Molecular markers of chemotherapeutic response and toxicity in colorectal cancer

Pharmacogenetic analyses of 2183 patients with advanced colorectal cancer; potential role for common dihydropyrimidine dehydrogenase variants in toxicity to chemotherapy

BACKGROUND

Inherited genetic variants may influence response to, and side-effects from, chemotherapy. We sought to generate a comprehensive inherited pharmacogenetic profile for oxaliplatin and 5FU/capecitabine therapy in advanced colorectal cancer (aCRC).

METHODS

We analysed more than 200 potentially functional, common, inherited variants in genes within the 5FU, capecitabine, oxaliplatin and DNA repair pathways, together with four rare dihydropyrimidine dehydrogenase (DPYD) variants, in 2183 aCRC patients treated with oxaliplatin-fluoropyrimidine chemotherapy with, or without, cetuximab (from MRC COIN and COIN-B trials). Primary end-points were response, any toxicity and peripheral neuropathy. We had >85% power to detect odds ratios (ORs) = 1.3 for variants with minor allele frequencies >20%.

RESULTS

Variants in DNA repair genes (Asn279Ser in EXO1 and Arg399Gln in XRCC1) were most associated with response (OR 1.9, 95% confidence interval [CI] 1.2-2.9, P = 0.004, and OR 0.7, 95% CI 0.5-0.9, P = 0.003, respectively). Common variants in DPYD (Cys29Arg and Val732Ile) were most associated with toxicity (OR 0.8, 95% CI 0.7-1.0, P = 0.008, and OR 1.6, 95% CI 1.1-2.1, P = 0.006, respectively). Two rare DPYD variants were associated with increased toxicity (Asp949Val with neutropenia, nausea and vomiting, diarrhoea and infection; IVS14+1G>A with lethargy, diarrhoea, stomatitis, hand-foot syndrome and infection; all ORs > 3). Asp317His in DCLRE1A was most associated with peripheral neuropathy (OR 1.3, 95% CI 1.1-1.6, P = 0.003). No common variant associations remained significant after Bonferroni correction.

CONCLUSIONS

DNA repair genes may play a significant role in the pharmacogenetics of aCRC. Our data suggest that both common and rare DPYD variants may be associated with toxicity to fluoropyrimidine-based chemotherapy.

The abridged patient-generated subjective global assessment is a useful tool for early detection and characterization of cancer cachexia

Cancer cachexia (CC) is a syndrome characterized by wasting of lean body mass and fat, often driven by decreased food intake, hypermetabolism, and inflammation resulting in decreased lifespan and quality of life. Classification of cancer cachexia has improved, but few clinically relevant diagnostic tools exist for its early identification and characterization. The abridged Patient-Generated Subjective Global Assessment (aPG-SGA) is a modification of the original Patient-Generated Subjective Global Assessment, and consists of a four-part questionnaire that scores patients' weight history, food intake, appetite, and performance status. The purpose of this study was to determine whether the aPG-SGA is associated with both features and clinical sequelae of cancer cachexia. In this prospective cohort study, 207 advanced lung and gastrointestinal cancer patients completed the following tests: aPG-SGA, Edmonton Symptom Assessment System, handgrip strength, a complete blood count, albumin, apolipoprotein A and B, and C-reactive protein. Ninety-four participants with good performance status as assessed by the Eastern Cooperative Oncology Group Performance Status completed additional questionnaires and underwent body composition testing. Of these, 68 patients tested for quadriceps strength and completed a 3-day food recall. Multivariable regression models revealed that higher aPG-SGA scores (≥9 vs 0 to 1) are significantly associated (P<0.05) with the following: unfavorable biological markers of cancer cachexia, such as higher white blood cell counts (10.0 vs 6.7×10(9)/L; lower hemoglobin (115.6 vs 127.7 g/L), elevated C-reactive protein (42.7 vs 18.2 mg/L [406.7 vs 173.3 nmol/L]); decreased anthropometric and physical measures, such as body mass index (22.5 vs 27.1); fat mass (14.4 vs 26.0 kg), handgrip (24.7 vs 34.9 kg) and leg strength; an average 12% greater length of hospital stay; a dose reduction in chemotherapy; and increased mortality. Given its association with the main features of cancer cachexia and its ease of use, the aPG-SGA appears to be a useful tool for detecting and predicting outcomes of cancer cachexia. Additional research is required to determine what impact the aPG-SGA has on quality of care when used in the clinical setting.

Novel chemosensitive single-nucleotide polymorphism markers to targeted regimens in metastatic colorectal cancer

PURPOSE

Methods for predicting individual responsiveness to targeted chemotherapy are urgently needed, considering the frequent resistance and extremely high cost.

EXPERIMENTAL DESIGN

A chemosensitive single-nucleotide polymorphism (SNP) discovery schema is presented that utilizes (i) genome-wide SNP screening with a human SNP array and an in vitro chemosensitivity assay in 118 colorectal cancers, (ii) clinical association analysis in the other 98 patients who had received chemotherapy for metastatic cancer, and (iii) biological utility assessment using cell viability assays of transfected colorectal cancer (CRC) cells.

RESULTS

Nine SNPs related to bevacizumab and cetuximab regimen sensitivity were chosen during screening. Overall responses for bevacizumab regimens revealed that patients carrying the TT genotype at ANXA11 rs1049550 or at least one G allele at LINS1 rs11247226 seemed greater chemosensitive than those carrying at least one C allele or the AA genotype, respectively (P < 0.05). For cetuximab regimens, patients carrying the GG genotype at DFNB31 rs2274159 or LIFR rs3729740 seemed greater chemosensitive than those carrying at least one A allele (P = 0.025 and P = 0.07). Cytotoxicity analyses showed that all RKO and HCT116 CRC clones transfected with the G allele at LIFR rs3729740 and the C allele at ISX rs361863 were more sensitive to cetuximab regimens than those with the A and T allele, respectively (P ≤ 0.001-0.024).

CONCLUSIONS

Chemosensitive SNP markers were identified using a novel three-step process. The candidate marker LIFR rs3729740 and possibly ISX rs361863 will hopefully predict responsive patients to cetuximab regimens, although further validation is needed in large cohorts.

Genome-wide identification of chemosensitive single nucleotide polymorphism markers in colorectal cancers

Improved methods for predicting chemoresponsiveness involving the identification of polymorphic markers is highly desirable, considering narrow therapeutic index and frequent resistance to anti-cancer regimens. The genome-wide screening of chemosensitive single nucleotide polymorphisms (SNPs) was undertaken in association with in vitro chemosensitivity assays in 104 colorectal cancer patients for the initial screening step. Allele frequency, linkage disequilibrium, potential function, and Hardy-Weinberg equilibrium of the candidate SNPs were then determined for the identifying step. Finally, clinical association analysis in the other 260 evaluable patients or cell viability assays of transfected RKO cells was used to verify candidate SNPs for the validation step. In total, 12 SNPs to six regimens were initially chosen during the screening and identifying steps. In patients receiving fluoropyrimidine-based adjuvant chemotherapy, the substitution alleles of GPC5 rs553717 (AA) correlated significantly with tumor recurrence and shorter disease-free survival (P = 0.019 and 0.023, respectively). Interestingly, RKO cells expressing mutant GPC5 showed enhanced cell death in response to 5-FU in cytotoxicity assays. Patients that were homozygous for the reference alleles SSTR4 rs2567608 (AA) and EPHA7 rs2278107 (TT) showed lower disease control rates in response to irinotecan and oxaliplatin regimens, respectively, than those with substitution alleles (P = 0.022 and 0.014, respectively). Thus, we identified chemosensitive SNP markers using a novel three step process of genome-wide analysis consisting of in vitro screening, identification, and validation. The candidate chemosensitive SNP markers identified in our study, including those identified in vitro, can now be further verified in a large cohort study.

Irinotecan as palliative chemotherapy for metastatic colorectal cancer: evolving tactics following initial treatment

BACKGROUND

Patients with metastatic colorectal cancer (mCRC) who progress despite treatment with fluoropyrimidine and irinotecan or oxaliplatin have diminished survival, but they may derive clinically meaningful benefit from second-line or later chemotherapy.

MATERIALS AND METHODS

Literature from 2000 through mid-2008 on the treatment of patients with unresectable mCRC was reviewed to identify options for chemotherapy-resistant patients with mCRC.

RESULTS AND CONCLUSIONS

A recurring finding is that overall survival increases when patients are exposed to all available active agents throughout their course of care, independent of the line of treatment in which medication is delivered. Sequential administration of agents, including irinotecan, oxaliplatin, bevacizumab, and cetuximab, or, alternatively, deferred administration of various medications in combination, have shown promising efficacy that is at least equivalent to established combination regimens with the same agents. Palliative chemotherapy clearly improves survival in patients with unresectable mCRC, with overall survival recently reaching 28 months.

Evaluation of novel histone deacetylase inhibitors as therapeutic agents for colorectal adenocarcinomas compared to established regimens with the histoculture drug response assay

BACKGROUND AND AIMS

This study was to evaluate the efficacy of histone deacetylase (HDAC) inhibitors in colorectal cancer together with other established regimens.

MATERIALS AND METHODS

Chemosensitivities of 114 colorectal cancer patients to established regimens (fluorouracil (5-FU with leucovorin (FL), capecitabine, FL with irinotecan (FLIRI), and FL with oxaliplatin (FLOX)) as well as five hydroxamic acid derivatives (suberoylanilide hydroxamic acid, PXD101, and three novel candidates of CG-1, CG-2, and CG-3) were comparatively evaluated using the histoculture drug response assay.

RESULTS

The chemosensitivity with established regimens was between 34.2% and 52.6%, when the cutoff value of the inhibition ratio was set at 30%, and between 54.5% and 84.1% with HDAC inhibitors. All HDAC inhibitors displayed synergistic effects in combination with established regimens of FLOX and FLIRI (P < or = 0.0001-0.002). Advanced T- and N-category tumors and patients with synchronous adenoma displayed higher chemosensitivity to CG-3, CG-2, and CG-1, respectively, on a multivariate analysis (P = 0.023, 0.044, and 0.045, respectively). Tumors with mismatch repair defects were closely correlated with chemosensitivities to combined regimens of PDX101 with FLOX and FLIRI (P = 0.044 and 0.048, respectively).

CONCLUSIONS

Our findings firstly demonstrated the chemo-responsiveness of colorectal cancers to HDAC inhibitors with therapeutic efficacy comparable to the established regimens. Additionally, tumor growth and heredity were significantly associated with specific regimens, supporting their possible role as chemosensitive predictors.

Predictive molecular markers for colorectal cancer patients with resected liver metastasis and adjuvant chemotherapy

BACKGROUND & AIMS

The aims of the study were to evaluate the predictive value of 8 candidate molecular markers for colorectal cancer (CRC) patients receiving hepatic arterial infusion (floxuridine [FUDR] and dexamethasone) and systemic irinotecan (CPT11) post resection of liver metastasis.

METHODS

RNA was extracted from microdissected tumor cells of fixed and embedded specimens of resected liver metastases (94 cases) and analyzed by quantitative reverse-transcription polymerase chain reaction (RT-PCR) for thymidine phosphorylase, dihydropyrimidine dehydrogenase, thymidylate synthase, uridine phosphorylase, uridine/cytidine (monophospho)kinase, Bcl-2 related protein, Cyclin-D1, and Survivin expression. Uni- and multivariate statistical analyses and an explorative hierarchical clustering analysis of quantitative RT-PCR data were performed for overall survival and recurrent disease.

RESULTS

After adjustment for multiple clinicopathologic parameters, none of the markers were significantly associated with overall survival (except, marginally, Cyclin-D1; P = .06) or extrahepatic recurrence. However, high Survivin (P = .03) and Cyclin-D1 (P = .05) levels were predictive for hepatic recurrence. Hierarchical cluster analysis identified 7 of 94 patients associated with lower hepatic recurrence (P < .001). This patient group was characterized by low Cyclin-D1 and Survivin messenger RNA levels, both genes also clustering together.

CONCLUSIONS

Cyclin-D1 and Survivin messenger RNA analyzed by standardized, quantitative RT-PCR are predictive markers for CRC patients receiving hepatic arterial infusion (FUDR/dexamethasone) and systemic CPT11 post resection of liver metastasis. Moreover, our exploratory hierarchical cluster analysis of quantitative RT-PCR data supports its potential as an application to define clinically relevant patient subgroups.