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G J Peters

Publications and source records attributed to G J Peters.

At least 73 records · Page 4Linked to original sources
PubMed2002

Induction of thymidylate synthase as a 5-fluorouracil resistance mechanism.

Thymidylate synthase (TS) is a key enzyme in the de novo synthesis of 2'-deoxythymidine-5'-monophosphate (dTMP) from 2'-deoxyuridine-5'-monophosphate (dUMP), for which 5,10-methylene-tetrahydrofolate (CH(2)-THF) is the methyl donor. TS is an important target for chemotherapy; it is inhibited by folate and nucleotide analogs, such as by 5-fluoro-dUMP (FdUMP), the active metabolite of 5-fluorouracil (5FU). FdUMP forms a relatively stable ternary complex with TS and CH(2)THF, which is further stabilized by leucovorin (LV). 5FU treatment can induce TS expression, which might bypass dTMP depletion. An improved efficacy of 5FU might be achieved by increasing and prolonging TS inhibition, a prevention of dissociation of the ternary complex, and prevention of TS induction. In a panel of 17 colon cancer cells, including several variants with acquired resistance to 5FU, sensitivity was related to TS levels, but exclusion of the resistant variants abolished this relation. For antifolates, polyglutamylation was more important than the intrinsic TS level. Cells with low p53 levels were more sensitive to 5FU and the antifolate raltitrexed (RTX) than cells with high, mutated p53. Free TS protein down-regulates its own translation, but its transcription is regulated by E2F, a cell cycle checkpoint regulator. Together, this results in low TS levels in stationary phase cells. Although cells with a low TS might theoretically be more sensitive to 5FU, the low proliferation rate prevents induction of DNA damage and 5FU toxicity. TS levels were not related to polymorphisms of the TS promoter. Treatment with 5FU or RTX rapidly induced TS levels two- to five-fold. In animal models, 5FU treatment resulted in TS inhibition followed by a two- to three-fold TS induction. Both LV and a high dose of 5FU not only enhanced TS inhibition, but also prevented TS induction and increased the antitumor effect. In patients, TS levels as determined by enzyme activity assays, immunohistochemistry and mRNA expression, were related to a response to 5FU. 5FU treatment initially decreased TS levels, but this was followed by an induction, as seen with an increased ratio of TS protein over TS-mRNA. The clear retrospective relation between TS levels and response now forms the basis for a prospective study, in which TS levels are measured before treatment in order to determine the treatment protocol.

Animals↗
PubMed2002

Patient preference and pharmacokinetics of oral modulated UFT versus intravenous fluorouracil and leucovorin: a randomised crossover trial in advanced colorectal cancer.

The aim of this study was to determine the patient's preference for oral UFT/leucovorin (LV) or intravenous (i.v.) 5-fluorouracil (5-FU)/LV chemotherapy in metastatic colorectal cancer and to compare 5-FU exposure with these two treatment options. A total of 37 previously untreated patients with advanced colorectal cancer were randomised to start treatment with either oral UFT 300 mg/m2/day plus oral LV 90 mg/day for 28 days every 5 weeks or i.v. 5-FU 425 mg/m2/day plus LV 20 mg/m2/day for 5 days every 4 weeks. For the second treatment cycle, patients were crossed-over to the alternative treatment regimen. Prior to the first and after the second therapy cycle, patients were required to complete a therapy preference questionnaire (TPQ). The pharmacokinetics of 5-FU were determined by taking blood samples on days 8, 15 or 22 and 28 for UFT and on days 1 and 5 for i.v. 5-FU. 36 patients were eligible. 84% of the patients preferred oral UFT over i.v. 5-FU. After having experienced both treatment modalities, patients indicated taking the medication at home, less stomatitis and diarrhoea, and pill over injection as the most important reasons for their preference. The area under the plasma concentration curve (AUC) for 5-FU after UFT administration was 113 microM x min on day 8, 114 on day 15 and 98 on day 28; the peak levels (Cmax) were 1.2, 1.3 and 1.0 microM, respectively. The AUC for the 5-FU/LV courses was 3083 microM x min for day 1 and 3809 for day 5 (P=0.002). The Cmax was 170.1 and 196.2 microM (P=0.06) and the clearance 2.6 and 1.9 l/min, respectively (P=0.002). Patients with metastatic colorectal cancer clearly preferred oral over i.v. chemotherapy treatment. This choice was most importantly influenced by convenience and toxicity considerations. Although i.v. bolus 5-FU leads to higher peak 5-FU concentrations and AUC values compared with oral UFT, this pharmacokinetic advantage of i.v. 5-FU seems to translate mainly into higher toxicity as seen in large randomised studies comparing oral UFT/LV with i.v. 5-FU/LV. Oral UFT/LV compares favourably with i.v. 5-FU/LV in terms of toxicity and patient's preference and leads to prolonged 5-FU exposure, which is comparable to continuous i.v. 5-FU treatment.

Adenocarcinoma↗
PubMed2002

Gemcitabine-radiotherapy in patients with locally advanced pancreatic cancer.

A feasibility study was performed to assess the toxicity and efficacy of a combination of gemcitabine-radiotherapy in patients with locally advanced pancreatic cancer (LAPC). 24 patients (15 females and 9 males) with measurable LAPC were included; the median age of the patients was 63 years (range 39-74 years). The performance status ranged from 0 to 2. Gemcitabine was administered at a dose of 300 mg/m(2), concurrent with radiotherapy, three fractions of 8 Gy, on days 1, 8 and 15. When compliance allowed, gemcitabine alone was continued thereafter, at 1000 mg/m(2), weekly times 3, every 4 weeks, depending on the response and toxicity. All patients were evaluable for toxicity and response. The objective response rate was 29.2% (1 complete remission+6 partial remissions); 12 patients had stable disease. However, 2 of the radiological partial remissions were shown to be complete remissions by pathology assessment. Median duration of response was 3 months (range 1-35+months). Median time to progression was 7 months (range 2-37+months). Median survival was 10 months (range 3-37+months). Dose reduction or omission of gemcitabine was necessary in 10 patients. Non-haematological toxicity consisted of 87.5% nausea and vomiting grade I-II, diarrhoea 54%, ulceration in stomach and duodenum 37.5% (20.8% ulceration with bleeding); 1 patient developed a fistula between the duodenum and aorta, 5 months after treatment. Anaemia grade III-IV was observed in 8.3% of the patients. Neutropenia grade III-IV was observed in 8.3%, thrombocytopenia grades III-IV in 16.7%. In 1 patient who underwent resection postchemoradiation, no viable tumour cells were found. In addition, in the patient who suddenly died of a fistula between the duodenum and aorta, no viable tumour cells were detectable at autopsy. Although the toxicity of this treatment was occasionally severe, the response and survival are encouraging and warrant further studies of this combination.

Adult↗
PubMed2002

Maintenance of ATP favours apoptosis over necrosis triggered by benzamide riboside.

A new synthetic drug, benzamide riboside (BR) exhibited strong oncolytic activity against leukemic cells in the 5-10 microM range. Higher BR-concentrations (20 microM) predominantly induced necrosis which correlated with DNA strand breaks and subsequent depletion of ATP- and dATP levels. Replenishment of the ATP pool by addition of adenosine prevented necrosis and favoured apoptosis. This effect was not a pecularity of BR-treatment, but was reproduced with high concentrations of all trans-retinoic acid (120 microM) and cyanide (20 mM). Glucose was also capable to suppress necrosis and to favour apoptosis of HL-60 cells, which had been treated with necrotic doses of BR and cyanide. Apoptosis eliminates unwanted cells without affecting the microenvironment, whereas necrosis causes severe inflammation of surrounding tissues due to spillage of cell fluids into the peri-cellular space. Thus, the monitoring and maintenance of cellular energy pools during therapeutic drug treatment may help to minimize nonspecific side effects and to improve attempted drug effects.

Adenosine↗
PubMed2002

Differential expression of cell cycle and apoptosis related proteins in colorectal mucosa, primary colon tumours, and liver metastases.

AIMS: Tumour cell growth results from a disturbance in the balance between the rate of proliferation and cell death. In this study, proteins involved in the regulation of cell cycle arrest and apoptosis were studied as possible factors responsible for uncontrolled cell growth in colorectal cancer. METHODS: The expression of proteins involved in these processes was investigated in 48 metastases from patients with colorectal cancer and compared with eight normal colon mucosa samples and 14 primary tumours. Both primary tumours and metastases were obtained from eight patients. The expression of thymidylate synthase (TS), p53, retinoblastoma protein (Rb), Fas receptor, Fas ligand, bcl-2, mcl-1, bax, and bcl-x was measured using immunohistochemistry. Proliferation was determined by Ki67 staining, whereas apoptosis was assessed by M30 immunostaining, which recognises cleaved cytokeratin 18. RESULTS: In the limited number of cases in which paired comparisons were possible, the expression of TS and Ki67 was significantly higher in metastases than in the matched primary tumour samples (p = 0.014 and 0.016, respectively), whereas Rb expression was lower in metastases than in primary tumours (p = 0.024). Fas receptor expression was high in normal mucosa but absent in primary tumours and metastases, whereas the opposite was seen for p53. The expression of bax, mcl-1, and bcl-x in normal mucosa was more apical than that seen in malignant cells, where a more diffuse expression pattern was seen (p < 0.04). Apoptosis was more abundant in primary tumours than in metastases. CONCLUSIONS: These results demonstrate that proliferation and apoptosis are disturbed during colorectal cancer progression, and this is accompanied by loss of Rb and Fas expression, the accumulation of p53 and TS, and changes in the expression patterns of bax, mcl-1, and bcl-xl.

Apoptosis↗
PubMed2001

Simultaneous determination of F-beta-alanine and beta-alanine in plasma and urine with dual-column reversed-phase high-performance liquid chromatography.

F-beta-Alanine and beta-alanine were detected in plasma and urine samples with fluorescence detection of orthophthaldialdehyde derivatives of F-beta-alanine and beta-alanine after separation with dual-column reversed-phase HPLC. The detection limits of F-beta-alanine and beta-alanine in the HPLC system were approximately 0.3 and 0.7 pmol, respectively. The procedure proved to be very reproducible with intra-assay RSDs and inter-assay RSDs being less than 8%. The usefulness of the method was demonstrated by the analysis of the F-beta-alanine and beta-alanine concentrations in plasma and urine samples from tumor patients treated with S-1 (Tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate in a molar ratio of 1:0.4:1).

Chromatography, High Pressure Liquid↗
PubMed2001

Collateral sensitivity to gemcitabine (2',2'-difluorodeoxycytidine) and cytosine arabinoside of daunorubicin- and VM-26-resistant variants of human small cell lung cancer cell lines.

Multidrug resistance (MDR), characterized by a cross-resistance to many natural toxin-related compounds, may be caused either by overexpression of a drug efflux pump such as P-glycoprotein, (P-gP), multidrug resistance proteins MRP1-3, or BCRP/MXR or, in the case of DNA topoisomerase II active drugs, by a decrease in the enzymatic activity of the target molecule termed altered topoisomerase MDR (at-MDR). However, human small cell lung carcinoma (SCLC) cell lines showed a collateral sensitivity to 2',2'-difluorodeoxycytidine (gemcitabine, dFdC) and 1-beta-D-arabinofuranosylcytosine (ara-C). H69/DAU, a daunorubicin (DAU)-resistant variant of H69 with a P-gP overexpression, and NYH/VM, a VM-26 (teniposide)-resistant variant of NYH with an at-MDR, were both 2-fold more sensitive to gemcitabine and 7- and 2-fold more sensitive to ara-C, respectively. MDR variants had a 4.3- and 2.0-fold increased activity of deoxycytidine kinase (dCK), respectively. dCK catalyzes the first rate-limiting activation step of both gemcitabine and ara-C. In addition, deoxycytidine deaminase, responsible for inactivation of dFdC and ara-C, was 9.0-fold lower in H69/DAU cells. The level of thymidine kinase 2, a mitochondrial enzyme that can also phosphorylate deoxycytidine and gemcitabine, was not significantly different between the variants. These differences most likely caused an increased accumulation of the active metabolites (dFdCTP, 2.1- and 1.6-fold in NYH/VM and H69/DAU cells, respectively) and of ara-CTP (1.3-fold in NYH/VM cells). Ara-CTP accumulation was not detectable in either H69 variant. The pools of all ribonucleoside and deoxyribonucleoside triphosphates were at least 3- to 4-fold higher in the NYH variants compared to the H69 variants; for dCTP and dGTP this difference was even larger. The higher ribonucleotide pools might explain the >10-fold higher accumulation of dFdCTP in NYH compared to H69 variants. Since dCTP is low, H69 cells might not need a high ara-CTP accumulation to inhibit DNA polymerase. This might be related to the lack of ara-CTP in H69 variants. In addition, the increased CTP, ATP, and UTP pools in the MDR variants might explain the increased ara-CTP and dFdCTP accumulation. In conclusion, the MDR variants of the human SCLC cell lines were collaterally sensitive due to an increased dCK activity, and consequently an increased ara-CTP and dFdCTP accumulation.

Adenosine Triphosphate↗
PubMed2001

Modulation of both endogenous folates and thymidine enhance the therapeutic efficacy of thymidylate synthase inhibitors.

Plasma levels of folates and thymidine in mice are about 10-fold higher than in humans and may influence the therapeutic efficacy of thymidylate synthase (TS) inhibitors, such as 5-fluorouracil (5FU) and the antifolates pemetrexed (MTA) and raltitrexed (RTX). Therefore, we tested their therapeutic efficacy in various murine tumor models, grown in mice on a normal and a folate-depleted diet, with high and low thymidine kinase (TK) levels. MTA and RTX were inactive against Colon-26-10 [doubling times gained by treatment; growth delay factor (GDF), 0.5 and 0.3, respectively], whereas 5FU was very active (GDF, >10; complete cures). Colon-26-10/F, grown in mice on a folate-depleted diet, was more sensitive to RTX and MTA (GDF, 2.1 and 1.3, respectively) but not to 5FU (GDF, 1.2); however, leucovorin reversed the effect leading to cures. Folate depletion did not reverse resistance of Colon-26A and Colon-26G (low TK) to MTA and RTX, whereas leucovorin only enhanced the 5FU effect in Colon-26A and Colon-26A/F. Folic acid at 15 mg/kg did not improve the therapeutic efficacy of MTA in folate-deficient mice. The folate-depleted diet decreased the reduced folates in Colon-26A/F and Colon-26-G/F tumors less (4-5-fold; P < 0.01) than in Colon-26-10/F tumors (8-fold; P < 0.001). Folate depletion increased TS levels 2-3-fold in all of the models and TK levels 6-fold (P < 0.01) in Colon-26G/F, explaining the lack of activity of MTA and RTX in Colon-26G/F. In contrast, TK-deficient FM3A/TK tumors were much more sensitive to RTX, MTA, and 5FU than parent FM3A tumors, which have comparable TS levels. The rate of thymidine phosphorylysis varied considerably in all of the tumors without a clear relation to antitumor activity. In conclusion, tumor folates may potentiate (5FU) or protect (antifolates). Murine tumor models should combine low folates and low thymidine rescue to optimize preclinical testing of antifolates.

Animals↗
PubMed2001

Synthesis and in vitro cytotoxicity of novel long chain busulphan analogues.

Two novel long chain alkanediol dimethanesulphonates, analogues of busulphan, were synthesized. Their in vitro cytotoxicity was evaluated against six solid tumor cell lines (A2780, H322, LL, WiDr, C26-10 and UMSCC-22B). 2-Tetradecylbutane-1,4-diol dimethanesulphonate was proved to be the most active compound exhibiting IC50 values between 20.82 and 26.36 microM.

Alkanes↗
PubMed2001

Steroids affect collateral sensitivity to gemcitabine of multidrug-resistant human lung cancer cells.

Gemcitabine is phosphorylated by deoxycytidine kinase and thymidine kinase 2 and during S-phase incorporated into DNA. The steroids cortisol and dexamethasone, which regulate cell proliferation and gene expression, are pumped out of the cell by the membrane efflux pumps P-glycoprotein and multidrug resistance-associated protein (MRP), which are blocked by verapamil. In parental non-small cell lung cancer (NSCLC) cells (SW1573), 5 microM cortisol and 100 nM dexamethasone decreased sensitivity to gemcitabine. However, both cortisol and dexamethasone only decreased sensitivity with verapamil in MRP (2R120) and P-glycoprotein (2R160) overexpressing variants. Cortisol decreased deoxycytidine kinase activity in SW1573 cells and cortisol with verapamil in 2R120 and 2R160 cells. Dexamethasone with verapamil decreased deoxycytidine kinase activity in 2R160. Cortisol decreased thymidine kinase 2 activity in 2R120 and 2R160 cells. Dexamethasone decreased thymidine kinase 2 activity in SW1573, 2R120 and 2R160 cells. In conclusion, since dexamethasone is frequently used to treat side effects of oncolytic therapy, a decrease of sensitivity to gemcitabine by steroids might be clinically relevant.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

End-joining deficiency and radiosensitization induced by gemcitabine.

The mechanism of radiosensitization by gemcitabine (2',2'-difluoro-2'-deoxycytidine, dFdC) is not exactly known. We investigated the possible role of inhibition of the repair of DNA double-strand breaks by dFdC by measuring the extent of radiosensitization in different cell lines deficient and proficient in components of nonhomologous end-joining and in the parental cell lines. Different cell lines were incubated with 0.5 and 5 microM dFdC for 4 h. Cells deficient in DNA-dependent protein-kinase catalytic subunit (V3) showed sensitization similar to that of wild-type cells (AAS) and complemented cells (V3+YAC). Ku80-deficient cells (xrs5 and xrs6) showed even more radiosensitization by dFdC as compared with wild-type CHO-K1. However, Ku80-complemented cell lines (xrs5+huKu80 and xrs6+haKu80) did not show radiosensitization. The differences in dFdC-mediated radiosensitization were not attributable to different changes in deoxynucleotide triphosphate levels and cell cycle distribution. We conclude that a functional nonhomologous end-joining pathway is not required for dFdC-mediated radiosensitization.

Animals↗
PubMed2001

Reproducible gene expression measurement among multiple laboratories obtained in a blinded study using standardized RT (StaRT)-PCR.

BACKGROUND: A method that provides standardized data and is relatively inexpensive and capable of high throughput is a prerequisite to the development of a meaningful gene expression database suitable for conducting multi-institutional clinical studies based on expression measurement. Standardized RT (StaRT)-PCR has all these characteristics. In addition, the method must be reproducible. StaRT-PCR has high intralaboratory reproducibility. The purpose of this study is to determine whether StaRT-PCR provides similar interlaboratory reproducibility. METHODS AND RESULTS: In a blinded interlaboratory study, expression of ten genes was measured by StaRT-PCR in a complementary DNA sample provided to each of four laboratories. The average coefficient of variation for interlaboratory comparison of the nine quantifiable genes was 0.48. In all laboratories, expression of one of the genes was too low to be measured. CONCLUSION: Because StaRT-PCR data are standardized and numerical and the method is reproducible among multiple laboratories, it will allow development of a meaningful gene expression database.

Binding, Competitive↗
PubMed2001

Activation of caspases and induction of apoptosis by novel ribonucleotide reductase inhibitors amidox and didox.

OBJECTIVE: Amidox and didox are two polyhydroxy-substituted benzohydroxamic acid derivatives that belong to a new class of ribonucleotide reductase (RR) inhibitors. RR is the rate-limiting enzyme for de novo deoxyribonucleotide synthesis, and its activity is significantly increased in tumor cells in proportion to the proliferation rate. Therefore, RR is a target for antitumor therapy. MATERIALS AND METHODS: HL-60 and K562 leukemia cells were treated with increasing doses of amidox and didox. Thereafter, the mode of cytotoxic drug action was determined by Hoechst 33258/propidium iodide (HO/PI) double staining, annexin binding, DNA fragmentation, and caspase activation. This was correlated to the decrease in dNTP levels. Staining with HO/PI and binding of fluorescein isothiocyanate-conjugated annexin V to externalized phosphatidylserine were used to quantify apoptosis. RESULTS: Low doses of amidox or didox resulted in an increase of apoptotic HL-60 cells within 48 hours. Higher doses (50 microM amidox or 250 microM didox) led to rapid induction of apoptosis, which could be detected as early as 4 hours after treatment. After 48 hours with these concentrations, almost 100% of the HL-60 cells died by apoptosis without an increase in necrosis. K562 cells were found to be resistant to amidox but not to didox. In HL-60 cells, upstream caspase 8 is processed in response to didox, whereas caspases 8 and 9 are processed upon amidox treatment. Didox-induced apoptosis, but not amidox-induced apoptosis, can be correlated with the decrease in dNTP levels. The results suggests that amidox induces several apoptosis mechanisms in HL-60 cells. In contrast, only caspase 9 is activated by didox in K562 cells, and because amidox hardly induces apoptosis in this cell line, no caspase cleavage is observed. CONCLUSIONS: Didox triggers distinct apoptosis pathways in HL-60 and K562 cells.

Annexin A5↗
PubMed2001

A possible role for methotrexate in the treatment of childhood acute myeloid leukaemia, in particular for acute monocytic leukaemia.

Acute myeloid leukaemia (AML) is thought to be methotrexate (MTX)-resistant. However, a small study suggested that acute monocytic leukemia (AML-M5) is sensitive to MTX. We measured MTX accumulation/polyglutamylation in 20 AML-nonM5, 37 AML-M5 and 83 common/preB-acute lymphoblastic leukaemia (c/preB-ALL) samples. Membrane transport was determined in 11 childhood AMLs (including 3 AML-M5) and in 25 c/preB-ALL samples. MTX sensitivity was determined in 23 AML-nonM5, 15 AML-M5 and 63 common/preB-ALL samples using the thymidylate synthase (TS) inhibition assay. MTX transport was higher in AML samples compared with c/preB-ALL precluding a transport defect in AML. Accumulation of long-chain polyglutamates MTX-Glu(4-6) was 3-fold lower for AML-nonM5 compared with c/preB-ALL cells (median 268 versus 889 pmol MTX-Glu(4-6)/10(9) cells; P < or = 0.001); for AML-M5 samples, median accumulation of MTX-Glu(4-6) was 0 pmol/10(9) cells (P < or = 0.001). After short-term MTX exposure, AML-nonM5 was 6-fold more resistant to MTX compared with c/preB-ALL cells (2.16 versus 0.39 microM; P < 0.001), while AML-M5 was 2-fold more resistant (P = 0.02). In both AML-nonM5 and AML-M5 cells, MTX resistance was circumvented by continuous MTX exposure (median TSI(50) values: 0.052 and 0.041 microM, respectively) compared with a c/preB-ALL value of 0.066 microM. In conclusion, AML-M5 is relatively sensitive to MTX compared with other AML-subtypes even though polyglutamylation of MTX is poor. Using continuous exposure, AML-nonM5 and AML-M5 cells were at least as sensitive to MTX as c/preB-ALL cells. This report suggests that MTX might be an overlooked drug in the treatment of childhood AML.

Antimetabolites, Antineoplastic↗
PubMed2001

5-Fluorouracil induced Fas upregulation associated with apoptosis in liver metastases of colorectal cancer patients.

BACKGROUND: In vitro, thymidylate synthase (TS) inhibition by 5-fluorouracil (5-FU) induces thymineless apoptosis possibly via Fas receptor Fas ligand interactions and cell-cycle arrest. In colorectal cancer patients we evaluated whether 5-FU administration also resulted in apoptosis and cell-cycle arrest and which proteins might be involved. PATIENTS AND METHODS: Biopsy specimens were taken from 36 patients 2, 22 or 46 hours after administration of 500 mg/m2 5-FU, and from 12 control patients who did not receive 5-FU. In frozen tissue-sections from liver metastases immunohistochemistry was performed with antibodies directed against p53, p21, E2F2, Rb, Ki67 and TS (cell-cycle related) and bax, BCL-2, BCL-x, mcl-1, PARP, caspase-3, Fas receptor and Fas ligand (apoptosis related). Apoptosis was determined by M30 immunostaining, which recognises a cleavage product of cytokeratin 18. RESULTS: Fas receptor expression was 50% higher (P = 0.036) 46 hours after 5-FU administration compared to the control group. This was associated with a 12% increase (P < 0.02) in M30 positive tumour cells and with elevation of caspase-3 and PARP expression. The expression of Ki67 and E2F2 was 30% lower after 46 hours compared to the control group, whereas TS was 56% lower after 2 hours and 32% higher again after 46 hours. No differences in the expression of the other proteins were found. CONCLUSIONS: These results suggest that 5-FU decreases proliferation status and induces apoptosis possibly via the Fas pathway. Since Fas mediated cell killing is important for cytotoxic T cells this indicates that clinical studies combining immunotherapy for activation of T cells and chemotherapy using 5-FU might be very effective.

Adenocarcinoma↗