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Abstract Numerous cell states are known to comprise the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME). However, the developmental stemness and co-occurrence of these cell states remain poorly defined. Here, we performed single-cell RNA sequencing (scRNA-seq) on a cohort of treatment-naive PDAC time-of-diagnosis endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) samples (n = 25). We then combined these samples with surgical resection (n = 6) and publicly available samples to increase statistical power (n = 80). Following annotation into 25 distinct cell states, cells were scored for developmental stemness, and a customized version of the Ecotyper tool was used to identify communities of co-occurring cell states in bulk RNA-seq samples (n = 268). We discovered a tumor microenvironmental community comprised of aggressive basal-like malignant cells, tumor-promoting SPP1+ macrophages, and myofibroblastic cancer-associated fibroblasts associated with especially poor prognosis. We also found a developmental stemness continuum with implications for survival that is present in both malignant cells and cancer-associated fibroblasts (CAFs). We further demonstrated that high-dimensional analyses predictive of survival are feasible using standard-of-care, time-of-diagnosis EUS-FNB specimens. In summary, we identified tumor microenvironmental and developmental stemness characteristics from a high-dimensional gene expression analysis of PDAC using human tissue specimens, including time-of-diagnosis EUS-FNB samples. These reveal new connections between tumor microenvironmental composition, CAF and malignant cell stemness, and patient survival that could lead to better upfront risk stratification and more personalized upfront clinical decision-making.

Tuberous Sclerosis 1/2 (TSC1/2) functions as a negative regulator of the mammalian target of rapamycin (mTOR) pathway, one of the key oncogenic pathways described in neuroendocrine neoplasm (NEN) carcinogenesis. While loss-of-function mutations in TSC1/2 lead to disinhibition of mTOR and uncontrolled cellular growth and proliferation, they concomitantly result in p53 sensitivity which manifests functionally as sensitivity to DNA damage. Here we report a case of a 57-year old male patient with a well-differentiated pancreatic NEN (PanNEN) who underwent neoadjuvant chemotherapy with capecitabine and temozolomide and achieved a near-complete pathologic response. The unusual response prompted further tumor characterization with next-generation sequencing which demonstrated a previously uncharacterized mutation in TSC2. We hypothesize that the TSC2 mutation may have contributed towards the exceptional response to the DNA damaging alkylating agent-based chemotherapy regimen. Furthermore, this case warrants the evaluation of alkylating agent-based chemotherapy regimens in NENs harboring mutations in mTOR pathway negative regulators such as TSC1/2.

To determine the safety, tolerability and maximum tolerated dose (MTD) of addition of erlotinib to bevacizumab and capecitabine-based definitive chemoradiation (CRT) in unresectable pancreatic cancer.Seventeen patients with CT-staged, biopsy-proven unresectable pancreatic cancer were enrolled between 3/2008 and 10/2010. Prior chemotherapy was permitted. Two patients each were enrolled at dose levels (DLs) 1-4 and 9 patients at DL 5. All patients received 50.4 Gy (GTV only) in 28 fractions with concurrent capecitabine, bevacizumab and erlotinib. Dose of each drug was escalated in 5 DLs using the continual reassessment method. Bevacizumab was escalated from 5mg/Kg q2weeks (DLs 1-4) to 10mg/Kg q2weeks (DL 5); daily erlotinib from 100mg/day (DLs 1-2) to 150 mg/Kg (DLs 3-5); and capecitabine from 400mg/m2 twice daily on days of radiation (DL 1) to 650mg/m2 (DLs 2-3) to 825 mg/m2 (DLs 4-5). Reassessment for potential resection was performed 6-8 weeks later.Sixteen patients received gemcitabine-based chemotherapy prior to CRT. With a median clinical follow-up of 10 months, no grade 3 toxicities were observed in DLs 1-4. Three (33%) patients at DL 5 developed a grade 3 acute toxicity (2 diarrhea, 1 rash). No grade 4 or 5 toxicities were seen. DL 4 was selected as the MTD; therefore, the recommended doses in combination with radiation are: bevacizumab, 5mg/Kg q2weeks; erlotinib, 150 mg/Kg daily; and capecitabine, 825mg/m2 BID. Median survival was 17.4 months. Of the five patients who underwent resection, 4 were originally deemed locally advanced and 1 was borderline resectable. Three patients had excellent pathological response (2 complete response and 20% viable tumor) at surgery, and the 2 patients with complete response are still alive at 61 and 67 months of follow up with no local or distant failures.This chemoradiation regimen at the recommended dose levels is safe and tolerable for patients with unresectable pancreatic cancer and merits further evaluation.

Expression of the cellular adhesion protein N-cadherin is a critical event during epithelial-mesenchymal transition (EMT). The SMAD4 protein has been identified as a mediator of transforming growth factor-β (TGF-β) superfamily signaling, which regulates EMT, but the mechanisms linking TGF-β signaling to N-cadherin expression remain unclear. When the TGF-β pathway is activated, SMAD proteins, including the common mediator SMAD4, are subsequently translocated into the nucleus, where they influence gene transcription via SMAD binding elements (SBEs). Here we describe a mechanism for control of CDH2, the gene encoding N-cadherin, through the canonical TGFβ-SMAD4 pathway. We first identified four previously undescribed SBEs within the CDH2 promoter. Using telomerase immortalized human pancreatic ductal epithelium, we found that TGF-β stimulation prompted specific SMAD4 binding to all four SBEs. Luciferase reporter and SMAD4-knockdown experiments demonstrated that specific SMAD4 binding to the SBE located at -3790 bp to -3795 bp within the promoter region of CDH2 was necessary for TGF-β-stimulated transcription. Expression of N-cadherin on the surface of epithelial cells facilitates motility and invasion, and we demonstrated that knockdown of SMAD4 causes decreased N-cadherin expression, which results in diminished migration and invasion of human pancreatic ductal epithelial cells. Similar reduction of cell motility was produced after CDH2 knockdown. Together, these findings suggest that SMAD4 is critical for the TGF-β-driven upregulation of N-cadherin and the resultant invasive phenotype of human pancreatic ductal epithelial cells during EMT.

We describe the use of an endoscopic modified Lothrop approach for clearance of an extensive sinonasal-type hemangiopericytoma of the nasal cavity and paranasal sinuses with bilateral frontal sinus involvement in a 44-year-old woman. The modified Lothrop approach is conventionally used to treat sinusitis, but with some slight modifications to the technique, it can also be used for tumor excision. [ABSTRACT FROM AUTHOR]