KRAS mutation status is not predictive for objective response to anti-EGFR treatment with erlotinib in patients with advanced pancreatic cancer

Recent Anti-KRASG12D Therapies: A "Possible Impossibility" for Pancreatic Ductal Adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer, able to thrive in a challenging tumor microenvironment. Current standard therapies, including surgery, radiation, chemotherapy, and chemoradiation, have shown a dismal survival prognosis, resulting in less than a year of life in the metastatic setting. Methods: The pressing need to find better therapeutic methods brought about the discovery of new targeted therapies against the infamous KRAS mutations, the major oncological drivers of PDAC. Results: The most common KRAS mutation is KRASG12D, which causes a conformational change in the protein that constitutively activates downstream signaling pathways driving cancer hallmarks. Novel anti-KRASG12D therapies have been developed for solid-organ tumors, including small compounds, pan-RAS inhibitors, protease inhibitors, chimeric T cell receptors, and therapeutic vaccines. Conclusions: This comprehensive review summarizes current knowledge on the biology of KRAS-driven PDAC, the latest therapeutic options that have been experimentally validated, and developments in ongoing clinical trials.

New Therapeutic Targets in RAS Wild-type Pancreatic Cancer

OPINION STATEMENT

The landscape of treatment of advanced PDAC is witnessing significant changes. This is in part due to the advent of molecular profiling, which has highlighted molecularly-distinct subsets of pts, especially those with KRAS wild-type disease. We now know that these pts harbor genomic alterations that not only serve as molecular drivers but also pose as therapeutically relevant markers. In the absence of strong evidence to support the use of targeted therapy in the front-line setting, we continue to offer chemotherapy for treatment-naïve pts. However, an argument can be made for the front-line use of targeted therapy in pts who are not fit for chemotherapy or who are not interested in it. The challenge is ensuring that molecular profiling is done in a timely fashion to prevent significant delays in therapy. In our practice, we offer molecular testing to all pts with a new diagnosis of advanced PDAC. We prefer the utility of targeted therapy in the second line and beyond for pts who have an actionable target, over the use of further chemotherapy, as targeted therapy appears to confer deep and durable responses and longer survival. For pts with MSI-H or MMRd disease, the use of immunotherapy is indicated, although it has to be noted that MSI-H/MMRd PDAC performed worse that other MSI-H/MMRd cancers treated with immunotherapy. Therefore, in the presence of MSI-H/MMRd and an additional actionable target, we prefer treating with targeted therapy and reserving immunotherapy for later lines. Pt preference has to be taken into consideration at all times though.

RAS signaling in carcinogenesis, cancer therapy and resistance mechanisms

Variants in the RAS family (HRAS, NRAS and KRAS) are among the most common mutations found in cancer. About 19% patients with cancer harbor RAS mutations, which are typically associated with poor clinical outcomes. Over the past four decades, KRAS has long been considered an undruggable target due to the absence of suitable small-molecule binding sites within its mutant isoforms. However, recent advancements in drug design have made RAS-targeting therapies viable, particularly with the approval of direct KRASG12C inhibitors, such as sotorasib and adagrasib, for treating non-small cell lung cancer (NSCLC) with KRASG12C mutations. Other KRAS-mutant inhibitors targeting KRASG12D are currently being developed for use in the clinic, particularly for treating highly refractory malignancies like pancreatic cancer. Herein, we provide an overview of RAS signaling, further detailing the roles of the RAS signaling pathway in carcinogenesis. This includes a summary of RAS mutations in human cancers and an emphasis on therapeutic approaches, as well as de novo, acquired, and adaptive resistance in various malignancies.

Duodenal Fluid Analysis as a Rewarding Approach to Detect Low-Abundance Mutations in Biliopancreatic Cancers

Diagnosis of biliopancreatic cancers by the available serum tumor markers, imaging, and histopathological tissue specimen examination remains a challenge. Circulating cell-free DNA derived from matched pairs of secretin-stimulated duodenal fluid (DF) and plasma from 10 patients with biliopancreatic diseases and 8 control subjects was analyzed using AmpliSeq™ HD technology for Ion Torrent Next-Generation Sequencing to evaluate the potential of liquid biopsy with DF in biliopancreatic cancers. The median cfDNA concentration was greater in DF-derived than in plasma-derived samples. A total of 13 variants were detected: 11 vs. 1 were exclusive for DF relative to the plasma source, and 1 was shared between the two body fluids. According to the four-tier systems, 10 clinical tier-I-II (76.9%), 1 tier-III (7.7%), and 2 tier-IV (15.4%) variants were identified. Notably, the 11 tier-I-III variants were exclusively found in DF-derived cfDNA from five patients with biliopancreatic cancers, and were detected in seven genes (KRAS, TP53, BRAF, CDKN2A, RNF43, GNAS, and PIK3CA); 82% of the tier-I-III variants had a low abundance, with a VAF < 6%. The mutational profiling of DF seems to be a reliable and promising tool for identifying cancer-associated alterations in malignant cancers of the biliopancreatic tract.

KRAS Mutation Subtypes and Their Association with Other Driver Mutations in Oncogenic Pathways

The KRAS mutation stands out as one of the most influential oncogenic mutations, which directly regulates the hallmark features of cancer and interacts with other cancer-causing driver mutations. However, there remains a lack of precise information on their cooccurrence with mutated variants of KRAS and any correlations between KRAS and other driver mutations. To enquire about this issue, we delved into cBioPortal, TCGA, UALCAN, and Uniport studies. We aimed to unravel the complexity of KRAS and its relationships with other driver mutations. We noticed that G12D and G12V are the prevalent mutated variants of KRAS and coexist with the TP53 mutation in PAAD and CRAD, while G12C and G12V coexist with LUAD. We also noticed similar observations in the case of PIK3CA and APC mutations in CRAD. At the transcript level, a positive correlation exists between KRAS and PIK3CA and between APC and KRAS in CRAD. The existence of the co-mutation of KRAS and other driver mutations could influence the signaling pathway in the neoplastic transformation. Moreover, it has immense prognostic and predictive implications, which could help in better therapeutic management to treat cancer.

Clinical practice guidelines for molecular tumor markers, 2nd edition review part 1

With advances in gene and protein analysis technologies, many target molecules that may be useful in cancer diagnosis have been reported. Therefore, the "Tumor Marker Study Group" was established in 1981 with the aim of "discovering clinically" useful molecules. Later, the name was changed to "Japanese Society for Molecular Tumor Marker Research" in 2000 in response to the remarkable progress in gene-related research. Currently, the world of cancer treatment is shifting from the era of representative tumor markers of each cancer type used for tumor diagnosis and treatment evaluation to the study of companion markers for molecular-targeted therapeutics that target cancer cells. Therefore, the first edition of the Molecular Tumor Marker Guidelines, which summarizes tumor markers and companion markers in each cancer type, was published in 2016. After publication of the first edition, the gene panel testing using next-generation sequencing became available in Japan in June 2019 for insured patients. In addition, immune checkpoint inhibitors have been indicated for a wide range of cancer types. Therefore, the 2nd edition of the Molecular Tumor Marker Guidelines was published in September 2021 to address the need to revise the guidelines. Here, we present an English version of the review (Part 1) of the Molecular Tumor Marker Guidelines, Second Edition.

Ultrasensitive and High-Resolution Protein Spatially Decoding Framework for Tumor Extracellular Vesicles

Proteins localized on the surface or within the lumen of tumor-derived extracellular vesicles (EVs) play distinct roles in cancer progression. However, quantifying both populations of proteins within EVs has been hampered due to the limited sensitivity of the existing protein detection methods and inefficient EV isolation techniques. In this study, the eSimoa framework, an innovative approach enabling spatial decoding of EV protein biomarkers with unmatched sensitivity and specificity is presented. Using the luminal eSimoa pipeline, the absolute concentration of luminal RAS or KRASG12D proteins is released and measured, uncovering their prevalence in pancreatic tumor-derived EVs. The pulldown eSimoa pipeline measured absolute protein concentrations from low-abundance EV subpopulations. The eSimoa assays detected EVs in both PBS and plasma samples, confirming their applicability across diverse clinical sample types. Overall, the eSimoa framework offers a valuable tool to (1) detect EVs at concentrations as low as 105 EV mL-1 in plasma, (2) quantify absolute EV protein concentrations as low as fM, and (3) decode the spatial distribution of EV proteins. This study highlights the potential of eSimoa in identifying disease-specific EV protein biomarkers in clinical samples with minimal pre-purification, thereby driving advancements in clinical translation.

Poor-prognosis molecular subtypes in adenocarcinomas of pancreato-biliary and gynecological origin: A systematic review

Pancreato-biliary and gynecological adenocarcinomas need better tools to predict clinical outcome. Potential prognostic mesenchymal(-like) transcriptome-based subtypes have been identified in these cancers. In this systematic review, we include studies into molecular subtyping and summarize biological and clinical features of the subtypes within and across sites of origin, searching for suggestions to improve classification and prognostication. PubMed and Embase were searched for original research articles describing potential mesenchymal(-like) mRNA-based subtypes in pancreato-biliary or gynecological adenocarcinomas. Studies limited to supervised clustering were excluded. Fourty-four studies, discussing cholangiocarcinomas, gallbladder, ampullary, pancreatic, ovarian, and endometrial adenocarcinomas were included. There was overlap in molecular and clinical features in mesenchymal(-like) subtypes across all adenocarcinomas. Approaches including microdissection were more likely to identify prognosis-associating subtypes. To conclude, molecular subtypes in pancreato-biliary and gynecological adenocarcinomas share biological and clinical characteristics. Furthermore, separation of stromal and epithelial signals should be applied in future studies into biliary and gynecological adenocarcinomas.

Prognostic value of KRAS subtype in patients with PDAC undergoing radical resection

Objective

To explore the frequency distribution of KRAS mutant subtypes in patients with resectable PDAC in China and then evaluate the prognostic value of different KRAS subtypes in patients with PDAC undergoing radical resection.

Methods

The clinicopathological data and gene test reports of 227 patients undergoing PDAC radical surgery at Hunan Provincial People's Hospital from 1 January 2016 to 1 January 1 2020 were retrospectively evaluated. There were 118 men (52%) and 109 women (48%). The mean age was 58.8 ± 10.3 years. After univariate analysis of the clinicopathological factors (sex, age, presence or absence of underlying disease, location of the primary tumour, tumour TNM stage, T stage, N stage, presence or absence of vascular invasion, presence or absence of nerve invasion, surgical margin, KRAS mutation subtype), variables with P < 0.1 were included in the multivariate Cox regression model analysis, and the log-rank sum test and Kaplan-Meier curves were used to assess the correlation of the KRAS mutation subtype with the overall survival time.

Results

KRAS mutations were detected in 184 of 227 patients (81.1%) (G12D: 66; G12V: 65; G12R: 27; Q61:26) and were not detected in 43 patients (18.9%). KRAS mutations were associated with tumour differentiation (P = 0.001), TNM stage (P = 0.013), and T stage (P < 0.001). Multivariate Cox regression model analysis showed that N stage, surgical margin, tumour differentiation, and KRAS-G12D mutation were independent prognostic factors for DFS and OS. Patients with the KRAS-G12D subtype had shorter OS with a median OS of 12 months (HR: 0.55, CI: 0.39-0.77, P < 0.001), and patients with KRAS wild-type had longer OS with a median OS of 19 months (HR: 0.57, CI: 0.42-0.76, P < 0.001).

Conclusion

KRAS wild-type individuals are more prevalent in the Chinese population than in European or American populations. Patients undergoing surgery had a reduced percentage of tumors with KRAS-G12D. When determining the prognosis of individuals with radically resected PDAC, reference markers for KRAS mutation subtypes can be employed.

KRAS G12D Mutation Subtype in Pancreatic Ductal Adenocarcinoma: Does It Influence Prognosis or Stage of Disease at Presentation?

Background: KRAS G12D mutation subtype is present in over 40% of pancreatic ductal adenocarcinoma (PDAC), one of the leading global causes of cancer death. This retrospective cohort study aims to investigate whether detection of the KRAS G12D mutation subtype in PDAC patients is a determinant of prognosis across all stages of disease. Methods: We reviewed the medical records of 231 patients presenting with PDAC at a large tertiary hospital, and compared survival using the Kaplan Meier, log-rank test and Cox proportional hazards regression model. Results: KRAS G12D mutation subtype was not significantly associated with poorer survival compared across the whole population of PDAC patients (p = 0.107; HR 1.293 95% CI (0.946-1.767)). However, KRAS G12D patients who were resectable had a shorter median survival time of 356 days compared to all other genotypes (median survival 810 days) (p = 0.019; HR 1.991 95% CI (1.121-3.537)). Conclusions: KRAS G12D patients who were resectable at diagnosis had shorter survival compared to all other PDAC patients. These data suggest that KRAS G12D may be a clinically useful prognostic biomarker of PDAC.

Therapeutic advances in metastatic pancreatic cancer: a focus on targeted therapies

Mortality from pancreatic ductal adenocarcinoma (PDAC) is increasing worldwide and effective new treatments are urgently needed. The current treatment of metastatic PDAC in fit patients is based on two chemotherapy combinations (FOLFIRINOX and gemcitabine plus nab-paclitaxel) which were validated more than 8 years ago. Although almost all treatments targeting specific molecular alterations have failed so far when administered to unselected patients, encouraging results were observed in the small subpopulations of patients with germline BRCA 1/2 mutations, and somatic gene fusions (neurotrophic tyrosine receptor kinase, Neuregulin 1, which are enriched in KRAS wild-type PDAC), KRAS G12C mutations, or microsatellite instability. While targeted tumor metabolism therapies and immunotherapy have been disappointing, they are still under investigation in combination with other drugs. Optimizing pharmacokinetics and adapting available chemotherapies based on molecular signatures are other promising avenues of research. This review evaluates the current expectations and limits of available treatments and analyses the existing trials. A permanent search for actionable vulnerabilities in PDAC tumor cells and microenvironments will probably result in a more personalized therapeutic approach, keeping in mind that supportive care must also play a major role if real clinical efficacy is to be achieved in these patients.

KRAS variant allele frequency, but not mutation positivity, associates with survival of patients with pancreatic cancer

KRAS mutation is a major driver of pancreatic carcinogenesis and will likely be a therapeutic target. Due to lack of sensitive assays for clinical samples of pancreatic cancer with low cellularity, KRAS mutations and their prognostic association have not been fully examined in large populations. In a multi-institutional cohort of 1162 pancreatic cancer patients with formalin-fixed paraffin-embedded tumor samples, we undertook droplet digital PCR (ddPCR) for KRAS codons 12/13/61. We examined detection rates of KRAS mutations by clinicopathological parameters and survival associations of KRAS mutation status. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) for disease-free survival (DFS) and overall survival (OS) were computed using the Cox regression model with adjustment for potential confounders. KRAS mutations were detected in 1139 (98%) patients. The detection rate did not differ by age of tissue blocks, tumor cellularity, or receipt of neoadjuvant chemotherapy. KRAS mutations were not associated with DFS or OS (multivariable HR comparing KRAS-mutant to KRAS-wild-type tumors, 1.04 [95% CI, 0.62-1.75] and 1.05 [95% CI, 0.60-1.84], respectively). Among KRAS-mutant tumors, KRAS variant allele frequency (VAF) was inversely associated with DFS and OS with HRs per 20% VAF increase of 1.27 (95% CI, 1.13-1.42; ptrend  <0.001) and 1.31 (95% CI, 1.16-1.48; ptrend  <0.001), respectively. In summary, ddPCR detected KRAS mutations in clinical specimens of pancreatic cancer with high sensitivity irrespective of parameters potentially affecting mutation detections. KRAS VAF, but not mutation positivity, was associated with survival of pancreatic cancer patients.

Emerging kinase inhibitors for the treatment of pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic cancer is one of the deadliest solid organ cancers. In the absence of specific warning symptoms pancreatic cancer is diagnosed notoriously late. Current systemic chemotherapy regimens extend survival by a mere few months. With the advances in genetic, proteomic, and immunological profiling there is strong rationale to test kinase inhibitors to improve outcome.

AREAS COVERED

This review article provides a comprehensive summary of approved treatments and past, present, and future developments of kinase inhibitors in pancreatic cancer. Emerging roles of protein kinase inhibitors are discussed in the context of the unique stroma, the lack of high-prevalence therapeutic targets and rapid emergence of acquired resistance, novel immuno-oncology kinase targets, and recent medicinal chemistry advances.

EXPERT OPINION

Due to the to-date frequent failure of protein kinase inhibitors indiscriminately administered to unselected pancreatic cancer patients, there is a shift toward the development of these agents in molecularly defined subgroups which are more likely to respond. The development of accurate biomarkers to select patients who are the best candidates based on a detailed understanding of mechanism of action, pro-survival roles, and mediation of resistance of targeted kinases will be critical for the future development of protein kinase inhibitors in this disease.

A special subtype: Revealing the potential intervention and great value of KRAS wildtype pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the predominant form of pancreatic cancer and has devastating consequences on affected families and society. Its dismal prognosis is attributed to poor specificity of symptoms during early stages. It is widely believed that PDAC patients with the wildtype (WT) KRAS gene benefit more from currently available treatments than those with KRAS mutations. The oncogenic genetic changes alternations generally found in KRAS wildtype PDAC are related to either the KRAS pathway or microsatellite instability/mismatch repair deficiency (MSI/dMMR), which enable the application of tailored treatments based on each patient's genetic characteristics. This review focuses on targeted therapies against alternative tumour mechanisms in KRAS WT PDAC.

Inhibitory Response to CK II Inhibitor Silmitasertib and CDKs Inhibitor Dinaciclib Is Related to Genetic Differences in Pancreatic Ductal Adenocarcinoma Cell Lines

Casein kinase II (CK2) and cyclin-dependent kinases (CDKs) frequently interact within multiple pathways in pancreatic ductal adenocarcinoma (PDAC). Application of CK2- and CDK-inhibitors have been considered as a therapeutic option, but are currently not part of routine chemotherapy regimens. We investigated ten PDAC cell lines exposed to increasing concentrations of silmitasertib and dinaciclib. Cell proliferation, metabolic activity, biomass, and apoptosis/necrosis were evaluated, and bioinformatic clustering was used to classify cell lines into sensitive groups based on their response to inhibitors. Furthermore, whole exome sequencing (WES) and RNA sequencing (RNA-Seq) was conducted to assess recurrent mutations and the expression profile of inhibitor targets and genes frequently mutated in PDAC, respectively. Dinaciclib and silmitasertib demonstrated pronounced and limited cell line specific effects in cell death induction, respectively. WES revealed no genomic variants causing changes in the primary structure of the corresponding inhibitor target proteins. RNA-Seq demonstrated that the expression of all inhibitor target genes was higher in the PDAC cell lines compared to non-neoplastic pancreatic tissue. The observed differences in PDAC cell line sensitivity to silmitasertib or dinaciclib did not depend on target gene expression or the identified gene variants. For the PDAC hotspot genes kirsten rat sarcoma virus (KRAS) and tumor protein p53 (TP53), three and eight variants were identified, respectively. In conclusion, both inhibitors demonstrated in vitro efficacy on the PDAC cell lines. However, aberrations and expression of inhibitor target genes did not appear to affect the efficacy of the corresponding inhibitors. In addition, specific aberrations in TP53 and KRAS affected the efficacy of both inhibitors.

The Inhibitory Response to PI3K/AKT Pathway Inhibitors MK-2206 and Buparlisib Is Related to Genetic Differences in Pancreatic Ductal Adenocarcinoma Cell Lines

The aberrant activation of the phosphoinositide 3-kinase (PI3K)/ protein kinase B (AKT) pathway is common in pancreatic ductal adenocarcinomas (PDAC). The application of inhibitors against PI3K and AKT has been considered as a therapeutic option. We investigated PDAC cell lines exposed to increasing concentrations of MK-2206 (an AKT1/2/3 inhibitor) and Buparlisib (a pan-PI3K inhibitor). Cell proliferation, metabolic activity, biomass, and apoptosis/necrosis were evaluated. Further, whole-exome sequencing (WES) and RNA sequencing (RNA-seq) were performed to analyze the recurrent aberrations and expression profiles of the inhibitor target genes and the genes frequently mutated in PDAC (Kirsten rat sarcoma virus (KRAS), Tumor protein p53 (TP53)). MK-2206 and Buparlisib demonstrated pronounced cytotoxic effects and limited cell-line-specific effects in cell death induction. WES revealed two sequence variants within the direct target genes (PIK3CA c.1143C > G in Colo357 and PIK3CD c.2480C > G in Capan-1), but a direct link to the Buparlisib response was not observed. RNA-seq demonstrated that the expression level of the inhibitor target genes did not affect the efficacy of the corresponding inhibitors. Moreover, increased resistance to MK-2206 was observed in the analyzed cell lines carrying a KRAS variant. Further, increased resistance to both inhibitors was observed in SU.86.86 carrying two TP53 missense variants. Additionally, the presence of the PIK3CA c.1143C > G in KRAS-variant-carrying cell lines was observed to correlate with increased sensitivity to Buparlisib. In conclusion, the present study reveals the distinct antitumor effects of PI3K/AKT pathway inhibitors against PDAC cell lines. Aberrations in specific target genes, as well as KRAS and TP53, individually or together, affect the efficacy of the two PI3K/AKT pathway inhibitors.

Four drug metabolism-related subgroups of pancreatic adenocarcinoma in prognosis, immune infiltration, and gene mutation

We aimed to screen the drug metabolism-related subgroups of pancreatic adenocarcinoma (PAAD) and to study the prognosis, clinical features, immune infiltration, and gene mutation differences of different subtypes in PAAD patients. All 181 cases of PAAD samples and clinical characteristics data were downloaded from The Cancer Genome Atlas (TCGA). After matching the drug metabolism-related genes downloaded from PMID 33202946 with the TCGA dataset, the drug metabolism-related genes were initially obtained. Besides, univariate Cox regression analysis was used to screen the drug metabolism genes related to the prognosis of PAAD. Moreover, the construction of the protein–protein interaction (PPI) network and gene ontology were performed. The four subgroups of PAAD obtained from unsupervised clustering analysis were systematically analyzed, including prognostic, GSVA, immune infiltration, and gene mutation analysis. A total of 83 drug metabolism genes related to the prognosis of PAAD were obtained and enriched in 16 pathways. The PPI network was composed of 248 relationship pairs. Four subgroups that can identify different subtypes of PPAD were obtained, and there were significant differences in survival and clinical characteristics, mutation types, and immune infiltration abundance between subgroups. A total of 17 different pathways among the four subgroups involved in cell cycle, response to stimulants such as drugs, and transmembrane transport. In this study, the four subgroups related to the drug metabolism of PAAD were comprehensively analyzed, and the important role of drug metabolism-related genes in the immune infiltration and prognosis of PAAD were emphasized.

Context Matters-Why We Need to Change From a One Size Fits all Approach to Made-to-Measure Therapies for Individual Patients With Pancreatic Cancer

Pancreatic cancer is one of the deadliest cancers and remains a major unsolved health problem. While pancreatic ductal adenocarcinoma (PDAC) is associated with driver mutations in only four major genes (KRAS, TP53, SMAD4, and CDKN2A), every tumor differs in its molecular landscape, histology, and prognosis. It is crucial to understand and consider these differences to be able to tailor treatment regimens specific to the vulnerabilities of the individual tumor to enhance patient outcome. This review focuses on the heterogeneity of pancreatic tumor cells and how in addition to genetic alterations, the subsequent dysregulation of multiple signaling cascades at various levels, epigenetic and metabolic factors contribute to the oncogenesis of PDAC and compensate for each other in driving cancer progression if one is tackled by a therapeutic approach. This implicates that besides the need for new combinatorial therapies for PDAC, a personalized approach for treating this highly complex cancer is required. A strategy that combines both a target-based and phenotypic approach to identify an effective treatment, like Reverse Clinical Engineering® using patient-derived organoids, is discussed as a promising way forward in the field of personalized medicine to tackle this deadly disease.

Oncogenic KRAS blockade therapy: renewed enthusiasm and persistent challenges

Across a broad range of human cancers, gain-of-function mutations in RAS genes (HRAS, NRAS, and KRAS) lead to constitutive activity of oncoproteins responsible for tumorigenesis and cancer progression. The targeting of RAS with drugs is challenging because RAS lacks classic and tractable drug binding sites. Over the past 30 years, this perception has led to the pursuit of indirect routes for targeting RAS expression, processing, upstream regulators, or downstream effectors. After the discovery that the KRAS-G12C variant contains a druggable pocket below the switch-II loop region, it has become possible to design irreversible covalent inhibitors for the variant with improved potency, selectivity and bioavailability. Two such inhibitors, sotorasib (AMG 510) and adagrasib (MRTX849), were recently evaluated in phase I-III trials for the treatment of non-small cell lung cancer with KRAS-G12C mutations, heralding a new era of precision oncology. In this review, we outline the mutations and functions of KRAS in human tumors and then analyze indirect and direct approaches to shut down the oncogenic KRAS network. Specifically, we discuss the mechanistic principles, clinical features, and strategies for overcoming primary or secondary resistance to KRAS-G12C blockade.

Clinical Effect of Driver Mutations of KRAS, CDKN2A/P16, TP53, and SMAD4 in Pancreatic Cancer: A Meta-Analysis

Objective: To evaluate the prognostic value of driver mutations in the KRAS, CDKN2A/P16, TP53, and SMAD4 genes in pancreatic cancer to aid in the design of therapeutic strategies. Search Strategy: A systematic search was conducted using PubMed, MEDLINE, Springer, and Cochrane library to identify eligible studies published between January 1990 and June 2018 that reported an association between driver mutations in these genes and survival data. Inclusion Criteria: Articles which passed the primary screen were further scrutinized for the presence of all the following items: (1) cohort studies or case-control studies, evaluating the relationship between driver mutations and cancer; (2) cancer diagnoses clearly proved; and (3) hazard ratios (HR) and 95% confidence intervals (CIs) were characterized by sufficient information. Data Extraction and Analysis: Selection of included articles, data extraction, and methodological quality assessments were, respectively, conducted by two authors. Results: The meta-analysis was composed of 17 studies on the P53, 8 on SMAD4, 7 on CDKN2A/P16, and 2 on KRAS, containing 3373 samples. Our pooled results demonstrated that the patients with overexpression of the P53 (HR = 1.249, 95% CI = 1.003-1.554, p = 0.047), SMAD4 (HR = 1.397, 95% CI = 1.015-1.922, p = 0.040), CDKN2A/P16 (HR = 0.916, 95% CI = 0.583-1.439, p = 0.704), and KRAS (HR = 1.68, 95% CI = 1.27-2.22, p < 0.001) mutations all had poorer overall survival. Conclusion: This systematic review and meta-analysis supports the use of driver mutations in the P53, SMAD4, and KRAS genes as prognostic markers for pancreatic cancer.

Treatment outcomes of erlotinib plus gemcitabine as late-line chemotherapy in unresectable pancreatic cancer

OBJECTIVE

With the introduction of modified FOLFIRINOX and gemcitabine plus nab-paclitaxel therapy for unresectable pancreatic cancer, erlotinib plus gemcitabine therapy is now occasionally used as late-line therapy. This study investigates outcomes of treatment with erlotinib plus gemcitabine for unresectable pancreatic cancer.

METHODS

We retrospectively analysed consecutive patients with unresectable pancreatic cancer treated with erlotinib plus gemcitabine as the third or later-line chemotherapy between March 2014 and December 2020 in our hospital.

RESULTS

A total of 56 patients were included (third line/fourth or later line = 42/14). All patients were previously treated with gemcitabine plus nab-paclitaxel and 45 patients were previously treated with modified FOLFIRINOX. The median progression-free survival (PFS) and overall survival (OS) were 1.6 and 4.6 months, respectively. The disease control rate was 21.4%. Performance status, modified Glasgow prognostic score and carcinoembryonic antigen level were independently associated with survival. Our prognostic model using these parameters could classify patients into good (n = 32) and poor (n = 24) prognostic groups. The median PFS and OS were longer in good than in poor prognostic group, but the difference in PFS was very small (PFS: 2.1 vs. 1.4 months, P = 0.01. OS: 6.8 vs. 2.4 months, P < 0.01). Interstitial pneumonia occurred in one patient (1.8%).

CONCLUSIONS

Benefits of erlotinib plus gemcitabine as late-line chemotherapy were limited, particularly with respect to PFS. Development of more effective third-line treatment options is desirable in the future.

KRAS, A Prime Mediator in Pancreatic Lipid Synthesis through Extra Mitochondrial Glutamine and Citrate Metabolism

Kirsten rat sarcoma viral oncogene homolog (KRAS)-driven pancreatic cancer is very lethal, with a five-year survival rate of <9%, irrespective of therapeutic advances. Different treatment modalities including chemotherapy, radiotherapy, and immunotherapy demonstrated only marginal efficacies because of pancreatic tumor specificities. Surgery at the early stage of the disease remains the only curative option, although only in 20% of patients with early stage disease. Clinical trials targeting the main oncogenic driver, KRAS, have largely been unsuccessful. Recently, global metabolic reprogramming has been identified in patients with pancreatic cancer and oncogenic KRAS mouse models. The newly reprogrammed metabolic pathways and oncometabolites affect the tumorigenic environment. The development of methods modulating metabolic reprogramming in pancreatic cancer cells might constitute a new approach to its therapy. In this review, we describe the major metabolic pathways providing acetyl-CoA and NADPH essential to sustain lipid synthesis and cell proliferation in pancreatic cancer cells.

Advances in Targeted Therapy and Immunotherapy for Pancreatic Cancer

Pancreatic cancer is a highly aggressive malignancy with an overall 5-year survival rate of <6% due to therapeutic resistance and late-stage diagnosis. These statistics have not changed despite 50 years of research and therapeutic development. Pancreatic cancer is predicted to become the second leading cause of cancer mortality by the year 2030. Currently, the treatment options for pancreatic cancer are limited. This disease is usually diagnosed at a late stage, which prevents curative surgical resection. Chemotherapy is the most frequently used approach for pancreatic cancer treatment and has limited effects. In many other cancer types, targeted therapy and immunotherapy have made great progress and have been shown to be very promising prospects; these treatments also provide hope for pancreatic cancer. The need for research on targeted therapy and immunotherapy is pressing due to the poor prognosis of pancreatic cancer, and in recent years, there have been some breakthroughs for targeted therapy and immunotherapy in pancreatic cancer. This review summarizes the current preclinical and clinical studies of targeted therapy and immunotherapy for pancreatic cancer and ends by describing the challenges and outlook.

KRAS mutation in pancreatic cancer

Pancreatic cancer is a recalcitrant cancer with one of the lowest 5-year survival rates. A hallmark of pancreatic cancer is the prevalence of oncogenic mutation in the KRAS gene. The KRAS oncogene plays a critical role in the initiation and maintenance of pancreatic tumors and its signaling network represents a major target for therapeutic intervention. A number of inhibitors have been developed against kinase effectors in various Ras signaling pathways. Their clinical activity, however, has been disappointing thus far. More recently, covalent inhibitors targeting the KRASG12C oncoprotein have been developed. These inhibitors showed promising activity in KRASG12C mutant pancreatic cancer in early clinical trials. This review will present an updated summary of our understanding of mutant KRAS function in pancreatic cancer and discuss therapeutic strategies that target oncogenic KRAS signaling in this disease.

Locally Advanced Pancreatic Ductal Adenocarcinoma: Challenges and Progress

Pancreatic ductal adenocarcinoma (PDAC) is one of the major causes of death in the Western world, and it is estimated to become the second leading cause of tumour-related mortality in the next 10 years. Among pancreatic cancers, ductal adenocarcinomas are by far the most common, characterised by a challenging diagnosis due to the lack of initial and pathognomonic clinical signs. In this scenario, non-metastatic locally advanced pancreatic cancer (LAPC) accounts for a large proportion of all new pancreatic ductal adenocarcinoma diagnoses. There is no consensus on a common definition of LAPC. Still, it usually includes tumours that are not resectable due to vascular involvement. As of today, treatment is limited, and the prognosis is very unfavourable. Curative-intent surgery remains the gold-standard even if often jeopardized by vascular involvement. Continuing progress in our understanding of LAPC genetics and immunology will permit the development of different treatments, targeted or combined, including radiation therapy, hadrontherapy, targeted immunotherapies or new chemotherapies. A multidisciplinary approach combining various fields of expertise is essential in aiming to limit disease progression as well as patient outcome. Using a narrative literature review approach, the manuscript explores the most up-to-date knowledge concerning locally advanced pancreatic ductal adenocarcinoma management.

Targeting Mutant KRAS in Pancreatic Cancer: Futile or Promising?

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal cancers with a dismal prognosis for the patient. This is due to limited diagnostic options for the early detection of the disease as well as its rather aggressive nature. Despite major advances in oncologic research in general, the treatment options in the clinic for PDAC have only undergone minor changes in the last decades. One major treatment advance would be the successful targeting of the oncogenic driver KRASmut. In the past, the indirect targeting of KRAS has been exploited, e. g., via upstream inhibition of receptor tyrosine kinases or via downstream MEK or PI3K inhibition. However, the experience gained from clinical trials and from the clinic itself in the treatment of KRASmut cancer entities has dampened the initial euphoria. Lately, with the development of KRASG12C-specific inhibitors, not only the direct but also the indirect targeting of KRASmut has gained momentum again. Though preclinical studies and preliminary early clinical studies of monotherapies have shown promising results, they have been overshadowed by the swift development of resistances resulting in inconsistent responses in patient cohorts. Currently, several different combination therapies for KRASmut cancer are being explored. If they hold the promise they have made in preclinical studies, they might also be suitable treatment options for patients suffering from PDAC.

Role of oncogenic KRAS in the diagnosis, prognosis and treatment of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is predicted to be the second most common cause of death within the next 10 years. The prognosis for this disease is poor despite diagnostic progress and new chemotherapeutic regimens. The oncogenic KRAS mutation is the major event in pancreatic cancer; it confers permanent activation of the KRAS protein, which acts as a molecular switch to activate various intracellular signalling pathways and transcription factors inducing cell proliferation, migration, transformation and survival. Several laboratory methods have been developed to detect KRAS mutations in biological samples, including digital droplet PCR (which displays high sensitivity). Clinical studies have revealed that a KRAS mutation assay in fine-needle aspiration material combined with cytopathology increases the sensitivity, accuracy and negative predictive value of cytopathology for a positive diagnosis of pancreatic cancer. In addition, the presence of KRAS mutations in serum and plasma (liquid biopsies) correlates with a worse prognosis. The presence of mutated KRAS can also have therapeutic implications, whether at the gene level per se, during its post-translational maturation, interaction with nucleotides and after activation of the various oncogenic signals. Further pharmacokinetic and toxicological studies on new molecules are required, especially small synthetic molecules, before they can be used in the therapeutic arsenal for pancreatic ductal adenocarcinoma.

Establishment of an organoid bank of biliary tract and pancreatic cancers and its application for personalized therapy and future treatment

Biliary tract cancers and pancreatic cancers are aggressive malignancies that are difficult to diagnose early and have a poor prognosis. Patients with inoperable biliary tract and pancreatic cancers generally receive chemotherapy regimens including gemcitabine. However, the effects of these drugs are limited, and the 5-year survival rates of patients are very low. The newly developed three-dimensional culture system known as "organoid culture" allows long-term expansion of stem cells into cyst-like structures (organoids) with properties resembling those of the original tissues. We and other groups have successfully established long-term in vitro cultures of organoids derived from biliary tract and pancreatic cancers. Organoids derived from biliary tract and pancreatic cancers closely recapitulate the properties of the original tumors including genetic alterations, gene expression profiles, and histopathological structures. These patient-derived cancer organoids can be applied for drug sensitivity testing, drug screening, epigenetic therapy, and differentiation-inducing therapy to identify therapeutic agents optimal for each patient. We intend to further establish organoids derived from various cancer cases and construct an organoid bank of biliary tract and pancreatic cancers. These powerful in vitro preclinical models of refractory cancers may bridge the gap between basic research and clinical trials and allow personalized therapy for patients.

A Comparative Analysis of Individual RAS Mutations in Cancer Biology

In human cells, three closely related RAS genes, termed HRAS, KRAS, and NRAS, encode four highly homologous proteins. RAS proteins are small GTPases involved in a broad spectrum of key molecular and cellular activities, including proliferation and survival among others. Gain-of-function missense mutations, mostly located at codons 12, 13, and 61, constitutively activate RAS proteins and can be detected in various types of human cancers. KRAS is the most frequently mutated, followed by NRAS and HRAS. However, each isoform exhibits distinctive mutation frequency at each codon, supporting the hypothesis that different RAS mutants may lead to distinct biologic manifestations. This review is focused on the differences in signaling and phenotype, as well as on transcriptomics, proteomics, and metabolomics profiles related to individual RAS-mutated variants. Additionally, association of these mutants with particular targeted outcomes and rare mutations at additional RAS codons are discussed.

Pancreatic ductal adenocarcinoma: biological hallmarks, current status, and future perspectives of combined modality treatment approaches

Pancreatic ductal adenocarcinoma (PDAC) is a highly devastating disease with poor prognosis and rising incidence. Late detection and a particularly aggressive biology are the major challenges which determine therapeutic failure. In this review, we present the current status and the recent advances in PDAC treatment together with the biological and immunological hallmarks of this cancer entity. On this basis, we discuss new concepts combining distinct treatment modalities in order to improve therapeutic efficacy and clinical outcome - with a specific focus on protocols involving radio(chemo)therapeutic approaches.

A Phase II Randomized Trial of Panitumumab, Erlotinib, and Gemcitabine Versus Erlotinib and Gemcitabine in Patients with Untreated, Metastatic Pancreatic Adenocarcinoma: North Central Cancer Treatment Group Trial N064B (Alliance)

LESSONS LEARNED

Dual epidermal growth factor receptor (EGFR)-directed therapy with erlotinib and panitumumab in combination with gemcitabine was superior to gemcitabine and erlotinib, but the clinical relevance is uncertain given the limited role of gemcitabine monotherapy.A significantly longer overall survival was observed in patients receiving the dual EGFR-directed therapy.The dual EGFR-directed therapy resulted in increased toxicity.

BACKGROUND

Gemcitabine is active in patients with advanced pancreatic adenocarcinoma. The combination of erlotinib, an oral epidermal growth factor receptor (EGFR) inhibitor, and gemcitabine was shown to modestly prolong overall survival when compared with gemcitabine alone. The North Central Cancer Treatment Group (now part of Alliance for Clinical Trials in Oncology) trial N064B compared gemcitabine plus erlotinib versus gemcitabine plus combined EGFR inhibition with erlotinib and panitumumab.

METHODS

Eligible patients with metastatic adenocarcinoma of the pancreas were randomized to either gemcitabine 1,000 mg/m2 on days 1, 8, and 15 of a 28-day cycle with erlotinib 100 mg p.o. daily (Arm A) or the same combination with the addition of panitumumab 4 mg/kg on days 1 and 15 of a 28-day cycle (Arm B). The primary endpoint of the trial was overall survival. Secondary endpoints included progression-free survival, the confirmed response rate, and toxicity. Comparison between arms for the primary endpoint was done with a one-sided log-rank test, and a p value less than .20 was considered statistically significant. Response rate comparison was done with Fisher's exact test. All other reported p values are two-sided.

RESULTS

A total of 92 patients were randomized, 46 to each arm. The median overall survival was 4.2 months in Arm A and 8.3 months in Arm B (hazard ratio, 0.817; 95% confidence interval [CI], 0.530-1.260; p = .1792). The progression-free survival was 2.0 months in Arm A and 3.6 months in Arm B (hazard ratio, 0.843; 95% CI, 0.555-1.280; p = .4190). A partial confirmed response was seen in 8.7% of patients on Arm A and 6.5% on Arm B (p = .9999). No patients had a complete response. Grade 3 and higher nonhematologic toxicities were more common in patients on Arm B compared with those on Arm A (82.6% vs. 52.2%; p = .0018).

CONCLUSION

Dual EGFR-directed therapy resulted in a significant prolongation of overall survival in patients with advanced adenocarcinoma of the pancreas but was associated with substantially increased toxicities. Dual EGFR-directed therapy in combination with gemcitabine alone cannot be recommended for further study, as single-agent gemcitabine is no longer considered an appropriate therapy for otherwise fit patients with metastatic pancreatic cancer.

Combating pancreatic cancer with PI3K pathway inhibitors in the era of personalised medicine

Pancreatic ductal adenocarcinoma (PDAC) is among the most deadly solid tumours. This is due to a generally late-stage diagnosis of a primarily treatment-refractory disease. Several large-scale sequencing and mass spectrometry approaches have identified key drivers of this disease and in doing so highlighted the vast heterogeneity of lower frequency mutations that make clinical trials of targeted agents in unselected patients increasingly futile. There is a clear need for improved biomarkers to guide effective targeted therapies, with biomarker-driven clinical trials for personalised medicine becoming increasingly common in several cancers. Interestingly, many of the aberrant signalling pathways in PDAC rely on downstream signal transduction through the mitogen-activated protein kinase and phosphoinositide 3-kinase (PI3K) pathways, which has led to the development of several approaches to target these key regulators, primarily as combination therapies. The following review discusses the trend of PDAC therapy towards molecular subtyping for biomarker-driven personalised therapies, highlighting the key pathways under investigation and their relationship to the PI3K pathway.

Randomized, phase I/II study of gemcitabine plus IGF-1R antagonist (MK-0646) versus gemcitabine plus erlotinib with and without MK-0646 for advanced pancreatic adenocarcinoma

BACKGROUND

Binding of insulin-like growth factor-I (IGF-1) to its receptor (IGF-1R) initiates downstream signals that activate PI3K/Akt/mTOR and MEK/Erk pathways, which stimulate cancer cell proliferation and induce drug resistance. Cross talk between IGF-1R and epidermal growth factor receptor (EGFR) mediates resistance to anti-EGFR agents. We studied safety, tolerability, and outcomes of MK-0646, IGF-1 monoclonal antibody, in combination with gemcitabine (G) ± erlotinib (E) in metastatic pancreatic cancer.

METHODS

Our study included a phase I dose escalation and phase II randomization and expansion cohorts. A 3 + 3 dose escalation protocol was used to determine MK-0646 maximum tolerable dose (MTD) in combination with G ± E standard doses. For phase II, patients were randomized to arm A (G + MK), arm B (G + MK + E), or arm C (G + E). Primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS), disease control rate, toxicity, and correlation between OS and IGF-1 in patients treated with MK-0646.

RESULTS

MK-0646 MTD was 10 mg/kg in combination with G and 5 mg/kg in combination with G + E. In randomization cohort, 15 patients were treated in each arm. Disease control rates were 50, 60, and 40% respectively. PFS was not different between the three arms. OS was significantly different between arm A (10.4 months) and C (5.7 months) (P = 0.02). However, addition of erlotinib in arm B yielded no OS benefit compared to arm A (P = 0.6). Plasma and tissue IGF-1 levels did not correlate with OS (P = 0.64, 0.87). Grade 3-4 toxicity during phase II cohorts were neutropenia (10/arm A, 14/arm B, 5/arm C), leukopenia (5/A, 5/B, 7/C), thrombocytopenia (8/A, 9/B, 2/C), hyponatremia (1/A, 3/B), and hyperglycemia (8/A, 1/B).

CONCLUSIONS

MK-0646 was tolerable in combination with G and associated with improvement in OS but not PFS as compared with G + E. Tissue and serum IGF-1 did not correlate with clinical outcome.

TRIAL REGISTRATION

This trial is registered in ClinicalTrial.gov under the Identifier NCT00769483 and registration date was October 9, 2008.

NRG1 Fusions in KRAS Wild-Type Pancreatic Cancer

We used whole-genome and transcriptome sequencing to identify clinically actionable genomic alterations in young adults with pancreatic ductal adenocarcinoma (PDAC). Molecular characterization of 17 patients with PDAC enrolled in a precision oncology program revealed gene fusions amenable to pharmacologic inhibition by small-molecule tyrosine kinase inhibitors in all patients with KRAS wild-type (KRAS^WT) tumors (4 of 17). These alterations included recurrent NRG1 rearrangements predicted to drive PDAC development through aberrant ERBB receptor-mediated signaling, and pharmacologic ERBB inhibition resulted in clinical improvement and remission of liver metastases in 2 patients with NRG1-rearranged tumors that had proved resistant to standard treatment. Our findings demonstrate that systematic screening of KRAS^WT tumors for oncogenic fusion genes will substantially improve the therapeutic prospects for a sizeable fraction of patients with PDAC.Significance: Advanced PDAC is a malignancy with few treatment options that lacks molecular mechanism-based therapies. Our study uncovers recurrent gene rearrangements such as NRG1 fusions as disease-driving events in KRAS^wt tumors, thereby providing novel insights into oncogenic signaling and new therapeutic options in this entity. Cancer Discov; 8(9); 1087-95. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 1047.

Biomarker-Based Therapy in Pancreatic Ductal Adenocarcinoma: An Emerging Reality?

Over the last decade, many of the major solid organ cancers have seen improvements in survival due to development of novel therapeutics and corresponding biomarkers that predict treatment efficacy or resistance. In contrast, favorable outcomes remain challenging in pancreatic ductal adenocarcinoma (PDAC), in part related to the lack of validated biomarkers for patient and treatment selection and thus optimal clinical decision-making. Increasingly, however, therapeutic development for PDAC is accompanied by bioassays to evaluate response and to study mechanism of actions with a corresponding increase in the number of trials in mid to late stage with integrated biomarkers. In addition, blood-based biomarkers that provide a measure of disease activity and allow for minimally invasive tumor analyses are emerging, including circulating tumor DNA, exosomes, and circulating tumor cells. In this article, we review potential biomarkers for currently approved therapies as well as emerging biomarkers for therapeutics under development. Clin Cancer Res; 24(10); 2241-50. ©2017 AACR.

Switch in KRAS mutational status during an unusual course of disease in a patient with advanced pancreatic adenocarcinoma: implications for translational research

BACKGROUND

Despite the introduction of novel effective treatment regimens like gemcitabine plus nab-paclitaxel and FOLFIRINOX, pancreatic ductal adenocarcinoma (PDAC) remains one of the most aggressive epithelial tumors. Among the genetic alterations frequently found in PDAC, mutations in the KRAS gene might play a prognostic role regarding overall survival and may also have the potential to predict the efficacy of anti-EGFR treatment.

CASE PRESENTATION

We report the clinical case of a 69 year old Caucasian female that was diagnosed with histologically confirmed locally advanced PDAC with lymph node involvement in August 2010. At the time of first diagnosis, tumor tissue obtained from an open regional lymph node biopsy showed a poorly differentiated adenocarcinoma with a wild type sequence within exon 2 (codon 12/13) of the KRAS gene. The patient initially received single-agent gemcitabine and a subsequent 5-FU-based chemoradiotherapy with a sequential maintenance chemotherapy with oral capecitabine resulting in a long term disease control. Local disease progression occurred in May 2014 and the patient underwent pancreaticoduodenectomy in September 2014. A novel KRAS gene mutation (c.35G > T, p.G12 V) in exon 2 (codon 12) was detected within the surgical specimen. As of January 2016 the patient is still alive and without evidence of the underlying disease.

CONCLUSIONS

Specifically in the context of clinical trials and translational research in PDAC a re-assessment of molecular biomarkers, i. e. KRAS, at defined time points (e. g. relapse, disease progression, unusual clinical course) may be indicated in order to detect a potential switch in biomarker status during the course of disease.

KRAS, TP53, CDKN2A, SMAD4, BRCA1, and BRCA2 Mutations in Pancreatic Cancer

Pancreatic cancer is a disease that has a very high fatality rate and one of the highest mortality ratios among all major cancers, remaining the fourth leading cause of cancer-related deaths in developed countries. The major treatment of pancreatic cancer is surgery; however, only 15–20% of patients are candidates for it at the diagnosis of disease. On the other hand, survival in patients, who undergo surgery, is less than 30%. In most cancers, genome stability is disturbed and pancreatic cancer is not the exception. Approximately 97% of pancreatic cancers have gene derangements, defined by point mutations, amplifications, deletions, translocations, and inversions. This review describes the most frequent genetic alterations found in pancreatic cancer.

Personalized medicine in sporadic pancreatic cancer without homologous recombination-deficiency: are we any closer?

Pancreatic adenocarcinoma is the fourth leading cause of cancer related death in the United States. Most patients are diagnosed at a late stage and despite recent advances in chemotherapeutic approaches, outcomes are poor. With the introduction of combination chemotherapy, novel biomarkers are clearly needed to identify subsets of patients likely to benefit from these therapies. Advances in our understanding of the molecular drivers of pancreatic cancer offer the hope of personalized therapy that may benefit our patients. In this review, we summarize the current knowledge about the biology of pancreatic cancer and its implication for treatment. We discuss recent advances in targeted therapies and the role of potential biomarkers in predicting response to established therapies. We also review novel therapeutic approaches that may be able to fulfill the promise of personalized therapy for pancreatic cancer.

Prognostic value of circulating tumour DNA in patients undergoing curative resection for pancreatic cancer

Background:

Pancreatic ductal adenocarcinoma (PDAC) is frequently diagnosed at an advanced stage, leading to a poor prognosis. Therefore, interest in the development of non-invasive biomarkers for prognostic prediction has grown rapidly. Here, we assessed the clinical implications of v-Ki-ras2 kirsten rat sarcoma viral oncogene homolog (KRAS)-mutated circulating tumour DNA (ctDNA) as a useful surrogate biomarker in patients with resectable PDAC.

Methods:

We used droplet digital polymerase chain reaction to detect rare mutant tumour-derived KRAS genes in plasma cell-free DNA (cfDNA) as ctDNA. Samples were collected from 105 patients who underwent pancreatoduodenectomy for PDAC at a single institution. Overall survival (OS) was analysed according to the presence of ctDNA.

Results:

Among the 105 cases, ctDNA was detected in 33 (31%) plasma samples. The median OS durations were 13.6 months for patients with ctDNA (ctDNA+) and 27.6 months for patients without ctDNA. Patients who were ctDNA+ had a significantly poorer prognosis with respect to OS (P<0.0001).

Conclusions:

Our findings suggested that the presence of ctDNA in plasma samples could be an important and powerful predictor of poor survival in patients with PDAC. Accordingly, ctDNA detection might be a promising approach with respect to PDAC treatment.

K-Ras mutation detection in liquid biopsy and tumor tissue as prognostic biomarker in patients with pancreatic cancer: a systematic review with meta-analysis

K-Ras gene mutations have been found in most pancreatic cancers; however, conflicting data on the prognostic value of K-Ras mutations in pancreatic cancer have been published. We conducted a meta-analysis to assess its prognostic significance. Literature searches of PubMed, EMBASE, Cochrane Library, Web of Science and Google Scholar were performed through December 2015 to identify publications exploring the association of K-Ras mutation with overall survival. Forty eligible studies involving 3427 patients with pancreatic cancer were included in the present meta-analysis. Our analysis showed a hazard ratio (HR) of negative association with survival of 1.61 [95 % confidence interval (CI) 1.36-1.90; p < 0.01] in K-Ras mutant pancreatic cancer patients. In subgroup analyses, K-Ras mutations detected in tumor tissues and in liquid biopsies had HRs of 1.37 (95 % CI 1.20-1.57; p < 0.01) and 3.16 (95 % CI 2.1-4.71; p < 0.01), respectively. In addition, the HR was higher when K-Ras mutations were detected in fresh frozen samples (HR = 2.01, 95 % CI 1.28-3.16, p = 0.002) than in formalin-fixed, paraffin-embedded (FFPE) samples (HR = 1.29, 95 % CI 1.12-1.49, p < 0.01). Though K-Ras alterations are more frequent among non-East Asian individuals than East Asian individuals, there were no significant differences in HRs of survival between the two ethnic subgroups. In conclusion, this meta-analysis suggests that K-Ras mutations are associated with a worse overall survival in pancreatic cancer patients, especially when mutations are detected in liquid biopsies or fresh frozen tumor tissue samples.

The role of exosomes in the pathogenesis of pancreatic ductal adenocarcinoma

Exosomes are small membrane bound vesicles secreted by cancer cells that have a cytosol rich in proteins and nucleic acids which are capable of modulating the phenotype of neighbouring cells which take them up. In this review we explore the mechanisms through which exosomes are able to impact on the pathogenesis of pancreatic ductal cancer through the modulation of tumour formation and development and exploitation of the tumour microenvironment to modulate both the adaptive and innate immune response. In addition we highlight the potential utility of exosomes not only as biomarkers of disease but also as tools to be used in the therapeutic armamentarium against this disease.

KRAS G12D Mutation Subtype Is A Prognostic Factor for Advanced Pancreatic Adenocarcinoma

OBJECTIVES

There is no molecular biomarker available in the clinical practice to assess the prognosis of advanced pancreatic carcinoma. This multicenter prospective study aimed to investigate the role of KRAS mutation subtypes within the primary tumor to determine the prognosis of advanced pancreatic cancer.

METHODS

The exon-2 KRAS mutation status was tested on endoscopic ultrasound-guided fine-needle aspiration biopsy material (primary tumor; restriction fragment-length polymorphism plus sequencing and TaqMan allelic discrimination) of patients with proven locally advanced and/or metastatic pancreatic ductal carcinoma. We used the Kaplan-Meier method, log-rank test, and Cox's model to evaluate the impact of KRAS status on the overall survival (OS), adjusting for age, stage of disease, clinical performance status, CA 19-9 levels, and treatment.

RESULTS

A total of 219 patients (men: 116; mean age: 67±9.4 years) were included: 147 harbored a codon-12 KRAS mutation (G12D: 73; G12V: 53; G12R: 21) and 72 had a wild-type KRAS. There was no difference in the OS between patients with a mutant KRAS (8 months; 95% confidence interval (95% CI): 8.7-12.3) and the wild-type (9 months; 95% CI: 8.7-12.8; hazard ratio (HR): 1.03; P=0.82). However, the patients with a G12D mutation had a significantly shorter OS (6 months; 95% CI: 6.4-9.7) compared with the other patients (OS: 9 months; 95% CI: 10-13; HR: 1.47; P=0.003; i.e., wild type: 9 months, G12V: 9 months, G12R: 14 months). Similar results were observed in the subgroup of 162 patients who received chemotherapy (HR: 1.66; P=0.0013; G12D (n=49): 8 months, wild type (n=56): 10 months, G12V (n=38): 10 months, G12R (n=19): 14 months). Multivariate analyses identified KRAS G12D as an independent predictor for worse prognosis within the entire series (HR: 1.44; P=0.01) and in the subgroup of patients that received chemotherapy (HR: 1.84; P=0.02).

CONCLUSIONS

The KRAS G12D mutation subtype is an independent prognostic marker for advanced pancreatic ductal carcinoma. Codon and amino-acid-specific mutations of KRAS should be considered when evaluating the prognoses as well as in trials testing drugs that target RAS and downstream RAS pathways.

Prolonged complete response following gemcitabine-erlotinib combined therapy in advanced pancreatic cancer

Pancreatic cancer is one of the most lethal types of malignant solid tumor and is typically associated with a poor prognosis. The majority of patients are diagnosed with advanced-stage disease, therefore, the median survival period is <6 months. Recently, a number of basic research projects and clinical trials were undertaken with the aim of improving treatment outcomes in pancreatic cancer; however, only one agent, erlotinib, passed the clinical trials. Erlotinib is an inhibitor of epidermal growth factor receptor, which when overexpressed in cancer, promotes angiogenesis, cell proliferation and inhibits apoptosis. The US Food and Drug Administration and European Medicines Agency approved erlotinib in combination with gemcitabine for the first-line treatment of advanced pancreatic cancer. To the best of our knowledge, the current study is the first to report a case of pancreatic cancer treated with this regimen alone to achieve a complete response (CR). A 40-year-old male with a medical history of chronic pancreatitis and hypertension was diagnosed with medically inoperable adenocarcinoma of the pancreas. Following palliative surgery, the patient began palliative gemcitabine and erlotinib chemotherapy. After three months, this treatment strategy resulted in a CR, as determined by imaging studies. Therapy was discontinued after 14 months due to the development of peritoneal metastases and the patient was referred for treatment with the folinic acid, 5-fluorouracil, irinotecan and oxaliplatin regimen. A CR is rarely reported in pancreatic cancer, however, a treatment strategy of gemcitabine and erlotinib may induce rapid regression of advanced-stage disease.

Current controversies in the stage-specific multidisciplinary management of pancreatic cancer

Encouraging therapeutic approaches and treatment regimens for patients with both localized and metastatic pancreatic cancer have emerged over the last 5 years. However, these new strategies have brought important challenges and controversy. Clinical staging criteria are constantly evolving. No system has been uniformly adopted, limiting our understanding of the role of both pancreatectomy and neoadjuvant therapies for localized disease. The role of radiation therapy for the treatment of both resectable and unresectable pancreatic cancer remains unclear despite multiple prospective studies. Although two new systemic chemotherapy regimens have essentially transformed the care of many patients with metastatic cancer, criteria to guide their use in the general population have yet to be clearly established. Herein we provide an overview of these important controversies in the context of a broad update on the stage-specific management of patients with newly diagnosed pancreatic cancer.