Thymidylate synthase polymorphisms in genomic DNA as clinical outcome predictors in a European population of advanced non-small cell lung cancer patients receiving pemetrexed

Evaluation of TS and ENOSF1 Variants as a Biomarker in Response to Neoadjuvant Chemotherapy based on 5FU in Gastric Cancer Patients

OBJECTIVE

Neoadjuvant chemotherapy with 5-fluorouracil (5FU) is one of the most effective treatment options for gastric cancer patients.  However, treatment response varies significantly between patients based on their genetic profile. The purpose of this study was to determine the association between thymidylate synthase (TS) and enolase superfamily member 1 (ENOSF1) polymorphisms, treatment response, and overall survival in patients with gastric cancer.

METHODS

The TS and ENOSF1 variants were analyzed in formalin-fixed paraffin-embedded (FFPE) tissue from 100 gastric cancer patients receiving neoadjuvant 5FU-based chemotherapy. Polymerase chain reaction (PCR) amplification and restriction fragment length polymorphism (RFLP) were used to determine TS polymorphisms' genotypes, and the Tetra Arms PCR method was used to identify ENOSF1 polymorphisms. Patients were followed for up to five years, and the association between variants, treatment response, and overall survival (OS) was examined.

RESULTS

There was a significant association between the TS 5' UTR polymorphism and response to treatment in patients with gastric cancer who received neoadjuvant 5FU therapy (P=0.032). Patients with the 2R3R genotype responded better to treatment, whereas those with the 3R3R genotype did not respond to treatment. Patients with the 2R2R and 3R3R genotypes had the longest and shortest median survival times, respectively, and the observed differences were significant (p=0.003). There was a statistically significant relationship between rs2612091 and chemotherapy response (P=0.017). Patients with genotype AG did not respond to treatment.

CONCLUSION

This study established that the TS 5' UTR and ENOSF1 rs2612091 polymorphisms could be used to predict treatment response and overall survival in patients with gastric cancer who received neoadjuvant chemotherapy based on 5FU.

Mechanisms of resistance to chemotherapy in non-small cell lung cancer

Non-small cell lung cancer (NSCLC), which represents 80-85% of lung cancer cases, is one of the leading causes of human death worldwide. The majority of patients undergo an intensive and invasive treatment regimen, which may include radiotherapy, chemotherapy, targeted therapy, immunotherapy, or a combination of these, depending on disease stage and performance status. Despite advances in therapeutic regimens, the 5-year survival of NSCLC is approximately 20-30%, largely due to diagnosis at advanced stages. Conventional chemotherapy is still the standard treatment option for patients with NSCLC, especially those with advanced disease. However, the emergence of resistance to chemotherapeutic agents (chemoresistance) poses a significant obstacle to the management of patients with NSCLC. Therefore, to develop efficacious chemotherapeutic approaches for NSCLC, it is necessary to understand the mechanisms underlying chemoresistance. Several mechanisms are known to mediate chemoresistance. These include altered cellular targets for chemotherapy, decreased cellular drug concentrations, blockade of chemotherapy-induced cell cycle arrest and apoptosis, acquisition of epithelial-mesenchymal transition and cancer stem cell-like phenotypes, deregulated expression of microRNAs, epigenetic modulation, and the interaction with tumor microenvironments. In this review, we summarize the mechanisms underlying chemoresistance and tumor recurrence in NSCLC and discuss potential strategies to avoid or overcome chemoresistance.

Mechanisms of resistance to pemetrexed in non-small cell lung cancer

Currently, lung cancer has remained the most common cause of cancer death while non-small cell lung cancer (NSCLC) accounts for the most of all lung cancer cases. Regardless of multiple existing managements, chemotherapy regimens are still the mainstay of treatment for NSCLC, where pemetrexed has shown cytotoxic activity and has increasingly been used, especially for advanced cases. However, chemo-resistance may inhibit clinical efficacy after long-term use. Mechanisms responsible for chemo-resistance to pemetrexed in NSCLC are plethoric but can be separated into two categories to be discussed: tumor cells and their interactions with drugs. Phenomena relevant to tumor cells such as oncogene or oncoprotein alterations, DNA synthesis, DNA repair, and tumor cell biology behavior are discussed, as well as processes associated with drug dynamics, including drug uptake, drug elimination, and antifolate polyglutamylation. This review will focus on clinical trials and the basic biomedical mechanisms of NSCLC treated with pemetrexed and will describe the underlying mechanisms of resistance to facilitate more efficient clinical therapies to treat patients.

Influence of TS (rs34743033) and RUNX1 (rs2014300) gene polymorphisms on survival outcomes of fluorouracil-based chemotherapy in Chinese advanced gastric cancer patients

Background

This study aimed to explore the clinical correlation of single-nucleotide polymorphisms of thymidylate synthase (TS) and runt-related transcription factor 1 (RUNX1) in patients with postoperative stage II and III gastric cancer (GC).

Patients and methods

Samples were obtained from 661 patients with postoperative stage II and III GC. TS (rs34743033) and RUNX1 (rs2014300) were genotyped in 261 patients who received postoperative basic platinum and fluorouracil chemotherapy regimens and 400 patients who did not accept chemotherapy.

Results

TS (rs34743033) variant genotypes significantly prolonged the median overall survival (OS) time compared to the patients who only received adjuvant chemotherapy (HR 1.604, 95% CI 1.068–2.410, p=0.021). Moreover, 3R/3R variant genotypes were demonstrated to have a positive effect on the OS of patients who received chemotherapy based on cisplatin (HR 1.754, 95% CI 1.041–2.954, p=0.031) compared to oxaliplatin. A stratification analysis indicated that 2R/3R and 2R/2R variant genotypes were associated with inferior survival in GC patients with intestinal-type tumors, tumor less than 5 cm in size, and poorly differentiated tumors (p<0.05). However, RUNX1 (rs2014300) AA genotypes markedly increased the risk of death in GC patients compared with the GG/GA genotypes (p=0.007), but no significant difference was observed between chemotherapy based on platinum. The stratification analysis showed that the GA/AA genotype was significantly associated with inferior survival in well to moderately differentiated tumors (HR 2.001, 95% CI 1.082–3.703, p=0.023).

Conclusion

These preliminary results indicated that the two polymorphisms had a significant effect on postoperative adjuvant chemotherapy. TS (rs34743033) and RUNX1 (rs2014300) may be used as biomarkers to predict prognosis and select chemotherapy regimens in GC patients.

Current Smoking has a Detrimental Effect on Survival for Epidermal Growth Factor Receptor (EGFR) and Anaplastic Lymphoma Kinase (ALK) negative Advanced non-squamous Non-small Cell Lung Cancer (NSCLC) Patients Treated with Pemetrexed Continuation Maintenance

Objectives: The aim of this study is to investigate the predictive value of smoking history on treatment outcomes of pemetrexed continuation maintenance therapy in advanced non-squamous NSCLC patients without EGFR mutations and ALK rearrangements.

Methods: 71 consecutive EGFR and ALK negative advanced non-squamous NSCLC patients who had received pemetrexed continuation maintenance therapy at least two cycles were retrospectively analyzed in our single center. The enrolled patients were categorized into two groups as never-/former light smokers and current smokers according to their smoking history.

Results: In the 71 non-squamous NSCLC patients, 30 (42.3%) were never-/former light smokers and 41 (57.7%) were current smokers. The objective response rate (ORR) of never-/former light smokers was significantly higher than that of current smokers (26.7% vs. 7.3%, p = 0.026). Never-/former light smokers showed significantly longer progression free survival (PFS) (6.6 [95% CI 5.3-7.9] months vs. 5.1 [95% CI 3.5-6.7] months; HR: 0.557, 95% CI 0.339-0.915, p = 0.021) and overall survival (OS) (17.3 [95% CI 14.4-20.2] months vs. 15.7 [95% CI 12.0-19.4] months; HR: 0.578, 95% CI 0.338-0.986, p = 0.044) than current smokers. Multivariate analysis identified smoking history was an independent predictive factor for PFS and OS.

Conclusions: Current smoking is an independent negative predictive factor of outcomes for pemetrexed continuation maintenance therapy in advanced non-squamous NSCLC patients without EGFR mutations and ALK rearrangements.

Pretreatment Red Blood Cell Total Folate Concentration Is Associated With Response to Pemetrexed in Stage IV Nonsquamous Non-Small-cell Lung Cancer

INTRODUCTION

Pemetrexed inhibits folate-dependent enzymes involved in pyrimidine and purine synthesis. Previous studies of genetic variation in these enzymes as predictors of pemetrexed efficacy have yielded inconsistent results. We investigated whether red blood cell (RBC) total folate, a phenotypic rather than genotypic, marker of cellular folate status was associated with the response to pemetrexed-based chemotherapy in advanced nonsquamous non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

We conducted a prospective cohort study of patients with stage IV nonsquamous NSCLC receiving first-line chemotherapy containing pemetrexed. The pretreatment RBC total folate level was quantified using liquid chromatography mass spectrometry. We then compared the objective response rate (ORR) between patients with RBC total folate concentrations greater than and less than an optimal cutoff value determined from the receiver operating characteristic curve. A logistic regression model was used to adjust for age, sex, and the use of bevacizumab.

RESULTS

The ORR was 62% (32 of 52 patients). Receiver operating characteristic analysis was used to establish that a RBC total folate cutoff value of 364.6 nM optimally discriminated between pemetrexed responders and nonresponders. Patients with RBC total folate < 364.5 nM had an ORR of 27% compared with 71% for patients with RBC total folate > 364.5 nM (P = .01). This difference persisted after adjusting for age, sex, and the use of bevacizumab (odds ratio, 0.07; 95% confidence interval, 0.01-0.57; P = .01).

CONCLUSION

A low pretreatment RBC total folate was associated with an inferior response to pemetrexed-based chemotherapy in stage IV nonsquamous NSCLC. Larger, multicenter studies are needed to validate RBC total folate as a predictive marker of pemetrexed response.

Maintenance therapy with pemetrexed and bevacizumab versus pemetrexed monotherapy after induction therapy with carboplatin, pemetrexed, and bevacizumab in patients with advanced non-squamous non small cell lung cancer

OBJECTIVES

Single agent maintenance therapy is widely accepted for advanced non-squamous non small cell lung cancer (NSCLC). However, there is no consensus on the initial and maintenance phase regimens, and the clinical benefit of adding bevacizumab to cytotoxic drugs in the maintenance phase remains unclear.

METHODS

Chemotherapy-naïve patients with non-squamous NSCLC were randomly assigned to maintenance therapy with pemetrexed and bevacizumab or pemetrexed alone, after achieving disease control after four cycles of induction therapy with carboplatin (area under the curve = 6), pemetrexed (500 mg/m(2)), and bevacizumab (15 mg/kg). The primary end-point was 1-year progression-free survival (PFS) rate.

RESULTS

One hundred ten patients were enrolled in the study, with 55 patients assigned to the two groups. The mean 1-year PFS rate was 43.9% (95% confidence interval [CI]: 29.6-59.2%) in the combination maintenance group and 35.2% (95% CI: 22.1-51.0%) in the pemetrexed maintenance group, and the difference was not significant (p = 0.433). Median PFS measured from enrolment was 11.5 months (95% CI: 7.1-19.0) in the combination maintenance group and 7.3 months (95% CI: 5.7-14.1, hazard ratio: 0.73, 95% CI: 0.44-1.19, log-rank p = 0.198) in the pemetrexed maintenance group. Nasal haemorrhage, hypertension, and proteinuria were significantly more frequent in the combination maintenance group, but they were mild and tolerable.

CONCLUSION

Both maintenance therapy with pemetrexed alone and pemetrexed and bevacizumab in combination were feasible in patients with non-squamous NSCLC who have achieved disease control after induction therapy with carboplatin, pemetrexed, and bevacizumab. According to the selection design, differences in the superiority between these maintenance therapies were not demonstrated.

Polymorphisms in TS, MTHFR and ERCC1 genes as predictive markers in first-line platinum and pemetrexed therapy in NSCLC patients

Purpose

We presented retrospective analysis of up to five polymorphisms in TS, MTHFR and ERCC1 genes as molecular predictive markers for homogeneous Caucasian, non-squamous NSCLC patients treated with pemetrexed and platinum front-line chemotherapy.

Methods

The following polymorphisms in DNA isolated from 115 patients were analyzed: various number of 28-bp tandem repeats in 5′-UTR region of TS gene, single nucleotide polymorphism (SNP) within the second tandem repeat of TS gene (G>C); 6-bp deletion in 3′-UTR region of the TS (1494del6); 677C>T SNP in MTHFR; 19007C>T SNP in ERCC1. Molecular examinations’ results were correlated with disease control rate, progression-free survival (PFS) and overall survival.

Results

Polymorphic tandem repeat sequence (2R, 3R) in the enhancer region of TS gene and G>C SNP within the second repeat of 3R allele seem to be important for the effectiveness of platinum and pemetrexed in first-line chemotherapy. The insignificant shortening of PFS in 3R/3R homozygotes as compared to 2R/2R and 2R/3R genotypes were observed, while it was significantly shorter in patients carrying synchronous 3R allele and G nucleotide. The combined analysis of TS VNTR and MTHFR 677C>T SNP revealed shortening of PFS in synchronous carriers of 3R allele in TS and two C alleles in MTHFR. The strongest factors increased the risk of progression were poor PS, weight loss, anemia and synchronous presence of 3R allele and G nucleotide in the second repeat of 3R allele in TS. Moreover, lack of application of second-line chemotherapy, weight loss and poor performance status and above-mentioned genotype of TS gene increased risk of early mortality.

Conclusion

The examined polymorphisms should be accounted as molecular predictor factors for pemetrexed- and platinum-based front-line chemotherapy in non-squamous NSCLC patients.