KRAS Mutant Colorectal Cancer Research Articles

Identification of KRAS mutation-associated gut microbiota in colorectal cancer and construction of predictive machine learning model.

Gut microbiota has demonstrated an increasingly important role in the onset and development of colorectal cancer (CRC). Nonetheless, the association between gut microbiota and KRAS mutation in CRC remains enigmatic. We conducted 16S rRNA sequencing on stool samples from 94 CRC patients and employed the linear discriminant analysis effect size algorithm to identify distinct gut microbiota between KRAS mutant and KRAS wild-type CRC patients. Transcriptome sequencing data from nine CRC patients were transformed into a matrix of immune infiltrating cells, which was then utilized to explore KRAS mutation-associated biological functions, including Gene Ontology items and Kyoto Encyclopedia of Genes and Genomes pathways. Subsequently, we analyzed the correlations among these KRAS mutation-associated gut microbiota, host immunity, and KRAS mutation-associated biological functions. At last, we developed a predictive random forest (RF) machine learning model to predict the KRAS mutation status in CRC patients, based on the gut microbiota associated with KRAS mutation. We identified a total of 26 differential gut microbiota between both groups. Intriguingly, a significant positive correlation was observed between Bifidobacterium spp. and mast cells, as well as between Bifidobacterium longum and chemokine receptor CX3CR1. Additionally, we also observed a notable negative correlation between Bifidobacterium and GOMF:proteasome binding. The RF model constructed using the KRAS mutation-associated gut microbiota demonstrated qualified efficacy in predicting the KRAS phenotype in CRC. Our study ascertained the presence of 26 KRAS mutation-associated gut microbiota in CRC and speculated that Bifidobacterium may exert an essential role in preventing CRC progression, which appeared to correlate with the upregulation of mast cells and CX3CR1 expression, as well as the downregulation of GOMF:proteasome binding. Furthermore, the RF model constructed on the basis of KRAS mutation-associated gut microbiota exhibited substantial potential in predicting KRAS mutation status in CRC patients.IMPORTANCEGut microbiota has emerged as an essential player in the onset and development of colorectal cancer (CRC). However, the relationship between gut microbiota and KRAS mutation in CRC remains elusive. Our study not only identified a total of 26 gut microbiota associated with KRAS mutation in CRC but also unveiled their significant correlations with tumor-infiltrating immune cells, immune-related genes, and biological pathways (Gene Ontology items and Kyoto Encyclopedia of Genes and Genomes pathways). We speculated that Bifidobacterium may play a crucial role in impeding CRC progression, potentially linked to the upregulation of mast cells and CX3CR1 expression, as well as the downregulation of GOMF:Proteasome binding. Furthermore, based on the KRAS mutation-associated gut microbiota, the RF model exhibited promising potential in the prediction of KRAS mutation status for CRC patients. Overall, the findings of our study offered fresh insights into microbiological research and clinical prediction of KRAS mutation status for CRC patients.

Abstract 2031: A phase 1b/2 clinical study of onvansertib in combination with FOLFIRI/bevacizumab revealed a new role of PLK1 in regulating the hypoxia pathway in KRAS-mutant colorectal cancer

Abstract Background: Onvansertib (Onv) is an oral, small molecule, selective PLK1 kinase inhibitor that demonstrated clinical activity at tolerated drug exposures in combination with FOLFIRI/Bevacizumab (Bev) in the 2nd-line treatment of mutated KRAS (mKRAS) metastatic colorectal cancer (mCRC) (Lenz, JCO, 2022). Here we explored biomarkers of response to the combination therapy and their associated biology. Methods: In a Phase 1b/2 study, mKRAS mCRC patients with prior exposure to oxaliplatin (with or without Bev) were treated with Onv (Days 1-5 and 15-19) in combination with FOLFIRI/Bev (Days 1 and 15) of each 28-day cycle (NCT03829410). Efficacy endpoints included objective response rate (ORR, RECIST v1.1), progression-free survival (PFS) and duration of response (DoR). Preclinically, the combination of Onv and Bev was tested in 3 mKRAS CRC xenograft models. The role of PLK1 in hypoxia was assessed through protein and RNA analyses of mKRAS CRC cell lines exposed to low oxygen levels and treated with Onv. Results: As of 25-AUG-2023, 66 patients were evaluable for efficacy in the Phase 1b/2 and ORR of Onv + FOLFIRI/Bev was 28.8%. Patients had a median PFS of 9.8 months [95%CI: 7.6, 12.6] and median DoR of 11.7 months [95%CI: 9.0, NR]. An analysis of baseline characteristics revealed that patients not exposed to Bev in the 1st-line setting (Bev-naïve patients, n=15) achieved superior clinical benefit compared to Bev-exposed patients (n=51). Bev-naïve patients had significantly higher ORR (73.3% versus 15.7%, p<0.0001) and longer median PFS (14.9 months [95%CI: 10.5, NR] versus 7.8 months [95%CI: 5.6, 9.8], p=0.0013) than Bev-exposed patients. This data prompted us to assess the effect of Onv+Bev in mKRAS CRC xenograft models. Onv+Bev significantly reduced tumor growth in the 3 xenograft models tested. The combination resulted in a greater decrease in tumor vascularization and tumor cell proliferation, and a corresponding increase in apoptosis, compared to either monotherapy. Further, the effect of Onv on the hypoxia pathway was assessed in mKRAS CRC cell lines. Our findings indicated that under low oxygen levels, Onv inhibited the hypoxia pathway by reducing the expression of the hypoxia-inducible factor 1-alpha (HIF1α) protein, and the mRNA expression of its downstream targets. Conclusions: Onv + FOLFIRI/Bev resulted in greater clinical benefit in Bev- naïve than Bev-exposed mKRAS CRC patients. Preclinical studies revealed synergistic effect of Onv and Bev in mKRAS CRC xenografts, and a new function of PLK1 in modulating the hypoxia pathway through the regulation of HIF1α. Collectively, this data supports a crosstalk between PLK1 and angiogenesis, and further exploration of Onv + FOLFIRI/Bev therapy in Bev-naïve mCRC patients with KRAS mutation. Citation Format: Maya Ridinger, Anju Karki, Ramanand A. Subramanian, Errin Samuelsz, Divora Yemane, Roy Kim, Chu-Chiao Wu, Fairooz F. Kabbinavar, Tod Smeal, Heinz-Josef Lenz. A phase 1b/2 clinical study of onvansertib in combination with FOLFIRI/bevacizumab revealed a new role of PLK1 in regulating the hypoxia pathway in KRAS-mutant colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2031.

Abstract 7150: Molecular insights into the oncogenic influence between mutant HER3, mutant KRAS, and their synergistic interplay in colorectal cancer pathogenesis

Abstract Colorectal cancer (CRC) is a disease of the colon and rectum that will claim about 52,550 American lives in 2023. In recent years, more attention has been paid to HER2 and HER3’s roles in colorectal cancers, as they may cause resistance to targeted therapies. We are investigating the role of naturally co-occurring HER3 and KRAS mutations in colorectal cancer, as about 6% of all colorectal cancers contain a HER3 mutation and 41% contain a KRAS mutation. We have observed that there is a statistically significant co-occurrence of HER3 and KRAS mutations in CRCs while there is mutual exclusivity with mutations in EGFR or HER4 and mutant KRAS in CRC examining 6791 samples from 17 studies. There is a tendency for co-occurrence with HER2 and KRAS mutations that is not statistically significant in these CRC tumor samples. We have found that genetic knockdown of both KRAS and HER3 with siRNA targeting KRAS and HER3 in the CRC cell line SNU-407 (HER3V104M, KRASG12D) results in a statistical reduction in cell proliferation in comparison to genetic knockdown with only KRAS or HER3. Using the SW620 CRC cell line (HER3WT, KRASG12V) as a comparison, we have observed that knocking down HER3 using siRNA had no effect on cell proliferation whereas KRAS knockdown reduced proliferation and the combination showed no statistical difference compared to knocking down only KRAS. Additionally, we have found that there is a striking increase in total HER3 levels in SNU-407 cells when treated with the KRASG12D inhibitor MRTX1133. This feedback loop could limit the efficacy of the KRAS inhibitor. We wished to delineate mutant HER3’s binding partner(s) as HER3 is kinase impaired. Strikingly, we have found that EGFR immunoprecipitates with HER3 in SNU-407 cells. We are expanding our studies to CRC patient derived xenografts (PDXs) with co-occurring HER3 and KRAS mutations and have generated patient derived organoids from these PDXs. Ongoing studies are determining if there is a synergistic relationship with KRAS inhibitors and HER family inhibitors including a HER3 antibody-drug conjugate. Our findings may present a new paradigm for targeted combination therapies in colorectal cancer with the eventual goal of increased overall patient survival. Citation Format: Mary K. Kilroy, Briley Park, Rosalin Mishra, Wasim Feroz, Cecilia Wischmeier, Joan T. Garrett. Molecular insights into the oncogenic influence between mutant HER3, mutant KRAS, and their synergistic interplay in colorectal cancer pathogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7150.

Abstract 1651: Targeting intermediates of the PRMT5/BRG1 axis as a combination therapy

Abstract Over 40% of colorectal cancer (CRC) patients harbor a mutation in the KRAS gene, leading to a worse prognosis. PRMT5 and BRG1 are proteins considered potential therapeutic targets for cancer. Our lab has previously reported that both PRMT5 and BRG1 are overexpressed in KRAS mutant CRC when compared to KRAS wild-type CRC. It is therefore proposed that the PRMT5-BRG1 axis may be a strong therapeutic target for CRC. In this study, several key proteins that potentially mediate crosstalk between the PRMT5-BRG1 axis and KRAS were investigated.A literature review was first conducted to determine how the PRMT5-BRG1 axis acts in cancers. Additionally, pathways that may be involved in mediating the potential crosstalk between BRG1 and KRAS were discussed. Initial findings indicated that the PRMT5-BRG1 axis facilitates cancer oncogenesis. At the same time, the axis suppresses Myc/Max/Mad expression, leading to a dual role of the PRMT5-BRG1 axis depending on the tumor status. BRG1 was also found to work alongside mutant KRAS to affect tumor levels, with the effect differing by tumor type. The STRING database to determine the connection between the PRMT5-BRG1 axis and KRAS. It was determined that PRMT5, BRG1, and KRAS all interact with PBRM1, SMARCB1, ARID1A, and ARID2, with a combined interaction score >0.5. The UCSC Xena software was then used to analyze the mRNA data of CRC patients from The Cancer Genome Atlas (TCGA) database. Xena was utilized to determine which proteins are over expressed in CRC patient tumor samples compared to non-cancerous colon and rectum patient samples. Levels of PBRM1 and ARID1A were observed to significantly decrease in CRC patients as compared to non-cancerous samples by approximately 15% (adjp < 0.0001 and 0.05, respectively). However, SMARCB1 expression increased by 12% (adjp < 0.05). The Gene Expression Profiling Interactive Analysis (GEPIA) software was then used to analyze the correlation between the intermediary genes and PRMT5, BRG1, and KRAS in CRC patient tumor samples. PBRM1, SMARCB1, ARID1A, and ARID2 all demonstrated positive correlation with PRMT5, SMARCA4, and KRAS (R greater than 0.75 for nearly all correlations and p =0) in CRC patient tumor samples. Our study thus showcases the possible disrepair of the PRMT5/BRG1 axis in relation to KRAS. Key downstream proteins are decreased in CRC and may lower the potential crosstalk between PRMT5, BRG1, and KRAS. These findings are significant, and these key intermediate proteins may be strong therapeutic targets via inducing expression. Further research is currently in progress to outline the molecular processes behind the therapeutic role of revitalizing the SMARCA4/BRG1 axis when the downstream proteins are induced. Citation Format: Aaron Shaykevich, Isaac Silverman, Alexander Siegman, Radhashree Maitra. Targeting intermediates of the PRMT5/BRG1 axis as a combination therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1651.

Abstract 1250: Activating PIK3CA mutations and hedgehog signaling may confer resistance to KRAS inhibition in colorectal cancer

Abstract Background: Treatment with KRASG12C inhibitors results in an objective response in only small fraction of patients with KRASG12C mutant colorectal cancer (CRC) (7.1% and 22% objective response rates (ORR) in two prospective trials), in contrast to lung cancer where the ORR exceeds 35%. We hypothesize that co-mutation of other oncogenes and/or transcriptomic factors may contribute to the resistance of KRASG12C CRC to KRAS inhibitors. Methods: Mutation profiles of CRC patients were obtained from the AACR Project-GENIE v14 CRC cohort (N = 9441). The impact of KRAS knockout in 59 CRC cell lines was queried from the DepMap database. KRASG12C mutant CRC cell lines SW837 and SW1463 were treated with Sotorasib (KRASG12C inhibitor), Vismodegib and Taladegib (Hedgehog inhibitors), and cell viability was measured up to 96 hours after treatment. Results: In the AACR Project-GENIE CRC (N = 9441) cohort, KRASG12C tumors (2.6%, 245/9441) were significantly co-mutated with PIK3CAmut (19.2%, 47/245; Odds ratio = 1.7 (95% CI: 1.2 - 2.4), Chi-Square test, p-value = 0.002). Dependence on KRAS in CRISPR knockout viability assays was higher in KRASmut vs. wildtype CRC cell lines (median CERES score -1.3 vs -0.5, p-value < 0.001). Interestingly, KRASmut cell lines with PIK3CA co-mutation (n=10) were more resistant to KRAS knockout than PIK3CAwt cells (n=22) (median -1.0 vs -1.4, p-value = 0.03). The SW837 and SW1463 cell lines initially displayed high sensitivity to Sotorasib (IC50: 0.92 µM and 0.90 µM). However, overexpression of PIK3CAE545K mutant induced resistance to the same treatment (IC50: 5.18 µM and 6.45 µM). Furthermore, gene set enrichment analysis (GSEA) showed that Hedgehog signaling was significantly enriched in KRAS knockout resistant KRASmut CRC cell lines. SW837 cell line treated with Sotorasib (S) and a fixed dosage of 25 µM of Vismodegib (V) or Taladegib (T) showed higher sensitivities in combination treatment assays (IC50 decreased: ~11 folds in S+V vs S; and ~15 folds in S+T vs S) as compared to Sotorasib (S) treatment alone. Similar results were seen for the SW1463 cell line (IC50 decreased: ~18 folds in S+V vs S; and ~15 folds in S+T vs S). Conclusion: Resistance in CRC to KRASG12C inhibitors may be attributed to activated PIK3CA mutations and the Hedgehog signaling pathway. The future study will focus on detailed investigations involving comprehensive transcriptome and exome profiles in tumors and PDX models treated with anti-KRAS drugs in monotherapy and combination therapy. Citation Format: Saikat Chowdhury, Jibran Ahmed, Valsala Haridas, David S. Hong, Scott Kopetz, John Paul Shen. Activating PIK3CA mutations and hedgehog signaling may confer resistance to KRAS inhibition in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1250.

Abstract 6139: Genetic modifiers of KRAS-mutant colorectal cancer

Abstract Somatic driver mutations in KRAS are found in ~40% of colorectal cancers (CRCs) and are associated with worse outcomes. In the US, individuals of African ancestry with CRC are more likely to have tumors with KRAS mutations than individuals of European ancestry, even after considering differences in socioeconomic status and other risk factors. Germline variants can influence somatic mutation events and may provide a selective advantage such that a mutated cell is more likely to progress to a cancer. Germline variants have been found to associate with somatic mutations in a variety of tumors. Based on ancestry differences in KRAS tumor mutation frequency, we hypothesized that germline variants altering molecular pathways that support KRAS tumorigenesis will associate with KRAS-mutant status. To test this, we performed a two-step association study using KRAS mutation status as our phenotype in individuals with microsatellite stable CRC. First, we conducted a discovery analysis using genome-wide germline genotypes and somatic mutation data from 6,386 non-Hispanic White CRC patients from the Cancer Genome Atlas and the GECCO consortium, considering sex and tumor location as covariates. To select variants for additional study, we used in-silico tools, such as expression quantitative trait loci (eQTL), to predict how associated variants may alter gene expression and chromatin. After reviewing relevant genomic features, excluding SNVs with minor allele frequency <10% and pruning SNVs in linkage disequilibrium (r2>0.75), we identified candidate loci for a multi-ancestry independent validation analysis. In the discovery analysis, no variants met genome-wide significance thresholds (p-value <5x10-8), though 3 SNVs associated with KRAS mutation status with p-values <1x10-6 and 50 with p-values <1x10-5. Of these 50 SNVs, 21 met criteria for validation. We chose 80 additional SNVs (p-value <1x10-4) with predicted functional effect, for a total of 101 SNVs for analyses. In our preliminary validation analysis of 1,487 individuals grouped by self-reported race, no variants had a significant association in all populations. The rs726800 variant showed nominal association with KRAS mutation status (p-value=0.028) in self-reported non-Hispanic White individuals. This variant is within potential cis-regulatory distance of HS3ST3A1 and COX10-DT, both of which have been reported as cancer biomarkers. Nominal associations were identified in self-reported Black (n=7 SNVs) and Hispanic or Latino (n=3 SNVs) individuals, though both groups had limited sample sizes. Additional validation samples are being analyzed, as well as analysis with adjustment for genetic ancestry. Future functional studies of top candidate variants will add mechanistic insight. In summary, we identified germline SNVs that associate with KRAS somatic mutations in CRC and may inform the cellular context that supports development of colorectal tumors with KRAS mutations. Citation Format: Nijole P. Tjader, Johnny Ramroop, Tanish Gandhi, Peter T. Campbell, Andrew T. Chan, Steven Gallinger, Graham G. Giles, Marc J. Gunter, Tabitha A. Harrison, Michael Hoffmeister, Polly A. Newcomb, Shuji Ogino, Amanda I. Phipps, Conghui Qu, Robert E. Schoen, Andrew Pellatt, Michael O. Woods, Bethany Van Guelpen, Patrick Stevens, Heather Hampel, Ulrike Peters, Joseph P. McElroy, Amanda E. Toland. Genetic modifiers of KRAS-mutant colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6139.

Impact of carbamazepine on SMARCA4 (BRG1) expression in colorectal cancer: modulation by KRAS mutation status

SummarySMARCA4 is a gene traditionally considered a tumor suppressor. Recent research has however found that SMARCA4 likely promotes cancer growth and is a good target for cancer treatment. The drug carbamazepine, an autophagy inducer, was used on colorectal cancer cell lines, HCT1116 and Hke3 (KRAS mutant and wildtype). Our study finds that Carbamazepine affects SMARCA4 levels and that this effect is different depending on the KRAS mutation status. This study analyzes the effect of carbamazepine on early-stage autophagy via ULK1 as well as simulates the docking of carbamazepine on KRAS, depending on the mutation status. Our study highlights the therapeutic uses of carbamazepine on cancer, and we propose that carbamazepine in conjunction with other chemotherapies may prove useful in targeting KRAS-mutated colorectal cancer.

The effect of novel nitrogen-based chalcone analogs on colorectal cancer cells: Insight into the molecular pathways

In colorectal cancer (CRC), aberrations in KRAS are associated with aggressive tumorigenesis and an overall low survival rate because of chemoresistance and adverse effects. Ergo, complementary, and integrative medicines are being considered for CRC treatment. Among which is the use of natural chalcones that are known to exhibit anti-tumor activities in KRAS mutant CRC subtypes treatment regimens. Consequently, we examine the effect of two novel compounds (DK13 and DK14) having chalcones with nitrogen mustard moiety on CRC cell lines (HCT-116 and LoVo) with KRAS mutation. These compounds were synthesized in our lab and previously reported to exhibit potent activity against breast cancer cells. Our data revealed that DK13 and DK14 treatment suppress cell growth, disturb the progression of cell cycle, and trigger apoptosis in CRC cell lines. Besides, treatment with both compounds impedes cell invasion and colony formation in both cell lines as compared to 5-FU; this is accompanied by up and down regulations of E-cadherin and Vimentin, respectively. At the molecular level, both compounds deregulate the expression and phosphorylation of β-catenin, Akt and mTOR, which are the main likely molecular mechanisms underlying these biological occurrences. Our findings present DK13 and DK14 as novel chemotherapies against CRC, through β-catenin/Akt/mTOR signaling pathways.

Andrographolide sensitizes KRAS-mutant colorectal cancer cells to cetuximab by inhibiting the EGFR/AKT and PDGFRβ/AKT signaling pathways

BackgroundCetuximab, an inhibitor targeting EGFR, is widely applied in clinical management of colorectal cancer (CRC). Nevertheless, drug resistance induced by KRAS-mutations limits cetuximab's anti-cancer effectiveness. Furthermore, the persistent activation of EGFR-independent AKT is another significant factor in cetuximab resistance. Nevertheless, the mechanism that EGFR-independent AKT drives cetuximab resistance remains unclear. Thus, highlighting the need to optimize therapies to overcome cetuximab resistance and also to explore the underlying mechanism. PurposeThis work aimed to investigate whether and how andrographolide enhance the therapeutic efficacy of cetuximab in KRAS-mutant CRC cells by modulating AKT. MethodsThe viabilities of CRC cell lines were analyzed by CCK-8. The intracellular proteins phosphorylation levels were investigated by Human Phospho-kinase Antibody Array analysis. Knockdown and transfection of PDGFRβ were used to evaluate the role of andrographolide on PDGFRβ. The western blotting was used to investigate Wnt/β-catenin pathways, PI3K/AKT, and EMT in KRAS-mutant CRC cells. The animal models including subcutaneous tumor and lung metastasis were performed to assess tumor response to therapy in vivo. ResultsAndrographolide was demonstrated to decrease the expression of PI3K and AKT through targeting PDGFRβ and EGFR, and it enhanced cetuximab effect on KRAS-mutant CRC cells by this mechanism. Meanwhile, andrographolide helped cetuximab to inhibit Wnt/β-catenin, CRC cell migration and reduced Vimentin expression, while increasing that of E-cadherin. Lastly, co-treatment with cetuximab and andrographolide reduced the growth of KRAS-mutant tumors and pulmonary metastases in vivo. ConclusionsOur findings suggest that andrographolide can overcome the KRAS-mutant CRC cells' resistance to cetuximab through inhibiting the EGFR/PI3K/AKT and PDGFRβ /AKT signaling pathways. This research provided a possible theory that andrographolide sensitizes KRAS-mutant tumor to EGFR TKI.

Effectiveness of 225Ac-Labeled Anti-EGFR Radioimmunoconjugate in EGFR-Positive Kirsten Rat Sarcoma Viral Oncogene and BRAF Mutant Colorectal Cancer Models.

Eighty percent of colorectal cancers (CRCs) overexpress epidermal growth factor receptor (EGFR). Kirsten rat sarcoma viral oncogene (KRAS) mutations are present in 40% of CRCs and drive de novo resistance to anti-EGFR drugs. BRAF oncogene is mutated in 7%-10% of CRCs, with even worse prognosis. We have evaluated the effectiveness of [225Ac]Ac-macropa-nimotuzumab in KRAS mutant and in KRAS wild-type and BRAFV600E mutant EGFR-positive CRC cells invitro and invivo. Anti-CD20 [225Ac]Ac-macropa-rituximab was developed and used as a nonspecific radioimmunoconjugate. Methods: Anti-EGFR antibody nimotuzumab was radiolabeled with 225Ac via an 18-membered macrocyclic chelator p-SCN-macropa. The immunoconjugate was characterized using flow cytometry, radioligand binding assay, and high-performance liquid chromatography, and internalization was studied using live-cell imaging. In vitro cytotoxicity was evaluated in 2-dimensional monolayer EGFR-positive KRAS mutant DLD-1, SW620, and SNU-C2B; in KRAS wild-type and BRAFV600E mutant HT-29 CRC cell lines; and in 3-dimensional spheroids. Dosimetry was studied in healthy mice. The invivo efficacy of [225Ac]Ac-macropa-nimotuzumab was evaluated in mice bearing DLD-1, SW620, and HT-29 xenografts after treatment with 3 doses of 13 kBq/dose administered 10 d apart. Results: In all cell lines, invitro studies showed enhanced cytotoxicity of [225Ac]Ac-macropa-nimotuzumab compared with nimotuzumab and controls. The inhibitory concentration of 50% in the DLD-1 cell line was 1.8 nM for [225Ac]Ac-macropa-nimotuzumab versus 84.1 nM for nimotuzumab. Similarly, the inhibitory concentration of 50% was up to 79-fold lower for [225Ac]Ac-macropa-nimotuzumab than for nimotuzumab in KRAS mutant SNU-C2B and SW620 and in KRAS wild-type and BRAFV600E mutant HT-29 CRC cell lines. A similar trend was observed for 3-dimensional spheroids. Internalization peaked 24-48 h after incubation and depended on EGFR expression. In the [225Ac]Ac-macropa-nimotuzumab group, 3 of 7 mice bearing DLD-1 tumors had complete remission. Median survival was 40 and 34 d for mice treated with phosphate-buffered saline and [225Ac]Ac-macropa-rituximab (control), respectively, whereas it was not reached for the [225Ac]Ac-macropa-nimotuzumab group (>90 d). Similarly, median survival of mice bearing HT-29 xenografts was 16 and 12.5 d for those treated with [225Ac]Ac-macropa-rituximab and phosphate-buffered saline, respectively, and was not reached for those treated with [225Ac]Ac-macropa-nimotuzumab (>90 d). One of 7 mice bearing HT-29 xenografts and treated using [225Ac]Ac-macropa-nimotuzumab had complete remission. Compared with untreated mice, [225Ac]Ac-macropa-nimotuzumab more than doubled (16 vs. 41 d) the median survival of mice bearing SW620 xenografts. Conclusion: [225Ac]Ac-macropa-nimotuzumab is effective against KRAS mutant and BRAFV600E mutant CRC models.

KRAS-mutant colorectal cancer cell lines cause a prothrombotic state through the upregulation of thrombin: experimental study

Background: The KRAS genotype status is strongly associated with a prothrombotic state in colorectal cancer, and hypercoagulability and cancer-related thrombosis are among the significant events leading to poor prognosis. However, this correlation has not been confirmed at the cellular level. This study aimed to assess the maximum platelet aggregation rate and thrombin expression induced by colorectal cancer cells under different KRAS genotypes. Materials and methods: Platelet aggregation rate assay and western blotting analysis were used to detect platelet aggregation and thrombin expression induced by four colorectal cancer cells with different KRAS genotypes, including RKO, HCT116, SW480, and SW620. FVIIa/tissue factor and thrombin inhibitors were added to explore changes in platelet aggregation rates induced by colorectal cancer cells and the association between KRAS genotype status and hypercoagulable state. Results: KRAS-mutant cells were more likely to increase maximal platelet aggregation, with RKO, HCT116, SW480, and SW620 inducing 34.7%, 55.4%, 44.4%, and 63.8% of platelet aggregation, respectively. The maximum platelet aggregation rate was higher in the metastatic rectal cancer tumour strain SW620 than in the primary rectal cancer strain SW480. RKO cells had lower thrombin expression than the other three cells. Furthermore, the addition of thrombin inhibitors caused a more significant decrease in the platelet aggregation rate in KRAS-mutant cell lines compared to KRAS wild-type cell lines. Conclusion: Compared to KRAS wild-type colorectal cancer cells, KRAS-mutant colorectal cancer cell lines were more likely to be hypercoagulable through the upregulation of thrombin expression, which was mainly achieved through the TF-thrombin pathway.

Association of candidate alterations with primary resistance to KRAS G12D targeting in colorectal cancer.

170 Background: KRAS-mutant colorectal cancer (CRC) has a worse prognosis and greater resistance to therapy, attracting tremendous efforts to develop both allele-specific and pan-KRAS targeting agents including KRAS G12C and G12D inhibitors. CRC has demonstrated both primary and acquired resistance to KRAS G12C inhibitors, which can be better evaluated by circulating tumor DNA (ctDNA)-based next generation sequencing (NGS) methods without tissue sampling bias. Here, we utilized clinical ctDNA data to delineate the landscape of candidate alterations associated with primary resistance to KRAS G12D targeting in CRC. Methods: Samples from advanced CRC patients with Guardant360 data in 2021 were categorized into a KRAS G12D group and comparator groups of KRAS G12C and KRAS not detected (ND) according to KRAS mutation status. Demographics, MSI-H status, and blood tumor mutational burden (bTMB) were summarized and compared between groups using t-test for continuous variables and Fisher’s exact test for categorical variables. Co-occurrence patterns of alterations between KRAS and other genes were assessed. Primary resistance mutations were inferred by acquired resistance findings to KRAS G12C inhibitors reported by Awad et al. N Engl J Med. 2021 and Tanaka et al. Cancer Discov. 2021. Results: Among approximately 2500 samples, 16.8% had KRAS G12D, the most common KRAS mutation in CRC. The mean allele frequency of KRAS G12D (11.4%) is comparable to that of KRAS G12C (10.9%). Mean age (61.6 years), MSI-H frequency (3.8%), and mean bTMB (14.2 Mut/Mb) of KRAS G12D group is comparable to those of KRAS ND group. This contrasts with KRAS G12C with significantly lower mean age (60.2 years, p=0.01), lower MSI-H frequency (0.56%, p=0.03), and higher mean bTMB (16.3 Mut/Mb, p=0.02) compared to KRAS ND. Both KRAS G12D and G12C significantly co-occur with APC, PIK3CA, and SMAD4 alterations. FBXW7, AR, and KEAP1 alterations were unique co-occurrences to KRAS G12D, while KIT was unique to KRAS G12C. Candidate alterations associated with primary resistance in KRAS G12D CRC included simultaneously present mutations of KRAS Q61H (14.1%), G12V (6.4%), G12C (5.9%), G13D (3.6%), BRAF V600E (2.7%) and others, amplification of MET (2%), MYC (1.6%), and KRAS (1.4%), and FGFR3-TACC3 translocation (Table). Conclusions: KRAS G12D is associated with unique co-occurring molecular alterations compared to KRAS G12C in CRC. ctDNA-based NGS platforms can survey candidate alterations associated with primary resistance to KRAS G12D targeting in CRC. Further validation in preclinical models is needed. [Table: see text]

Onvansertib in Combination with FOLFIRI and Bevacizumab in Second-Line Treatment of KRAS-Mutant Metastatic Colorectal Cancer: A Phase Ib Clinical Study.

Onvansertib is a highly specific inhibitor of polo-like kinase 1 (PLK1), with demonstrated safety in solid tumors. We evaluated, preclinically and clinically, the potential of onvansertib in combination with chemotherapy as a therapeutic option for KRAS-mutant colorectal cancer. Preclinical activity of onvansertib was assessed (i) in vitro in KRAS wild-type and -mutant isogenic colorectal cancer cells and (ii) in vivo, in combination with irinotecan, in a KRAS-mutant xenograft model. Clinically, a phase Ib trial was conducted to investigate onvansertib at doses 12, 15, and 18 mg/m2 (days 1-5 and 14-19 of a 28-day cycle) in combination with FOLFIRI/bevacizumab (days 1 and 15) in patients with KRAS-mutant metastatic colorectal cancer who had prior oxaliplatin exposure. Safety, efficacy, and changes in circulating tumor DNA (ctDNA) were assessed. In preclinical models, onvansertib displayed superior activity in KRAS-mutant than wild-type isogenic colorectal cancer cells and demonstrated potent antitumor activity in combination with irinotecan in vivo. Eighteen patients enrolled in the phase Ib study. Onvansertib recommended phase II dose was established at 15 mg/m2. Grade 3 and 4 adverse events (AE) represented 15% of all treatment-related AEs, with neutropenia being the most common. Partial responses were observed in 44% of patients, with a median duration of response of 9.5 months. Early ctDNA dynamics were predictive of treatment efficacy. Onvansertib combined with FOLIFRI/bevacizumab exhibited manageable safety and promising efficacy in second-line treatment of patients with KRAS-mutant metastatic colorectal cancer. Further exploration of this combination therapy is ongoing. See related commentary by Stebbing and Bullock, p. 2005.

Nuclear pore protein POM121 regulates subcellular localization and transcriptional activity of PPARγ

Manipulation of the subcellular localization of transcription factors by preventing their shuttling via the nuclear pore complex (NPC) emerges as a novel therapeutic strategy against cancer. One transmembrane component of the NPC is POM121, encoded by a tandem gene locus POM121A/C on chromosome 7. Overexpression of POM121 is associated with metabolic diseases (e.g., diabetes) and unfavorable clinical outcome in patients with colorectal cancer (CRC). Peroxisome proliferator-activated receptor-gamma (PPARγ) is a transcription factor with anti-diabetic and anti-tumoral efficacy. It is inhibited by export from the nucleus to the cytosol via the RAS-RAF-MEK1/2-ERK1/2 signaling pathway, a major oncogenic driver of CRC. We therefore hypothesized that POM121 participates in the transport of PPARγ across the NPC to regulate its transcriptional activity on genes involved in metabolic and tumor control. We found that POM121A/C mRNA was enriched and POM121 protein co-expressed with PPARγ in tissues from CRC patients conferring poor prognosis. Its interactome was predicted to include proteins responsible for tumor metabolism and immunity, and in-silico modeling provided insights into potential 3D structures of POM121. A peptide region downstream of the nuclear localization sequence (NLS) of POM121 was identified as a cytoplasmic interactor of PPARγ. POM121 positivity correlated with the cytoplasmic localization of PPARγ in patients with KRAS mutant CRC. In contrast, POM121A/C silencing by CRISPR/Cas9 sgRNA or siRNA enforced nuclear accumulation of PPARγ and activated PPARγ target genes promoting lipid metabolism and cell cycle arrest resulting in reduced proliferation of human CRC cells. Our data suggest the POM121-PPARγ axis as a potential drugable target in CRC.

The 5-/12-lipoxygenase-BLT2 cascade induces elevated expression of c-Myc, thus mediating the proliferation and migration of KRAS mutant colorectal cancer cells

ABSTRACTColorectal cancer (CRC) is the most common malignant tumor and one of the leading causes of cancer-related death worldwide. Oncogene KRAS is a commonly mutated in CRC and plays crucial roles in the colorectal tumorigenesis. Emerging evidence suggests that increased expression levels of c-Myc are critical for KRAS-mediated CRC progression. However, it is unclear exactly how c-Myc expression is regulated in CRC. In the present study, we found that blockade of 5/12-lipoxygenase (5/12-LO) or leukotriene B4 receptor (BLT2) markedly reduced c-Myc expression in KRAS-mutant LOVO cells, while the control COLO 320DM cells were not affected. When the 5/12-LO products LTB4 and 12(S)-HETE, ligands of BLT2, were added to LOVO cells, c-Myc expression levels were restored, together suggesting that ‘5/12-LO-BLT2 cascade’ regulates c-Myc expression in KRAS-mutant CRC cells. We also observed that ‘5/12-LO-BLT2’-mediated c-Myc upregulation contributes to cell proliferation by regulating the expression of cyclin D1 in LOVO cells. Moreover, ‘5/12-LO-BLT2-cMyc’ cascade regulates the expression of EMT-related proteins in KRAS-mutant CRC cells, and depletion of both c-Myc and BLT2 using siRNA significantly enhanced the level of E-cadherin and reduced the level of Vimentin in LOVO cells. Taken together, our findings suggest that the BLT2-linked cascade promotes KRAS-mutant CRC cell proliferation and migration through the elevated expression of c-Myc. Thus, our results suggest that BLT2 appears to be an effective therapeutic target for KRAS-mutant CRCs.

P53-armed oncolytic adenovirus induces autophagy and apoptosis in KRAS and BRAF-mutant colorectal cancer cells.

Colorectal cancer (CRC) cells harboring KRAS or BRAF mutations show a more-malignant phenotype than cells with wild-type KRAS and BRAF. KRAS/BRAF-wild-type CRCs are sensitive to epidermal growth factor receptor (EGFR)-targeting agents, whereas KRAS/BRAF-mutant CRCs are resistant due to constitutive activation of the EGFR-downstream KRAS/BRAF signaling pathway. Novel therapeutic strategies to treat KRAS/BRAF mutant CRC cells are thus needed. We recently demonstrated that the telomerase-specific replication-competent oncolytic adenoviruses OBP-301 and p53-armed OBP-702 exhibit therapeutic potential against KRAS-mutant human pancreatic cancer cells. In this study, we evaluated the therapeutic potential of OBP-301 and OBP-702 against human CRC cells with differing KRAS/BRAF status. Human CRC cells with wild-type KRAS/BRAF (SW48, Colo320DM, CACO-2), mutant KRAS (DLD-1, SW620, HCT116), and mutant BRAF (RKO, HT29, COLO205) were used in this study. The antitumor effect of OBP-301 and OBP-702 against CRC cells was analyzed using the XTT assay. Virus-mediated modulation of apoptosis, autophagy, and the EGFR-MEK-ERK and AKT-mTOR signaling pathways was analyzed by Western blotting. Wild-type and KRAS-mutant CRC cells were sensitive to OBP-301 and OBP-702, whereas BRAF-mutant CRC cells were sensitive to OBP-702 but resistant to OBP-301. Western blot analysis demonstrated that OBP-301 induced autophagy and that OBP-702 induced autophagy and apoptosis in human CRC cells. In BRAF-mutant CRC cells, OBP-301 and OBP-702 suppressed the expression of EGFR, MEK, ERK, and AKT proteins, whereas mTOR expression was suppressed only by OBP-702. Our results suggest that p53-armed oncolytic virotherapy is a viable therapeutic option for treating KRAS/BRAF-mutant CRC cells via induction of autophagy and apoptosis.

SLC25A21 downregulation promotes KRAS-mutant colorectal cancer progression by increasing glutamine anaplerosis.

Emerging evidence shows that KRAS-mutant colorectal cancer (CRC) depends on glutamine (Gln) for survival and progression, indicating that targeting Gln metabolism may be a promising therapeutic strategy for KRAS-mutant CRC. However, the precise mechanism by which Gln metabolism reprogramming promotes and coordinates KRAS-mutant CRC progression remains to be fully investigated. Here, we discovered that solute carrier 25 member 21 (SLC25A21) expression was downregulated in KRAS-mutant CRC, and that SLC25A21 downregulation was correlated with poor survival of KRAS-mutant CRC patients. SLC25A21 depletion selectively accelerated the growth, invasion, migration, and metastasis of KRAS-mutant CRC cells in vitro and in vivo, and inhibited Gln-derived α-ketoglutarate (α-KG) efflux from mitochondria, thereby potentiating Gln replenishment, accompanied by increased GTP availability for persistent KRAS activation in KRAS-mutant CRC. The restoration of SLC25A21 expression impaired the KRAS-mutation-mediated resistance to cetuximab in KRAS-mutant CRC. Moreover, the arrested α-KG efflux that occurred in response to SLC25A21 depletion inhibited the activity of α-KG-dependent DNA demethylases, resulting in a further decrease in SLC25A21 expression. Our studies demonstrate that SLC25A21 plays a significant role as a tumor suppressor in KRAS-mutant CRC by antagonizing Gln-dependent anaplerosis to limit GTP availability for KRAS activation, which suggests potential alternative therapeutic strategies for KRAS-mutant CRC.

Early changes in circulating tumor DNA (ctDNA) predict treatment response in metastatic KRAS-mutated colorectal cancer (mCRC) patients

The detection of RAS mutations and co-mutations in liquid biopsy offers a novel paradigm for the dynamic management of metastatic colorectal cancer (mCRC) patients.Expanding the results of the prospective OMITERC (OMIcs application from solid to liquid biopsy for a personalized ThERapy of Cancer) project, we collected blood samples at specific time points from patients who received a first-line chemotherapy (CT) for KRAS-mutated mCRC. CTC quantification was performed by CellSearch® system. Libraries from cfDNA were prepared using the Oncomine™ Colon cfDNA Assay to detect tumour-derived DNA in cfDNA. The analysis involved >240 hotspots in 14 genes.Twenty patients with KRAS-mutated mCRC treated at the Medical Oncology Unit of Careggi University Hospital were prospectively enrolled. Nine patients had available data for longitudinal monitoring of cfDNA. After 6 weeks of first-line CT an increase of KRAS-mutated clone was reported in the only patient who did not obtain disease control, while all patients with decrease of KRAS clones obtained disease control. Overall, in patients with a short (<9 months) progression-free survival (PFS) we registered, at 6 weeks, an increase in cfDNA levels and in KRAS mutations or other co-mutations, i.e. PIK3CA, FBXW7, GNAS, and TP53. In selected cases, co-mutations were able to better anticipate radiological progressive disease (PD) than the increase of KRAS-mutated clones.In conclusion, our study confirms plasma ctDNA as a crucial tool for anticipating PD at an early time point and highlights the value of a comprehensive assessment of clonal dynamics to improve the management of patients with mCRC.

Noncoding RNA Profile in Reovirus Treated KRAS-Mutated Colorectal Cancer Patients.

To investigate the alterations in the expression of noncoding, micro, and small RNA expression during treatment with oncolytic reovirus in KRAS-mutated colorectal cancer. Oncolytic reovirus treatment was administered in phase 1 clinical trial (NCT01274624) for 5 days every 28 days, and blood samples were collected before the administration of the reovirus and 48 h, 8 days, and 15 days after its administration on day 1. Data from the blood samples were sorted using Transcriptome Analysis Software (TAC) 4.0, where a two-tailed t-test and a fold change filter were used to ascertain which sample signals had a statistically significant relative fold change of greater than 2 at multiple timepoints before or after oncolytic reovirus administration. The long noncoding RNA's RP11-332M2.1 (-6.1 x), LINC01506 (-16.18 x), and LINC00534 (-1.94 x) were downregulated at 48 h after reovirus administration [p < 0.05]. ncRNA's EPB41L4A-AS1 (-6.34 x, 48 h; 11.99 x, day 8), JAK2 (2.2 x, 48 h; -2.23 x, day 8), ANXA4 (20.47 x, day 8; -7.54 x, day 15), and PCDH9 (-2.09, day 8; 1.82 x, day 15) were affected by the reovirus treatment and reflected the progress of the treatment [p < 0.05]. The small RNA SNORA26 (-1.59 x, day 8) was downregulated 48 h after the reovirus administration [p < 0.05]. The microRNA MIR-4461 (6.18 x, day 8; -3.76 x, day 15) was also affected by the reovirus administration [p < 0.05]. The administration of oncolytic reovirus to treat KRAS-mutated colorectal cancer is reflected in a noncoding RNA profile, and expression levels of the ncRNAs in that profile may thus be able to be used as a potential predictive marker for reovirus-treated colorectal cancer.

35P Enhancing efficacy of the MEK inhibitor trametinib in KRAS-mutated colorectal cancer cells

35P Enhancing efficacy of the MEK inhibitor trametinib in KRAS-mutated colorectal cancer cells