Thymidylate synthase expression determines pemetrexed targets and resistance development in tumour cells

Pilot Study of High-Dose Pemetrexed in Patients with Progressive Chordoma

PURPOSE

Chordomas are ultrarare tumors of the axial spine and skull-base without approved systemic therapy. Most chordomas have negative expression of thymidylate synthase (TS), suggesting a potential for responding to the antifolate agent pemetrexed, which inhibits TS and other enzymes involved in nucleotide biosynthesis. We evaluated the therapeutic activity and safety of high-dose pemetrexed in progressive chordoma.

PATIENTS AND METHODS

Adult patients with previously treated, progressive chordoma participated in an open-label, single-institution, single-arm, pilot clinical trial of intravenous pemetrexed 900 mg/m2 every 3 weeks and supportive medications of folic acid, vitamin B12, and dexamethasone. The primary endpoint was objective response rate according to RECIST v1.1. Secondary endpoints included adverse events, progression-free survival (PFS), tumor molecular profiles, and alterations in tissue and blood-based biomarkers.

RESULTS

Fifteen patients were enrolled and the median number of doses administered was 15 (range, 4-31). One patient discontinued treatment due to psychosocial issues after four cycles and one contracted COVID-19 after 13 cycles. Of the 14 response-evaluable patients, 2 (14%) achieved a partial response and 10 (71%) demonstrated stable disease. Median PFS was 10.5 months (95% confidence interval: 9 months-undetermined) and 6-month PFS was 67%. Adverse events were expected and relatively mild, with one grade 3 creatinine increased, and one each of grade 3 and 4 lymphopenia. No grade 5 adverse events, unexpected toxicities, or dose-limiting toxicities were observed. Several patients reported clinical improvement in disease-related symptoms.

CONCLUSIONS

High-dose pemetrexed appears tolerable and shows objective antitumor activity in patients with chordoma. Phase II studies of high-dose pemetrexed are warranted.

Activity of pemetrexed in pre-clinical chordoma models and humans

Chordomas are rare slow growing tumors, arising from embryonic remnants of notochord with a close predilection for the axial skeleton. Recurrence is common and no effective standard medical therapy exists. Thymidylate synthase (TS), an intracellular enzyme, is a key rate-limiting enzyme of DNA biosynthesis and repair which is primarily active in proliferating and metabolically active cells. Eighty-four percent of chordoma samples had loss of TS expression which may predict response to anti-folates. Pemetrexed suppresses tumor growth by inhibiting enzymes involved in folate metabolism, resulting in decreased availability of thymidine which is necessary for DNA synthesis. Pemetrexed inhibited growth in a preclinical mouse xenograft model of human chordoma. We report three cases of metastatic chordoma that had been heavily treated previously with a variety of standard therapies with poor response. In two cases, pemetrexed was added and objective responses were observed on imaging with one patient on continuous treatment for > 2 years with continued shrinkage. One case demonstrated tumor growth after treatment with pemetrexed. The two cases which had a favorable response had a loss of TS expression, whereas the one case with progressive disease had TS present. These results demonstrate the activity of pemetrexed in recurrent chordoma and warrant a prospective clinical trial which is ongoing (NCT03955042).

Regulation of thymidylate synthase: an approach to overcome 5-FU resistance in colorectal cancer

Thymidylate synthase is the rate-limiting enzyme required for DNA synthesis and overexpression of this enzyme causes resistance to cancer cells. Long treatments with 5-FU cause resistance to Thymidylate synthase targeting drugs. We have also compiled different mechanisms of drug resistance including autophagy and apoptosis, drug detoxification and ABC transporters, drug efflux, signaling pathways (AKT/PI3K, RAS-MAPK, WNT/β catenin, mTOR, NFKB, and Notch1 and FOXM1) and different genes associated with resistance in colorectal cancer. We can overcome 5-FU resistance in cancer cells by regulating thymidylate synthase by natural products (Coptidis rhizoma), HDAC inhibitors, mTOR inhibitors, Folate antagonists, and several other drugs which have been used in combination with TS inhibitors. This review is a compilation of different approaches reported for the regulation of thymidylate synthase to overcome resistance in colorectal cancer cells.

Upregulation of Thymidylate Synthase Induces Pemetrexed Resistance in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an invasive malignancy that develops in the pleural cavity, and antifolates are used as chemotherapeutics for treating. The majority of antifolates, including pemetrexed (PMX), inhibit enzymes involved in purine and pyrimidine synthesis. MPM patients frequently develop drug resistance in clinical practice, however the associated drug-resistance mechanism is not well understood. This study was aimed to elucidate the mechanism underlying resistance to PMX in MPM cell lines. We found that among the differentially expressed genes associated with drug resistance (determined by RNA sequencing), TYMS expression was higher in the established resistant cell lines than in the parental cell lines. Knocking down TYMS expression significantly reduced drug resistance in the resistant cell lines. Conversely, TYMS overexpression significantly increased drug resistance in the parental cells. Metabolomics analysis revealed that the levels of dTMP were higher in the resistant cell lines than in the parental cell lines; however, resistant cells showed no changes in dTTP levels after PMX treatment. We found that the nucleic acid-biosynthetic pathway is important for predicting the efficacy of PMX in MPM cells. The results of chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR) assays suggested that H3K27 acetylation in the 5′-UTR of TYMS may promote its expression in drug-resistant cells. Our findings indicate that the intracellular levels of dTMP are potential biomarkers for the effective treatment of patients with MPM and suggest the importance of regulatory mechanisms of TYMS expression in the disease.

Efficacy of S-1 after pemetrexed in patients with non-small cell lung cancer: A retrospective multi-institutional analysis

Background

S‐1 and pemetrexed (PEM) are key treatments for non‐small cell lung cancer (NSCLC). However, the mechanism of anticancer activity of S‐1 and PEM is similar. Cross‐resistance between S‐1 and PEM is of concern. This exploratory study was designed to evaluate the treatment effect of S‐1 following PEM‐containing treatment.

Methods

This retrospective study included patients with advanced (c‐stage III or IV, UICC seventh edition) or recurrent NSCLC who received S‐1 monotherapy following the failure of previous PEM‐containing chemotherapy at six hospitals in Japan. The primary endpoint of the study was the overall response rate (ORR). The secondary endpoint was the disease control rate (DCR), time to treatment failure (TTF), progression‐free survival (PFS), and overall survival (OS).

Results

A total of 53 NSCLC patients met the criteria for inclusion in the study. Forty‐six patients had adenocarcinoma (88.7%) and no patients had squamous cell carcinoma. Thirty‐one patients (58.5%) received the standard S‐1 regimen and 18 patients (34.0%) received the modified S‐1 regimen. ORR was 1.9% (95% confidence interval [CI]: 0.00%–10.1%). Median TTF, PFS, and OS were 65, 84, and 385 days, respectively.

Conclusions

Although there were several limitations in this study, the ORR of S‐1 after PEM in patients with nonsquamous (non‐SQ) NSCLC was low compared to the historical control. One of the options in the future might be to avoid S‐1 treatment in PEM‐treated patients who need tumor shrinkage.

Genetic Variants in One-Carbon Metabolism Pathway Predict Survival Outcomes of Early-Stage Non-Small Cell Lung Cancer

BACKGROUND

This study was conducted to investigate the association between genetic variants in one-carbon metabolism and survival outcomes of surgically resected non-small cell lung cancer (NSCLC).

METHODS

We genotyped 41 potentially functional variants of 19 key genes in the one-carbon metabolism pathway among 750 NSCLC patients who underwent curative surgery. The association between genetic variants and overall survival (OS)/disease-free survival (DFS) were analyzed.

RESULTS

Among the 41 single-nucleotide polymorphisms (SNPs) analyzed, 4 SNPs (MTHFD1L rs6919680T>G and rs3849794T>C, MTR rs2853523C>A, and MTHFR rs4846049G>T) were significantly associated with survival outcomes. MTHFD1L rs6919680T>G and MTR rs2853523C>A were significantly associated with better OS (adjusted hazard ratio [aHR] = 0.73, 95% confidence interval [CI] = 0.54-0.99, p = 0.04) and worse OS (aHR = 2.14, 95% CI = 1.13-4.07, p = 0.02), respectively. MTHFD1L rs3849794T>C and MTHFR rs4846049G>T were significantly associated with worse DFS (aHR = 1.41, 95% CI = 1.08-1.83, p = 0.01; and aHR = 1.97, 95% CI = 1.10-3.53, p = 0.02, respectively). When the patients were divided according to histology, the associations were significant only in squamous cell carcinoma (SCC), but not in adenocarcinoma (AC). In SCC, MTHFD1L rs6919680T>G and MTR rs2853523C>A were significantly associated with better OS (aHR = 0.64, 95% CI = 0.41-1.00, p = 0.05) and worse OS (aHR = 2.77, 95% CI = 1.11-6.91, p = 0.03), respectively, and MTHFD1L rs3849794T>C and MTHFR rs4846049G>T were significantly associated with worse DFS (aHR = 1.73, 95% CI = 1.17-2.56, p = 0.01; and aHR = 2.78, 95% CI = 1.12-6.88, p = 0.03, respectively).

CONCLUSIONS

Our results suggest that the genetic variants in the one-carbon metabolism pathway could be used as biomarkers for predicting the clinical outcomes of patients with early-stage NSCLC.

The deubiquitinating enzyme UCHL1 promotes resistance to pemetrexed in non-small cell lung cancer by upregulating thymidylate synthase

Rationale: Resistance to pemetrexed (PEM)-based chemotherapy is a major cause of progression in non-small cell lung cancer (NSCLC) patients. The deubiquitinating enzyme UCHL1 was recently found to play important roles in chemoresistance and tumor progression. However, the potential roles and mechanisms of UCHL1 in PEM resistance remain unclear.

Methods: Bioinformatics analyses and immunohistochemistry were used to evaluate UCHL1 expression in NSCLC specimens. Kaplan-Meier analysis with the log-rank test was used for survival analyses. We established PEM-resistant NSCLC cell lines by exposing them to step-wise increases in PEM concentrations, and in vitro and in vivo assays were used to explore the roles and mechanisms of UCHL1 in PEM resistance using the NSCLC cells.

Results: In chemoresistant tumors from NSCLC patients, UCHL1 was highly expressed and elevated UCHL1 expression was strongly associated with poor outcomes. Furthermore, UCHL1 expression was significantly upregulated in PEM-resistant NSCLC cells, while genetic silencing or inhibiting UCHL1 suppressed resistance to PEM and other drugs in NSCLC cells. Mechanistically, UCHL1 promoted PEM resistance in NSCLC by upregulating the expression of thymidylate synthase (TS), based on reduced TS expression after UCHL1 inhibition and re-emergence of PEM resistance upon TS restoration. Furthermore, UCHL1 upregulated TS expression, which mitigated PEM-induced DNA damage and cell cycle arrest in NSCLC cells, and also conferred resistance to PEM and other drugs.

Conclusions: It appears that UCHL1 promotes PEM resistance by upregulating TS in NSCLC cells, which mitigated DNA damage and cell cycle arrest. Thus, UCHL1 may be a therapeutic target for overcoming PEM resistance in NSCLC patients.

Blood mRNA expression of REV3L and TYMS as potential predictive biomarkers from platinum-based chemotherapy plus pemetrexed in non-small cell lung cancer patients

PURPOSE

Therapeutic options for cancer patients have increased in the last years, although drugs resistance problem remains unresolved. Genetic background in individual susceptibility to cancer treatment could influence the therapy responses. The aim of this study was to explore the feasibility of using blood 4 genes (AEG-1, BRCA-1, REV3L and TYMS) expression levels as a predictor of the efficacy of pemetrexed therapy in patients with advanced non-small cell lung cancer.

METHODS

Sixteen patients from the Medical Oncology Department at "12 de Octubre" Hospital, were included in the study. Total mRNA was isolated from blood samples, and gene expression was analyzed by RT-qPCR. A panel of lung tumor cell lines were used in cell proliferation tests and siRNA-mediated silencing assays.

RESULTS

Similarity between blood gene expression levels and protein expression in matched tumor tissue was observed in 54.54% (REV3L) and 81.81% (TYMS) of cases. Gene expression of REV3L and TYMS in blood correlated directly and inversely, respectively, with progression-free survival and overall survival in the patients from our cohort. In tumor cell lines, the knockdown of REV3L conferred resistance to pemetrexed treatment, and the TYMS silencing increased the pemetrexed sensitivity of tumor cells.

CONCLUSIONS

The use of peripheral blood samples for expression quantification of interest genes is an affordable method with promising results in the evaluation of response to pemetrexed treatment. Therefore, expression levels of REV3L and TYMS genes might be used as predictive biomarkers in advanced NSCLC patients.

High UDG and BRCA1 expression is associated with adverse outcome in patients with pemetrexed treated non-small cell lung Cancer

OBJECTIVE

The antifolate chemotherapy agent pemetrexed has been widely used to treat non-small-cell-lung-cancer (NSCLC), but there is no clinically validated biomarker to select patients likely to respond. The aim of this study was to assess two proteins involved in DNA repair mechanisms, uracil DNA glycosylase (UDG) and BRCA1 as potential prognostic biomarkers in NSCLC patients treated with pemetrexed-based chemotherapy.

MATERIAL AND METHODS

Formalin-fixed-paraffin-embedded tumor specimens from 119 patients with advanced NSCLC treated with pemetrexed between 2004 and 2011 were retrospectively analyzed. Expression of UDG, BRCA1, and known prognostic factors ALK, TTF-1, thymidylate synthase and folylpolyglutamate synthase was assessed by immunohistochemistry using H-SCORE (product of percent stained cells and intensity of expression). Progression-free (PFS) and overall survival (OS) served as reference endpoint.

RESULTS

Most NSCLC tumor samples had UDG positivity in at least 5% of tumor cells and 34% samples had more than 50% positive tumor cells. Using the median expression value as threshold, high UDG expression (H-SCORE≥75) was significantly associated with shorter median PFS (3-year PFS 7% vs. 37%, p = 0.045) and a trend for shorter OS (3-year OS 15% vs 42%, p = 0.066) compared to patients with low UDG. In multivariable Cox analysis, the association between high UDG and shorter PFS was close to statistically significant (p = 0.08) at a significance level of 0.05 after controlling for age, gender, ALK- and TTF1-status with hazard ratio of 2.1. Grouping patients according to combined UDG and BRCA1 expression, patients with a profile of UDG^high/BRCA1^high had the shortest PFS and OS compared to all other patient groups (p = 0.007 and 0.02, respectively).

CONCLUSION

Our results demonstrate an important prognostic role for high UDG expression in pemetrexed-treated NSCLC patients, in addition to its previously reported role in pemetrexed cytotoxicity. High UDG expression was predictive of shorter PFS and OS, and patients with a combined profile of UDG^high/BRCA1^high had the poorest outcome following pemetrexed treatment.

Proteomic and Bioinformatic Studies for the Characterization of Response to Pemetrexed in Platinum Drug Resistant Ovarian Cancer

Proteomics and bioinformatics are a useful combined technology for the characterization of protein expression level and modulation associated with the response to a drug and with its mechanism of action. The folate pathway represents an important target in the anticancer drugs therapy. In the present study, a discovery proteomics approach was applied to tissue samples collected from ovarian cancer patients who relapsed after the first-line carboplatin-based chemotherapy and were treated with pemetrexed (PMX), a known folate pathway targeting drug. The aim of the work is to identify the proteomic profile that can be associated to the response to the PMX treatment in pre-treatement tissue. Statistical metrics of the experimental Mass Spectrometry (MS) data were combined with a knowledge-based approach that included bioinformatics and a literature review through ProteinQuest™ tool, to design a protein set of reference (PSR). The PSR provides feedback for the consistency of MS proteomic data because it includes known validated proteins. A panel of 24 proteins with levels that were significantly different in pre-treatment samples of patients who responded to the therapy vs. the non-responder ones, was identified. The differences of the identified proteins were explained for the patients with different outcomes and the known PMX targets were further validated. The protein panel herein identified is ready for further validation in retrospective clinical trials using a targeted proteomic approach. This study may have a general relevant impact on biomarker application for cancer patients therapy selection.

Dasatinib modulates sensitivity to pemetrexed in malignant pleural mesothelioma cell lines

Background

Thymidylate synthase (TS), one of the key enzymes for thymidine synthesis, is a target of pemetrexed (PEM), a key agent for the systemic therapy of malignant pleural mesothelioma (MPM) and its overexpression has been correlated to PEM-resistance. In MPM, experimental data report activation of the c-SRC tyrosine kinase suggesting it as a potential target to be further investigated.

Results

MPM cell lines showed different sensitivity, being MSTO the most and REN the least sensitive to PEM. REN cells showed high levels of both TS and SRC: dasatinib inhibited SRC activation and suppressed TS protein expression, starting from 100 nM dose, blocking the PEM-induced up regulation of TS protein levels. Dasatinib treatment impaired cells migration, and both sequential and co-administration with PEM significantly increased apoptosis. Dasatinib pretreatment improved sensitivity to PEM, downregulated TS promoter activity and, in association with PEM, modulated the downstream PI3K-Akt-mTOR signaling.

Cell lines and Methods

In three MPM cell lines (MPP89, REN and MSTO), the effects of c-SRC inhibition, in correlation with TS expression and PEM sensitivity, were evaluated. PEM and dasatinib, a SRC inhibitor, were administered as single agents, in combination or sequentially. Cell viability, apoptosis and migration, as well as TS expression and SRC activation have been assessed.

Conclusions

These data indicate that dasatinib sensitizes mesothelioma cells to PEM through TS down-regulation.

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.

Astrocyte-elevated gene-1 confers resistance to pemetrexed in non-small cell lung cancer by upregulating thymidylate synthase expression

Previous studies have suggested that astrocyte-elevated gene-1 (AEG-1) contributes to the mechanisms of resistance to various chemotherapeutics. In this study, we investigated whether AEG-1 expression level correlated with that of thymidylate synthase (TS), as higher TS expression is known to be associated with the resistance to pemetrexed chemotherapy in patients with advanced lung adenocarcinoma. Using pemetrexed-resistant lung adenocarcinoma PC-9 cell line, we demonstrated that transfection of AEG-1 siRNA lowered TS expression and decreased pemetrexed IC₅₀ value. In contrast, overexpression of AEG-1 was associated with increased expression of TS and higher pemetrexed IC₅₀ value. Immunohistochemical staining of clinical biopsy samples showed that patients with lower AEG-1 expression had longer overall survival time. Moreover, analysis of repeated biopsy samples revealed that an increase in the TS level from baseline to disease progression was significantly associated with the elevation of AEG-1 expression. In conclusion, our data demonstrated that TS expression might be regulated by AEG-1 and that increased expression of these proteins contributes to lung cancer disease progression and may be associated with the development of resistance to pemetrexed.

Impact of platinum/pemetrexed combination versus other platinum-based regimens on adjuvant chemotherapy in resected lung adenocarcinoma

For advanced non-squamous non-small cell lung cancer (NSCLC), although platinum/pemetrexed is known to result in a longer survival compared with other regimens, the outcome in the adjuvant setting is still unknown. In this study, the difference of the disease-free survival (DFS) between lung adenocarcinoma patients treated with platinum/pemetrexed and with other platinum-based doublets was concerned. A total of 389 radically resected lung adenocarcinoma patients received adjuvant chemotherapy with platinum/pemetrexed chemotherapy (Group A, n = 143) or other third generation platinum-based regimens (Group B, n = 246) were analyzed in terms of DFS. Propensity score matching (PSM) allowed generation of best matched pairs for the two categories. DFS was proved to be considerably better in pemetrexed doublets group (P = 0.0079); and platinum/pemetrexed was found to be associated with lower rates of several hematological and non-hematological adverse events (AEs), when compared with gemcitabine containing chemotherapy (leukopenia: RR 0.514, p = 0.001; neutropenia: RR 0.688, p = 0.002), or taxanes-doublets treatment (leukopenia: RR 0.685, p = 0.019; neutropenia: RR 0.805, p = 0.032). For patients with radically resected pulmonary adenocarcinoma, adjuvant chemotherapy with platinum/pemetrexed results in a better DFS and a less clinical toxicity in comparison with non-pemetrexed based doublets.

The ERK-ZEB1 pathway mediates epithelial-mesenchymal transition in pemetrexed resistant lung cancer cells with suppression by vinca alkaloids

High thymidylate synthase (TS) level in cancer tissue is considered to result in resistance to pemetrexed therapy for advanced stages of nonsquamous non-small cell lung cancers. To further investigate the mechanism of pemetrexed resistance and potential prognostic outcomes in lung cancer, we established pemetrexed-resistant lung adenocarcinoma cell sublines from CL1 harboring a mutated TP53 gene (R248W) and A549 harboring wild-type TP53. We found the TS expression is upregulated in both pemetrexed-resistant sublines and the reduced TS level achieved through shRNA inhibition resulted in higher pemetrexed sensitivity. We also demonstrated that the acquisitions of pemetrexed resistance enhances epithelial–mesenchymal transition (EMT) in vivo with a mice animal model and in vitro with CL1 and A549 sublines, which was associated with upregulation of ZEB1 which, in turn, downregulates E-cadherin and upregulates fibronectin. When ERK1/2 phosphorylation was reduced by an inhibitor (U0126) or siRNA inhibition, both pemetrexed-resistant sublines reduced their migration and invasion abilities. Therefore, the ERK-mediated pathways induce apoptosis with pemetrexed treatment, and may in turn mediate EMT when cancer cells are resistant to pemetrexed. We further demonstrated that the growth of pemetrexed-resistant tumors could be inhibited by vinblastine in vivo and vincristine in vitro. Our data indicate that pemetrexed resistance could be relieved by non-cross-resistant chemotherapeutic drugs such as vinca alkaloids and might be independent to TP53 status. Furthermore, the phosphorylation of ERK was reduced by vincristine. This finding provides a new insight for overcoming pemetrexed resistance and metastasis by application of vinca alkaloids.

Thymidylate synthase expression as a predictive biomarker of pemetrexed sensitivity in advanced non-small cell lung cancer

Background

Although it has been suggested that a high level of thymidylate synthase (TYMS) gene expression in malignant tumors is related to reduced sensitivity to the antifolate drug pemetrexed, no direct evidence for such an association has been demonstrated in routine clinical samples from patients treated with the drug. The purpose of this study was to quantitatively assess the impact of TYMS gene expression in tumor cells as a predictor of the efficacy of pemetrexed therapy in patients with advanced non-small cell lung cancer (NSCLC) treated at our institution.

Methods

Sixty-two NSCLC patients were included in this study: 16 patients received platins-pemetrexed as first-line NSCLC, and 46 pemetrexed in monotherapy as second- or subsequent-line treatment. Total mRNA was isolated and the expression of TYMS was analyzed by RT-qPCR. TYMS levels were calibrated against expression in normal lung tissue.

Results

TYMS overexpression was detected in 61 % of patients and low expression in 39 %. The response rate for patients with low TYMS expression was 0.29 compared with 0.03 in patients with overexpression (P = 0.025). A significant benefit was observed in patients with low expression both in time to progression (average TTP = 56 vs. 23 months, P = 0.001) and in overall survival (average OS = 60 vs. 25 months, P = 0.002).

Conclusions

TYMS overexpression in tumor cells correlated with a reduced response to pemetrexed-containing chemotherapy and might be used as a predictive biomarker in advanced NSCLC patients.

The Effectiveness of Pemetrexed Monotherapy Depending on Polymorphisms in TS and MTHFR Genes as Well as Clinical Factors in Advanced NSCLC Patients

In NSCLC, second-line chemotherapy using pemetrexed or docetaxel has limited efficacy and should be dedicated to selected groups of patients. Pemetrexed is an antifolate compound with the ability to inhibit enzymes (TS, DHFR and GARFT) involved in pyrimidine and purine synthesis. The objective of this study was to evaluate the association between polymorphisms of TS and MHFR genes and clinical outcomes in NSCLC patients treated with pemetrexed monotherapy. DNA was isolated from peripheral blood of 72 non-squamous NSCLC patients treated with pemetrexed. Using PCR and RFLP methods, the variable number of tandem repeats (VNTR), the G > C SNP in these repeats and insertion/deletion polymorphism of TS gene as well as 677C > T SNP in MTHFR gene were analyzed and correlated with disease control rate, progression-free survival and overall survival (OS) of NSCLC patients. Carriers of 2R/3R(G), 3R(C)/3R(G), 3R(G)/3R(G) genotypes showed significantly more frequent early progression than carriers of 2R/2R, 2R/3R(C), 3R(C)/3R(C) genotypes of TS gene (p < 0.05). Among carriers of triple 28 bp tandem repeats (3R) in TS gene and C/C genotype of MTHFR gene a significantly shorter OS was observed (HR = 3.07; p = 0.003). In multivariate analysis, significantly higher risk of death was observed in carriers of both 3R/3R genotype in TS and C/C genotype in 677C > T SNP in MTHFR (HR = 3.85; p < 0.005) as well as in patients with short duration of response to first-line chemotherapy (HR = 2.09; p < 0.005). Results of our study suggested that genetic factors may have a high predictive and prognostic value (even greater than clinical factors) for patients treated with pemetrexed monotherapy.

Blocking the epithelial-to-mesenchymal transition pathway abrogates resistance to anti-folate chemotherapy in lung cancer

Anticancer therapies currently used in the clinic often can neither eradicate the tumor nor prevent disease recurrence due to tumor resistance. In this study, we showed that chemoresistance to pemetrexed, a multi-target anti-folate (MTA) chemotherapeutic agent for non-small cell lung cancer (NSCLC), is associated with a stem cell-like phenotype characterized by an enriched stem cell gene signature, augmented aldehyde dehydrogenase activity and greater clonogenic potential. Mechanistically, chemoresistance to MTA requires activation of epithelial-to-mesenchymal transition (EMT) pathway in that an experimentally induced EMT per se promotes chemoresistance in NSCLC and inhibition of EMT signaling by kaempferol renders the otherwise chemoresistant cancer cells susceptible to MTA. Relevant to the clinical setting, human primary NSCLC cells with an elevated EMT signaling feature a significantly enhanced potential to resist MTA, whereas concomitant administration of kaempferol abrogates MTA chemoresistance, regardless of whether it is due to an intrinsic or induced activation of the EMT pathway. Collectively, our findings reveal that a bona fide activation of EMT pathway is required and sufficient for chemoresistance to MTA and that kaempferol potently regresses this chemotherapy refractory phenotype, highlighting the potential of EMT pathway inhibition to enhance chemotherapeutic response of lung cancer.

Clinical evaluation of postoperative chemotherapy based on genetic testing in patients with stage IIIA non-small cell lung cancer

Background

We performed a retrospective analysis to evaluate whether a postoperative chemotherapy selection method based on four tumoral gene expression tests would improve prognosis in patients with stage IIIA non‐small cell lung cancer (NSCLC) after surgery.

Methods

Between January 2007 and July 2011, 148 patients with stage IIIA NSCLC underwent radical lobectomy with four cycles of adjuvant postoperative chemotherapy. Forty‐five patients had tailored treatment plans based on the results of tumoral gene expression tests. The tests consisted of quantitative real‐time polymerase chain reaction analyses to measure the messenger ribonucleic acid levels of the excision repair cross‐complementing gene 1, ribonucleotide reductase Ml, type III β‐tubulin, and thymidylate synthase genes in tumor tissues. One hundred and three patients received conventional chemotherapy. Disease responses were assessed after two cycles and every three months after the first four cycles of chemotherapy. The one and two‐year survival rates and diesease‐free survival (DFS) rates were recorded, and the adverse effects documented.

Results

The one and two‐year DFS rates in the genetically tested group were better than those in the non‐tested group, and the differences were statistically significant (P < 0.05). The two‐year Kaplan–Meier DFS curve analysis results were significantly better in the genetically tested group (X² = 8.228, P = 0.004). The adverse effects during the treatments were not significantly different (P > 0.05) between the two groups.

Conclusions

The chemotherapy selection method based on four tumoral gene expression tests demonstrated its feasibility to improve the efficacy of adjuvant postoperative chemotherapy and benefit stage IIIA NSCLC patients by yielding better DFS without increasing the adverse effects of chemotherapy.

Clinical effectiveness and clinical toxicity associated with platinum-based doublets in the first-line setting for advanced non-squamous non-small cell lung cancer in Chinese patients: a retrospective cohort study

Background

Real-world evidence lacks for clinical effectiveness and clinical toxicity associated with platinum-based doublets in the first-line setting for advanced non-squamous non-small cell lung cancer (advNS-NSCLC) in Chinese patients.

Methods

Patients receiving first-line chemotherapy for advNS-NSCLC in four Chinese tertiary care hospitals from 2007 to 2012 were retrospectively identified for chart review. Propensity score methods created best matched pairs for platinum/pemetrexed versus other platinum-based doublets for head-to-head comparisons of early treatment discontinuation (completed treatment cycles <4), treatment failure (progressive disease or early treatment discontinuation), and adverse events (AE). Conventional multiple logistic regression analyses were also performed to confirm the impact of the studied platinum-based doublets on early treatment discontinuation, treatment failure, and hematological AE using vinorelbine/platinum as reference.

Results

1,846 patients were included to create propensity score matched treatment groups for platinum/pemetrexed versus docetaxel (95 pairs), paclitaxel (118 pairs), gemcitabine (199 pairs), and vinorelbine (72 pairs)-contained doublet, respectively. Platinum/pemetrexed was associated with significantly lower risks of early treatment discontinuation (odds ratio (OR) ranged from 0.239, p = 0.001 relative to platinum/docetaxel to 0.389, p = 0.003 relative to platinum/paclitaxel) and treatment failure (OR ranged from 0.257, p < 0.001 relative to platinum/paclitaxel to 0.381, p < 0.001 relative to platinum/gemcitabine) than the other four studied doublets. Platinum/pemetrexed was also associated with several significantly lower hematological AE rates, such as versus platinum/paclitaxel (any hematological AE: OR 0.508, p = 0.032), platinum/gemcitabine (i.e., any hematological AE: OR 0.383, p < 0.001; anemia: OR 0.357, p < 0.001; thrombocytopenia: OR 0.345, p < 0.001) or platinum/vinorelbine (i.e., neutropenia: OR 0.360, p = 0.046; anemia: OR 0.181, p = 0.014) in matched patients. Further conventional logistic regression analyses indicated that pemetrexed/platinum was ranked lowest for the risks of early treatment discontinuation (OR 0.326, p < 0.001), treatment failure (OR 0.460, p < 0.001), and any hematological AE (OR 0.329, p < 0.001).

Conclusions

Pemetrexed plus platinum had significantly superior clinical effectiveness as compared to the other platinum-based doublets with third-generation cytotoxic agents and was also associated with several lower hematological toxicity rates than gemcitabine or vinorelbine-based doublet in the first-line setting for advNS-NSCLC in Chinese patients.