rate for conjunctival melanoma was 78.8%. Tumor thickness was significantly associated with survival duration on univariate Cox regression analyses. The mortality rate for conjunctival melanoma in the Japanese population was lower and higher than that reported in the Chinese and United States populations, respectively. Tumor thickness was a prognostic factor for survival in patients with conjunctival melanoma.

In vivo mouse models for adult brain tumors: Exploring tumorigenesis and advancing immunotherapy development.

Brain tumors, particularly glioblastoma (GBM), are devastating and challenging to treat, with a low 5-year survival rate of only 6.6%. Mouse models are established to understand tumorigenesis and develop new therapeutic strategies. Large-scale genomic studies have facilitated the identification of genetic alterations driving human brain tumor development and progression. Genetically engineered mouse models (GEMMs) with clinically relevant genetic alterations are widely used to investigate tumor origin. Additionally, syngeneic implantation models, utilizing cell lines derived from GEMMs or other sources, are popular for their consistent and relatively short latency period, addressing various brain cancer research questions. In recent years, the success of immunotherapy in specific cancer types has led to a surge in cancer immunology-related research which specifically necessitates the utilization of immunocompetent mouse models. In this review, we provide a comprehensive summary of GEMMs and syngeneic mouse models for adult brain tumors, emphasizing key features such as model origin, genetic alteration background, oncogenic mechanisms, and immune-related characteristics. Our review serves as a valuable resource for the brain tumor research community, aiding in the selection of appropriate models to study cancer immunology.

Gemcitabine as chemotherapy of head and neck cancer in Fanconi anemia patients

Fanconi anemia (FA) is a rare hereditary disease resulting from an inactivating mutation in the FA/BRCA pathway, critical for the effective repair of DNA interstrand crosslinks (ICLs). The disease is characterized by congenital abnormalities, progressing bone marrow failure, and an increased risk of developing malignancies early in life, in particular head and neck squamous cell carcinoma (HNSCC). While ICL-inducing cisplatin combined with radiotherapy is a mainstay of HNSCC treatment, cisplatin is contra-indicated for FA-HNSCC patients. This dilemma necessitates the identification of novel treatment modalities tolerated by FA-HNSCC patients. To identify druggable targets, an siRNA-based genetic screen was previously performed in HNSCC-derived cell lines from FA and non-FA tumor origin. Here, we report that the Ribonucleotide Reductase (RNR) complex, consisting of the RRM1 and RRM2 subunits, was identified as a therapeutic target for both, FA and non-FA HNSCC. While non-FA HNSCC cells responded differentially to RNR depletion, FA-HNSCC cells were consistently found hypersensitive. This insight was confirmed pharmacologically using 2′, 2′-difluoro 2′deoxycytidine (dFdC), also known as gemcitabine, a clinically used nucleotide analog that is a potent inhibitor of the RNR complex. Importantly, while cisplatin exposure displayed severe, long-lasting toxicity on the hematopoietic stem and progenitor compartments in Fancg−/− mice, gemcitabine was well tolerated and had only a mild, transient impact. Taken together, our data implicate that gemcitabine-based chemoradiotherapy could serve as an alternative HNSCC treatment in Fanconi patients, and deserves clinical testing.

Head and neck tumors detected in dogs and cats between 2011 and 2021: A retrospective study

The aim of this study is to determine and compare the distribution, localization, breed, age and gender incidences of head and neck region tumors by years, by evaluating the results of dog-cat biopsies and/or operation material brought to Ankara University, Faculty of Veterinary Medicine, Department of Pathology between the years 2011 and 2021. In the study, 244 (15.9%) of 1533 tumors diagnosed in dogs and cats between 2011 and 2021 belonged to the head and neck region, of which 159 were in dogs and 85 in cats. Dogs with tumors were generally more than 6 years old (n=108) and cats were mostly 1 year old and older (n=75). In the head and neck region tumors observed in dogs, malignant and benign tumors of epithelial origin were most common (n=81; 50.9%), with sebaceous tumors (n=22) being the most common, and mostly observed around the eyes (n=26), while malignant and benign tumors of mesenchymal origin were most commonly found in the mouth region. Among the tumors of this region, epithelial tumors were mostly encountered in cats (n=39, 45.8%), and 51.2% of the epithelial tumors were squamous cell cancer (n=20), with epithelial tumors being the most common in the mouth (n=12) and nose (n=9). As a result, epithelial malignant and benign tumors were mostly seen in the eyes, and mesenchymal malignant and benign tumors were detected in the mouth. Among tumor types, papilloma in benign tumors and squamous cell carcinoma in malignant tumors were noted.

Metastatic onset of prostate carcinoma: A clinical and pathological challenge.

Prostate cancer is the second most common cancer, following lung cancer, and the fifth leading cause of cancer death in men worldwide. The onset of the disease, characterized by symptoms or changes caused by distant metastases, is rare and poses a challenge for clinicians and pathologists. We aimed to present a series of prostate carcinoma (PC) with unusual, histologically confirmed distant metastases (pM1) at the time of diagnosis, which raised suspicions of other types or origins of the primary tumor. Patients diagnosed with PC and distant metastases within a five-year timeframe (2017-2022) were extracted from the hospital database. The following data were collected: patient's age, imaging data, serum PSA level, and histopathological evaluation results. Patients with unusual distant metastases were selected and analyzed. We identified 10 patients in whom the diagnosis of PC was established following histopathological examination of tissue taken from distant metastatic sites (pM1). In three patients, the location of distant metastases was unusual: retroperitoneal, cranial/dural/epicranial and supradiaphragmatic lymph nodes which posed diagnostic challenges. Establishing the prostate origin of the tumor relied on immunohistochemical (IHC) investigation guided by clinical-imaging information. A metastasis of PC may rarely present as a cranial/dural tumor, retroperitoneal, or supradiaphragmatic lymphadenopathies in a man over the age of 50, but it should be taken into consideration. In the absence of correlated clinical, imaging, and histopathological/IHC data, diagnosing distant metastasis from PC is difficult, especially considering its potentially confusing IHC profile.

Diagnosis of metastatic melanoma by fine-needle aspiration biopsy and primary melanoma by using the skin and mucousa imprints

BACKGROUND: Determination of the cytogenetic origin and morphological type of metastatic or primary tumor determines the prescription of therapy and affects the efficiency of patient’s treatment. Currently, a number of publications evaluate the potential of cytological diagnostics of melanoma. AIM: To evaluate the significance of diagnosing metastatic melanoma by fine-needle aspiration biopsy and primary melanoma by using the skin and mucosa imprints. METHODS: In a retrospective study, a comparative analysis of cytological melanoma samples, in comparison with clinical and anamnestic information and the results of histological, immunohistochemical, and molecular genetic studies, was carried out. Information about 109 patients from the cancer registry of the Altai Regional Oncology Dispensary (Barnaul, Russia) for 2022 was used in the study. Traditional and liquid-based methods for preparing samples were used. The samples were stained using Pappenheim and Papanicolaou methods. In some observations, cytological material was used for molecular genetic studies. Using the cancer registry data of the dispensary, the results of histological and of molecular genetic studies, and a final conclusion was given about each patient. RESULTS: Fine-needle aspiration biopsy was carried out in 80 patients. Tumor smears were obtained from 29 patients. The cytological diagnose “melanoma” was consistent with the data of histological and immunohistochemical studies (p 0.001) for all 109 patients. Melanoma was diagnosed for the first time in 66 (60.5%) patients. In other cases, the process of progression was noted within the period from one year to 20 years. Epidermal melanoma was noted in 101 (92.7%) cases, including 9 patients with acral melanoma, and 2 cases with localization on the vulva. Melanomas of mucosa were found in 5 cases (4.5%): in the rectum and anal canal, vagina, and in 2 cases on the hard palate. Non-epidermal (uveal) melanomas metastases were diagnosed in liver by fine-needle aspiration biopsy in 3 patients (2.8%). Based on the cellular composition, epithelioid cell melanoma was determined in 81 (74.3%) patients, mixed cell in 14 (12.8%) cases, spindle cell in 9 (8.2%), pigmentless in 2 (1.8%) cases and nevoid melanoma in 1 (0.9%) case. The mutation status was determined in 96 patients (88.1%). Of these, in 8 patients it was determined using cytological material. In epidermal melanomas, mutations in codon 600 of exon 15 of the BRAF gene were found in 43 (44.8%) patients, including 2 cases of acral melanoma. Mutations V600K, V600E/Ec were found in one patient each. In mucousal melanomas: Q61R mutation was found in exon 3 of the NRAS gene (vaginal melanoma), G12C mutation was identified in exon 2 of the NRAS gene (anal canal melanoma). In uveal melanomas, the assessed mutations were absent (it is necessary to determine mutation is GNAQ11 and BAP1 genes). CONCLUSION: Cytological diagnosis of melanoma by fine-needle aspiration biopsies and imprints from the tumor mass is a highly informative method that allows diagnosing melanoma and verifying the tumor subtype. The obtained results indicate tumor heterogeneity and differences in mutational status depending on the location of melanomas. The molecular classification of melanoma is important when choosing individualized therapy.

Multimodal diagnostic strategies and precision medicine in mucinous ovarian carcinoma: a comprehensive approach.

Mucinous ovarian carcinoma (MOC) represents a distinct entity within ovarian malignancies, characterized by diagnostic challenges due to its rarity and the potential overlap with other tumor types. The determination of tumor origin is important for precise postsurgical treatment. This article highlights the accurate diagnosis and management of MOC, including the use of imaging modalities, serological tumor markers, immunohistochemistry, and genomic analyses. Transabdominal and transvaginal ultrasonography, complemented by MRI and CT, plays a pivotal role in differentiating MOC from other mucinous tumors and in surgical planning, particularly for fertility preservation. Serological markers like CA19-9, CA-125, and CEA, though not definitive, provide valuable preoperative insights. Immunohistochemistry aids in distinguishing primary MOC from metastatic mucinous carcinomas, while genomic profiling offers the potential for precision medicine through the identification of specific molecular signatures and treatment susceptibilities. Despite advancements in diagnostic techniques, no single method conclusively differentiates between primary and metastatic tumors intraoperatively. The paper reviews the origins, diagnosis, and differential diagnosis of primary mucinous ovarian carcinoma highlights the need for a multimodal diagnostic approach and advocates for the inclusion of MOC patients in clinical trials for personalized therapies, recognizing the heterogeneity of the disease at the molecular level.

Pan-cancer Analysis Reveals m6A Variation and Cell-specific Regulatory Network in Different Cancer Types.

As the most abundant messenger RNA (mRNA) modification in mRNA, N 6-methyladenosine (m6A) plays a crucial role in RNA fate, impacting cellular and physiological processes in various tumor types. However, our understanding of the function and role of the m6A methylome in tumor heterogeneity remains limited. Herein, we collected and analyzed m6A methylomes across nine human tissues from 97 m6A sequencing (m6A-seq) and RNA sequencing samples. Our findings demonstrate that m6A exhibits different heterogeneity in most tumor tissues compared to normal tissues, which contributes to the diverse clinical outcomes in different cancer types. We also found that the cancer type-specific m6A level regulated the expression of different cancer-related genes in distinct cancer types. Utilizing a novel and reliable method called "m6A-express", we predicted m6A-regulated genes and revealed that cancer type-specific m6A-regulated genes contributed to the prognosis, tumor origin, and infiltration level of immune cells in diverse patient populations. Furthermore, we identified cell-specific m6A regulators that regulate cancer-specific m6A and constructed a regulatory network. Experimental validation was performed, confirming that the cell-specific m6A regulator CAPRIN1 controls the m6A level of TP53. Overall, our work reveals the clinical relevance of m6A in various tumor tissues and explains how such heterogeneity is established. These results further suggest the potential of m6A for cancer precision medicine for patients with different cancer types.

Giant vulvar lipoma. Case report

Vulvar lipomas (VL) are rare, benign tumors of mesenchymal origin. Less than one hundred observations of VL have been published in the literature. The authors describe a clinical observation of a giant VL and also provide a review of the literature on this pathology.

Concomitant decrease of E- and A-FABP expression predicts worse survival in urothelial bladder cancer patients

Non-muscle invasive bladder cancers (NMIBC) pTa-pT1 are depicted by a high risk of recurrence and/or progression with an unpredictable clinical evolution. Our aim was to identify, from the original resection specimen, tumors that will progress to better manage patients. We previously showed that A-FABP (Adipocyte- Fatty Acid Binding Protein) loss predicted NMIBC progression. Here we determined by immunohistochemistry the prognostic value of E-FABP (Epidermal-Fatty Acid Binding Protein) expression in 210 tumors (80 pTa, 75 pT1, 55 pT2-T4). Thus, E-FABP low expression was correlated with a high grade/stage, the presence of metastatic lymph nodes, and visceral metastases (p < 0.001). Unlike A-FABP in NMIBC, E-FABP low expression was not associated with RFS or PFS in Kaplan–Meier analysis. But patients of the overall cohort with a high E-FABP expression had a longer mOS (53.8 months vs. 29.3 months, p = 0.029). The immunohistochemical analysis on the same NMIBC tissue sections revealed that when A-FABP is absent, a high E-FABP expression is detected. E-FABP could compensate A-FABP loss. Interestingly, patients, whose original tumor presents both low E-FABP and negative A-FABP, had the worse survival, those maintaining the expression of both markers had better survival. To conclude, the combined evaluation of A- and E-FABP expression allowed to stratify patients with urothelial carcinoma for optimizing treatment and follow-up.

Synergic activity of FGFR2 and MEK inhibitors in the treatment of FGFR2-amplified cancers of unknown primary

Patients with cancer of unknown primary (CUP) carry the double burden of an aggressive disease and reduced access to therapies. Experimental models are pivotal for CUP biology investigation and drug testing. We derived two CUP cell lines (CUP#55 and #96), and corresponding patient-derived xenografts (PDXs), from ascites tumor cells. CUP cell lines and PDXs underwent histological, immune-phenotypical, molecular, and genomic characterization confirming the features of the original tumor. The tissue-of-origin prediction was obtained from the tumor microRNA expression profile and confirmed by single-cell transcriptomics. Genomic testing and FISH analysis identified FGFR2 gene amplification in both models, in the form of homogenously staining region (HSR) in CUP#55 and double minutes in CUP#96. FGFR2 was recognized as the main oncogenic driver and therapeutic target. FGFR2-targeting drug BGJ-398 (infigratinib) in combination with the MEK inhibitor trametinib proved to be synergic and exceptionally active, both in vitro and in vivo. The effects of the combined treatment by single-cell gene expression analysis revealed a remarkable plasticity of tumor cells and the greater sensitivity of cells with epithelial phenotype. This study brings personalized therapy closer to CUP patients and provides the rationale for FGFR2 and MEK targeting in metastatic tumors with FGFR2 pathway activation.

Identification of placenta-specific protein 1 (PLAC-1) expression on human PC-3 cell line-derived prostate cancer stem cells compared to the tumor parental cells

Placenta-specific protein 1 (PLAC-1) is a gene primarily expressed in the placenta and the testis. Interestingly, it is also found to be expressed in many solid tumors, and it is involved in malignant cell features. However, no evidence has been reported regarding the relationship between PLAC-1 and cancer stem cells (CSCs). In the current research, we explored the expression of the PLAC-1 molecule in prostate cancer stem cells (PCSCs) derived from the human PC-3 cell line. The enrichment of PCSCs was achieved using a three-dimensional cell culture technique known as the sphere-formation assay. To confirm the identity of PCSCs, we examined the expression of genes associated with stemness and pluripotency, such as SOX2, OCT4, Nanog, C-Myc, and KLF-4, as well as stem cell differentiation molecules like CD44 and CD133. These evaluations were conducted in both the PCSCs and the original tumor cells (parental cells) using real-time PCR and flow cytometry. Subsequently, we assessed the expression of the PLAC-1 molecule in both enriched cells and parental tumor cells at the gene and protein levels using the same techniques. The tumor cells from the PC-3 cell line formed spheroids with CSC characteristics in a non-adherent medium. The expression of SOX2, OCT4, Nanog, and C-Myc genes (p < 0.01), and the molecules CD44 and CD133 (p < 0.05) were significantly elevated in PCSCs compared to the parental cells. The expression of the PLAC-1 molecule in PCSCs showed a significant increase compared to the parental cells at both gene (p < 0.01) and protein (p < 0.001) levels. In conclusion, it was indicated for the first time that PLAC-1 is up-regulated in PCSCs derived from human PC-3 cell line. This study may propose PLAC-1 as a potential target in targeted therapies, which should be confirmed through further studies.

Solitary intraosseous neurofibroma of the oral cavity: rare localization in the maxilla

BackgroundNeurofibroma is a common benign tumor of neuronal origin that can occur as a solitary tumor or as a component of the generalized syndrome of neurofibromatosis. Neurofibromas are primarily located in the subcutaneous soft tissues and commonly involve extra-oral sites. Solitary intraosseous neurofibromas of the oral cavity are infrequent, with occurrences in the maxilla being exceedingly rare.Case presentationA 22-year-old male patient presented with an asymptomatic mass in the maxilla. Cone-beam computed tomography revealed a round, well-outlined, radiolucent lesion with expansive growth. The neoplasm with the complete capsule was completely removed and confirmed as a neurofibroma based on histopathological and immunohistochemical findings. The reported cases of solitary intraosseous neurofibromas located in the maxilla published in the English literature were compiled to assist in the diagnosis of solitary intraosseous neurofibromas of the maxilla. Nine months after the surgery, there were no signs of tumor recurrence or malignant transformation.ConclusionsThis report emphasizes that rare locations of neurofibromas, such as solitary intraosseous neurofibromas in the maxilla, typically demonstrate nonspecific clinical and radiological features. Clinicians should consider solitary intraosseous neurofibromas as possible differential diagnoses and recognize the histopathological and immunohistochemical features to confirm the correct diagnosis. A longer follow-up period is required because of the potential for local recurrence and malignant transformation of these tumors.

Surgical management of anterior mediastinal tumors of thyroid origin: a comprehensive analysis of approaches, techniques, and outcomes

BackgroundThis manuscript aims to describe the symptoms, demographics, surgical approaches and techniques, the volume of surgical interventions, histological results, intra- and postoperative complications, and postoperative results in patients with anterior mediastinal tumors of thyroid origin (AMTTO).MethodsTwenty patients with AMTTO were operated between 2017 and 2021. Fifteen were women and 5 were men. The mean age was 66.8 years.ResultsThe most common histology was nodular micro- and macrofollicular goiter (15/20, 75%). Kocher cervicotomy (65%) was the preferred approach. Total thyroidectomy was performed in 95% of patients. Intraoperative complications were identified in 25% (5/20), and in 2 patients a tracheostomy was required. Early postoperative complications were established in 65% and the most common was unilateral transient recurrent nerve paresis or paralysis and dysphonia (25%).ConclusionsCommonly resection of AMTTO is a challenge due to its complexities associated with high-risk cases, emphasizing the need for experienced centers in managing such cases.

STEM-07. CONSERVATION AND FAITHFUL REPRESENTATION OF CIRCULAR EXTRACHROMOSOMAL DNA IN ORTHOTOPIC PATIENT-DERIVED MEDULLOBLASTOMA XENOGRAFTS

Abstract BACKGROUND Extrachromosomal DNA (ecDNA) drives tumor heterogeneity and correlates with poor survival across various cancer types. Patient-derived xenograft (PDX) models facilitate preclinical drug testing in vivo, enabling tumor growth analysis and molecular tumor profiling. These models, combined with single-cell profiling, offer insights into intratumoral heterogeneity under therapeutic pressure and the emergence of drug resistance. We investigate the abundance and conservation of ecDNA in PDX models to assess the faithful representation of ecDNA compared to their corresponding primary tumors. METHODS Whole-genome sequencing (WGS) was applied to 27 medulloblastoma (MB) PDX models and their tumors of origin using Amplicon Architect. ecDNA frequency in these models was also compared to that in the MB patient population. Optical genome mapping enabled accurate and reliable ecDNA sequence reconstructions. Multiome single-cell RNA and ATAC-sequencing of a PDX tumor enabled analysis of ecDNA conservation and intratumoral heterogeneity compared to similar data previously obtained from the primary tumor. RESULTS ecDNA is largely conserved in PDX models, emphasizing their relevance as faithful models of the primary tumors. MB PDX models exhibit significant higher ecDNA frequency (16 out of 27 tumors) as compared to their frequency in the overall patient population (~18%), suggesting ecDNA as a driver for successful establishment of MB PDX models. Single-cell analysis revealed that ecDNA is omnipresent in almost all PDX tumor cells, contrasting with only ~9% of tumor cells in the primary tumor. CONCLUSIONS ecDNA analysis in medulloblastoma primary tumors and in PDX models revealed that ecDNA is preserved in PDX models. These findings emphasize the relevance of PDX models in preclinical in vivo studies aimed at analyzing the role of ecDNA under therapeutic pressure and for analyzing clonal selection along with molecular evolution of ecDNA during the development of therapeutic resistance.