Tumor-intrinsic and Cancer-associated Fibroblast Subtypes Independently Predict Outcomes in Pancreatic Cancer.

OBJECTIVE: To assess the utility of tumor-intrinsic and cancer-associated fibroblast (CAF) subtypes of pancreatic ductal adenocarcinoma (PDAC) in predicting response to neoadjuvant therapy (NAT) and overall survival. BACKGROUND: PDAC remains a deadly disease with limited treatment options, and both the tumor as well as the microenvironment play an important role in pathogenesis. Gene expression-based tumor-intrinsic subtypes (classical and basal-like) have been shown to predict outcomes, but tumor microenvironment subtypes are still evolving. METHODS: RNA-sequencing was performed on 114 deidentified resected PDAC tumors. Clinical data were collected by retrospective chart review. Single sample classifiers (SSCs) were used to determine classical and basal-like subtypes as well as tumor-permissive permCAF and tumor-restraining restCAF subtypes. Survival was analyzed using log-rank test. RESULTS: Patients who received NAT had an increase in overall survival (OS), with median survival of 27.9 months compared to 20.1 months for those who did not receive NAT, but the difference did not reach statistical significance (HR 0.64, P=0.076). Either tumor-intrinsic or CAF subtypes alone were associated with OS regardless of NAT or no NAT, and patients with classical or restCAF subtype had the best outcomes. When evaluated together, patients with classical-restCAF subtype had the best OS and basal-permCAF the worst OS (P<0.0001). NAT patients with classical-restCAF subtype demonstrated the longest OS compared to the other groups (P=0.00041). CONCLUSIONS: CAF subtypes have an additive effect over tumor-intrinsic subtypes in predicting survival with or without neoadjuvant FOLFIRINOX in PDAC. Molecular subtyping of both tumor and CAF compartments of PDAC may be important steps in selecting first-line systemic therapy.

Myofibroblastic cancer-associated fibroblast subtype heterogeneity in pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) has a fibrotic stroma that has both tumor-promoting and tumor-restraining properties. Different types of cancer-associated fibroblasts (CAFs) have been described. Here, we investigated whether CAFs within the same subtype exhibit heterogeneous functions. METHODS: We evaluated the gene and protein expression differences in two myofibroblastic CAF (myCAF) lines using single-cell and bulk RNA-sequencing. We utilized proliferation and migration assays to determine the effect of different CAF lines on a tumor cell line. RESULTS: We found that myCAF lines express an activated stroma subtype gene signature, which is associated with a shorter survival in patients. Although both myCAF lines expressed α-smooth muscle actin (α-SMA), platelet-derived growth factor-α (PDGFR-α), fibroblast-activated protein (FAP), and vimentin, we observed heterogeneity between the two lines. Similarly, despite being consistent with myCAF gene expression overall, heterogeneity within specific genes was observed. We found that these differences extended to the functional level where the two myCAF lines had different effects on the same tumor cell line. The myCAF216 line, which had slightly increased inflammatory CAF-like gene expression and higher protein expression of α-SMA, PDGFR-α, and FAP was found to restrain migration of tumor cells. CONCLUSIONS: We found that two myCAF lines with globally similar expression characteristics had different effects on the same tumor cell line, one promoting and the other restraining migration. Our study highlights that there may be unappreciated heterogeneity within CAF subtypes. Further investigation and attention to specific genes or proteins that may drive this heterogeneity will be important.

Determination of permissive and restraining cancer-associated fibroblast (DeCAF) subtypes.

Cancer-associated fibroblast (CAF) subpopulations in pancreatic ductal adenocarcinoma (PDAC) have been identified using single-cell RNA sequencing (scRNAseq) with divergent characteristics, but their clinical relevance remains unclear. We translate scRNAseq-derived CAF cell-subpopulation-specific marker genes to bulk RNAseq data, and develop a single- sample classifier, DeCAF, for the classification of clinically rest raining and perm issive CAF subtypes. We validate DeCAF in 19 independent bulk transcriptomic datasets across four tumor types (PDAC, mesothelioma, bladder and renal cell carcinoma). DeCAF subtypes have distinct histology features, immune landscapes, and are prognostic and predict response to therapy across cancer types. We demonstrate that DeCAF is clinically replicable and robust for the classification of CAF subtypes in patients for multiple tumor types, providing a better framework for the future development and translation of therapies against permissive CAF subtypes and preservation of restraining CAF subtypes. Significance: We introduce a replicable and robust classifier, DeCAF, that delineates the significance of the role of permissive and restraining CAF subtypes in cancer patients. DeCAF is clinically tractable, prognostic and predictive of treatment response in multiple cancer types and lays the translational groundwork for the preclinical and clinical development of CAF subtype specific therapies.

Pathology and Molecular Characteristics of Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. However, it should be kept in mind that there are other pancreatic cancers that are classified by their cellular lineage: acinar cell carcinomas (acinar differentiation), neuroendocrine neoplasms (arising from the islets), solid-pseudopapillary neoplasms (showing no discernible cell lineage), and pancreatoblastomas (characterized by multiphenotypic differentiation, including acinar endocrine and ductal). This article focuses on the molecular and pathology alterations in PDAC.

The PDAC Extracellular Matrix: A Review of the ECM Protein Composition, Tumor Cell Interaction, and Therapeutic Strategies.

Pancreatic ductal adenocarcinoma (PDAC) is notorious for a dense fibrotic stroma that is interlaced with a collagen-based extracellular matrix (ECM) that plays an important role in tumor biology. Traditionally thought to only provide a physical barrier from host responses and systemic chemotherapy, new studies have demonstrated that the ECM maintains biomechanical and biochemical properties of the tumor microenvironment (TME) and restrains tumor growth. Recent studies have shown that the ECM augments tumor stiffness, interstitial fluid pressure, cell-to-cell junctions, and microvascularity using a mix of biomechanical and biochemical signals to influence tumor fate for better or worse. In addition, PDAC tumors have been shown to use ECM-derived peptide fragments as a nutrient source in nutrient-poor conditions. While collagens are the most abundant proteins found in the ECM, several studies have identified growth factors, integrins, glycoproteins, and proteoglycans in the ECM. This review focuses on the dichotomous nature of the PDAC ECM, the types of collagens and other proteins found in the ECM, and therapeutic strategies targeting the PDAC ECM.

Accuracy of the ACS NSQIP Online Risk Calculator Depends on How You Look at It: Results from the United States Gastric Cancer Collaborative.

The objective of this study is to assess the accuracy of the American College of Surgeons National Surgical Quality Improvement Program online risk calculator for estimating risk after operation for gastric cancer using the United States Gastric Cancer Collaborative. Nine hundred and sixty-five patients who underwent resection of gastric adenocarcinoma between January 2000 and December 2012 at seven academic medical centers were included. Actual complication rates and outcomes for patients were compared. Most of the patients underwent total gastrectomy with Roux-en-Y reconstruction (404, 41.9%) and partial gastrectomy with gastrojejunostomy (239, 24.8%) or Roux-en-Y reconstruction (284, 29.4%). The C-statistic was highest for venous thromboembolism (0.690) and lowest for renal failure at (0.540). All C-statistics were less than 0.7. Brier scores ranged from 0.010 for venous thromboembolism to 0.238 for any complication. General estimates of risk for the cohort were variable in terms of accuracy. Improving the ability of surgeons to estimate preoperative risk for patients is critically important so that efforts at risk reduction can be personalized to each patient. The American College of Surgeons National Surgical Quality Improvement Program risk calculator is a rapid and easy-to-use tool and validation of the calculator is important as its use becomes more common.

Interval Magnetic Resonance Imaging: an Alternative to Guidelines for Indeterminate Nodules Discovered in the Cirrhotic Liver.

BACKGROUND: Current guidelines for the management of indeterminate nodules discovered on surveillance imaging recommend alternate imaging modality or biopsy. This study evaluates the use of short interval MRI rather than immediate CT or biopsy. METHOD: This retrospective cohort study examines outcomes of 111 patients with indeterminate nodules reviewed by a single institution's Liver Tumor Board 2011-2016. Analysis was focused on outcomes stratified by management decision. RESULTS: The tumor board recommended biopsy or immediate repeat CT imaging in 13 (12%), 3-month interval MRI in 64 (58%) and 6-month interval MRI for 34 (30%) patients. Twenty-eight (29%) patients in the interval MRI subgroups were diagnosed with hepatocellular carcinoma (HCC) during the period of follow-up, and 21 (75%) of these were located within the original indeterminate nodule. The median time to diagnosis was 6.5 months. Twenty-three (82%) were eligible for potentially curative therapy at the time of HCC diagnosis. Delay in HCC diagnosis was not the reason for inability to provide potentially curative therapy in any patient. CONCLUSION: This study supports the judicious use of interval MRI at 3 or 6 months in patients with liver cirrhosis and an indeterminate liver nodule rather than immediate CT scan or biopsy.