Clinical Outcome In mCRC Patients Research Articles

Abstract A37: Early change in circulating tumor DNA as a potential predictor of response to chemotherapy in patients with metastatic colorectal cancer

Abstract The impact of the change in ctDNA levels after chemotherapy on the clinical outcomes of patients with metastatic colorectal cancer (mCRC) remains unclear. The present study evaluated the clinical implications of the early change in ctDNA levels as a predictor of objective response and the clinical outcome in mCRC patients who received chemotherapy. We investigated the effects of after/before ratio of ctDNA levels 2 and 8 weeks after initiation of second-line chemotherapy on objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). ctDNA was detected using amplicon-based deep sequencing with a molecular barcode that includes >240 hotspot mutations in 14 colon cancer-related genes. Patients with lower ctDNA level (≤ 50%) 8 weeks after initiation of chemotherapy compared to baseline showed significantly longer PFS and OS than the patients with higher (> 50%) ctDNA level in multivariate analysis. In patients achieving partial response or stable disease, the after/before ratio of ctDNA level 8 weeks after initiation of chemotherapy was significantly lower than those in patients with progressive disease. The present study suggests that an early change in the ctDNA level might serve as a biomarker to predict the chemotherapeutic efficacy and clinical outcomes in patients with mCRC. Citation Format: Hitoshi Zembutsu, Hiroki Osumi, Eiji Shinozaki, Kensei Yamaguchi. Early change in circulating tumor DNA as a potential predictor of response to chemotherapy in patients with metastatic colorectal cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A37.

Circulating IL-8 levels as candidate marker of antiangiogenic therapy for metastatic colorectal cancer.

172 Background: Liver metastasis (LM) confers poor prognosis in metastatic colorectal cancer (mCRC). It has not been well understood whether tumor microenvironment (TM) varies throughout cancer treatment in the presence of LM. We therefore investigated the difference of TM between first-line (FL) and savage-line (SL) anti-angiogenic therapies and tested whether specific angiogenic cytokines could predict clinical outcome in mCRC patients. Methods: A combined cohort consisting of two cohorts (N = 125) was included in this study: 71 patients received first-line treatment with bevacizumab (FL cohort: median age, 60; median follow-up, 28.9 mos) and 54 patients received salvage-line regorafenib (SL cohort: median age, 65; median follow-up, 17.2 mos). Blood samples were obtained from all patients at baseline (BL) and during the treatment, and serum levels of nine angiogenic cytokines were measured using ELISA. Progression-free survival and overall survival (OS) were analyzed using Kaplan-Meier curves, log-rank test, and Cox proportional hazard regression. Results: In univariate analysis for the combined cohort, right-sided CRC, primary unresected, KRAS wild-type, LM, metastatic site ≥2 and SL were associated with shorter OS, and LM and SL remained in multivariable analysis. Ang-2 and IL-8 levels at BL were significantly associated with LM and their cut-off values were 2190.3 pg/ml (COAng2) and 15.1 pg/ml (COIL8), respectively, and no significant interaction was shown between cytokines and cohorts. Patients with Ang-2 levels ≥COAng2 had shorter OS than those with Ang-2 levels < COAng2 (HR2.57, 95%CI: 1.47–4.51, P = 0.001), while IL-8 levels ≥COIL8 was associated with shorter OS than < COIL8 (HR4.31, 95%CI: 2.11–8.79, P < 0.001). IL-8 levels ≥COIL8 remained as significant in multivariable analysis (HR 3.24, 95%CI: 1.47–7.16, P = 0.004). In change analysis, there was no significant correlation of variation of IL-8 and Ang-2 levels with clinical outcome after the first treatment cycle in both cohorts. Conclusions: Circulating IL-8 and Ang-2 levels reflect the TM in the presence of LM, of which IL-8 may serve as solid prognostic marker of anti-angiogenic therapy regardless of the timing of treatment for mCRC.

Early change in circulating tumor DNA as a potential predictor of response to chemotherapy in patients with metastatic colorectal cancer

The impact of ctDNA changes after chemotherapy on the clinical outcomes of patients with metastatic colorectal cancer (mCRC) remains unclear. The present study evaluated the clinical implications of the early change in ctDNA levels as a predictor of objective response and clinical outcome in mCRC patients who received chemotherapy. We investigated the effects of after/before ratio of ctDNA levels 2 and 8 weeks after initiation of second-line chemotherapy, on objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). ctDNA was detected using amplicon-based deep sequencing with a molecular barcode encompassing >240 hotspot mutations in 14 colon cancer-related genes. In multivariate analysis, as compared to baseline, patients with lower ctDNA level (≤50%) 8 weeks after initiation of chemotherapy showed significantly longer PFS and OS than the patients with higher (>50%) ctDNA level. In patients achieving a partial response or stable disease, the after/before ratio of ctDNA level 8 weeks after initiation of chemotherapy was significantly lower than those in patients with progressive disease. The present study suggests that an early change in the ctDNA level might serve as a biomarker to predict the chemotherapeutic efficacy and clinical outcomes in patients with mCRC.

Patients with hMLH1 or/and hMSH2-deficient Metastatic Colorectal Cancer Are Associated with Reduced Levels of Vascular Endothelial Growth Factor-1 Expression and Higher Response Rate to Irinotecan-based Regimen.

The benefit of IFL (irinotecan, fluorouracil and leucovorin) regimen for metastatic colorectal cancer patients (mCRCs) with high levels of microsatellite instability (MSI-H) or loss of mismatch repair (dMMR) protein expression, is uncertain. This study investigated the association of tumour MMR-status and VEGF-1 expression with response to first-line IFL regimen in mCRCs. This prospective study analyzed patients diagnosed with mCRC between August 1st, 1998, and August 30th, 2003, at the Turku University Hospital, Finland. All patients received postoperative IFL regimen. Tumour expression of the MMR proteins, hMLH1 and hMSH2, and VEGF-1 expression were assessed by immunohistochemistry (IHC). Tumours with dMMR were those demonstrating loss of MMR protein expression, and tumours with high VEGF-1 expression were those showing moderate or strong cytoplasmic staining. The primary endpoint was the association between tumour hMLH1 or/and hMSH2-deficient and VEGF-1 expression; the relation between tumour MMR-status and IFL response rate was the secondary endpoint. Of the 67 mCRCs patients, 29 (43%) were hMLH1 or/and hMSH2-deficient and 15 (22%) were pMMR mCRCs. At diagnosis, patients with hMLH1 or/and hMSH2-deficient tumours expressed lower levels of VEGF-1 compared to pMMR tumour patients (p=0.01). More than half (n=17, 59%) of those with dMMR were chemosensitive to first-line IFL regimen, while just one-fifth (n=3, 20%) of those with pMMR were chemosensitive to the IFL regimen (p=0.045). Association between MMR-status and VEGF-1 expression predicts clinical outcome in mCRC patients.

Genetic variants of DNA repair-related genes predict efficacy of TAS-102 in patients with refractory metastatic colorectal cancer

Tri-phosphorylated trifluridine (FTD) incorporation into DNA is TAS-102's main anti-tumor action. We tested whether genetic polymorphisms in homologous recombination (HR) and cell cycle checkpoint pathway for DNA repair is associated with outcomes in refractory metastatic colorectal cancer (mCRC) patients treated with TAS-102. We analyzed genomic DNA extracted from 233 samples of three cohorts: an evaluation cohort of 52 patients receiving TAS-102, a validation cohort of 129 patients receiving TAS-102 and a control cohort of 52 patients receiving regorafenib. Single nucleotide polymorphisms of genes involved in HR (ATM, BRCA1, BRCA2, XRCC3, FANCD2, H2AX, RAD51) and cell cycle checkpoint (ATR, CHEK1, CHEK2, CDKN1A, TP53, CHE1, PIN1, PCNA) were analyzed by PCR-based direct sequencing. In univariate analysis for the evaluation cohort, patients with any G allele in ATM rs609429 had longer overall survival (OS) than those with the C/C variant (8.7 vs. 4.4 months, HR 0.37, 95% CI: 0.14-0.99, P = 0.022). Patients carrying any A allele in XRCC3 rs861539 had significantly longer progression-free survival (PFS) (3.8 vs. 2.3 months, HR 0.44, 95% CI: 0.21-0.92, P = 0.024) and OS (15.6 vs. 6.3 months, HR 0.25, 95% CI: 0.08-0.79, P = 0.012) than those with the G/G variant. In multivariable analysis, ATM rs609429 remained significant for OS (P = 0.020). In the validation cohort, patients having ATM rs609429 with any G allele showed longer OS and PFS; the G/A variant in XRCC3 rs861539 showed longer OS, though without statistical significance. Genetic variants in the HR pathway may predict clinical outcome in mCRC patients receiving TAS-102.

Topoisomerase 1 Promoter Variants and Benefit from Irinotecan in Metastatic Colorectal Cancer Patients

Objective:Topoisomerase 1 (topo-1) is an important target for the treatment of metastatic colorectal cancer (CRC). The aim of the present study was to evaluate the correlation between topo-1 single-nucleotide polymorphisms (SNPs) and clinical outcome in metastatic CRC (mCRC) patients. Methods: With the use of specific software (PROMO 3.0), we performed an in silico analysis of topo-1 promoter SNPs; the rs6072249 and rs34282819 SNPs were included in the study. DNA was extracted from 105 mCRC patients treated with FOLFIRI ± bevacizumab in the first line. SNP genotyping was performed by real-time PCR. Genotypes were correlated with clinical parameters (objective response rate, progression-free survival, and overall survival). Results: No single genotype was significantly associated with clinical variables. The G allelic variant of rs6072249 topo-1 SNP is responsible for GC factor and X-box-binding protein transcription factor binding. The same allelic variant showed a nonsignificant trend toward a shorter progression-free survival (GG, 7.5 months; other genotypes, 9.3 months; HR 1.823, 95% CI 0.8904-3.734; p = 0.1). Conclusion: Further analyses are needed to confirm that the topo-1 SNP rs6072249 and transcription factor interaction could be a part of tools to predict clinical outcome in mCRC patients treated with irinotecan-based regimens.

Genetic variants in immune response genes to predict clinical outcome in mCRC patients treated with FOLFIRI/cetuximab (FIRE-3) or with first line cetuximab-based chemotherapy (JACCRO CC-05/06 AR).

3595Background: Cetuximab can exert its anti-tumor mechanisms by stimulating of the immune system via ADCC (antibody-dependent cell-mediated cytotoxicity). Immune response through T-cell activation...

Genetic variants of R-spondin genes to predict clinical outcome in mCRC patients (pts) treated with first line FOLFIRI and bevacizumab (FOLFIRI/BEV) in FIRE-3 cohort.

3586Background: The secreted Wnt agonists of the R-spondin (RSPO) family, RSPO1-4, play important roles as Wnt coactivators by interacting with LGR receptors, leading to stabilization of Frizzles a...

Genetic variant of TWEAK to predict clinical outcome in mCRC patients (pts) treated with first line FOLFIRI and Bevacizumab (FOLFIRI/BEV) in FIRE-3 and TRIBE cohorts.

3554 Background: Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), acting via the Fn14 cell surface receptor, is a multifunctional pro-inflammatory/pro-angiogenic cytokine that particip...

Anti-epidermal growth factor receptor monoclonal antibodies in metastatic colorectal cancer: a meta-analysis.

To investigate the correlation between Kirsten rat sarcoma viral oncogene homolog (KRAS) status and the therapeutic effects of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) in metastatic colorectal cancer (mCRC). Randomized controlled trials (RCTs) were identified and the association between KRAS mutation and clinical outcome in mCRC patients treated with anti-EGFR MoAbs was investigated. Ten RCTs were included in this meta-analysis. Progression-free survival and overall survival were used to assess the strength of the relationship between KRAS mutation and clinical outcome. In first-line treatment, survival benefit was confined to patients with wild-type KRAS. Chemotherapy regimens and angiogenesis inhibitor treatment influenced the results of the analysis. Wild-type KRAS mCRC patients did not seem to benefit from oxaliplatin-based chemotherapy (PFS: HR = 0.88, 95%CI: 0.70-1.10; OS: HR = 0.93, 95%CI: 0.82-1.04). Clinical benefit in mCRC patients was limited to therapeutic regimens which included anti-EGFR MoAbs and fluorouracil-based therapy (PFS: HR = 0.77, 95%CI: 0.69-0.86; OS: HR = 0.85, 95%CI: 0.75-0.95). When anti-EGFR MoAbs were used as second- or further-line treatment, clinical benefit was still confined to patients with wild-type KRAS. KRAS status is a potential predictive marker of clinical benefit due to anti-EGFR MoAb therapy in mCRC patients.

Serum protein profiling reveals baseline and pharmacodynamic biomarker signatures associated with clinical outcome in mCRC patients treated with chemotherapy ± cediranib.

Background:This study evaluated soluble serum proteins as biomarkers to subset patients with metastatic colorectal cancer (mCRC) treated with chemotherapy±cediranib, a vascular endothelial growth factor (VEGF) signalling inhibitor (VEGFi). Exploring biomarkers at pre- and on-treatment may identify patient subgroups showing clinical benefit on cediranib combination.Methods:Two hundred and seven serum proteins were analysed in 588 mCRC patients at pre- and on-treatment with chemotherapy (FOLFOX/CAPOX)±cediranib 20 mg. Patients were enrolled in the phase III trial HORIZON II. We correlated baseline biomarker signatures and pharmacodynamic (PD) biomarkers with PFS and OS.Results:We identified a baseline signature (BS) of 47 biomarkers that included VEGFA, VEGFD, VEGFR2, VEGFR3 and TIE-2, which defined two distinct subgroups of patients. Patients treated with chemotherapy plus cediranib who had ‘high' BS had shorter PFS (HR=1.82, P=0.003) than patients with ‘low' BS. This BS did not correlate with PFS of the patients treated with chemotherapy plus placebo. In addition, we identified a profile of 16 PD proteins on treatment associated with PFS (HR=0.58, P<0.001) and OS (HR=0.52, P<0.001) in patients treated with chemotherapy plus cediranib. This PD profile did not correlate with PFS and OS in patients treated with chemotherapy plus placebo.Conclusions:Serum proteins may represent relevant biomarkers to predict the outcome of patients treated with VEGFi-based therapies. We report a BS and PD biomarkers that may identify mCRC patients showing increased benefit of combining cediranib with chemotherapy. These exploratory findings need to be validated in future prospective studies.

High-throughput exome array for identification of novel polymorphisms associated with clinical outcome in mCRC patients treated with first-line FOLFOXIRI/BEV versus FOLFIRI/BEV (TRIBE trial; NCT00719797).

3632 Background: TRIBE is a phase III randomized trial comparing FOLFOXIRI/ Bev vs FOLFIRI/Bev as first-line treatment for metastatic colorectal cancer. In this post genomic area, whole exome seque...

MRNA expression levels of candidate genes and clinical outcome in mCRC patients treated with FOLFOXIRI plus bevacizumab (bev) or FOLFIRI plus bev in the TRIBE study.

3640 Background: Phase III TRIBE trial demonstrated that first-line FOLFOXIRI plus bev improved PFS and RECIST response and, at adjusted analyses, OS as compared to FOLFIRI plus bev. Previous data ...

C.35 G &gt; A KRAS-mutant genotype and clinical outcome of patients with metastatic colorectal cancer.

512 Background: KRAS genotype does not significantly affect prognosis of MCRC patients treated with bevacizumab-containing chemotherapy. Codon 12 mutations increase aggressiveness by differently modifying mutated KRAS and downstream signalling, thus conferring worse clinical behavior. Prognostic relevance of the prevalent c.35 G &gt; A KRAS mutation in MCRC patients fit and unfit for first-line bevacizumab added to triplet chemotherapy (FIr-B/FOx) was evaluated. Methods: KRAS codon 12/13 mutations were screened. Efficacy was evaluated and compared by log-rank. Results: Fifty-nine fit patients were treated with firstline FIr-B/FOx: wild-type, 31 (53%); mutant, 28 (47%). KRAS mutations: c.35 G &gt; A, 15 (25.4%); c.35 G &gt; T, 7 (11.8%); c.38 G &gt; A, 3 (5%); other, 3 (5%). Wild-type compared to mutant status did not significantly affect PFS (14 and 11 months) and OS (38 and 20 months). c.35 G &gt; A mutant showed: no significantly different PFS compared to wild-type; significantly worse OS (14 months) compared to wild-type and to other mutant (39 months). After progression, wild-type compared with mutant did not show significantly different PFS (10 months equivalently) nor OS (17 and 12 months); c.35 G &gt; A compared to wild-type and/or other mutant showed significantly worse PFS and OS. Among 39 unfit patients, treated with conventional regimens, wild-type compared to mutant significantly affected PFS (8 and 6 months), and not OS (13 and 8 months); c.35 G &gt; A mutation significantly affected worse PFS and OS compared to wild-type and/or other mutant. Conclusions: KRAS genotype does not significantly affect clinical outcome of MCRC patients treated with first line FIr-B/FOx, while mutant status may significantly affect worse PFS in patients unfit for intensive treatments. c.35 G &gt; A mutant status, compared to wild type and other mutant, may significantly affect worse clinical outcome in MCRC patients treated with first line intensive FIr-B/FOx and after progression, as well as in patients unfit for FIr-B/FOx, due to increased biological aggressiveness. It did not affect worse PFS only in patients treated with FIr-B/FOx, probably due to effectiveness of triplet chemotherapy plus VEGF inhibitor.

Association of a polymorphism in amphiregulin with worse prognosis in metastatic colorectal cancer patients treated with cetuximab.

e14543 Background: Accumulating data suggests that Amphiregulin (AREG) and Epiregulin (EREG), ligands of the EGFR pathway, are potential prognostic and predictive markers in metastatic colorectal cancer (mCRC). Elevated AREG and EREG gene expression levels are predictive of improved response rates in mCRC patients treated with cetuximab and longer overall survival (OS) in patients with mCRC who did not receive cetuximab. Since polymorphisms in AREG and EREG may affect their expression or function, we tested whether AREG and EREG polymorphisms were associated with clinical outcome in mCRC patients treated with cetuximab. Methods: Seventy-three patients (n=73) with histopathologically-confirmed mCRC with Kras/Braf wild type were enrolled in Italy. These patients were treated with cetuximab monotherapy or irinotecan plus cetuximab as second or third line treatment. Genomic DNA was extracted from blood and 4 SNPs in AREG and 5 SNPs in EREG were analyzed by direct DNA-sequencing. Results: The median follow-up period was 13.3 months in this cohort. The median progression-free survival (PFS) and OS were 5.2 and 12.9 months respectively. The results indicate that the intronic AREG polymorphism rs28364983 A/C was associated with shorter PFS and OS. Patients with homozygous C/C (n=2) showed a median PFS of 2.3 months vs. 5.3 months for patients harboring at least one-A allele (n=71) (HR: 4.26 [95%CI: 0.98-18.5], p=0.05). Patients with homozygous C/C showed a median OS of 3.0 months vs. 13.1 months for patients harboring at least one-A allele (HR: 3.98 [95%CI: 0.93-16.9], p=0.062). An independent cohort of thirty-three patients was used to validate these initial findings and showed that patients with homozygous C/C (n=3) had a median PFS of 2.3 months vs. 3.8 months for patients harboring at least one-A allele (n=103) (HR: 3.79 [95%CI: 1.16-12.3], p=0.027) and a median OS of 3.0 months vs. 8.4 months (HR: 3.01 [95%CI: 0.93-9.71], p=0.065), respectively. Conclusions: AREG rs28364983 predicted worse outcome in mCRC patients treated with cetuximab; however, further analyses are necessary to understand the mechanism and further validate the prognostic and/or predictive role of this polymorphism.

Use of genetic variants in immune response genes to predict clinical outcome in mCRC patients treated with cetuximab-based therapy.

3567 Background: Cetuximab is a monoclonal antibody targeting the EGF receptor. One of its anti-tumor mechanisms is the stimulation of the immune system via ADCC (Antibody-Dependent-Cell mediated Cytotoxicity). Immune response through T-cell activation may also play a role in antitumor efficacy of chemotherapy. CTLA4, PDL1, IDO1 and CD24 are inhibitory co-receptors or ligands that may downregulate the immune system through suppression of T-cell response. We tested whether Germline polymorphisms in these genes are involved in the cetuximab dependent immune response pathway and thus predict outcome in mCRC patients treated with cetuximab. Methods: DNA was isolated from blood of 108 patients with mCRC treated with either irinotecan+cetuximab (n=73) or single agent cetuximab (n=35). Twelve prospectively functionally relevant SNPs; IDO1(rs9657182, rs3739319, rs1010866), PD1(rs2227981, rs7421861), PDL1(rs2297137, rs2297136, rs10122089, G&gt;C), CTLA4(rs231777, rs231775), and CD24(rs8734) were analyzed by PCR-based direct sequencing and evaluated for association with tumor response, overall survival (OS), and progression free survival (PFS). Results: Results are attached. There were 65 men and 43 women with a median PFS of 3.7 (95%CI: 2.8, 4.6) months and a median OS of 10.5 (95%CI:7.7, 13.3) months. Median follow up was 16.3 (range:1.2, 42.4) months. Conclusions: Our results show that immune response related SNPs may predict efficacy of cetuximab treatment in patients with mCRC. To the best of our knowledge this is the first data linking PDL1(rs2297137) to cetuximab efficacy in mCRC patients. [Table: see text]

Abstract 2393: Fc gamma receptor IIIa polymorphisms correlated with antibody-dependent cell-mediated cytotoxicity (ADCC): anti-EGFR antibodies induced and clinical outcome in metastatic colorectal cancer patients.

Abstract Anti-EGFR monoclonal antibodies have shown efficacy in the treatment of metastatic colorectal cancer (mCRC). One of the mechanism is the antibody-dependent cell-mediated cytotoxicity (ADCC) in which Fc region of the antibody binds to the Fc gamma receptors (FcγR) expressed by immune cells. The present study investigated the association between single nucleotide polymorphisms of FcγRIIa and FcγRIIIa, in vitro ADCC and clinical outcome in mCRC patients treated with anti-EGFR antibodies. Fifty-five consecutive patients with mCRC were analyzed and the genotypes were distributed as follow: 38%HH, 47%HR and 15%RR for FcγRIIa; 26%VV, 44%VF and 30%FF for FcγRIIIa. The genotype frequencies in both were in Hardy-Weinberg Equilibrium. Heterozygosis for FcγRIIa-H131R and FcγRIIIa-V158F polymorphisms were the most common genotype detected in mCRC and in healthy subjects (n=148) . The genotype frequencies of the H131R and V158F did not significantly differ between the two groups (p= 0.626, p=0.613 respectively). ADCC-cetuximab mediated was evaluate in HT29 human colon cancer cell line through two in vitro assays (SRB assayand CytoTox96) demonstrated to be technically comparable. Interleukin-2 (IL-2) activated PBMCs (LAK) cells of 55 study cases were used to evaluate in vitro ADCC-cetuximab mediated against HT-29, human colon cancer cells. Patients carrying the Fc gamma IIIA genotypes V/V or V/F induced an higher ADCC- cetuximab mediated compared to F/F carrying patients (average value ADCC with cetuximab-ADCC without cetuximab in patients carrying VV genotype = 39%, average value ADCC with cetuximab-ADCC without cetuximab in patients carrying V/F = 21% and average value ADCC with cetuximab-ADCC without cetuximab in patients carrying F/F genotype 6% respectively;p&amp;lt;0.001). To investigate the role of FcγRIIIa higher expression in ADCC, FcγRIIIa mRNA expression was determined by quantitative real-time PCR in 34 mCRC patients distributed for genotype as follows 12VV, 14VF and 8FF. Although the FcγRIIIa transcript level was higher in patients with FcRIIIa-158 V/V or V/F compared to F/F, analysis of variance showed no statistically significant differences (p=0.240). The study is currently recruiting consecutive mCRC patients evaluating FcγR polymorphisms, the effective in vitro cetuximab-ADCC activity and biological tumor features to be evaluated with a prognostic/ predictive intent. Citation Format: Anna Maria Trotta, Alessandro Ottaiano, Serena Zannotta, Maria Napolitano, Guglielmo Nasti, Rosario Vincenzo Iaffaioli, Stefania Scala. Fc gamma receptor IIIa polymorphisms correlated with antibody-dependent cell-mediated cytotoxicity (ADCC): anti-EGFR antibodies induced and clinical outcome in metastatic colorectal cancer patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2393. doi:10.1158/1538-7445.AM2013-2393

543P - P16(INK4A) Gene Hypermethylation and Kras Mutation are Independent Predictors of FolFiri and Cetuximab Chemotherapy in Patients with Metastatic Colorectal Cancer (MCRC)

ABSTRACT Background P16 (INK4a) inhibits cyclin dependent kinases (CDKs) and plays various roles in cancer and senescence. P16 aberrancy is frequently detected in various cancers and may contribute to multidrug resistance. Hypermethylation of CpG island of p16 occurs in a significant proportion in colorectal cancer (CRC) and also is one of the CpG island methylator phenotype (CIMP) markers. Patients and method We analyzed tumor samples from 49 patients with metastatic colorectal cancer (mCRC) who were treated with 5-fluorouracil, leucovorin, irinotecan (FOLFIRI) and cetuximab (1st line 22 pts, 2nd line 27 pts). Pyrosequencing was used to identify KRAS mutation and hypermethylation of 6 CpG island loci (p16, p14, MINT1, MINT2, MINT31, hMLH1) in DNA extracted from formalin-fixed paraffin-embedded specimens. To analyze the relation between methylation status of CIMP markers including p16 and clinical outcome, logistic regression and Cox regression were performed. Result Hypermethylation of p16 gene was detected in 14 of 49 patients (28.6%) and was significantly associated with KRAS mutation (Fisher's exact, P = 0.01) and CIMP+ (Fisher's exact, P = 0.002). Patients with p16 unmethylated tumors had significant longer time to progression (TTP, median 9.0 vs 3.5 months; log-rank, P = 0.001) and overall survival (OS, median 44.9 vs 16.4 months; log-rank, P = 0.008) than those with p16 methylated tumors. KRAS mutation was also associated with shortened TTP (median 8.9 vs 4.4 months; HR = 3.1, P = 0.008) and OS (median 44.9 vs 16.1 months; HR = 5.2, P Conclusion Promoter CpG island hypermethylation of p16 was predictive of clinical outcome in mCRC patients treated with cetuximab and FOLFIRI, irrespective of KRAS mutation. Disclosure All authors have declared no conflicts of interest.

Beyond KRAS mutation status: influence of KRAScopy number status and microRNAs on clinical outcome to cetuximab in metastatic colorectal cancer patients

BackgroundKRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor (EGFR) antibodies in metastatic colorectal cancer (mCRC). Novel predictive markers are required to further improve the selection of patients for this treatment. We assessed the influence of modification of KRAS by gene copy number aberration (CNA) and microRNAs (miRNAs) in correlation to clinical outcome in mCRC patients treated with cetuximab in combination with chemotherapy and bevacizumab.MethodsFormalin-fixed paraffin-embedded primary tumour tissue was used from 34 mCRC patients in a phase III trial, who were selected based upon their good (n = 17) or poor (n = 17) progression-free survival (PFS) upon treatment with cetuximab in combination with capecitabine, oxaliplatin, and bevacizumab. Gene copy number at the KRAS locus was assessed using high resolution genome-wide array CGH and the expression levels of 17 miRNAs targeting KRAS were determined by real-time PCR.ResultsCopy number loss of the KRAS locus was observed in the tumour of 5 patients who were all good responders including patients with a KRAS mutation. Copy number gains in two wild-type KRAS tumours were associated with a poor PFS. In KRAS mutated tumours increased miR-200b and decreased miR-143 expression were associated with a good PFS. In wild-type KRAS patients, miRNA expression did not correlate with PFS in a multivariate model.ConclusionsOur results indicate that the assessment of KRAS CNA and miRNAs targeting KRAS might further optimize the selection of mCRC eligible for anti-EGFR therapy.

Loss of PTEN expression as a predictor of resistance to anti-EGFR monoclonal therapy in metastatic colorectal cancer: evidence from retrospective studies

To investigate the predictive value of loss of PTEN expression in patients with metastatic colorectal cancer (mCRC) treated with anti-EGFR monoclonal therapy. Studies were systematically identified to investigate the relationship between PTEN expression and clinical outcome in mCRC patients treated with anti-EGFR MoAbs. Clinical outcomes included objective response rate (ORR), progression-free survival (PFS) and overall survival (OS). The pooled relative risk (RR) or hazard ratio (HR) was estimated using a fixed-effects model or a random-effects model according to the heterogeneity between the studies. A total of 852 patients were included in the final meta-analysis. The rate of loss of PTEN expression was 28.4% (242/852). The overall pooled RR for ORR was 0.413 (95% confidence intervals (CI), 0.177-0.965) when patients with loss of PTEN expression were compared with those with normal PTEN expression. Anti-EGFR monoclonal therapy resulted in improved PFS (HR, 0.466; 95% CI, 0.292-0.640) and OS (HR, 0.689 [95% CI, 0.482-0.896]) in patients unselected by KRAS mutation with normal PTEN expression over loss of PTEN expression. A better prognosis, as reflected by PFS (HR, 0.344; 95% CI, 0.154-0.533) and OS (HR, 0.544; 95% CI, 0.285-0.803), was observed in wild-type KRAS patients with normal PTEN expression versus loss of expression. Loss of expression of PTEN is a potential biomarker for resistance to anti-EGFR monoclonal therapy, particularly in mCRC patients with KRAS wild type.