KRAS4A and KRAS4B in liquid biopsy of metastatic lung adenocarcinoma patients treated with Pembrolizumab or chemotherapy plus Pembrolizumab

KRAS is involved in the stability and expression of PD-L1. We investigated the expression of circulating mRNA (cmRNA) of KRAS4A and KRAS4B and the possible impact on progression-free survival (PFS) of patients with metastatic lung adenocarcinoma treated with immunotherapy. Patients without driver mutations undergoing Pembrolizumab (P) or P plus chemotherapy (PC) were prospectively accrued for liquid biopsy analysis of KRAS4A, KRAS4B, and PD-L1 cmRNA. Both KRAS isoforms were also studied for association with PD-L1 cmRNA. Of 56 patients, 28 received P and 28 PC. Patients with high levels of both KRAS isoforms showed significantly better PFS. The median PFS for KRAS4A was 29 months (95% CI 22-29 months) and KRAS4B 24 months (95% CI 13-29 months), respectively. The median PFS of patients with low levels of both isoforms was 12 months (95% CI 6-15 months for KRAS4A and 95% CI 5-20 months for KRAS4B). High KRAS4A retained a significant positive association with PFS in the multivariate model. An exploratory analysis in treatment subgroups found a positive association between high KRAS4A and KRAS4B with PFS in patients treated with P. PD-L1 cmRNA was significantly higher in patients with high KRAS isoforms levels and this effect was pronounced for high KRAS4A carriers. KRAS4A deserves further investigation as a potential marker for defining patients who may benefit the most from immune checkpoint inhibitors therapy and improving personalized cancer immunotherapeutic strategies.

Metabolic Switch and Cytotoxic Effect of Metformin on Burkitt Lymphoma

Altered cellular energetic metabolism has recently emerged as important feature of neoplastic cells. Indeed, interfering with cancer cell metabolism might represent a suitable therapeutic strategy. In this study, we aimed to assess glucose metabolism activation in human lymphomas and evaluate how metformin can exert its action on lymphoma cells. We studied a large series of human lymphomas (N = 252) and an in vitro model of Burkitt lymphoma (BL) cells. We combined molecular biology techniques, including global gene expression profiling (GEP) analysis, quantitative PCR (qPCR) and Western blotting, and biochemical assays, aimed to assess pentose phosphate pathway, tricarboxylic acid (TCA) cycle, and aerobic glycolysis rates. We found that glucose metabolism is overall enhanced in most lymphoma subtypes, based on gene expression profiling (GEP), with general shift to aerobic glycolysis. By contrast, normal B cells only showed an overall increase in glucose usage during germinal center transition. Interestingly, not only highly proliferating aggressive lymphomas but also indolent ones, like marginal zone lymphomas, showed the phenomenon. Consistently, genes involved in glycolysis were confirmed to be overexpressed in BL cells by qPCR. Biochemical assays showed that while aerobic glycolysis is increased, TCA cycle is reduced. Finally, we showed that metformin can induce cell death in BL cells by stressing cellular metabolism through the induction of GLUT1, PKM2, and LDHA. In conclusion, we unveiled glucose metabolism abnormalities in human lymphomas and characterized the mechanism of action of metformin in Burkitt lymphoma model.

Clinical Relevance of ABCB1, ABCG2, and ABCC2 Gene Polymorphisms in Chronic Myeloid Leukemia Patients Treated With Nilotinib

Tyrosine kinase inhibitors (TKIs) have radically changed the outcome of chronic myeloid leukemia (CML) patients in the last 20 years. Moreover, the advent of second generation TKIs, namely nilotinib and dasatinib, have largely increased the number of CML patients achieving deep and sustained molecular responses. However, the possible mechanisms capable of influencing the maintenance of the long-term molecular response are not yet fully known and understood. In this light, polymorphisms in MDR-ABC transporters may influence the efficacy and safety of TKIs. In this study, we examined seven single nucleotide polymorphisms (SNPs) in four ABC transporter genes: ABCC1 rs212090 (5463T>A), ABCC2 rs3740066 (3972C>T), ABCC2 rs4148386 G>A, ABCC2 rs1885301 (1549G>A), ABCG2 rs2231137 (34G>A), ABCG2 rs2231142 G>C, ABCB1 rs1045642 (3435C>T), to determine their effect on the achievement and/or loss of molecular response in 90 CML patients treated with nilotinib. We found that ABCC2 rs3740066 CC and CT as well as the ABCB1 rs1045642 TT genotypes correlated with a higher probability to achieve MR3 in a shorter time (p=0.02, p=0.004, and p=0.01), whereas ABCG2 rs2231137 GG was associated with lower probability of MR3 achievement (p=0.005). Moreover, ABCC2 rs3740066 CC genotype, the ABCB1 rs1045642 CC and TT genotypes were positively correlated with MR4 achievement (p=0.02, p=0.007, and p=0.003). We then generated a predictive model incorporating the information of four genotypes, to evaluate the combined effect of the SNPs. The combination of SNPs present in the model affected the probability and the time to molecular response. This model had a high prognostic significance for both MR3 and MR4 (p=0.005 and p=0.008, respectively). Finally, we found ABCG2 rs2231142 GG genotype to be associated with a decrease risk of MR3 loss. In conclusion, MDR-transporters SNPs may significantly affect the achievement and loss of molecular response in CML patients treated with nilotinib.

MetaTropismDB: a database of organ-specific metastasis induced by human cancer cell lines in mouse models

The organotropism is the propensity of metastatic cancer cells to colonize preferably certain distant organs, resulting in a non-random distribution of metastases. In order to shed light on this behaviour, several studies were performed by the injection of human cancer cell lines into immunocompromised mouse models. However, the information about these experiments is spread in the literature. For each xenograft experiment reported in the literature, we annotated both the experimental conditions and outcomes, including details on inoculated human cell lines, mouse models, injection methods, sites of metastasis, organs not colonized, rate of metastasis, latency time, overall survival and the involved genes. We created MetaTropismDB, a freely available database collecting hand-curated data useful to highlight the mechanisms of organ-specific metastasis. Currently, it stores the results of 513 experiments in which injections of 219 human cell lines have been carried out in mouse models. Notably, 296 genes involved in organotropic metastases have been collected. This specialized database allows the researchers to compare the current results about organotropism and plan future experiments in order to identify which tumour molecular signatures establish if and where the metastasis will develop. Database URL:  http://www.introni.it/Metastasis/metastasis.html.

Glycolytic competence in gastric adenocarcinomas negatively impacts survival outcomes of patients treated with salvage paclitaxel-ramucirumab

INTRODUCTION

For energy production, cancer cells maintain a high rate of glycolysis instead of oxidative phosphorylation converting glucose into lactic acid. This metabolic shift is useful to survive in unfavorable microenvironments. We investigated whether a positive glycolytic profile (PGP) in gastric adenocarcinomas may be associated with unfavorable outcomes under an anticancer systemic therapy, including the anti-angiogenic ramucirumab.

MATERIALS AND METHODS

Normal mucosa (NM) and primary tumor (PT) of 40 metastatic gastric adenocarcinomas patients who received second-line paclitaxel-ramucirumab (PR) were analyzed for mRNA expression of the following genes: HK-1, HK-2, PKM-2, LDH-A, and GLUT-1. Patients were categorized with PGP when at least a doubling of mRNA expression (PT vs. NM) in all glycolytic core enzymes (HK-1 or HK-2, PKM-2, LDH-A) was observed. PGP was also related to TP53 mutational status.

RESULTS

Mean LDH-A, HK-2, PKM-2 mRNA expression levels were significantly higher in PT compared with NM. 18 patients were classified as PGP, which was associated with significantly worse progression-free and overall survival times. No significant association was observed between PGP and clinical-pathologic features, including TP53 positive mutational status, in 28 samples.

CONCLUSIONS

Glycolytic proficiency may negatively affect survival outcomes of metastatic gastric cancer patients treated with PR systemic therapy. TP53 mutational status alone does not seem to explain such a metabolic shift.

TP53 mutation analysis in gastric cancer and clinical outcomes of patients with metastatic disease treated with anti-angiogenic or standard chemotherapy regimens

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Background: Current data support the angiogenic potential of cancer cells with mutant p53 and VEGF-A up-regulation in solid tumors. These findings have renewed interest in the p53 role as a predictive/prognostic factor in cancer therapy. We investigated TP53 mutations in gastric adenocarcinoma (GA) samples of metastatic patients (pts) who underwent anti-angiogenic Paclitaxel-Ramucirumab (PR) therapy. The analysis was also performed in a control group of pts who received first-line chemotherapy (CT) with platinum derivates and fluoropyrimidines. Methods: TP53 mutations were identified by next-generation sequencing in 110 GA primary tumors of two retrospective metastatic series including 48 pts who were treated with second-line PR and 62 pts who received first-line CT with Cisplatin or Oxaliplatin plus 5-Fluorouracil or Capecitabine. Detected TP53 mutations were classified for TP53 mutant-specific residual transcriptional activity scores ( TP53 RTAS) (Fischer NW et al JCI Insight 2018). TP53 RTAS results were used for stratifying pts in survival analyses. Primary end-point was overall survival (OS). Results: In the PR group, TP53 mutations were detected in 29 out of 48 tumor samples (60.4%) with 10 having TP53 RTAS 0%-to-<1%. In the CT group, TP53 mutations were found in 40 out of 62 tumor samples (64.5%) with 11 having TP53 RTAS 0%-to-<1%. In the PR group, the 10 cases with a TP53 mutation causing no residual or minimal activity ( TP53 RTAS 0%-to-<1%) showed better OS in comparison with pts in the remaining groups (wild-type and TP53 RTAS > 1%). This effect was retained in the multivariate model analysis (Hazard Ratio = 0.29, 95% confidence interval 0.17-0.85, p = 0.02). An opposite effect was seen in the CT group with the worst OS in carriers of TP53 RTAS 0%-to-<1% mutations (Hazard Ratio = 2.64, 95% confidence interval 1.17-5.95, p = 0.02). Notably, in the whole group of 110 pts, TP53 mutations (any type) occurred more frequently in the intestinal-type GA group (p = 0.02). Conclusions: Additional studies are warranted to explore the favorable role of TP53 mutations in cancer pts undergoing anti-angiogenic therapies. TP53 mutations frequently occur in GA and these findings would lead to novel tailored therapy strategies in this lethal disease.

Sex-Related Differences in Impact on Safety of Pharmacogenetic Profile for Colon Cancer Patients Treated with FOLFOX-4 or XELOX Adjuvant Chemotherapy

Polymorphisms contribute to inter-individual differences and show a promising predictive role for chemotherapy-related toxicity in colon cancer (CC). TOSCA is a multicentre, randomized, non-inferiority, phase III study conducted in high-risk stage II/stage III CC patients treated with 6 vs 3 months of FOLFOX-4 or XELOX adjuvant chemotherapy. During this post-hoc analysis, 218 women and 294 men were genotyped for 17 polymorphisms: TYMS (rs34743033, rs2853542, rs11280056), MTHFR (rs1801133, rs1801131), ERCC1 (rs11615), XRCC1 (rs25487), XRCC3 (rs861539), XPD (rs1799793, rs13181), GSTP1 (rs1695), GSTT1/GSTM1 (deletion +/−), ABCC1 (rs2074087), and ABCC2 (rs3740066, rs1885301, rs4148386). The aim was to assess the interaction between these polymorphisms and sex, on safety in terms of time to grade ≥3 haematological (TTH), grade ≥3 gastrointestinal (TTG) and grade ≥2 neurological (TTN) toxicity. Interactions were detected on TTH for rs1801133 and rs1799793, on TTG for rs13181 and on TTN for rs11615. Rs1799793 GA genotype (p = 0.006) and A allele (p = 0.009) shortened TTH in men. In women, the rs11615 CC genotype worsened TTN (co-dominant model p = 0.008, recessive model p = 0.003) and rs13181 G allele improved the TTG (p = 0.039). Differences between the two sexes in genotype distribution of rs1885301 (p = 0.020) and rs4148386 (p = 0.005) were found. We highlight that polymorphisms could be sex-specific biomarkers. These results, however, need to be confirmed in additional series.

Emerging Biomarkers in Bladder Cancer Identified by Network Analysis of Transcriptomic Data

Bladder cancer is a very common malignancy. Although new treatment strategies have been developed, the identification of new therapeutic targets and reliable diagnostic/prognostic biomarkers for bladder cancer remains a priority. Generally, they are found among differentially expressed genes between patients and healthy subjects or among patients with different tumor stages. However, the classical approach includes processing these data taking into consideration only the expression of each single gene regardless of the expression of other genes. These complex gene interaction networks can be revealed by a recently developed systems biology approach called Weighted Gene Co-expression Network Analysis (WGCNA). It takes into account the expression of all genes assessed in an experiment in order to reveal the clusters of co-expressed genes (modules) that, very probably, are also co-regulated. If some genes are co-expressed in controls but not in pathological samples, it can be hypothesized that a regulatory mechanism was altered and that it could be the cause or the effect of the disease. Therefore, genes within these modules could play a role in cancer and thus be considered as potential therapeutic targets or diagnostic/prognostic biomarkers. Here, we have reviewed all the studies where WGCNA has been applied to gene expression data from bladder cancer patients. We have shown the importance of this new approach in identifying candidate biomarkers and therapeutic targets. They include both genes and miRNAs and some of them have already been identified in the literature to have a role in bladder cancer initiation, progression, metastasis, and patient survival.

Targeting wild-type KRAS-amplified gastroesophageal cancer through combined MEK and SHP2 inhibition

The role of KRAS, when activated through canonical mutations, has been well established in cancer1. Here we explore a secondary means of KRAS activation in cancer: focal high-level amplification of the KRAS gene in the absence of coding mutations. These amplifications occur most commonly in esophageal, gastric and ovarian adenocarcinomas2-4. KRAS-amplified gastric cancer models show marked overexpression of the KRAS protein and are insensitive to MAPK blockade owing to their capacity to adaptively respond by rapidly increasing KRAS-GTP levels. Here we demonstrate that inhibition of the guanine-exchange factors SOS1 and SOS2 or the protein tyrosine phosphatase SHP2 can attenuate this adaptive process and that targeting these factors, both genetically and pharmacologically, can enhance the sensitivity of KRAS-amplified models to MEK inhibition in both in vitro and in vivo settings. These data demonstrate the relevance of copy-number amplification as a mechanism of KRAS activation, and uncover the therapeutic potential for targeting of these tumors through combined SHP2 and MEK inhibition.

MET tyrosine kinase receptor expression and amplification as prognostic biomarkers of survival in gastroesophageal adenocarcinoma

BACKGROUND

MET gene amplification and Met protein overexpression may be associated with a poor prognosis. The MET/Met status is typically determined with fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. Targeted proteomics uses mass spectrometry–based selected reaction monitoring (SRM) to accurately quantitate Met expression. FISH, IHC, and SRM analyses were compared to characterize the prognostic value of MET/Met in gastroesophageal adenocarcinoma (GEC).

METHODS

Samples from 447 GEC patients were analyzed for MET gene amplification (FISH) and Met protein expression (IHC and SRM). Cox proportional hazards models and Kaplan‐Meier estimates were applied to explore relations between Met, overall survival (OS), and clinical/pathological characteristics. Spearman's rank coefficient was used to assess the correlation between parameters.

RESULTS

Patients with MET‐amplified tumors had worse OS when: the MET/centromere enumeration probe for chromosome 7 FISH ratio was ≥ 2 (hazard ratio [HR], 3.13; 95% confidence interval [CI], 1.84‐5.33), the MET gene copy number was ≥5 (HR, 2.51; 95% CI, 1.45‐4.34), or ≥ 10% of the cells had ≥15 copies (HR, 4.28; 95% CI, 2.18‐8.39). Similar observations were made with Met protein overexpression by IHC (≥1 + intensity in ≥ 25% of the tumor cell membrane: HR, 1.39; 95% CI, 1.04‐1.86) or SRM (≥400 amol/μg: HR, 1.76; 95% CI, 1.06‐2.90). A significant correlation was observed between MET FISH/Met IHC, MET FISH/Met SRM, and Met IHC/Met SRM; only MET FISH and Met SRM were independent negative prognostic biomarkers in multivariate analyses.

CONCLUSIONS

MET amplification and overexpression, assessed by multiple methods, were associated with a worse prognosis in univariate analyses. However, only MET amplification by FISH and Met expression by SRM were independent prognostic biomarkers. Compared with IHC, SRM may provide an added benefit for informed decisions about Met‐targeted therapy. Cancer 2017;123:1061–70. © 2016 American Cancer Society.

In a large study, MET gene amplification, Met protein overexpression, or both, as assessed by various assays, are associated with a poor prognosis in univariate analyses. However, only MET amplification by fluorescence in situ hybridization and Met expression by selected reaction monitoring mass spectrometry are independent prognostic biomarkers; compared with immunohistochemistry, selected reaction monitoring may provide an added benefit for informed decisions about Met‐targeted therapy.

Gender effects of single nucleotide polymorphisms and miRNAs targeting clock-genes in metastatic colorectal cancer patients (mCRC)

The circadian system is composed of a set of clock-genes including PERIOD, CLOCK, BMAL1 and CRY. Disrupting this system promotes cancer development and progression. The expression levels of miR-206, miR-219, miR-192, miR-194 and miR-132 regulating clock-genes and three functional polymorphisms rs11133373 C/G, rs1801260 T/C, rs11133391 T/C in CLOCK sequence were associated with the survival of 83 mCRC patients (50 males and 33 females). Longer overall survival (OS) was observed in women compared to men, 50 versus 31 months. This difference was associated with rs11133373 C/C genotype (p = 0.01), rs1801260 T/C+C/C genotype (p = 0.06) and rs11133391 T/T genotype (p = 0.06). Moreover women expressing high levels (H) of miR-192 (p = 0.03), miR-206 (p = 0.003), miR-194 (p = 0.02) and miR-219 (p = 0.002) had a longer OS compared to men. In women longer OS was reinforced by the simultaneous presence of two or more H-miR, 58 months versus 15 months (p = 0.0008); in this group of women an OS of 87 months was reached with the additional presence of rs11133391T/T genotype (p = 0.02). In this study we identified a subgroup of female patients who seems to have a better prognosis. Personalized medicine should prospectively take into account both genetic and gender differences.

Genetic modulation of the interleukin 6 (IL-6) system in patients with advanced gastric cancer: a background for an alternative target therapy

BACKGROUND

IL-6 triggers oncogenic/angiogenic signals and the cytokine-dependent pro-cachexia cascade. The prognostic role of the functional IL-6 (promoter) rs1800795 and the IL-6R (receptor) rs8192284 single nucleotide polymorphisms (SNP) was studied in patients with advanced gastric cancer treated with palliative chemotherapy.

METHODS

One-hundred-sixty-one patients were genotyped for rs1800795 and rs8192284 SNPs using polymerase chain reaction based restriction fragment length polymorphism (PCR-RFLP) analysis assay. These results were studied for association with overall survival (OS).

RESULTS

In 161 assessable patients, frequencies of rs1800795 G/G, G/C and C/C genotypes were 46%, 42% and 12%, respectively. Frequencies of rs8192284 A/A, A/C and C/C genotypes were 36%, 45% and 19%, respectively. Carriers of the rs1800795 G/G and rs8192284 C/C genotypes showed the worst OS. In the multivariate model, rs1800795 G/G (1.69 hazard ratio; 95% confidence interval 1.18-2.42), and rs8192284 C/C (1.78 hazard ratio; 95% confidence interval 1.12-2.83) confirmed an adverse prognostic impact.

CONCLUSIONS

In this population, genetic variants that up-regulate the IL-6 system showed impact on OS. This findings sustain the hypothesis that anti-IL-6 compounds deserve clinical studies as novel therapeutics in the palliative treatment of cancer patients.

Prospective validation of candidate SNPs of VEGF/VEGFR pathway in metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab

PURPOSE

The potential impact of different SNPs of VEGF/VEGFR pathway on the clinical outcome of mCRC patients receiving bev-containing regimens has been investigated in retrospective experiences with contrasting results. We previously reported the association of VEGFA rs833061 C/T variants with PFS in metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab. The primary objective of this work was to prospectively validate that retrospective finding. A confirmatory analysis of other SNPs of VEGF/VEGFR pathway genes was included.

EXPERIMENTAL DESIGN

To detect a HR for PFS of 1.7 for VEGFA rs833061 T/T compared to C- variants in metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab, setting two-sided α = 0.05 and β = 0.20, 199 events were required. VEGFA rs699946 A/G, rs699947 A/C, VEGFR1 rs9582036 A/C and rs7993418 A/G, VEGFR2 rs11133360 C/T, rs12505758 C/T and rs2305948 C/T and EPAS1 rs4145836 A/G were also tested. Germ-line DNA was extracted from peripheral blood. SNPs were analyzed by PCR and sequencing.

RESULTS

Four-hundred-twenty-four pts were included. At the univariate analysis, no differences according to VEGFA rs833061 C/T variants were observed in PFS (p = 0.38) or OS (p = 0.95). Among analyzed SNPs, only VEGFR2 rs12505758 C- variants, compared to T/T, were associated to shorter PFS (HR: 1.36 [1.05-1.75], p = 0.015, dominant genetic model) and OS, with a trend toward significance (HR: 1.34 [0.95-1.88], p = 0.088). In the multivariate model, this association retained significance (HR: 1.405 [1.082-1.825], p = 0.012) in PFS, that was lost by applying multiple testing correction (p = 0.14).

CONCLUSION

This prospective experience failed to validate the hypothesized predictive impact of VEGFA rs833061 variants. Retrospective findings on different candidate SNPs were not confirmed. Only VEGFR2 rs12505758 variants, whose prognostic and not predictive impact was previously reported, correlated with PFS. Given the complexity of angiogenesis, it is rather unlike that a single germ-line SNP might be a good predictor of benefit from bevacizumab.

Period 2 (PER-2) biologic profile in advanced colorectal cancer (ACC) patients (pts)

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Background: Circadian rhythms modulated by clock genes expression as the Period genes (PER-1, PER-2, PER-3) are involved in cancer growth. PER-2 loss in colorectal cancer cell lines and in animal models increases tumorigenesis by β-catenin and cyclin D activation (Wood P, Cancer Res 2008). PER-2 loss in ACC pts was linked to a worse prognosis (Iacobelli S, ASCO 2008). The aim of our study was to identify a PER-2 biological profile related to proliferative indexes and treatment activity. Moreover miRNA related to clock genes were studied as miR-219, target of CLOCK and B-MAL1, miR-206 which affect mammalian circadian clock, miR-132 acting at the SCN level. Methods: We retrospectively evaluated 59 ACC pts, treated with first line chronomodulated triplet combination (Irinotecan+Oxaliplatin+Folinic Acid+5-Fluorouracil) ± Cetuximab. Immunostaining for PER-2, EGFR, ERβ1, ERβ2, Cyclin D1, β-catenin, K-RAS and B-RAF mutations, miRNAs -206, -132, -192, -194, and -219 evaluated on FFPE tumor tissues and their expression levels by quantitative PCR were examined. Results: Clinical data: M/F 32/27; median age 57 y; liver involvment 53%; Cetuximab use: 38%; liver resection: 42%; response to first line chemotherapy: PR 61%, SD 25.4%, PD 10.2%; pts 2.4% not evaluable. Biological data: PER-2 negative (-) /positive (+) 44/56%; EGFR (+)/(-) 54/46%; KRAS wt/mut 75/25%; ERβ1 (-)/(+) 36/65%; ERβ2 (-)/(+) 39/61%; Cyclin D1 (-)/(+) 51/49%; β-catenin(-)/(+) 31/69%. PER-2(-) patients expressed more frequently EGFR (73%) (p>0.0001), ERβ1 (77%) (p=0.07), ERβ2 (88.5%) (p>0.0001), Cyclin D1 (69.2%) (p=0.06) and β-catenin (84.6%) (p=0.02). PER-2(-) was also associated to high miR-206, miR-192 and miR-219 expression. Explorative multiple correspondence analysis showed response to chemotherapy related to a profile including PER-2 (+), EGFR (-), ERβ1 (-), ERβ2 (-), β-catenin (-) and low expression of miR-206. Conclusions: Our data confirmed that: 1) PER-2 loss was associated to activation of cell proliferation confirming in vitro data; 2) PER-2 expression was linked to negative activation of cell proliferation, low miR-206 expression and response to chemotherapy.

Prospective study of EGFR intron 1 CA tandem repeats to predict factor benefit from cetuximab and irinotecan

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Background: Retrospective experiences have investigated the potential influence of EGFR intron 1 CA repeats on the efficacy of cetuximab-containing treatments. Different series, adopting different criteria to define short (S) and long (L) variants, have provided contrasting results. Methods: We designed a prospective confirmatory study, to detect a HR for PFS of 1.75 for L- compared to SS genotypes in a population of KRAS and BRAF wild-type irinotecan-resistant mCRC pts treated with cetuximab and irinotecan. Estimating a prevalence of 60% of the SS variant and setting a two-sided alfa=0.05 with a power of 80%, 104 events were required. We defined S and L allelic variants those presenting < and ≥20 CA repeats, respectively. EGFR (CA)n repeat polymorphism was assessed following a 5’-end [γ-33P] ATP-labeled PCR protocol. Results: One-hundred-fifteen pts were included. At a median follow up of 21.9 months, PFS and OS were 5.2 and 13.4 months, respectively. Thirty-three (29%) out of 114 evaluable pts achieved response. EGFR (CA)n repeat genotype was L- and SS in 45 (40%) and 68 (60%) out of 113 evaluable cases. No differences in PFS or OS were observed between L- and SS genotypes (median PFS: 4.4 vs. 5.3 months, HR: 1.00 [95%CI: 0.67-1.51], p=0.991; median OS: 11.3 vs. 14.2 months, HR: 1.30 [95%CI: 0.80-2.22], p=0.261). Ten (22%) out of 45 L- pts achieved response compared to 22 (33%) out of 67 SS pts (Fisher’s Exact test: p=0.617). Other exploratory analyses adopting different cut-off values reported in literature led to similar results. Conclusions: This prospective study, including a clinically homogenous and molecularly selected population, does not confirm any predictive or prognostic effect for EGFR (CA)n repeat allelic variants with respect to the efficacy of cetuximab and irinotecan in advanced lines of treatment. The present experience strengthens the need of prospectively challenging retrospective findings, as an essential step on biomarkers’ way toward clinical practice.

Prospective evaluation of candidate SNPs of VEGF/VEGFR pathway in metastatic colorectal cancer (mCRC) patients (pts) treated with first-line FOLFIRI plus bevacizumab (BV)

3518

Background: Despite several attempts, no predictors of benefit from BV have been so far identified. We reported the association of VEGF rs833061 T/T to a worse outcome in mCRC pts treated with first-line FOLFIRI+BV, but not in a historical cohort treated with FOLFIRI. Recent post-hoc analyses on randomized trials suggested the potential prognostic and/or predictive role of other VEGF and VEGFR1/2 SNPs. Methods: Moving from our retrospective finding, we designed a prospective validation trial in mCRC pts treated with first-line FOLFIRI+ BV to detect a HR for PFS of 1.7 for VEGF rs833061 T/T compared to C- variants. With two-sided a=0.05 and b=0.20, 199 events were required. Accrual was faster than expected and in the meanwhile promising results about other SNPs were reported and we therefore included a confirmatory analysis of VEGF rs699946 A/G, VEGFR1 rs9582036 A/C and rs7993418 A/G, VEGFR2 rs11133360 C/T, rs12505758 C/T and rs2305948 C/T and EPAS rs4145836 A/G SNPs. Germ-line DNA was extracted from peripheral blood. SNPs were analyzed by PCR and sequencing. Results: Four-hundred-twenty-four pts were included. At a median follow up of 24 months, median PFS was 10.5 months. At the univariate analysis, no differences in PFS according to VEGF rs833061 C/T variants were observed (p=0.38). Among analyzed SNPs, only VEGFR2 rs12505758 C- variants (n=118) were associated to shorter PFS compared to TT (n=306) (HR: 1.40 [95%CI: 1.07-1.84], p=0.015). In the multivariate model, this association retained significance (HR: 1.402 [95%CI:1.079-1.822], p=0.012), that was lost by applying multiple testing correction. Conclusions: This prospective experience failed to validate the hypothesized predictive impact of VEGF rs833061 variants. Also other previous retrospective findings on different candidate SNPs were not confirmed. Only VEGFR2 rs12505758 variants, whose prognostic rather than predictive impact was previously reported, correlated with PFS. We suggest that future studies on biomarkers of benefit from BV should look at the complexity of tumoral angiogenesis at different levels and not only from the genetic perspective.

High let-7a microRNA levels in KRAS-mutated colorectal carcinomas may rescue anti-EGFR therapy effects in patients with chemotherapy-refractory metastatic disease

Preclinical and experimental data in vivo indicate that Lethal-7 (Let-7) microRNA downregulates KRAS with antitumor effects in the presence of activating KRAS mutations. We quantified the Let-7a isoform in KRAS-mutated colorectal carcinomas from patients who received salvage cetuximab plus irinotecan. The study population was retrospectively identified among metastatic colorectal cancer patients who underwent third-line therapy with cetuximab plus irinotecan in a period when only epidermal growth factor receptor (EGFR) expression was required for anti-EGFR therapy. In 59 patients harboring KRAS mutations, Let-7a levels were analyzed for association with overall survival (OS) and progression-free survival (PFS) times. An exploratory subgroup analysis was performed using the rs61764370 (LCS6 T>G) polymorphism that experimentally impairs Let-7 binding to KRAS mRNA. In the whole group, higher Let-7a levels were significantly associated with better survival outcomes. For the primary OS endpoint, the multivariate hazard ratio was 0.82 (95% confidence interval, 0.73-0.91; p = .01). The same findings with an accentuated positive effect of high Let-7a levels on both OS and PFS times were observed in an exploratory analysis of the 45 wild-type LCS6 patients (excluding 14 carriers of the LCS6 G allele variant). All survival associations were confirmed after excluding patients with KRAS codon 13 mutations. Among the clinicopathologic features, high Let-7a levels were associated with grade 2-3 skin toxicity (p = .002). In patients with KRAS mutations, Let-7a analysis may serve to identify subgroups of patients who may still benefit from EGFR inhibition and this may open up new perspectives for alternative treatment strategies.

Genetic activation of the MET pathway and prognosis of patients with high-risk, radically resected gastric cancer

PURPOSE

To investigate whether prognosis of patients with high-risk gastric cancer may depend on MET copy number gain (CNG) or an activating truncation within a deoxyadenosine tract element (DATE) in the promoter region of the MET ligand HGF.

PATIENTS AND METHODS

A single-institution cohort of 230 patients with stage II/III gastric cancer was studied. Formalin-fixed paraffin-embedded tumor specimens were used for DNA extraction. Quantitative polymerase chain reaction (qPCR) for MET CNG and sequencing for HGF DATE truncation (< 25 deoxyadenosines instead of 30) were used. Results were analyzed for association with disease-free survival (DFS) and overall survival (OS). To assess the reliability of the qPCR measurement, a random sample of cases was reanalyzed using an alternative assay (fluorescent in situ hybridization [FISH]) with calculation of the intracorrelation coefficient (ICC).

RESULTS

In 216 assessable patients, MET CNG five or more copies and homozygous HGF-truncated DATE occurred in 21 patients (10%) and 30 patients (13%), respectively. Patients with MET CNG five or more copies (MET-positive) showed significantly worse prognosis with multivariate hazard ratio (HR) of 3.02 (95% CI, 1.71 to 5.33; P < .001) for DFS and multivariate HR of 2.91 (95% CI, 1.65 to 5.11; P < .001) for OS. The agreement between qPCR and FISH was high, with ICC = 0.9% (95% CI, 0.81% to 0.95%; the closer the ICC is to 1, the greater is the agreement). HGF-truncated DATE did not show relevant prognostic effect.

CONCLUSION

In this study, qPCR revealed approximately 10% of white patients with gastric cancer harboring MET CNG of five or more copies. This marker was significantly associated with unfavorable prognosis. This information is relevant to the current clinical development of anti-MET compounds.

Retrospective exploratory analysis of VEGF polymorphisms in the prediction of benefit from first-line FOLFIRI plus bevacizumab in metastatic colorectal cancer

BACKGROUND

Molecular predictors of bevacizumab efficacy in colorectal cancer have not been identified yet. Specific VEGF polymorphisms may affect gene transcription and therefore indirectly influence the efficacy of bevacizumab.

METHODS

Genomic DNA of 111 consecutive metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab was obtained from blood samples. VEGF -2578 C/A, -1498 C/T, + 405 C/G, + 936 C/T polymorphisms were analyzed by means of PCR-RFLP. DNA samples from 107 patients treated with FOLFIRI alone served as historical control group. The relation of VEGF polymorphisms with PFS, evaluated through Kaplan-Meier method and log-rank test, was the primary end-point. An interaction test with a Cox model has been performed in order to demonstrate the heterogeneity of the effect of VEGF -1498 C/T polymorphism between bevacizumab-and control group.

RESULTS

In the bevacizumab-group median PFS and OS of patients carrying VEGF -1498 C/C, C/T and T/T allelic variants were, respectively, 12.8, 10.5, 7.5 months (p = 0.0046, log-rank test) and 27.3, 20.5, 18.6 months (p = 0.038, log-rank test). VEGF -1498 T/T genotype was associated with shorter PFS (HR = 2.13, [1.41-5.10], p = 0.0027). In the control group no significant association of VEGF -1498 C/T allelic variants and PFS or OS was found. Interaction between VEGF -1498 C/T variants and treatment effect suggested that the relation of VEGF -1498 T/T genotype with shorter PFS was caused by the effect of bevacizumab (p = 0.011). Other investigated polymorphisms did not affect the outcome.

CONCLUSIONS

These data suggest a possible role for VEGF -1498 C/T variants in predicting the efficacy of bevacizumab in the up-front treatment of metastatic colorectal cancer patients. A molecular tool for selecting subjects candidate to benefit from the anti-VEGF could be important for clinical practice. The retrospective and exploratory design of the present study, coupled with the non-randomized nature of the comparison between treated and untreated patients, imply that these results should be considered as hypothesis generators. A prospective validating trial is currently ongoing.

Host genetic variants in the IGF binding protein-3 impact on survival of patients with advanced gastric cancer treated with palliative chemotherapy

AIM

IGF binding protein-3 (IGFBP-3) displays growth inhibitory/proapoptotic action and counteracts the IGF-1 tumor-promoting effects by downregulating its bioavailability. We investigated whether IGFBP-3 SNPs determining high IGFBP-3 circulating levels are associated with improved survival of patients with advanced gastric cancer treated with palliative chemotherapy.

MATERIALS & METHODS

A total of 185 patients undergoing combination chemotherapy for relapsed/metastatic disease were considered eligible for the present clinical investigation. Four functional IGFBP-3 SNPs (rs3110697, rs2854746, rs2864744 and rs2960436) were studied for association with overall survival (OS).

RESULTS

In the multivariate model including SNPs and clinicopathologic features, the rs285744 A allele and the rs2960436 A allele showed favorable association with survival. The hazard ratios for rs285744 C/A and A/A genotypes were 0.38 (95% CI: 0.18-0.66) and 0.20 (95% CI: 0.09-0.39), respectively. The hazard ratios for rs2960436 G/A and A/A genotypes were 0.41 (95% CI: 0.25-0.68) and 0.35 (95% CI: 0.16-0.58), respectively. Bonferroni-corrected p-values for the rs285744 A/A genotype and the rs2960436 A/A genotype were 0.012 and 0.024, respectively. There was linkage disequilibrium between the four variants and there were four common haplotypes (>5% estimated frequency). The most common haplotype (GCAA) included all alleles causing IGFBP-3 upregulation and their carriers demonstrated the best outcome in the log-rank comparison of survival curves.

CONCLUSION

Genetic regulation of the IGFBP-3 impacts on survival of patients with advanced gastric cancer. This finding deserves additional studies because of its prognostic and therapeutic implications.

Early magnesium modifications as a surrogate marker of efficacy of cetuximab-based anticancer treatment in KRAS wild-type advanced colorectal cancer patients

BACKGROUND

KRAS wild-type mutational status is necessary but not sufficient to get benefit from epidermal growth factor receptor inhibition. Predictive markers are currently being evaluated. In this study, we investigated early hypomagnesemia as a predictor of efficacy and outcome in terms of time to progression (TtP) and overall survival (OS) in a cohort of patients affected by advanced colorectal adenocarcinoma KRAS wild-type cetuximab-treated.

PATIENTS AND METHODS

One hundred and forty-three patients affected by stage IV colorectal adenocarcinoma KRAS wild type receiving cetuximab + irinotecan (CTX+IRI) as third-line anticancer treatment and resistant to oxaliplatin- and irinotecan-based chemotherapy were retrospectively included. Magnesium plasma levels were measured before the first day and 7, 14, 21 and 28 days after CTX+IRI infusion.

RESULTS

The median magnesium basal value showed a statistically significant decrease after the start of CTX+IRI treatment (at 28 days, P < 0.0001). Patients with an early decrease of magnesium levels >50% compared with the basal level had a higher tumor response rate (55.8% versus 16.7%, P < 0.0001), a longer TtP (6.3 versus 3.6, P < 0.0001) and a longer median OS (11.0 versus 8.1, P = 0.002).

CONCLUSIONS

We have shown that early hypomagnesemia could be a predictor of efficacy and outcome in those patients. Magnesium circulating level is an easy and inexpensive biomarker to routinely be detected in patients treated with cetuximab.

Molecular predictors of efficacy to anti-EGFR agents in colorectal cancer patients

Recent insights into the molecular pathogenesis of colorectal cancer (CRC) have given rise to specific target-directed therapies, including monoclonal antibodies (mAb) against epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF). These drugs have been approved as first, second and third line therapies for metastatic CRC (mCRC) and the advent of target-specific cancer therapeutics has remarkably improved the outcomes of patients with CRC. The molecular mechanisms underlying the clinical response to these drugs are not fully understood, although recent studies have elucidated the effect of intracellular signaling pathways involving in particular RAS/RAF/MAPK signaling on the safety and efficacy of target-specific drugs. Activating mutations of KRAS and BRAF genes are genetic events in tumorigenesis and these mutations are implicated as predictive factors in determining response, in particular to anti-EGFR drugs, and additional data suggest that other EGFR downstream pathways such as PI3K/PTEN/Akt or JAK/STAT are also important when considering mechanisms of EGFR antibody resistance. Recently the European Medical Agency (EMEA) approved the use of the mAb Panitumumab (December 2007) and approved a license extension for the use of the mAb Cetuximab in combination with chemotherapy as first-line treatment (October 2008) in mCRC patients with no mutations in the codon 12 and 13 of KRAS gene. The predictive value of KRAS mutations in the treatment of CRC has been very useful to clinicians and patients in terms of decision making, avoiding toxicities, and decreasing financial burden. This success also encourages researchers to find new markers with the same strong predictive value. Future studies also need to identify patterns of multiple mutations to further increase the power of patient selection for anti-EGFR therapy. These advances allow us to truly enter a new and exciting era of individualized therapy in oncology. Here we review the molecular basis of EGFR-targeted therapies and the resistance to treatments conferred by KRAS and other gene mutations as well as the laboratory methods used to detect all these genetic variations.

Cetuximab plus irinotecan after irinotecan failure in elderly metastatic colorectal cancer patients: clinical outcome according to KRAS and BRAF mutational status

BACKGROUND

Scarce data are available about safety and efficacy of cetuximab in elderly metastatic colorectal cancer (mCRC) patients.

PATIENTS AND METHODS

We retrospectively analysed 54 irinotecan-refractory mCRC patients aged≥70 years treated with cetuximab plus irinotecan and evaluated clinical outcome according to KRAS and BRAF mutational status.

RESULTS

Median age was 73 years (70-82). Main grade 3-4 toxicities were skin rash (15%), diarrhea (19%) and neutropenia (13%). Irinotecan dose reduction was necessary in 39% of patients. Fifty-two (96%) patients were analysed for KRAS and BRAF status. The 29 KRAS wild-type patients achieved better RR (31% vs 4%; p=0.030) and median PFS (4.21 months vs 3.95 months; p=0.034; HR: 0.50, 95% CI: 0.27-0.95) when compared with KRAS mutated ones. RR (41% vs 3%; p=0.001) and mPFS (4.57 months vs 3.78 months, p=0.001; HR: 0.35, 95% CI: 0.19-0.66) were significantly higher among the 22 KRAS and BRAF wild-type patients compared to the 30 KRAS or BRAF mutated ones.

CONCLUSION

Cetuximab plus irinotecan has a favourable safety profile in elderly mCRC patients, but a reduced dose of irinotecan should be considered. Such a combination can be a useful option for elderly KRAS and BRAF wild-type patients.

Genetic modulation of the Let-7 microRNA binding to KRAS 3'-untranslated region and survival of metastatic colorectal cancer patients treated with salvage cetuximab-irinotecan

There is increasing evidence that the Let-7 microRNA (miRNA) exerts an effect as a tumor suppressor by targeting the KRAS mRNA. The Let-7 complementary site (LCS6) T>G variant in the KRAS 3'-untranslated region weakens Let-7 binding. We analyzed whether the LCS6 variant may be clinically relevant to patients with metastatic colorectal cancer (MCRC) treated with anti-epidermal growth factor receptor (EGFR) therapy. LCS6 genotypes and KRAS/BRAF mutations were determined in the tumor DNA of 134 patients with MCRC who underwent salvage cetuximab-irinotecan therapy. There were 34 G-allele (T/G+G/G) carriers (25%) and 100 T/T genotype carriers (75%). G-allele carriers were significantly more frequent in the KRAS mutation group than in patients with KRAS wild type (P=0.004). In the 121 patients without BRAF V600E mutation, overall survival (OS) and progression-free survival (PFS) times were compared between carriers of the LCS6 G-allele genotypes and carriers of the wild-type T/T genotype. LCS6 G-allele carriers showed worse OS (P=0.001) and PFS (P=0.004) than T/T genotype carriers (confirmed in the multivariate model including the KRAS status). In the exploratory analysis of the 55 unresponsive patients with KRAS mutation, LCS6 G-allele carriers showed adverse OS and PFS times. These findings deserve additional investigations as they may open novel perspectives for the treatment of patients with MCRC.

KRAS codon 61, 146 and BRAF mutations predict resistance to cetuximab plus irinotecan in KRAS codon 12 and 13 wild-type metastatic colorectal cancer

Background:

KRAS codons 12 and 13 mutations predict resistance to anti-EGFR monoclonal antibodies (moAbs) in metastatic colorectal cancer. Also, BRAF V600E mutation has been associated with resistance. Additional KRAS mutations are described in CRC.

Methods:

We investigated the role of KRAS codons 61 and 146 and BRAF V600E mutations in predicting resistance to cetuximab plus irinotecan in a cohort of KRAS codons 12 and 13 wild-type patients.

Results:

Among 87 KRAS codons 12 and 13 wild-type patients, KRAS codons 61 and 146 were mutated in 7 and 1 case, respectively. None of mutated patients responded vs 22 of 68 wild type (P=0.096). Eleven patients were not evaluable. KRAS mutations were associated with shorter progression-free survival (PFS, HR: 0.46, P=0.028). None of 13 BRAF-mutated patients responded vs 24 of 74 BRAF wild type (P=0.016). BRAF mutation was associated with a trend towards shorter PFS (HR: 0.59, P=0.073). In the subgroup of BRAF wild-type patients, KRAS codons 61/146 mutations determined a lower response rate (0 vs 37%, P=0.047) and worse PFS (HR: 0.45, P=0.023). Patients bearing KRAS or BRAF mutations had poorer response rate (0 vs 37%, P=0.0005) and PFS (HR: 0.51, P=0.006) compared with KRAS and BRAF wild-type patients.

Conclusion:

Assessing KRAS codons 61/146 and BRAF V600E mutations might help optimising the selection of the candidate patients to receive anti-EGFR moAbs.

Association of BRAF mutations and EGFR Intron-1 L/L genotype with resistance to cetuximab plus irinotecan treatment in KRAS wild-type metastatic colorectal cancer patients

4058

Background: KRAS and BRAF mutations are associated with resistance to anti-EGFR monoclonal antibodies. EGFR Intron-1 (CA)n genotype has been suggested to influence the activity of cetuximab. Methods: We retrospectively assessed KRAS and BRAF mutational status and EGFR Intron-1 (CA)n genotypes in 117 irinotecan-refractory EGFR-positive mCRC patients treated with cetuximab plus irinotecan. We defined short (S) and long (L) allelic variants those presenting < and ≥17 CA repeats respectively. Among KRAS wild-type patients, we investigated the association between BRAF mutational status and EGFR Intron-1 genotype and treatment outcome in terms of RR and PFS. Results: Among 66 (56%) KRAS wild-type patients, BRAF V600E mutation was detected in 9 (14%) patients. BRAF wild-type patients reported improved RR (0/9, 0% vs 19/57, 33%, p = 0.04) and PFS (3.3 vs 5.1 months, p = 0.076; HR = 0.54 [95%CI: 0.18–1.09]) in comparison with BRAF-mutated. EGFR Intron-1 L/L genotype was detected in 13 (20%) KRAS wild-type patients. Objective responses were reported in 1/13 (8%) EGFR Intron-1 L/L patients and in 18/53 (34%) S/L or S/S patients (p = 0.061). Significantly longer PFS was observed among EGFR Intron-1 S/L or S/S patients (5.3 vs 3.3 months, p = 0.0062; HR = 0.45 [95%CI: 0.14–0.72]). Among 57 KRAS and BRAF wild-type patients, 1/11 (9%) EGFR Intron-1 L/L patients and 18/46 (39%) S/L - S/S patients responded to treatment (p = 0.058), achieving median PFS of 3.7 and 5.4 months, respectively (p = 0.022; HR = 0.48 [95%CI: 0.15–0.87]). Conclusions: In KRAS wild-type patients, BRAF mutations are confirmed to predict resistance to cetuximab treatment. EGFR Intron-1 allelic variants are promising markers of benefit in patients with both KRAS and BRAF wild-type and may help to better select mCRC patients candidate to receive cetuximab-containing treatment.

No significant financial relationships to disclose.

Amphiregulin (AR) expression in the prediction of benefit from cetuximab plus irinotecan in KRAS wild-type metastatic colorectal cancer (mCRC) patients

4021

Background: AR is an endogenous ligand of Epidermal Growth Factor Receptor (EGFR), whose binding is prevented in the presence of cetuximab. Methods: We retrospectively assessed KRAS mutational status and AR expression at immunohistochemistry (IHC) in 86 irinotecan-refractory EGFR-positive mCRC patients treated with cetuximab plus irinotecan. AR-IHC was performed on tissue sections from paraffin-embedded primary tumors. Specimens were defined AR-low or AR-high according to a score (range 0–300) obtained multiplying intensity (0 to 3+) by percentage of stained cells (0–100%). According to the results of a ROC analysis, we identified a cut-off value of 18. The association between AR-IHC and treatment outcome in terms of response rate (RR), PFS, and OS was investigated in the subgroup of KRAS wild-type patients. Results: Eighty-six consecutive patients were included. M/F = 44/42, median age = 67 (41–78), median number of previous lines of chemotherapy = 2 (1–5). Among 51 (59%) KRAS wild-type patients, 12 PRs and 1 CR were observed, for an overall RR of 25% (13/51). AR-IHC was high, low or unconclusive in 27, 22 and 2 cases respectively. AR-low patients reported a significantly worse RR (2/22, 9%) compared with AR-high (10/27, 37%) (p = 0.024) and a trend toward shorter PFS (3.5 vs 5.3 months, HR 0.88 [95%CI: 0.46–1.60], p = 0.628) and OS (8.8 vs 15.1 months, HR 0.60 [95%CI: 0.30–1.10], p = 0.106). Conclusions: These results underline the potential role of endogenous ligands in influencing the activity of anti-EGFR monoclonal antibodies. Absent or low AR expression at IHC may be related to resistance to cetuximab plus irinotecan. Further data regarding the prognostic impact of AR expression are needed.

No significant financial relationships to disclose.

NOD2/CARD15 polymorphisms impair innate immunity and increase susceptibility to gastric cancer in an Italian population

In the present case-control study we investigated the potential role of CARD15 R702W, G908R, and 1007fs polymorphisms in Italian gastric cancer patients. The study population consisted of 170 gastric cancer patients and 156 controls. Unconditional regression (odds ratios and 95% confidence interval) was used to investigate the association of the studied polymorphisms with gastric cancer. Higher allele frequencies of R702W and 1007fs polymorphisms were observed in patients with gastric cancer compared with controls (8.53 vs 2.3 and 9.4 vs 0.7, respectively). CARD15 R702W and 1007fs polymorphisms were significantly correlated with gastric cancer incidence (p < 0.0001, p < 0.0001, respectively). No correlation was found upon analyzing the G908R single nucleotide polymorphism (SNP). Our study reports an increased susceptibility to gastric cancer in Italian populations when R702W and 1007fs polymorphisms in the coding region of CARD15 are present. The interaction between NOD-induced proinflammatory cytokines on gastric mucosa and environmental carcinogens could represent one of the mechanisms by which CARD15 polymorphisms increase the susceptibility to gastric cancer. Meta-analyses of these SNPs and further analyses of additional polymorphisms/haplotypes in NOD genes will help determine their role in carcinogenesis.

PTEN expression and KRAS mutations on primary tumors and metastases in the prediction of benefit from cetuximab plus irinotecan for patients with metastatic colorectal cancer

PURPOSE

PTEN, AKT, and KRAS are epidermal growth factor receptor (EGFR) downstream regulators. KRAS mutations confer resistance to cetuximab. This retrospective study investigated the role of PTEN loss, AKT phosphorylation, and KRAS mutations on the activity of cetuximab plus irinotecan in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

A cohort of patients with irinotecan-refractory mCRC who were treated with cetuximab plus irinotecan was tested for PTEN immunoreactivity (ie, immunohistochemistry; IHC), pAKT IHC, and KRAS mutations. Analyses were performed both on primary tumors and on related metastases, and the association among IHC, mutational results, and treatment outcomes was investigated.

RESULTS

One-hundred two patients were eligible. Ninety-six primary tumors, 59 metastases, and 53 paired samples were available. Forty-nine primary tumors (58% of assessable samples) had a preserved PTEN expression (PTEN-positive), whereas 35 (40% of assessable samples) were pAKT-positive. Levels of concordance between primary tumors and metastases were 60%, 68%, and 95% for PTEN, pAKT, and KRAS, respectively. PTEN status on primary tumors and pAKT status both on primary tumors and on metastases did not predict response or progression-free survival (PFS). On metastases, 12 (36%) of 33 patients with PTEN-positive tumors were responders compared with one (5%) of 22 who had PTEN-negative tumors (P = .007). The median PFS of patients with PTEN-positive metastases was 4.7 months compared with 3.3 months for those with PTEN-negative metastases (hazard ratio [HR], 0.49; P = .005). Patients with PTEN-positive metastases and KRAS wild type had longer PFS compared with other patients (5.5 months v 3.8 months; HR, 0.42; P = .001).

CONCLUSION

PTEN loss in metastases may be predictive of resistance to cetuximab plus irinotecan. The combination of PTEN IHC and KRAS mutational analyses could help to identify a subgroup of patients with mCRC who have higher chances of benefiting from EGFR inhibition.