EUSICA/COST IMMUNO-model workshop fostering collaboration to advance sinonasal cancer research: A meeting report

Sinonasal cancer is a clinically and histologically heterogeneous group of rare tumors with generally poor clinical outcomes. Their low incidence hampers the advancement of clinical management as well as translational research, and calls for multicenter and multinational collaboration between physicians and researchers. This report describes the proceedings of a two-day conference organized by the European Network for Sinonasal Cancer Research (EUSICA) and COST Action 'IMMUNO-model', fostering such collaboration and focusing on preclinical tumor and immuno models, surgical and radio-oncological treatments, core facilities for genetic characterization and molecular tumor classification, and cancer registry.

Taxane-induced Attenuation of the CXCR2/BCL-2 Axis Sensitizes Prostate Cancer to Platinum-based Treatment

BACKGROUND

Taxanes are the most active chemotherapy agents in metastatic castration-resistant prostate cancer (mCRPC) patients; yet, resistance occurs almost invariably, representing an important clinical challenge. Taxane-platinum combinations have shown clinical benefit in a subset of patients, but the mechanistic basis and biomarkers remain elusive.

OBJECTIVE

To identify mechanisms and response indicators for the antitumor efficacy of taxane-platinum combinations in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Transcriptomic data from a publicly available mCRPC dataset of taxane-exposed and taxane-naïve patients were analyzed to identify response indicators and emerging vulnerabilities. Functional and preclinical validation was performed in taxane-resistant mCRPC cell lines and genetically engineered mouse models (GEMMs).

INTERVENTION

Metastatic CRPC cells were treated with docetaxel, cisplatin, carboplatin, the CXCR2 antagonist SB265610, and the BCL-2 inhibitor venetoclax. Gain and loss of function in culture of CXCR2 and BCL-2 were achieved by overexpression or siRNA silencing. Preclinical assays in GEMM mice tested the antitumor efficacy of taxane-platinum combinations.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Proliferation, apoptosis, and colony assays measured drug activity in vitro. Preclinical endpoints in mice included growth, survival, and histopathology. Changes in CXCR2, BCL-2, and chemokines were analyzed by reverse transcriptase quantitative polymerase chain reaction and Western blot. Human expression data were analyzed using Gene Set Enrichment Analysis, hierarchical clustering, and correlation studies. GraphPad Prism software and R-studio were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Transcriptomic data from taxane-exposed human mCRPC tumors correlate with a marked negative enrichment of apoptosis and inflammatory response pathways accompanied by a marked downregulation of CXCR2 and BCL-2. Mechanistically, we show that docetaxel inhibits CXCR2 and that BCL-2 downregulation occurs as a downstream effect. Further, we demonstrated in experimental models that the sensitivity to cisplatin is dependent on CXCR2 and BCL-2, and that targeting them sensitizes prostate cancer (PC) cells to cisplatin. In vivo taxane-platinum combinations are highly synergistic, and previous exposure to taxanes sensitizes mCRPC tumors to second-line cisplatin treatment.

CONCLUSIONS

The hitherto unappreciated attenuation of the CXCR2/BCL-2 axis in taxane-treated mCRPC patients is an acquired vulnerability with potential predictive activity for platinum-based treatments.

PATIENT SUMMARY

A subset of patients with aggressive and therapy-resistant prostate cancer benefits from taxane-platinum combination chemotherapy; however, we lack the mechanistic understanding of how that synergistic effect occurs. Here, using patient data and preclinical models, we found that taxanes reduce cancer cell escape mechanisms to chemotherapy-induced cell death, hence making these cells more vulnerable to additional platinum treatment.

Tumor Expression of Cyclin-Dependent Kinase 5 (Cdk5) Is a Prognostic Biomarker and Predicts Outcome of Oxaliplatin-Treated Metastatic Colorectal Cancer Patients

In recent years, an increasing number of studies have shown that elevated expression of cyclin dependent kinase (Cdk5) contributes to the oncogenic initiation and progression of many types of cancers. In this study, we investigated the expression pattern of Cdk5 in colorectal cancer (CRC) cell lines and in a large number of tumor samples in order to evaluate its relevance in this pathogenesis and possible use as a prognostic marker. We found that Cdk5 is highly expressed and activated in CRC cell lines and that silencing of the kinase decreases their migration ability. In tumor tissues, Cdk5 is overexpressed compared to normal tissues due to a copy number gain. In patients with localized disease, we found that high Cdk5 levels correlate with poor prognosis, while in the metastatic setting, this was only the case for patients receiving an oxaliplatin-based treatment. When exploring the Cdk5 levels in the consensus molecular subtypes (CMS), we found the lowest levels in subtype 1, where high Cdk5 again was associated with a poorer prognosis. In conclusion, we confirm that Cdk5 is involved in CRC and disease progression and that it could serve as a prognostic and predictive biomarker in this disease.

Abstract 4369: Plasma metabolomic biomarkers for an early detection of colorectal cancer

The aim of this study was to identify a plasma metabolic pattern characteristic of colorectal cancer (CRC) which could be used to assess the effectiveness of CRC surgery procedures and, eventually, support an early detection on CRC recurrence. CRC survival and treatment depends on accurate staging. In the past few years, numerous efforts have been made to discover new non-invasive biomarkers of CRC to enhance current diagnosis and prognostic capabilities. The metabolome is the result of the interaction of different -omic levels (genomic, epigenomic, transcriptional, proteomic) and the set of external interventions. Metabolites are involved in almost every biochemical reaction in the human body and provide a direct meaningful readout of its dynamic biochemical status. Because of that, metabolomics is a highly relevant approach to explore individual phenotypes in systems biology of cancer. This study reports results obtained from the metabolomic analysis of plasma samples collected from 40 CRC patients (stages I-IV) and 20 healthy controls matched by for age and gender. Blood from 20 matched post-CRC surgery cases (stages I-III) was collected 1-2 years after surgery to evaluate the correlation of changes in the plasma metabolome with surgery effectiveness. Metabolomic and lipidomic analysis was carried out by reversed phase LC-MS. The sample set was split into train (CRC pre-surgery (n=30) and Control (n=15) and test (CRC pre-surgery (n=10), CRC post-surgery (n=20) and Control(n=5)) subsets. The train set was used to build a multivariate model to discriminate CRC pre-surgery and Control groups and the test set was exclusively used to evaluate its generalization performance. Results from this exploratory study showed a statistically significant difference between the metabolic profiles of samples collected pre-CRC surgery and those collected post-surgery and from healthy individuals. Among other metabolites, CRC metabolic profile was characterized by lower levels of tryptophan and several carnitines (propionyl-carnitine, methyl-butirylcarnitine) and isoleucyl-leucine. Finally, our results indicate that these metabolites are at similar level than healthy individuals in post-CRC surgery samples. This cohort included only 2 CRC patients with diagnosed recurrence and 18 recurrence-free patients (stages I-III) within 3-4 years clinical follow-up after surgery and so, more data is required for the estimation of the predictive value of this metabolomic approach for the assessment of the treatment efficiency or disease progression. Conclusions: Our pilot study has identified a pattern of plasma metabolites that correlates with the presence of colorectal tumor. Furthermore, our results indicate that at 1 year post-CRC surgery these metabolites are normalized. Further work is required to establish whether these metabolites could serve as novel disease biomarkers for a minimally invasive diagnosis and monitoring of CRC.

Citation Format: Anna Brunet-Vega, Maria Elisa Quilez, Carles Pericay, Ismael Macias, Laia Vilà, Eva Martinez-Balibrea, Sergio Lario, Guillermo Quintás. Plasma metabolomic biomarkers for an early detection of colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4369.

Epigenetic Homogeneity Within Colorectal Tumors Predicts Shorter Relapse-Free and Overall Survival Times for Patients With Locoregional Cancer

BACKGROUND & AIMS

There are few validated biomarkers that can be used to predict outcomes for patients with colorectal cancer. Part of the challenge is the genetic and molecular heterogeneity of colorectal tumors not only among patients, but also within tumors. We have explored intratumor heterogeneity at the epigenetic level, due to its dynamic nature. We analyzed DNA methylation profiles of the digestive tract surface and the central bulk and invasive front regions of colorectal tumors.

METHODS

We determined the DNA methylation profiles of >450,000 CpG sites in 3 macrodissected regions of 79 colorectal tumors and 23 associated liver metastases, obtained from 2 hospitals in Spain. We also analyzed samples for KRAS and BRAF mutations, 499,170 single nucleotide polymorphisms, and performed immunohistochemical analyses.

RESULTS

We observed differences in DNA methylation among the 3 tumor sections; regions of tumor-host interface differed the most from the other tumor sections. Interestingly, tumor samples collected from areas closer to the gastrointestinal transit most frequently shared methylation events with metastases. When we calculated individual coefficients to quantify heterogeneity, we found that epigenetic homogeneity was significantly associated with short time of relapse-free survival (log-rank P = .037) and short time of overall survival (log-rank P = .026) in patients with locoregional colorectal cancer.

CONCLUSIONS

In an analysis of 79 colorectal tumors, we found significant heterogeneity in patterns of DNA methylation within each tumor; the level of heterogeneity correlates with times of relapse-free and overall survival.

Tumor-Related Molecular Mechanisms of Oxaliplatin Resistance

Oxaliplatin was the first platinum drug with proven activity against colorectal tumors, becoming a standard in the management of this malignancy. It is also considered for the treatment of pancreatic and gastric cancers. However, a major reason for treatment failure still is the existence of tumor intrinsic or acquired resistance. Consequently, it is important to understand the molecular mechanisms underlying the appearance of this phenomenon to find ways of circumventing it and to improve and optimize treatments. This review will be focused on recent discoveries about oxaliplatin tumor-related resistance mechanisms, including alterations in transport, detoxification, DNA damage response and repair, cell death (apoptotic and nonapoptotic), and epigenetic mechanisms.

Abstract 2829: Identification of the role of SRBC methylation-associated gene silencing as predictive factor of oxaliplatin secondary resistance in metastasic colorectal cancer patients

Background: Resistance acquisition to chemotherapeutic agents is one of the main problems that come up during cancer treatment. The mechanisms of developing resistance are poorly understood, and the causes underlying the loss of sensitivity to common chemotherapy drugs, like oxaliplatin, are largely unknown. The importance of epigenetic alterations has long been demonstrated in cancer. Several studies have shown that promoter methylation-associated silencing inactivates tumor suppressor genes (TSGs) as effectively as mutations and is one of the cancer-predisposing hits described in Knudson's two hit hypothesis. SRBC gene is a TSG the inactivation of which has been associated with malignant tumor progression, being involved in membrane traffic, cell cycle, proliferation, apoptosis and DNA damage mechanisms. In a previous work, we demonstrated the involvement of SRBC methylation-associated expression silencing in oxaliplatin resistance acquisition by using in vitro models and functional analysis. Thus, in the present work, we propose to investigate the role of SRBC promoter methylation alterations as potential predictive biomarker of oxaliplatin chemoresistance in metastasic CRC (mCRC) patients.

Material and methods: By Methylation-Specific PCR and pyrosequencing, we analysed SRBC promoter methylation in two independent cohorts of 131 and 58 primary tumors from mCRC patients treated with 5FU-oxaliplatin combination. Chi-square and Fisher test were used to assess the categorical variables associations. Kaplan-Meier plots and Log-Rank test were used to estimate progression-free survival (PFS). The association between gene methylation and clinical parameters with PFS was assessed through univariate and multivariate Cox proportional hazards regression models. We considered statistically significant a two-sided p-value (P) lower than 0.05.

Results: SRBC epigenetic inactivation occurred in primary tumors from a discovery cohort of colorectal cancer patients (29.8%, 39 of 131), where it predicted shorter PFS (HR = 1.83; 95% CI = 1.15-2.92; Log-Rank P= 0.01), particularly in oxaliplatin-treated cases for which metastasis surgery was not indicated (HR = 1.96; 95% CI = 1.13-3.40; Log-Rank P= 0.01). In a validation cohort of unresectable metastases colorectal tumors treated with oxaliplatin (n=58), SRBC hypermethylation was also associated with shorter PFS (HR = 1.90; CI= 1.01-3.60; Log-Rank P= 0.045).

Conclusions: Remarkably, SRBC promoter hypermethylation was related to worse PFS rate in mCRC patients with unresectable liver metastasis who received 5FU-oxaliplatin based treatment. These results provide a basis for future clinical studies to validate SRBC hypermethylation as a predictive marker for oxaliplatin resistance in mCRC patients.

Citation Format: Anna Martinez-Cardus, Catia Moutinho, Cristina Santos, Valentin Navarro-Perez, Eva Martinez-Balibrea, Eva Musulen, Francisco Javier Carmona, Andrea Sartore-Bianchi, Andrea Cassingena, Salvatore Siena, Elena Elez, Josep Tabernero, Ramon Salazar, Albert Abad, Manel Esteller. Identification of the role of SRBC methylation-associated gene silencing as predictive factor of oxaliplatin secondary resistance in metastasic colorectal cancer patients. [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 2829. doi:10.1158/1538-7445.AM2014-2829

Abstract 3752: PKM2 subcellular localization is involved in oxaliplatin resistance acquisition in human colorectal cancer cell lines

Background/purpose: Despite remaining one of the most active drugs in the treatment of advanced colorectal cancer (aCRC), oxaliplatin (OXA) resistance still is a multifactorial and complex process to decipher. In a previous work we identified low levels of PKM2 (mRNA and protein) as a putative OXA-resistance marker in CRC cell lines and patients. The purpose of this work was to identify molecular mechanisms underlying PKM2 role in resistance to OXA.

Material and methods: PKM2 transient gene silencing was achieved by transfecting specific siRNAs (Ambion) in HT29 and HCT116 CRC cell lines. Gene silencing was validated by qPCR and Western Blot with specific Taqman primers and probes (assay no. Hs00762869_s1) and antibody (Cell signaling), respectively. Cell proliferation was measured by the MTT assay (Roche Diagnostics). Inhibitory concentrations were determined in each cell line by the median-effect line method. Cell viability was studied with the use of trypan blue stain and apoptosis was detected with FITC Annexin V Apoptosis Detection Kit I (BD Pharmingen). PKM2 subcellular localization was studied by fluorescence microscopy in an Axiovision Z1 by using Apotome system at 40x immersion oil lens (Carl Zeiss, Heidelberg, Germany). Expression patterns of cell death genes were analyzed through Human Cell Death Pathway Finder PCR Array 384 HT (PAHS-212Z, SA Biosciences).

Results: In order to assess how PKM2 expression influences OXA response in CRC cells, we silenced PKM2 by using specific siRNAs in HT29 and HCT116 cells. Cells were then treated with OXA at different concentrations and we observed that PKM2 silencing induced resistance in HT29 (p53 mutated) cells and sensitivity in HCT116 (p53 wild type) cells. Moreover, PKM2 knockdown was associated with an increase in cell viability but not with a decrease in apoptosis activation in HT29 cells. Fluorescence microscopy revealed PKM2 nuclear translocation in response to OXA in HCT116 and HT29 cells but not in OXA-resistant HTOXAR3 cells. Finally, by using a qPCR Array we demonstrated that OXA and PKM2 silencing altered cell death gene expression patterns including BMF, which was significantly increased in HT29 cells in response to OXA in a dose and time-dependent manner but not in siPKM2-HT29 and HTOXAR3 cells.

Conclusion: Our data report new non-glycolytic roles of PKM2 in response to genotoxic damage, which depend on p53 mutational status and proposes BMF as a possible target gene of PKM2 to be involved in OXA response and resistance in CRC cells.

Citation Format: Alba Ginés, Anna Martínez-Cardús, Vicenç Ruiz de Porras, Eva Musulén, José Luis Manzano, Laura Layos, Cristina Bugés, Albert Abad, Eva Martinez-Balibrea. PKM2 subcellular localization is involved in oxaliplatin resistance acquisition in human colorectal cancer cell lines. [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 3752. doi:10.1158/1538-7445.AM2014-3752

A DERL3-associated defect in the degradation of SLC2A1 mediates the Warburg effect

Cancer cells possess aberrant proteomes that can arise by the disruption of genes involved in physiological protein degradation. Here we demonstrate the presence of promoter CpG island hypermethylation-linked inactivation of DERL3 (Derlin-3), a key gene in the endoplasmic reticulum-associated protein degradation pathway, in human tumours. The restoration of in vitro and in vivo DERL3 activity highlights the tumour suppressor features of the gene. Using the stable isotopic labelling of amino acids in cell culture workflow for differential proteome analysis, we identify SLC2A1 (glucose transporter 1, GLUT1) as a downstream target of DERL3. Most importantly, SLC2A1 overexpression mediated by DERL3 epigenetic loss contributes to the Warburg effect in the studied cells and pinpoints a subset of human tumours with greater vulnerability to drugs targeting glycolysis.

Genetic markers of toxicity from capecitabine and other fluorouracil-based regimens: investigation in the QUASAR2 study, systematic review, and meta-analysis

PURPOSE

Fluourouracil (FU) is a mainstay of chemotherapy, although toxicities are common. Genetic biomarkers have been used to predict these adverse events, but their utility is uncertain.

PATIENTS AND METHODS

We tested candidate polymorphisms identified from a systematic literature search for associations with capecitabine toxicity in 927 patients with colorectal cancer in the Quick and Simple and Reliable trial (QUASAR2). We then performed meta-analysis of QUASAR2 and 16 published studies (n = 4,855 patients) to examine the polymorphisms in various FU monotherapy and combination therapy regimens.

RESULTS

Global capecitabine toxicity (grades 0/1/2 v grades 3/4/5) was associated with the rare, functional DPYD alleles 2846T>A and *2A (combined odds ratio, 5.51; P = .0013) and with the common TYMS polymorphisms 5'VNTR2R/3R and 3'UTR 6bp ins-del (combined odds ratio, 1.31; P = 9.4 × 10(-6)). There was weaker evidence that these polymorphisms predict toxicity from bolus and infusional FU monotherapy. No good evidence of association with toxicity was found for the remaining polymorphisms, including several currently included in predictive kits. No polymorphisms were associated with toxicity in combination regimens.

CONCLUSION

A panel of genetic biomarkers for capecitabine monotherapy toxicity would currently comprise only the four DPYD and TYMS variants above. We estimate this test could provide 26% sensitivity, 86% specificity, and 49% positive predictive value-better than most available commercial kits, but suboptimal for clinical use. The test panel might be extended to include additional, rare DPYD variants functionally equivalent to *2A and 2846A, though insufficient evidence supports its use in bolus, infusional, or combination FU. There remains a need to identify further markers of FU toxicity for all regimens.

hSRBC promoter CpG island hypermethylation as resistant predictive biomarker of oxaliplatin based chemotherapy in metastasic colorectal cancer patients

e14609

Background: Resistance acquisition to chemotherapeutic agents is one of the main problems that come up during cancer treatment. hSRBC is a tumor suppressor gene whose inactivation has been associated with malignant tumor progression. In a previous work, we investigated the influence of hSRBC promoter methylation alterations in oxaliplatin (OXA) resistance acquisition by using a CRC “in vitro” model, detecting an hSRBC promoter hypermethylation in OXA–resistant derived cells when compared with the sensitive counterpart. These results were validated by functional analyses in the same model. Taking this into account, our aim in the present work is to determine the role of hSRBC methylation status as a potential biomarker of OXA resistance, in metastatic CRC patients, treated at first line with fluouropirimidines plus OXA based chemotherapy. Methods: hSRBC promoter hypermethylation was analyzed in DNA extracted from paraffin embebbed tissue of 111 metastatic CRC tumors by using Methylation Specific PCR. Methylation data was correlated to overall response (OR) and progression free survival (PFS) by using F-Fisher test and Kaplan-Meyer Survival curves respectively. A multivariate analysis was carried out by Cox regression. p-values under 0.05 were considered statistic significant. Results: Two independent cohorts of stage IV CRC tumors were included. Twenty-two out of 111 patients received radical surgery for metastasis, that became to be a positive prognostic factor (p-value = 0.04). Gene hypermethylation was detected in a 33% of cases. Although OR was not associated with hSRBC methylation, we observed a significant correlation between hypermethylation of gene and a worse PFS in patients without metastasis surgery (Log Rank; p-value = 0.04). Conclusions: Remarkably, hSRBC promoter hypermethylation is associated with worse PFS in metastatic CRC patients. We suggest hSRBC methylation status as a predictive biomarker of OXA-based treatment outcome in metastatic CRC patients. However, further studies are warranted in order to elucidate the clinical application of these findings.

Soluble FAS in the prediction of benefit from cetuximab and irinotecan for patients with advanced colorectal cancer

The FAS/FASL system, comprising membrane-bound (mFAS and mFASL) and soluble forms (sFAS and sFASL), has been related to apoptosis driven by chemotherapy administration. In vitro experiments show chemotherapy upregulating membrane-bound forms, leading to an increase of receptor availability (at 24-72 h) and favoring apoptosis. The regulatory effect of chemotherapy on sFAS in patients has never been explored prospectively in advanced colorectal cancer (ACRC). We performed a pharmacodynamic study to address sFAS/sFASL variation. A prospective phase II translational multicenter study was designed to evaluate progression-free rate (PFR) in patients with ACRC treated with irinotecan and cetuximab in third-line therapy. The effect of sFAS was studied in vitro in colorectal cancer cell lines. Our results showed that statistically significant changes were observed in sFAS at 24-72 h compared to baseline levels in the pharmacodynamic study. Of the 93 patients enrolled in the prospective study in third-line therapy with cetuximab-irinotecan, 85 were evaluated for sFAS/sFASL changes at 48 h. There was no difference in PFR at 4 months between patients with sFAS and sFASL changes. In vitro analysis showed that although LoVo cell lines were sensitive to oxaliplatin and fluorouracil due to modulation of sFAS and FAS, HT29 lines were not. In summary, chemotherapy regulates FAS soluble fractions in vitro and in vivo, but does not predict PFR in ACRC patients undergoing third-line therapy with the combination of cetuximab and irinotecan.

Polymorphisms in genes OPRM1, β-arrestin 2, STAT6, and COMT and clinical outcome to opioid therapy

9129

Background: Morphine sulfate is the most widely used opioid in oncologic pain. There is a high variability in response between individuals. The objectives are to correlate the variability in response (R) and tolerability with polymorphisms within OPRM1, β-arrestin 2, STAT6 and COMT gene sequences. Methods: DNA from 44 oncologic patients (pts) with an EVA score > 6 was prospectively analyzed using allelic discrimination techniques and automatic sequencing. Pts (never treated with opioids) received morphine sulfate 10 mg per day. Pain was assessed by EVA score and toxicity was evaluated according to the most common opioid side effects. Symptomatology was reassessed after 72 hours. Chi-squared and Fisher’s tests where used to analyze data. Results: 17 pts (38.6%) responded with an EVA < 3. 6 pts (13.6%) did not experience toxicity, 36 pts (81.8%) had mild side effects and 2 pts (4.5%) had severe side effects. There was no relation between R rate (RR) and tolerance. 76.5% of pts responding to treatment had a CC/CT β-arrestin 2 genotype and this was associated with a better RR (CC/CT R = 46.4% vs. TT R = 25% p = 0.16). The 2 pts having severe side effects belonged to CC/CT group. COMT genotypes AA/GA were associated with a higher RR (83.3%pts) and better tolerance (100% pts with no toxicities). OPRM1 genotype GG was associated with both treatment failure (0% responded) and worse tolerance (any toxicity = 100%; severe side effects = 33%). Only 2,4% pts in the AA/GA genotype experienced some toxicity (p = 0.041). Although STAT6 genotypes were not associated with RR, tolerance was better in those pts with an AA or GA genotype with 97.5% pts showing either mild or no side effects (p = 0.007). Conclusions: Common variants in β-arrestin 2, COMT, OPRM1 and STAT6 genes have shown to predict for opioid-associated response and side effects in oncologic patients. Further studies are needed to assess factors determining the variability in response and tolerance to opioid treatment.

ERCC1 and ERCC2 polymorphisms predict clinical outcomes of oxaliplatin-based chemotherapies in gastric and colorectal cancer: a systemic review and meta-analysis

PURPOSE

Nucleotide excision repair (NER) modulates platinum-based chemotherapeutic efficacy by removing drug-produced DNA damage. To summarize published data on the association between polymorphisms of NER genes (ERCC1 and ERCC2) and responses to oxaliplatin-based chemotherapies, we carried out a meta-analysis of gastric and colorectal cancer for commonly studied polymorphisms ERCC1 rs11615C>T and ERCC2 rs13181T>G.

PATIENTS AND METHODS

In 17 previously published studies, 1,787 cancer patients were treated with the oxaliplatin-based regimen. Primary outcomes included therapeutic response (TR; i.e., complete response + partial response vs. stable disease + progressive disease), progression-free survival (PFS), and overall survival (OS). We calculated OR or HR with 95% CIs to estimate the risk or hazard.

RESULTS

We found consistent and clinically substantial risk or hazard for TR, PFS, and OS in the oxaliplatin-treated gastric and colorectal cancer patients with an ethnic discrepancy. For ERCC1 rs11615C>T, the T allele was associated with reduced response and poor PFS and OS in Asians (TR: OR = 0.53 and 95% CI = 0.35-0.81; PFS: HR = 1.69 and 95% CI = 1.05-2.70; and OS: HR = 2.03 and 95% CI = 1.60-2.59). For ERCC2 rs13181T>G, the G allele was associated with reduced response and poor PFS and OS in Caucasians (TR: OR = 0.56 and 95% CI = 0.35-0.88; PFS: HR = 1.41 and 95% CI = 1.02-1.95; and OS: HR = 1.42 and 95% CI = 1.11-1.81).

CONCLUSIONS

NER ERCC1 rs11615C>T and ERCC2 rs13181T>G polymorphisms are useful prognostic factors in oxaliplatin-based treatment of gastric and colorectal cancer. Larger studies and further clinical trials are warranted to confirm these findings.

Abstract 2610: TYMS and XRCC1 gene polymorphisms as possible predictors for the addition of oxaliplatin to 5FU in the adjuvant treatment of stage II and III colorectal cancer

Background: The MOSAIC trial demonstrated that adding oxaliplatin to LV5FU2 significantly improved 5-year disease free survival (DFS) and 6-year overall survival (OS) in the adjuvant treatment of stage II/III colorectal cancer (CRC). However, oxaliplatin-related toxicities represent a problem when managing these patients. Genetic variants in TYMS and XRCC1 have shown to influence patients' outcomes in the metastatic setting. The purpose of the present study was to evaluate the influence of these polymorphisms on DFS and OS of stage II/III CRC patients treated with LV5FU2 +/- oxaliplatin in an adjuvant setting. Methods: We genotyped 216 patients (53.7% LV5FU2 and 46.3% FOLFOX4) from the MOSAIC trial. TYMS polymorphisms (5′TRP and 5′UTR SNP) and XRCC1-Arg399Gln were analyzed through PCR, RFLP and allelic discrimination respectively. According to TYMS 5′UTR SNP, genotypes were grouped as low expression (2R/2R, 2R/3RC, 3RC/3RC) or high expression (2R/3RG, 3RC/3RG, 3RG/3RG). Association of genetic variants with DFS and OS was investigated through Kaplan Meyer curves, log rank test and Cox regression models. Results: In our cohort 57.5% of patients were males; median age was 61 years (33-79); stage II/III tumors were equally distributed (50.2% and 49.8%). After 6 years of follow-up, 20.4% (38.6% FOLFOX4, 61.4% LV5FU2) of patients had relapsed and 15.4% (42.4% FOLFOX4, 57.6% LV5FU2) were dead. There were no statistical significant differences in DFS or OS according to individual genetic variants either in the whole group or by treatment. Therefore, they were analyzed jointly. TYMS high expression genotypes were considered as non-favorable for 5FU and XRCC1-399 Gln/Gln or Arg/Gln genotypes were considered as non-favorable for oxaliplatin. Patients in the FOLFOX4 group with non-favorable genotypes were more likely to relapse (28% vs. 11% for some favorable genotype; HR=2.7, 95% CI 1.00-7.34; Log rank p=0.04) or dying (17% vs. 5% for some favorable genotype; HR=2.7, 95% CI 0.92-8.17; Log rank p=0.06). Interestingly, these phenomena didn't occur in the LV5FU2 group of patients. Taken together, patients with some favorable genotype had better outcomes when receiving FOLFOX4 (87% vs. 78% for DFS, HR=0.63, 95% CI 0.28-1.43; p=0.07 and 95% vs. 89% for OS, HR=0.56, 95% CI 0.27-1.15; p=ns) after 6 years of follow-up. Inversely, FOLFOX4 was detrimental for those patients with non-favorable genotypes as compared with patients receiving LV5FU2 (68% vs. 78% for DFS, HR=2.5, 95% CI 0.60-11.1; p=ns and 83% vs. 89% for OS, HR=1.27, 95% CI 0.41-4; p=ns). Conclusion: TYMS 5′UTR SNP and XRCC1 Arg399Gln genotyping could help in the decision of adding or not oxaliplatin to LV5FU2 as adjuvant treatment in patients with stage II/III CRC and thus avoid undesirable oxaliplatin-related toxicities to these patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2610.

Abstract 2562: Role of Pyruvate Kinase isozyme type M2 in response and resistance to oxaliplatin in HT29 human colon adenocarcinoma cell lines

BACKGROUND: Resistance to platinum-based chemotherapy is a multifactorial and complex process resulting in a major obstacle for effective treatment. In a previous work we identified low levels of PKM2 (mRNA and protein) as a putative oxaliplatin-resistance marker by using an in vitro model of resistance and a comparative proteomic approach. Our results were also validated in advanced colorectal cancer patients treated with oxaliplatin (Martinez-Balibrea, Molecular cancer therapeutics, 2009). PKM2 has been reported to translocate to the nucleus and activate apoptosis after H2O2, UV or a somatostatin analog treatment. The aim of this work was to study the role of PKM2 in the molecular mechanisms involved in response and resistance to oxaliplatin and identify proteins related to PKM2 expression levels. EXPERIMENTAL DESIGN: We silenced PKM2 expression by using siRNA techniques in the human adenocarcinoma cell line HT29. Validation of knockdown was done by Western Blotting (WB) and RTQPCR. To study the effect of PKM2 silencing in the resistance phenotype an MTT assay was performed to compare the viability between PKM2-silenced cells and those transfected with an unspecific siRNA (NTC). Cells were treated 24 hours with oxaliplatin at 15 µM. To verify the PKM2 nuclear translocation and its possible role in activating apoptosis after H2O2 and oxaliplatin treatment, HT29 and HCT116 cells were treated with H2O2 and oxaliplatin at equivalent doses and harvested at 0, 2 and 4h after treatment. Sub-cellular fractionation and WB as well as immunoflorescenece techniques were performed to visualize nuclear translocation of PKM2. To study possible changes in the proteome of HT29 cells as a consequence of PKM2 silencing, 2D- DIGE and Mass Spectrometry techniques were performed. RESULTS: Forty-eight hours after transfection we obtained a 95% of PKM2 knockdown by RTQPCR (mRNA level) and also by WB (protein level). A slightly increase of viability was observed in PKM2-silenced cells in comparison to NTC cells after oxaliplatin exposition (50% vs. 35%). Preliminary results showed that both oxaliplatin and H2O2 induced PKM2 nuclear translocation in HT29 and HCT116 cells 4 hours after the exposition to these agents. By 2D-DIGE we determined changes in the proteome of HT29 cells as a consequence of PKM2 silencing. The identification and validation of those proteins showing up- or down-regulation are in process and will be presented during the annual meeting. CONCLUSIONS: PKM2 knockdown alters sensitivity to oxaliplatin and protein expression patterns in HT29 cells. Oxaliplatin induces nuclear translocation of PKM2. Further studies are guaranteed to evaluate the role of PKM2 in activating apoptosis after oxaliplatin exposure.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2562.

A proteomic approach links decreased pyruvate kinase M2 expression to oxaliplatin resistance in patients with colorectal cancer and in human cell lines

We aimed to gain further understanding of the molecular mechanisms involved in oxaliplatin resistance in colorectal cancer by using a proteomic approach. A 5-fold oxaliplatin-resistant cell line, HTOXAR3, was compared with its parental cell line, HT29, using two-dimensional PAGE. Mass spectrometry, Western blot, and real-time quantitative PCR confirmed the down-regulation of pyruvate kinase M2 (PK-M2) in HTOXAR3 cells. In a panel of eight colorectal cancer cell lines, we found a negative correlation between oxaliplatin resistance and PK-M2 mRNA levels (Spearman r=-0.846, P=0.008). Oxaliplatin exposure in both HT29 and HTOXAR3 led to PK-M2 mRNA up-regulation. PK-M2 mRNA levels were measured by real-time quantitative PCR in 41 tumors treated with oxaliplatin/5-fluorouracil. Tumors with the lowest PK-M2 levels attained the lowest response rates (20% versus 64.5%, P=0.026). High PK-M2 levels were associated with high p53 levels (P=0.032). In conclusion, the data provided clearly link PK-M2 expression and oxaliplatin resistance mechanisms and further implicate PK-M2 as a predictive marker of response in patients with oxaliplatin-treated colorectal cancer.

Increased levels of copper efflux transporter ATP7B are associated with poor outcome in colorectal cancer patients receiving oxaliplatin-based chemotherapy

Recently, the copper efflux transporters ATP7B and ATP7A have been implicated in the transport of and resistance to platinum drugs in breast and ovarian cancers. Because of the extensive use of oxaliplatin in colorectal cancer (CRC), we examined the expression of both transporters in tumors from CRC patients treated with oxaliplatin/5FU and sought to determine whether their expression can predict clinical outcome in these patients. ATP7B and ATP7A levels were determined by quantitative real-time PCR in 50 primary tumors of previously untreated patients with advanced colorectal adenocarcinoma who were subsequently treated with oxaliplatin/5FU. Additionally, ATP7B protein expression was assessed by immunohistochemical staining using a tissue microarray. Patients with the lowest mRNA expression levels of ATP7B had a significantly longer time to progression (TTP) (p = 0.0009) than patients with the highest levels (12.14 months vs. 6.43 months) who also had an increased risk of progression (HR = 3.56; 95% CI, 1.6-7.9; p = 0.002). Furthermore, patients with low levels of both protein and mRNA of ATP7B derived the maximum benefit from oxaliplatin/5FU with the longest TTP as compared with patients with high levels of ATP7B protein and mRNA (14.64 months vs. 4.63 months, respectively, p = 0.01) and showed a nonsignificant trend toward a lower response rate (37.5% and 75%, respectively). In conclusion, ATP7B mRNA and protein expression in colorectal tumors is associated with clinical outcome to oxaliplatin/5FU. Prospective studies are required to evaluate the role of this marker in tailoring chemotherapy.

Pharmacogenetic analysis of TS and UGT1A polymorphisms predictive for response and toxicity in Spanish patients with advanced colorectal cancer treated with first-line irinotecan and 5-fluorouracil

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Background: The possible role of uridine diphosphate-glucuronosyltransferase 1A (UGT1A) and Thymidylate Synthase (TS) gene polymorphisms in predicting toxicity and outcomes in irinotecan/ 5-Fluorouracil (5FU)-treated patients is still controversial. The aim of this work was to determine whether UGT1A1, UGT1A7, and UGT1A9 as well as TS polymorphisms affect toxicities and/or outcomes of Spanish patients with advanced colorectal cancer (mCRC) Methods: A total of 149 patients with mCRC were treated either with weekly irinotecan plus high-dose 5FU (FUIRI) or biweekly irinotecan plus 5FU/Leucovorin (FOLFIRI) as first-line chemotherapy (Aranda E; Ann Oncol. 2008 Aug 20). Genomic DNA was extracted from peripheral blood and genotyped using allelic discrimination and direct sequencing. Chi-square test, Fisher's exact test and logistic regression were used to study the association of genotypes with toxicity and response. Log rank and cox regression were used in survival analysis. All statistical tests were two-sided. Results: According to TS 5’TRP genotypes, 79.3% of the 2R/2R patients responded to therapy while only 52.5% of 2R/3R or 3R/3R patients do so (HR=3.5; 95% CI=1.3- 9.1; p=0.009). TS genotypes were not associated with toxicity. UGT1A1*28 TA7/TA7 genotype was clearly associated with severe toxicity (HR=12.7; 95% CI=3.1–51.3; p=0.001) and diarrhea (HR=4; 95% CI=1.3–12; p=0.016) when compared to TA6/TA7 and TA6/TA6 genotypes. These patients also experienced more severe neutropenia (40% vs. 18.8%, p=0.087) and more frequent dose reductions (53.3% vs. 38.1%, p=ns). UGT1A7*3/*3 and UGT1A9–118(dT)9/9 were associated with severe diarrhea (50% vs. 27% p=0.032 and 43% vs. 23% p=0.012). When all non-favourable genotypes (TA7/TA7, *3/*3 and 9/9) were taken into account, there was a statistically significant association with severe diarrhea (HR=4.5; 95% CI 1.3–16.3; p=0.021), neutropenia (HR=3.5; 95% CI=1–12.7; p=0.047) and both (HR=12.4; 95% CI=2.8–54.2; p=0.001). Conclusions: Our data clearly link UGT1A genotypes with irinotecan-related severe toxicity. TS 5’TRP genotypes are predictive of response to irinotecan/5FU first-line chemotherapy.

No significant financial relationships to disclose.

In vitro-acquired resistance gene expression profile and in vivo response to oxaliplatin-based treatment

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Background: Resistance to oxaliplatin is one of the main problems of colorectal cancer (CRC) treatment success. It is not clear if intrinsic and acquired resistance processes are developed by related mechanisms. In a previous work (Martinez-Cardús et al. Mol Cancer Ther, January 2009), we determined a profile of oxaliplatin-acquired resistance related genes by using an in vitro model. In the present work, we analyzed this genetic profile in paraffin-embedded primary adenocarcinomas from CRC patients treated with oxaliplatin-fluoropyrimidine. mRNA expression data was correlated with response rate and time to progression (TTP) in order to determine the role of these genes as markers of resistance to oxaliplatin-based treatment. Material and Method: mRNA levels were analyzed by using Real Time PCR. β-actin and 18s were used as housekeeping genes and, as a reference sample, we used commercial pool of mRNA from different human tumours. Chi- square and Fisher test were used in order to value differences in response rate to treatment. TTP was studied by using Kaplan Meyer curves and Log rank test. Median and percentile 33 and 66 were used as threshold values to determine both high and low expression level groups for each gene analyzed. We considered statistically significant a two-sided p-value lower than 0.05. Results: Forty-four advanced CRC patients treated with fluoropyrimidine plus oxaliplatin were analyzed. 54.5% of them were males; primary tumour was localized in colon in a 65.9% of cases. According to qRT-PCR analysis, the in vitro oxaliplatin acquired resistance related genes could be detected in the tumours but the expression of any of them correlated significantly with in vivo resistance to oxaliplatin-based treatment by using the three different threshold values to define groups. Conclusions: According to our results, these genes could not be used as markers of resistance to oxaliplatin-based treatment in non-treated tumours. Thereby, oxaliplatin resistance acquisition genes seems not to be involved in intrinsic drug resistance probably due to the fact that acquired and intrinsic oxaliplatin resistance are not related mechanisms. Further studies to typify oxaliplatin intrinsic resistance potential markers are guaranteed.

No significant financial relationships to disclose.

Pharmacogenomic approach for the identification of novel determinants of acquired resistance to oxaliplatin in colorectal cancer

Oxaliplatin is a third-generation platinum agent used in colorectal cancer treatment. Oxaliplatin resistance acquisition is a complex process mainly based on alteration of genes and pathways involved in its mechanism of action. Therefore, our purpose was to perform a gene expression screening in an in vitro model to identify genes that could play a role in oxaliplatin resistance acquisition processes. Four colorectal cancer cell lines and their oxaliplatin-resistant derived sublines were compared. Microarray analysis was done using Human 19K Oligo Array Slides. RNA from cells were hybridized with a commercial RNA reference sample and labeled with both fluorochromes Cy3 and Cy5. Data were analyzed by hierarchical clustering method. Subsequently, quantitative real-time PCR (qRT-PCR) was used to corroborate microarray data, considering as positively validated those genes that showed significant differences in expression levels between groups and a correlation between microarray and qRT-PCR data. By microarray analysis, 32 candidate genes were identified. After validation process by qRT-PCR, the genes AKT1, CDK5, TRIP, GARP, RGS11, and UGCGL1 were positively validated. The 3 first genes proved to be involved in regulation of nuclear factor-kappabeta antiapoptotic transcription factor previously related to drug resistance, and the other 3 genes are novel finds. We have identified 6 genes related to oxaliplatin resistance acquisition. These findings are of paramount importance to understand these processes better and open new lines of study to elucidate the relevance of this pharmacogenomic approach into the clinic.

Pharmacogenetic approach for capecitabine or 5-fluorouracil selection to be combined with oxaliplatin as first-line chemotherapy in advanced colorectal cancer

We studied the role of TS (5'VNTR, 5'SNP and 3'UTR), XRCC1-399, XPD-751, ERCC1-118 and XRCC3-241 genetic polymorphisms in tailoring fluroropyrimidine/oxaliplatin treatment. For this purpose, 110 XELOX (capecitabine/oxaliplatin)- or FUOX (fluorouracil/oxaliplatin)-treated metastatic colorectal cancer patients were selected prospectively for genotyping. In the FUOX group, TS-3'UTR +6bp/+6bp (hazards ratio, HR=2.62, p=0.007) and ERCC1-118C/T or C/C (HR=1.96, p=0.050) genotypes correlated with a shorter progression-free survival (PFS). When analysed jointly, the higher the number of favourable genotypes (FG) the longer the PFS (6.8m, 9.6m and 25.8m for 0, 1 or 2 FG; p=0.005). Disease-control rate was 100% in patients with 2 FG (87% and 38.5% for 1 or 0 FG; p=0.001). In the multivariate analysis, ERCC1-118 (HR=2.12, p=0.0037) and TS-3'UTR (HR=2.68, p=0.006) were strong independent prognostic factors. According to this, patients harbouring TS-3'UTR +6bp/+6bp and ERCC1-118C/T or C/C genotypes may better receive capecitabine instead of 5FU in an oxaliplatin-based first-line treatment.

Combined analysis of genetic polymorphisms in thymidylate synthase, uridine diphosphate glucoronosyltransferase and X-ray cross complementing factor 1 genes as a prognostic factor in advanced colorectal cancer patients treated with 5-fluorouracil plus oxaliplatin or irinotecan

The aim of this study was to investigate the influence of combining thymidylate synthase (TS), X-ray cross complementing factor 1 (XRCC1) and uridine diphosphate glucoronosyltransferase (UGT1A1 *28) polymorphism genotypes in response rate and time to progression (TTP) in metastatic colorectal cancer patients treated with 5-fluorouracil (5-FU) plus irinotecan or oxaliplatin (OXA). PCR, RFLP, allelic discrimination and direct sequencing were performed to elucidate TS, XRCC1 and UGT1A1 *28 genotypes in blood from 71 patients. Patients with a number of favourable genotypes (NFG) > or =1 had a lower progression rate and a better TTP than patients with NFG=0 (log-rank p<0.03). In the OXA + 5-FU group, patients with the TS 5' single nucleotide polymorphism and/or XRCC1 genotypes favourable to treatment had a better TTP (log-rank p=0.02). The TS 5' tandem repeat polymorphism and the NFG were independent prognostic factors in the Cox-based multivariate analysis (p<0.03). These results confirm the influence on patient out-come of these genetic polymorphisms and the possibility of studying them together to predict the outcome in first-line treated colorectal cancer patients.

Gene expression profile related to oxaliplatin resistance in a panel of sensitive human colorectal cancer cell lines with acquired resistance to the drug

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Background: Platinum drugs resistance acquisition is a complex process based in the alteration of genes that belong to several pathways related to drug metabolism. To clarify the multifactoriality of these mechanisms, we analyzed gene expression profile in the four CCR cell lines HT29, LoVo, DLD1 and LS513, and their sublines HTOXAR, LOVOXAR, DLDOXAR y LSOXAR that we induced oxaliplatin resistance in our laboratory. The aim of this work consisted on comparing gene expression profile between resistant cells group (cluster R) and sensitive cells group (cluster S) to determine genes and pathways that could play a role in oxaliplatin resistance acquisition process. Methods: Resistance level determination by MTT assay. Gene expression profile analysis through microarray technology (Human 19K oligo): labeled with Genisphere 3DNA Array350 (Dye Swap), and data analysis using Imagene 4.1, ArrayNorm1.7.2 y Genesis 1.5.0 (ANOVA). Results: According to ANOVA analysis of cluster R versus cluster S, we obtained 32 genes that showed significant changes in expression. 15 of these genes were up regulated and 17 were down regulated. We emphasize genes that belong to pathways previously related to oxaliplatin metabolism (AKT1, TRIP and NLK), family of genes that does not expressed in the same chromosome (KIAA0232 and KIAA0256, SLC39A9 and SLC30A9), and family of genes that had previously related to carcinogenesis processes (KRT19, KRT18 and KRT8). Conclusions: It is possible to develop oxaliplatin resistant CCR cell lines. In our oxaliplatin acquired resistance model, 32 genes showed gene expression changes between groups. These genes belong to signal transduction pathways and cellular integrity mechanisms and they could be a future oxaliplatin resistance prediction profile in colorectal cancer patients.

No significant financial relationships to disclose.

Antiproliferative effects of ZD0473 (AMD473) in combination with 5-Fluorouracil or SN38 in human colorectal cancer cell lines

PURPOSE

ZD0473 (AMD473) [cis-amminedichloro(2-methylpyridine) platinum(II)] is a novel platinum agent of proven activity in vitro against a variety of human tumor-derived cell lines even with intrinsic or acquired resistance to CDDP. The aim of this study is to provide the basis for a rational design of ZD0473-based combination in colon cancer.

EXPERIMENTAL DESIGN

We evaluated the cytotoxic effect of ZD0473 administered alone or in combination with 5-Fluorouracil (5FU) or SN38 in a panel of sensitive and 5FU-resistant colorectal cell lines (HT29/HT29-5FUR and LoVo/LoVo-5FUR). We analyzed four sequential schedules of administration: ZD0473 --> 5FU, 5FU --> ZD0473, ZD0473 --> SN38 and SN38 --> ZD0473. MTT-assay and isobologram analyses were performed to determine the synergism/antagonism.

RESULTS

The pattern of response towards ZD0473, administered as single agent, was similar in all cases and independent of the 5FU-resistance phenotype (IC50 from 48.1 to 76.6 microM) and/or p53 status. No differences in sensitivity to ZD0473 alone or in combination were observed between DNA-mismatch repair-proficient (HT29/HT29-5FUR) and -deficient (LoVo/LoVo-5FUR) cells. ZD0473 administered prior to 5FU leads to synergistic/additive effect in all cell lines, while the 5FU --> ZD047 schedule was only synergistic in HT29 cells. Exposure to ZD0473 prior to SN38 leads to a synergistic/additive schedule in LoVo/LoVo-5FUR cells, while SN38 --> ZD0473 schedule was only synergistic in parental cell lines.

CONCLUSIONS

The combinations of ZD0473 and 5FU or SN38 have shown to be active in sensitive and 5FU-resistant colorectal cell lines when a correct schedule of administration is applied. These results may be further exploited to promote new schedules of administration for advanced colorectal cancer treatment.

Weekly regimen of irinotecan/docetaxel in previously treated non-small cell lung cancer patients and correlation with uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) polymorphism

PURPOSE

Inherited variations in drug metabolizing enzymes may influence drug efficacy. This phase II study assesses the impact of second-line weekly irinotecan (CPT-11)/docetaxel in non-small cell lung cancer (NSCLC) patients, and gauges the uridine diphosphate glucuronosyl transferase (UGT1A1) polymorphism influence in toxicity and antitumor activity.

EXPERIMENTAL DESIGN

Fifty-one patients with NSCLC treated with at least one prior chemotherapy regimen were enrolled. Patients received irinotecan 70 mg/m(2) followed by docetaxel 25 mg/m(2). Both drugs were given on days 1, 8, and 15 every 28 days. UGT1A1 polymorphism were analyzed in blood samples of 47 patients. The UGT1A1 polymorphism are classified according to the number of TA repeats in the promoter region of this gene.

RESULTS

Three patients (6%) achieved a partial response and nineteen patients (37%) had stable disease. Median survival was 8 months (95% CI: 4.8-11.2) and 1-year survival 30%. Grade 3-4 hematologic toxicity was low (less than 10% of patients); 15% of patients had grade 3 asthenia and 25% of patients had grade 3/4 diarrhea. The frequency of UGT1A1 genotypes was as follows: 6/6 49%, 6/7 36%, and 7/7 15%. No differences in toxicity were observed according to UGT1A1 polymorphism. A nonsignificant improvement in time to progression (4 vs. 3 months) and median survival (11 vs. 8 months) was detected in patients with the variant alleles (6/7 and 7/7).

CONCLUSIONS

This weekly irinotecan/docetaxel regimen has shown an acceptable toxicity profile while encouraging median and 1-year survival in heavily pretreated NSCLC patients. The tendency to better prognosis in patients carrying the variant genotypes 6/7 and 7/7 of UGT1A1 gene requires further validation.

Chromosomal imbalance maps of human 5FU-resistant colorectal cancer cell lines: implications in the analysis of 5FU-acquired resistance mechanisms

Thymidylate synthase (TS), a critical enzyme in the de novo synthesis of thymidylate, is an important target for fluoropyrimidines and folate-based TS inhibitors. Overexpression of TS has been correlated to 5-fluorouracil (5FU)-resistance. Because 5FU still remains a basic component of the treatment of colorectal cancer, circumvention of resistance is of vital importance. A panel of sensitive (HT29 and LoVo) and 5FU-resistant colorectal cancer cell lines (HT29-5FUR and LoVo-5FUR) were subjected to comparative genomic hybridization (CGH) analysis to identify possible amplified/deleted regions associated with 5FU-resistance in colon tumours. We have identified chromosomal gains at 5p, 6, 7p, 7q and 8q and one loss at 3q in 5FU-resistant cells as compared to corresponding sensitive cell lines. Neither chromosomal gains at 18p nor gene amplification of TS were observed in our resistant cell lines although an overexpression of TS gene exists (at mRNA level) in these cell lines as compared with corresponding parental cells. Most of the chromosomal gains identified in this study occur frequently in sporadic colorectal tumours and has been associated to a poor prognosis and a greater progression of the tumour and could be related to a worse chemotherapy response. The chromosomal imbalance profile detected in 5FU-resistant cell lines should provide a basis for interpreting mechanisms of 5FU-resistance in colorectal cancer and also possibly in other tumours treated with this agent. This study also identified new genes potentially implicated in 5FU-resistance and suggests new targets that could be useful for the chemotherapy treatment of colorectal cancer.