DPD status and fluoropyrimidines-based treatment: high activity matters too.

BACKGROUND: Dihydropyrimidine dehydrogenase (DPD) status is an indicator of a marked risk for toxicity following fluoropyrimidine (FP)-based chemotherapy. This notion is well-established for low DPD status but little is known about the clinical impact of high DPD activity. This study examined the possible link between high intrinsic lymphocytic DPD activity and overall survival, progression free survival and response to FP-based treatment in patients treated in our institution. METHODS: Lymphocytic DPD activity was assessed in a group of 136 patients receiving FP-based chemotherapy from 2004 to 2016. There were 105 digestive (77.2%), 24 breast (17.6%) and 7 head and neck cancers (5.2%). Cox or logistic regression models were applied with adjustment on all confounding factors that could modify OS, PFS or response. All models were stratified on the three cancer locations. A cut-off for DPD activity was assessed graphically and analytically. RESULTS: An optimal cut-off for DPD activity at 0.30 nmol/min/mg protein was identified as the best value for discriminating survivals and response. In multivariate analysis, individual lymphocytic DPD activity was significantly related to overall survival (p = 0.013; HR: 3.35 CI95%[1.27-8.86]), progression-free survival (p < 0.001; HR: 3.15 CI95%[1.75-5.66]) and response rate (p = 0.033; HR: 0.33 CI95%[0.12-0.92]) with a marked detrimental effect associated with high DPD activity. CONCLUSIONS: DPD status screening should result in a two-pronged approach with FP dose reduction in case of low intrinsic DPD and, inversely, an increased FP dose for high intrinsic DPD. In a context of personalized FP-based treatment, this innovative strategy needs to be prospectively validated.

Pharmacogenetic tailoring of irinotecan-based first-line chemotherapy in metastatic colorectal cancer: results of a pilot study.

BACKGROUND: Tolerability to irinotecan may be explained by pharmacogenomic polymorphisms. The purpose of this pharmacogenetic trial was to study the relevance of thymidylate synthase (TS) genotyping and of the isoform 1A1 of uridine diphosphate glucuronosyltransferase (UGT1A1) in order to tailor a combination chemotherapy regimen of 5-fluorouracil, leucovorin and irinotecan (FOLFIRI) in metastatic colorectal cancer. PATIENTS AND METHODS: Patients with favourable TS and UGT1A1 profiles received high-dose (HD) FOLFIRI. Patients with TS-3R/3R could not receive HD-FOLFIRI, and those with UGT1A1-7/7 received standard FOLFIRI. The endpoints were overall response rate and safety. RESULTS: Sixty-nine patients were enrolled in the study. Sixty-five patients received chemotherapy. Twenty patients (30.8%) achieved a partial response. The haematological toxicity was less in the HD-FOLFIRI subgroup. Patients having received HD-FOLFIRI did not experience increased levels of nausea-vomiting, asthenia or alopecia. Diarrhoea was more frequent with HD-FOLFIRI. CONCLUSION: The genotypic assessment allowed a safer use of HD-FOLFIRI. Further investigations may target patients who benefit from intensification.

Methylenetetrahydrofolate reductase gene polymorphisms and response to fluorouracil-based treatment in advanced colorectal cancer patients.

Methylenetetrahydrofolate reductase (MTHFR) controls intracellular CH2FH4 concentrations (required for optimal fluoropyrimidine efficacy) by irreversibly converting CH2FH4 into 5-methyltetrahydrofolate. MTHFR 677C>T and 1298A>C polymorphisms are linked to altered enzyme activity. Thus, mutated MTHFR tumours should, in theory, be more sensitive to 5-fluorouracil (5FU) than wild-type tumours. MTHFR polymorphisms in position 677 and 1298 were analysed in 98 colorectal cancer patients with unresectable liver metastases (57 men, 41 women, mean age 64 years) receiving 5FU-folinic acid. 677C>T and 1298A>C genotypes were determined simultaneously by melting curve analyses on liver metastases. 677C>T genotype distribution was 46.9% wt/wt, 34.7% wt/mut and 18.4% mut/mut; that of 1298A>C was 52.0% wt/wt, 35.7% wt/mut and 12.3% mut/mut. The response rate was not related to 1298A>C genotype but was significantly linked to 677C>T genotype (response rate: 40%, 21% and 56% in wt/wt, wt/mut and mut/mut, respectively; P = 0.040), with an increased response rate in mut/mut tumours relative to wt/wt (odds ratio = 1.88). Thymidylate synthase activity measured in metastases was a significant predictor of 5FU responsiveness and the addition of the 677C>T genotype improved model prediction. MTHFR 1298A>C polymorphism was significantly linked to specific survival, with homozygous mutated patients having the worst prognosis (P = 0.009, relative risk = 2.48 in mut/mut versus wt/wt). MTHFR 1298A>C genotype remained a significant predictor in a multivariate analysis including metastasis characteristics. The results suggest that MTHFR genotypes are relevant and independent factors of patient outcome in 5FU-based treatment of advanced colorectal cancer.

Persistent twenty-four hour changes in liver and bone marrow despite suprachiasmatic nuclei ablation in mice.

Rest-activity or cortisol rhythms can be altered in cancer patients, a condition that may impair the benefits from a timed delivery of anticancer treatments. In rodents, the circadian pattern in rest-activity is suppressed by the destruction of the suprachiasmatic nuclei (SCN) in the hypothalamus. We sought whether such ablation would result in a similar alteration of cellular rhythms known to be relevant for anticancer drug chronopharmacology. The SCN of 77 B6D2F(1) mice synchronized with 12 h of light and 12 h of darkness were destroyed by electrocoagulation [SCN(-)], while 34 animals were sham operated. Activity and body temperature were recorded by telemetry. Blood and organs were sampled at one of six circadian times for determinations of serum corticosterone concentration, blood leukocyte count, reduced glutathione (GSH), and dihydropyrimidine dehydrogenase (DPD) mRNA expression in liver and cell cycle phase distribution of bone marrow cells. Sham-operated mice displayed significant 24-h rhythms in rest-activity and body temperature, whereas such rhythms were found in none and in 15% of the SCN(-) mice, respectively. SCN lesions markedly altered the rhythmic patterns in serum corticosterone and liver GSH, which became nonsinusoidal. Liver DPD mRNA expression and bone marrow cell cycle phase distribution displayed similar 24-h sinusoidal patterns in sham-operated and SCN(-) mice. These results support the existence of another light-dark entrainable pacemaker that can coordinate cellular functions in peripheral organs. They suggest that the delivery of anticancer treatments at an optimal time of day may still be beneficial, despite suppressed rest-activity or cortisol rhythms.

ZD1839 (Iressa) modifies the activity of key enzymes linked to fluoropyrimidine activity: rational basis for a new combination therapy with capecitabine.

PURPOSE: The efficacy of new oral fluoropyrimidines, including capecitabine, is improved in cells expressing high levels of thymidine phosphorylase (TP) and low levels of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase. We used a human head and neck cancer cell line (CAL33) to examine the influence of cell cycle modifications on TS, TP, and dihydropyrimidine dehydrogenase activity. EXPERIMENTAL DESIGN: Cells were exposed to the epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 (Iressa(2)) and 5'-deoxy-5-fluorouridine (5'-DFUR), alone and in combination, for up to 96 h, and modifications in cell cycle, enzyme activity, and gene expression were examined. RESULTS: ZD1839 (24- to 72-h exposure) markedly reduced proliferation and caused a rapid increase in G(0)-G(1) and a decrease in S phase; a 40-fold decrease in TS activity at 24 h and a 2.5-fold increase in TP activity at 48 h were observed. A significant link between TP activity and expression was observed (r(2) = 0.98; P = 0.0068). Additional investigations pointed out an increased cellular production of 5-fluorouracil anabolites from 5'-DFUR when cells were preincubated with ZD1839. Dose-effect curves of ZD1839 and 5'-DFUR, alone and in combination, were examined. Combination indices for ZD1839 + 5'-DFUR were 0.58 +/- 0.1 and 0.63 +/- 0.1 for 50% survival and 25% survival, respectively. Additional investigations pointed out an increased cellular production of 5-fluorouracil anabolites from 5'-DFUR when cells were preincubated with ZD1839. CONCLUSIONS: These data demonstrate a strong synergistic interaction between ZD1839 and 5'-DFUR when ZD1839 is applied before or concurrently with 5'-DFUR. Such a drug combination would have two advantages: (a) the theoretical advantage of tumor selectivity of epidermal growth factor receptor-targeted therapy; and (b) the practical advantage of a combination therapy that could be administered p.o.

Oxaliplatin-5-fluorouracil and ionizing radiation. Importance of the sequence and influence of p53 status.

OBJECTIVES AND METHODS: The association oxaliplatin (OXA)-5-fluorouracil/folinic acid (FUFA) is currently a standard first-line treatment for advanced colorectal cancer. The main objective of this experimental study was to examine the cytotoxic effects resulting from the addition of ionizing radiation (Rgamma) to the combination OXA-FUFA on 2 human colon cancer cell lines (SW403, p53 wild type and WiDr, p53 mutated). A clinically relevant drug sequence was used consisting in OXA during 2 h followed by FUFA over 24 h. The impact of the position of radiation (1 and 4 Gy) was tested: radiation 2 h before drug application, in the middle of the drug application or 24 h after the drug application. RESULTS: Both cell lines exhibited similar dose response curves to Rgamma alone, WiDr being more radio-sensitive than SW403 (IC50: 4.8 Gy and 7 Gy, respectively). The effects of Rgamma-drug combinations were assessed using a conventional isobolographic method and by computing a potentiation factor (F) defined as the ratio of IC50 drug combinations/IC50 drug combinations combined with Rgamma. The results from both calculation methods concurred: the combination of OXA-FUFA with Rgamma led to additive-antagonistic effects for the p53 mutated cell line (WiDr), whatever the sequence. In contrast, for the p53 wild type cell line (SW403), additive-synergistic effects were observed with, in this case, an optimal position for Rgamma occurring when applied before or at mid-drug application. CONCLUSIONS: These results could be taken into consideration for an optimal design of clinical protocols associating Rgamma and OXA-FUFA.

Prognostic value of tumoral thymidylate synthase and p53 in metastatic colorectal cancer patients receiving fluorouracil-based chemotherapy: phenotypic and genotypic analyses.

PURPOSE: The aim of this multicenter prospective study was to evaluate the role of intratumoral parameters related to fluorouracil (FU) sensitivity in 103 metastatic colorectal cancer patients receiving FU-folinic acid. PATIENTS AND METHODS: Liver metastatic biopsy specimens were obtained for all patients and primary tumor biopsy specimens for 54 patients. Thymidylate synthase (TS), folylpolyglutamate synthetase, and dihydropyrimidine dehydrogenase were measured by radioenzymatic assays; TS promoter polymorphism (2R/2R v 2R/3R v 3R/3R) was determined by polymerase chain reaction; and p53 protein and mutations were analyzed by immunoluminometric assay and denaturing gradient gel electrophoresis, respectively. RESULTS: p53 mutations were observed in 56.7% of metastases. TS activity was significantly higher in 2R/3R tumors as compared with 2R/2R or 3R/3R. TS activity in metastasis was the only parameter linked to clinical responsiveness (responders exhibited the lower TS, P =.047). Univariate Cox analyses demonstrated that TS activity in primary tumor (the greater the TS, the poorer the survival; P =.040), TS promoter polymorphism in primary tumor (risk of death of 2R/3R v 2R/2R, 2.68; P =.035), and p53 stop mutation in metastasis (risk of death of stop mutations v wild type, 3.14; P =.018) were the only significant biologic predictors of specific survival. Stepwise analysis did not discriminate between TS activity and TS polymorphism. CONCLUSION: Present results confirm the value of tumoral TS activity for predicting FU responsiveness, point out the importance of detailed p53 mutation analysis for predicting survival, and suggest that TS genotype in primary tumor carries a prognostic value similar to that of TS activity.