[show abstract][hide abstract] ABSTRACT: Benzaldehyde dimethane sulfonate (DMS612, NSC281612, BEN) is an alkylator with activity against renal cell carcinoma, currently in phase I trials. In blood, BEN is rapidly metabolized into its highly reactive carboxylic acid (BA), presumably the predominant alkylating species. We hypothesized that BEN is metabolized to BA by aldehyde dehydrogenase (ALDH) and aimed to increase BEN exposure in blood and tissues by inhibiting ALDH with disulfiram, thereby shifting BA production from blood to tissues.
Female CD2F1 mice were dosed with 20 mg/kg BEN iv alone or 24 h after 300 mg/kg disulfiram ip. BEN, BA, and metabolites were quantitated in plasma and urine, and toxicities were assessed.
BEN had a plasma t½ <5 min and produced at least 12 products. The metabolite half-lives were <136 min. Disulfiram increased BEN plasma exposure 368-fold (AUC0-inf from 0.11 to 40.5 mg/L min), while plasma levels of BA remained similar. Urinary BEN excretion increased (1.0-1.5 % of dose), while BA excretion was unchanged. Hematocrit, white blood cell counts, and percentage lymphocytes decreased after BEN administration. Coadministration of disulfiram appeared to enhance these effects. Profound liver pathology was observed in mice treated with disulfiram and BEN.
BEN plasma concentrations increased after administration of disulfiram, suggesting that ALDH mediates the rapid metabolism of BEN in vivo, which may explain the increased toxicity seen with BEN after administration of disulfiram. Our results suggest that the coadministration of BEN with drugs that inhibit ALDH to patients that are ALDH deficient may cause liver damage.
Cancer Chemotherapy and Pharmacology 09/2013; · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Photodynamic Therapy (PDT) holds great promise for the treatment of head and neck (H&N) carcinomas where repeated loco-regional therapy often becomes necessary due to the highly aggressive and recurrent nature of the cancers. While interstitial light delivery technologies are being refined for PDT of H&N and other cancers, a parallel clinically relevant research area is the formulation of photosensitizers in nanovehicles that allow systemic administration yet preferential enhanced uptake in the tumor. This approach can render dual-selectivity of PDT, by harnessing both the drug and the light delivery within the tumor. To this end, we report on a cell-targeted nanomedicine approach for the photosensitizer silicon phthalocyanine-4 (Pc 4), by packaging it within polymeric micelles that are surface-decorated with GE11-peptides to promote enhanced cell-selective binding and receptor-mediated internalization in EGFR-overexpressing H&N cancer cells. Using fluorescence spectroscopy and confocal microscopy, we demonstrate in vitro that the EGFR-targeted Pc 4-nanoformulation undergoes faster and higher uptake in EGFR-overexpressing H&N SCC-15 cells. We further demonstrate that this enhanced Pc 4 uptake results in significant cell-killing and drastically reduced post-PDT clonogenicity. Building on this in vitro data, we demonstrate that the EGFR-targeted Pc 4-nanoformulation results in significant intra-tumoral drug uptake and subsequent enhanced PDT response, in vivo, in SCC-15 xenografts in mice. Altogether our results show significant promise towards a cell-targeted photodynamic nanomedicine for effective treatment of H&N carcinomas.
[show abstract][hide abstract] ABSTRACT: PURPOSE: Protein kinase D (PKD) mediates diverse biological responses including cell growth and survival. Therefore, PKD inhibitors may have therapeutic potential. We evaluated the in vitro cytotoxicity of two PKD inhibitors, kb-NB142-70 and its methoxy analogue, kb-NB165-09, and examined their in vivo efficacy and pharmacokinetics. METHODS: The in vitro cytotoxicities of kb-NB142-70 and kb-NB165-09 were evaluated by MTT assay against PC-3, androgen-independent prostate cancer cells, and CFPAC-1 and PANC-1, pancreatic cancer cells. Efficacy studies were conducted in mice bearing either PC-3 or CPFAC-1 xenografts. Tumor-bearing mice were euthanized between 5 and 1,440 min after iv dosing, and plasma and tissue concentrations were measured by HPLC-UV. Metabolites were characterized by LC-MS/MS. RESULTS: kb-NB142-70 and kb-NB165-09 inhibited cellular growth in the low-mid μM range. The compounds were inactive when administered to tumor-bearing mice. In mice treated with kb-NB142-70, the plasma C (max) was 36.9 nmol/mL, and the PC-3 tumor C (max) was 11.8 nmol/g. In mice dosed with kb-NB165-09, the plasma C (max) was 61.9 nmol/mL, while the PANC-1 tumor C (max) was 8.0 nmol/g. The plasma half-lives of kb-NB142-70 and kb-NB165-09 were 6 and 14 min, respectively. Both compounds underwent oxidation and glucuronidation. CONCLUSIONS: kb-NB142-70 and kb-NB165-09 were rapidly metabolized, and concentrations in tumor were lower than those required for in vitro cytotoxicity. Replacement of the phenolic hydroxyl group with a methoxy group increased the plasma half-life of kb-NB165-09 2.3-fold over that of kb-NB142-70. Rapid metabolism in mice suggests that next-generation compounds will require further structural modifications to increase potency and/or metabolic stability.
Cancer Chemotherapy and Pharmacology 10/2012; · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Benzaldehyde dimethane sulfonate (BEN, DMS612, NSC281612) is an alkylating agent with activity against renal cell carcinoma and is being evaluated clinically. To support clinical trials, we developed an LC-MS/MS assay to detect and quantitate BEN and its metabolites/decomposition products. We tested the stability and products of BEN and benzoic acid dimethane sulfonate (BA) in plasma, blood and five renal carcinoma cell lines in vitro. Further, we determined the IC(50) of BEN, BA and four of their products in these cell lines. Low temperature and pH stabilized the analytes, and utilizing this resulted in an accurate, precise and reproducible assay. The half-lives of BEN and BA added to plasma in vitro were 220 and 5 min, while the half-life of BEN in whole blood was 18 min. The generation and degradation of up to 12 analytes were monitored, and structures confirmed with available authentic standards. The IC(50) for BEN was 5- to 500-fold lower than that of any of its products, while the cellular metabolic activity toward BEN correlated with ALDH activity and IC(50) values. We detected six of the in vitro products and their respective glucuronides in murine plasma after dosing BEN. The information gained from these experiments will be instrumental in the evaluation of the pharmacology of BEN in ongoing human trials.
Cancer Chemotherapy and Pharmacology 10/2012; · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Protein kinase D (PKD) acts as a major mediator of several signaling pathways related to cancer development. Aberrant PKD expression and activity have been shown in multiple cancers, and novel PKD inhibitors show promising anticancer activities. Despite these advances, the mechanisms through which PKD contributes to the pathogenesis of cancer remain unknown. Here, we establish a novel role for PKD3, the least studied member of the PKD family, in the regulation of prostate cancer cell growth and motility through modulation of secreted tumor-promoting factors. Using both a stable inducible knockdown cell model and a transient knockdown system using multiple siRNAs, we show that silencing of endogenous PKD3 significantly reduces prostate cancer cell proliferation, migration, and invasion. In addition, conditioned medium from PKD3-knockdown cells exhibits less migratory potential compared with that from control cells. Further analysis indicated that depletion of PKD3 blocks secretion of multiple key tumor-promoting factors including matrix metalloproteinase (MMP)-9, interleukin (IL)-6, IL-8, and GROα but does not alter mRNA transcript levels for these factors, implying impairment of the secretory pathway. More significantly, inducible depletion of PKD3 in a subcutaneous xenograft model suppresses tumor growth and decreases levels of intratumoral GROα in mice. These data validate PKD3 as a promising therapeutic target in prostate cancer and shed light on the role of secreted tumor-promoting factors in prostate cancer progression.
Molecular Cancer Therapeutics 04/2012; 11(7):1389-99. · 5.60 Impact Factor
[show abstract][hide abstract] ABSTRACT: Inositol hexaphosphate (IP(6)) is effective in preclinical cancer prevention and chemotherapy. In addition to cancer, IP(6) has many other beneficial effects for human health, such as reduction in risk of developing cardiovascular disease and diabetes and inhibition of kidney stone formation. Studies presented here describe the pharmacokinetics, tissue distribution, and metabolism of IP(6) following intravenous (IV) or per os (PO) administration to mice. SCID mice bearing MDA-MB-231 xenografts were treated with 20 mg/kg IP(6) (3 μCi per mouse [(14)C]-uniformly ring-labeled IP(6)) and euthanized at various times after IP(6) treatment. Plasma and tissues were analyzed for [(14)C]-IP(6) and metabolites by high-performance liquid chromatography with radioactivity detection. Following IV administration of IP(6), plasma IP(6) concentrations peaked at 5 minutes and were detectable until 45 minutes. Liver IP(6) concentrations were more than 10-fold higher than plasma concentrations, whereas other normal tissue concentrations were similar to plasma. Only inositol was detected in xenografts. After PO administration, IP(6) was detected in liver; but only inositol was detectable in other tissues. After both IV and PO administration, exogenous IP(6) was rapidly dephosphorylated to inositol; however, alterations in endogenous IPs were not examined.
Metabolism: clinical and experimental 04/2011; 60(10):1465-74. · 3.10 Impact Factor
[show abstract][hide abstract] ABSTRACT: Liposomes, such as pegylated-liposomal CKD-602 (S-CKD602), undergo catabolism by macrophages and dendritic cells (DCs) of the reticuloendothelial system (RES). The relationship between plasma and tumor disposition of S-CKD602 and RES was evaluated in mice bearing A375 melanoma or SKOV-3 ovarian xenografts. Area under the concentration-time curves (AUCs) of liposomal encapsulated, released, and sum total (encapsulated + released) CKD-602 in plasma, tumor, and tumor extracellular fluid (ECF) were estimated. A375 and SKOV-3 tumors were stained with cd11b and cd11c antibodies as measures of macrophages and DC. The plasma disposition of S-CKD602 was similar in both xenograft models. The ratio of tumor sum total AUC to plasma sum total AUC was 1.7-fold higher in mice bearing human SKOV-3 xenografts, compared with A375. The ratio of tumor ECF AUC to tumor sum total AUC was 2-fold higher in mice bearing human SKOV-3 xenografts, compared with A375. The staining of cd11c was 4.5-fold higher in SKOV-3, compared with A375 (P < 0.0001). The increased tumor delivery and release of CKD-602 from S-CKD602 in the ovarian xenografts, compared with the melanoma xenografts, was consistent with increased cd11c staining, suggesting that variability in the RES may affect the tumor disposition of liposomal agents.
Journal of Liposome Research 03/2011; 21(1):70-80. · 1.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: The c-Myc oncoprotein is overexpressed in many tumors and is essential for maintaining the proliferation of transformed cells. To function as a transcription factor, c-Myc must dimerize with Max via the basic helix-loop-helix leucine zipper protein (bHLH-ZIP) domains in each protein. The small molecule 7-nitro-N-(2-phenylphenyl)-2,1,3-benzoxadiazol-4-amine (10074-G5) binds to and distorts the bHLH-ZIP domain of c-Myc, thereby inhibiting c-Myc/Max heterodimer formation and inhibiting its transcriptional activity. We report in vitro cytotoxicity and in vivo efficacy, pharmacodynamics, pharmacokinetics, and metabolism of 10074-G5 in human xenograft-bearing mice. In vitro, 10074-G5 inhibited the growth of Daudi Burkitt's lymphoma cells and disrupted c-Myc/Max dimerization. 10074-G5 had no effect on the growth of Daudi xenografts in C.B-17 SCID mice that were treated with 20 mg/kg 10074-G5 intravenously for 5 consecutive days. Inhibition of c-Myc/Max dimerization in Daudi xenografts was not seen 2 or 24 h after treatment. Concentrations of 10074-G5 in various matrices were determined by high-performance liquid chromatography-UV, and metabolites of 10074-G5 were identified by liquid chromatography/tandem mass spectrometry. The plasma half-life of 10074-G5 in mice treated with 20 mg/kg i.v. was 37 min, and peak plasma concentration was 58 μM, which was 10-fold higher than peak tumor concentration. The lack of antitumor activity probably was caused by the rapid metabolism of 10074-G5 to inactive metabolites, resulting in tumor concentrations of 10074-G5 insufficient to inhibit c-Myc/Max dimerization. Our identification of 10074-G5 metabolites in mice will help design new, more metabolically stable small-molecule inhibitors of c-Myc.
Journal of Pharmacology and Experimental Therapeutics 12/2010; 335(3):715-27. · 3.89 Impact Factor
[show abstract][hide abstract] ABSTRACT: Cytidine drugs, such as gemcitabine, undergo rapid catabolism and inactivation by cytidine deaminase (CD). 3,4,5,6-tetrahydrouridine (THU), a potent CD inhibitor, has been applied preclinically and clinically as a modulator of cytidine analogue metabolism. However, THU is only 20% orally bioavailable, which limits its preclinical evaluation and clinical use. Therefore, we characterized THU pharmacokinetics after the administration to mice of the more lipophilic pro-drug triacetyl-THU (taTHU).
Mice were dosed with 150 mg/kg taTHU i.v. or p.o. Plasma and urine THU concentrations were quantitated with a validated LC-MS/MS assay. Plasma and urine pharmacokinetic parameters were calculated non-compartmentally and compartmentally.
taTHU did not inhibit CD. THU, after 150 mg/kg taTHU i.v., had a 235-min terminal half-life and produced plasma THU concentrations >1 μg/mL, the concentration shown to inhibit CD, for 10 h. Renal excretion accounted for 40-55% of the i.v. taTHU dose, 6-12% of the p.o. taTHU dose. A two-compartment model of taTHU generating THU fitted the i.v. taTHU data best. taTHU, at 150 mg/kg p.o., produced a concentration versus time profile with a plateau of approximately 10 μg/mL from 0.5-2 h, followed by a decline with a 122-min half-life. Approximately 68% of i.v. taTHU is converted to THU. Approximately 30% of p.o. taTHU reaches the systemic circulation as THU.
The availability of THU after p.o. taTHU is 30%, when compared to the 20% achieved with p.o. THU. These data will support the clinical studies of taTHU.
Cancer Chemotherapy and Pharmacology 05/2010; 67(2):421-30. · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Objective: In in vitro photodynamic therapy, the LD50 of Pc 181 has been reported to be 7 to 8 times less than that of silicon phthalocyanine 4 (Pc 4). The Optical Pharmacokinetic System (OPS) can measure photosensitizer concentrations in accessible tissues non-invasively. We used OPS to evaluate the tumor pharmacokinetics of Pc 181 and Pc 4 and the tissue drug distribution in SCID mice bearing either human breast cancer MDA-MB-231 or human head and neck squamous cell carcinoma SCC-15 xenografts. Methods: Following iv administration of 2.5 mg/kg Pc 181 or 2 mg/kg Pc 4 to SCID mice, OPS measurements were taken on tumor and normal tissues between 5 and 4320 min in vivo or in situ. Results: Large variations in tumor Pc 181 concentrations were observed among mice. In MDA-MB-231 tumors, the Pc 181 concentration peaked at 240 min, and was retained in the tumor. Tumor Pc 181 concentrations were much less than the tumor Pc 4 concentrations at an equimolar dose. Pc 181 concentrations were the highest in liver, followed by spleen, and kidney. In mice bearing SCC-15 xenografts, skin and underlying tissue Pc 181 concentrations were higher than tumor concentrations at all time points examined. Conclusions: This first Pc 181 pharmacokinetics study described a tissue Pc 181 distribution similar to that of Pc 4. However, tumor Pc 181 concentrations were lower than those of Pc 4 at equimolar doses.
[show abstract][hide abstract] ABSTRACT: Topoisomerase I (Topo I) is a recognized target for ovarian, lung, and colorectal cancer therapy. The FDA-approved camptothecin (CPT) Topo I inhibitors, topotecan and irinotecan are labile and their effects are rapidly reversible. The indenoisoquinoline topoisomerase I inhibitors, NSC 743400 and NSC 725776, have been developed as a new generation of Topo I inhibitors and are being advanced to clinical evaluation. To support the clinical development of NSC 743400 and NSC 725776, we developed and validated, according to FDA guidelines, LC-MS/MS assays for the sensitive, accurate and precise quantitation of NSC 743400 and NSC 725776 in 0.2 mL human plasma. After ethyl acetate extraction, separation was achieved with a Synergi Polar RP column and a gradient of 0.1% formic acid in acetonitrile:water. NSC 743400 and NSC 725776 eluted at approximately 3 min, and the total run time was 14 min. Detection consisted of electrospray, positive-mode ionization mass spectrometry. Between 3 and 1000 ng/mL, accuracy was 96.9-108.2% for NSC 743400 and 95.1-106.7% for NSC 725776, and precision was <11.4% for NSC 743400 and <5.9% for NSC 725776. Extraction recovery was >80% for both analytes, and ion suppression ranged from -46.7 to 5.7%. The use of isotopically labeled internal standards and a wash phase at the end of the run were necessary to achieve adequate assay performance. Protein binding in human plasma as assessed by equilibrium dialysis showed both indenoisoquinolines to be more than 98% protein bound.
Journal of pharmaceutical and biomedical analysis 02/2010; 52(5):714-20. · 2.45 Impact Factor
[show abstract][hide abstract] ABSTRACT: The ability to noninvasively measure photosensitizer concentration at target tissues will allow optimization of photodynamic therapy (PDT) and could improve outcome. In this study, we evaluated whether preirradiation tumor phthalocyanine 4 (Pc 4) concentrations, measured noninvasively by the optical pharmacokinetic system (OPS), correlated with tumor response to PDT. Mice bearing human breast cancer xenografts were treated with 2 mg kg(-1) Pc 4 iv only, laser irradiation (150 J cm(-2)) only, Pc 4 followed by fractionated irradiation or Pc 4 followed by continuous irradiation. Laser irradiation treatment was initiated when the tumor to skin ratio of Pc 4 concentration reached a maximum of 2.1 at 48 h after administration. Pc 4 concentrations in tumor, as well as in Intralipid in vitro, decreased monoexponentially with laser fluence. Pc 4-PDT resulted in significant tumor regression, and tumor response was similar in the groups receiving either fractionated or continuous irradiation treatment after Pc 4. Tumor growth delay following Pc 4-PDT correlated with OPS-measured tumor Pc 4 concentrations at 24 h prior to PDT (R2=0.86). In excised tumors, OPS-measured Pc 4 concentrations were similar to the HPLC-measured concentrations. Thus, OPS measurements of photosensitizer concentrations can be used to assist in the scheduling of Pc 4-PDT.
Photochemistry and Photobiology 04/2009; 85(4):1011-9. · 2.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Clinical use of radio- or photo-sensitizing agents in anti-cancer treatments may be limited by patient specific variability in the pharmacokinetics (PK) of the sensitizing compound. Previously, our group reported motexafin gadolinium (MGd) concentrations in mouse tissues measured noninvasively by the optical pharmacokinetic system (OPS) in vivo, nondestructively by OPS in situ, and destructively by HPLC ex vivo. This study utilized those reported data to develop compartmental PK models of MGd disposition in plasma, tumor, and skin. The model predicted both the rapid initial distribution and slow elimination phases of MGd in plasma, the fast transport of MGd out of the skin (with no MGd detectable after 120 min), and MGd retention at long times in the tumor (with detectable MGd at 24 h). The same compartmental structure was used to model MGd concentrations vs. time as measured by OPS in situ and HPLC ex vivo. In vivo tumor MGd concentrations measured using OPS were estimated by a linear combination of the model predicted PK profiles in plasma and tumor tissue, which suggests that tissue-specific PK knowledge may be needed in order to interpret volume-averaged optical measurements in vivo. The PK modeling techniques presented here are extensible to other optically active compounds and, potentially, to the development of patient-specific treatment schedules.
Photodiagnosis and photodynamic therapy 01/2009; 5(4):276-84.
[show abstract][hide abstract] ABSTRACT: Structure-activity studies centered on the naturally occurring antitumor agent dictyostatin have recently identified several highly active epimers and analogues. From these compounds, 6- epi-dictyostatin was selected for scaleup preparation and evaluation in animals. Here we describe a new total synthesis that produced more than 30 mg of 6- epi-dictyostatin. The compound was found to have potent antitumor activity in SCID mice bearing MDA-MB231 human breast cancer xenografts.
Journal of Medicinal Chemistry 11/2008; 51(21):6650-3. · 5.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: We evaluated the antitumor activity of two different schedules of docetaxel and 9-nitrocamptothecin (9NC) in mice bearing human SKOV-3 ovarian carcinoma xenografts and evaluated the plasma, tissue, and tumor disposition of each agent alone and in combination.
The following treatment groups were evaluated: (1) docetaxel 10 mg/kg IV on days 0 and 7; (2) 9NC 0.67 mg/kg PO qdx5dx2wk; (3) 9NC 0.67 mg/kg PO qdx5dx2wk in combination with docetaxel 10 mg/kg IV on days 0 and 7; and (4) 9NC 0.67 mg/kg PO qdx5dx2wk in combination with docetaxel 10 mg/kg IV on days 4 and 11; (5) vehicle controls for each agent; and (6) no treatment controls.
All treatment regimens produced significant antitumor activity as compared with control groups (P < 0.05). Docetaxel administered on days 0 and 7 or on days 4 and 11 in combination with 9NC resulted in similar antitumor activity (P > 0.05). High docetaxel concentrations in tumor were maintained at late time points as compared with plasma and tissues with the retention of docetaxel at 24 h being 132-fold and 15-fold higher in tumor than in plasma and liver, respectively. After administration of 9NC alone, the ratio of the 9-aminocamptothecin (9AC) area under the concentration versus time curve (AUC) to 9NC AUC in plasma and tumor was 0.15 and 1.34, respectively.
The combination of docetaxel and 9NC was effective against SKOV-3 xenografts. The lack of a difference in sequence-dependent antitumor activity may reflect the sensitivity of the SKOV-3 xenograft to 9NC. The factors associated with tumor-specific retention of docetaxel and the ratio of 9NC to 9AC in tumors is unknown.
Cancer Chemotherapy and Pharmacology 08/2008; 62(3):417-26. · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Cytidine analogues such as cytosine arabinoside, gemcitabine, decitabine, 5-azacytidine, 5-fluoro-2'-deoxycytidine and 5-chloro-2'-deoxycytidine undergo rapid catabolism by cytidine deaminase (CD). 3,4,5,6-tetrahydrouridine (THU) is a potent CD inhibitor that has been applied preclinically and clinically as a modulator of cytidine analogue metabolism. However, THU pharmacokinetics has not been fully characterized, which has impaired the optimal preclinical evaluation and clinical use of THU. Therefore, we characterized the THU pharmacokinetics and bioavailability in mice. Mice were dosed with THU iv (100 mg/kg) or po (30, 100, or 300 mg/kg). Plasma and urine THU concentrations were quantitated with a validated LC-MS/MS assay. Plasma pharmacokinetic parameters were calculated compartmentally and non-compartmentally. THU, at 100 mg/kg iv had a 73 min terminal half-life and produced plasma THU concentrations >1 microg/ml, the concentration shown to effectively block deamination, for 4 h. Clearance was 9.1 ml/min/kg, and the distribution volume was 0.95 l/kg. Renal excretion accounted for 36-55% of the THU dose. A three-compartment model fit the iv THU data best. THU, at 100 mg/kg po, produced a concentration versus time profile with a plateau of approximately 10 mug/ml from 0.5-3 h, followed by a decline with an 85 min half-life. The oral bioavailability of THU was approximately 20%. The 20% oral bioavailability of THU is sufficient to produce and sustain, for several hours, plasma concentrations that inhibit CD. This suggests the feasibility of using THU to decrease elimination and first-pass metabolism of cytidine analogues by CD. THU pharmacokinetics are now being evaluated in humans.
Cancer Chemotherapy and Pharmacology 08/2008; 62(3):457-64. · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: c-Myc is commonly activated in many human tumors and is functionally important in cellular proliferation, differentiation, apoptosis and cell cycle progression. The activity of c-Myc requires noncovalent interaction with its client protein Max. In vitro studies indicate the thioxothiazolidinone, 10058-F4, inhibits c-Myc/Max dimerization. In this study, we report the efficacy, pharmacokinetics and metabolism of this novel protein-protein disruptor in mice.
SCID mice bearing DU145 or PC-3 human prostate cancer xenografts were treated with either 20 or 30 mg/kg 10058-F4 on a qdx5 schedule for 2 weeks for efficacy studies. For pharmacokinetics and metabolism studies, mice bearing PC-3 or DU145 xenografts were treated with 20 mg/kg of 10058-F4 i.v. Plasma and tissues were collected 5-1440 min after dosing. The concentration of 10058-F4 in plasma and tissues was determined by HPLC, and metabolites were characterized by LC-MS/MS.
Following a single iv dose, peak plasma 10058-F4 concentrations of approximately 300 muM were seen at 5 min and declined to below the detection limit at 360 min. Plasma concentration versus time data were best approximated by a two-compartment, open, linear model. The highest tissue concentrations of 10058-F4 were found in fat, lung, liver, and kidney. Peak tumor concentrations of 10058-F4 were at least tenfold lower than peak plasma concentrations. Eight metabolites of 10058-F4 were identified in plasma, liver, and kidney. The terminal half-life of 10058-F4 was approximately 1 h, and the volume of distribution was >200 ml/kg. No significant inhibition of tumor growth was seen after i.v. treatment of mice with either 20 or 30 mg/kg 10058-F4.
The lack of significant antitumor activity of 10058-F4 in tumor-bearing mice may have resulted from its rapid metabolism and low concentration in tumors.
Cancer Chemotherapy and Pharmacology 06/2008; 63(4):615-25. · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: In vivo, 2',2'-difluoro-2'-deoxycytidine (dFdC) is rapidly inactivated by gut and liver cytidine deaminase (CD) to 2',2'-difluoro-2'-deoxyuridine (dFdU). Consequently, dFdC has poor oral bioavailability and is administered i.v., with associated costs and limitations in administration schedules. 3,4,5,6-Tetrahydrouridine (THU) is a potent CD inhibitor with a 20% oral bioavailability. We investigated the ability of THU to decrease elimination and first-pass effect by CD, thereby enabling oral dosing of dFdC.
A liquid chromatography-tandem mass spectrometry assay was developed for plasma dFdC and dFdU. Mice were dosed with 100 mg/kg dFdC i.v. or orally with or without 100 mg/kg THU i.v. or orally. At specified times between 5 and 1,440 min, mice (n = 3) were euthanized. dFdC, dFdU, and THU concentrations were quantitated in plasma and urine.
THU i.v. and orally produced concentrations >4 microg/mL for 3 and 2 h, respectively, whereas concentrations of >1 microg/mL have been associated with near-complete inhibition of CD in vitro. THU i.v. decreased plasma dFdU concentrations but had no effect on dFdC plasma area under the plasma concentration versus time curve after i.v. dFdC dosing. Both THU i.v. and orally substantially increased oral bioavailability of dFdC. Absorption of dFdC orally was 59%, but only 10% passed liver and gut CD and eventually reached the systemic circulation. Coadministration of THU orally increased dFdC oral bioavailability from 10% to 40%.
Coadministration of THU enables oral dosing of dFdC and warrants clinical testing. Oral dFdC treatment would be easier and cheaper, potentially prolong dFdC exposure, and enable exploration of administration schedules considered impractical by the i.v. route.
Clinical Cancer Research 06/2008; 14(11):3529-35. · 7.84 Impact Factor
[show abstract][hide abstract] ABSTRACT: A nonlinear model predictive control (NMPC) algorithm was developed to dose the chemotherapeutic agent tamoxifen based on a novel saturating-rate, cell-cycle model (SCM). Using daily tumor measurements, the algorithm decreased tumor volume along a specified reference trajectory in simulated animals over 4 months. In mismatch case studies, controllers based on the Gompertz model (GM) yielded equivalent total drug delivered and elapsed time to t(99%) reference step convergence to those obtained using the SCM, though this performance was dependent on the cell-cycle phase of drug effect. Overall, the NMPC algorithm is suitable for dosing chemotherapeutics with regular administration schedules and may be adapted for regularly administered chemotherapeutics other than tamoxifen.
Computers in Biology and Medicine 04/2008; 38(3):339-47. · 1.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: 2,2-Dimethylbutyrate (DMB) is a potential treatment for thalassemia and hemoglobinopathies. To facilitate pharmacokinetic evaluation of DMB, we developed an LC-MS assay and quantitated DMB in plasma of rats after an oral dose of 500mg/kg. After acetonitrile protein precipitation, DMB and dimethylvaleric acid (DMV) internal standard were derivatized to benzylamides, chromatographed on a Hydro-RP column with acetonitrile, water, and 0.1% formic acid, and detected by electrospray positive-mode ionization mass spectrometry. The assay was accurate (97-107%) and precise (3.4-6.2%) between 100 and 10,000ng/mL. Recovery from plasma was >62%. Plasma freeze-thaw and room temperature stability were acceptable.
Journal of Chromatography B 03/2008; 862(1-2):168-74. · 2.49 Impact Factor