Folates (B9 vitamins) are essential cofactors in one-carbon metabolism. Since C1 transfer reactions are involved in synthesis of nucleic acids, proteins, lipids, and other biomolecules, as well as in ...epigenetic control, folates are vital for all living organisms. This work presents a complete study of a plant DHFR-TS (dihydrofolate reductase-thymidylate synthase) gene family that implements the penultimate step in folate biosynthesis. We demonstrate that one of the DHFR-TS isoforms (DHFR-TS3) operates as an inhibitor of its two homologs, thus regulating DHFR and TS activities and, as a consequence, folate abundance. In addition, a novel function of folate metabolism in plants is proposed, i.e., maintenance of the redox balance by contributing to NADPH production through the reaction catalyzed by methylenetetrahydrofolate dehydrogenase, thus allowing plants to cope with oxidative stress.
•Nivolumab and pembrolizumab levels in cerebrospinal fluid are much lower than in serum.•Validated enzyme-linked immunoassay can quantify those levels up to 2 ng/mL.•The assay is clinically ...applicable for pharmacokinetics in serum and cerebrospinal fluid.
Immunotherapy with monoclonal antibodies targeting the programmed-death-1 (PD-1) receptor has become standard of care for an increasing number of tumor types. Pharmacokinetic studies may help to optimize anti-PD-1 therapy. Therefore, accurate and sensitive determination of antibody concentrations is essential. Here we report an enzyme linked immunosorbent assay (ELISA) capable of measuring nivolumab and pembrolizumab concentrations in serum and cerebrospinal fluid (CSF) with high sensitivity and specificity. The assay was developed and validated based on the specific capture of nivolumab and pembrolizumab by immobilized PD-1, with subsequent enzymatic chemiluminescent detection by anti-IgG4 coupled with horse radish peroxidase (HRP). The lower limit of quantification for serum and CSF was 2 ng/mL for both anti-PD-1 agents. The ELISA method was validated and showed long term sample stability of >1 year. This method is reliable, relatively inexpensive and can be used in serum and CSF from pembrolizumab and nivolumab treated patients.
NAMI-A H(2)Imtrans-RuCl(4)(DMSO)HIm or imidazolium-trans-DMSO-imidazole-tetrachlororuthenate is a novel ruthenium-containing compound that has demonstrated antimetastatic activity in preclinical ...studies. This Phase I study was designed to determine the maximum-tolerated dose (MTD), profile of adverse events, and dose-limiting toxicity of NAMI-A in patients with solid tumors. Furthermore, the ruthenium pharmacokinetics (PK) after NAMI-A administration and preliminary antitumor activity were evaluated.
Adult patients with solid tumors received NAMI-A as an i.v. infusion over 3 h daily for 5 days every 3 weeks. PK of total and unbound ruthenium was determined during the first and second treatment using noncompartmental pharmacokinetic analysis. The total accumulation of ruthenium in WBCs was also quantified.
Twenty-four patients were treated at 12 dose levels (2.4-500 mg/m(2)/day). At 400 mg/m(2)/day, blisters developed on the hands, fingers, and toes. At 500 mg/m(2)/day, blisters persisted from weeks to months and slowly regressed. Although no formal common toxicity criteria (CTC) grade 3 developed, painful blister formation was considered dose limiting. Because the first signs developed at 400 mg/m(2)/day, the advised dose for further testing of NAMI-A was determined to be 300 mg/m(2)/day on this schedule. PK analysis revealed a linear relationship between dose and area under the concentration-time curve (AUC) of total and unbound ruthenium (R(2) = 0.75 and 0.96, respectively) over the whole dose range. Plasma clearance of total ruthenium was 0.17 +/- 0.09 liter/h, and terminal half-life was 50 +/- 19 h. The volume of distribution at steady state of total ruthenium was 10.1 +/- 2.8 liters. The accumulation of ruthenium in WBC was not directly proportional to the increasing total exposure to ruthenium. One patient with pretreated and progressive nonsmall cell lung cancer had stable disease for 21 weeks.
NAMI-A can be administered safely as a 3-h i.v. infusion at a dose of 300 mg/m(2)/day for 5 days, every 3 weeks.
Cancer cells frequently boost nucleotide metabolism (NM) to support their increased proliferation, but the consequences of elevated NM on tumor de-differentiation are mostly unexplored. Here, we ...identified a role for thymidylate synthase (TS), a NM enzyme and established drug target, in cancer cell de-differentiation and investigated its clinical significance in breast cancer (BC). In vitro, TS knockdown increased the population of CD24
differentiated cells, and attenuated migration and sphere-formation. RNA-seq profiling indicated repression of epithelial-to-mesenchymal transition (EMT) signature genes upon TS knockdown, and TS-deficient cells showed an increased ability to invade and metastasize in vivo, consistent with the occurrence of a partial EMT phenotype. Mechanistically, TS enzymatic activity was found essential for maintenance of the EMT/stem-like state by fueling a dihydropyrimidine dehydrogenase-dependent pyrimidine catabolism. In patient tissues, TS levels were found significantly higher in poorly differentiated and in triple negative BC, and strongly correlated with worse prognosis. The present study provides the rationale to study in-depth the role of NM at the crossroads of proliferation and differentiation, and depicts new avenues for the design of novel drug combinations for the treatment of BC.
Nivolumab is an immunotherapeutic monoclonal antibody (mAb) that is used for the treatment of several types of cancer. The evidence on its use during lactation is lacking. Here, we report on a ...39-year-old woman with metastasized melanoma who was treated with 480 mg nivolumab every four weeks during lactation. Breast milk samples were collected over the course of 34 days, including two cycles of nivolumab. The highest measured concentration of nivolumab during the first cycle was 503 ng/mL at day 13. The cumulative relative infant dose (RID) over the first cycle (28 days) was 9.8 %. The highest overall measured nivolumab concentration was 519 ng/mL at day 33, five days after administration of the second nivolumab cycle. Nivolumab seems to accumulate in breast milk over two consecutive cycles, hence the RIDs of consecutive cycles are expected to be higher. To draw further conclusions regarding safety of breastfeeding during nivolumab therapy, more information about the oral bioavailability of nivolumab in newborns, the nivolumab steady-state concentrations in breast milk and its pharmacodynamic effects are needed.
•For the first time nivolumab distribution to breast milk is determined.•The cumulative relative infant dose over the first cycle (28 days) was 9.8 %.•The highest overall measured nivolumab concentration was 519 ng/mL.•Nivolumab seems to accumulate in breast milk over consecutive cycles.
Moderate diagnostic accuracy of MRI and initial cerebrospinal fluid (CSF) cytology analysis results in at least 10%-15% false negative diagnoses of leptomeningeal metastases (LM) of solid tumors, ...thus postponing start of therapy. The aim of this prospective clinical study was to determine the diagnostic value of epithelial cell adhesion molecule (EpCAM)-based flow cytometry versus cytology in CSF for the diagnosis of LM in patients with epithelial tumors.
Patients with a clinical suspicion of LM but a negative or inconclusive MRI in whom a diagnostic lumbar puncture has to be performed were included. At least 5 mL of CSF for cytology, 5 mL for flow cytometry, 2 mL for cell count and biochemistry, and 8 mL whole blood samples for circulating tumor cells measurements and biochemistry were drawn. Tumor cells in CSF and whole blood were detected by multiparameter flow cytometry using EpCAM antibody.
In total 29 eligible patients were enrolled in the study. Thirteen patients were ultimately diagnosed with LM. The flow cytometry assay showed 100% sensitivity and 100% specificity for diagnosing LM, while sensitivity of CSF cytology was only 61.5%. Cell count or biochemical parameters in CSF were abnormal in 100% of patients with LM.
Our results suggest that the EpCAM-based flow cytometry assay is superior to CSF cytology for the diagnosis of LM in patients with an epithelial tumor, a clinical suspicion of LM, and a nonconclusive MRI. Confirmation of these data is needed in a larger dataset to recommend dual CSF diagnostics for LM.
NCT01713699.
The diagnosis of leptomeningeal metastases (LM) of solid tumors is complicated due to low sensitivities of both magnetic resonance imaging (MRI) and cytology. MRI has a sensitivity of 76% for the ...diagnosis of LM and cerebrospinal fluid (CSF) cytology has a sensitivity of 44–67% at first lumbar puncture which increases to 84–91% upon second CSF sampling. Epithelial cell adhesion molecule (EpCAM) is expressed by solid tumors of epithelial origin like non-small-cell lung cancer, breast cancer or ovarium cancer. Recently, a CELLSEARCH
®
assay and flow cytometry laboratory techniques have been developed to detect circulating tumor cells (CTCs) of epithelial origin in CSF. These laboratory techniques are based on capture antibodies labelled with different fluorescent tags against EpCAM. In this review, we provide an overview of the available laboratory techniques and diagnostic accuracy for tumor cell detection in CSF. The reported sensitivities of the EpCAM-based CTC assays for the diagnosis of LM across the different studies are highly promising and vary between 76 and 100%. An overview of the different EpCAM-based techniques for the enumeration of CTCs in the CSF is given and a comparison is made with CSF cytology for the diagnoses of LM from epithelial tumors.
Imatinib mesylate (signal transduction inhibitor 571, Gleevec) is a potent and selective tyrosine kinase inhibitor, which was shown to effectively inhibit platelet-derived growth factor-induced ...glioblastoma cell growth preclinically. However, in patients, a limited penetration of imatinib into the brain has been reported. Imatinib is transported in vitro and in vivo by P-glycoprotein (P-gp; ABCB1), which thereby limits its distribution into the brain in mice. Previously, imatinib was shown to potently inhibit human breast cancer resistance protein (BCRP; ABCG2). Here, we show that imatinib is efficiently transported by mouse Bcrp1 in transfected Madin-Darby canine kidney strain II (MDCKII) monolayers. Furthermore, we show that the clearance of i.v. imatinib is significantly decreased 1.6-fold in Bcrp1 knockout mice compared with wild-type mice. At t = 2 hours, the brain penetration of i.v. imatinib was significantly 2.5-fold increased in Bcrp1 knockout mice compared with control mice. We tested the hypothesis that P-gp and BCRP inhibitors, such as elacridar and pantoprazole, improve the brain penetration of imatinib. Firstly, we showed in vitro that pantoprazole and elacridar inhibit the Bcrp1-mediated transport of imatinib in MDCKII-Bcrp1 cells. Secondly, we showed that co-administration of pantoprazole or elacridar significantly reduced the clearance of i.v. imatinib in wild-type mice by respectively 1.7-fold and 1.5-fold. Finally, in wild-type mice treated with pantoprazole or elacridar, the brain penetration of i.v. imatinib significantly increased 1.8-fold and 4.2-fold, respectively. Moreover, the brain penetration of p.o. imatinib increased 5.2-fold when pantoprazole was co-administered in wild-type mice. Our results suggest that co-administration of BCRP and P-gp inhibitors may improve delivery of imatinib to malignant gliomas.
Purpose
Capecitabine is an oral pre-pro-drug of the anti-cancer drug 5-fluorouracil (5-FU). The biological activity of the 5-FU degrading enzyme, dihydropyrimidine dehydrogenase (DPD), and the target ...enzyme thymidylate synthase (TS), are subject to circadian rhythmicity in healthy volunteers. The aim of this study was to determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), safety, pharmacokinetics (PK) and pharmacodynamics (PD) of capecitabine therapy adapted to this circadian rhythm (chronomodulated therapy).
Methods
Patients aged ≥18 years with advanced solid tumours potentially benefitting from capecitabine therapy were enrolled. A classical dose escalation 3 + 3 design was applied. Capecitabine was administered daily without interruptions. The daily dose was divided in morning and evening doses that were administered at 9:00 h and 24:00 h, respectively. The ratio of the morning to the evening dose was 3:5 (morning: evening). PK and PD were examined on treatment days 7 and 8.
Results
A total of 25 patients were enrolled. The MTD of continuous chronomodulated capecitabine therapy was established at 750/1250 mg/m
2
/day, and was generally well tolerated. Circadian rhythmicity in the plasma PK of capecitabine, dFCR, dFUR and 5-FU was not demonstrated. TS activity was induced and DPD activity demonstrated circadian rhythmicity during capecitabine treatment.
Conclusion
The MTD of continuous chronomodulated capecitabine treatment allows for a 20% higher dose intensity compared to the approved regimen (1250 mg/m
2
bi-daily on day 1–14 of every 21-day cycle). Chronomodulated treatment with capecitabine is promising and could lead to improved tolerability and efficacy of capecitabine.
PARP inhibitors are currently evaluated in combination with radiotherapy and/or chemotherapy. As sensitizers, PARP inhibitors are active at very low concentrations therefore requiring highly ...sensitive pharmacodynamic (PD) assays. Current clinical PD-assays partly fail to provide such sensitivities. The aim of our study was to enable sensitive PD evaluation of PARP inhibitors for clinical sensitizer development.
PBMCs of healthy individuals and of olaparib and radiotherapy treated lung cancer patients were collected for ELISA-based PD-assays.
PAR-signal amplification by ex vivo irradiation enabled an extended quantification range for PARP inhibitory activities after ex vivo treatment with inhibitors. This “radiation-enhanced-PAR” (REP) assay provided accurate IC50 values thereby also revealing differences among healthy individuals. Implemented in clinical radiotherapy combination Phase I trials, the REP-assay showed sensitive detection of PARP inhibition in patients treated with olaparib and establishes strong PARP inhibitory activities at low daily doses.
Combination trials of radiotherapy and novel targeted agent(s) often require different and more sensitive PD assessments than in the monotherapy setting. This study shows the benefit and relevance of sensitive and adapted PD-assays for such combination purposes and provides proof of clinically relevant cellular PARP inhibitory activities at low daily olaparib doses.
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