A phase I/II study of nintedanib and capecitabine for refractory metastatic colorectal cancer

BACKGROUND

Nintedanib is a tyrosine kinase inhibitor with efficacy in bevacizumab-resistant colorectal cancer models. This phase I/II study evaluated the recommended phase II dose and efficacy of nintedanib and capecitabine in refractory metastatic colorectal cancer.

METHODS

Key eligibility criteria included refractory metastatic colorectal cancer and ECOG performance status of 1 or lower. The primary endpoint was 18-week progression-free survival (PFS). A 1-sided binomial test (at α = .1) compared the observed 18-week PFS with a historic control of .25.

RESULTS

Forty-two patients were enrolled, including 39 at the recommended phase II dose. The recommended phase II dose was established to be nintedanib 200 mg by mouth twice daily and capecitabine 1000 mg/m2 by mouth twice daily. The protocol was evaluated for efficacy in 36 patients. The 18-week PFS was 42% (15/36 patients; P = .0209). Median PFS was 3.4 mo. Median overall survival was 8.9 mo. Sixteen (44%) patients experienced a grade 3/4 adverse event, most commonly fatigue (8%), palmoplantar erythrodysesthesia (8%), aspartate aminotransferase elevation (6%), asthenia (6%), pulmonary embolus (6%), and dehydration (6%). Osteopontin levels at cycle 1, day 1 and cycle 3, day 1 as well as ΔCCL2 levels correlated to disease control at 18 weeks.

CONCLUSIONS

The combination of nintedanib and capecitabine is well tolerated. Clinical efficacy appears to be superior to regorafenib or tipiracil hydrochloride monotherapy. Further investigation of similar combinations is warranted.

CLINICALTRIALS.GOV IDENTIFIER

NCT02393755.

Identification of unique molecular heterogeneity of human CD79, the signaling component of the human B cell antigen receptor (BCR), and synergistic potentiation of the CD79-targeted therapy of B cell tumors by co-targeting of CD79a and CD79b

We identified unique molecular heterogeneity of CD79 of human B cell antigen receptor (BCR) that may open a new approach to the ongoing CD79b-targeted therapy of B cell tumors. The primary purpose of the present study is to gain new information valuable for the enhanced CD79-targeted therapy. The molecular heterogeneity of CD79 was identified by sequential immunoprecipitation of BCR by use of anti-CD79b monoclonal antibody (mAb) SN8 and anti-CD79a mAb SN8b. SN8 is the antibody component of polatuzumab vedotin, an anti-CD79b antibody drug conjugate, that has been widely used for therapy of diffuse large B-cell lymphoma (DLBCL). The sequential immunoprecipitation shows that anti-CD79b mAb will be able to react only with a subgroup of CD79 molecules while anti-CD79a mAb will react with another subgroup of CD79 molecules; CD79 is a disulfide-linked heterodimer of CD79a and CD79b. Therapeutic study of SCID mice bearing human B-cell tumor shows synergistic potentiation by co-targeting CD79b and CD79a. Furthermore, simultaneous targeting of PD-1 strongly potentiates CD79a/CD79b-targeted therapy of B cell tumors. Flow cytometry analyses of CD79a/CD79b on malignant B cells of patients may provide a method for selection of the candidate patients for the CD79a/CD79b dual targeting therapy.

Development and validation of an LC-MS/MS method to measure the BRAF inhibitors dabrafenib and encorafenib quantitatively and four major metabolites semi-quantitatively in human plasma

This article describes the development and validation of a liquid-chromatography coupled with tandem mass spectrometry (LC-MS/MS) assay for the simultaneous quantitation of the BRAF inhibitors dabrafenib and encorafenib, and semi-quantitation of their major metabolites (i.e., carboxy-dabrafenib, desmethyl-dabrafenib, hydroxy-dabrafenib, M42.5A) in human plasma. Analytes were extracted from human plasma by protein precipitation, followed by reversed phase high-performance liquid chromatography. Analyte detection was performed using tandem mass spectrometry with heated electrospray ionization operating in positive ion mode. The assay was validated in accordance with the current U.S. Food and Drug Administration Guidance on Bioanalytical Method Validation. Results showed that measurements were both accurate (94.6-112.0 %) and precise (within-run: 1.9-3.4 %; between-run: 1.7-12.0 %) spanning a concentration range of 5 to 2000 ng/mL for dabrafenib and 10 to 4000 ng/mL for encorafenib. Recoveries for these analytes were consistent with mean values ranging from 85.6 % to 90.9 %. The mean internal standard-normalized matrix factors for each drug ranged between 0.87 and 0.98 and were found to be precise (% RSD <6.4 %). Dabrafenib and encorafenib were stable in the final extract and in human plasma held under various storage conditions. The metabolites also passed the validation criteria for precision and selectivity. Finally, the clinical applicability of the assay was confirmed by (semi-)quantitation of all six analytes in plasma samples from cancer patients receiving standard-of-care treatment with dabrafenib and encorafenib. Reproducibility of the measured analyte concentrations in study samples was confirmed successfully by incurred sample reanalysis. In conclusion, this sensitive LC-MS/MS assay has been validated successfully and is suitable for therapeutic drug monitoring of dabrafenib and encorafenib and clinical pharmacokinetic studies with these BRAF inhibitors.

Population Pharmacokinetics and Pharmacodynamics of Carfilzomib in Combination with Rituximab, Ifosfamide, Carboplatin, and Etoposide in Adult Patients with Relapsed/Refractory Diffuse Large B Cell Lymphoma

BACKGROUND

In patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), salvage chemotherapy regimens (e.g., rituximab, ifosfamide, carboplatin, and etoposide, R-ICE) yield poor outcomes. Carfilzomib, an irreversible proteasome inhibitor, can overcome acquired rituximab-chemotherapy resistance and, when combined with R-ICE, improves outcomes in patients with R/R DLBCL.

OBJECTIVE

This analysis aimed to develop a population pharmacokinetic/pharmacodynamic (PK/PD) model for carfilzomib in R/R DLBCL patients.

PATIENTS AND METHODS

In a single-center, open-label, prospective phase 1 study, patients received carfilzomib (10, 15, or 20 mg/m2) on days 1, 2, 8, and 9, and standard doses of R-ICE on days 3-6 every 21 days (maximum of three cycles). Carfilzomib plasma concentrations up to 24 h postinfusion were measured by liquid chromatography coupled with tandem mass spectrometry. Proteasome activity (PD biomarker) in peripheral blood mononuclear cells was assessed on days 1-2 with sparse sampling. PK/PD models were developed using NONMEM v7.4.1 interfaced with Finch Studio v1.1.0 and PsN v4.7.0. Model selection was guided by objective function value, goodness-of-fit, and visual predictive checks. Stepwise covariate modeling was used for covariate selection.

RESULTS

Twenty-eight patients were enrolled in the PK/PD analysis, from whom 217 PK samples and 127 PD samples were included. Carfilzomib PK was best described by a two-compartment model with linear disposition (typical total clearance of 133 L/h). Proteasome activity was best characterized using a turnover model with irreversible inactivation. All parameters were estimated with good precision. No statistically significant covariates were identified.

CONCLUSIONS

A validated population-based PK/PD model of carfilzomib was developed successfully. Further research is needed to identify sources of variability in response to treatment with carfilzomib in combination with R-ICE.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier number NCT01959698.

Development and Validation of a Quantitative LC-MS/MS Method for CDK4/6 Inhibitors Palbociclib, Ribociclib, Abemaciclib, and Abemaciclib-M2 in Human Plasma

BACKGROUND

The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, palbociclib, ribociclib, and abemaciclib, are standard-of-care agents for patients with hormone receptor-positive human epidermal growth factor receptor 2-negative metastatic breast cancer. In support of therapeutic drug monitoring and clinical pharmacokinetic studies, a liquid chromatography coupled with tandem mass spectrometry assay for the simultaneous quantitation of CDK4/6 inhibitors and the major active metabolite M2 of abemaciclib in human plasma has been developed.

METHODS

Analytes were extracted from 50 μL of human plasma by precipitating proteins with methanol and then collecting the supernatant. Reversed-phase high-performance liquid chromatography was performed for analyte separation using a biphasic gradient at a flow rate of 0.25-0.5 mL/min. The total run time was 9.5 minutes. The analytes were detected using MS/MS with electrospray ionization operating in positive ion mode.

RESULTS

Validation according to the US Food and Drug Administration's guidance showed that the new assay produced accurate (94.7%-107%) and precise (within-run: 1.2%-8.2%; between-run: 0.6%-7.5%) measurements of all analytes over a concentration range of 5-2000 ng/mL. Overall, analyte recoveries were consistent (mean values: 110%-129%). The analytes were also stable in human plasma and the final extract under various storage conditions. Finally, the clinical applicability of the assay was confirmed by quantitation of all analytes in plasma samples obtained from patients treated with CDK4/6 inhibitors. Reproducibility of the measured analyte concentrations in study samples was confirmed successfully by incurred sample reanalysis.

CONCLUSIONS

A sensitive liquid chromatography coupled with tandem mass spectrometry method to measure CDK4/6 inhibitors was developed and validated according to the Food and Drug Administration criteria. Quantitation of all analytes in clinical plasma samples confirmed that the assay is suitable for therapeutic drug monitoring and clinical pharmacokinetic studies of CDK4/6 inhibitors.

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

Characterization and Synthesis of Eudistidine C, a Bioactive Marine Alkaloid with an Intriguing Molecular Scaffold

An extract of Eudistoma sp. provided eudistidine C (1), a heterocyclic alkaloid with a novel molecular framework. Eudistidine C (1) is a racemic natural product composed of a tetracyclic core structure further elaborated with a p-methoxyphenyl group and a phenol-substituted aminoimidazole moiety. This compound presented significant structure elucidation challenges due to the large number of heteroatoms and fully substituted carbons. These issues were mitigated by application of a new NMR pulse sequence (LR-HSQMBC) optimized to detect four- and five-bond heteronuclear correlations and the use of computer-assisted structure elucidation software. Synthesis of eudistidine C (1) was accomplished in high yield by treating eudistidine A (2) with 4(2-amino-1H-imidazol-5-yl)phenol (4) in DMSO. Synthesis of eudistidine C (1) confirmed the proposed structure and provided material for further biological characterization. Treatment of 2 with various nitrogen heterocycles and electron-rich arenes provided a series of analogues (5-10) of eudistidine C. Chiral-phase HPLC resolution of epimeric eudistidine C provided (+)-(R)-eudistidine C (1a) and (-)-(S)-eudistidine C (1b). The absolute configuration of these enantiomers was assigned by ECD analysis. (-)-(S)-Eudistidine C (1b) modestly inhibited interaction between the protein binding domains of HIF-1α and p300. Compounds 1, 2, and 6-10 exhibited significant antimalarial activity against Plasmodium falciparum.

Sequence-Specific Pharmacokinetic and Pharmacodynamic Phase I/Ib Study of Olaparib Tablets and Carboplatin in Women's Cancer

Purpose: Our preclinical studies showed that the PARP inhibitor, olaparib, prior to carboplatin attenuated carboplatin cytotoxicity. We evaluated sequence-specific pharmacokinetic and pharmacodynamic effects, safety, and activity of the combination.Experimental Design: Eligible patients had metastatic or recurrent women's cancer. Olaparib tablets were introduced (100 or 200 mg twice daily, days 1-7) in a 3 + 3 dose escalation with carboplatin AUC4 or 5 every 21 days, up to eight cycles, followed by olaparib 300 mg twice daily maintenance. Patients were randomly assigned to starting schedule: cohort A (olaparib days 1-7, carboplatin on day 8) or B (carboplatin on day 1, olaparib days 2-8) during cycle 1. Patients received the reversed scheme in cycle 2. Blood was collected for olaparib pharmacokinetics, platinum-DNA adducts, comet assay, and PAR concentrations. The primary objectives were to examine schedule-dependent effects on olaparib pharmacokinetics and platinum-DNA adducts.Results: A total of 77 (60 ovarian, 14 breast, and 3 uterine cancer) patients were treated. Dose-limiting toxicity was thrombocytopenia and neutropenia, defining olaparib 200 mg twice daily + carboplatin AUC4 as the MTD. Olaparib clearance was increased approximately 50% when carboplatin was given 24 hours before olaparib. In vitro experiments demonstrated carboplatin preexposure increased olaparib clearance due to intracellular olaparib uptake. Quantities of platinum-DNA adducts were not different as a function of the order of drug administration. Responses included 2 CRs and 31 PRs (46%) with a higher RR in BRCA mutation carriers compared with nonmutation carriers (68% vs. 19%).Conclusions: Tablet olaparib with carboplatin is a safe and active combination. Carboplatin preexposure causes intracellular olaparib accumulation reducing bioavailable olaparib, suggesting carboplatin should be administered prior to olaparib. Clin Cancer Res; 23(6); 1397-406. ©2016 AACR.

Screening and Biological Effects of Marine Pyrroloiminoquinone Alkaloids: Potential Inhibitors of the HIF-1α/p300 Interaction

Inhibition of the hypoxia-inducible factor 1α (HIF-1α) pathway by disrupting its association with the transcriptional coactivator p300 inhibits angiogenesis and tumor development. Development of HIF-1α/p300 inhibitors has been hampered by preclinical toxicity; therefore, we aimed to identify novel HIF-1α/p300 inhibitors. Using a cell-free assay designed to test compounds that block HIF-1α/p300 binding, 170 298 crude natural product extracts and prefractionated samples were screened, identifying 25 active extracts. One of these extracts, originating from the marine sponge Latrunculia sp., afforded six pyrroloiminoquinone alkaloids that were identified as positive hits (IC50 values: 1-35 μM). Luciferase assays confirmed inhibition of HIF-1α transcriptional activity by discorhabdin B (1) and its dimer (2), 3-dihydrodiscorhabdin C (3), makaluvamine F (5), discorhabdin H (8), discorhabdin L (9), and discorhabdin W (11) in HCT 116 colon cancer cells (0.1-10 μM, p < 0.05). Except for 11, all of these compounds also reduced HIF-1α transcriptional activity in LNCaP prostate cancer cells (0.1-10 μM, p < 0.05). These effects occurred at noncytotoxic concentrations (<50% cell death) under hypoxic conditions. At the downstream HIF-1α target level, compound 8 (0.5 μM) significantly decreased VEGF secretion in LNCaP cells (p < 0.05). In COLO 205 colon cancer cells no activity was shown in the luciferase or cytotoxicity assays. Pyrroloiminoquinone alkaloids are a novel class of HIF-1α inhibitors, which interrupt the protein-protein interaction between HIF-1α and p300 and consequently reduce HIF-related transcription.

UGT genotyping in belinostat dosing

Certain genetic polymorphisms of UDP glucuronosyltransferase 1 family, polypeptide A1 (UGT1A1) can reduce gene expression (*28, *60, *93) or activity (*6), thereby altering the pharmacokinetics, pharmacodynamics, and the risk of toxicities of UGT1A1 substrates, of which irinotecan is a widely-described example. This review presents an overview of the clinical effects of UGT1A1 polymorphisms on the pharmacology of UGT1A1 substrates, with a special focus on the novel histone deacetylase inhibitor belinostat. Belinostat, approved for the treatment of peripheral T-cell lymphoma, is primarily glucuronidated by UGT1A1. Recent preclinical and clinical data showed that UGT1A1*28 was associated with reduced glucuronidation in human liver microsomes, while in a retrospective analysis of a Phase I trial with patients receiving belinostat UGT1A1*60 was predominantly associated with increased belinostat plasma concentrations. Furthermore, both UGT1A1*28 and *60 variants were associated with increased incidence of thrombocytopenia and neutropenia. Using population pharmacokinetic analysis a 33% dose reduction has been proposed for patients carrying UGT1A1 variant alleles. Clinical effects of this genotype-based dosing recommendation is currently prospectively being investigated. Overall, the data suggest that UGT1A1 genotyping is useful for improving belinostat therapy.

UGT1A1 genotype-dependent dose adjustment of belinostat in patients with advanced cancers using population pharmacokinetic modeling and simulation

Belinostat is a second-generation zinc-binding histone deacetylase inhibitor that is approved for peripheral T-cell lymphoma and is currently being studied in small cell lung cancer and other advanced carcinomas as a 48-hour continuous intravenous infusion. Belinostat is predominantly metabolized by UGT1A1, which is polymorphic. Preliminary analyses revealed a difference in belinostat clearance based on UGT1A1 genotype. A 2-compartment population pharmacokinetic (PK) model was developed and validated that incorporated the UGT1A1 genotype, albumin, and creatinine clearance on the clearance parameter; body weight was a significant covariate on volume. Simulated doses of 600 and 400 mg/m(2) /24 h given to patients considered extensive or impaired metabolizers, respectively, provided equivalent AUCs. This model and subsequent simulations supported additional PK/toxicity and pharmacogenomics/toxicity analyses to suggest a UGT1A1 genotype-based dose adjustment to normalize belinostat exposure and allow for more tolerable therapy. In addition, global protein lysine acetylation was modeled with PK and demonstrated a reversible belinostat exposure/response relationship, consistent with previous reports.

Effects of UGT1A1 genotype on the pharmacokinetics, pharmacodynamics, and toxicities of belinostat administered by 48-hour continuous infusion in patients with cancer

The histone deacetylase inhibitor belinostat is eliminated through glucuronidation by UGT1A1. Polymorphisms that reduce UGT1A1 function could result in increased belinostat exposure and toxicities. We wanted to determine which single-nucleotide polymorphisms alter belinostat exposure and toxicity. In a phase 1 trial (belinostat over 48 hours in combination with cisplatin and etoposide), belinostat (400, 500, 600, or 800 mg/m(2) /24 h, 48-hour continuous infusion) was administered to patients with cancer in combination with cisplatin and etoposide (n = 25). Patients were genotyped for UGT1A1 variants associated with reduced function: UGT1A1*6, UGT1A1*28, and UGT1A1*60. End points were associations between UGT1A1 genotype and belinostat pharmacokinetics (PK), toxicities, and global protein lysine acetylation (AcK). Belinostat AUC was increased (P = .003), and t1/2 increased (P = .0009) in UGT1A1*28 and UGT1A1*60 carriers who received more than 400 mg/m(2) /24 h. The incidence of grades 3-4 thrombocytopenia (P = .0081) was associated with UGT1A1 polymorphisms. The US Food and Drug Administration-approved package insert recommends dose adjustment of belinostat for UGT1A1*28. However, our data suggest dose adjustment is also necessary for UGT1A1*60. UGT1A1 polymorphisms were associated with increased systemic belinostat exposure, increased AcK, and increased incidence of toxicities, particularly at doses > 400 mg/m(2) /24 h.

Structural Elucidation and Synthesis of Eudistidine A: An Unusual Polycyclic Marine Alkaloid that Blocks Interaction of the Protein Binding Domains of p300 and HIF-1α

Low oxygen environments are a hallmark of solid tumors, and transcription of many hypoxia-responsive genes needed for survival under these conditions is regulated by the transcription factor HIF-1 (hypoxia-inducible factor 1). Activation of HIF-1 requires binding of its α-subunit (HIF-1α) to the transcriptional coactivator protein p300. Inhibition of the p300/HIF-1α interaction can suppress HIF-1 activity. A screen for inhibitors of the protein binding domains of p300 (CH1) and HIF-1α (C-TAD) identified an extract of the marine ascidian Eudistoma sp. as active. Novel heterocyclic alkaloids eudistidines A (1) and B (2) were isolated from the extract, and their structures assigned by spectroscopic analyses. They contain an unprecedented tetracyclic core composed of two pyrimidine rings fused with an imidazole ring. Eudistidine A (1) was synthesized in a concise four-step sequence featuring a condensation/cyclization reaction cascade between 4-(2-aminophenyl)pyrimidin-2-amine (3) and 4-methoxy-phenylglyoxal (4), while eudistidine B (2) was synthesized in a similar fashion with glyoxylic acid (5) in place of 4. Naturally occurring eudistidine A (1) effectively inhibited CH1/C-TAD binding with an IC50 of 75 μM, and synthetic 1 had similar activity. The eudistidine A (1) scaffold, which can be synthesized in a concise, scalable manner, may provide potential therapeutic lead compounds or molecular probes to study p300/HIF-1α interactions and the role these proteins play in tumor response to low oxygen conditions. The unique structural scaffolds and functional group arrays often found in natural products make these secondary metabolites a rich source of new compounds that can disrupt critical protein-protein binding events.

The in-vitro effect of complementary and alternative medicines on cytochrome P450 2C9 activity

OBJECTIVES

The aim of this study is to establish the inhibitory effects of 14 commonly used complementary and alternative medicines (CAM) on the metabolism of cytochrome P450 2C9 (CYP2C9) substrates 7-methoxy-4-trifluoromethyl coumarine (MFC) and tolbutamide. CYP2C9 is important for the metabolism of numerous drugs and inhibition of this enzyme by CAM could result in elevated plasma levels of drugs that are CYP2C9 substrates. Especially for anticancer drugs, which have a narrow therapeutic window, small changes in their plasma levels could easily result in clinically relevant toxicities.

METHODS

The effects of CAM on CYP2C9-mediated metabolism of MFC were assessed in Supersomes, using the fluorometric CYP2C9 inhibition assay. In human liver microsomes (HLM) the inhibition of CYP2C9-mediated metabolism of tolbutamide was determined, using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS).

KEY FINDINGS

The results indicated milk thistle as the most potent CYP2C9 inhibitor. For milk thistle, silybin (main constituent of milk thistle) was mainly responsible for the inhibition of CY2C9.

CONCLUSIONS

Milk thistle and green tea were confirmed as potent inhibitors of CYP2C9-mediated metabolism of multiple substrates in vitro. Clinical studies with milk thistle are recommended to establish the clinical relevance of the demonstrated CYP2C9 inhibition.

Potential novel role of bevacizumab in glioblastoma and cervical cancer

The VEGF-A binding monoclonal antibody bevacizumab is a widely prescribed angiogenesis inhibitor and indicated for many types of cancer. As shown by three randomized phase 3 trials recently published in the New England Journal of Medicine, novel indications for this drug are still being explored. In the RTOG 0825 and AVAglio trials the effect of bevacizumab addition to standard therapy in newly diagnosed glioblastoma (radiotherapy plus temozolomide) was investigated, while in GOG 240 the combination of platinum-based chemotherapy plus bevacizumab was explored in advanced cervical cancer. In RTOG 0825, addition of bevacizumab to standard therapy did not result in survival benefit, and moreover, quality of life was more deteriorated in the bevacizumab arm. In AVAglio, however, progression-free survival (PFS) was significantly increased in the bevacizumab group and these patients also experienced a longer deterioration-free survival. These conflicting results do not fully support the incorporation of bevacizumab in the first-line treatment of glioblastoma. In contrast, in GOG 240 the bevacizumab group (including paclitaxel plus topotecan or paclitaxel) experienced a significant longer PFS and overall survival, and quality of life was not negatively affected in these patients. Thus, these results favor the use of bevacizumab in the treatment of advanced cervical cancer.

The effect of Echinacea purpurea on the pharmacokinetics of docetaxel

AIMS

The herbal medicine Echinacea purpurea (E. purpurea) has been shown to induce cytochrome P450 3A4 (CYP3A4) both in vitro and in humans. This study explored whether E. purpurea affects the pharmacokinetics of the CYP3A4 substrate docetaxel in cancer patients.

METHODS

Ten evaluable cancer patients received docetaxel (135 mg, 60 min IV infusion) before intake of a commercially available E. purpurea extract (20 oral drops three times daily) and 3 weeks later after a 14 day supplementation period with E. purpurea. In both cycles, pharmacokinetic parameters of docetaxel were determined.

RESULTS

Before and after supplementation with E. purpurea, the mean area under the plasma concentration-time curve of docetaxel was 3278 ± 1086 and 3480 ± 1285 ng ml(-1) h, respectively. This result was statistically not significant. Nonsignificant alterations were also observed for the elimination half-life (from 30.8 ± 19.7 to 25.6 ± 5.9 h, P = 0.56) and maximum plasma concentration of docetaxel (from 2224 ± 609 to 2097 ± 925 ng ml(-1) , P = 0.30).

CONCLUSIONS

The multiple treatment of E. purpurea did not significantly alter the pharmacokinetics of docetaxel in this study. The applied E. purpurea product at the recommended dose may be combined safely with docetaxel in cancer patients.

Relevance of in vitro and clinical data for predicting CYP3A4-mediated herb-drug interactions in cancer patients

The use of complementary and alternative medicines (CAM) by cancer patients is increasing. Concomitant use of CAM and anticancer drugs could lead to serious safety issues in patients. CAM have the potential to cause pharmacokinetic interactions with anticancer drugs, leading to either increased or decreased plasma levels of anticancer drugs. This could result in unexpected toxicities or a reduced efficacy. Significant pharmacokinetic interactions have already been shown between St. John's Wort (SJW) and the anticancer drugs imatinib and irinotecan. Most pharmacokinetic CAM-drug interactions, involve drug metabolizing cytochrome P450 (CYP) enzymes, in particular CYP3A4. The effect of CAM on CYP3A4 activity and expression can be assessed in vitro. However, no data have been reported yet regarding the relevance of these in vitro data for the prediction of CAM-anticancer drug interactions in clinical practice. To address this issue, a literature research was performed to evaluate the relevance of in vitro data to predict clinical effects of CAM frequently used by cancer patients: SJW, milk thistle, garlic and Panax ginseng (P. ginseng). Furthermore, in clinical studies the sensitive CYP3A4 substrate probe midazolam is often used to determine pharmacokinetic interactions. Results of these clinical studies with midazolam are used to predict pharmacokinetic interactions with other drugs metabolized by CYP3A4. Therefore, this review also explored whether clinical trials with midazolam are useful to predict clinical pharmacokinetic CAM-anticancer drug interactions. In vitro data of SJW have shown CYP3A4 inhibition after short-term exposure and induction after long-term exposure. In clinical studies using midazolam or anticancer drugs (irinotecan and imatinib) as known CYP3A4 substrates in combination with SJW, decreased plasma levels of these drugs were observed, which was expected as a consequence of CYP3A4 induction. For garlic, no effect on CYP3A4 has been shown in vitro and also in clinical studies garlic did not affect the pharmacokinetics of both midazolam and docetaxel. Milk thistle and P. ginseng predominantly showed CYP3A4 inhibition in vitro. However, in clinical studies these CAM did not cause significant pharmacokinetic interactions with midazolam, irinotecan, docetaxel and imatinib. Most likely, factors as poor pharmaceutical availability, solubility and bioavailability contribute to the lack of significant clinical interactions. In conclusion, in vitro data are useful as a first indication for potential pharmacokinetic drug interactions with CAM. However, the discrepancies between in vitro and clinical results for milk thistle and P. ginseng show that clinical studies are required for confirmation of potential interactions. At last, midazolam as a model substrate for CYP3A4, has convincingly shown to correctly predict clinical interactions between CAM and anticancer drugs.

The mania-like exploratory profile in genetic dopamine transporter mouse models is diminished in a familiar environment and reinstated by subthreshold psychostimulant administration

Bipolar Disorder (BD) is a neuropsychiatric disorder characterized by symptoms ranging from a hyperactive manic state to depression, with periods of relative stability, known as euthymia, in between. Although prognosis for BD sufferers remains poor, treatment development has been restricted due to a paucity of validated animal models. Moreover, most models focus on the manic state of BD with little done to characterize the longitudinal behavior of these models. We recently presented two dopamine transporter (DAT) mouse models of BD mania: genetic (DAT knockdown; KD, mice) and pharmacological (the selective DAT inhibitor GBR 12909). These models exhibit an exploratory profile consistent with the quantified exploratory profile of manic BD patients observed in the cross-species translational test, the Behavioral Pattern Monitor (BPM). To further explore the suitability of these models, we examined the effects of reduced DAT function on the behavior of mice tested after familiarization to the BPM environment. Testing with 16mg/kg GBR 12909 in familiarized mice resulted in a consistent mania-like profile. In contrast, the mania-like profile of DAT KD mice disappears in a familiar environment, with partial reinstatement elicited by the introduction of novelty. In addition, we found that a subthreshold dose of GBR 12909 (9mg/kg) reinstated the mania-like profile in DAT KD mice without affecting wildtype behavior. Thus, the mania-like exploratory profile of DAT KD mice is reduced in a familiar environment, partially reinstated with novelty, but is fully restored when administered a stimulant that is ineffective in wildtype mice. These mice may provide a model of BD from mania to euthymia and back again with stimulant treatment. Acute blockade of the DAT by GBR 12909 however, may provide a consistent model for BD mania.

[Dexrazoxane in anthracycline induced cardiotoxicity and extravasation]

Cardiotoxicity and extravasation injuries are extremely serious complications of anthracycline use. Both complications are probably caused by oxidative stress. Dexrazoxane has been approved as a cardioprotective agent and as an antidote in extravasation of anthracyclines. Randomized clinical trials have shown that dexrazoxane is the only cardioprotective agent proven to be effective in the treatment of anthracycline-induced cardiotoxicity. In these clinical studies dexrazoxane decreased the incidence of cardiac events and heart failure. Possible adverse effects of dexrazoxane when administered as a cardioprotective agent are a decreased antitumor effect of anthracyclines and the onset of secondary malignancies in children. As an antidote in anthracycline extravasation, clinical studies showed dexrazoxane to be highly efficacious in preventing the need for surgical resection. Dexrazoxane can be considered as the treatment of first choice for this indication. Dexrazoxane is well tolerated in general. The most commonly reported side effects are leukopenia, thrombocytopenia and local reactions at the infusion site.