Targeting KRAS: The Elephant in the Room of Epithelial Cancers

Biological and genetic characterization of a newly established human primary multidrug-resistant distal cholangiocarcinoma cell line, CBC3T-6

Distal cholangiocarcinoma is a rare and highly aggressive malignant tumor. The inherent tumor characteristics and growth pattern of cancer cells pose a challenge for diagnosis and treatment. Chemotherapy resistance leads to limited treatment options for patients with advanced cholangiocarcinoma. However, drug resistance studies in cholangiocarcinoma are often limited by the use of preclinical models that do not accurately replicate the essential features of the disease. In this study, we established and characterized a primary multidrug-resistant distal cholangiocarcinoma cell line, CBC3T-6. STR profiling indicated no evidence of cross-contamination. This cell line remains stable during long-term in vitro culture and is characterized by short doubling times and rapid subcutaneous tumor formation in mice. In addition, among the first-line anticancer drugs for cholangiocarcinoma, CBC3T-6 cells showed varying degrees of resistance to gemcitabine, oxaliplatin, cisplatin, and 5-FU. Whole exome sequencing analysis revealed that CBC3T-6 cells contained a variety of potentially pathogenic somatic cell mutations, such as TP53 and KRAS mutations. ABCB1 mutation as a possible therapeutic target for multidrug resistance. In conclusion, CBC3T-6 cells can be used as a useful tool to study the mechanism of cholangiocarcinoma and develop new therapeutic strategies for multidrug resistance.

Design and development of dual targeting CAR protein for the development of CAR T-cell therapy against KRAS mutated pancreatic ductal adenocarcinoma using computational approaches

Mutant KRAS promotes the proliferation, metastasis, and aggressiveness of various cancers including pancreatic ductal adenocarcinoma (PDAC), non-small cell lung cancer (NSCLC), and colorectal adenocarcinoma (CRC) respectively. Mutant KRAS therapeutics are limited, while Sotorasib and Adagrasib were the only FDA-approved drugs for the treatment of KRASG12C mutated NSCLC. Chimeric antigen receptor (CAR) T-cell therapy has been emerged as an effective strategy against hematological malignancies and being extended towards solid cancers including PDAC. mesothelin (MSLN) and Carcinoembryonic Antigen (CEA) were reported to be highly overexpressed in KRAS-mutated PDAC. Meanwhile, in clinical trials, several CAR T-cell therapy studies are mainly focused towards these two cancer antigens in PDAC, however, the dual targeting of these two neoantigens is not reported. In the present study, we have designed and developed a novel dual-targeting CAR protein by employing various bioinformatics approaches such as functional analysis (antigenicity, allergenicity, antigen binding sites & signalling cascades), qualitative analysis (physicochemical, prediction, refinement & validation of 2D and 3D structures), molecular docking, and in silico cloning. Our results revealed that the designed CAR protein specifically binds with both MSLN & CEA with significant binding affinities, and was predicted to be stable & non-allergenic. Additionally, the protein-protein interaction network reveals the T-cell mediated antitumor responses of each domain in the designed CAR. Conclusively, we have designed and developed a dual targeting (MSLN & CEA) CAR protein towards KRAS-mutated PDAC using computational approaches. Alongside, we further recommend to engineer this designed CAR in T-cells and evaluating their therapeutic efficiency in in vitro and in vivo studies in the near future.

An Analysis of Genetic Polymorphisms in 76 Genes Related to the Development of Ovarian Tumors of Different Aggressiveness

Borderline ovarian tumors (BOTS) are rare neoplasms of intermediate aggressiveness between cystadenomas and low-grade ovarian cancers (lgOvCa), which they share some molecular resemblances with. In contrast to the most frequent and well-described high-grade ovarian carcinomas (hgOvCa), the molecular background of BOTS and lgOvCa is less thoroughly characterized. Here, we aimed to analyze genetic variants in crucial tumor suppressors and oncogenes in BOTS (with or without the BRAF V600E mutation), lgOvCa, and hgOvCa in two gene panels using next-generation sequencing. Then, we verified the existence of selected polymorphisms by Sanger sequencing. Finally, Western blot analyses were carried out to check the impact of the selected polymorphisms on the expression of the corresponding proteins. Our study contributes to the molecular characterization of ovarian neoplasms, demonstrating divergent polymorphic patterns pointing to distinct signaling pathways engaged in their development. Certain mutations seem to play an important role in BOTS without the BRAF V600E variant (KRAS) and in lgOvCa (KRAS and NRAS), but not in hgOvCa. Additionally, based on multivariable regression analyses, potential biomarkers in BOTS (PARP1) and hgOvCa (FANCI, BRCA2, TSC2, FANCF) were identified. Noteworthy, for some of the analyzed genes, such as FANCI, FANCD2, and FANCI, FANCF, TSC2, the status of BRCA1/2 and TP53, respectively, turned out to be crucial. Our results shed new light on the similarities and differences in the polymorphic patterns between ovarian tumors of diverse aggressiveness. Furthermore, the biomarkers identified herein are of potential use as predictors of the prognosis and/or response to therapy.

Identification of Ppy-lineage cells as a novel origin of pancreatic ductal adenocarcinoma

The Ppy gene encodes pancreatic polypeptide (PP) secreted by PP- or γ-cells, which are a subtype of endocrine cells localised mainly in the islet periphery. For a detailed characterisation of PP cells, we aimed to establish PP cell lines. To this end, we generated a mouse model harbouring the SV40 large T antigen (TAg) in the Rosa26 locus, which is expressed upon Ppy-promoter-mediated Cre-loxP recombination. Whereas Insulin1-CreERT-mediated TAg expression in beta cells resulted in insulinoma, surprisingly, Ppy-Cre-mediated TAg expression resulted in the malignant transformation of Ppy-lineage cells. These mice showed distorted islet structural integrity at 5 days of age compared with normal islets. CK19+ duct-like lesions contiguous with the islets were observed at 2 weeks of age, and mice developed aggressive pancreatic ductal adenocarcinoma (PDAC) at 4 weeks of age, suggesting that PDAC can originate from the islet/endocrine pancreas. This was unexpected as PDAC is believed to originate from the exocrine pancreas. RNA-sequencing analysis of Ppy-lineage islet cells from 7-day-old TAg+ mice showed a downregulation and an upregulation of endocrine and exocrine genes, respectively, in addition to the upregulation of genes and pathways associated with PDAC. These results suggest that the expression of an oncogene in Ppy-lineage cells induces a switch from endocrine cell fate to PDAC. Our findings demonstrate that Ppy-lineage cells may be an origin of PDAC and may provide novel insights into the pathogenesis of pancreatic cancer, as well as possible therapeutic strategies. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

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.

Reshaping the Tumor Microenvironment of KRASG12D Pancreatic Ductal Adenocarcinoma with Combined SOS1 and MEK Inhibition for Improved Immunotherapy Response

KRAS inhibitors have demonstrated exciting preclinical and clinical responses, although resistance occurs rapidly. Here, we investigate the effects of KRAS-targeting therapies on the tumor microenvironment using a library of KrasG12D, p53-mutant, murine pancreatic ductal adenocarcinoma-derived cell lines (KPCY) to leverage immune-oncology combination strategies for long-term tumor efficacy. Our findings show that SOS1 and MEK inhibitors (SOS1i+MEKi) suppressed tumor growth in syngeneic models and increased intratumoral CD8+ T cells without durable responses. Single-cell RNA sequencing revealed an increase in inflammatory cancer-associated fibroblasts (iCAF), M2 macrophages, and a decreased dendritic cell (DC) quality that ultimately resulted in a highly immunosuppressive microenvironment driven by IL6+ iCAFs. Agonist CD40 treatment was effective to revert macrophage polarization and overcome the lack of mature antigen-presenting DCs after SOS1i+MEKi therapy. Treatment increased the overall survival of KPCY tumor-bearing mice. The addition of checkpoint blockade to SOS1i+MEKi combination resulted in tumor-free mice with established immune memory. Our data suggest that KRAS inhibition affects myeloid cell maturation and highlights the need for combining KRAS cancer-targeted therapy with myeloid activation to enhance and prolong antitumor effects.

SIGNIFICANCE

Combination of SOS1 and MEK inhibitors increase T cell infiltration while blunting pro-immune myeloid cell maturation and highlights the need for combining KRAS cancer-targeted therapy with myeloid activation to enhance and prolong anti-tumor effects.

KRAS silencing alters chromatin physical organization and transcriptional activity in colorectal cancer cells

Clinical data revealed that KRAS mutant tumors, while initially sensitive to treatment, rapidly bypass KRAS dependence to acquire a drug-tolerant phenotype. However, the mechanisms underlying the transition from a drug-sensitive to a drug-tolerant state still elude us. Here, we show that global chromatin reorganization is a recurrent and specific feature of KRAS-dependent cells that tolerated KRAS silencing. We show that KRAS-dependent cells undergo G0/G1 cell cycle arrest after KRAS silencing, presenting a transcriptomic signature of quiescence. Proteomic analysis showed upregulated chromatin-associated proteins and transcription-associated biological processes. Accordingly, these cells shifted euchromatin/heterochromatin states, gained topologically associating domains, and altered the nanoscale physical organization of chromatin, more precisely by downregulating chromatin packing domains, a feature associated with the induction of quiescence. In addition, they also accumulated transcriptional alterations over time leading to a diversification of biological processes, linking chromatin alterations to transcriptional performance. Overall, our observations pinpoint a novel molecular mechanism of tolerance to KRAS oncogenic loss driven not by specific gene alterations but by global reorganization of genomic information, in which cells transition chromatin domain structure towards a more quiescent state and gain transcriptional reprogramming capacity.

Combination of mutations in genes controlling DNA repair and high mutational load plays a prognostic role in pancreatic ductal adenocarcinoma (PDAC): a retrospective real-life study in Sardinian population

BACKGROUND

Patients with pancreatic ductal adenocarcinoma (PDCA) carrying impaired mismatch repair mechanisms seem to have an outcome advantage under treatment with conventional chemotherapy, whereas the role for the tumor mutation burden on prognosis is controversial. In this study, we evaluated the prognostic role of the mutated genes involved in genome damage repair in a real-life series of PDAC patients in a hospital-based manner from the main Institution deputed to surgically treat such a disease in North Sardinia.

METHODS

A cohort of fifty-five consecutive PDAC patients with potentially resectable/border line resectable PDAC (stage IIB-III) or oligometastatic disease (stage IV) and tumor tissue availability underwent next-generation sequencing (NGS)-based analysis using a panel containing driver oncogenes and tumor suppressor genes as well as genes controlling DNA repair mechanisms.

RESULTS

Genes involved in the both genome damage repair (DR) and DNA mismatch repair (MMR) were found mutated in 17 (31%) and 15 (27%) cases, respectively. One fourth of PDAC cases (14/55; 25.5%) carried tumors presenting a combination of mutations in repair genes (DR and MMR) and the highest mutation load rates (MLR-H). After correction for confounders (surgery, adjuvant therapy, stage T, and metastasis), multivariate Cox regression analysis indicated that mutations in DR genes (HR = 3.0126, 95% CI 1.0707 to 8.4764, p = 0.0367) and the MLR (HR = 1.0018, 95%CI 1.0005 to 1.0032, p = 0.009) were significantly related to worse survival.

CONCLUSIONS

The combination of mutated repair genes and MLR-H, which is associated with a worse survival in our series of PDAC patients treated with conventional chemotherapy protocols, might become a predictive biomarker of response to immunotherapy in addition to its prognostic role in predicting survival.

Enhancing cholangiocarcinoma immunotherapy with adoptive T cells targeting HLA-restricted neoantigen peptides derived from driver gene mutations

Precision immunotherapy, driven by genomic and bioinformatic advancements, has emerged as a promising and viable approach to combat cancer. Targeting neoantigens offers the advantage of specific immune responses with minimal off-tumor toxicity. In this study, we investigated the potential of adoptive T cells activated by HLA-restricted neoantigen peptides from driver gene mutations for treating cholangiocarcinoma (CCA), a highly aggressive cancer with poor prognosis and high mortality rates. Through whole exome sequencing of CCA cell lines, KKU-213A and KKU-100, we identified mutations in common driver genes and predicted corresponding HLA-restricted peptides. Peptides from KRAS, RNF43, and TP53 mutations exhibited strong binding affinity to HLA-A11, as validated through molecular docking and T2-cell binding assays. Dendritic cells (DCs) from healthy donors expressing HLA-A* 11:01, pulsed with individual or pooled peptides, showed comparable levels of costimulatory molecules (CD11c, CD40, CD86, and HLA-DR) to conventional DCs but higher expression of maturation markers, CD80 and CD86. Autologous HLA-A* 11:01-restricted T cells, activated by peptide-pulsed DCs, effectively lysed KKU-213A (HLA-A*11:01) cells, outperforming conventional tumor lysate-pulsed DCs. This effect was specific to HLA-A* 11:01-restricted T cells and not observed in KKU-100 (HLA-A*33:03) cells. Moreover, HLA-A* 11:01-restricted T cells exhibited elevated levels of IFN-gamma, granulysin, and granzyme B, indicating their potent anti-tumor capabilities. These findings underscore the specificity and efficiency of HLA-A* 11:01-restricted T cells targeting KRAS, RNF43, TP53 mutated CCA cells, and offer valuable insights for developing immunotherapeutic strategies and therapeutic peptide-vaccines for CCA treatment.

Computational design and validation of effective siRNAs to silence oncogenic KRAS

Oncogenic KRAS mutations drive cancer progression in lung, colon, breast, and pancreatic ductal adenocarcinomas. Apart from the current strategies, such as KRAS upstream inhibitors, downstream effector inhibitors, interaction inhibitors, cell cycle inhibitors, and direct KRAS inhibitors, against KRAS-mutated cancers, the therapeutic small interfering RNAs (siRNAs) represent a promising alternative strategy that directly binds with the target mRNA and inhibits protein translation via mRNA degradation. Here, in the present study, we utilized various in silico approaches to design potential siRNA candidates against KRAS mRNA. We have predicted nearly 17 siRNAs against the KRAS mRNA, and further through various criteria, such as U, R, and A rules, GC%, secondary structure formation, mRNA-siRNA duplex stability, Tm (Cp), Tm (Conc), and inhibition efficiency, they have been filtered into 4 potential siRNAs namely siRNA8, siRNA11, siRNA12, and siRNA17. Further, the molecular docking analysis revealed that the siRNA8, siRNA11, siRNA12, and siRNA17 showed higher negative binding energies, such as - 379.13 kcal/mol, - 360.19 kcal/mol, - 288.47 kcal/mol, and - 329.76 kcal/mol, toward the human Argonaute2 protein (hAgo2) respectively. In addition, the normal mode analysis of the hAgo2-siRNAs complexes indicates the structural changes and deformation of the hAgo2 protein upon the binding of siRNA molecules in the dynamic environment which suggests that these siRNAs could be effective. Finally, we conclude that these 4 siRNAs have therapeutic potential against KRAS mRNA and also have to be studied in vitro and in vivo to evaluate their specificity toward mutant KRAS (not degrading wild-type KRAS). Also, the current challenges in the use of siRNA therapeutics could be overcome by the emerging siRNA delivery methods, such as Antibody-siRNA conjugates (ARCs) and Gelatin-Antibody Delivery System (GADS), in the near future and these siRNAs could be employed as potential therapeutic agents against KRAS-mutated cancers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03767-w.

Identification of novel peptide inhibitors for the KRas-G12C variant to prevent oncogenic signaling

Kirsten rat sarcoma viral oncogene homolog (KRas) activating mutations are common in solid tumors, accounting for 90%, 45%, and 35% of pancreatic, colorectal, and lung cancers (LC), respectively. Each year, nearly 150k new cases (both men and women) of KRas-mutated malignancies are reported in the United States. NSCLC (non-small cell lung cancer) accounts for 80% of all LC cases. KRas mutations are found in 15% to 25% of NSCLC patients. The main cause of NSCLC is the KRas-G12C mutation. The drugs Sotorasib and Adagrasib were recently developed to treat advanced NSCLC caused by the KRas-G12C mutation. Most patients do not respond to KRas-G12C inhibitors due to cellular, molecular, and genetic resistance. Because of their safety, efficacy, and selectivity, peptide inhibitors have the potential to treat newly developing KRas mutations. Based on the KRas mutations, peptide inhibitors that are highly selective and specific to individual lung cancers can be rationally designed. The current study uses an alanine and residue scanning approach to design peptide inhibitors for KRas-G12C based on the known peptide. Our findings show that substitution of F3K, G11T, L8C, T14C, K13D, G11S, and G11P considerably enhances the binding affinity of the novel peptides, whereas F3K, G11T, L8C, and T14C peptides have higher stability and favorable binding to the altered peptides. Overall, our study paves the road for the development of potential therapeutic peptidomimetics that target the KRas-G12C complex and may inhibit the KRas and SOS complex from interacting.Communicated by Ramaswamy H. Sarma.

Challenges in Diagnosing and Reporting Cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a challenge to the practicing surgical pathologist for several reasons. It is rare in many parts of the world, and thus practical exposure may be limited. Related to the fact of its rarity is the fact that more common tumors which frequently metastasize to the liver can be morphologically indistinguishable (eg, pancreatic ductal adenocarcinoma). Immunohistochemical testing is generally non-contributory in this context. Other difficulties arise from the protean morphologic manifestations of cholangiocarcinoma (ie, small duct vs. large duct) and the existence of combined cholangiocarcinoma and hepatocellular carcinoma. These, and other issues of concern to the practicing diagnostic pathologist are discussed herein.

Potential biomarkers uncovered by bioinformatics analysis in sotorasib resistant-pancreatic ductal adenocarcinoma

Background

Mutant KRAS-induced tumorigenesis is prevalent in lung, colon, and pancreatic ductal adenocarcinomas. For the past 3 decades, KRAS mutants seem undruggable due to their high-affinity GTP-binding pocket and smooth surface. Structure-based drug design helped in the design and development of first-in-class KRAS G12C inhibitor sotorasib (AMG 510) which was then approved by the FDA. Recent reports state that AMG 510 is becoming resistant in non-small-cell lung cancer (NSCLC), pancreatic ductal adenocarcinoma (PDAC), and lung adenocarcinoma patients, and the crucial drivers involved in this resistance mechanism are unknown.

Methods

In recent years, RNA-sequencing (RNA-seq) data analysis has become a functional tool for profiling gene expression. The present study was designed to find the crucial biomarkers involved in the sotorasib (AMG 510) resistance in KRAS G12C-mutant MIA-PaCa2 cell pancreatic ductal adenocarcinoma cells. Initially, the GSE dataset was retrieved from NCBI GEO, pre-processed, and then subjected to differentially expressed gene (DEG) analysis using the limma package. Then the identified DEGs were subjected to protein-protein interaction (PPI) using the STRING database, followed by cluster analysis and hub gene analysis, which resulted in the identification of probable markers.

Results

Furthermore, the enrichment and survival analysis revealed that the small unit ribosomal protein (RP) RPS3 is the crucial biomarker of the AMG 510 resistance in KRAS G12C-mutant MIA-PaCa2 cell pancreatic ductal adenocarcinoma cells.

Conclusion

Finally, we conclude that RPS3 is a crucial biomarker in sotorasib resistance which evades apoptosis by MDM2/4 interaction. We also suggest that the combinatorial treatment of sotorasib and RNA polymerase I machinery inhibitors could be a possible strategy to overcome resistance and should be studied in in vitro and in vivo settings in near future.

Oncogenic signaling pathways in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common (∼90% cases) pancreatic neoplasm and one of the most lethal cancer among all malignances. PDAC harbor aberrant oncogenic signaling that may result from the multiple genetic and epigenetic alterations such as the mutation in driver genes (KRAS, CDKN2A, p53), genomic amplification of regulatory genes (MYC, IGF2BP2, ROIK3), deregulation of chromatin-modifying proteins (HDAC, WDR5) among others. A key event is the formation of Pancreatic Intraepithelial Neoplasia (PanIN) that often results from the activating mutation in KRAS. Mutated KRAS can direct a variety of signaling pathways and modulate downstream targets including MYC, which play an important role in cancer progression. In this review, we discuss recent literature shedding light on the origins of PDAC from the perspective of major oncogenic signaling pathways. We highlight how MYC directly and indirectly, with cooperation with KRAS, affect epigenetic reprogramming and metastasis. Additionally, we summarize the recent findings from single cell genomic approaches that highlight heterogeneity in PDAC and tumor microenvironment, and provide molecular avenues for PDAC treatment in the future.

Triple negative breast tumors contain heterogeneous cancer cells expressing distinct KRAS-dependent collective and disseminative invasion programs

Inter-patient and intra-tumoral heterogeneity complicate the identification of predictive biomarkers and effective treatments for basal triple negative breast cancer (b-TNBC). Invasion is the initiating event in metastasis and can occur by both collective and single-cell mechanisms. We cultured primary organoids from a b-TNBC genetically engineered mouse model in 3D collagen gels to characterize their invasive behavior. We observed that organoids from the same tumor presented different phenotypes that we classified as non-invasive, collective and disseminative. To identify molecular regulators driving these invasive phenotypes, we developed a workflow to isolate individual organoids from the collagen gels based on invasive morphology and perform RNA sequencing. We next tested the requirement of differentially regulated genes for invasion using shRNA knock-down. Strikingly, KRAS was required for both collective and disseminative phenotypes. We then performed a drug screen targeting signaling nodes upstream and downstream of KRAS. We found that inhibition of EGFR, MAPK/ERK, or PI3K/AKT signaling reduced invasion. Of these, ERK inhibition was striking for its ability to potently inhibit collective invasion and dissemination. We conclude that different cancer cells in the same b-TNBC tumor can express different metastatic molecular programs and identified KRAS and ERK as essential regulators of collective and single cell dissemination.

Unraveling the Complex Interconnection between Specific Inflammatory Signaling Pathways and Mechanisms Involved in HIV-Associated Colorectal Oncogenesis

The advancement of HIV treatment has led to increased life expectancy. However, people living with HIV (PLWH) are at a higher risk of developing colorectal cancers. Chronic inflammation has a key role in oncogenesis, affecting the initiation, promotion, transformation, and advancement of the disease. PLWH are prone to opportunistic infections that trigger inflammation. It has been documented that 15-20% of cancers are triggered by infections, and this percentage is expected to be increased in HIV co-infections. The incidence of parasitic infections such as helminths, with Ascariasis being the most common, is higher in HIV-infected individuals. Cancer cells and opportunistic infections drive a cascade of inflammatory responses which assist in evading immune surveillance, making them survive longer in the affected individuals. Their survival leads to a chronic inflammatory state which further increases the probability of oncogenesis. This review discusses the key inflammatory signaling pathways involved in disease pathogenesis in HIV-positive patients with colorectal cancers. The possibility of the involvement of co-infections in the advancement of the disease, along with highlights on signaling mechanisms that can potentially be utilized as therapeutic strategies to prevent oncogenesis or halt cancer progression, are addressed.

Multiscale Analysis and Validation of Effective Drug Combinations Targeting Driver KRAS Mutations in Non-Small Cell Lung Cancer

Pharmacogenomics is a rapidly growing field with the goal of providing personalized care to every patient. Previously, we developed the Computational Analysis of Novel Drug Opportunities (CANDO) platform for multiscale therapeutic discovery to screen optimal compounds for any indication/disease by performing analytics on their interactions using large protein libraries. We implemented a comprehensive precision medicine drug discovery pipeline within the CANDO platform to determine which drugs are most likely to be effective against mutant phenotypes of non-small cell lung cancer (NSCLC) based on the supposition that drugs with similar interaction profiles (or signatures) will have similar behavior and therefore show synergistic effects. CANDO predicted that osimertinib, an EGFR inhibitor, is most likely to synergize with four KRAS inhibitors.Validation studies with cellular toxicity assays confirmed that osimertinib in combination with ARS-1620, a KRAS G12C inhibitor, and BAY-293, a pan-KRAS inhibitor, showed a synergistic effect on decreasing cellular proliferation by acting on mutant KRAS. Gene expression studies revealed that MAPK expression is strongly correlated with decreased cellular proliferation following treatment with KRAS inhibitor BAY-293, but not treatment with ARS-1620 or osimertinib. These results indicate that our precision medicine pipeline may be used to identify compounds capable of synergizing with inhibitors of KRAS G12C, and to assess their likelihood of becoming drugs by understanding their behavior at the proteomic/interactomic scales.

A New View of Activating Mutations in Cancer

A vast effort has been invested in the identification of driver mutations of cancer. However, recent studies and observations call into question whether the activating mutations or the signal strength are the major determinant of tumor development. The data argue that signal strength determines cell fate, not the mutation that initiated it. In addition to activating mutations, factors that can impact signaling strength include (i) homeostatic mechanisms that can block or enhance the signal, (ii) the types and locations of additional mutations, and (iii) the expression levels of specific isoforms of genes and regulators of proteins in the pathway. Because signal levels are largely decided by chromatin structure, they vary across cell types, states, and time windows. A strong activating mutation can be restricted by low expression, whereas a weaker mutation can be strengthened by high expression. Strong signals can be associated with cell proliferation, but too strong a signal may result in oncogene-induced senescence. Beyond cancer, moderate signal strength in embryonic neural cells may be associated with neurodevelopmental disorders, and moderate signals in aging may be associated with neurodegenerative diseases, like Alzheimer's disease. The challenge for improving patient outcomes therefore lies in determining signaling thresholds and predicting signal strength.

FAK promotes stromal PD-L2 expression associated with poor survival in pancreatic cancer

BACKGROUND

Pancreatic Cancer is one of the most lethal cancers, with less than 8% of patients surviving 5 years following diagnosis. The last 40 years have seen only small incremental improvements in treatment options, highlighting the continued need to better define the cellular and molecular pathways contributing to therapy response and patient prognosis.

METHODS

We combined CRISPR, shRNA and flow cytometry with mechanistic experiments using a KrasG12Dp53R172H mouse model of pancreatic cancer and analysis of publicly available human PDAC transcriptomic datasets.

RESULTS

Here, we identify that expression of the immune checkpoint, Programmed Death Ligand 2 (PD-L2), is associated with poor prognosis, tumour grade, clinical stage and molecular subtype in patients with Pancreatic Ductal Adenocarcinoma (PDAC). We further show that PD-L2 is predominantly expressed in the stroma and, using an orthotopic murine model of PDAC, identify cancer cell-intrinsic Focal Adhesion Kinase (FAK) signalling as a regulator of PD-L2 stromal expression. Mechanistically, we find that FAK regulates interleukin-6, which can act in concert with interleukin-4 secreted by CD4 T-cells to drive elevated expression of PD-L2 on tumour-associated macrophages, dendritic cells and endothelial cells.

CONCLUSIONS

These findings identify further complex heterocellular signalling networks contributing to FAK-mediated immune suppression in pancreatic cancer.

Identification of novel natural drug candidates against BRAF mutated carcinoma; An integrative in-silico structure-based pharmacophore modeling and virtual screening process

The BRAF gene is responsible for transferring signals from outside of the cell to inside of the nucleus by converting a protein namely B-Raf through the RAS/MAPK pathway. This pathway contribute to cell division, proliferation, migration, and apoptotic cell death of human and animal. Mutation in this gene may cause the development of several cancers, including lung, skin, colon, and neuroblastoma. Currently, a few available drugs are being used that has developed by targeting the BRAF mutated protein, and due to the toxic side effects, patients suffer a lot during their treatment. Therefore this study aimed to identify potentially lead compounds that can target and block the expression of BRAF and subsequently inhibit the cancer. The hits were generated through the pharmacophore model-based virtual screening, molecular docking, pharmacohore model validation, ADME (absorption, distribution, metabolism, and excretion) analysis molecular dynamics (MD) simulation to find more suitable candidate against the overexpress BRAF gene. The pharmacophore based screening initially identified 14 k possible hits from online database which were further screened by ligand scout advance software to get hit compound. Based on molecular docking score of ZINC70454679 (-10.6 kcal/mol), ZINC253500968 (-9.4 kcal/mol), ZINC106887736 (-8.6 kcal/mol), and ZINC107434492 (-8.1 kcal/mol), pharmacophore feature and toxicity evaluation, we selected four possible lead compounds. The dynamic simulation with Schrodinger Maestro software was used to determine the stability of the potential lead candidates with target protein (PDB ID: 5VAM). The results showed that the newly obtained four compounds were more stable than the control ligand (Pub Chem ID: 90408826). The current results showed that the ZINC70454679, ZINC253500968, ZINC106887736, and ZINC107434492 compounds may be able to work against several cancers through targeting the BRAF overexpressed gene. To develop a novel drug candidate, however the evaluation of the web lab based experimental work are necessary to evaluate the efficiency of the each compound against the BRAF target gene.

KRAS mutated Non-Small Lung Carcinoma: A Real World Context from the Indian subcontinent

BACKGROUND

KRAS, although a common variant of occurrence (~20% of non-small-cell lung carcinoma [NSCLC]) has been untargetable, owing to the molecular structure which inherently prevents drug binding. KRAS mutations in NSCLC are associated with distinct clinical profiles including smokers and mucinous histology. KRAS G12C mutations account for ~40% KRAS altered NSCLC, but NSCLC being a geographically diverse disease, the features may be distinct in this part of the world. This is a single-center experience of KRAS-mutated NSCLC including clinical, imaging, pathologic features, and treatment patterns and outcomes.

METHODS

This is a single-center retrospective study of KRAS-mutated NSCLC. The clinicopathological features and outcomes were retrieved and collated from the medical record archives of the hospital.

RESULTS

Fifty (30.6%) patients with advanced-stage NSCLC with alterations in the KRAS gene were enrolled in the 163 patients who were tested for KRAS alterations. The median age was 61 years. Molecular detection revealed three main types of KRAS mutations viz-a-vis: G12C in 17 (34%), G12V in 9 (18%), and G12D in 6 (12%) patients. Comparing G12C versus the non-G12C mutated cases, co-mutations were common in the non-G12C subgroup (p < 0.05). Among the 36, who were treated at our center, all received chemotherapy as the first line with a median progression-free survival (PFS)of 5.4 months. The PFS of G12C was higher than the non-G12C subgroup (6.4 vs 3.8 months).

CONCLUSION

This is the largest single-center experience from the Indian subcontinent for KRAS-mutated NSCLC with distinct clinical features. It highlights the unmet need for G12C inhibitors in our country, where prevalence is equivalent to the West.

Cytotoxicity of combinations of the pan-KRAS SOS1 inhibitor BAY-293 against pancreatic cancer cell lines

KRAS is mutated in approximately 25% of cancer patients and first KRAS G12C-specific inhibitors showed promising responses. Pancreatic cancer has the highest frequency of KRAS mutations but the prevailing KRAS G12D mutation is difficult to target. Inhibition of the GTP exchange factor (GEF) SOS1-KRAS interaction impairs oncogenic signaling independently of the specific KRAS mutations. In general, cell lines exhibiting KRAS mutations show specific alterations in respect to glucose utilization, signal transduction and stress survival. The aim of this investigation was to check the putative synergy of the SOS1 inhibitor BAY-293 with modulators targeting specific vulnerabilities of KRAS-mutated cell lines in vitro. The cytotoxicity of BAY-293 combinations was tested against MIA PaCa-2 (G12C), AsPC1 (G12D) and BxPC3 (KRAS wildtype) cell lines using MTT tests and calculation of the combination indices (CI) according to the Chou-Talalay method. The results show that BAY-293 synergizes with modulators of glucose utilization, inhibitors of the downstream MAPK pathway and several chemotherapeutics in dependence of the specific KRAS status of the cell lines. In particular, divergent responses for BAY-293 combinations between pancreatic and NSCLC cell lines were observed for linsitinib, superior inhibitory effects of trametinib and PD98059 in NSCLC, and lack of activity with doxorubicin in case of the pancreatic cell lines. Phosphoproteome analysis revealed inhibition of distinct signaling pathways by BAY-293 for MIA PaCa-2 on the one hand and for Aspc1 and BH1362 on the other hand. In conclusion, BAY-293 exhibits synergy with drugs in dependence of the tumor type and specific KRAS mutation.

Sensitivity towards HDAC inhibition is associated with RTK/MAPK pathway activation in gastric cancer

Gastric cancer ranks the fifth most common and third leading cause of cancer-related deaths worldwide. Alterations in the RTK/MAPK, WNT, cell adhesion, TP53, TGFβ, NOTCH, and NFκB signaling pathways could be identified as main oncogenic drivers. A combination of altered pathways can be associated with molecular subtypes of gastric cancer. In order to generate model systems to study the impact of different pathway alterations in a defined genetic background, we generated three murine organoid models: a RAS-activated (Kras^G12D , Tp53^R172H ), a WNT-activated (Apc^fl/fl , Tp53^R172H ), and a diffuse (Cdh1^fl/fl , Apc^fl/fl ) model. These organoid models were morphologically and phenotypically diverse, differed in proteome expression signatures and possessed individual drug sensitivities. A differential vulnerability to RTK/MAPK pathway interference based on the different mitogenic drivers and according to the level of dependence on the pathway could be uncovered. Furthermore, an association between RTK/MAPK pathway activity and susceptibility to HDAC inhibition was observed. This finding was further validated in patient-derived organoids from gastric adenocarcinoma, thus identifying a novel treatment approach for RTK/MAPK pathway altered gastric cancer patients.

Low Impact of Clonal Hematopoiesis on the Determination of RAS Mutations by Cell-Free DNA Testing in Routine Clinical Diagnostics

Targeted sequencing of circulating cell-free DNA (cfDNA) is used in routine clinical diagnostics for the identification of predictive biomarkers in cancer patients in an advanced stage. The presence of KRAS mutations associated with clonal hematopoiesis of indeterminate potential (CHIP) might represent a confounding factor. We used an amplicon-based targeted sequencing panel, covering selected regions of 52 genes, for circulating cell-free total nucleic acid (cfTNA) analysis of 495 plasma samples from cancer patients. The cfDNA test failed in 4 cases, while circulating cell-free RNA (cfRNA) sequencing was invalid in 48 cases. In the 491 samples successfully tested on cfDNA, at least one genomic alteration was found in 222 cases (45.21%). We identified 316 single nucleotide variants (SNVs) in 21 genes. The most frequently mutated gene was TP53 (74 variants), followed by KRAS (71), EGFR (56), PIK3CA (33) and BRAF (19). Copy number variations (CNVs) were detected in 36 cases, while sequencing of cfRNA revealed 6 alterations. Analysis with droplet digital PCR (ddPCR) of peripheral blood leukocyte (PBL)-derived genomic DNA did not identify any KRAS mutations in 39 cases that showed KRAS mutations at cfDNA analysis. These findings suggest that the incidence of CHIP-associated KRAS mutations is relatively rare in routine clinical diagnostics.

Conformational Dynamics Allows Sampling of an "Active-like" State by Oncogenic K-Ras-GDP

Mutations in K-Ras GTPase replacing Gly12 with either Asp or Val are common in cancer. These mutations decelerate intrinsic and catalyzed GTP hydrolysis, leading to accumulation of K-Ras-GTP in cells. Signaling cascades initiated by K-Ras-GTP promote cell proliferation, survival, and invasion. Despite functional differences between the most frequent G12D mutation and the most aggressive and chemotherapy resistant G12V mutation, their long-suspected distinct structural features remain elusive. Using NMR, X-ray structures, and computational methods, we found that oncogenic mutants of K-Ras4B, the predominant splice variant of K-Ras, exhibit distinct conformational dynamics when GDP-bound, visiting the "active-like" conformational state similar to the one observed in GTP-bound K-Ras. This behavior distinguishes G12V from wild type and G12D K-Ras4B-GDP. The likely reason is hydrophobic interactions between the aliphatic sidechain of V12 and the Switch II region of K-Ras4B^G12V-GDP, which are distinct in K-Ras4B^G12D-GDP. In the X-ray structures, crystal contacts reduce the dynamics of the sidechain at position 12 by stabilizing the Switch I region of the protein. This explains why structural differences between G12V and G12D K-Ras have yet not been reported. Together, our results suggest a previously unknown mechanism of K-Ras activation. This mechanism relies on conformational dynamics caused by specific oncogenic mutations in the GDP-bound state. Our findings also imply that the therapeutic strategies decreasing the level of K-Ras-GTP by interfering with nucleotide exchange or by expediting GTP hydrolysis may work differently in different oncogenic mutants.

Multidrug Resistance in Cancer Cells: Focus on a Possible Strategy Plan to Address Colon Carcinoma Cells

Even though various treatment methods are available for cancer, the death curve is not reducing. The diagnosis of cancer at the fourth stage and drug resistance are the leading reasons for treatment failure and lower survival rates. In this review article, we summarize the possible pitfalls during cancer treatment in general, which mainly include multidrug resistance, and propose a hypothesis for colorectal cancer specifically. We also evaluate multidrug resistance in cancer in general and colorectal cancer in particular and hypothesize a concept based on combination therapy with 5-fluorouracil, curcumin, and lipids for the possible management of colorectal cancer. In addition, a hypothetical approach, combining a synthetic agent and a natural chemotherapeutic agent, to treating colorectal cancer is also discussed. This hypothesis could improve the management of colorectal cancer.

Prognostic Value of Drug Targets Predicted Using Deep Bioinformatic Analysis of m6A-Associated lncRNA-Based Pancreatic Cancer Model Characteristics and Its Tumour Microenvironment

The role of N6-methyladenosine (m6A)-associated long-stranded non-coding RNA (lncRNA) in pancreatic cancer is unclear. Therefore, we analysed the characteristics and tumour microenvironment in pancreatic cancer and determined the value of m6A-related lncRNAs for prognosis and drug target prediction. An m6A-lncRNA co-expression network was constructed using The Cancer Genome Atlas database to screen m6A-related lncRNAs. Prognosis-related lncRNAs were screened using univariate Cox regression; patients were divided into high- and low-risk groups and randomised into training and test groups. In the training group, least absolute shrinkage and selection operator (LASSO) was used for regression analysis and to construct a prognostic model, which was validated in the test group. Tumor mutational burden (TMB), immune evasion, and immune function of risk genes were analysed using R; drug sensitivity and potential drugs were examined using the Genomics of Drug Sensitivity in Cancer database. We screened 129 m6A-related lncRNAs; 17 prognosis-related m6A-related lncRNAs were obtained using multivariate analysis and three m6A-related lncRNAs (AC092171.5, MEG9, and AC002091.1) were screened using LASSO regression. Survival rates were significantly higher (p < 0.05) in the low-risk than in the high-risk group. Risk score was an independent predictor affecting survival (p < 0.001), with the highest risk score being obtained by calculating the c-index. The TMB significantly differed between the high- and low-risk groups (p < 0.05). In the high- and low-risk groups, mutations were detected in 61 of 70 samples and 49 of 71 samples, respectively, with KRAS, TP53, and SMAD4 showing the highest mutation frequencies in both groups. A lower survival rate was observed in patients with a high versus low TMB. Immune function HLA, Cytolytic activity, and Inflammation-promoting, T cell co-inhibition, Check-point, and T cell co-stimulation significantly differed in different subgroups (p < 0.05). Immune evasion scores were significantly higher in the high-risk group than in the low-risk group. Eight sensitive drugs were screened: ABT.888, ATRA, AP.24534, AG.014699, ABT.263, axitinib, A.443654, and A.770041. We screened m6A-related lncRNAs using bioinformatics, constructed a prognosis-related model, explored TMB and immune function differences in pancreatic cancer, and identified potential therapeutic agents, providing a foundation for further studies of pancreatic cancer diagnosis and treatment.

Strategies of targeting KRAS, challenging drug target

In the developed world, cancer is the most common cause of death. Among the 36 human genes of the RAS family, KRAS, NRAS, and HRAS play a prominent role in human cancer. KRAS belongs to the Rassuperfamily of proteins and is a small GTPase signal transduction protein. Among the RAS isoform, KRAS is the dominant mutant that induced approximately 86% of the RAS mutations. The most frequently mutated KRAS isoform is KRAS4B, about 90% of pancreatic cancer, 30-40% of colon cancer, and 15 to 20% of lung cancers are caused by mutations KRAS4B isoform. Liver cancer, bladder cancer, breast cancer, and myeloid leukaemia are also caused by mutations in KRAS but are rare. Currently, no FDA-approved drugs are available for KRAS-driven cancer. As the RAS proteins lack a right pocket accessible to the chemical inhibitors, the cancer-causing mutant proteins are almost identical to their essential wild-type counterparts. Therefore, it was considered undruggable. The structure and function of new insights in RAS have changed this understanding and encouraged the development of many drug candidates. This review provides information about the different strategies of targeting KRAS, a challenging drug target that might be valuable for the scientific community.

Expanding the Reach of Precision Oncology by Drugging All KRAS Mutants

KRAS is the most frequently mutated oncogene, harboring mutations in approximately one in seven cancers. Allele-specific KRASG12C inhibitors are currently changing the treatment paradigm for patients with KRASG12C-mutated non-small cell lung cancer and colorectal cancer. The success of addressing a previously elusive KRAS allele has fueled drug discovery efforts for all KRAS mutants. Pan-KRAS drugs have the potential to address broad patient populations, including KRASG12D-, KRASG12V-, KRASG13D-, KRASG12R-, and KRASG12A-mutant or KRAS wild-type-amplified cancers, as well as cancers with acquired resistance to KRASG12C inhibitors. Here, we review actively pursued allele-specific and pan-KRAS inhibition strategies and their potential utility.

SIGNIFICANCE

Mutant-selective KRASG12C inhibitors target a fraction (approximately 13.6%) of all KRAS-driven cancers. A broad arsenal of KRAS drugs is needed to comprehensively conquer KRAS-driven cancers. Conceptually, we foresee two future classes of KRAS medicines: mutant-selective KRAS drugs targeting individual variant alleles and pan-KRAS therapeutics targeting a broad range of KRAS alterations.

Lung Adenocarcinoma Tumor Origin: A Guide for Personalized Medicine

Simple Summary

Lung cancer is the leading cause of cancer-related death worldwide, with an average 5-year survival rate of approximately 15%. Among the multiple histological type of lung cancer, adenocarcinoma is the most common. Adenocarcinoma is characterized by a high degree of heterogeneity at many levels, including histological, cellular, and molecular. Understanding the cell of origin of adenocarcinoma, and the molecular changes during tumor progression, will allow better therapeutic strategies.

Abstract

Lung adenocarcinoma, the major form of lung cancer, is the deadliest cancer worldwide, due to its late diagnosis and its high heterogeneity. Indeed, lung adenocarcinoma exhibits pronounced inter- and intra-tumor heterogeneity cofounding precision medicine. Tumor heterogeneity is a clinical challenge driving tumor progression and drug resistance. Several key pieces of evidence demonstrated that lung adenocarcinoma results from the transformation of progenitor cells that accumulate genetic abnormalities. Thus, a better understanding of the cell of origin of lung adenocarcinoma represents an opportunity to unveil new therapeutic alternatives and stratify patient tumors. While the lung is remarkably quiescent during homeostasis, it presents an extensive ability to respond to injury and regenerate lost or damaged cells. As the lung is constantly exposed to potential insult, its regenerative potential is assured by several stem and progenitor cells. These can be induced to proliferate in response to injury as well as differentiate into multiple cell types. A better understanding of how genetic alterations and perturbed microenvironments impact progenitor-mediated tumorigenesis and treatment response is of the utmost importance to develop new therapeutic opportunities.

Acoustic Array Biochip Combined with Allele-Specific PCR for Multiple Cancer Mutation Analysis in Tissue and Liquid Biopsy

Regular screening of point mutations is of importance to cancer management and treatment selection. Although techniques like next-generation sequencing and digital polymerase chain reaction (PCR) are available, these are lacking in speed, simplicity, and cost-effectiveness. The development of alternative methods that can detect the extremely low concentrations of the target mutation in a fast and cost-effective way presents an analytical and technological challenge. Here, an approach is presented where for the first time an allele-specific PCR (AS-PCR) is combined with a newly developed high fundamental frequency quartz crystal microbalance array as biosensor for the amplification and detection, respectively, of cancer point mutations. Increased sensitivity, compared to fluorescence detection of the AS-PCR amplicons, is achieved through energy dissipation measurement of acoustically "lossy" liposomes binding to surface-anchored dsDNA targets. The method, applied to the screening of BRAF V600E and KRAS G12D mutations in spiked-in samples, was shown to be able to detect 1 mutant copy of genomic DNA in an excess of 10⁴ wild-type molecules, that is, with a mutant allele frequency (MAF) of 0.01%. Moreover, validation of tissue and plasma samples obtained from melanoma, colorectal, and lung cancer patients showed excellent agreement with Sanger sequencing and ddPCR; remarkably, the efficiency of this AS-PCR/acoustic methodology to detect mutations in real samples was demonstrated to be below 1% MAF. The combined high sensitivity and technology-readiness level of the methodology, together with the ability for multiple sample analysis (24 array biochip), cost-effectiveness, and compatibility with routine workflow, make this approach a promising tool for implementation in clinical oncology labs for tissue and liquid biopsy.

Novel systemic treatment approaches for metastatic pancreatic cancer

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) has a 5-year overall survival rate of 10 %, emphasizing the need for more effective therapies, especially in metastatic disease. The immunosuppressive tumor microenvironment, poor vascularization, and dense tumor stroma typical for PDAC are hurdles that need to be overcome by novel drugs. Investigations are moving towards more targeted treatments including immunotherapy and cell-based approaches.

AREAS COVERED

This article reviews emerging drugs in clinical development for metastatic PDAC, focusing on cellular therapies and novel treatments targeting metabolism, tumor stroma, oncogenic pathways and immunosuppression. With immunotherapy and CAR T cell therapy on the rise in hematological malignancies, the transfer to solid tumors remains intriguing. Multiple exciting clinical trials investigating innovative therapeutic strategies for PDAC are currently ongoing and reviewed herein. ClinicalTrials.gov, conference abstracts and PubMed were searched in August 2021 and assessed for information on ongoing and published clinical studies.

EXPERT OPINION

With many challenges to overcome, the optimal therapy for patients with metastatic PDAC is likely to consist of a combination of different agents. We are slowly moving from entity-dependent approaches to ones more focused on molecular and pathological features. Increasingly personalized treatment plans tailored to each patient may be the future of PDAC therapy.

Resistance to KRASG12C Inhibitors in Non-Small Cell Lung Cancer

KRAS mutations are one of the most prevalent oncogenic alterations in cancer. Until recently, drug development targeting KRAS did not convey clinical benefits to patients. Specific KRASG12C inhibitors, such as sotorasib and adagrasib, have been designed to bind to the protein's mutant structure and block KRASG12C in its GDP-bound inactive state. Phase 1/2 trials have shown promising anti-tumor activity, especially in pretreated non-small cell lung cancer patients. As expected, both primary and secondary resistance to KRASG12C inhibitors invariably occurs, and molecular mechanisms have been characterized in pre-clinical models and patients. Several mechanisms such as tyrosine kinase receptors (RTKs) mediated feedback reactivation of ERK-dependent signaling can result in intrinsic resistance to KRAS target therapy. Acquired resistance to KRASG12C inhibitors include novel KRAS mutations such as Y96D/C and other RAS-MAPK effector protein mutations. This review focuses on the intrinsic and acquired mechanisms of resistance to KRASG12C inhibitors in KRASG12C mutant non-small cell lung cancer and the potential clinical strategies to overcome or prevent it.

Targeting KRAS mutant lung cancer: light at the end of the tunnel

For decades, KRAS mutant lung adenocarcinomas (LUAD) have been refractory to therapeutic strategies based on personalized medicine owing to the complexity of designing inhibitors to selectively target KRAS and downstream targets with acceptable toxicities. The recent development of selective KRAS^G12C inhibitors represents a landmark after 40 years of intense research efforts since the identification of KRAS as a human oncogene. Here, we discuss the mechanisms responsible for the rapid development of resistance to these inhibitors, as well as potential strategies to overcome this limitation. Other therapeutic strategies aimed at inhibiting KRAS oncogenic signaling by targeting either upstream activators or downstream effectors are also reviewed. Finally, we discuss the effect of targeting the mitogen‐activated protein kinase (MAPK) pathway, both based on the failure of MEK and ERK inhibitors in clinical trials, as well as on the recent identification of RAF1 as a potential target due to its MAPK‐independent activity. These new developments, taken together, are likely to open new avenues to effectively treat KRAS mutant LUAD.

Resectable and Borderline Resectable Pancreatic Ductal Adenocarcinoma: Role of the Radiologist and Oncologist in the Era of Precision Medicine

The incidence and mortality of pancreatic ductal adenocarcinoma are growing over time. The management of patients with pancreatic ductal adenocarcinoma involves a multidisciplinary team, ideally involving experts from surgery, diagnostic imaging, interventional endoscopy, medical oncology, radiation oncology, pathology, geriatric medicine, and palliative care. An adequate staging of pancreatic ductal adenocarcinoma and re-assessment of the tumor after neoadjuvant therapy allows the multidisciplinary team to choose the most appropriate treatment for the patient. This review article discusses advancement in the molecular basis of pancreatic ductal adenocarcinoma, diagnostic tools available for staging and tumor response assessment, and management of resectable or borderline resectable pancreatic cancer.

Analysis of KRAS Mutation Subtype in Tissue DNA and Cell-Free DNA Using Droplet Digital PCR and the Function of Cell-Free DNA as a Recurrence Predictive Marker in Pancreatic Cancer

KRAS mutation is a major regulator in the tumor progression of pancreatic cancer. Here, we compared the frequency and mutation burden of KRAS mutation subtypes with paired tumor tissue and blood in patients and examined their clinical significance. DNA from tumor tissues and cell-free DNA (cfDNA) from preoperative blood were obtained from 70 patients with pancreatic cancer. Subtypes and mutation burdens of KRAS G12D and G12V mutations were evaluated using droplet digital PCR. Comparing the presence of mutations in tissue, accumulative and simultaneous mutations of G12D or G12V were identified of 67 (95.7%), and 48 patients (68.6%). Conversely, in blood, they were only identified in 18 (25.7%) and four (5.7%) patients; respectively. Next, comparing the mutation burden in tissue, the mutation burden varied from less than 0.1 to more than five, whereas that of cfDNA in blood was mostly between one and five, as cases with a mutation burden lower than 0.1 and higher than five were rare. Finally, the presence of the G12V mutation alone in cfDNA and the combination of the G12V mutation with elevated CA 19-9 levels were associated with poor recurrence-free survival. These fundamental data on the KRAS mutation subtypes and their clinical significance could support their potential as predictive markers for postoperative recurrence.

m6A Methylation Modification Patterns and Tumor Microenvironment Infiltration Characterization in Pancreatic Cancer

Recent studies have shown that RNA N⁶-methyladenosine (m⁶A) modification plays an important part in tumorigenesis and immune-related biological processes. However, the comprehensive landscape of immune cell infiltration characteristics in the tumor microenvironment (TME) mediated by m⁶A methylation modification in pancreatic cancer has not yet been elucidated. Based on consensus clustering algorithm, we identified two m⁶A modification subtypes and then determined two m⁶A-related gene subtypes among 434 pancreatic cancer samples. The TME characteristics of the identified gene subtypes were highly consistent with the immune-hot phenotype and the immune-cold phenotype respectively. According to the m⁶A score extracted from the m⁶A-related signature genes, patients can be divided into high and low m⁶A score groups. The low score group displayed a better prognosis and relatively strong immune infiltration. Further analysis showed that low m⁶A score correlated with lower tumor mutation burden and PD-L1 expression, and indicated a better response to immunotherapy. In general, m⁶A methylation modification is closely related to the diversity and complexity of immune infiltration in TME. Evaluating the m⁶A modification pattern and immune infiltration characteristics of individual tumors can help deepen our understanding of the tumor microenvironment landscape and promote a more effective clinical practice of immunotherapy.