Clinicopathological significance of SMAD4 loss in pancreatic ductal adenocarcinomas: a systematic review and meta-analysis

A Novel Diagnostic Model of Biomarkers in the Washing Fluid Obtained by EUS-FNA in Pancreatic Cancer

BACKGROUND AND AIMS

Currently, there are no biomarkers with high accuracy in the detection of pancreatic cancer. This article aims to evaluate the performance of a novel diagnostic model based on a combination of biomarkers in the washing fluid obtained by EUS-FNA with imaging examination in pancreatic cancer.

METHODS

This study included 59 patients with pancreatic lesions who underwent EUS-FNA and were categorized into malignant and benign groups on the basis of pathology diagnosis. The levels of CEA, CA19-9, CA125, CA724, CYFRA 21-1, IMP3, SMAD4, and S100P in EUS-FNA washing fluid were detected by ELISA. We attempted to construct a new diagnostic method by combining the above biomarkers with EUS, CT, MRI, and PET-CT.

RESULTS

CEA, CA19-9, CA724, CA125, and CYFRA 21-1 showed statistical significance in the diagnosis of pancreatic cancer (AUC > 0.7, p < 0.05). CA724 had a specificity of up to 100% in the group with positive EUS diagnosis. If at least two positive imaging results (EUS/CT/MRI/PET-CT) combined with at least one tumor marker (CEA/CA199/CA724) in series, the sensitivity was 88.57% and the specificity was 91.67%.

CONCLUSIONS

Combining the tumor markers CEA, CA19-9, CA724, CA125, and CYFRA 21-1 in the washing fluid of EUS-FNA with commonly used imaging methods can help distinguish benign and malignant pancreatic lesions.

Asymmetric crowders and membrane morphology at the nexus of intracellular trafficking and oncology

A definitive understanding of the interplay between protein binding/migration and membrane curvature evolution is emerging but needs further study. The mechanisms defining such phenomena are critical to intracellular transport and trafficking of proteins. Among trafficking modalities, exosomes have drawn attention in cancer research as these nano-sized naturally occurring vehicles are implicated in intercellular communication in the tumor microenvironment, suppressing anti-tumor immunity and preparing the metastatic niche for progression. A significant question in the field is how the release and composition of tumor exosomes are regulated. In this perspective article, we explore how physical factors such as geometry and tissue mechanics regulate cell cortical tension to influence exosome production by co-opting the biophysics as well as the signaling dynamics of intracellular trafficking pathways and how these exosomes contribute to the suppression of anti-tumor immunity and promote metastasis. We describe a multiscale modeling approach whose impact goes beyond the fundamental investigation of specific cellular processes toward actual clinical translation. Exosomal mechanisms are critical to developing and approving liquid biopsy technologies, poised to transform future non-invasive, longitudinal profiling of evolving tumors and resistance to cancer therapies to bring us one step closer to the promise of personalized medicine.

The NF-κB/NUAK2 signaling axis regulates pancreatic cancer progression by targeting SMAD2/3

Nuclear factor kappa B (NF-κB) plays a pivotal role in the development of pancreatic cancer, and its phosphorylation has previously been linked to the regulation of NUAK2. However, the regulatory connection between NF-κB and NUAK2, as well as NUAK2's role in pancreatic cancer, remains unclear. In this study, we observed that inhibiting NUAK2 impeded the proliferation, migration, and invasion of pancreatic cancer cells while triggering apoptosis. NUAK2 overexpression partially resisted apoptosis and reversed the inhibitory effects of the NF-κB inhibitor. NF-κB transcriptionally regulated NUAK2 transcription by binding to the promoter region of NUAK2. Mechanistically, NUAK2 knockdown remarkably reduced the expression levels of p-SMAD2/3 and SMAD2/3, resulting in decreased nuclear translocation of SMAD4. In SMAD4-negative cells, NUAK2 knockdown impacted FAK signaling by downregulating SMAD2/3. Moreover, NUAK2 knockdown heightened the sensitivity of pancreatic cancer cells to gemcitabine, suggesting that NUAK2 inhibitors could be a promising strategy for pancreatic cancer treatment.

Free energy calculations for membrane morphological transformations and insights to physical biology and oncology

In this chapter, we aim to bridge basic molecular and cellular principles surrounding membrane curvature generation with rewiring of cellular signals in cancer through multiscale models. We describe a general framework that integrates signaling with other cellular functions like trafficking, cell-cell and cell-matrix adhesion, and motility. The guiding question in our approach is: how does a physical change in cell membrane configuration caused by external stimuli (including those by the extracellular microenvironment) alter trafficking, signaling and subsequent cell fate? We answer this question by constructing a modeling framework based on stochastic spatial continuum models of cell membrane deformations. We apply this framework to explore the link between trafficking, signaling in the tumor microenvironment, and cell fate. At each stage, we aim to connect the results of our predictions with cellular experiments.

SMAD4 loss predicts worse overall and distant metastasis-free survival in patients with resected pancreatic adenocarcinoma

BACKGROUND

In select patients, pancreatic adenocarcinoma remains a local disease, yet there are no validated biomarkers to predict this behavior and who may benefit from aggressive local treatments. This study sought to determine if SMAD4 (mothers against decapentaplegic homolog 4) messenger RNA-sequencing (RNA-seq) expression is a robust method for predicting overall survival (OS) and distant metastasis-free survival (DMFS) in patients with resected pancreatic adenocarcinoma.

METHODS

Utilizing The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC), 322 patients with resected stage I-III pancreatic adenocarcinoma were identified. In TCGA, multivariable proportional hazards models were used to determine the association of SMAD4 genomic aberrations and RNA-seq expression with OS and DMFS. In the ICGC, analysis sought to confirm the predictive performance of RNA-seq via multivariable models and receiver operator characteristic curves.

RESULTS

In TCGA, the presence of SMAD4 genomic aberrations was associated with worse OS (hazard ratio [HR], 1.55; 95% CI, 1.00-2.40; p = .048) but not DMFS (HR, 1.33; 95% CI, .87-2.03; p = .19). Low SMAD4 RNA-seq expression was associated with worse OS (HR, 1.83; 95% CI, 1.17-2.86; p = .008) and DMFS (HR, 1.70; 95% CI, 1.14-2.54; p = .009). In the ICGC, increased SMAD4 RNA-seq expression correlated with improved OS (area under the curve [AUC], .92; 95% CI, .86-.94) and DMFS (AUC, .84; 95% CI, .82-.87).

CONCLUSIONS

In patients with resected pancreatic adenocarcinoma, SMAD4 genomic aberrations are associated with worse OS but do not predict for DMFS. Increased SMAD4 RNA-seq expression is associated with improved OS and DMFS in patients with resected pancreatic adenocarcinoma. This reproducible finding suggests SMAD4 RNA-seq expression may be a useful marker to predict metastatic spread.

SMAD4 Positive Pancreatic Ductal Adenocarcinomas Are Associated with Better Outcomes in Patients Receiving FOLFIRINOX-Based Neoadjuvant Therapy

BACKGROUND

SMAD4 is inactivated in 50-55% of pancreatic ductal adenocarcinomas (PDACs). SMAD4 loss of expression has been described as a negative prognostic factor in PDAC associated with an increased rate of metastasis and resistance to therapy. However, the impact of SMAD4 inactivation in patients receiving neoadjuvant therapy (NAT) is not well characterized. The aim of our study was to investigate whether SMAD4 status is a prognostic and predictive factor in patients receiving NAT.

METHODS

We retrospectively analyzed 59 patients from a single center who underwent surgical resection for primary PDAC after NAT. SMAD4 nuclear expression was assessed by immunohistochemistry, and its relationship to clinicopathologic variables and survival parameters was evaluated. Interaction testing was performed between SMAD4 status and the type of NAT.

RESULTS

49.15% of patients presented loss of SMAD4. SMAD4 loss was associated with a higher positive lymph node ratio (p = 0.03), shorter progression-free survival (PFS) (p = 0.02), and metastasis-free survival (MFS) (p = 0.02), but it was not an independent prognostic biomarker in multivariate analysis. Interaction tests demonstrated that patients with SMAD4-positive tumors receiving FOLFIRINOX-based NAT showed the best outcome.

CONCLUSION

This study highlights the potential prognostic and predictive role of SMAD4 status in PDAC patients receiving FOLFIRINOX-based NAT.

Clinical Impact of Preoperative Biliary Drainage in Patients with Ductal Adenocarcinoma of the Pancreatic Head

Our aim was to study the association between preoperative biliary drainage (PBD) and morbidity following cephalic pancreaticoduodenectomy (CPD) for pancreatic ductal adenocarcinoma (PDAC) and its prognostic impact, which is still controversial in the literature. A retrospective study was conducted, which included 128 patients who underwent CPD for PDAC, divided into two groups: those who underwent PBD (group 1) and those who did not undergo this procedure (group 2). Group 1 was subdivided according to the drainage route: endoscopic retrograde cholangiopancreatography (ERCP), group 1.1, and percutaneous transhepatic cholangiography (PTC), group 1.2. 34.4% of patients underwent PBD, and 47.7% developed PBD-related complications, with 37% in group 1.1 and 64.7% in group 1.2 (p = 0.074). There was a significant difference between group 1 and 2 regarding bacterial colonization of the bile (45.5% vs. 3.6%, p < 0.001), but no difference was found in the colonization by multidrug-resistant bacteria, the development of Clavien–Dindo ≥ III complications, clinically relevant pancreatic fistula and delayed gastric emptying (DGE), intra-abdominal abscess, hemorrhage, superficial surgical site infection (SSI), and readmission. Between groups 1.1 and 1.2, there was a significant difference in clinically relevant DGE (44.4% vs. 5.9%, p = 0.014) and Clavien–Dindo ≥ III complications (59.3% vs. 88.2%, p = 0.040). There were no significant differences in median overall survival and disease-free survival (DFS) between groups 1 and 2. Groups 1.1 and 1.2 had a significant difference in DFS (10 vs. 5 months, p = 0.017). In this group of patients, PBD was associated with increased bacterial colonization of the bile, without a significant increase in postoperative complications or influence in survival. ERCP seems to contribute to the development of clinically significant DGE. Patients undergoing PTC appear to have an early recurrence.

An 8q24 Gain in Pancreatic Juice Is a Candidate Biomarker for the Detection of Pancreatic Cancer

Secretin-stimulated pancreatic juice (PJ), collected from the duodenum, presents a valuable biomarker source for the (earlier) detection of pancreatic cancer (PC). Here, we evaluate the feasibility and performance of shallow sequencing to detect copy number variations (CNVs) in cell-free DNA (cfDNA) from PJ for PC detection. First, we confirmed the feasibility of shallow sequencing in PJ (n = 4), matched plasma (n = 3) and tissue samples (n = 4, microarray). Subsequently, shallow sequencing was performed on cfDNA from PJ of 26 cases (25 sporadic PC, 1 high-grade dysplasia) and 19 controls with a hereditary or familial increased risk of PC. 40 of the 45 PJ samples met the quality criteria for cfDNA analysis. Nine individuals had an 8q24 gain (oncogene MYC; 23%; eight cases (33%) and one control (6%), p = 0.04); six had both a 2q gain (STAT1) and 5p loss (CDH10; 15%; four cases (7%) and two controls (13%), p = 0.72). The presence of an 8q24 gain differentiated the cases and controls, with a sensitivity of 33% (95% CI 16-55%) and specificity of 94% (95% CI 70-100%). The presence of either an 8q24 or 2q gain with a 5p loss was related to a sensitivity of 50% (95% CI 29-71%) and specificity of 81% (95% CI 54-96%). Shallow sequencing of PJ is feasible. The presence of an 8q24 gain in PJ shows promise as a biomarker for the detection of PC. Further research is required with a larger sample size and consecutively collected samples in high-risk individuals prior to implementation in a surveillance cohort.

Tumor Stroma Area and Other Prognostic Factors in Pancreatic Ductal Adenocarcinoma Patients Submitted to Surgery

Pancreatic ductal adenocarcinoma (PDAC) has a dense stroma, responsible for up to 80% of its volume. The amount of stroma can be associated with prognosis, although there are discrepancies regarding its concrete impact. The aim of this work was to study prognostic factors for PDAC patients submitted to surgery, including the prognostic impact of the tumor stroma area (TSA). A retrospective study with PDAC patients submitted for surgical resection was conducted. The TSA was calculated using QuPath-0.2.3 software. Arterial hypertension, diabetes mellitus, and surgical complications Clavien-Dindo>IIIa are independent risk factors for mortality in PDAC patients submitted to surgery. Regarding TSA, using >1.9 × 10¹¹ µ² as cut-off value for all stages, patients seem to have longer overall survival (OS) (31 vs. 21 months, p = 0.495). For stage II, a TSA > 2 × 10¹¹ µ² was significantly associated with an R0 resection (p = 0.037). For stage III patients, a TSA > 1.9 × 10¹¹ µ² was significantly associated with a lower histological grade (p = 0.031), and a TSA > 2E + 11 µ² was significantly associated with a preoperative AP ≥ 120 U/L (p = 0.009) and a lower preoperative AST (≤35 U/L) (p = 0.004). Patients with PDAC undergoing surgical resection with preoperative CA19.9 > 500 U/L and AST ≥ 100 U/L have an independent higher risk of recurrence. Tumor stroma could have a protective effect in these patients. A larger TSA is associated with an R0 resection in stage II patients and a lower histological grade in stage III patients, which may contribute to a longer OS.

SMAD2/3 mediate oncogenic effects of TGF-β in the absence of SMAD4

TGF-β signaling is involved in pancreatic ductal adenocarcinoma (PDAC) tumorigenesis, representing one of the four major pathways genetically altered in 100% of PDAC cases. TGF-β exerts complex and pleiotropic effects in cancers, notably via the activation of SMAD pathways, predominantly SMAD2/3/4. Though SMAD2 and 3 are rarely mutated in cancers, SMAD4 is lost in about 50% of PDAC, and the role of SMAD2/3 in a SMAD4-null context remains understudied. We herein provide evidence of a SMAD2/3 oncogenic effect in response to TGF-β1 in SMAD4-null human PDAC cancer cells. We report that inactivation of SMAD2/3 in SMAD4-negative PDAC cells compromises TGF-β-driven collective migration mediated by FAK and Rho/Rac signaling. Moreover, RNA-sequencing analyses highlight a TGF-β gene signature related to aggressiveness mediated by SMAD2/3 in the absence of SMAD4. Using a PDAC patient cohort, we reveal that SMAD4-negative tumors with high levels of phospho-SMAD2 are more aggressive and have a poorer prognosis. Thus, loss of SMAD4 tumor suppressive activity in PDAC leads to an oncogenic gain-of-function of SMAD2/3, and to the onset of associated deleterious effects.

In pancreatic ductal adenocarcinoma cells and patient tissue, SMAD2/3 is shown to mediate oncogenic effects of TGF-β in the absence of SMAD4.

Isolated Pancreatic Metastases of Renal Cell Cancer: Genetics and Epigenetics of an Unusual Tumour Entity

Isolated pancreatic metastases of renal cell carcinoma (isPMRCC) are a rare manifestation of metastatic renal cell carcinoma (mRCC) characterized by two peculiarities: (1). The definite or at least long-term exclusive occurrence of metastases in the pancreas and (2). an unusual low tumour aggressiveness with slow tumour progression and consecutive, good treatment results. According to current knowledge, the exclusive occurrence of pancreatic metastases is due to a highly specific and highly selective seed and soil mechanism, which does not allow metastases settlement outside the pancreas, and whose detailed genetic/epigenetic causes are not yet elucidated. Recent studies have shed light on some of the pathways involved for the protracted course of the disease and highlighted a special genetic profile (lack of loss of 9p, lower weight genome instability index, low frequency of BAP1 alterations, and a high frequency of PBRM1 loss), which deviates from the conventional mRCC profile. Finally, the question of the reasons for the long-term relative genetic stability of the involved cell clones, which is an essential prerequisite for a favourable prognosis, remains unanswered.

Pancreatic cancer evolution and heterogeneity: integrating omics and clinical data

Pancreatic ductal adenocarcinoma (PDAC), already among the deadliest epithelial malignancies, is rising in both incidence and contribution to overall cancer deaths. Decades of research have improved our understanding of PDAC carcinogenesis, including characterizing germline predisposition, the cell of origin, precursor lesions, the sequence of genetic alterations, including simple and structural alterations, transcriptional changes and subtypes, tumour heterogeneity, metastatic progression and the tumour microenvironment. These fundamental advances inform contemporary translational efforts in primary prevention, screening and early detection, multidisciplinary management and survivorship, as prospective clinical trials begin to adopt molecular-based selection criteria to guide targeted therapies. Genomic and transcriptomic data on PDAC were also included in the international pan-cancer analysis of approximately 2,600 cancers, a milestone in cancer research that allows further insight through comparison with other tumour types. Thus, this is an ideal time to review our current knowledge of PDAC evolution and heterogeneity, gained from the study of preclinical models and patient biospecimens, and to propose a model of PDAC evolution that takes into consideration findings from varied sources, with a particular focus on the genomics of human PDAC.

The Role of SMAD4 Inactivation in Epithelial-Mesenchymal Plasticity of Pancreatic Ductal Adenocarcinoma: The Missing Link?

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is currently one of the deadliest cancers. Despite the progress that has been made in the research of patient care and the understanding of pancreatic cancer, the survival rate remains mediocre. SMAD4, a tumor-suppressor gene, is specifically inactivated in 50–55% of pancreatic cancers. The role of SMAD4 protein loss in PDAC remains controversial, but seems to be associated with worse overall survival and metastasis. Here, we review the function of SMAD4 inactivation in the context of a specific biological process called epithelial–mesenchymal transition, as it has been increasingly associated with tumor formation, metastasis and resistance to therapy. By improving our understanding of these molecular mechanisms, we hope to find new targets for therapy and improve the care of patients with PDAC.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) presents a five-year survival rate of 10% and its incidence increases over the years. It is, therefore, essential to improve our understanding of the molecular mechanisms that promote metastasis and chemoresistance in PDAC, which are the main causes of death in these patients. SMAD4 is inactivated in 50% of PDACs and its loss has been associated with worse overall survival and metastasis, although some controversy still exists. SMAD4 is the central signal transducer of the transforming growth factor-beta (TGF-beta) pathway, which is notably known to play a role in epithelial–mesenchymal transition (EMT). EMT is a biological process where epithelial cells lose their characteristics to acquire a spindle-cell phenotype and increased motility. EMT has been increasingly studied due to its potential implication in metastasis and therapy resistance. Recently, it has been suggested that cells undergo EMT transition through intermediary states, which is referred to as epithelial–mesenchymal plasticity (EMP). The intermediary states are characterized by enhanced aggressiveness and more efficient metastasis. Therefore, this review aims to summarize and analyze the current knowledge on SMAD4 loss in patients with PDAC and to investigate its potential role in EMP in order to better understand its function in PDAC carcinogenesis.

Immunohistochemical Loss of DPC4 in Tumors With Mucinous Differentiation Arising in or Involving the Gynecologic Tract

DPC4 immunohistochemistry (IHC) is usually part of the work-up of mucinous neoplasms in the ovary where the distinction between an ovarian primary and metastatic pancreaticobiliary adenocarcinoma (PanACa) must be made. Although DPC4 IHC is lost in about 55% (46%-61%) of PanACas and typically retained in most primary ovarian mucinous neoplasms, no study has evaluated the expression of this marker in a large cohort of neoplasms arising in or involving gynecologic (GYN) organs. In this study, we retrospectively analyzed the expression of DPC4 IHC in a total of 251 tumors and lesions related to the GYN tract in which DPC4 IHC stain was performed during the initial pathology evaluation. Of these, 138 were primary GYN tumors and lesions, 31 were metastatic GYN tumors involving non-GYN sites, and 83 were metastatic non-GYN tumors involving the GYN tract. We identified 27 cases with loss of DPC4 IHC expression of which 20 cases met the inclusion criteria (i.e. clinical information was available to determine the site of tumor origin). We observed that loss of DPC4 nuclear expression was most commonly seen in tumors of endocervical origin (n=7), of which 5 were gastric-type cervical adenocarcinomas (GCxACa) and 2 were usual-type cervical adenocarcinomas, either primary or metastatic. This was followed by tumors of the pancreaticobiliary tract (n=5), ovary (n=2), and appendix (n=1). In addition, 1 gastric-type vaginal adenocarcinoma (GVaACa) also showed loss of DPC4. Our findings indicate that in female patients with mucinous neoplasms involving the ovary or other sites, with loss of DPC4 by IHC, and negative pancreaticobiliary imaging, the possibility of an occult GCx/GVaACa, and rarely an ovarian primary must be considered.

TGFβ Signaling in the Pancreatic Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is associated with poor clinical outcomes, largely attributed to incomplete responses to standard therapeutic approaches. Recently, selective inhibitors of the Transforming Growth Factor β (TGFβ) signaling pathway have shown early promise in the treatment of PDAC, particularly as a means of augmenting responses to chemo- and immunotherapies. However, TGFβ is a potent and pleiotropic cytokine with several seemingly paradoxical roles within the pancreatic tumor microenvironment (TME). Although TGFβ signaling can have potent tumor-suppressive effects in epithelial cells, TGFβ signaling also accelerates pancreatic tumorigenesis by enhancing epithelial-to-mesenchymal transition (EMT), fibrosis, and the evasion of the cytotoxic immune surveillance program. Here, we discuss the known roles of TGFβ signaling in pancreatic carcinogenesis, the biologic consequences of the genetic inactivation of select components of the TGFβ pathway, as well as past and present attempts to advance TGFβ inhibitors in the treatment of PDAC patients.

Association of SMAD4 loss with drug resistance in clinical cancer patients: A systematic meta-analysis

Background

Drug resistance frequently led to the failure of chemotherapy for malignant cancers, hence causing cancer relapse. Thus, understanding mechanism of drug resistance in cancer is vital to improve the treatment efficacy. Here, we aim to evaluate the association between SMAD4 expression and the drug resistance in cancers by performing a meta-analysis.

Method

Relevant studies detecting SMAD4 expression in cancer patients treated with chemo-drugs up till December 2020 were systematically searched in four common scientific databases using selected keywords. The pooled hazard ratio (HR) was the ratio of hazard rate between SMAD4^neg population vs SMAD4^pos population. The HRs and risk ratios (RRs) with 95% confidence intervals (CIs) were used to explore the association between SMAD4 expression losses with drug resistance in cancers.

Result

After an initial screening according to the inclusion and exclusion criteria, eleven studies were included in the meta-analysis. There were a total of 2092 patients from all the included studies in this analysis. Results obtained indicated that loss of SMAD4 expression was significantly correlated with drug resistance with pooled HRs (95% CI) of 1.23 (1.01–1.45), metastasis with pooled RRs (95% CI) of 1.10 (0.97–1.25) and recurrence with pooled RRs (95% CI) of 1.32 (1.06–1.64). In the subgroup analysis, cancer type, drug type, sample size and antibody brand did not affect the significance of association between loss of SMAD4 expression and drug resistance. In addition, there was no evidence of publication bias as suggested by Begg’s test.

Conclusion

Findings from our meta-analysis demonstrated that loss of SMAD4 expression was correlated with drug resistance, metastasis and recurrence. Therefore, SMAD4 expression could be potentially used as a molecular marker for cancer resistance.

Benign vs malignant pancreatic lesions: Molecular insights to an ongoing debate

Several benign conditions such as chronic pancreatitis, autoimmune pancreatitis, and paraduodenal pancreatitis can present as mass lesions and may mimic pancreatic ductal adenocarcinoma (PDAC) clinically and radiologically. Thorough histologic examination with attention to certain morphologic features can assist in deciphering neoplastic from reactive, however small biopsies often remain a challenge. Variable histologic patterns in conventional PDAC may also confound the diagnosis of PDAC. Uncommon subtypes of pancreatic carcinoma such as adenosquamous and squamous cell carcinoma, colloid carcinoma, medullary carcinoma, hepatoid carcinoma and signet ring cell carcinoma necessitate excluding metastasis from other sites prior to rendering the diagnosis of pancreatic carcinoma. The use of immunohistochemical staining and molecular markers can aid in separating benign from malignant and PDAC from metastasis. PDAC expresses a few non-specific epithelial and mucin immunomarkers such as CK7, CK19, MUC1, MUC4 and MUC5AC. However, the only immunohistochemical marker that is specific for PDAC in the right clinical context is SMAD4. Loss of SMAD4 within atypical glands and ducts supports the diagnosis of PDAC in a limited sample. Unfortunately, this finding is seen only in 50% of PDAC cases. The identification of certain mutations can help support a diagnosis of PDAC when benign conditions are in the differential. At the molecular level, KRAS oncogene mutations are seen in approximately 93% of PDACs. Subsequent neoplastic progression is driven by additional mutations of tumor suppressor genes, such as CDKN2A, TP53, and SMAD4. Molecular markers can also provide an insight to the prognosis. For instance, the loss of SMAD4 is associated with a poor outcome whereas mutations in MLL, MLL2, MLL3, and ARID1A are associated with improved survival.

Correlation between loss of Smad4 and clinical parameters of non-small cell lung cancer: an observational cohort study

Background

SMAD4 has been found to be inactivated to varying degrees in many types of cancer; the purpose of this study was to investigate the correlation between SMAD4 expression in non-small cell lung cancer (NSCLC) and clinical pathological parameters.

Methods

The serum concentration of SMAD4 was measured by enzyme-linked immunosorbent assay and its histological expression was quantified by immunohistochemistry.

Results

The serum concentration of Smad4 in patients with NSCLC was lower than that in benign lung disease patients and healthy individuals (P < 0.001) and its concentration was related to the histological classification, pathological differentiation, lymphatic metastasis and clinical stage of NSCLC. The sensitivity and specificity of serum Smad4 were 91.56% and 61.56% for screening NSCLC from healthy individuals and 84.55% and 60.36% for screening NSCLC from patients with benign lung disease. Logistic regression analysis showed that the degree of cell differentiation (P < 0.001), lymph node metastasis (P < 0.001) and clinical stage of NSCLC (P = 0.007) affected the expression of Smad4, and had a strong correlation with the expression of Smad4. The expression of Smad4 in NSCLC tissues was lower than that in normal lung tissues (P = 0.009) and its expression was related to the degree of tissue differentiation, lymph node metastasis and clinical stage (P < 0.05).

Conclusions

The downregulation or deletion of Smad4 is related to the malignant biological behavior of NSCLC and serum Smad4 could be considered as a potential molecular indicator for diagnosis and evaluation of NSCLC.

High expression of krüppel-like factor 10 or Smad4 predicts clinical benefit of adjuvant chemoradiotherapy in curatively resected pancreatic adenocarcinoma: From a randomized phase III trial

PURPOSE

Our previous studies have demonstrated that Krüppel-like factor 10 (Klf10) modulated tumor radiation resistance and helps to predict clinical outcomes of pancreatic adenocarcinoma (PDAC). This study aimed to evaluate whether the expression levels of Klf10, Smad4 and Runx3 can help predict the benefits of adjuvant chemoradiotherapy (CRT) in resected PDAC.

METHODS AND MATERIALS

Tissue specimens were collected from 111 patients with curatively resected PDAC who were enrolled into a randomized trial comparing adjuvant gemcitabine with or without CRT. Immunohistochemical expression of biomarkers was quantified by pathologists blinded to patient outcomes through a grading system based on the extent and intensity of staining. The predictive value of biomarkers was analyzed using SAS statistical software.

RESULTS

In total, 56 and 55 patients received adjuvant gemcitabine alone and additional CRT, respectively. The expression levels of Klf10, Smad4 and postoperative CA19-9 were significantly correlated with overall survival (OS) (p = 0.013, 0.045, and 0.047, respectively). Multivariable analysis showed that the expression level of postoperative serum CA19-9 and tumor tissue Klf10 expression level were significant predictors for OS (p = 0.038, and 0.028, respectively). Patients with high Klf10 or Smad4 (n = 55), had a significantly better local recurrence-free survival (∞ vs 19.8 months; p = 0.026) and a longer OS (33.0 vs 23.0 months; p = 0.12) if they received additional adjuvant CRT than gemcitabine only. The results were similar after adjusted by postoperative level of CA19-9.

CONCLUSION

Patients with curatively resected PDAC and a high expression of either Klf10 or Smad4 have high chances of benefiting from adjuvant CRT. Combining Klf10 and Smad4 to predict the benefits of adjuvant CRT in resected PDAC deserves further validation.

An overview of genetic mutations and epigenetic signatures in the course of pancreatic cancer progression

Pancreatic cancer (PC) is assumed to be an intimidating and deadly malignancy due to being the leading cause of cancer-led mortality, predominantly affecting males of older age. The overall (5 years) survival rate of PC is less than 9% and is anticipated to be aggravated in the future due to the lack of molecular acquaintance and diagnostic tools for its early detection. Multiple factors are involved in the course of PC development, including genetics, cigarette smoking, alcohol, family history, and aberrant epigenetic signatures of the epigenome. In this review, we will mainly focus on the genetic mutations and epigenetic signature of PC. Multiple tumor suppressor and oncogene mutations are involved in PC initiation, including K-RAS, p53, CDKN2A, and SMAD4. The mutational frequency of these genes ranges from 50 to 98% in PC. The nature of mutation diagnosis is mostly homozygous deletion, point mutation, and aberrant methylation. In addition to genetic modification, epigenetic alterations particularly aberrant hypermethylation and hypomethylation also predispose patients to PC. Hypermethylation is mostly involved in the downregulation of tumor suppressor genes and leads to PC, while multiple genes also represent a hypomethylation status in PC. Several renewable drugs and detection tools have been developed to cope with this aggressive malady, but all are futile, and surgical resection remains the only choice for prolonged survival if diagnosed before metastasis. However, the available therapeutic development is insufficient to cure PC. Therefore, novel approaches are a prerequisite to elucidating the genetic and epigenetic mechanisms underlying PC progression for healthier lifelong survival.

Molecular Alterations in Pancreatic Cancer: Transfer to the Clinic

Pancreatic ductal adenocarcinoma (PDA) is the most common cancer of the exocrine pancreas and probably the tumor that has benefited the least from clinical progress in the last three decades. A consensus has been reached regarding the histologic classification of the ductal preneoplastic lesions (pancreatic intra-epithelial neoplasia-PanIN) and the molecular alterations associated with them. Mutations in KRAS and inactivation of CDKN2A, SMAD4 and TP53 are among the most prevalent alterations. Next generation sequencing studies are providing a broad picture of the enormous heterogeneity in this tumor type, describing new mutations less prevalent. These studies have also allowed the characterization of different subtypes with prognostic value. However, all this knowledge has not been translated into a clinical progress. Effective preventive and early diagnostic strategies are essential to improve the survival rates. The main challenge is, indeed, to identify new effective drugs. Despite many years of research and its limited success, gemcitabine is still the first line treatment of PDA. New drug combinations and new concepts to improve drug delivery into the tumor, as well as the development of preclinical predictive assays, are being explored and provide optimism and prospects for better therapies.

Endoscopic ultrasound-guided therapies for pancreatic solid tumors: An overview

The close proximity of the endoscopic ultrasound (EUS) probe to the pancreas, coupled with the ease with which a needle can be inserted into a pancreatic lesion, have contributed to the development of EUS-guided therapies for both adenocarcinoma and neuroendocrine pancreatic neoplasms. EUS-guided fine needle injection of different types of drugs, implantation of fiducial markers to facilitate stereotactic body radiation therapy or of radioactive seeds to perform brachytherapy, and the use of different thermal and nonthermal ablation devices and techniques have all been tested in preliminary human studies. This manuscript will present the available evidence accumulated thus far in the field of EUS-guided oncological treatment of pancreatic solid tumors, along with a look into possible future applications.

Delving into Early-onset Pancreatic Ductal Adenocarcinoma: How Does Age Fit In?

PURPOSE

With the rising incidence of early-onset pancreatic cancer (EOPC), molecular characteristics that distinguish early-onset pancreatic ductal adenocarcinoma (PDAC) tumors from those arising at a later age are not well understood.

EXPERIMENTAL DESIGN

We performed bioinformatic analysis of genomic and transcriptomic data generated from 269 advanced (metastatic or locally advanced) and 277 resectable PDAC tumor samples. Patient samples were stratified into EOPC (age of onset ≤55 years; n = 117), intermediate (age of onset 55-70 years; n = 264), and average (age of onset ≥70 years; n = 165) groups. Frequency of somatic mutations affecting genes commonly implicated in PDAC, as well as gene expression patterns, were compared between EOPC and all other groups.

RESULTS

EOPC tumors showed significantly lower frequency of somatic single-nucleotide variant (SNV)/insertions/deletions (indel) in CDKN2A (P = 0.0017), and were more likely to achieve biallelic mutation of CDKN2A through homozygous copy loss as opposed to heterozygous copy loss coupled with a loss-of-function SNV/indel mutation, the latter of which was more common for tumors with later ages of onset (P = 1.5e-4). Transcription factor forkhead box protein C2 (FOXC2) was significantly upregulated in EOPC tumors (P = 0.032). Genes significantly correlated with FOXC2 in PDAC samples were enriched for gene sets related to epithelial-to-mesenchymal transition (EMT) and included VIM (P = 1.8e-8), CDH11 (P = 6.5e-5), and CDH2 (P = 2.4e-2).

CONCLUSIONS

Our comprehensive analysis of sequencing data generated from a large cohort of PDAC patient samples highlights a distinctive pattern of biallelic CDKN2A mutation in EOPC tumors. Increased expression of FOXC2 in EOPC, with the correlation between FOXC2 and EMT pathways, represents novel molecular characteristics of EOPC.See related commentary by Lou, p. 8.

Prognostic Biomarkers for Pancreatic Ductal Adenocarcinoma: An Umbrella Review

Background: Pancreatic ductal adenocarcinoma (PDAC) leads to the majority of cancer-related deaths due to its morbidity with similar mortality. Lack of effective prognostic biomarkers are the main reason for belated post-operative intervention of recurrence which causes high mortality. Numerous systematic reviews and meta-analyses have explored the prognostic value of biomarkers in PDAC so far. In this article, we performed an umbrella review analyzing these studies to provide an overview of associations between prognostic biomarkers and PDAC survival outcome and synthesized these results to guide better clinical practice.

Methods: Systematic reviews and meta-analyses investigating the associations between PDAC survival outcomes and prognostic biomarkers were acquired via the PubMed and Embase databases from inception till February 1, 2020. Associations supported by nominally statistically significant results were classified into strong, highly suggestive, suggestive, and weak based on several critical factors such as the statistical significance of summary estimates, the number of events, the estimate of the largest study included, interstudy heterogeneity, small-study effects, 95% predictive interval (PI), excess significance bias, and the results of credibility ceiling sensitivity analyses.

Results: We included 41 meta-analyses containing 63 associations between PDAC survival outcomes and prognostic biomarkers. Although, none was supported by strong evidence among these associations, an association between C-reactive protein to albumin ratio (CAR) and PDAC overall survival (OS) and an association between neutrophil-lymphocyte ratio (NLR) and PDAC OS were supported by highly suggestive evidence. Otherwise, the association between lactate dehydrogenase (LDH) and PDAC OS was supported by suggestive evidence. The remaining 60 associations were supported by weak or not suggestive evidence.

Conclusion: Associations between CAR or NLR and PDAC OS were supported by highly suggestive evidence. And the association between LDH and PDAC OS was supported by suggestive evidence. Although the methodological quality of the included systematic reviews and meta-analyses which were evaluated by AMSTAR2.0 is generally poor, the identification of the relatively robust prognostic biomarkers of PDAC may guide better post-operative intervention and follow-up to prolong patients' survival.

Proteomic and genomic profiling of pancreatic cancer

Pancreatic cancer remains the most fatal human tumor type. The aggressive tumor biology coupled with the lack of early detection strategies and effective treatment are major reasons for the poor survival rate. Collaborative research efforts have been devoted to understand pancreatic cancer at the molecular level. Large-scale genomic studies have generated important insights into the genetic drivers of pancreatic cancer. In the post-genomic era, protein sequencing of tumor tissue, cell lines, pancreatic juice, and blood from patients with pancreatic cancer has provided a fundament for the development of new diagnostic and prognostic biomarkers. The integration of mass spectrometry and genomic sequencing strategies may help characterize protein identities and post-translational modifications that relate to a specific mutation. Consequently, proteomic and genomic techniques have become a compulsory requirement in modern medicine and health care. These types of proteogenomic studies may usher in a new era of precision diagnostics and treatment in patients with pancreatic cancer.

Clinicopathological Characterization and Prognostic Implication of SMAD4 Expression in Colorectal Carcinoma

Background

SMAD family member 4 (SMAD4) has gained attention as a promising prognostic factor of colorectal cancer (CRC) as well as a key molecule to understand the tumorigenesis and progression of CRC.

Methods

We retrospectively analyzed 1,281 CRC cases immunohistochemically for their expression status of SMAD4, and correlated this status with clinicopathologic and molecular features of CRCs.

Results

A loss of nuclear SMAD4 was significantly associated with frequent lymphovascular and perineural invasion, tumor budding, fewer tumor-infiltrating lymphocytes, higher pT and pN category, and frequent distant metastasis. In contrast, tumors overexpressing SMAD4 showed a significant association with sporadic microsatellite instability. After adjustment for TNM stage, tumor differentiation, adjuvant chemotherapy, and lymphovascular invasion, the loss of SMAD4 was found to be an independent prognostic factor for worse 5-year progression-free survival (hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.01 to 1.60; p=.042) and 7-year cancer-specific survival (HR, 1.45; 95% CI, 1.06 to 1.99; p=.022).

Conclusions

We confirmed the value of determining the loss of SMAD4 immunohistochemically as an independent prognostic factor for CRC in general. In addition, we identified some histologic and molecular features that might be clues to elucidate the role of SMAD4 in colorectal tumorigenesis and progression.

Integration of Genomic and Transcriptional Features in Pancreatic Cancer Reveals Increased Cell Cycle Progression in Metastases

We integrated clinical, genomic, and transcriptomic data from 224 primaries and 95 metastases from 289 patients to characterize progression of pancreatic ductal adenocarcinoma (PDAC). Driver gene alterations and mutational and expression-based signatures were preserved, with truncations, inversions, and translocations most conserved. Cell cycle progression (CCP) increased with sequential inactivation of tumor suppressors, yet remained higher in metastases, perhaps driven by cell cycle regulatory gene variants. Half of the cases were hypoxic by expression markers, overlapping with molecular subtypes. Paired tumor heterogeneity showed cancer cell migration by Halstedian progression. Multiple PDACs arising synchronously and metachronously in the same pancreas were actually intra-parenchymal metastases, not independent primary tumors. Established clinical co-variates dominated survival analyses, although CCP and hypoxia may inform clinical practice.

Genomic Landscape of Pancreatic Adenocarcinoma in Younger versus Older Patients: Does Age Matter?

PURPOSE

State-of-the-art genomic analyses of pancreatic adenocarcinoma (PDAC) have yielded insight into signaling pathways underlying carcinogenesis. PDAC is characterized by substantial genomic heterogeneity. We aimed to determine whether early-onset PDAC (EOPC; ≤55 years) displays a distinctive molecular landscape from average-age onset PDAC (AOPC; ≥70 years).

EXPERIMENTAL DESIGN

Three distinct datasets for PDAC were analyzed. In the first, patients undergoing treatment at Memorial Sloan Kettering (MSK) were consented for MSK-IMPACT next-generation sequencing. The second cohort analyzed was The Cancer Genome Atlas (TCGA) dataset for differences in somatic mutations, gene expression, and protein expression. The third dataset was an Australian cohort of PDAC. Clinical data were correlated with genomic analyses.

RESULTS

A total of 293 samples were analyzed, yielding 90 patients aged ≤55 years and 203 patients aged ≥70 years. Among the genes known to be associated with carcinogenesis, SMAD4 displayed higher mutation rates in younger patients. Comprehensive transcriptomic analysis of cellular pathways indicated that the TGFβ pathway has increased activation, and the expression levels of phospho-GSK3 were higher in EOPC. Survival outcomes revealed no differences between age groups.

CONCLUSIONS

These exploratory analyses suggest that there may be somatic gene alterations within the population of patients with early-onset PDAC that involve unique cellular pathways compared with average-onset PDAC. Former studies imply these cellular pathways may play a role in smoking-related PDAC carcinogenesis. Larger genomic datasets are warranted for future evaluation to extend these observations.

Immunohistochemical staining for S100P, SMAD4, and IMP3 on cell block preparations is sensitive and highly specific for pancreatic ductal adenocarcinoma

INTRODUCTION

The diagnosis of pancreatic ductal adenocarcinoma (PDA) on endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) material is often challenging. An immunohistochemical (IHC) panel may help establish the diagnosis of PDA in cases limited by sample size or ambiguous cytology. S100P, IMP3, and SMAD4 are 3 IHC markers that have shown promise as individual markers for PDA that have never been tested together as a panel. In this study, we evaluated the individual and combined efficacy of S100P, IMP3, and SMAD4 for the detection of PDA.

MATERIALS AND METHODS

S100P, IMP3, and SMAD4 IHC staining was performed on cell blocks (CBs) procured from pancreatic EUS-FNA procedures. The cohort included CBs that were diagnostic for PDA (n = 35), suspicious but nondiagnostic for PDA (n = 2), as well as CBs with benign pancreatic ductal epithelium (n = 12) and benign reactive pancreatic ductal epithelium (n = 18). A positive result for IMP3 and S100P was defined as moderate or strong staining of >10% of ductal cells. Complete lack of SMAD4 nuclear staining was considered a positive result-any nuclear SMAD4 staining was considered a negative result.

RESULTS

Two and 3 IHC marker panels were almost always more specific than individual IHC markers. Positivity for at least 2 of 3 IHC markers was a sensitive (91.89%) and highly specific (100%) marker of PDA.

CONCLUSIONS

The 3 IHC marker panel composed of S100P, IMP3, and SMAD4 is highly specific for PDA. Future studies should evaluate efficacy in a cohort with more atypical and suspicious cases.

Prognostic stratification of resected pancreatic ductal adenocarcinoma: Past, present, and future

Pancreatic ductal adenocarcinoma (PDAC) is the digestive cancer with the poorest prognosis, with a 5-year overall survival rate of 7%. Complete surgical resection followed by adjuvant chemotherapy is the only treatment with curative intent. However, many patients with an apparently localized disease who may undergo primary tumor resection already have micro-metastatic disease and will promptly develop metastases. Considering the significant rate of morbidity and mortality upon pancreatic surgery, the pre-operative identification of patients with an aggressive disease is therefore a major clinical issue. Although tumor size, differentiation, margins, and lymph node invasion are the main "classical" prognostic factors, they are not sufficient to fully predict early disease recurrence. In the last decade, multi-omics high-throughput analyses have provided a new insight into PDAC biology and have led to the description of multiple molecular subtypes, with a significant prognostic value for most of them, but that have not yet been transposed to routine clinical practice, mainly due to poor availability of tumor tissue material prior to surgical resection. In this review, we provide an overview of the current status of clinico-pathological and molecular biomarkers (tumor and blood) to predict early recurrence, and their implications for clinical practice and future research development.

Deletion of Smad4 reduces hepatic inflammation and fibrogenesis during nonalcoholic steatohepatitis progression

OBJECTIVE

To explore the effects of mothers against decapentaplegic homolog family member 4 (Smad4) deletion on inflammation and fibrogenesis in nonalcoholic steatohepatitis (NASH).

METHODS

Biopsied liver samples from NASH patients and normal liver tissue samples from patients who had received liver resection for trauma were collected. Smad4^Co/Co and wild-type (WT) mice were used to construct the NASH model using a high-fat diet (HFD) or methionine- and choline-deficient diet (MCD). HE staining and TUNEL assay were used to observe the pathological changes and cell apoptosis, respectively. Quantitative real-time polymerase chain reaction was used to detect the expression of inflammatory, fibrogenesis and apoptosis-related genes, and immunohistochemistry to determine the protein expression of SMAD4, MCP-1 and α-SMA.

RESULTS

SMAD4 protein expression significantly increased in NASH patients than in the control group. Compared with WT mice, HFD- and MCD-fed Smad4^Co/Co mice showed decreased hepatic steatosis, inflammation, liver cell apoptosis and nonalcoholic fatty liver activity score, reduced plasma glucose, triglyceride, free fatty acids, alanine aminotransferase and aspartate aminotransferase levels but increased adiponectin. Moreover, Smad4^Co/Co decreased the expression of inflammatory markers (TNF-α, MCP-1, IFN-γ), fibrogenetic markers (COL1A1, α-SMA and TGF-β1), lipogenic (Srebp1c, Fas and Acc) and proapoptotic genes (Bax and caspase-3), but increased the expression of β-oxidation (Ppar-α, Cpt1 and Aco) and antiapoptotic genes (Bcl-2).

CONCLUSION

Smad4 deletion may inhibit lipogenesis, stimulate β-oxidation, improve lipid metabolism and liver function, alleviate inflammation and fibrosis, and reduce cell apoptosis in NASH.

Mutations in Mitochondrial DNA From Pancreatic Ductal Adenocarcinomas Associate With Survival Times of Patients and Accumulate as Tumors Progress

Somatic mutations have been found in the mitochondria in different types of cancer cells, but it is not clear whether these affect tumorigenesis or tumor progression. We analyzed mitochondrial genomes of 268 early-stage, resected pancreatic ductal adenocarcinoma tissues and paired non-tumor tissues. We defined a mitochondrial somatic mutation (mtSNV) as a position where the difference in heteroplasmy fraction between tumor and normal sample was ≥0.2. Our analysis identified 304 mtSNVs, with at least 1 mtSNV in 61% (164 of 268) of tumor samples. The noncoding control region had the greatest proportion of mtSNVs (60 of 304 mutations); this region contains sites that regulate mitochondrial DNA transcription and replication. Frequently mutated genes included ND5, RNR2, and CO1, plus 29 mutations in transfer RNA genes. mtSNVs in 2 separate mitochondrial genes (ND4 and ND6) were associated with shorter overall survival time. This association appeared to depend on the level of mtSNV heteroplasmy. Non-random co-occurrence between mtSNVs and mutations in nuclear genes indicates interactions between nuclear and mitochondrial DNA. In an analysis of primary tumors and metastases from 6 patients, we found tumors to accumulate mitochondrial mutational mutations as they progress.

Pancreatic Cancer: Molecular Characterization, Clonal Evolution and Cancer Stem Cells

Pancreatic Ductal Adenocarcinoma (PDAC) is the fourth most common cause of cancer-related death and is the most lethal of common malignancies with a five-year survival rate of <10%. PDAC arises from different types of non-invasive precursor lesions: intraductal papillary mucinous neoplasms, mucinous cystic neoplasms and pancreatic intraepithelial neoplasia. The genetic landscape of PDAC is characterized by the presence of four frequently-mutated genes: KRAS, CDKN2A, TP53 and SMAD4. The development of mouse models of PDAC has greatly contributed to the understanding of the molecular and cellular mechanisms through which driver genes contribute to pancreatic cancer development. Particularly, oncogenic KRAS-driven genetically-engineered mouse models that phenotypically and genetically recapitulate human pancreatic cancer have clarified the mechanisms through which various mutated genes act in neoplasia induction and progression and have led to identifying the possible cellular origin of these neoplasias. Patient-derived xenografts are increasingly used for preclinical studies and for the development of personalized medicine strategies. The studies of the purification and characterization of pancreatic cancer stem cells have suggested that a minority cell population is responsible for initiation and maintenance of pancreatic adenocarcinomas. The study of these cells could contribute to the identification and clinical development of more efficacious drug treatments.

Combination immunohistochemistry for SMAD4 and Runt-related transcription factor 3 may identify a favorable prognostic subgroup of pancreatic ductal adenocarcinomas

Purposes

SMAD4/DPC4 mutations have been associated with aggressive behavior in pancreatic ductal adenocarcinomas (PDAC), and it has recently been suggested that RUNX3 expression combined with SMAD4 status may predict the metastatic potential of PDACs. We evaluated the prognostic utility of SMAD4/RUNX3 status in human PDACs by immunohistochemistry.

Materials and Methods

Immunohistochemical stains were performed for SMAD4 and RUNX3 on 210 surgically resected PDACs, and the results were correlated with the clinicopathological features.

Results

Loss of SMAD4 expression was associated with poor overall survival (OS) (p = 0.015) and progression-free survival (PFS) (p = 0.044). Nuclear RUNX3 expression was associated with decreased OS (p = 0.010) and PFS (p = 0.009), and more frequent in poorly differentiated PDACs (p = 0.037). On combining RUNX3/SMAD4 status, RUNX3-/SMAD4+ PDACs demonstrated longer OS (p = 0.008, median time; RUNX3-/SMAD4+ 34 months, others 17 months) and PFS (p = 0.009, median time; RUNX3-/SMAD4+ 29 months, others 8 months) compared to RUNX3+/SMAD4+ and SMAD4- groups; RUNX3-/SMAD4+ was a significant independent predictive factor for both OS [p = 0.025, HR 1.842 (95% CI 1.079-3.143)] and PFS [p = 0.020, HR 1.850 (95% CI 1.100-3.113)].

Conclusions

SMAD4-positivity with RUNX3-negativity was a significant independent predictive factor for favorable OS and PFS in PDAC. This is the first and large clinicopathological study of RUNX3/SMAD4 expression status in human PDAC. Combination immunohistochemistry for SMAD4 and RUNX3 may help identify a favorable prognostic subgroup of PDAC.

The Impact of SMAD4 Loss on Outcome in Patients with Advanced Pancreatic Cancer Treated with Systemic Chemotherapy

The role of the tumor suppressor mothers against decapentaplegic homolog 4 (SMAD4) has not yet been defined in patients (pts) with advanced pancreatic cancer (aPC). This translational research study was designed to evaluate the impact of tumoral SMAD4 loss on clinicopathological parameters and outcome in PC patients receiving palliative chemotherapy. Using immunohistochemistry, we examined SMAD4 expression in tumor tissue of 143 aPC pts treated within completed prospective clinical and biomarker trials. In uni- and multivariate analyses, SMAD4 expression status was correlated to clinicopathological patient characteristics and outcome. At chemotherapy initiation, 128 pts had metastatic PC; most pts (n = 99) received a gemcitabine-based regimen. SMAD4 loss was detected in 92 pts (64%); patient characteristics such as gender, age, tumor grading, disease stage or number of metastatic sites had no significant impact on tumoral SMAD4 status. In univariate analyses, SMAD4 loss had no impact on overall survival (hazard ratio (HR) 1.008, p = 0.656); however, we observed a prolonged progression-free survival (HR 1.565, p = 0.038) in pts with tumoral SMAD4 loss. This finding was confirmed in multivariate analyses (HR 1.790, p = 0.040), but only for gemcitabine-treated pts. In contrast to previous studies in resectable PC, loss of SMAD4 expression was not associated with a negative outcome in patients with advanced PC receiving systemic chemotherapy.

Molecular Events in the Natural History of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest epithelial malignancies. Improvements in our understanding of PDAC carcinogenesis will hopefully improve its detection, management, and outcomes, as has been achieved with other malignancies. Here we review the literature on the natural history of PDAC, including its cell of origin, the initiating somatic mutational events, pathways deranged in the mature tumor, its biological heterogeneity, and the relationship of the primary tumor with metastases. We also suggest areas for further research and highlight translatable findings that are beginning to make clinical inroads.