Sinonasal intestinal-type adenocarcinoma (ITAC) is strongly related to occupational exposure to wood and leather dust, however, little is known on the genetic alterations involved in tumor development and progression. The aim of this study was to identify tumorigenic signaling pathways affected by gene mutations and their relation to clinical features. We applied whole exome sequencing of 120 cancer-related genes in 50 ITACs and analyzed the signaling activity of four specific pathways frequently affected by mutations. Genes involved in DNA damage response showed somatic mutations in 30% of cases, including four tumors that also harbored germline mutations. Genes in Wnt, MAPK and PI3K pathways harbored mutations in 20%, 20% and 24% of cases, respectively. Mutations and copy number gains in receptor tyrosine kinases possibly affecting MAPK and PI3K pathways occurred in 44% of cases. Expression of key pathway proteins showed no correlation to mutations in these pathways, except for nuclear β-catenin and APC/CTNNB1 mutation. No specific gene mutation, mutated pathway, nor pathway activity level showed correlation to clinical data or survival. In addition, a similar mutational profile was observed among histological subtypes. The wide spectrum of gene mutations suggests that ITAC is a genetically heterogeneous without specific characterizing gene mutations.

Despite advances in surgery and radiotherapy, the overall prognosis of sinonasal intestinal-type adenocarcinoma (ITAC) is poor, and new treatment options are needed. Recent studies have indicated alterations in cellular signaling pathways that may serve as targets for modern inhibitors. Our aim was to evaluate the frequency of mTOR and ERK pathway upregulation in a retrospective series of 139 ITAC and to test the efficacy and mechanism of action of candidate targeted inhibitors in cell line ITAC-3. An immunohistochemical analysis on p-AKT, p-mTOR, p-S6, p-4E-BP1, and p-ERK indicated, respectively, a 68% and 57% mTOR and ERK pathway activation. In vitro studies using low doses of mTOR inhibitor everolimus and ERK inhibitor selumetinib showed significant growth inhibition as monotherapy and especially as combined therapy. This effect was accompanied by the downregulation of mTOR and ERK protein expression. Our data open a new and promising possibility for personalized treatment of ITAC patients.

Human Papillomavirus (HPV) related Multiphenotypic Sinonasal Carcinoma (HMSC) is a rare tumor with features of both atypical squamous cell and adenoid cystic carcinoma, making diagnosis challenging. Approximately 80% of HMSC cases carries HPV type 33 followed by type 35. We present a patient with HMSC. Pathological classification was aided by immunohistochemistry (IHC). The presence of HPV-DNA was tested using PCR and HPV E6/E7 expression by RNA in situ hybridization (RNA ISH). Whole exome sequencing (WES) was used to identify somatic gene mutations and copy number alterations. A 55-year-old male presented with an HMSC in the right nostril. Histological examination showed a solid basaloid subtype with mucinous spaces and ductal structures. IHC showed positive staining for SOX-10, SMA, p40, p63, PanCK, CK8 and MYB. Diffuse positive staining for p16 was observed and PCR and RNA ISH indicated the presence of HPV type 35. The patient was treated with endoscopic surgery and radiotherapy and is currently alive and recurrence-free after 16 months of follow-up. WES revealed 38 somatic sequence variants and several chromosomal regions with copy number alterations, including a copy number gain at 6q23 where MYB is located. EP300, ZNF22, ZNF609 and LRIG3 are some of the genes whose mutations were indicated as probably pathogenic. We did not find mutations predictive for drug response according to the ESMO Scale for Clinical Actionability of Molecular Targets database. This is the first report of WES analysis of an HMSC, in this case associated with HPV type 35. The detected mutation in EP300 and the overexpression of MYB may serve as molecular targets for personalized therapy.

Sinonasal teratocarcinosarcoma (TCS) is a rare tumor that displays a variable histology with admixtures of epithelial, mesenchymal, neuroendocrine and germ cell elements. Facing a very poor prognosis, patients with TCS are in need of new options for treatment. Recently identified recurrent mutations in SMARCA4 may serve as target for modern therapies with EZH1/2 and CDK4/6 inhibitors. Here, we present the first in vitro cell line TCS627, established from a previously untreated primary TCS originating in the ethmoid sinus with invasion into the brain. The cultured cells expressed immunohistochemical markers, indicating differentiation of epithelial, neuroepithelial, sarcomatous and teratomatous components. Whole-exome sequencing revealed 99 somatic mutations including SMARCA4, ARID2, TET2, CDKN2A, WNT7A, NOTCH3 and STAG2, all present both in the primary tumor and in the cell line. Focusing on mutated SMARCA4 as the therapeutic target, growth inhibition assays showed a strong response to the CDK4/6 inhibitor palbociclib, but much less to the EZH1/2 inhibitor valemetostat. In conclusion, cell line TCS627 carries both histologic and genetic features characteristic of TCS and is a valuable model for both basic research and preclinical testing of new therapeutic options for treatment of TCS patients.

Purpose Sinonasal undifferentiated carcinoma (SNUC), sinonasal neuroendocrine carcinoma (SNEC), and olfactory neuroblastoma (ONB) represent a heterogeneous group of high-grade sinonasal tumors with overlapping morphological and immunophenotypic features, making accurate classification challenging. Our aim was to apply genetic and immunohistochemical analyses to reclassify a cohort of cases and to compare their clinical features. Methods We analyzed 61 tumors originally diagnosed as ONB (n = 15), SNEC (n = 12), and SNUC (n = 34). Immunohistochemistry was performed for cytokeratin (CK), six neuroendocrine (NE) markers (synaptophysin, chromogranin A, CD56, INSM1, NeuroD1, ASCL1), p16, Ki67, SMARCB1, SMARCA4, and NUT. IDH2 R172 mutation status was assessed by Sanger sequencing and immunohistochemistry. Results were correlated with clinical and follow-up data. Results Reclassification was required in 22/61 cases (36%) and concerned one SMARCA4-deficient carcinoma, one SMARCB1-deficient carcinomas, one NUT carcinoma, 14 IDH2-mutated carcinomas, and five cases consistent with olfactory carcinoma (OC). A NE-high profile was identified in all reclassified tumour subtypes except SMARCB1-, SMARCA4-, and NUT-rearranged carcinomas, occurring in 8/9 (89%) ONB, 4/5 (80%) OC, 3/9 (33%) SNEC, 6/21 (29%) SNUC, and 5/14 (36%) IDH2-mutated carcinomas. IDH2-mutated carcinomas were found across all 3 diagnostic categories and were associated with significantly better 5-year disease-free survival (83% versus 31%, p = 0.027). ONB patients showed the most favorable outcome with 5-year overall survival of 86% versus 46% for combined SNEC and SNUC (p = 0.133). A tendency toward longer overall survival was also observed for CK-negative tumors (81% versus 42%, p = 0.051) and for NE-high tumors (73% versus 40%, p = 0.086).. No associations were found between Ki67 index and outcome. Conclusion High-grade sinonasal tumors with neuroectodermal differentiation show substantial histological and immunophenotypic overlap, and over one-third required reclassification when applying extended immunohistochemical and genetic profiling. Our findings emphasize the clinical relevance of refining tumor classification, particularly regarding IDH2 mutation status and CK/NE expression patterns, to improve prognostication and therapeutic decision-making.