Aurora kinase A drives non-canonical YAP1/TAZ crosstalk to sustain primary resistance to anti-EGFR therapies in colorectal cancer

Background: Although anti-epidermal growth factor receptor (EGFR) therapy has established efficacy in RAS/BRAF wild type (WT) metastatic colorectal cancer (mCRC), a significant proportion (30-50%) of WT patients exhibit primary resistance to this treatment. Existing biomarker discovery has predominantly focused on tumor-specific DNA mutations, which suffer from variable mutation frequencies among patients. In contrast, DNA methylation represents a common and early event in carcinogenesis. For this reason, methylation markers hold great promise for detecting resistance mechanisms in primary tumors. Several studies have shown an association between DNA methylation patterns and resistance to anti-EGFR therapy in CRC. To validate and build upon these findings, we investigated the methylomes of primary tumors with resistant and responsive phenotypes. Material and Methods: We isolated DNA from FFPE tissue of 40 primary CRC tumors. DNA was subjected to bisulfite conversion and Infinium MethylationEPIC v2.0 BeadChip (Illumina). Subsequently, ChAMP was used to determine the methylation values (β values) and perform differential methylation analysis. The CpG sites were ranked based on the largest Δβ values and the significance of p-values across the patient groups. To ensure the reliability of our findings, we performed a false discovery rate (FDR) evaluation using the Benjamini-Hochberg method, which led to the selection of a subset of differentially methylated CpG sites (DMCs) with the highest likelihood of being genuine associations. Additionally, a gene set enrichment analysis (GSEA) was performed with methylGSA. Results: 48 DMCs were identified with adjusted p-values < 0.05. The affected genes are involved in cancer progression and invasiveness, suggesting a role in a yet-to-be discovered resistance mechanism. The GSEA revealed significant enrichment in 53 KEGG and 33 Reactome pathways, including MAPK-related and Akt signaling pathways. There were 470 significant gene ontology (GO) pathways: 347 in biological processes, 71 in cellular components and 52 in molecular functions. Conclusion and future work: We have found methylation sites associated with resistance to anti-EGFR therapy in CRC patients. In addition to identifying critical DMCs, the pathways uncovered hold potential as a rich source of predictive biomarkers. Next, we will include 24 additional patients. When increasing the sample size, we expect a higher statistical power and an enrichment of CpGs with significant p-values. Afterwards, we will independently validate the most significant CpG sites in a follow-up study using a highly sensitive multiplexed droplet digital PCR assay on additional tissue biopsies. Citation Format: Ana Regina de Abreu, Yann Heylen, Joe Ibrahim, Marc Peeters, Guy Van Camp, Ken Op de Beeck. Uncovering methylation signatures and pathways associated with resistance to anti-EGFR therapy in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3311.

EGF receptor (EGFR)-targeted monoclonal antibodies are effective in a subset of metastatic colorectal cancers. Inevitably, all patients develop resistance, which occurs through emergence of KRAS mutations in approximately 50% of the cases. We show that amplification of the MET proto-oncogene is associated with acquired resistance in tumors that do not develop KRAS mutations during anti-EGFR therapy. Amplification of the MET locus was present in circulating tumor DNA before relapse was clinically evident. Functional studies show that MET activation confers resistance to anti-EGFR therapy both in vitro and in vivo. Notably, in patient-derived colorectal cancer xenografts, MET amplification correlated with resistance to EGFR blockade, which could be overcome by MET kinase inhibitors. These results highlight the role of MET in mediating primary and secondary resistance to anti-EGFR therapies in colorectal cancer and encourage the use of MET inhibitors in patients displaying resistance as a result of MET amplification.

<div>Abstract<p>EGF receptor (EGFR)-targeted monoclonal antibodies are effective in a subset of metastatic colorectal cancers. Inevitably, all patients develop resistance, which occurs through emergence of <i>KRAS</i> mutations in approximately 50% of the cases. We show that amplification of the <i>MET</i> proto-oncogene is associated with acquired resistance in tumors that do not develop <i>KRAS</i> mutations during anti-EGFR therapy. Amplification of the <i>MET</i> locus was present in circulating tumor DNA before relapse was clinically evident. Functional studies show that MET activation confers resistance to anti-EGFR therapy both <i>in vitro</i> and <i>in vivo</i>. Notably, in patient-derived colorectal cancer xenografts, <i>MET</i> amplification correlated with resistance to EGFR blockade, which could be overcome by MET kinase inhibitors. These results highlight the role of MET in mediating primary and secondary resistance to anti-EGFR therapies in colorectal cancer and encourage the use of MET inhibitors in patients displaying resistance as a result of <i>MET</i> amplification.</p><p><b>Significance:</b> Amplification of the <i>MET</i> proto-oncogene is responsible for <i>de novo</i> and acquired resistance to anti-EGFR therapy in a subset of colorectal cancers. As multiple anti-MET therapeutic strategies are available, these findings offer immediate novel opportunities to design clinical studies. <i>Cancer Discov; 3(6); 658–73. ©2013 AACR</i>.</p><p>This article is highlighted in the In This Issue feature, p. 591</p></div>

<div>Abstract<p>EGF receptor (EGFR)-targeted monoclonal antibodies are effective in a subset of metastatic colorectal cancers. Inevitably, all patients develop resistance, which occurs through emergence of <i>KRAS</i> mutations in approximately 50% of the cases. We show that amplification of the <i>MET</i> proto-oncogene is associated with acquired resistance in tumors that do not develop <i>KRAS</i> mutations during anti-EGFR therapy. Amplification of the <i>MET</i> locus was present in circulating tumor DNA before relapse was clinically evident. Functional studies show that MET activation confers resistance to anti-EGFR therapy both <i>in vitro</i> and <i>in vivo</i>. Notably, in patient-derived colorectal cancer xenografts, <i>MET</i> amplification correlated with resistance to EGFR blockade, which could be overcome by MET kinase inhibitors. These results highlight the role of MET in mediating primary and secondary resistance to anti-EGFR therapies in colorectal cancer and encourage the use of MET inhibitors in patients displaying resistance as a result of <i>MET</i> amplification.</p><p><b>Significance:</b> Amplification of the <i>MET</i> proto-oncogene is responsible for <i>de novo</i> and acquired resistance to anti-EGFR therapy in a subset of colorectal cancers. As multiple anti-MET therapeutic strategies are available, these findings offer immediate novel opportunities to design clinical studies. <i>Cancer Discov; 3(6); 658–73. ©2013 AACR</i>.</p><p>This article is highlighted in the In This Issue feature, p. 591</p></div>

AimThis study aimed to compare anti-epidermal growth factor receptor (anti-EGFR) therapy and anti-vascular endothelial growth factor therapy as first-line and second-line therapies in patients with KRAS exon 2 codon 12/13 wild-type (KRAS-WT) metastatic colorectal cancer (mCRC).MethodsMajor databases were systematically searched. The hazard ratio (HR), odds ratio (OR), and 95% confidence intervals (95% CIs) were used to estimate the effect measures. Review Manager software version 5.3 was used for statistical analysis.ResultsSeven trials including ten articles were eligible in the meta-analysis. The patients treated with anti-EGFR as first-line therapy showed a longer overall survival (OS) for KRAS-WT and all RAS wild-type (RAS-WT) mCRC (HR =0.81, 95% CI: 0.72–0.92, P<0.01, n=5; HR =0.78, 95% CI: 0.66–0.93, P<0.01, n=3, respectively). The objective response rate (ORR) was better with the anti-EGFR therapy for KRAS-WT and all RAS-WT mCRC (OR =1.32, 95% CI: 1.11–1.56, P<0.01, n=5; OR =1.55, 95% CI: 1.21–2.00, P<0.01, n=3, respectively). There was no difference in progression-free survival (PFS) for KRAS-WT mCRC and all RAS-WT mCRC between the two groups (HR =1.00; 95% CI: 0.92–1.09, P=0.99, n=4; HR =0.92, 95% CI: 0.71–1.19, P=0.52, n=3, respectively). In addition, two trials provided data on the second-line therapy; there was no significant difference in OS and PFS for the second-line therapy, but a significant improvement in ORR was found in the anti-EGFR group (OR =1.91, 95% CI: 1.16–3.16, P=0.01, n=2). No difference in the conversion therapy (OR =1.34; 95% CI: 0.91–1.99; P=0.14, n=4) was observed between the two therapies.ConclusionOur results indicate that anti-EGFR therapy is superior to anti-vascular endothelial growth factor therapy for OS and ORR as a first-line therapy for KRAS-WT mCRC. In the second-line therapy, there was no significant difference in the survival outcomes on the basis of OS and PFS between the two groups. However, ORR improved significantly in the anti-EGFR group.

The prognosis of advanced colorectal cancer (CRC) remains dismal. Fibroblast growth factor (FGF) signals are potent mitogens, morphogens, and inducers of angiogenesis. Abnormal expression of FGF9 has been observed in several malignancies and might result in uncontrolled cell proliferation and carcinogenesis. However, limited information is available regarding the role of FGF9 in CRC. In this study, amplification of FGF9 gene was observed in 14/146 (9.6%) CRC specimens, using a TaqMan copy number assay. FGF9-overexpressed CRC cell lines were created, and FGF9-overexpression induced the resistance to anti-epidermal growth factor receptor (EGFR) therapy (cetuximab or lapatinib) via the FGF receptor (FGFR) signal, which was cancelled by BGJ398, a pan-FGFR inhibitor. In vivo, FGF9-overexpressed xenograft tumors were resistant to cetuximab monotherapy and the combination with BGJ398 overcame the resistance. Considering these results, FGF9 gene amplification may play an important role in the resistance to anti-EGFR therapy in CRC and the combination with an anti-FGFR inhibitor could overcome this resistance. Citation Format: Takuro Mizukami, Yosuke Togashi, Eri Banno, Masato Terashima, Marco A de velasco, Kazuko Sakai, Yoshihiko Fujita, Shuta Tomida, Takako Eguchi Nakajima, Narikazu Boku, Kazuto Nishio. FGF9 gene amplification can induce resistance to anti-EGFR therapy in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5456. doi:10.1158/1538-7445.AM2015-5456

Monoclonal antibodies targeting EGFR are used in the clinic to treat KRAS wild type metastatic colorectal cancer (CRC). After an initial response, secondary resistance occurs thereby limiting the clinical benefit of these drugs. Relapsed patients have no further therapeutic options, therefore, elucidating the molecular basis of resistance is a prerequisite for the development of further lines of therapy. We took advantage from a panel of CRC cell lines sensitive to EGFR inhibition by treating with cetuximab or panitumumab until resistant derivatives emerged. The resistant populations were heterogeneous mixture of cells bearing different alterations in KRAS, NRAS and BRAF genes at various frequencies. An RNA interference (siRNA) genetic screening unveiled that suppression of MEK1/2 together with silencing of EGFR was effective in impairing the growth of the resistant cells. Combinatorial treatment with pimasertib, a selective allosteric MEK inhibitor, together with cetuximab re-sensitizes anti-EGFR resistant derivatives despite the genetic alterations heterogeneity. Combinatorial treatment was effective in vitro and in vivo both in cell derived xenografts and in an acquired resistant patient derived xenograft (xenopatient). These observations provide a rational strategy to overcome the multifaceted clonal heterogeneity that emerges when tumors are treated with targeted agents. We propose that MEK inhibitors, in combination with cetuximab or panitumumab, should be tested in clinical trials in CRC patients who become refractory to anti-EGFR therapies. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C94. Citation Format: Sandra Misale, Sabrina Arena, Simona Lamba, Giulia Siravegna, Alice Lallo, Sebastijan Hobor, Mariangela Russo, Michela Buscarino, Andrea Sartore-Bianchi, Katia Bencardino, Alessio Amatu, Salvatore Siena, Federica Di Nicolantonio, Alberto Bardelli. Heterogeneous mechanisms of acquired resistance to anti-EGFR therapies in colorectal cancer are sensitive to concomitant inhibition of EGFR and MEK. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C94.

11005 Background: The anti EGFR monoclonal antibodies cetuximab and panitumumab are used to treat metastatic colorectal cancer patients but their clinical efficacy is limited by the development of acquired resistance. We recently reported that secondary KRAS mutations are responsible for acquired resistance in approximately 50% of the patients who initially respond to cetuximab or panitumumab (Misale et al., Nature 2012; Diaz et al., Nature 2012). Here we studied the molecular bases of relapse in CRC patients who do not develop KRAS mutations during the course of anti-EGFR therapy. Methods: Next generation sequencing was applied to tumor biopsies to identify genetic alterations associated with relapse to cetuximab and panitumumab in mCRC patients. Detection and quantitation of genetic alterations in circulating tumor DNA was used to monitor the occurrence of KRAS mutations and MET amplification in blood samples. Results: Molecular analyses of tumor biopsies from patients who did not develop KRAS mutations during anti-EGFR therapy revealed high level of amplification of the MET proto-oncogene in 3/5 cases. Quantitative PCR, FISH and IHC analysis confirmed high level of MET amplification in the post-therapy samples but not in the matched pre-treatment tissues. We developed a PCR based assay to detect the presence of the MET amplicon in circulating, cell-free, DNA. We found that MET amplification could be detected in the blood as early as 3 months after initiation of anti EGFR therapy. To functionally evaluate the role of MET amplification on resistance to anti EGFR antibody therapies we exploited patient-derived CRC xenografts (‘xenopatients). We found that (2/2) xenopatients established from MET amplified tumors were completely refractory to cetuximab but showed sensitivity to the Met inhibitor crizotinib. Conclusions: Amplification of the MET proto-oncogene is responsible for acquired acquired resistance to anti-EGFR antibody therapy in a subset of CRCs. The emergence of MET amplification in circulating, cell-free, DNA may be used to select patients most likely to benefit from anti MET therapies.

BackgroundKRAS mutations in codons 12 and 13 are established predictive biomarkers for anti-EGFR therapy in colorectal cancer. Previous studies suggest that KRAS codon 61 and 146 mutations may also predict resistance to anti-EGFR therapy in colorectal cancer. However, clinicopathological, molecular, and prognostic features of colorectal carcinoma with KRAS codon 61 or 146 mutation remain unclear.MethodsWe utilized a molecular pathological epidemiology database of 1267 colon and rectal cancers in the Nurse’s Health Study and the Health Professionals Follow-up Study. We examined KRAS mutations in codons 12, 13, 61 and 146 (assessed by pyrosequencing), in relation to clinicopathological features, and tumor molecular markers, including BRAF and PIK3CA mutations, CpG island methylator phenotype (CIMP), LINE-1 methylation, and microsatellite instability (MSI). Survival analyses were performed in 1067 BRAF-wild-type cancers to avoid confounding by BRAF mutation. Cox proportional hazards models were used to compute mortality hazard ratio, adjusting for potential confounders, including disease stage, PIK3CA mutation, CIMP, LINE-1 hypomethylation, and MSI.ResultsKRAS codon 61 mutations were detected in 19 cases (1.5%), and codon 146 mutations in 40 cases (3.2%). Overall KRAS mutation prevalence in colorectal cancers was 40% (=505/1267). Of interest, compared to KRAS-wild-type, overall, KRAS-mutated cancers more frequently exhibited cecal location (24% vs. 12% in KRAS-wild-type; P < 0.0001), CIMP-low (49% vs. 32% in KRAS-wild-type; P < 0.0001), and PIK3CA mutations (24% vs. 11% in KRAS-wild-type; P < 0.0001). These trends were evident irrespective of mutated codon, though statistical power was limited for codon 61 mutants. Neither KRAS codon 61 nor codon 146 mutation was significantly associated with clinical outcome or prognosis in univariate or multivariate analysis [colorectal cancer-specific mortality hazard ratio (HR) = 0.81, 95% confidence interval (CI) = 0.29-2.26 for codon 61 mutation; colorectal cancer-specific mortality HR = 0.86, 95% CI = 0.42-1.78 for codon 146 mutation].ConclusionsTumors with KRAS mutations in codons 61 and 146 account for an appreciable proportion (approximately 5%) of colorectal cancers, and their clinicopathological and molecular features appear generally similar to KRAS codon 12 or 13 mutated cancers. To further assess clinical utility of KRAS codon 61 and 146 testing, large-scale trials are warranted.

Background: Telomeres (T) consist of thousands of copies of TTAGGG tandem repeats capping the ends of the chromosome. Studies have linked short T length (TL) with premalignant and malignant stages of colorectal cancer (CRC) carcinogenesis. However, the relation of TL to response to drugs used in treatment of CRC has not been conclusively determined. In this study, we used a panel of CRC cell lines and analyzed each TL, and determined relationship to drug sensitivity. We validated our in vitro findings in a pool of samples collected from patients with metastatic CRC (mCRC) undergone anti-EGFR therapy at our institution. Methods: DNA was isolated from CRC cell lines grown in culture, and from formalin fixed paraffin embedded specimens. Cells were cultured and treated with varying concentrations of cetuximab, oxaliplatin, 5-FU, camptothecin, aspirin, sulindac, trichostatin, curcumin, and butyrate. TL was measured using a qRT-PCR method that provided the relative T copy number, compared to reference single copy number of the housekeeping gene, β-Globin (S), which resulted in a T/S ratio. One T/S ratio unit is equivalent to a mean TL of 4,270 base pairs. Results: In a panel of 22 CRC cell lines, TL was independently predicative of cetuximab sensitivity. When split at the median, thee cell lines with a shorter TL had a mean cetuximab sensitivity of 18.6% (growth inhibition at 20 ug/ml at 72 hours by MTT assay), as compared to 39.7% in those cells with longer TL; p=0.02. Response to all of the other drugs did not bear any relationship to TL. To further validate our in vitro finding, we analyzed the TL in patients with mCRC who had been treated with cetuximab or panitumumab. In this sample of 75 patients, 118 tissue samples were identified (66 primary, 52 metastases, 29 matched pairs). Forty five patients had received greater than 4 weeks of therapy and were considered for clinical correlates. Patients with K-Ras WT tumors had a superior progression free survival (PFS) and overall survival than those with K-Ras mutated tumors (p&amp;lt;0.05). Importantly, among the patients with K-Ras WT tumors, those with a longer TL had a superior outcome with median PFS of 28.1 weeks as compared to those with shorter TL, median14.7 weeks, p=0.019. Conclusion: TL is a potential biomarker predictive of sensitivity to cetuximab, in vitro, and of outcome for patients treated with cetuximab/panitumumab, as measured by PFS. These findings will be validated in a larger dataset, and the mechanistic basis for this finding is currently under investigation. Citation Format: Titto A. Augustine, Mahadi A. Baig, John M. Mariadason, Radhashree Maitra, Sanjay Goel. Telomere length: A novel biomarker for anti-EGFR therapy in colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2835. doi:10.1158/1538-7445.AM2014-2835

Colorectal cancer (CRC) is the third prevalent cancer worldwide, the morbidity and mortality of which have been increasing in recent years. As molecular targeting agents, anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (McAbs) have significantly increased the progression-free survival (PFS) and overall survival (OS) of metastatic CRC (mCRC) patients. Nevertheless, most patients are eventually resistant to anti-EGFR McAbs. With the intensive study of the mechanism of anti-EGFR drug resistance, a variety of biomarkers and pathways have been found to participate in CRC resistance to anti-EGFR therapy. More and more studies have implicated non-coding RNAs (ncRNAs) primarily including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are widely involved in tumorigenesis and tumor progression. They function as essential regulators controlling the expression and function of oncogenes. Increasing data have shown ncRNAs affect the resistance of molecular targeted drugs in CRC including anti-EGFR McAbs. In this paper, we have reviewed the advance in mechanisms of ncRNAs in regulating anti-EGFR McAbs therapy resistance in CRC. It provides insight into exploring ncRNAs as new molecular targets and prognostic markers for CRC.

BackgroundChemotherapy-induced oral mucositis impairs the quality of life. The difference in severity of oral mucositis between different anti-epidermal growth factor receptor (EGFR) antibodies combined with cytotoxic drugs in colorectal cancer is unclear. The aim of this study was to investigate the differences in oral mucositis between panitumumab (Pmab) and cetuximab (Cmab) combined with 5-fluorouracil (5-FU).MethodsWe conducted a retrospective cohort study. A total of 75 colorectal cancer outpatients treated with an anti-EGFR antibody combined with FOLFOX, FOLFIRI, or 5-FU/leucovorin as the first- to third-line treatment were included. The primary endpoint was the incidence of grade 2–3 oral mucositis. The secondary endpoint was the time to onset of oral mucositis. We also compared the incidence of toxicities of interest, skin toxicity, hypomagnesaemia and neutropenia, and time to treatment failure (TTF) between the two groups.ResultsThirty-two patients treated with Pmab and 43 patients treated with Cmab were evaluated. Patient characteristics were similar between the two groups. The incidence of grade 2–3 oral mucositis was significantly higher with Pmab than with Cmab (31.3% vs 9.3%, P < 0.05). Moreover, the incidence of grade 3 oral mucositis was significantly higher in patients treated with Pmab (18.8% vs 0%, P < 0.01). The mean (SD) cycles to onset of the worst oral mucositis was 3.0 (2.9) in the Pmab group and 2.3 (1.7) in the Cmab group (P = 0.29). Oral mucositis was characterized by glossitis and cheilitis. The incidences of other toxicities were the following (Pmab vs Cmab): grade 2–3 skin toxicity: 68.8% vs 74.4% (P = 0.61), grade 2–3 hypomagnesaemia: 9.3% vs 7.0% (P = 1.00), grade 3–4 neutropenia: 28.1% vs 37.2% (P = 0.46). The median TTF was not significantly different, i.e., 223 days vs 200 days (P = 0.39) for Pmab vs Cmab.ConclusionsPmab-based chemotherapy resulted in significantly higher grades of oral mucositis compared with Cmab-based chemotherapy. The oral condition should be monitored carefully and early supportive care should be provided for patients treated with Pmab-based chemotherapy.

Background:Telomeres are TTAGGG tandem repeats capping chromosomal ends and partially controlled by the telomerase enzyme. The EGFR pathway putatively regulates telomerase function, prompting an investigation of telomere length (TL) and its association with anti-epidermal growth factor receptor (EGFR) therapy in metastatic colorectal cancer (mCRC).Methods:Colorectal cancer cell lines were treated with multiple drugs and sensitivity determined. Clinical information was gathered from 75 patients who had received anti-EGFR drugs. Telomere length was measured using a validated qRT–PCR technique.Results:In CRC cell lines, TL independently predicted cetuximab sensitivity. Cells with shorter TL had growth inhibition of 18.6±3.41% as compared with 41.39±8.58% in longer TL (P=0.02). These in vitro findings were validated clinically, in a robust multivariate model. Among patients with KRas WT tumours, those with longer TL had a superior median progression-free survival (PFS) of 24.9 weeks than those with shorter TL; median 11.1 weeks, HR 0.31; P=0.048.Conclusion:Telomere length could be a potential unique biomarker predictive of clinical benefit (PFS) of mCRC patients treated with anti-EGFR therapy. This is the novel demonstration of a complex hitherto undescribed interaction, placing anti-EGFR therapy, EGFR pathway, and the telomerase complex within a clinical context.

PurposeActivating mutation of the KRAS oncogene is an established negative predictor for anti-epidermal growth factor receptor (anti-EGFR) therapies in metastatic colorectal cancer (CRC). However, KRAS mutation as a prognostic factor of survival outcome remains controversial in CRC, independent of anti-EGFR therapies.Materials and MethodsWe conducted a retrospective analysis of 103 CRC patients who were available for evaluation of KRAS mutation status. None of the patients analyzed had received anti-EGFR therapies. The role of KRAS mutation status was evaluated as a predictive factor for oxaliplatin or irinotecan and as a prognostic factor in CRC patients who did not receive anti-EGFR therapies.ResultsMutations in KRAS were observed in 48.5% of patients. The response for oxaliplatin- (p=0.664) and irinotecan-based (p=0.255) cytotoxic chemotherapy did not differ according to the KRAS mutation status. In addition, no significant difference in progression free survival (PFS; oxaliplatin, p=0.583 and irinotecan, p=0.426) and overall survival (OS; p=0.258) was observed between the wild and mutant type of the KRAS gene. In univariate and multivariate analyses, KRAS mutations did not have a major prognostic value regarding PFS (oxaliplatin: hazard ratio, 0.892; 95% confidence interval [CI], 0.590 to 1.347; p=0.586 and irinotecan: hazard ratio, 0.831; 95% CI, 0.524 to 1.319; p=0.433) or OS (hazard ratio, 0.754; 95% CI, 0.460 to 1.236; p=0.263). In addition, anti-vascular endothelial growth factor therapies did not affect PFS to oxaliplatin or irinotecan and OS.ConclusionKRAS mutation is not a prognostic marker for PFS to oxaliplatin or irinotecan and OS in CRC patients who did not receive anti-EGFR therapies.

RAS short variant (SV) mutations in colorectal cancer (CRC) are associated with lack of benefit from epidermal growth factor receptor (EGFR) monoclonal antibody (EGFRmAb). However, the clinical implications for RAS amplification (RASa) as a biomarker for anti-EGFR therapy in CRC remain ill defined. Genomic analysis was performed using the Foundation Medicine (FM) comprehensive genomic profiling database of 37,233 CRC cases. Clinical outcomes were assessed using two independent cohorts: the City of Hope (COH) cohort of 338 patients with metastatic CRC (mCRC) and the Flatiron Health-FM real-world clinicogenomic database (CGDB) of 3,904 patients with mCRC. RASa was detected in 1.6% (614/37,233) of primarily mCRC. RASa 6-9 (n = 241, 39%), 10-19 (n = 165, 27%), and ≥ 20 (n = 209, 34%) copy number subsets had co-RAS SV/BRAF V600E in 63%/3%, 31%/0.6%, and 4.8%/0% of cases, respectively. In the COH cohort, six patients with RASa (13-54 copies) received EGFRmAb, four of six had progressive disease, two had stable disease, and median time to treatment discontinuation (TTD) was 2.5 months. Of the CGDB EGFRmAb-treated patients, those with RASa (n = 9) had median TTD of 4.7 months and overall survival (OS) of 11.4 months, those with RAS SV (n = 101) had median TTD and OS of 5.3 and 9.4 months, and those with RAS/BRAF wild-type (n = 608) had median TTD and OS of 7.6 and 13.7 months. Patients with RASa without RAS mutations (1.1% of mCRC) may have poor outcomes on EGFRmAb, although numbers herein were small, and interpretation is confounded by combination chemotherapy. Larger independent studies are warranted to determine if RASa, including degree of amplification, may act similarly to RAS mutation as a resistance mechanism to EGFRmAb therapies. Genomic data suggest that RAS amplification occurs as the sole RAS/RAF alteration in >1% of colorectal cancer cases and that degree of amplification inversely correlates with co-occurring MAPK pathway alterations. Preliminary clinical evidence suggests that RAS amplification may function similarly to RAS mutation as a negative predictor of benefit from anti-epidermal growth factor receptor therapies in colorectal cancer. More clinical data are needed, and comprehensive genomic profiling, including detection of RAS amplification, should be used in trial design to inform therapy selection.