Low Thymidylate Synthase Expression Research Articles

The Predictive Value of ERCC1, RRM1, and Thymidylate Synthase in Advanced Malignant Pleural Mesothelioma Patients Treated with Platinum-Based Chemotherapy.

A rare yet severe neoplasia called malignant pleural mesothelioma (MPM) typically manifests itself in advanced stages. Despite some improvements in the treatment of patients with MPM, this malignancy continues to have a detrimental prognosis . The primary goal of the present study was to assess the associatin between ERCC1, RRM1, and thymidylate synthase (TS) expression and disease outcome in patients with malignant pleural mesothelioma (MPM) treated with either pemetrexed plus cisplatin or gemcitabine plus cisplatin. This prospective cohort study was done on ninety-one advanced MPM patients. The patients received either pemetrexed plus platinum (55 of 91) or gemcitabine plus platinum chemotherapy (36 of 91). Tissue biopsy was taken at time of diagnosis. Immunohistochemistry was used to assess the levels of ERCC1, RRM1, and TS transcription in tissue biopsies (paraffin embedded). Based on the findings, 70% of patients with low expression of TS had low expression of ERCC1, and 68% of patients with high expression of TS had high expression of ERCC1, suggesting a significat association between ERCC1 expression and TS expression (p=0.005). However, there was no relation between ERCC1 and RRM1 expression patterns (p= 0.296). In patients underwen platinum-based theraphy (n 91), a significant correlation was detected between low ERCC1 median High-scoring and longer progression time (TTP;9.6 v 5.3 months;P< .001) or overall survival (OS) (OS;18.1 v 9.1 months; P<0.001). A significant correlation was found between low TS protein expression and longer time progression (TTP; 11.8 v 5.4 months; P< .001) or OS (OS; 19.8 v 8.5 months; P <0.001) in patients undergoing pemetrexed plus platinum chemotherapy (n 55). Low RRM1 expression was accompanied by high progression free survival (TTP; 10.6 v 3.8 months) and OS (OS; 20.6 v 8.6 months) in patients receiving gemcitabine plus platinum chemotherapy. Based on the multivariate test results, the independent variables significantly affecting OS were tumor stage (HR: 2.3; 95% CI: 1.1-4.9; p= 0.021) and ERCC1 (HR: 2.7; 95% CI: 1.7-4.3; p < 0.001). Decreased TS protein expression can be indicative of greater responsivness to pemtrexed and of longer TTP and OS in individuals with advanced MPM (locally progressed or metastatic) who are receiving pemetrexed-based chemotheraphy. Low ERCC1 expressions in individuals with advanced MPM can predict increased PFS and OS, as well as a better responsivness to platinum-based chemotherapy. In patients with progressed MPM receiving gemcitabine plus cisplatin chemotherapy, lower RRM1 expression was associated with a better prognosis, longer PFS, and longer OS.

Expression of astrocyte-elevated gene-1 indicates prognostic value of fluoropyrimidine-based adjuvant chemotherapy in resectable stage III colorectal cancer.

It is unclear which prognostic factor such as pathological features and gene mutation are majorly relevant for stage III disease and whether they aid in determining patients who will be benefit from postoperative adjuvant chemotherapy. The expression of astrocyte-elevated gene-1 (AEG-1), thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) was examined to investigate their role in adjuvant chemotherapy for patients with resectable stage III colorectal cancer (CRC). A significant positive correlation was observed between AEG-1, TS, ERCC1, EGFR, and VEGF gene expression levels in CRC cell lines, and low AEG-1 and TS expression were highly sensitive to 5-fluorouracil treatment. Our results showed that AEG-1 expression was high in T4 and caused CRC recurrence or metastasis. Patients with T4, high AEG-1, TS and VEGF expression had a significantly short disease-free survival and overall survival. In multivariate Cox regression analysis, high AEG-1 expression could be an independent prognostic factor indicating poor survival in patients with resectable stage III CRC treated with adjuvant chemotherapy. In conclusion, AEG-1 expression and tumor grade are potential prognostic factors for recurrence and survival in patients with stage III CRC receiving adjuvant fluoropyrimidine-based chemotherapy.

Pemetrexed plus cisplatin in patients with previously treated advanced sarcoma: a multicenter, single-arm, phase II trial

BackgroundPatients with advanced sarcomas have a poor prognosis and few treatment options that improve overall survival. We assessed the efficacy and tolerability of pemetrexed and cisplatin combination therapy in patients with refractory bone and soft tissue sarcoma (STS).Patients and MethodsPatients were included in this multicenter, phase II study (ClinicalTrials.gov identifier NCT03809637) if they progressed after receiving one or more chemotherapy regimens containing an anthracycline and/or ifosfamide. Pemetrexed was first administered intravenously, followed by cisplatin, over a cycle of 21 days, for a maximum of six cycles. The primary endpoint was a progression-free rate (PFR) at 3 months (3-month PFR).ResultsFrom January 2017 to September 2019, we enrolled 37 patients; of these, 73% had previously undergone three or more rounds of chemotherapy. Five patients (13.5%) exhibited objective responses, including two patients (2/6, 33.3%) with malignant peripheral nerve sheath tumors, one patient (1/4, 25%) with synovial sarcoma, one patient (1/4, 25%) with undifferentiated pleomorphic sarcoma, and one patient (1/4, 25%) with angiosarcoma. The median progression-free survival was 2.6 months, and the 3-month PFR was 45.9% (n = 17). None of the four patients with osteosarcoma exhibited objective responses or were progression free at 3 months. The most frequent treatment-related grade 3-4 toxicities included neutropenia (16.2%), anemia (13.5%), thrombocytopenia (13.5%), and fatigue (8.1%). Among 26 patients (70.3%) available for immunohistochemical assessments, patients in the low-excision repair cross-complementation group 1 (ERCC1) and low-thymidylate synthase expression groups showed a tendency for longer overall survival.ConclusionsCombination therapy with pemetrexed and cisplatin was associated with clinically meaningful and sustained responses among patients with advanced and refractory STS. The combination therapy met its predefined primary study endpoint.

EP1.01-71 Thymidylate Synthase and Folate Receptor Alpha Expression as Potential Biomarkers for Efficacy of Pemetrexed in NSCLC

Predictive biomarkers for chemotherapy in advanced non-squamous NSCLC are lacking. Thymidylate synthase (TS) and folate receptor alpha (FRA) are target enzymes for pemetrexed. Here we investigated TS and FRA expression and their role as a prognostic and predictive biomarker for efficacy of pemetrexed-based chemotherapy. We performed immunohistochemistry on pre-treatment tumour specimens for TS and FRA expression and correlated it with patient’s demographic and clinical characteristics, treatment responses and survivals in a retrospective training cohort of patients with advanced non-squamous NSCLC treated with pemetrexed-based chemotherapy. Similar analysis for validation was performed in a prospective cohort of patients participating in a randomized control trial “to compare efficacy and safety of pemetrexed-carboplatin versus paclitaxel-carboplatin as induction regimen in advanced non-squamous NSCLC”. Chi-square test was used to co-relate TS and FRA expression with clinico-pathological characteristics. Kaplan-Meier methods, Log-rank test and Cox proportional-hazards model were used for survival analysis. In the retrospective training cohort median age was 57 (26-70) years with male predominance (ratio=2:1). TS and FRA expression were evaluable in 55 and 47 patients respectively. In this cohort TS and FRA expression didn’t co-relate with best overall response rates (ORR), however, low TS expression and positive FRA expression were associated with improved progression free survival (PFS), albeit non-significant. In the prospective validation cohort median age was 52 (28-65) years with 70% males. In this cohort TS and FRA expression were analysed in 113 and 97 patients respectively. High TS expression was significantly associated with better ORR in patients treated with paclitaxel-carboplatin (p=0.04) but there was no co-relation of TS expression with response rates in pemetrexed-carboplatin group. Younger patients (age<40 years) had more TS ‘low or negative’ status (p=0.04). High TS expression was associated with ALK positivity (p=0.02), bone metastases (p=0.01) and brain metastases (p=0.002). Positive FRA expression was associated with EGFR positivity (p=0.004) and liver metastases (p=0.020). Positive FRA expression was associated with improved PFS in patients treated with pemetrexed-carboplatin (median: 9.23 versus 4.27 months, p=0.01), paclitaxel-carboplatin (median: 10.87 versus 6.47 months, p=0.08) as well as improved OS (median: OS not reached versus 10.13 months, p=0.01), especially in patients treated with pemetrexed-carboplatin (median: 18.73 versus 10.46 months, p=0.08). In conclusion, the results from this study suggest that TS or FRA expression doesn’t predict efficacy of Pemetrexed, however, high TS expression may predict better ORR in patients receiving paclitaxel-carboplatin. FRA expression may serve as a prognostic factor in patients receiving chemotherapy irrespective of the regimen.

High thymidylate synthase gene expression predicts poor outcome after resection of hepatocellular carcinoma.

IntroductionPrognosis after resection of hepatocellular carcinoma (HCC) is highly variable. Compared to clinicopathologic factors, the use of molecular markers to predict outcome has not been well studied. We investigated the prognostic importance of thymidylate synthase (TS) gene expression and polymorphisms in patients after resection of HCC.MethodsPatients who underwent complete resection of HCC for whom tissue was available were identified. TS gene expression level and polymorphisms were determined in HCC specimens. Prognostic factors were evaluated using Kaplan-Meier curves and Cox proportional hazard models.ResultsThe study included 67 patients. In univariate analysis, variables that negatively influenced survival included TNM stage, microvascular invasion, and high TS expression. For the high TS expression group, median survival was 54 months and 5-year actuarial survival was 47%. For the low TS expression group, median survival was not reached and the 5-year actuarial survival was 91%. In multivariate analysis, only high TS expression remained an independent predictor of poor survival (HR = 10.77, 95% CI 1.36–84.91; P = 0.02). TS gene polymorphisms were not associated with TS expression or overall survival.ConclusionsHigh TS expression predicts poor outcome after resection of HCC. Molecular markers might be robust predictors of patient outcome after resection of HCC.

Predictive factors for long-term responders of pemetrexed maintenance treatment in non-small cell lung cancer.

BackgroundWe determined the clinical characteristics and predictive factors of long‐term response to pemetrexed maintenance therapy as first‐line treatment for non‐small cell lung cancer (NSCLC).MethodsA total of 950 advanced NSCLC patients received pemetrexed (500 mg/m2) plus cisplatin (60 mg/m2) (Pem‐Cis) induction chemotherapy every three weeks as first‐line treatment between January 2010 and August 2018. Patients who did not show progression after four cycles of Pem‐Cis and received at least one cycle of pemetrexed maintenance were recruited (n = 199).ResultsPatients were divided into subgroups according to total cycles of pemetrexed: ≤ 10 (F10, n = 134) and > 10 (M10, n = 65). The M10 group had a higher proportion of patients with stage M1a (intrathoracic metastasis alone) and exhibited lower levels of thymidylate synthase (TS) than the F10 group (median H‐score 10.0% vs. 60.0%; P = 0.031). Further subgrouping identified extreme responders: ≤ 7 (F7, n = 101) and ≥ 20 (M20, n = 26) cycles. The M20 group showed lower mean serum CEA levels before (17.5 vs. 147.0; P = 0.099) and after (6.9 vs. 53.2; P = 0.001) Pem‐Cis treatment, and a higher incidence of normalization after Pem‐Cis (abnormal 41.7% vs. 68.5%; P = 0.015). M1a stage, normalization of CEA levels after Pem‐Cis, and lower TS H‐score were predictors of progression‐free survival in patients administered pemetrexed maintenance.ConclusionM1a stage and lower TS expression were predictors of long‐term response to pemetrexed maintenance. CEA normalization after Pem‐Cis could be an additional surrogate marker of positive response to long‐term treatment.

Study on the correlation between thymidylate synthase expression level and postoperative chemotherapy in gastric cancer

Objective To investigate the expression of thymidylate synthase (TS), and the correlations with the clinicopathologcal factors and the prognosis of postoperative fluorouracil chemo-therapy in gastric cancer. Methods 42 patients with gastric cancer who underwent radical gastrectomy were collected from April 2011 to April 2014 in Lu′an Hospital of Anhui Medical University, and the chemotherapy regimen was Cisplatin+ Capecitabine or Cisplatin+ Teggio. The levels of TS in tumor tissues of 42 patients with gastric cancer were detected by immunohistochemical method. The relationships between TS expression level, clinical features and the prognosis of patients treated with fluorouracil chemotherapy were analyzed. Results In 42 patients with gastric cancer, 19 patients (45.2%) have TS high expressions, 23 patients (54.8%) have TS low expressions. There were no significant correlations between the expression of TS and age, sex, clinical stage, differentiation degree, tumor location, depth of invasion, lymph node metastasis, vascular tumor thrombus and nerve bundle invasion (all P>0.05). There were significant differences between low TS expression and high TS expression in median progression-free survival and 3-year survival rate of patients [35 months vs. 17 months, 73.9% (17/23) vs. 42.1% (8/19)], and the differences were statistically significant (χ2=4.788, P=0.029; χ2=4.369, P=0.037). In patients with stage Ⅲ gastric cancer, the median progression-free survival of patients with low TS expression was significantly prolonged compared to that with high TS expression (33 months vs. 9 months), and the difference was statistically significant (χ2=4.731, P=0.030). Conclusion TS expression levels have no significant correlations with the clinicopatho-logcal factors, but closely relate to the prognosis of gastric cancer patients treatment with fluorouracil chemotherapy. The chemotherapy prognosis of TS high expression is worse than that of TS low expression in gastric cancer. Key words: Thymidylate synthase; Stomach neoplasms; Chemotherapy, adjuvant; Fluorouracil

Expression of thymidylate synthase predicts clinical outcomes of S-1-based chemotherapy in squamous cell lung cancer.

Non-small cell lung cancer (NSCLC) patients with squamous cell carcinoma (SCC) histology have limited chemotherapeutic options. Treatment with S-1 combined with carboplatin (CBDCA) has been shown to provide a significant survival benefit in SCC patients compared with treatment with combined CBDCA and paclitaxel. The aim of the present study was to investigate the association between the expression of molecular markers related to the pharmacological action of S-1, including thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT) and dihydropyrimidine dehydrogenase (DPD), and the clinical efficacy of S-1-based chemotherapy in SCC patients. The immunohistochemical expression of TS, OPRT and DPD were retrospectively analyzed in tumor biopsy and resection specimens from patients with advanced SCC (n=32). Immunohistochemical H-scores were calculated and their association with S-1/CBDCA response was evaluated. Median progression-free survival time was significantly longer in patients with low TS H-scores than in those with high TS H-scores (162.5 vs. 97 days; P=0.004); by contrast, overall survival time was not observed to differ significantly between these groups (P=0.185). In the multivariate analysis, low TS expression was a significant positive factor for progression-free survival rate (hazard ratio, 0.40; P=0.021). A low TS H-score was also associated with an increased response to S-1-based chemotherapy compared with a high TS H-score (P=0.002). This indicates that SCC patients with low TS expression can benefit significantly from S-1-based chemotherapy, and that H-score measurement of intratumoral TS expression may represent a useful predictive biomarker for response to S-1-based chemotherapy by patients with SCC-type NSCLC.

A study of thymidylate synthase gene expression as a biomarker for the treatment of esophageal adenocarcinoma.

e15563 Background: Expression of thymidylate synthase (TS), a target of fluoropyrimidine-based (5-FU) chemotherapy, has prognostic value in colorectal adenocarcinoma. Its value as a biomarker in treatment of esophageal adenocarcinoma (EAC) is unknown. With widespread adoption of CROSS trial protocol for treatment of EAC, 5-FU is frequently omitted from regimens. We retrospectively analyzed the association between TS protein expression and clinical outcomes in EAC. Methods: TS expression levels were measured by immunohistochemistry in formalin-fixed paraffin-embedded specimens from 35 primary EAC patients from 2 institutions (range 5/2006-1/2016); at time of diagnosis and surgical resection (33 neoadjuvant chemoradiation and 2 surgery alone). TS expression higher than 1+, 5% was read as positive. Mean follow up was 1323 days (range 263-3677). TS expression correlated with treatment response and survival in patients treated with and without 5-FU therapy (log-rank test, Kaplan-Meier method). Results: In the cohort of 35 patients, 21 patients (60%) had pretreatment positive TS expression. Overall survival (OS) for TS negative patients was 1216 days versus 974 days for TS positive (p = 0.15). In the 23 patients treated with 5-FU, TS-negative patients had a trend towards longer overall survival compared to TS-positive patients, mean OS (1272 days versus 743 days, p = 0.08). In the group of 12 patients not treated with 5-FU, 2 patients showed negative TS staining. Neoadjuvant chemoradiation was performed in 33/35 patients. Downstaging was observed in 69% (9/13) of patients with negative pre-treatment TS levels versus 55% (11/20) in pre-treatment TS positive patients (p = 0.48). In 23 patients treated with 5FU, 9/12 (75%) were downstaged in the TS-negative cohort versus 6/11 (45%) in the TS-positive cohort (p = 0.21). In the 5FU treatment group, complete response was seen in 2 patients with negative TS staining. Conclusions: Low TS expression in EAC patients trended towards improved survival and tumor downstaging, particularly in patients treated with neoadjuvant 5-FU and platinum based therapy. Prospective data and greater patient numbers may be necessary to demonstrate statistical significance.

Вплив інтратуморальної експресії тимідилатсинтази на виживаність хворих на рак підшлункової залози, які отримували гемци­табін і тегафур в ад’ювантному лікуванні

Рак підшлункової залози (РПЖ) входить в першу четвірку в структурі онкологічної смертності. Комбінації фторпіримідинів і гемцитабина давно і активно використовуються в паліативної хіміотерапії РПЖ. У ад'ювантном режимі такі комбінації використовуються рідше, було показано, що вони можуть впливати на довгострокову виживаність, але ефект значно відрізняється серед пацієнтів з різним фенотипом пухлини. Метою нашого дослідження було вивчення взамосвязі рівня експресії тіміділатсінтази (TS) у хворих РПЖ, які отримують ад'ювантному гемцитабін + тегафур (ГемТег), і їх загальної виживаності. У дослідження були залучені 62 пацієнта, яким була виконана радикальна резекція з приводу РПЖ. Aд'ювантная хіміотерапія за схемою ГемТег починалася не раніше 2 тижнів після операції. У всіх випадках протоковая аденокарцинома підшлункової залози була верифікована при рутинному гістологічному дослідженні, після чого імуногістохімічно визначали експресію TS. Дані загального виживання були проаналізовані шляхом побудови кривих Каплана-Майера. Виживання в групах порівнювали за допомогою log-rank тесту. Медіана виживання хворих з високою експресією TS на 14 місяців більше, ніж у хворих з низькою експресією TS (36 і 12 соотв.). Перевага в виживання хворих з високою експресією TS є статистично значущим (р = 0,005). Високий рівень імуногістохімічної експресії TS в пухлинах хворих РПЖ може позитивно впливати на прогноз хворих, які отримують поліхіміотерапію за схемою ГемТег в ад'ювантному режимі.

Evaluating the Prognostic Value of ERCC1 and Thymidylate Synthase Expression and the Epidermal Growth Factor Receptor Mutation Status in Adenocarcinoma Non-Small-Cell Lung Cancer.

The present study evaluated the prognostic value of the epidermal growth factor receptor (EGFR) mutation status, and excision repair cross-complementation group 1 (ERCC1) and thymidylate synthase (TS) expression following intercalated tyrosine kinase inhibitor (TKI) therapy and platinum- and pemetrexed-based chemotherapies (subsequent second-line treatment) for patients with adenocarcinoma non-small-cell lung cancer (AC-NSCLC). In total, 131 patients with AC-NSCLC were enrolled. The EGFR mutation status and ERCC1 and TS expression were evaluated through direct DNA sequencing and immunohistochemical analyses, respectively. The EGFR mutation status and ERCC1 and TS expression were the significant predictors of clinical outcomes. The EGFR mutation status was the main outcome predictor for overall survival (OS) benefits in the overall population. Further exploratory ERCC1 and TS expression analyses were conducted to provide additional insights. Low TS expression was predictive of improved OS of patients with negative EGFR-mutated advanced AC-NSCLC, whereas high ERCC1 expression resulted in poor OS in patients with positive EGFR-mutated advanced AC-NSCLC. TS and ERCC1 expression levels were effective prognostic factors for negative and positive EGFR-mutated AC-NSCLC, respectively. In conclusion, the present results indicate that the EGFR mutation status and TS and ERCC1 expression can be used as the predictors of OS after subsequent second-line treatments for AC-NSCLC.

Integrating TYMS, KRAS and BRAF testing in patients with metastatic colorectal cancer.

AIMTo investigate the impact of thymidylate synthase (TYMS), KRAS and BRAF in the survival of metastatic colorectal cancer (mCRC) patients treated with chemotherapy.METHODSClinical data were collected retrospectively from records of consecutive patients with mCRC treated with fluoropyrimidine-based chemotherapy from 1/2005 to 1/2007. Formalin-fixed paraffin-embedded tissues were retrieved for analysis. TYMS genotypes were identified with restriction fragment analysis PCR, while KRAS and BRAF mutation status was evaluated using real-time PCR assays. TYMS gene polymorphisms of each of the 3’ untranslated region (UTR) and 5’UTR were classified into three groups according to the probability they have for high, medium and low TYMS expression (and similar levels of risk) based on evidence from previous studies. Univariate and multivariate survival analyses were performed.RESULTSThe analysis recovered 89 patients with mCRC (46.1% de novo metastatic disease and 53.9% relapsed). Of these, 46 patients (51.7%) had colon cancer and 43 (48.3%) rectal cancer as primary. All patients were treated with fluoropyrimidine-based chemotherapy (5FU or capecitabine) as single-agent or in combination with irinotecan or/and oxaliplatin or/and bevacizumab. With a median follow-up time of 14.8 mo (range 0-119.8), 85 patients (95.5%) experienced disease progression, and 63 deaths (70.8%) were recorded. The 3-year and 5-year OS rate was 25.4% and 7.7% while the 3-year progression-free survival rate was 7.1%. Multivariate analysis of TYMS polymorphisms, KRAS and BRAF with clinicopathological parameters indicated that TYMS 3’UTR polymorphisms are associated with risk for disease progression and death (P < 0.05 and P < 0.03 respectively). When compared to tumors without any del allele (genotypes ins/ins and ins/loss of heterozygosity (LOH) linked with high TYMS expression) tumors with del/del genotype (low expression group) and tumors with ins/del or del/LOH (intermediate expression group) have lower risk for disease progression (HR = 0.432, 95%CI: 0.198-0.946, P < 0.04 and HR = 0.513, 95%CI: 0.287-0.919, P < 0.03 respectively) and death (HR = 0.366, 95%CI: 0.162-0.827, P < 0.02 and HR = 0.559, 95%CI: 0.309-1.113, P < 0.06 respectively). Additionally, KRAS mutation was associated independently with the risk of disease progression (HR = 1.600, 95%CI: 1.011-2.531, P < 0.05). The addition of irinotecan in 1st line chemotherapy was associated independently with lower risk for disease progression and death (HR = 0.600, 95%CI: 0.372-0.969, P < 0.04 and HR = 0.352, 95%CI: 0.164-0.757, P < 0.01 respectively).CONCLUSIONThe TYMS genotypes ins/ins and ins/LOH associate with worst prognosis in mCRC patients under fluoropyrimidine-based chemotherapy. Large prospective studies are needed for validation of our findings.

P2.03a-007 Pem/CBP/Bev Followed by Pem/Bev in Hispanic Patients with NSCLC: Outcomes According to Combined Score of TS, ERCC1 and VEGF Expression

To evaluate the efficacy and safety of pemetrexed, carboplatin and bevacizumab (PCB) followed by maintenance pemetrexed and bevacizumab (PB) in chemotherapy-naïve patients with stage IV non-squamous non-small cell lung cancer (NSCLC) through the influence of thymidylate synthase (TS), ERCC1 and VEGF mRNA expression on several outcomes. The primary endpoints were the overall response rate (ORR), progression-free survival (PFS) and overall survival (OS). Patients were administered pemetrexed (500 mg/m2), carboplatin (AUC, 5.0 mg/ml/min) and bevacizumab (7.5 mg/kg) intravenously every three weeks for up to four cycles. Maintenance pemetrexed and bevacizumab was administered until disease progression or unacceptable toxicity. One hundred forty-four Hispanic patients with a median follow-up of 13.8 months and a median number of maintenance cycles of 6 (range, 1- 32) were assessed. The ORR among the patients was 66% (95% CI, 47% to 79%). The median progression-free and overall survival (OS) rates were 7.9 months (95% CI, 5.9-10.0 months) and 21.4 months (95% CI, 18.3 to 24.4 months), respectively. Median TS, ERCC1 and VEGF mRNA levels were 1.45 (range, 0.17–2.52), 0.58 (range, 0.44-1.20), and 2.72 (range, 1.84-3.21), respectively. OS was significantly higher in patients with the lowest TS mRNA levels [29.6 months (95% CI 26.2-32.9) compared with those with higher levels 9.3 months (95% CI 6.6-12.0); p=0.0001]. ERCC1 mRNA levels also influenced the OS [median for ERCC1 mRNA˂0.58 28.7 months (95% CI 26.3-31.2) vs. ERCC1 mRNA˃0.58 11.1 months (95% CI 9.6-12.7); p=0.0001] as well as VEGF mRNA levels [median OS for VEGF mRNA˂2.72 26.4 months (95% CI 22.8-30.0) vs. VEGF mRNA˃2.72 18.2 months (95% CI 8.4-27.9); p=0.009]. TS mRNA did not influence treatment response, however the ORR was significantly higher in patients with low levels of ERCC1 (p = 0.003) and elevated VEGF (p = 0.005). Multivariate analysis found that TS mRNA levels (p=0.0001), VEGF mRNA levels (p=0.007) and PS (p=0.014) were independent prognostic factors. Overall, PCB followed by maintenance pemetrexed and bevacizumab was in Hispanic patients with non-squamous NSCLC. This regimen was associated with prolonged OS, particularly in patients with low TS, ERCC1 and VEGF mRNA expression. These biomarkers alone or in combination may be useful to assess the prognosis of patients with NSCLC treated with CBP/Pem/Bev.

Higher Tissue Levels of Thymidylate Synthase Determined by ELISA Are Associated with Poor Prognosis of Patients with Lung Cancer.

Thymidylate synthase (TS) is essential in thymidylate biosynthesis and DNA replication. Dihydropyrimidine dehydrogenase (DPD) is a rate-limiting enzyme in pyrimidine catabolism and is important in catabolism of 5-fluorouracil (5-FU). The significance of TS and DPD expressed in lung cancer remains controversial. Here we analyzed the relationship between TS and DPD expression and clinicopathological features of lung cancer. Enzyme-linked immunosorbent assays (ELISAs) were used to measure TS and DPD levels in paired tumor and non-tumor lung tissues obtained from 168 patients (107 adenocarcinomas, 39 squamous cell carcinomas, and 22 others), who had operations at the Shinshu University Hospital from 2004 to 2007 and were followed up for a median of 57.0 months. TS and DPD expression levels were higher in tumor tissues, and TS expression levels were significantly lower in adenocarcinomas than those in other subtypes. In addition, patients with low TS levels survived longer compared with patents with high TS levels. By contrast, DPD expression levels were not correlated with overall patient survival. Importantly, patients with low TS and DPD levels exhibited significantly prolonged survival than those with high TS and DPD. Among the 168 patients, 59 patients were treated with tegafur-uracil (UFT), a DPD-inhibitory fluoropyrimidine, and the UFT-treated patients with high TS and high DPD levels showed worst prognosis. Our study demonstrates a significant correlation between low TS expression levels and long-term prognosis of patients with lung cancer. Thus, ELISA is a clinically useful method to measure TS and DPD expression in lung cancer tissues.

A Study of Thymidylate Synthase Expression as a Biomarker for Resectable Colon Cancer: Alliance (Cancer and Leukemia Group B) 9581 and 89803.

Tumor levels of thymidylate synthase (TS), a target of 5-fluorouracil (5-FU)-based chemotherapy for colorectal cancer, have been studied as a predictive or prognostic biomarker with mixed results. Tumor TS levels were prospectively evaluated in two adjuvant therapy trials for patients with resected stage II or III colon cancer. TS expression was determined by standard immunohistochemistry and by automated quantitative analysis. Tumor mismatch repair deficiency (MMR-D) and BRAF c.1799T > A (p.V600E) mutation status were also examined. Relationships between tumor TS, MMR-D, and BRAF mutation status, overall survival (OS), and disease-free survival (DFS) were investigated in the subset of stage III patients. Patients whose tumors demonstrated high TS expression experienced better treatment outcomes, with DFS hazard ratio (HR) = 0.67, 95% confidence interval (CI) = 0.53, 0.84; and OS HR = 0.68, 95% CI = 0.53, 0.88, for high versus low TS expression, respectively. No significant interaction between TS expression and stage was observed (DFS: interaction HR = 0.94; OS: interaction HR = 0.94). Tumors with high TS expression were more likely to demonstrate MMR-D (22.2% vs. 12.8%; p = .0003). Patients whose tumors demonstrated both high TS and MMR-D had a 7-year DFS of 77%, compared with 58% for those whose tumors had low TS and were non-MMR-D (log-rank p = .0006). Tumor TS expression did not predict benefit of a particular therapeutic regimen. This large prospective analysis showed that high tumor TS levels were associated with improved DFS and OS following adjuvant therapy for colon cancer, although tumor TS expression did not predict benefit of 5-FU-based chemotherapy. The Oncologist 2017;22:107-114Implications for Practice: This study finds that measurement of tumor levels of thymidylate synthase is not helpful in assigning specific adjuvant treatment for colorectal cancer. It also highlights the importance of using prospective analyses within treatment clinical trials as the optimal method of determining biomarker utility.

The role of thymidylate synthase in non-small cell lung cancer treated with pemetrexed continuation maintenance therapy

Pemetrexed continuation maintenance therapy has been proven to be beneficial for patients with advanced non-squamous non-small cell lung cancer (NSCLC). However, the eligibility criteria for maintenance treatment are too simple. This study sought to evaluate thymidylate synthase (TS) as a predicting biomarker for pemetrexed continuation maintenance treatment in NSCLC. Specimens were collected from 87 patients treated with pemetrexed continuation maintenance therapy before and after four-cycle induction chemotherapy. Real-time quantitative PCR was used to detect TS expression in tissues. The TS expression level was correlated with characteristic clinical data, radiographic response, progression-free time (PFS) and overall survival (OS). Low total TS expression (<8.47) was associated with improved PFS (median: 4.7 months vs. 3.5 months, p = 0.034) and improved OS (time from random assignment: 16.4 months vs. 11.7 months, p = 0.026; time from induction: 19.7 months vs. 14.8 months, p = 0.022). Our results indicate that in NSCLC patients treated with pemetrexed continuation maintenance therapy, low TS expression is associated with improved PFS and OS.

Efficacy of crizotinib and pemetrexed-based chemotherapy in Chinese NSCLC patients with ROS1 rearrangement.

BackgroundROS1 rearrangement is a novel molecular subgroup of non-small-cell lung cancer (NSCLC). This study aimed to investigate the efficacy of crizotinib and pemetrexed-based chemotherapy in Chinese NSCLC patients with ROS1 rearrangement.ResultsA total of 2309 patients received ROS1 fusion detection and 51(2.2%) patients had ROS1 rearrangement. There was no significant difference between ROS1 fusion-positive and fusion-negative cohorts in demographic data. For the ROS1 fusion-positive patients, crizotinb-treated group had a higher overall response rate (ORR, 80.0%), disease control rate (DCR, 90.0%) and longer progression-free survival (PFS, 294 days) compared with the rates in pemetrexed-treated group (ORR, 40.8%; DCR, 71.4%; PFS, 179 days) and non-pemetrexed-treated group (ORR, 25.0%; DCR, 47.7%; PFS, 110 days). Besides, ORR, DCR and PFS were similar in three major ROS1 fusion partners. For the first-line treatment, patients received pemetrexed had a significant longer PFS than those received non-pemetrexed chemotherapy (209 vs. 146 days, P = 0.0107). In pemetrexed-treated cohorts, ROS1-positive patients with low TS expression had a statistically significant longer PFS than those with high TS expression (184 vs. 110 days, P = 0.0105).Materials and methodsWe retrospectively identified patients with NSCLC who were screened for ROS1 fusion using multiplex reverse transcription-polymerase chain reaction (RT-PCR) from October 2013 to February 2016. The thymidylate synthase (TS) mRNA levels were tested using quantitative real-time RT-PCR.ConclusionsCrizotinib was also highly active at treating Chinese NSCLC patients with ROS1 rearrangement. TS expression could predict the efficacy of pemetrexed-based therapy in ROS1 fusion-positive patients.

1240P - Randomized phase 2 trial of gefitinib with and without pemetrexed as first-line therapy in East Asian patients with advanced, epidermal growth factor receptor (EGFR) mutation-positive (mt+), nonsquamous (NS) non-small cell lung cancer (NSCLC): Translational research and interim overall survival (OS)

The primary analysis of this open-label, randomized, multicenter, phase 2 study found significantly longer progression-free survival (PFS) for pemetrexed plus gefitinib (P + G) vs gefitinib alone (G) in 191 East Asian patients with EGFR mt+ NS NSCLC (adjusted hazard ratio [HR]: 0.68; 95% confidence interval [CI]: 0.48-0.96; P = 0.029). Translational research, interim OS data and updated safety results are reported. Treatment-naive patients with advanced, EGFR mt+ (local laboratory testing), NS NSCLC were randomized (2:1) to receive P + G (pemetrexed 500 mg/m2, Day 1 of 21-day cycles plus gefitinib 250 mg/day; n = 126) or G (gefitinib 250 mg/day; n = 65). Mandatory pretreatment tissue samples were assayed for EGFR mutations by central evaluation (CE) (n = 159) and thymidylate synthase (TS) by immunohistochemistry (n = 146). OS in the intention-to treat (ITT) population and correlation of biomarkers with clinical outcomes were analyzed by adjusted Cox regression. By CE, 149/159 patients (93.7%) were EGFR mt+. In the CE+ population, PFS was longer for P + G (n = 96) vs G (n = 53) (HR: 0.72; 95% CI: 0.48-1.06; P = 0.093), consistent with the primary analysis based on local testing. In patients with low (n = 67) and high (n = 79) TS expression, the PFS HR was 0.47 (95% CI: 0.26-0.87) and 0.83 (95% CI: 0.47-1.46), respectively; the interaction effect was not statistically significant (P = 0.177). At the interim OS analysis (80 events, 58% censoring), OS was not significantly different for P + G vs G (HR: 0.79; 95% CI: 0.49-1.28; P = 0.342). Postdiscontinuation systemic therapy was common (P + G: 62.7%; G: 72.3%). The incidence of grade 3/4 drug-related adverse events was significantly (P = 0.002) higher for P + G (42.9%) vs G (20.0%). The PFS HR for the CE+ population was consistent with the primary ITT analysis. No significant interaction effects were seen for TS. At this interim analysis, there was no statistical difference in OS for P + G vs G. Final OS analyses will be reported when 130 events have occurred.

1283P - The role of thymidylate synthase in non-small-cell lung cancer treated with pemetrexed continuation maintenance therapy

Pemetrexed continuation maintenance therapy has been proven to be beneficial for patients with advanced non-squamous non-small cell lung cancer (NSCLC). However, the eligibility criteria for maintenance treatment are too simple. This study sought to evaluate thymidylate synthase (TS) as a predicting biomarker for pemetrexed continuation maintenance treatment in NSCLC. Specimens were collected from 87 patients treated with pemetrexed continuation maintenance therapy before and after four-cycle induction chemotherapy. Real-time quantitative PCR was used to detect TS expression in tissues. The TS expression level was correlated with characteristic clinical data, radiographic response, progression-free time (PFS) and overall survival (OS). Low total TS expression (<8.47) was associated with improved PFS (median: 4.7 months vs. 3.5 months, p = 0.034) and improved OS (time from random assignment: 16.4 months vs. 11.7 months, p = 0.026; time from induction: 19.7 months vs. 14.8 months, p = 0.022). Our results in...

Immunohistochemical analysis of thymidylate synthase expression in gastric carcinoma: correlation with clinicopathological parameters and survival.

The correlation of thymidylate synthase (TS) expression in gastric cancers with tumor histology and prognostic or predictive information remains unclear. Most studies have involved Asian populations, with few conducted in European cohorts. Moreover, all published studies analyze TS expression using semi-quantitative methods. This retrospective study evaluated the association of TS expression in tumor cells with gastric carcinoma histological type, with selected clinicopathological parameters, and with the prognosis of patients who underwent surgical treatment. TS expression was detected using immunochemistry and objectively assessed by computerized image analysis of tumor cells in 100 gastric cancers. We found that high TS expression was significantly more common in intestinal than in diffuse type of gastric cancer according to Lauren classification (P=0.0003); in type I carcinomas compared to type IV according to Goseki classification (P=0.002); and in gastric cancers in men than women (P=0.04). Low TS expression was found more often in carcinomas in the middle and lower third of the stomach than in cancers in the upper third of the stomach (P=0.009 and P=0.001, respectively). In the subgroup of 25 patients without lymph node metastases (stage I+II), high TS expression was associated with better DFS (83% for high TS expression versus 38,5% for low TS expression, P=0.03). The results (1) indicate significant correlation between the Lauren and Goseki histopathological classifications of gastric cancer and TS expression in tumor cells, (2) suggest that high TS expression may be a positive prognostic marker with regard to DFS in patients with gastric cancer without involvement of regional lymph nodes who underwent radical surgical treatment and were not treated with preoperative chemotherapy. Prognostic results need confirmation in larger cohorts.