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The clear importance of mutated KRAS as a therapeutic target has driven the investigation of multiple approaches to inhibit oncogenic KRAS signaling at different molecular levels. ...However, no KRAS-targeted therapy has reached the clinic to date, which underlies the intrinsic difficulty in developing effective, direct inhibitors of KRAS. Thus, this article provides an overview of the history and recent progress in the development of pharmacological strategies to target oncogenic KRAS with small molecule agents. Mechanistically, these KRAS-targeted agents can be classified into the following four categories. (1) Small-molecule RAS-binding ligands that prevent RAS activation by binding within or outside the nucleotide-binding motif. (2) Inhibitors of KRAS membrane anchorage. (3) Inhibitors that bind to RAS-binding domains of RAS-effector proteins. (4) Inhibitors of KRAS expression. The advantage and limitation of each type of these anti-KRAS agents are discussed.
Kirsten Rat Sarcoma (KRAS) is a master oncogene involved in cellular proliferation and survival and is the most commonly mutated oncogene in all cancers. Activating KRAS mutations are present in over ...90% of pancreatic ductal adenocarcinoma (PDAC) cases and are implicated in tumor initiation and progression. Although KRAS is a critical oncogene, and therefore an important therapeutic target, its therapeutic inhibition has been very challenging, and only recently specific mutant KRAS inhibitors have been discovered. In this review, we discuss the activation of KRAS signaling and the role of mutant KRAS in PDAC development. KRAS has long been considered undruggable, and many drug discovery efforts which focused on indirect targeting have been unsuccessful. We discuss the various efforts for therapeutic targeting of KRAS. Further, we explore the reasons behind these obstacles, novel successful approaches to target mutant KRAS including G12C mutation as well as the mechanisms of resistance.
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•GTF3C6 is upregulated in LUAD tissues, LSL-KrasG12D/+;LSL-p53−/− LUAD mouse models and LUAD organoid.•Upregulation of GTF3C6 is associated with an unfavorable clinical prognosis in ...LUAD.•GTF3C6 is driven by KRAS/PI3K axis in LUAD.•GTF3C6 promotes anchorage-independent proliferation, migration, and invasion of LUAD cells via FAK pathway.
Effective targeting drugs for KRAS mutation-mediated Lung Adenocarcinoma (LUAD) are currently are limited.
Investigating and intervening in the downstream key target genes of KRAS is crucial for clinically managing KRAS mutant-driven LUAD. GTF3C6, a newly identified member of the general transcription factor III (GTF3) family, plays a role in the transcription of RNA polymerase III (pol III)-dependent genes. However, its involvement in cancer remains unexplored.
This study examined the expression, roles, and potential molecular mechanisms of GTF3C6 in LUAD tissues, LSL-KrasG12D/+;LSL-p53−/− LUAD mouse models, and LUAD patients-derived organoid using Western blot, qRT-PCR, immunofluorescence, immunohistochemistry, and gene manipulation assays.
We present the first evidence that GTF3C6 is highly expressed in LUAD tissues, LSL-KrasG12D/+;LSL-p53−/− LUAD mouse models, and LUAD organoids, correlating with poor clinical prognosis. Furthermore, GTF3C6 was found to promote anchorage-independent proliferation, migration, and invasion of LUAD cells. Mechanistically, KRAS mutation drives GTF3C6 expression through the PI3K pathway, and GTF3C6 knockdown reverses the malignant phenotype of KRAS mutation-driven LUAD cells. Additionally, the FAK pathway emerged as a crucial downstream signaling pathway through which GTF3C6 mediates the malignant phenotype of LUAD. Finally, GTF3C6 knockdown suppresses LUAD organoid formation and inhibits tumor growth in vivo.
Our findings demonstrate that GTF3C6, driven by KRAS mutation, promotes LUAD development by regulating FAK phosphorylation, suggesting its potential as a biomarker and therapeutic target in KRAS mutant-driven LUAD.
Rat sarcoma (RAS) is the most frequently mutated oncogene in human cancer, with Kirsten rat sarcoma (KRAS) being the most commonly mutated RAS isoform. Overall, KRAS accounts for 85% of RAS mutations ...observed in human cancers and is present in 35% of lung adenocarcinomas (LUADs). While the use of targeted therapies and immune checkpoint inhibitors (CPIs) has drastically changed the treatment landscape of advanced non-small-cell lung cancer (NSCLC) in recent years, historic attempts to target KRAS (both direct and indirect approaches) have had little success, and no KRAS-specific targeted therapies have been approved to date for patients in this molecular subset of NSCLC. With the discovery by Ostrem, Shokat, and colleagues of the switch II pocket on the surface of the active and inactive forms of KRAS, we now have an improved understanding of the complex interactions involved in the RAS family of signaling proteins which has led to the development of a number of promising direct KRASG12C inhibitors, such as sotorasib and adagrasib. In previously treated patients with KRASG12C-mutant NSCLC, clinical activity has been shown for both sotorasib and adagrasib monotherapy; these data suggest promising new treatment options are on the horizon. With the stage now set for a new era in the treatment of KRASG12C-mutated NSCLC, many questions remain to be answered in order to further elucidate the mechanisms of resistance, how best to use combination strategies, and if KRASG12C inhibitors will have suitable activity in earlier lines of therapy for patients with advanced/metastatic NSCLC.
•Better understanding of RAS signaling has led to the development of promising directly blocking compounds in KRAS-mutant tumors.•New drug candidates take advantage of the increased knowledge of the KRAS mutation complex and relevant protein structures.•Increasing evidence continues to demonstrate the genomic heterogeneity in KRAS-mutated NSCLC.•Current efforts include understanding and overcoming resistance after treatment with KRASG12C inhibitors.
•CRISP prospectively collected real-world data on advanced NSCLC and KRAS mutations.•Of 1039 patients, 39.5 % had KRAS mutations, 38.9 % of these were KRAS G12C-mutated.•KRAS G12C-mutated advanced ...NSCLC has poor outcome under current standard therapy.•Valuable historical control for upcoming clinical studies on KRAS-inhibitors.
After decades of unsuccessful efforts in inhibiting KRAS, promising clinical data targeting the mutation subtype G12C emerge. Since little is known about outcome with standard treatment of patients with G12C mutated non-small cell lung cancer (NSCLC), we analyzed a large, representative, real-world cohort from Germany.
A total of 1039 patients with advanced KRAS-mutant or -wildtype NSCLC without druggable alterations have been recruited in the prospective, observational registry CRISP from 12/2015 to 06/2019 by 98 centers in Germany. Details on treatment, best response, and outcome were analyzed for patients with KRAS wildtype, G12C, and non-G12C mutations.
Within the study population, 160 (15.4 %) patients presented with KRAS G12C, 251 (24.2 %) with non-G12C mutations, 628 (60.4 %) with KRAS wildtype. High PD-L1 expression (Tumor Proportion Score, TPS > 50 %) was documented for 28.0 %, 43.5 %, and 28.9 % (wildtype, G12C, non-G12C) of the tested patients; 68.8 %, 89.3 %, and 87.7 % of the patients received first-line treatment combined with an immune checkpoint-inhibitor in 2019. TPS > 50 % vs. TPS < 1 % was associated with a significantly decreased risk of mortality in a multivariate Cox model (HR 0.39, 95 % CI 0.26−0.60, p=<0.001). There were no differences in clinical outcome between KRAS wildtype, G12C or non-G12C mutations and KRAS mutational status was not prognostic in the model.
Here we describe the so far largest prospectively recruited cohort of patients with advanced NSCLC and KRAS mutations, with special focus on the G12C mutation. These data constitute an extremely valuable historical control for upcoming clinical studies that employ KRAS inhibitors.
Patient-derived organoids (PDO) are promising tumor avatars that could enable ex vivo drug tests to personalize patients’ treatment in the frame of functional precision oncology (FPM). Yet, clinical ...evidence remain scarce. This study aims to evaluate whether PDO can be implemented in clinical practice to benefit patients with advanced refractory pancreatic adenocarcinoma (PDAC).
During 2021-2022, 87 patients were prospectively enrolled in an IRB-approved protocol. Inclusion criteria were: histologically-confirmed PDAC, tumor site accessible. A panel of 25 approved antitumor therapies (chemogram) was tested and compared to patient responses to assess PDO predictive values and map the drug sensitivity landscape in PDAC.
Fifty-four PDOs were generated from 87 pretreated patients (take-on rate 62%). The main PDO mutations were KRAS (96%), TP53 (88%) and CDKN2A/B (22%), with 91% concordance rate with their tumor of origin. The mean turnaround-time to chemogram was 6.8 weeks. In 91% of cases, ≥1 hit was identified (gemcitabine (n=20/54), docetaxel (n=18/54) and vinorelbine (n=17/54) with a median of 3 hits/patient range:0-12).
Our cohort included 34 evaluable patients with full clinical follow-up. We report a chemogram sensitivity of 83.3% and specificity of 92.9%. The overall-response rate and progression-free survival were higher when patients received a “hit” treatment as compared to patients that received a “non-hit” drug (as part of routine management).
Finally, we leveraged our PDO collection as a platform for drug validation and combo identification. We tested the anti-KRASG12D (MRTX1133), alone or combined, and identified a specific synergy with anti-EGFR therapies in KRASG12D variants.
We report the largest prospective study aiming at implementing PDO-based FPM and identify very robust predictive values in this clinical setting. In a clinically relevant turnaround-time, we identify putative hits for 91% of patients, providing unexpected potential survival benefits in this very aggressive indication. While this remains to be confirmed in interventional precision oncology trials, PDO collection already provide powerful opportunities for drugs and combinatorial treatment development.
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With recent advances proving that effective inhibition of KRAS is possible, there have been significant efforts made to develop inhibitors of specific mutant alleles. Here we describe a detailed ...protocol that employs homogeneous time-resolved fluorescence (HTRF) to identify compounds acting on KRAS signaling in malignant cell lines. This method allows for high-throughput, cell-based screens of large compound libraries for the development of RAS-targeted therapeutics.
•RAS is the most frequently mutated oncogene in human cancers, accounting for approximately 30% of mutations in all human cancers.•Despite playing a distinct role in tumorigenesis, various attempts ...to inhibit K-RAS directly in the past were unsuccessful.•Additionally, inhibiting downstream Kras signaling through approaches such as inhibiting RAF, MEK and ERK have been unsuccessful.•Recently, a binding pocket (S-IIP) has been identified in K-RAS G12C that can be targeted by covalent inhibitors.•The K-RAS G12C mutation is present in about 13% of lung adenocarcinoma and 3% of colorectal cancer cases. Several inhibitors of this specific mutation have been developed, with initial evidence of impressive clinical activity.•Other approaches including, SHP2, SOS1 and eIF4 inhibition, are being evaluated to abrogate tumor growth in K-RAS mutant cells.
RAS is the most frequently mutated oncogene in human cancers, with mutations in about 30% of all cancers. RAS exists in three different isoforms (K-RAS, H-RAS and N-RAS) with high sequence homology. K-RAS is the most commonly mutated RAS isoform. The Ras protein is a membrane bound protein with inherent GTPase activity and is activated by numerous extracellular stimuli, cycling between an inactive (GDP-bound) and active (GTP-bound) form. When bound to GTP, it is switched “on” and activates intracellular signaling pathways, critical for cell proliferation and angiogenesis. Mutated RAS is constitutively activated and persistently turned “on” thereby enhancing downstream signaling and leading to tumorigenesis. Various attempts to inhibit Kras in the past were unsuccessful. Recently, several small molecules (AMG510, MRTX849, JNJ-74699157, and LY3499446) have been developed to specifically target K-RAS G12C. Additionally, various other approaches including, SHP2, SOS1 and eIF4 inhibition, have been utilized to abrogate tumor growth in K-RAS mutant cells, resulting in a renewed interest in this pathway. In this review article, we provide an overview on the role of K-RAS in tumorigenesis, past approaches to inhibiting Kras, and current and future prospects for targeting Kras.
Abstract
Objective
Numerous scattered case studies continue to demonstrate a strong correlation between acquired KRAS mutations and epidermal growth factor receptor-tyrosine kinase inhibitor ...resistance in non-small cell lung cancer. However, the comprehensive understanding of the KRAS pathway following the failure of epidermal growth factor receptor-tyrosine kinase inhibitor therapy remains limited.
Methods
We conducted a retrospective evaluation of the next generation sequencing data from 323 patients with advanced non-small cell lung cancer and EGFR-activating mutations after experiencing progression with epidermal growth factor receptor-tyrosine kinase inhibitor therapy. Our analysis specifically focused on the acquired changes to the KRAS gene.
Results
Among the 323 patients with advanced non-small cell lung cancer and EGFR-activating mutations who experienced resistance to epidermal growth factor receptor-tyrosine kinase inhibitor therapy, 14 individuals (4.3%) developed resistance due to acquired KRAS alterations. Of these 14 patients, 10 cases (71.4%) were due to KRAS missense mutations, 1 case (7.2%) was due to KRAS gene fusion and 3 cases (21.4%) were due to KRAS amplification. Notably, we identified one newly demonstrated KRAS gene fusion (KRAS and LMNTD1), one KRAS G13D and one KRAS K117N. The emergence of acquired KRAS alterations was often accompanied by novel mutations and high tumor mutation burden, with TP53, CNKN2A, PIK3CA, MYC, STK11, CDK4, BRCA2 and ERBB2 being the most frequently observed concurrent mutations. The median progression-free survival and overall survival for the 14 patients were 5.2 and 7.3 months, respectively. Acquired KRAS missense variants were associated with significantly worse progression-free survival compared with other KRAS variant subtypes (P < 0.028).
Conclusions
This study provides significant evidence of the role of acquired KRAS variants in the development of resistance to epidermal growth factor receptor-tyrosine kinase inhibitor therapy. Our results contribute to the growing body of knowledge on the mutational profiles associated with resistance to epidermal growth factor receptor-tyrosine kinase inhibitor treatment. Furthermore, our study highlights the KRAS gene change as a significant mechanism of resistance to epidermal growth factor receptor-tyrosine kinase inhibitor therapy.
The study identified 14 cases showing acquired KRAS alterations associated with resistance to epidermal growth factor receptor-tyrosine kinase inhibitor. These findings contribute to our comprehension of the mutational profiles linked to epidermal growth factor receptor-tyrosine kinase inhibitor resistance.
Ras GTPases are mutated at codons 12, 13, and 61, with different frequencies in KRas, HRas, and NRas and in a cancer-specific manner. The G13D mutant appears in 25% of KRas-driven colorectal cancers, ...while observed only rarely in HRas or NRas. Structures of Ras G13D in the three isoforms show an open active site, with adjustments to the D13 backbone torsion angles and with disconnected switch regions. KRas G13D has unique features that destabilize the nucleotide-binding pocket. In KRas G13D bound to GDP, A59 is placed in the Mg2+ binding site, as in the HRas-SOS complex. Structure and biochemistry are consistent with an intermediate level of KRas G13D bound to GTP, relative to wild-type and KRas G12D, observed in genetically engineered mouse models. The results explain in part the elevated frequency of the G13D mutant in KRas over the other isoforms of Ras.
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•Ras G13D proteins have open active sites with disconnected switches I and II•KRas G13D shows unique destabilization of the nucleotide-binding pocket•KRas G13D has attenuated oncogenic phenotype relative to KRas G12D•KRas G13D and KRas G12D are more sensitive to Erk than to Akt inhibition
Johnson et al. show that conformational states and biochemical properties of the KRas G13D oncogenic mutant in the context of isoform-specific residues unique to KRas lead to destabilization of the active site, consistent with its intermediate phenotype between wild-type KRas and KRas G12D in genetically engineered mice.
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