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Aldo-keto reductase 1C3 (AKR1C3) is overexpressed in castration-resistant prostate cancer where it acts to drive proliferation and aggressiveness by producing androgens. The reductive action of the enzyme leads to chemoresistance development against various clinical antineoplastics across a range of cancers. Herein, we report the continued optimization of selective AKR1C3 inhibitors and the identification of 5r , a potent AKR1C3 inhibitor (IC 50 = 51 nM) with >1216-fold selectivity for AKR1C3 over closely related isoforms. Due to the cognizance of the poor pharmacokinetics associated with free carboxylic acids, a methyl ester prodrug strategy was pursued. The prodrug 4r was converted to free acid 5r in vitro in mouse plasma and in vivo. The in vivo pharmacokinetic evaluation revealed an increase in systemic exposure and increased the maximum 5r concentration compared to direct administration of the free acid. The prodrug 4r demonstrated a dose-dependent effect to reduce the tumor volume of 22Rv1 prostate cancer xenografts without observed toxicity.

Small-molecule tyrosine kinase inhibitors (TKIs) are novel anticancer agents with enhanced selectivity and superior safety profiles than conventional chemotherapeutics. A major shortcoming in TKI therapy is the development of acquired resistance. An important resistance mechanism is reduced intracellular drug accumulation due to an overexpression of efflux transporters such as P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) in cancer cells. TKIs have dual roles as substrates and inhibitors of Pgp and BCRP; thus, combination TKI therapy could potentially reverse efflux transporter-mediated TKI resistance. In the present study, the effect of 14 TKIs on Pgp-, Bcrp1-, and BCRP-mediated afatinib efflux was investigated in vitro. Nilotinib was a potent inhibitor of Pgp, Bcrp1, and BCRP, with EC 50 values of 2.22, 2.47, and 0.692 μM, respectively. Consequently, the pharmacokinetics of afatinib with and without the coadministration of nilotinib was determined in mice plasma and various tissues. Nilotinib increased afatinib AUC by 188% in plasma, and this altered tissue AUC by -38.8% to +221%. Nilotinib also decreased the clearance of afatinib by 65.3%, from 609 to 211 mL/h. Further studies are warranted to assess nilotinib's chemosensitizing effect in tumor xenograft models., (Copyright © 2019 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Background: The activity of MP1, a pyrrolomycin, was studied in MYCN amplified neuroblastoma (NB) alone and combined with temsirolimus (TEM)., Methods: Activity of MP1 was tested in MYCN amplified (BE-2c, IMR) and non amplified (SKN-AS) NB cells. The effect of MP1 on MYCN, MCL-1, cleaved PARP, LC3II/LC3I, bcl-2, BAX, and BRD-4 were determined by western blot and RNAseq. The effect of MP1 on metabolism, mitochondrial morphology, and cell cycle was determined. Toxicology and efficacy of MP1 plus TEM were evaluated., Results: The IC 50 of MP1 was 0.096 μM in BE-2c cells compared to 0.89 μM in IMR, and >50 μM in SKN-AS. The IC 50 of MP1 plus TEM in BE-2c cells was 0.023 μM. MP1 inhibited metabolism leading to quiescence and produced a decline in cell cycle S-phase. Electron microscopy showed cristae loss and rounding up of mitochondria. Gene and protein expression for MYCN and MCL-1 declined while LCII and cleaved PARP increased. Protein expression of BAX, bcl-2, and BRD-4 were not significantly changed after MP1 treatment. The in-vivo concentrations of MP1 in blood and tumor were sufficient to produce the biologic effects seen in-vitro. MP1 plus TEM produced a complete response in 3 out of 5 tumor bearing mice. In a second mouse study, the combination of MP1 and TEM slowed tumor growth compared to control., Conclusions: MP1 has a potent inhibitory effect on the viability of MYCN amplified NB. Inhibition of metabolism by MP1 induced quiescence and autophagy with a favorable toxicology and drug distribution profile. When combined with TEM anti-tumor activity was potentiated in-vitro and in-vivo.

Fluoroquinolone-class agents selectively target the bacterial type IIA topoisomerases DNA gyrase and topoisomerase IV, with a few exceptions that target eukaryotic type IIA topoisomerases. Fluoroquinolones bind and stabilize type IIA topoisomerase-DNA covalent complexes that contain a double-strand break. This unique mode of action is referred to as 'topoisomerase poisoning'. We discovered that two novel fluoroquinolones having aryl functionality at the N-1 position, UITT-3-217 (217) and UITT-3-227 (227), could inhibit the catalytic activity of human topoisomerase II without stabilizing topoisomerase-DNA complexes, i.e., without poisoning it. Surprisingly, these compounds are more effective in inhibiting the catalytic activities of human and bacterial topoisomerase I. The National Cancer Institute's 60 human tumor cell lines screen revealed significant anti-proliferative activities with 217 and 227 against the majority of 60 cancer cell lines. A proof of concept in vivo efficacy study using an HT-29 xenograft model of human colorectal cancer showed that 217 could inhibit the proliferation of human colorectal cancer cells to a degree comparable to fluorouracil in mice. Although 227 also exhibited anti-proliferative activity, it was not as effective as 217 in this xenograft model. These novel fluoroquinolones may serve as promising lead compounds for the development of new anticancer drugs.

Geranylgeranyl diphosphate synthase (GGDPS) is the enzyme in the isoprenoid biosynthesis pathway that catalyzes the synthesis of the 20-carbon isoprenoid GGPP, which serves as the isoprenoid donor for protein geranylgeranylation reactions. Rab proteins mediate vesicle trafficking within the cell and their activity is dependent on geranylgeranylation. Our prior work has demonstrated that agents that disrupt Rab geranylgeranylation disrupt monoclonal protein trafficking in myeloma cells, resulting in induction of the unfolded protein response pathway and apoptosis. VSW1198 is a potent GGDPS inhibitor with measurable cellular activity at concentrations as low as 30 nM. Due to its potent activity against myeloma cells in vitro, we were interested in evaluating the toxicology profile, pharmacokinetic (PK) profile, tissue distribution pattern and metabolic stability of VSW1198 in preparation for in vivo efficacy studies. Single dose testing via IV administration in CD-1 mice revealed a maximum tolerated dose of 0.5 mg/kg. Doses ≥1 mg/kg resulted in liver toxicity that peaked around 6-7 days post-injection. Disruption of protein geranylgeranylation following repeat dosing of VSW1198 was confirmed via immunoblot analysis of unmodified Rap1a in multiple organs. The PK studies revealed a half-life of 47.7 ± 7.4 h. VSW1198 was present in all tested tissues with the highest levels in the liver. In both human liver microsomes and mouse S9 studies VSW1198 showed complete stability, suggesting no phase I or phase II metabolism. In summary, these studies demonstrate systemic distribution, on-target disruption of protein geranylgeranylation, and metabolic stability of a potent GGDPS inhibitor VSW1198 and form the basis for future efficacy studies in mouse models of myeloma.

An isomeric mixture of homogeranyl/homoneryl triazole bisphosphonates (VSW1198) has previously been shown to be a potent inhibitor of geranylgeranyl diphosphate (GGDP) synthase (GGDPS) and of therapeutic interest for the treatment of multiple myeloma. We have developed and validated a selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitation of both the E- and Z- isomers of VSW1198 in cell culture media, mouse plasma and tissues. VSW1198 and internal standard are extracted from the bio-matrices by solid-phase extraction, followed by derivatization using trimethylsilyldiazomethane. The chromatographic separation of analytes was achieved on a Phenomenex Gemini NX column (150 mm * 2.0 mm, 5 μ) with gradient elution using 0.1% acetic acid and methanol/acetonitrile (1:1) as the mobile phase at a flow rate of 0.2 mL/min. Derivatized analytes were ionized with an electrospray ionization source in positive multiple reaction monitoring (MRM) mode and quantitated using MS/MS. The MS/MS response was linear over the concentration range from 0.38-1500 and 0.13-500 ng/mL for the E- and Z-isomers, respectively. The within- and between-day precision (relative standard deviation, % RSD) and accuracy were within the acceptable limits per FDA guidelines. The validated method was used for quantitative determination of the compounds in preclinical studies focused on the development of VSW1198 as a novel anti-cancer agent., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Uterine serous carcinoma, one of the most aggressive types of endometrial cancer, is characterized by poor outcomes and mutations in the tumour suppressor p53. Our objective was to engender synthetic lethality to paclitaxel (PTX), the frontline treatment for endometrial cancer, in tumours with mutant p53 and enhance the therapeutic efficacy using polymeric nanoparticles (NPs). First, we identified the optimal NP formulation through comprehensive analyses of release profiles and cellular-uptake and cell viability studies. Not only were PTX-loaded NPs superior to PTX in solution, but the combination of PTX-loaded NPs with the antiangiogenic molecular inhibitor BIBF 1120 (BIBF) promoted synthetic lethality specifically in cells with the loss-of-function (LOF) p53 mutation. In a xenograft model of endometrial cancer, this combinatorial therapy resulted in a marked inhibition of tumour progression and extended survival. Together, our data provide compelling evidence for future studies of BIBF- and PTX-loaded NPs as a therapeutic opportunity for LOF p53 cancers.

The overexpression of efflux transporters, especially P-glycoprotein (Pgp, MDR1, ABCB1) and breast cancer resistance protein (BCRP, ABCG2), represents an important mechanism of multidrug resistance (MDR). Tyrosine kinase inhibitors (TKIs), a novel group of target-specific anticancer drugs, have recently been found to interact with Pgp and BCRP and to serve as both substrates and inhibitors. Considering their dual role, we anticipate that combination TKI therapy may represent a promising strategy to reverse efflux transporter mediated TKI resistance. Presently, investigations on these interactions are very limited. To fill the literature gap, dasatinib was used as the model drug and the effects of various TKIs on Pgp- and BCRP- mediated dasatinib efflux were evaluated. Cell uptake studies were performed using LLC-PK1 and MDCK-II cells along with their subclones that were transfected with human Pgp and BCRP, respectively. Among the 14 TKIs screened, nine TKIs greatly inhibited Pgp-mediated dasatinib efflux at 50 μm. Further concentration dependent studies showed that imatinib, nilotinib and pazopanib were potent Pgp inhibitors with IC 50 values of 2.42, 6.11 and 8.06 μm, respectively. Additionally, 50 μm of five TKIs greatly increased dasatinib accumulation through BCRP inhibition. Concentration dependent studies revealed that imatinib, erlotinib, nilotinib, axitinib and pazopanib were potent BCRP inhibitors with IC 50 values of 0.94, 2.23, 2.50, 6.89 and 10.4 μm, respectively. Our findings point to potential combinations of TKIs that could enhance intracellular concentrations of the targeted TKI, overcome MDR and improve TKI efficacy. Further in vivo studies are warranted to confirm the efflux transporter-mediated TKI-TKI interaction. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Gefitinib (Iressa) is a selective and potent EGFR tyrosine kinase inhibitor. It received an accelerated FDA approval in 2003 for the treatment of patients with nonsmall cell lung cancer (NSCLC) and represents the first-line therapy for NSCLC with EGFR mutations. In the work presented herein, the disposition of gefitinib was investigated extensively in mouse in both plasma and 11 organs (liver, heart, lung, spleen, gut, brain, skin, fat, eye, kidney, and muscle) after a single IV dose of 20 mg/kg. Gefitinib demonstrated extensive distribution in most tissues, except for the brain, and tissue to plasma partition coefficients (K pt) ranged from 0.71 (brain) to 40.5 (liver). A comprehensive whole-body physiologically based pharmacokinetic (PBPK) model of gefitinib in mice was developed, which adequately captured gefitinib concentration-time profiles in plasma and various tissues. Predicted plasma and tissue AUC values agreed well with the values calculated using the noncompartmental analysis (<25% difference). The PBPK model was further extrapolated to humans after taking into account the interspecies differences in physiological parameters. The simulated concentrations in human plasma were in line with the observed concentrations in healthy volunteers and patients with solid malignant tumors after both IV infusion and oral administration. Considering the extensive tissue distribution of gefitinib, plasma concentration may not be an ideal surrogate marker for gefitinib exposure at the target site or organ of toxicity (such as the skin). Since our whole-body PBPK model can predict gefitinib concentrations not only in plasma but also in various organs, our model may have clinical applications in efficacy and safety assessment of gefitinib.

Purpose: We sought to characterize the pharmacokinetics (PK) and determine a tolerable dose of oral sorafenib in patients with hepatic or renal dysfunction., Patients and Methods: Patients were assigned to one of nine cohorts: cohort 1, bilirubin < or = upper limit of normal (ULN) and AST < or = ULN and creatinine clearance (CC) > or = 60 mL/min; cohort 2, bilirubin more than ULN but < or = 1.5x ULN and/or AST more than ULN; cohort 3, CC between 40 and 59 mL/min; cohort 4, bilirubin more than 1.5x ULN to < or = 3x ULN (any AST); cohort 5, CC between 20 and 39 mL/min; cohort 6, bilirubin more than 3x ULN to 10x ULN (any AST); cohort 7, CC less than 20 mL/min; cohort 8, albumin less than 2.5 mg/dL (any bilirubin/AST); and cohort 9, hemodialysis. Sorafenib was administered as a 400-mg dose on day 1 for PK, and continuous daily dosing started on day 8., Results: Of 150 registered patients, 138 patients were treated. With the exception of cohorts 6 and 7, at least 12 patients per cohort were assessable, and the dose level with prospectively defined dose-limiting toxicity in less than one third of patients by day 29 was considered tolerable. No significant associations between the sorafenib PK and cohort were found., Conclusion: We recommend the following empiric sorafenib starting doses by cohort: cohort 1, 400 mg twice a day; cohort 2, 400 mg twice a day; cohort 3, 400 mg twice a day; cohort 4, 200 mg twice a day; cohort 5, 200 mg twice a day; cohort 6, not even 200 mg every third day tolerable; cohort 7, not defined; cohort 8, 200 mg each day; and cohort 9, 200 mg each day.

Lovastatin, an inhibitor of the rate-limiting enzyme in the cholesterol biosynthetic pathway, hydroxymethylglutaryl coenzyme A reductase, has shown interesting antiproliferative activities in cell culture and in animal models of cancer. The goal of the current study is to determine whether lovastatin bioactivity levels, in a range equivalent to those used in in vitro and preclinical studies, can be safely achieved in human subjects. Here we present the findings from a dose-escalating trial of lovastatin in subjects with advanced malignancies. Lovastatin was administered every 6 h for 96 h in 4-week cycles in doses ranging from 10 mg/m2 to 415 mg/m2. Peak plasma lovastatin bioactivity levels of 0.06-12.3 microM were achieved in a dose-independent manner. Cholesterol levels decreased during treatment and normalized during the rest period. A dose-limiting toxicity was not reached and there were no clinically significant increases in creatine phosphokinase or serum hepatic aminotransferases levels. No antitumor responses were observed. These results demonstrate that high doses of lovastatin, given every 4 h for 96 h, are well-tolerated and in select cases, bioactivity levels in the range necessary for antiproliferative activity were achieved.

Objective: To determine the maximum tolerated dose (MTD) of cisplatin administered with piroxicam, the antitumor activity and toxicity of cisplatin combined with piroxicam in dogs with oral malignant melanoma (OMM) and oral squamous cell carcinoma (SCC), and the effects of piroxicam on the pharmacokinetics of cisplatin in dogs with tumors., Design: Prospective nonrandomized clinical trial., Animals: 25 dogs., Procedure: Dogs were treated with a combination of cisplatin (escalating dose with 6 hours of diuresis with saline [0.9% NaCI] solution) and piroxicam (0.3 mg/kg 10.14 mg/lb], PO, q 24 h). The initial cisplatin dose (50 mg/m2) was increased by 5 mg/m2 until the MTD was reached. Tumor stage and size were determined at 6-week intervals during treatment. The pharmacokinetics of cisplatin were determined in dogs receiving a combination of cisplatin and piroxicam during the clinical trial and dogs that were treated with cisplatin alone., Results: 11 dogs with OMM and 9 dogs with SCC were included in the clinical trial. The MTD of cisplatin when administered in combination with piroxicam was 50 mg/m2. Tumor remission occurred in 5 of 9 dogs with SCC and 2 of 11 dogs with OMM. The most common abnormality observed was renal toxicosis. Clearance of cisplatin in dogs that were treated with cisplatin alone was not significantly different from that in dogs treated with a combination of cisplatin and piroxicam., Conclusions and Clinical Relevance: Cisplatin administered in combination with piroxicam had antitumor activity against OMM and SCC. The level of toxicity was acceptable, although renal function must be monitored carefully.

Purpose: Phenylacetate (PAA), a deaminated metabolite of phenylalanine, suppresses tumor growth and induces differentiation in preclinical tumor models. We performed a pharmacokinetic study, as part of a phase I trial, of PAA in children with refractory cancer., Methods: PAA was administered as a 30-min i.v. infusion at a dose of 1.8 or 2.5 g/m2. Serial plasma samples were collected for up to 24 h after the end of the infusion in 27 children. The concentrations of PAA and its inactive metabolite, phenylacetylglutamine (PAG), were measured using a reverse-phase high-performance liquid chromatography assay with ultraviolet detection., Results: PAA and PAG concentrations were best described by a two-compartment model (one compartment for each compound) with capacity-limited conversion of PAA to PAG. The half-life of PAA was 55+/-18 min at the 1.8 g/m2 dose and 77+/-22 min at the 2.5 g/m2 dose. The half-life of PAG was 112+/-53 min at the 1.8 g/m2 dose and 135+/-75 min at the 2.5 g/m2 dose. The clearance of PAA was 66+/-33 ml/min per m2 at the 1.8 g/m2 dose and 60+/-24 ml/min per m2 at the 2.5 g/m2 dose. The Michaelis-Menten constants describing the conversion of PAA to PAG in the model (Vm and Km) were (means+/-SD) 18.4+/-13.8 mg/m2 per min and 152+/-155 microg/ml, respectively. The volumes of distribution for PAA and PAG (V(d-PAA) and V(d-PAG)) were 7.9+/-3.4 l/m2 and 34.4+/-16.1 l/m2, respectively. The first-order elimination rate constant for PAG (k(e-PAG)) was 0.0091+/-0.0039 min(-1)., Conclusions: The capacity-limited conversion of PAA to PAG has important implications for the dosing of PAA, and the pharmacokinetic model described here may be useful for individualizing the infusion rate of the drug in future clinical trials.

Background: Medulloblastoma (MB) patients with MYC oncogene amplification or overexpression exhibit extremely poor prognoses and therapy resistance. However, MYC itself has been one of the most challenging targets for cancer treatment. Here, we identify a novel marinopyrrole natural derivative, MP1, that shows desirable anti-MYC and anti-cancer activities in MB. Methods: In this study, using MYC-amplified (Group 3) and non-MYC amplified MB cell lines in vitro and in vivo, we evaluated anti-cancer efficacies and molecular mechanism(s) of MP1. Results: MP1 significantly suppressed MB cell growth and sphere counts and induced G2 cell cycle arrest and apoptosis in a MYC-dependent manner. Mechanistically, MP1 strongly downregulated the expression of MYC protein. Our results with RNA-seq revealed that MP1 significantly modulated global gene expression and inhibited MYC-associated transcriptional targets including translation/mTOR targets. In addition, MP1 inhibited MYC-target metabolism, leading to declined energy levels. The combination of MP1 with an FDA-approved mTOR inhibitor temsirolimus synergistically inhibited MB cell growth/survival by downregulating the expression of MYC and mTOR signaling components. Our results further showed that as single agents, both MP1 and temsirolimus, were able to significantly inhibit tumor growth and MYC expression in subcutaneously or orthotopically MYC-amplified MB bearing mice. In combination, there were further anti-MB effects on the tumor growth and MYC expression in mice. Conclusion: These preclinical findings highlight the promise of marinopyrrole MP1 as a novel MYC inhibition approach for MYC-amplified MB. [ABSTRACT FROM AUTHOR]

Background: The purpose of the current study was to evaluate the activity and toxicity of dexamethasone, high-dose cytarabine, and carboplatin (DAC) combination therapy in children with newly diagnosed large-cell non-Hodgkin lymphoma (NHL) and to estimate the event-free and overall survival rates achieved when DAC is incorporated into a conventional regimen.Methods: From 1991 to 1997, 20 boys and 5 girls aged 4.2 to 17.7 years who had stage III (according to the St. Jude staging system) (n = 21) or stage IV (n = 4) large-cell NHL were treated in this study. DAC therapy was administered at the beginning of the induction phase in 2 sequential cycles and incorporated throughout a continuation phase (modified from the ACOP+ regimen, which features doxorubicin, cyclophosphamide, vincristine, and prednisone) with doxorubicin, cyclophosphamide, vincristine, and dexamethasone. The total duration of treatment was approximately 10 months.Results: DAC therapy yielded a response in 22 of 25 patients (88%; 95% confidence interval [95% CI], 68%-97%): complete remission in 13 cases (52%), and partial response in 9 (36%). After additional treatment with doxorubicin, cyclophosphamide, vincristine, and dexamethasone, complete remission was attained in 18 patients (72%) and partial remission in 3 (12%). The event-free survival rate (+/- the standard error [SE]) was 64% +/- 9% and the overall survival rate was 80% +/- 8% at 5 years.Conclusions: The results of the current study indicate that the DAC regimen is well tolerated and effective for pediatric patients with large-cell NHL. [ABSTRACT FROM AUTHOR]

Abstract: This study characterized interactions between efflux transporters (P-glycoprotein (MDR1) and multidrug resistance associated proteins (MRPs1–3)) and vincristine (VCR), using cell lines with differential transporter expression, and studied effects of P-glycoprotein inhibition on VCR transport and toxicity. Caco2 (express MDR1, MRPs 1–3), LS174T (express MDR1, MRPs 1, 3), and A549 (express MRPs 1–3) cells were used. To study VCR transport (effective permeability, P eff), VCR (1–500nM) was added to the donor chambers of permeable supports containing Caco2 monolayers, and receiving chamber concentrations were measured. Cytotoxicity experiments were conducted with escalating concentrations of VCR in all cell lines. To determine the contribution of MDR1, experiments were also conducted with LY335979, a specific MDR1 inhibitor. VCR P eff was 2×10−6 cm/s in Caco2 cells. LY335979 increased P eff in a dose dependent manner (up to 7-fold with 1μM LY335979) in Caco2 cells. Caco2 and LS174T cell viability decreased significantly when co-incubated with both VCR and LY335979 (1μM) (P <0.05), however this was not observed in A549 cells. In summary, MDR1 plays an important role in VCR efflux; MDR1 inhibition increased VCR P eff in Caco2 cells, and increased VCR cytotoxicity in Caco2 and LS174T cells (both express MDR1), but not A549 cells (minimal MDR1 expression). Inhibition of MDR1 may be a viable strategy to overcome VCR resistance in tumors expressing MDR1, however the presence of other efflux transporters should also be considered, as this will influence the success of such strategies. [Copyright &y& Elsevier]

Abstract: An LC-MS method using APCI has been developed and validated for the determination of the anticancer drug vincristine in human plasma, using vinblastine as internal standard. Following solid-phase extraction (SPE) of the sample, the lower limit of quantitation (LLOQ) was 0.18ng/ml, the lower limit of detection was 0.09ng/ml, and the linear calibration range was 0.18–180ng/ml. This method has been used to measure plasma concentrations of vincristine from 0.08 to 24h post bolus in 29 infants as part of a pharmacokinetic study. Concentrations of vincristine at 24h were 0.2–1.36ng/ml. [Copyright &y& Elsevier]