KRAS Mutant Colorectal Cancer Research Articles

Trastuzumab Deruxtecan in Advanced Solid Tumors With Human Epidermal Growth Factor Receptor 2 Amplification Identified by Plasma Cell-Free DNA Testing: A Multicenter, Single-Arm, Phase II Basket Trial.

HERALD/EPOC1806 was conducted as a multicenter phase II trial assessing trastuzumab deruxtecan (T-DXd) therapy for patients with human epidermal growth factor receptor 2 (HER2)-amplified progressive stage solid tumors detected by cell-free DNA (cfDNA) testing. Patients exhibited advanced solid tumors with HER2 amplification that was identified via next-generation sequencing of cfDNA testing, without the requirement for immunohistochemical HER2 testing. The studied group was administered T-DXd at 5.4 mg/kg once every 3 weeks until onset of disease progression or intolerable toxicity. Overall, 4,734 patients underwent cfDNA testing from December 2019 to January 2022, and 252 demonstrated HER2 amplification. Finally, the study included 62 patients with 16 cancer types with a median baseline plasma HER2 copy number (CN) of 8.55 (range, 2.4-73.9). Confirmed overall response rate (ORR) by investigator assessment was 56.5% (95% CI, 43.3 to 69.0), thus showing a value beyond the 5% threshold. Responses were evaluated for 13 cancer types, including KRAS-mutant colorectal (1/3), PIK3CA-mutant endometrial (5/6), and tissue HER2-negative gastric (1/2) cancers. Plasma HER2 CN above versus below the baseline median value did not differ for impact response; however, clearance of HER2 amplification in cfDNA on cycle 2 day 1 had higher response values compared with persistence. Median progression-free survival and response duration were 7.0 (95% CI, 4.9 to 9.7) and 8.8 (95% CI, 5.8 to 11.2) months, respectively, with the majority of complications being mild to moderate. Interstitial lung diseases were identified in 16 (26%) patients, including 14 patients with grade 1 disease, one patient with grade 2 disease, and one patient with grade 3 disease. T-DXd treatment demonstrated high ORR with durable response in patients with advanced HER2-amplified solid tumors determined with cfDNA testing.

Microbubble Enhanced Delivery of Vitamin C for Treatment of Colorectal Cancer.

During chemotherapy treatment for cancer, often only a fraction of the administered dose reaches the tumor site, with the remaining drug spreading throughout the body, producing unwanted side-effects and restricting how much drug can be safely administered. A potential solution to reduce this problem is the use of microbubbles. The interaction between microbubbles and ultrasound generates pores in the tumor cells, permitting enhanced drug uptake. This study investigates the delivery of the ascorbic acid derivative, palmitoyl ascorbate, to KRAS-mutated colorectal cancer cells in vitro. Ultrasound-triggered microbubbles enhanced the efficacy of liposomal palmitoyl ascorbate treatments by 1.7- and 2.2-fold in LS174T and HCT116 CRC cell lines, respectively. This enhancement was achieved without increasing the drug dosage, and the therapeutic effect was shown to be localized to the area that received the ultrasound pulse, aiding in the reduction of off-site toxicity.

TRIM21 induces selective autophagic degradation of c-Myc and sensitizes regorafenib therapy in colorectal cancer

Kirsten rat sarcoma virus (KRAS) mutation is associated with malignant tumor transformation and drug resistance. However, the development of clinically effective targeted therapies for KRAS-mutant cancer has proven to be a formidable challenge. Here, we report that tripartite motif-containing protein 21 (TRIM21) functions as a target of extracellular signal-regulated kinase 2 (ERK2) in KRAS-mutant colorectal cancer (CRC), contributing to regorafenib therapy resistance. Mechanistically, TRIM21 directly interacts with and ubiquitinates v-myc avian myelocytomatosis viral oncogene homolog (c-Myc) at lysine 148 (K148) via K63-linkage, enabling c-Myc to be targeted to the autophagy machinery for degradation, ultimately resulting in the downregulation of enolase 2 expression and inhibition of glycolysis. However, mutant KRAS (KRAS/MT)-driven mitogen-activated protein kinase (MAPK) signaling leads to the phosphorylation of TRIM21 (p-TRIM21) at Threonine 396 (T396) by ERK2, disrupting the interaction between TRIM21 and c-Myc and thereby preventing c-Myc from targeting autophagy for degradation. This enhances glycolysis and contributes to regorafenib resistance. Clinically, high p-TRIM21 (T396) is associated with an unfavorable prognosis. Targeting TRIM21 to disrupt KRAS/MT-driven phosphorylation using the antidepressant vilazodone shows potential for enhancing the efficacy of regorafenib in treating KRAS-mutant CRC in preclinical models. These findings are instrumental for KRAS-mutant CRC treatment aiming at activating TRIM21-mediated selective autophagic degradation of c-Myc.

A novel platform for mutation detection in colorectal cancer using a PNA-LNA molecular switch

Detection of KRAS mutation in colorectal cancer (CRC) is important in the prediction of response to target therapy. The study aims to develop a novel mutation detection platform called the “PNA-LNA molecular switch” for the detection of KRAS mutation in CRC. We employed the enhanced binding specificity of peptide nucleic acid (PNA) and locked nucleic acid (LNA) in conjunction with a loop-mediated isothermal amplification (LAMP) approach to identify the mutation status of KRAS oncogene codon 12 (c.35G>T/G12V and c.35G>A/G12D) using synthetic oligonucleotides and colon cancer cell lines (Caco-2 and SW480). This method specifically blocked the amplification of the wild-type sequences while substantially amplifying the mutated ones, which was visualized by both colorimetric and fluorescence assays. We then checked the mutation profile of KRAS codon 12 in the DNA derived from tumor tissue samples (number of samples, n = 30) and circulating tumor cells (n = 24) from CRC patients. Finally, we validated the results by comparing them with the data obtained from DNA sequencing of colon tumors (n = 21) of the same CRC patients. This method showed excellent sensitivity (1 DNA copy/μl), reproducibility [relative standard deviation (%RSD) < 5%, for n = 3], and linear dynamic range (1 ag/μl-10 pg/μl, R2 = 0.94). This platform is significantly faster, relatively cheaper, has superior sensitivity and specificity, and does not require any high-end equipment. To conclude, this method has the potential to be translated into clinical settings for the detection of mutations in diverse diseases and conditions.

Epigenetic and Oncogenic Inhibitors Cooperatively Drive Differentiation and Kill KRAS-Mutant Colorectal Cancers.

Combined EZH2 and RAS pathway inhibitors kill KRAS-mutant colorectal cancer cells and promote durable tumor regression in vivo. These agents function by cooperatively suppressing the WNT pathway, driving differentiation, and epigenetically reprogramming cells to permit the induction of apoptotic signals, which then kill these more differentiated tumor cells.

CircRAPGEF5 acts as a modulator of RAS/RAF/MEK/ERK signaling during colorectal carcinogenesis

Mutations in oncogenes such as KRAS, NRAS and BRAF promote the growth and survival of tumors, while excessive RAS/RAF/MEK/ERK activation inhibits tumor growth. In this study we examined the precise regulatory machinery that maintains a moderate RAS/RAF/MEK/ERK pathway activation during CRC. Here, using bioinformatic analysis, transcriptomic profiling, gene silencing and cellular assays we discovered that a circular RNA, circRAPGEF5, is significantly upregulated in KRAS mutant colorectal cancer (CRC) cells. CircRAPGEF5 suppressed mutant and constitutively activated KRAS and the expression of the death receptor TNFRSF10A. Silencing of circRAPGEF5-induced RAS/RAF/MEK/ERK signaling hyperactivation and apoptosis in CRC cells suggesting that an upregulation of circRAPEF5 may suppress the expression of TNFRSF10A and aid CRC progression by preventing apoptosis, while the direct interactions between circRAPGEF5 and elements of the RAS/RAF/MEK/ERK pathway was not identified, which nevertheless can be the basis for future research. Moreover, EIF4A3, was observed to share a similar expression pattern with circRAPEF5 and demonstrated to be a major controller of circRAPGEF5 via the promotion of circRAPGEF5 circularization and its silencing reduced circRAPGEF5 levels. Taken together, our findings reveal a mechanism of accurate RAS/RAF/MEK/ERK signaling regulation during CRC progression maintained by upregulation of circRAPGEF5 which may be a plausible target for future clinical applications that seek to induce CRC cell apoptosis via the RAS/RAF/MEK/ERK signaling pathway.

Asparagine synthetase and G-protein coupled estrogen receptor are critical responders to nutrient supply in KRAS mutant colorectal cancer.

Survival differences exist in colorectal cancer (CRC) patients by sex and disease stage. However, the potential molecular mechanism(s) are not well understood. Here we show that asparagine synthetase (ASNS) and G protein-coupled estrogen receptor-1 (GPER1) are critical sensors of nutrient depletion and linked to poorer outcomes for females with CRC. Using a 3D spheroid model of isogenic SW48 KRAS wild-type (WT) and G12A mutant (MT) cells grown under a restricted nutrient supply, we found that glutamine depletion inhibited cell growth in both cell lines, whereas ASNS and GPER1 expression were upregulated in KRAS MT versus WT. Estradiol decreased growth in KRAS WT but had no effect on MT cells. Selective GPER1 and ASNS inhibitors suppressed cell proliferation with increased caspase-3 activity of MT cells under glutamine depletion condition particularly in the presence of estradiol. In a clinical colon cancer cohort fromThe Cancer Genome Atlas, both high GPER1 and ASNS expression were associated with poorer overall survival for females only in advanced stage tumors. These results suggest KRAS MT cells have mechanisms in place that respond to decreased nutrient supply, typically observed in advanced tumors, by increasing the expression of ASNS and GPER1 to drive cell growth. Furthermore, KRAS MT cells are resistant to the protective effects of estradiol under nutrient deplete conditions. The findings indicate that GPER1 and ASNS expression, along withthe interaction between nutrient supply and KRAS mutations shed additional light on the mechanisms underlyingsex differences in metabolism and growth in CRC, and have clinical implications in the precision management of KRAS mutant CRC.

Targeting Smurf1 to block PDK1-Akt signaling in KRAS-mutated colorectal cancer.

The phosphoinositide 3-kinase (PI3K)-Akt axis is one of the most frequently activated pathways and is demonstrated as a therapeutic target in Kirsten rat sarcoma viral oncogene homolog (KRAS)-mutated colorectal cancer (CRC). Targeting the PI3K-Akt pathway has been a challenging undertaking through the decades. Here we unveiled an essential role of E3 ligase SMAD ubiquitylation regulatory factor 1 (Smurf1)-mediated phosphoinositide-dependent protein kinase 1 (PDK1) neddylation in PI3K-Akt signaling and tumorigenesis. Upon growth factor stimulation, Smurf1 immediately triggers PDK1 neddylation and the poly-neural precursor cell expressed developmentally downregulated protein 8 (poly-Nedd8) chains recruit methyltransferase SET domain bifurcated histone lysine methyltransferase 1 (SETDB1). The cytoplasmic complex of PDK1 assembled with Smurf1 and SETDB1 (cCOMPASS) consisting of PDK1, Smurf1 and SETDB1 directs Akt membrane attachment and T308 phosphorylation. Smurf1 deficiency dramatically reduces CRC tumorigenesis in a genetic mouse model. Furthermore, we developed a highly selective Smurf1 degrader, Smurf1-antagonizing repressor of tumor 1, which exhibits efficient PDK1-Akt blockade and potent tumor suppression alone or combined with PDK1 inhibitor in KRAS-mutated CRC. The findings presented here unveil previously unrecognized roles of PDK1 neddylation and offer a potential strategy for targeting the PI3K-Akt pathway and KRAS mutant cancer therapy.

Identification and verification of KEAP1‐related genes and targets regulated by potential ingredients in KRAS mutant colorectal cancer

AbstractAs one of the most prevalent tumors, colorectal cancer (CRC) owns complex pathogenesis and the high recurrence rate significantly influence the prognosis of patients with KRAS mutant CRC, to discovery the crosstalk among KEAP1‐NFE2L2 and oncogenic KRAS as the potential prognostic biomarkers in CRC, which might be used to develop novel and effective therapeutics. By using bioinformatics analysis, we explored and identified key genes as the predicted targets in the crosstalk among KEAP1 oncogenic signatures of KRAS mutation that were linked with development, metastasis, and poor prognosis in CRC. We further investigated the correlations between the clinical characteristics and expressions of prognostic genes among the KRAS and KEAP1‐related key hub genes in CRC, which as predicted targets to find the potential herbal ingredients in HERB database, further to verify the active herbal ingredients could regulate the key targets that related to KEAP1‐NFE2L2 in KRAS mutant CRC. The newest TCGA data reveals that the mutation of KRAS is found in 44% of CRC patients. In total, 28 genes were identified as differentially expressed genes (DEGs), and the hub genes such as CDKN2A, SPP1, FOS, BCL2L11, and HPSE were verified. Results indicated that key genes (SOX9, SPP1) significant correlation with the target prediction of the active herbal ingredients by molecular docking analysis. Furthermore, KEAP1, NFE2L2, SOX9 expression were decreased significantly with the treatment of potential ingredients. Furthermore, cyclopamine could enhance the sensitivity of HCT116 cells, downregulated the expression of SPP1, and induced activation of KEAP1‐NFE2L2 pathway, which cell death are characteristic features of apoptosis, and enhanced anticancer effect. Therefore, KEAP1‐related genes might be important oncogenic signatures in KRAS mutant CRC cells and cyclopamine was identified as a potential ingredient and regulated the predict targets of SOX9 and SPP1, may be expand the efficacy and range of novel and effective therapeutics.

Erlotinib Treatment in Colorectal Cancer Suppresses Autophagy Based on KRAS Mutation.

The KRAS gene is mutated in approximately 45% of colorectal cancer patients. There are currently very few targeted treatments or therapies equipped to directly inhibit KRAS due to its unusual structural intricacies. Erlotinib, an EGFR inhibitor, has previously been demonstrated to reduce cell viability by inducing autophagy in lung cancer cell lines with varying EGFR mutations. In contrast to lung cancer cells, evidence is provided herein for the first time that erlotinib treatment in colorectal cancer (CRC) cell lines reduces autophagy and still results in decreased cell viability. However, the effects of erlotinib in CRC cell lines containing a wildtype KRAS gene were different than in cells carrying a mutant KRAS gene. We show that there is significantly more downregulation of autophagy in KRAS mutant CRC cells compared to KRAS wildtype cells, both at transcriptional and translational levels, suggesting that the KRAS mutation is advantageous for cancer growth, even in the presence of erlotinib. Cell viability results determined that KRAS wildtype CRC cells had significantly more cell death compared to KRAS mutant cells. Using patient mRNA datasets, we showed that there was a significant correlation between the presence of the KRAS mutation and the expression of autophagy proteins. Additionally, through molecular dynamics simulations, we develop a blueprint for KRAS and autophagy protein interaction and the impact of the KRAS mutation on autophagy protein regulation. Overall, this is the first report of erlotinib treatment in CRC cells that assesses autophagy, and we demonstrate that autophagy activity is downregulated in these cells. This effect is not only greater in cells carrying a KRAS mutation compared to wildtype cells, but the KRAS mutant cells also have increased cell viability compared to wildtype cells. We hypothesize that the difference in cell viability and autophagy expression between KRAS mutant and KRAS wildtype cells after treatment with erlotinib can be of therapeutic value to treat CRC patients carrying KRAS mutations.

A first-in-class selective inhibitor of EGFR and PI3K offers a single-molecule approach to targeting adaptive resistance

Despite tremendous progress in precision oncology, adaptive resistance mechanisms limit the long-term effectiveness of molecularly targeted agents. Here we evaluated the pharmacological profile of MTX-531 that was computationally designed to selectively target two key resistance drivers, epidermal growth factor receptor and phosphatidylinositol 3-OH kinase (PI3K). MTX-531 exhibits low-nanomolar potency against both targets with a high degree of specificity predicted by cocrystal structural analyses. MTX-531 monotherapy uniformly resulted in tumor regressions of squamous head and neck patient-derived xenograft (PDX) models. The combination of MTX-531 with mitogen-activated protein kinase kinase or KRAS-G12C inhibitors led to durable regressions of BRAF-mutant or KRAS-mutant colorectal cancer PDX models, resulting in striking increases in median survival. MTX-531 is exceptionally well tolerated in mice and uniquely does not lead to the hyperglycemia commonly seen with PI3K inhibitors. Here, we show that MTX-531 acts as a weak agonist of peroxisome proliferator-activated receptor-γ, an attribute that likely mitigates hyperglycemia induced by PI3K inhibition. This unique feature of MTX-531 confers a favorable therapeutic index not typically seen with PI3K inhibitors.

Improved Biological Impacts of Anti-EGFR Monoclonal Antibody in KRAS-Mutant Colorectal Cancer Cells by Silica-Coated Magnetic Nanoparticle Conjugation

Background: The therapeutic potential of epidermal growth factor receptor (EGFR) targeting in colorectal cancer (CRC) is hindered by the presence of KRAS codon 12 activating mutations, prevalent in approximately 25% of advanced CRC cases. This study investigates the role of reactive oxygen species (ROS) in conferring resistance to anti-EGFR monoclonal antibodies in KRAS mutant CRC cells, focusing on ROS-mediated apoptosis induction using cetuximab-PEGylated silica-coated magnetic nanoparticles (MNPs). Methods: MNPs were synthesized and surface-coated with silica, followed by functionalization and stabilization with polyethylene glycol (PEG). Cetuximab (Cet) was covalently conjugated to generate EMNP-PEG-Cet. Structural and compositional analyses were performed using scanning electron microscopy (SEM), dynamic light scattering (DLS), UV-vis spectroscopy, and Fourier transform infrared (FTIR) analysis. Apoptosis induction, chromatin condensation, and ROS production were evaluated in KRAS mutant SW-480 CRC cells. Results: Successful synthesis of EMNP-PEG-Cet was confirmed, revealing a particle size of 67 nm and a surface charge of -8.3 mV. The conjugate exhibited significant cytotoxicity against CRC cells, with notable apoptosis induction and ROS generation in EGFR-positive/KRAS mutant SW-480 cells, surpassing the effects observed with bare Cet and EMNP-PEG controls. The nuclear factor erythroid 2-related factor 2/Kelch-like ECH-related protein 1 (Nrf2-Kaep1) gene expression analysis by real-time PCR showed that cells treated with EMNP-PEG-Cet exhibited a noteworthy decrease in Nrf2 expression and a simultaneous increase in Keap1 expression compared to those treated with free Cet. Conclusion: These findings highlight the potential of ROS-mediated apoptosis induction to enhance the cytotoxicity of Cet in EGFR-positive/KRAS mutant CRC cells, offering new avenues for overcoming drug resistance mechanisms in metastatic CRC.

Selective PI3Kδ inhibitor TYM-3-98 suppresses AKT/mTOR/SREBP1-mediated lipogenesis and promotes ferroptosis in KRAS-mutant colorectal cancer

Colorectal cancer (CRC) is one of the most common tumors of the digestive system worldwide. KRAS mutations limit the use of anti-EGFR antibodies in combination with chemotherapy for the treatment of CRC. Therefore, novel targeted therapies are needed to overcome the KRAS-induced oncogenesis. Recent evidence suggests that inhibition of PI3K led to ferroptosis, a nonapoptotic cell death closely related to KRAS-mutant cells. Here, we showed that a selective PI3Kδ inhibitor TYM-3–98 can suppress the AKT/mTOR signaling and activate the ferroptosis pathway in KRAS-mutant CRC cells in a concentration-dependent manner. This was evidenced by the lipid peroxidation, iron accumulation, and depletion of GSH. Moreover, the overexpression of the sterol regulatory element-binding protein 1 (SREBP1), a downstream transcription factor regulating lipid metabolism, conferred CRC cells greater resistance to ferroptosis induced by TYM-3–98. In addition, the effect of TYM-3–98 was confirmed in a xenograft mouse model, which demonstrated significant tumor suppression without obvious hepatoxicity or renal toxicity. Taken together, our work demonstrated that the induction of ferroptosis contributed to the PI3Kδ inhibitor-induced cell death via the suppression of AKT/mTOR/SREBP1-mediated lipogenesis, thus displaying a promising therapeutic effect of TYM-3–98 in CRC treatment.

A machine learning and drug repurposing approach to target ferroptosis in colorectal cancer stratified by sex and KRAS.

The landscape of sex differences in Colorectal Cancer (CRC) has not been well characterized with respect to the mechanisms of action for oncogenes such as KRAS. However, our recent study showed that tumors from male patients with KRAS mutations have decreased iron-dependent cell death called ferroptosis. Building on these findings, we further examined ferroptosis in CRC, considering both sex of the patient and KRAS mutations, using public databases and our in-house CRC tumor cohort. Through subsampling inference and variable importance analysis (VIMP), we identified significant differences in gene expression between KRAS mutant and wild type tumors from male patients. These genes suppress (e.g., SLC7A11 ) or drive (e.g., SLC1A5 ) ferroptosis, and these findings were further validated with Gaussian mixed models. Furthermore, we explored the prognostic value of ferroptosis regulating genes and discovered sex- and KRAS-specific differences at both the transcriptional and metabolic levels by random survival forest with backward elimination algorithm (RSF-BE). Of note, genes and metabolites involved in arginine synthesis and glutathione metabolism were uniquely associated with prognosis in tumors from males with KRAS mutations. Additionally, drug repurposing is becoming popular due to the high costs, attrition rates, and slow pace of new drug development, offering a way to treat common and rare diseases more efficiently. Furthermore, increasing evidence has shown that ferroptosis inhibition or induction can improve drug sensitivity or overcome chemotherapy drug resistance. Therefore, we investigated the correlation between gene expression, metabolite levels, and drug sensitivity across all CRC primary tumor cell lines using data from the Genomics of Drug Sensitivity in Cancer (GDSC) resource. We observed that ferroptosis suppressor genes such as DHODH , GCH1 , and AIFM2 in KRAS mutant CRC cell lines were resistant to cisplatin and paclitaxel, underscoring why these drugs are not effective for these patients. The comprehensive map generated here provides valuable biological insights for future investigations, and the findings are supported by rigorous analysis of large-scale publicly available data and our in-house cohort. The study also emphasizes the potential application of VIMP, Gaussian mixed models, and RSF-BE models in the multi-omics research community. In conclusion, this comprehensive approach opens doors for leveraging precision molecular feature analysis and drug repurposing possibilities in KRAS mutant CRC.

Aberrant Expression of Sprouty2 In Human Colon Cancer

Purpose: The study investigates the role of Sprouty2 (SPRY2) in colorectal cancer (CRC) cell function. It found that SPRY2 inhibits the RAS/MAPK/ERK pathway and promotes cancer invasion in KRAS-WT CRC. However, it did not significantly alter p-ERK levels, cell proliferation, or invasion in KRAS-mutant CRCs. High SPRY2 expression was associated with shorter cancer-specific survival in both KRAS-WT and KRAS-mutant CRC patients. The study suggests that SPRY2 may promote invasion and progression in both types of CRC. Methods: The gene expression data were retrieved from Gene Expression Omnibus (GEO). Fold change, p.value t-test and David Functional analysis, hierarchical clustering was performed. Results: In this study, we identified altered genes involved in SPRY2 mutation in the colon and the relevant pathways to understand whether the SPRY2 mutation changes cancer progression. 4 genes of 5 genes were downregulated following the mutation in colon cancer cells. We identified a network between these genes and pathways they belong to. Pathway analysis showed that these genes are mostly associated with cancer cell proliferation. Conclusion: MAL2, ESRP1, CDH3, CXCL14 and CDH1 genes were found to be associated with in SPRY2 mutation in colon cancer pathogenesis. Almost all these genes are effective in the proliferation of cancer cells, especially during the SPRY2 mutation process. Therefore, it is hypothesized that downregulation or upregulation of these genes may affect colon cancer pathogenesis by reducing cell proliferation. And it is predicted that SPRY2 mutation may be an important factor for colon cancer.

PDP1 promotes KRAS mutant colorectal cancer progression by serving as a scaffold for BRAF and MEK1

The oncogenic role of KRAS in colorectal cancer (CRC) progression is well-established. Despite this, identifying effective therapeutic targets for KRAS-mutated CRC remains a significant challenge. This study identifies pyruvate dehydrogenase phosphatase catalytic subunit 1 (PDP1) as a previously unrecognized yet crucial regulator in the progression of KRAS mutant CRC. A substantial upregulation of PDP1 expression is observed in KRAS mutant CRC cells and tissues compared to wild-type KRAS samples, which correlates with poorer prognosis. Functional experiments elucidate that PDP1 accelerates the malignance of KRAS mutant CRC cells, both in vitro and in vivo. Mechanistically, PDP1 acts as a scaffold, enhancing BRAF and MEK1 interaction and activating the MAPK signaling, thereby promoting CRC progression. Additionally, transcription factor KLF5 is identified as the key regulator for PDP1 upregulation in KRAS mutant CRC. Crucially, targeting PDP1 combined with MAPK inhibitors exhibits an obvious inhibitory effect on KRAS mutant CRC. Overall, PDP1 is underscored as a vital oncogenic driver and promising therapeutic target for KRAS mutant CRC.

134P Rate and clinical implications of uncommon KRAS mutations in colorectal cancer

134P Rate and clinical implications of uncommon KRAS mutations in colorectal cancer

A phase 1, first-in-human, open-label study evaluating the safety, tolerability, pharmacokinetics, and efficacy of TT125-802 in patients with advanced solid tumors.

TPS3171 Background: TT125-802 is a selective, potent, orally bioavailable small molecule inhibitor of the bromodomain of CBP and p300, two highly homologues lysine acetyltransferases. CBP/p300 act as transcriptional co-activators with multiple domains and functions, including well-documented roles in cell cycle regulation and several critical tumorigenic pathways (1-3). TT125-802 has shown mono-therapy efficacy in preclinical models of castration-resistant prostate cancer, KRAS-mutated colorectal and non-small cell lung cancer (4,5). Furthermore, TT125-802 is capable to interfere with transcriptional resistance mechanisms limiting targeted therapies (6) which will be explored clinically upon determination of a safe, well-tolerated, and biologically active single-agent dose. Methods: This study aims to establish the safety, tolerability, and pharmacokinetic profile of TT125-802. The maximum tolerated dose/recommended dose for expansion (MTD/RDE) of repeat daily dosing for TT125-802 monotherapy will be determined in subjects with advanced solid tumors in a sequential escalating cohorts design, (1 cycle = 21 days) using the Bayesian Logistics Regression Model (BLRM) with sentinel patients (2-day window for first patient enrolled in each cohort). Cohorts will consist of 3 to 6 subjects who will be followed over a dose-limiting toxicity (DLT) period of at least 21 days. TT125-802 will be administered orally once daily; additional schedules may be evaluated. Dose escalation is planned to follow two-fold increments. It may be adapted upon dose level revision and guided by pharmacokinetic analysis. Additional subjects (up to 6) may be enrolled in at least two monotherapy cohorts deemed safe and tolerable to optimize the recommended phase 2 dose (RP2D). Up to a total of 20 additional subjects may be enrolled. Translational/pharmacodynamic endpoints: Exploratory endpoints will provide proof-of-principle and early biomarker data for CBP/p300 inhibition. These analyses will include: 1. Single-cell gene expression evaluation of peripheral blood mononuclear cells (PBMCs) at multiple time points, 2. anagen hair bulb bulk RNAseq analysis, and 3. paired tumor biopsies will be analyzed with single-cell RNA sequencing. Together, these investigations are expected to support optimal dose determination. Additionally, circulating tumor DNA might be evaluated to define molecular responses. Outlook: The recommended phase 2 dose will be used further to explore the efficacy of TT125-802 as monotherapy. TT125-802 will be evaluated with targeted therapies (for example, KRASG12C/D, BRAF, EGFR, etc., inhibitors) to exploit the blocking of transcriptional escape mechanisms driven by CBP/p300. 1. Iyer, 2007. 2. Dutta, 2016. 3. Attar, 2017. 4. AACR2023 posters #6268. 5. AACR poster #3907. 6. AACR2023 poster #3907. Clinical trial information: 2022-500849-24-00 .

A dual gene combination therapy approach by KRAS-G12V gene editing and SLC25A22 gene silencing for KRAS-mutant colorectal cancer

KRAS gene is mutated in 40% of colorectal cancers (CRC), which induces malignant proliferation by regulating cellular nutrient metabolism and biosynthesis. It has been found that malignant proliferation of KRAS-mutant colorectal cancer relies on the upregulation of SLC25A22 protein expression, suggesting that inhibition the expression of both KRAS and SLC25A22 is a potential CRC therapeutics. Stably knocking down the oncogenic KRAS-G12V gene can achieve long-term gene therapy effects, while transient downregulation of SLC25A22, a normal functional gene most of the time, is preferred to kill tumor cells and minimize the side impact on normal cells. Here, two lipid nanoparticles (LNP) were designed to encapsulate KRAS-G12V CRISPR/Cas9 gene editing plasmids (pKRAS-LNPs) and SLC25A22 siRNA (siSLC-LNPs), respectively. Therapeutic effects of both nanoparticles alone and in combination on KRAS-G12V mutant colorectal cancer cells in vitro were first examined. The result showed that delivery of pKRAS-LNPs or siSLC-LNPs alone could effectively achieve KRAS-G12V gene editing or SLC25A22 gene silencing and inhibit tumor cell proliferation, while co-delivery of both LNPs could achieve stronger inhibition of tumor cell proliferation by inducing stronger apoptosis. Furthermore, we found that co-delivery of pKRAS-LNPs and siSLC-LNPs induced stronger apoptosis and cell proliferation inhibition compared to pKRAS&siSLC-LNPs that were constructed by pre-mixing pKRAS and siSLC and then encapsulating them. Finally, we validated that co-delivery of pKRAS-LNPs and siSLC-LNPs can achieve KRAS-G12V colorectal cancer treatment in vivo with a tumor inhibition rate of 61.15%. In summary, the delivery vectors constructed for nucleic acids targeting KRAS and SLC25A22 achieved therapeutic targeting of KRAS-G12V colorectal cancer in vitro and in vivo.

Inhibition of PRMT5-mediated regulation of DKK1 sensitizes colorectal cancer cells to chemotherapy

The Dickkopf family proteins (DKKs) are strong Wnt signaling antagonists that play a significant role in colorectal cancer (CRC) development and progression. Recent work has shown that DKKs, mainly DKK1, are associated with the induction of chemoresistance in CRC and that DKK1 expression in cancer cells correlates with that of protein arginine N-methyltransferase 5 (PRMT5). This points to the presence of a regulatory loop between DKK1 and PRMT5. Herein, we addressed the question of whether PRMT5 contributes to DKK1 expression in CRC and hence CRC chemoresistance. Both in silico and in vitro approaches were used to explore the relationship between PRMT5 and different DKK members. Our data demonstrated that DKK1 expression is significantly upregulated in CRC clinical samples, KRAS-mutated CRC in particular and that the levels of DKK1 positively correlate with PRMT5 activation. Chromatin immunoprecipitation (ChIP) data indicated a possible epigenetic role of PRMT5 in regulating DKK1, possibly through the symmetric dimethylation of H3R8. Knockdown of DKK1 or treatment with the PRMT5 inhibitor CMP5 in combination with doxorubicin yielded a synergistic anti-tumor effect in KRAS mutant, but not KRAS wild-type, CRC cells. These findings suggest that PRMT5 regulates DKK1 expression in CRC and that inhibition of PRMT5 modulates DKK1 expression in such a way that reduces CRC cell growth.