Phase I trial of volasertib, a Polo-like kinase inhibitor, plus platinum agents in solid tumors: safety, pharmacokinetics and activity.

BACKGROUND: This trial evaluated the maximum tolerated dose (MTD), safety, pharmacokinetics, and activity of volasertib, a selective Polo-like kinase 1 inhibitor that induces mitotic arrest and apoptosis, combined with cisplatin or carboplatin in patients with advanced/metastatic solid tumors (NCT00969761; 1230.6). METHODS: Sequential patient cohorts (3 + 3 dose-escalation design) received a single infusion of volasertib (100-350 mg) with cisplatin (60-100 mg/m(2)) or carboplatin (area under the concentration versus time curve [AUC]4-AUC6) on day 1 every 3 weeks for up to six cycles. Sixty-one patients received volasertib/cisplatin (n = 30) or volasertib/carboplatin (n = 31) for a median of 3.5 (range, 1-6) and 2.0 (range, 1-6) treatment cycles, respectively. RESULTS: The most common cycle 1 dose-limiting toxicities (DLTs) were thrombocytopenia, neutropenia and fatigue. MTDs (based on cycle 1 DLTs) were determined to be volasertib 300 mg plus cisplatin 100 mg/m(2) and volasertib 300 mg plus carboplatin AUC6. Co-administration did not affect the pharmacokinetics of each drug. Partial responses were observed in two patients in each arm. Stable disease was achieved in 11 and six patients treated with volasertib/cisplatin and volasertib/carboplatin, respectively. CONCLUSIONS: Volasertib plus cisplatin or carboplatin at full single-agent doses was generally manageable and demonstrated activity in heavily pretreated patients with advanced solid tumors.

HPLC determination of serum pteridine pattern as biomarkers.

Pteridinic derivatives are important biomolecules considered as biomarkers for several diseases, especially in cancer and infectious pathologies. A new fluorimetric-HPLC method for the analysis of nine pteridines in human serum has been reported. Two analytical columns composed by C18 porous and fused core particles were assayed and the results compared. Fused core particle column allows us adequate separation, in only one run and in 15 min. Acid precipitation step of the proteins and clean-up process with an Isolute ENV+ (hydroxylated polystyrene-divinylbenzene copolymer) cartridge of the serum samples have been optimized. Analytes were determined by fluorimetric detection, exciting at 272 nm and measuring the fluorescence emission at 410 nm for isoxanthopterin, at 465 nm for xanthopterin, and at 445 nm for the analysis of the other pteridines. Detection limits between 0.07 and 0.61 ng mL(-1) were calculated according to Clayton criterium. Intraday precision varied from 1.2 to 5.3 and interday precision between 1.2 and 7.4, both expressed as RSD (%). External standard and standard addition calibrations were compared in the analysis of serum samples. The pteridine amounts in serum (expressed as ng mL(-1) ± confidence interval) were 3.69 ± 1.78; 1.35 ± 0.24; 0.46 ± 0.14; 0.54 ± 0.24; 0.84 ± 0.55; 2.10 ± 0.51 and 0.23 ± 0.11 for XAN, NEO, MON, ISO, BIO and 6HMPT, respectively, using the external standard method. Comparable results were obtained by the standard addition method. It is noticeable that 7BIO was not detected in the healthy serum samples analyzed.

Determination of pteridines in biological samples with an emphasis on their stability.

Pteridines are a group of endogenous heterocyclic compounds whose concentrations in biological fluids may be increased in some disorders, such as infections, autoimmune disorders and cancer. In particular, pteridine concentrations in urine may represent promising noninvasive markers. However, their specificity requires further investigation. Pteridines can occur in three oxidation states with different stability. In order to enable the analysis of the unstable di- and tetra-hydroforms either an oxidation (mainly with iodine) or stabilization by reducing agents is applied. Due to the high polarity of pteridines, many analytical procedures employed ion-pair, ion-exchange or hydrophilic interaction liquid chromatography using mostly fluorescence detection. In the last decade, MS was found to be applicable. The objective of this Review is to show possibilities and different approaches in pteridine analysis in biological samples.

Evaluation of pteridine metabolism in battery workers chronically exposed to lead.

Occupationally-exposed lead affects the neuromuscular junction and might cause disturbances in the locomotor activity. This study was undertaken to evaluate pteridine metabolism, in which neurotransmitters are synthesized in battery workers. Urinary neopterin, biopterin and creatinine were measured using high performance liquid chromatography. Serum neopterin concentrations were detected by enzyme-linked immunoassay. Blood dihydropteridine reductase (DHPR) activities and deltaaminolevulinic acid (delta-ALA) were measured spectrophotometrically. Blood and urinary lead were detected by atomic absorption spectroscopy. Significantly increased blood and urinary lead levels, urinary neopterin, biopterin and delta-ALA were found in workers, while DHPR activities were indifferent compared to control group. Urinary creatinine decreased. This is the first study to demonstrate that increased activity of the pteridine pathway results in the accumulation of the neurotransmitters that may be responsible for the neurological disorders.

Effect of light therapy on biopterin, neopterin and tryptophan in patients with seasonal affective disorder.

The serotonergic system is believed to play a key role in the pathophysiology of seasonal affective disorder (SAD). Tetrahydrobiopterin is an essential cofactor in the hydroxylation of tryptophan and, therefore, in the synthesis of serotonin, while neopterin is known as a marker of cell-mediated immune activity. The present study was designed to measure levels of biopterin, neopterin and tryptophan in plasma of 19 depressed patients with a history of SAD, before and after light therapy as well as in a control group. In the group of patients a significantly lower plasma biopterin and tryptophan level and a higher neopterin level was demonstrated. After light therapy, the level of biopterin increased to that of the controls but lowered again in summer. Neopterin concentrations remained on the same level after light therapy, whereas tryptophan levels increased slightly after light therapy and reached normal values in summer. It is concluded that the vulnerability for a depressive episode is enhanced by lowered levels of biopterin that, however, in SAD becomes symptomatically manifest in the presence of increased immune activity at the same time.

Plasma pteridine concentrations in patients with chronic renal failure.

BACKGROUND: Pteridine metabolism is impaired in the uraemic state. This may affect cardiovascular function and contribute to malnutrition. We wished to clarify further the impact of impaired pteridine metabolism. METHODS: Using the HPLC method, the plasma concentrations of endogenous pteridines were determined in 64 patients with chronic renal failure (33 on intermittent haemodialysis (HD) treatment vs 31 not yet on renal replacement therapy), and in 18 healthy controls. The patients were classified into three groups on the basis of creatinine clearance (Ccr): group (a), Ccr >60 ml/min; group (b), Ccr=10-60 ml/min; group (c), all patients receiving HD. RESULTS: Total neopterin (NP) and biopterin (BP) levels and the NP/BP ratio (a biomarker for macrophage activity) were significantly higher, whereas tetrahydrobiopterin (BH(4))/dihydrobiopterin (BH(2)) ratio (a biomarker for nitric oxide synthase and phenylalanine hydroxylase activities) was significantly lower in group (c) (118.9+/-11.7 ng/ml, 18.8+/-1.2 ng/ml, 6.79+/-0.53, and 0.26+/-0.06) than in healthy subjects (5.17+/-0.29 ng/ml, 2.83+/-0.19 ng/ml, 1.92+/-0.13, and 1.15+/-0.11; P<0.01). These significant differences were also observed between control and group (b) (12.4+/-2.20 ng/ml, 4.48+/-0.36 ng/ml, 2.81+/-0.48, and 0.74+/-0.08; P<0.01). In groups (a) and (b), significant negative correlations were found between Ccr and the total NP level (r=-0.663, P<0.01), the total BP level (r=-0.492, P<0.01), the BH(2) level (r=-0.677, P<0.01), and the NP/BP ratio (r=-0.493, P<0.01). Conversely, significant positive correlations were found between Ccr and the BH(4)/BH(2) ratio (r=0.602, P<0.01). CONCLUSION: The reduction of quinoid-type BH(2) to BH(4) is modified in patients with advanced chronic renal failure, before and after the initiation of regular HD treatment. These metabolic alterations may play a role in the impaired macrophage, endothelial constitutive nitric oxide synthase, or phenylalanine hydroxylase (PH) activities observed in such patients.

Alterations of tetrahydrobiopterin biosynthesis and pteridine levels in mouse tissues during growth and aging.

In the present study, we investigated age-related changes in pteridine levels and enzymatic activity responsible for tetrahydrobiopterin biosynthesis in mouse tissues. Until about 15 weeks after the birth, the remarkable change of tetrahydrobiopterin (BH4) was observed in all tissues tested. Between 20 and 50 weeks after the birth, pteridines levels were almost constant in all of the tissues. Total biopterin levels were decreased and levels of pterin and neopterin were increased in the period exceeding 50 weeks in all of the tissues. Activities of guanosine triphosphate (GTP) cyclohydrolase I, pyrvoyltetrahydropterin synthase, and the production of BH4 were recognized by specific biochemical assays, and we investigated the age-related changes in mouse tissues. The alteration of these enzymatic activities was indicated to be similar to that described in the change of pteridine levels.

Pteridine and nitrite/nitrate formation in experimental septic and traumatic shock.

Bacterial lipopolysaccharides (LPS) induce the activity of guanosine triphosphate (GTP)-cyclohydrolase I (GTP-CHI), the first enzyme in the biosynthesis of tetrahydrobiopterin (H4bip) from GTP in endothelial cells and macrophages. In these and other cells, LPS also acts costimulatory with cytokines, i.e., mainly tumor necrosis factor-alpha (TNF-alpha). H4bip is the cofactor for nitric oxide synthase (NOS). We were interested in comparing the pteridine and nitrate levels in two baboon models: a hyperdynamic sepsis model and a hemorrhagic traumatic shock model. Our results show a similar response of pteridines (H4bip, neopterin) and nitrite/nitrate levels to an immune stimulus. LPS, which peaks rapidly, induces a sustained increase in pteridine levels in septic animals. Since hemorrhagic animals show very little response in terms of cytokine production, it was not possible to measure the induction of neopterin and nitrite/nitrate. This information could aid our understanding of the regulatory mechanisms in various forms of experimental shock.

Increased plasma kynurenine and its relationship to neopterin and tryptophan in Tourette's syndrome.

Fasting plasma levels of tryptophan, kynurenine and the pteridines, neopterin and tetrahydrobiopterin were measured in seven patients with Gilles de la Tourette syndrome (GTS) and 10 healthy controls. Plasma kynurenine was significantly elevated in the GTS patients. The lowest patient value was higher than the highest control value. Values for tryptophan, neopterin and tetrahydrobiopterin were similar in TS patients and controls. However, in TS patients only, there was a significant negative correlation between tryptophan and neopterin and a significant positive correlation between kynurenine and neopterin when controlling for tryptophan. This finding indicates that activation of cellular immune processes is a possible explanation for the rise in plasma kynurenine.

[A case report of mild from of phenylketonuria].

We report a 19-year-old man with mild form of phenylketonuria. The diagnosis was first made when he was examined for the tremor at 19 years of age. He had not received the Guthrie's screening test for phenylketonuria in infancy. His development of speech and walking was almost normal. Action and positional tremor developed at two years of age, and psychomotor deterioration at five years. His intelligence was of borderline, and he entered the special class for the mentally retarded at elementary school and junior high school. His skin and iris were less pigmented than those of Japanese young adults, and his hair was rather reddish. He had mild action tremor. He showed mild mental retardation, and the WAIS was 46 in PIQ, 70 in VIQ and 53 in total IQ. T2-weighted MRI of the brain showed high signal of the deep white matter around the posterior conus of the lateral ventricles. EEG showed paroxysmal abnormalities. Serum aminogram disclosed a marked elevation of phenylalanine. Analyses of pteridine in the serum and urine disclosed a low ratio of neopterine/biopterine. An assay of the dehydropteridine reductase in erythrocytes was normal. These laboratory data indicated that his condition was caused by a deficiency of phenylalanine hydroxylase deficiency.

A yellow component associated with human transthyretin has properties like a pterin derivative, 7,8-dihydropterin-6-carboxaldehyde.

Transthyretin (TTR) in plasma is associated with yellow compounds. Their properties differ, and in the chicken protein a major yellow compound has recently been identified as a carotenoid, lutein, also called xanthophyll. We now show that the major yellow component extracted from human TTR has properties like a pterin derivative, 7,8-dihydropterin-6-carboxyaldehyde (2-amino-4-hydroxy-6-formyl-7,8-dihydropteridine). The human TTR derivative has chromatographic and spectral properties identical to a yellow photochemical degradation product of biopterin and a spectrum like that of the pterin aldehyde.

2,4-diamino-7-hydroxy-pteridines in biological fluids of patients on high-dose methotrexate.

Concentrations of 2,4-diamino-7-hydroxy-pteridines in plasma and cerebrospinal fluid (CSF) are reported for the 0.5-8 g/m2 dose range of methotrexate in children with acute lymphoblastic leukemia or non-Hodgkin's lymphoma. This experiment has revealed that: (1) there is a wide inter-individual but relatively narrow intra-individual variability of the maximal concentrations of 2,4-diamino-7-hydroxy-pteridines in plasma during consecutive methotrexate cycles; (2) the increase in the level of the metabolites in plasma was related to increments of the methotrexate dose, but not above 5 g/m2: this can be explained by a saturable conversion of methotrexate to 2,4-diamino-7-hydroxy-pteridines; (3) significant correlations were found between simultaneous values of 2,4-diamino-7-hydroxy-pteridines in plasma and CSF; (4) the formation of 2,4-diamino-7-hydroxy-pteridines did not depend on the ages of patients receiving the same dose of methotrexate. The presence of these compounds in plasma and CSF in significant amounts creates the potential for a number of competitive interactions with pteridine-dependent metabolism which may open up new possibilities for understanding the metabolic side-effects of methotrexate therapy.

[Unconjugated pteridines and neuromeningeal infections]. / Ptéridines non conjuguées et infections neuro-méningées.

Concentrations of unconjugated pteridines (neopterin, monapterin, biopterin, pterin) were measured in the cerebrospinal fluid (CSF) of 310 patients, using a high performance liquid chromatography (HPCL) method. Our cohort included 209 controls (C), 15 patients with meningism (M), 22 with viral meningitis (VM), 17 with bacterial meningitis (BM), 9 with herpetic meningoencephalitis (HME), 2 with tuberculous meningoencephalitis (TME) and 36 with peripheral systemic infections (PI). These measurements, expressed as nmol/litre, showed a gradation of neopterin concentrations according to the type of infection: 20.1 + 6.5 in group C; 46.9 +/- 29.9 in group PI; 274.3 +/- 231.7 in group VM; 699.2 +/- 711.2 in group BM, 1,101.9 +/- 1,107.9 in group HME and 1,169 +/- 1,171.9 in group TME. There was no such gradation with biopterin. Comparisons of means showed that total concentrations in the pathology groups were very different from those observed in controls and in the neuromeningeal infections of the PI group. There was no correlation between the number of lymphocytes and the concentrations of neopterin or biopterin in the CSF. It is concluded that the concentration of neopterin in the CSF is a sensitive but little specific marker of infection, independent of CSF cellular reaction. Measuring this concentration makes it possible: 1) to evaluate the status of immune defences; 2) to predict that a meningitis will become chronic, and 3) to detect a possible parenchymal participation in a meningeal infection.

2,4-diamino-7-hydroxy-pteridines, a new class of catabolites of methotrexate.

Methotrexate remains a commonly used drug in the chemotherapy of various malignancies. The known catabolites are 7-hydroxy-methotrexate, formed in the liver, and diamino-methyl-pteroic acid formed in the gut. We report for the first time evidence that 2,4-diamino-7-hydroxy-pteridine derivatives are present in the biological fluids of patients on high-dose methotrexate protocols. So far, two major derivatives have been identified as 2,4-diamino-6-hydroxymethyl-7-hydroxy-pteridine and 2,4-diamino-6-methyl-7-hydroxy-pteridine. In regard to the actual knowledge of the catabolism of pteridines, these compounds are presumably formed by intestinal bacteria during enterohepatic circulation of the drug. Their slow clearance from the body raises the question of possible interference of these compounds on pteridine-dependent enzymes, which might explain in part some of the toxic effects of methotrexate.

7-Substituted pterins. A new class of mammalian pteridines.

Three novel pteridines have been isolated from the urine of patients with a new variant of 6-(L-erythro-1',2'-dihydroxypropyl)-5,6,7,8-tetrahydropterin (tetrahydrobiopterin) deficiency, showing hyperphenylalaninemia. From the results of high performance liquid chromatography, oxidative degradation, and gas chromatography-electron impact mass spectrometry, their structures were identified as 7-(D-erythro-1',2',3'-trihydroxypropyl)-pterin (7-neopterin), 7-(L-erythro-1',2'-dihydroxypropyl)-pterin (7-biopterin), and 6-oxo-7-(L-erythro-1',2'-dihydroxypropyl)-pterin (6-oxo-7-biopterin). The ratio of biopterin to 7-biopterin in the patients' urines was 1:1, and after oral loading with tetrahydrobiopterin, 7-biopterin excretion rose parallel to biopterin. This finding suggests that 7-substituted pterins may be formed endogenously by a yet unknown isomerization reaction. The cause of hyperphenylalaninemia is still unclear. The activities of the enzymes involved in tetrahydrobiopterin biosynthesis and regeneration were found to be normal in the patients, and no effect of 7-biopterin on these enzymes was observed in vitro. However, compared with the normal cofactor, tetrahydrobiopterin, the Km values of tetrahydro-7-biopterin for phenylalanine hydroxylase and dihydropteridine reductase are 20 and 5 times higher, respectively.

Inhibition of monocyte luminol-dependent chemiluminescence by tetrahydrobiopterin, and the free radical oxidation of tetrahydrobiopterin, dihydrobiopterin and dihydroneopterin.

Luminol-dependent chemiluminescence of normal human monocytes activated by zymosan is demonstrated to be inhibited by tetrahydrobiopterin in a concentration-dependent manner. The reduced pterins tetrahydrobiopterin, dihydrobiopterin, and dihydroneopterin are all shown to be readily oxidized by the hydroxyl radical. The susceptibility of reduced pterins to free radical attack may explain the inhibition of chemiluminescence observed and an additional role of reduced pterins as free radical scavengers in tissues is considered.