Thymidylate synthase gene amplification predicts pemetrexed resistance in patients with advanced non-small cell lung cancer

Background. Thymidylate synthase (TYMS) expression in lung cancer tissue affects the therapeutic efficacy of pemetrexed (PMT). TYMS protein expression is primarily assessed using immunohistochemistry (IHC), but this method is not suitable for accurate quantitative analysis. It is not known whether the analysis of TYMS gene copy number using fluorescence in situ hybridization (FISH) is a useful method for assessment of TYMS expression. Patients and methods. The participants were patients with chemo-naïve advanced NSCLC treated with PMT plus carboplatin (CBDCA) in prospective clinical phase II study. TYMS expression was evaluated in 40 patients by gene copy number and protein expression using FISH and IHC. Therapeutic efficacy was evaluated by investigating the response rate (RR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). Results. TYMS gene amplification was detected in 8 patients (32 %) among 25 patients who could be evaluated for TYMS gene copy number. There were no patients with complete or partial response in the TYMS amplified group. RR and DCR were lower in the TYMS amplified group compared with the TYMS unamplified group (0 versus 35.3 %, p = 0.0539, 62.5 versus 94.1 %, p = 0.0443). PFS and OS were reduced in the TYMS amplified group. The analysis of TYMS gene copy number had higher sensitivity and specificity compared with TYMS protein expression (76.2 versus 50.0 %, 75.0 versus 66.7 %). Conclusion. The analysis of TYMS gene copy number is more suitable than TYMS protein expression for assessment of TYMS expression. TYMS gene amplification predicts outcome of patients receiving PMT with advanced NSCLC (AU)

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New developments in malaria diagnostics: monoclonal antibodies against Plasmodium dihydrofolate reductase-thymidylate synthase, heme detoxification protein and glutamate rich protein.

Currently available rapid diagnostic tests (RDTs) for malaria show large variation in sensitivity and specificity, and there are concerns about their stability under field conditions. To improve current RDTs, monoclonal antibodies (mAbs) for novel malaria antigens have been developed and screened for their possible use in new diagnostic tests. Three antigens, glutamate rich protein (GLURP), dihydrofolate reductase-thymidylate synthase (DHFR-TS) and heme detoxification protein (HDP), were selected based on literature searches. Recombinant antigens were produced and used to immunize mice. Antibody-producing cell lines were subsequently selected and the resulting antibodies were screened for specificity against Plasmodium falciparum and Plasmodium vivax. The most optimal antibody couples were selected based on antibody affinity (expressed as dissociation constants, KD) and detection limit of crude antigen extract from P. falciparum 3D7 culture. The highest affinity antibodies have KD values of 0.10 nM ± 0.014 (D5) and 0.068 ± 0.015 nM (D6) for DHFR-TS mAbs, 0.10 ± 0.022 nM (H16) and 0.21 ± 0.022 nM (H18) for HDP mAbs and 0.11 ± 0.028 nM (G23) and 0.33 ± 0.093 nM (G22) for GLURP mAbs. The newly developed antibodies performed at least as well as commercially available histidine rich protein antibodies (KD of 0.16 ± 0.13 nM for PTL3 and 1.0 ± 0.049 nM for C1-13), making them promising reagents for further test development.

Response prediction in metastasised colorectal cancer using intratumoural thymidylate synthase: results of a randomised multicentre trial.

BACKGROUND: Molecular markers to predict response to 5-fluorouracil (FU)-based treatment of recurrent or metastasised colorectal cancer (mCRC) are not established. The aim of this trial was to determine the value of thymidylate synthase (TS), a key enzyme of DNA synthesis and target of 5-FU, to predict response to chemotherapy of mCRC. METHODS: Tumour tissue was obtained from 168 patients with mCRC for relative thymidylate synthase (TS) mRNA quantitation. Patients were randomised to receive either 5-FU/folinic acid (FA, FUFA) alone or in combination with irinotecan 5-fluorouracil/folinic acid and irinotecan (FOLFIRI) stratified by TS (low versus high). Primary end-point was overall response to first-line treatment among TS high patients. All parties, except for the randomisation centre, were blinded for TS status. RESULTS: Biopsies (n=168) were taken without complications. TS levels were available for 147 patients (87.5%). Analysing response to FUFA and FOLFIRI in the per protocol set (n=119) after un-blinding TS in the data base revealed a trend to better overall response to FOLFIRI (9/19, 47%) in TS high compared to FUFA (5/23, 22%, p=0.077). In patients with biopsies taken from liver lesions (n=91) overall response to FOLFIRI and FUFA in TS high was 53% (9/17) and 18% (3/17), respectively (p=0.035). In patients with low TS, no remarkable difference in overall response to FOLFIRI and FUFA was observed. CONCLUSIONS: Taking a pre-treatment biopsy is a safe and feasible procedure in mCRC. After validation of our data in a larger group TS determination may have the potential to better help direct systemic treatment in patients with primarily non-resectable mCRC.

Valor pronóstico y predictivo de la timidilato sintetasa (TS) en pacientes con cáncer de colon / Prognostic and predictive value of the thymidylate synthase (TS) in patients with colon cancer

El cáncer colo-rectal es uno de los cánceres más comunes en el mundo actual, para lo cual el 5-Fluorouracilo (5-FU) es usualmente parte importante del tratamiento quimioterapéutico. La Timidilato Sintetasa (TS), es la enzima blanco para el 5-FU. Estudios recientes sugieren que la TS puede predecir el pronóstico y el éxito de la terapia basada en el 5-FU. El propósito de este estudio retrospectivo fue determinar la expresión de la TS en muestras de biopsias de cáncer de colon incluidas en parafina, mediante la técnica de inmunohistoquímica y correlacionarla con factores de riesgo, antígeno carcinoembrionario (CEA), CA-19-9, evolución del paciente y respuesta al tratamiento con 5-FU. La población en estudio consistió en 34 muestras de biopsias de cáncer de colon obtenidas de pacientes quienes fueron tratados con 5-FU y Leucovorina. A las muestras de adenocarcinomas colónicas incluidas en parafina se les realizó la detección de TS a través de inmunohistoquímica. Los pacientes en cuyos tumores había una alta expresión de la TS, mostraron una sobrevida significativamente menor comparado son aquellos pacientes que mostraron baja expresión de la enzima en sus tumores (p=0,004). La expresión de la TS puede ser utilizada como un importante marcador pronóstico de sobrevida y de respuesta a la quimioterapia en pacientes con cáncer colo-rectal.

Colorectal cancer is one of the most common cancers in the world today, for which a 5-fluorouracil (5-FU) is usually an important part of the chemotherapeutic treatment. The thymidylate synthase (TS), is the target enzyme for 5-FU. Recent studies suggest that TS can predict the prognosis and the success of therapy based on 5-FU. The purpose of this retrospective study was to determine the expression of TS in samples from biopsies of colon cancer in paraffin, using the technique of immunohistochemistry and its correlation with risk factors, carcinoembryonic antigen (CEA), CA-19-9, patients evolution and response to treatment with 5-FU. The study population consisted of 34 biopsy samples obtained from colon cancer patients who were treated with 5-FU and Leucovorin. A sample of colonic adenocarcinoma in paraffin was performed to detect TS through immunohistochemistry. Patients whose tumours had a high expression of TS showed a significantly lower survival rate compared with those patients who showed low expression of the enzyme in their tumours (p = 0.004). The expression of TS can be used as an important marker of survival prognosis and response to chemotherapy in patients with colon cancer.

New drugs and combinations in the palliative treatment of colon and rectal cancer.

Colorectal cancer (CRC) is a common disease. The overall survival has improved only marginally in recent decades despite advances in surgery and early detection. Potentially curative resection at disease presentation can be performed only in 70-80% of the patients, and overall survival at 5 years is less than 60%. Advanced disease is associated with a poor prognosis. Treatment for advanced colorectal cancer has nevertheless made progress in the last few years. Systemic chemotherapy doubles the survival of these patients compared to untreated controls. Chemotherapy has demonstrated effective palliation, improvement of quality of life (QoL) and symptom improvement in such patients. For nearly four decades, fluorouracil (5FU) has been the mainstay of treatment. New compounds active against colorectal cancer are now available. Several studies on this topic are ongoing.

Enzyme-catalyzed therapeutic agent (ECTA) design: activation of the antitumor ECTA compound NB1011 by thymidylate synthase.

The in vivo administration of enzyme-inhibiting drugs for cancer and infectious disease often results in overexpression of the targeted enzyme. We have developed an enzyme-catalyzed therapeutic agent (ECTA) approach in which an enzyme overexpressed within the resistant cells is recruited as an intracellular catalyst for converting a relatively non-toxic substrate to a toxic product. We have investigated the potential of the ECTA approach to circumvent the thymidylate synthase (TS) overexpression-based resistance of tumor cells to conventional fluoropyrimidine [i.e. 5-fluorouracil (5-FU)] cancer chemotherapy. (E)-5-(2-Bromovinyl)-2'-deoxy-5'-uridyl phenyl L-methoxyalaninylphosphoramidate (NB1011) is a pronucleotide analogue of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdU), an antiviral agent known to be a substrate for TS when in the 5'-monophosphorylated form. NB1011 was synthesized and found to be at least 10-fold more cytotoxic to 5-FU-resistant, TS-overexpressing colorectal tumor cells than to normal cells. This finding demonstrates that the ECTA approach to the design of novel chemotherapeutics results in compounds that are selectively cytotoxic to tumor cell lines that overexpress the target enzyme, TS, and therefore may be useful in the treatment of fluoropyrimidine-resistant cancer.