Foliate-Targeting Quantum Dots-ß-Cyclodextrin Nanocarrier for Efficient Delivery of Unsymmetrical Bisacridines to Lung and Prostate Cancer Cells.

Targeted drug delivery by nanocarriers molecules can increase the efficiency of cancer treatment. One of the targeting ligands is folic acid (FA), which has a high affinity for the folic acid receptors, which are overexpressed in many cancers. Herein, we describe the preparation of the nanoconjugates containing quantum dots (QDs) and ß-cyclodextrin (ß-CD) with foliate-targeting properties for the delivery of anticancer compound C-2028. C-2028 was bound to the nanoconjugate via an inclusion complex with ß-CD. The effect of using FA in QDs-ß-CD(C-2028)-FA nanoconjugates on cytotoxicity, cellular uptake, and the mechanism of internalization in cancer (H460, Du-145, and LNCaP) and normal (MRC-5 and PNT1A) cells was investigated. The QDs-ß-CD(C-2028)-FA were characterized using DLS (dynamic light scattering), ZP (zeta potential), quartz crystal microbalance with dissipation (QCM-D), and UV-vis spectroscopy. The conjugation of C-2028 with non-toxic QDs or QDs-ß-CD-FA did not change the cytotoxicity of this compound. Confocal microscopy studies proved that the use of FA in nanoconjugates significantly increased the amount of delivered compound, especially to cancer cells. QDgreen-ß-CD(C-2028)-FA enters the cells through multiple endocytosis pathways in different levels, depending on the cell line. To conclude, the use of FA is a good self-navigating molecule in the QDs platform for drug delivery to cancer cells.

Rifampin and ritonavir increase oral availability and elacridar enhances overall exposure and brain accumulation of the NTRK inhibitor larotrectinib.

INTRODUCTION: Larotrectinib is an FDA-approved oral small-molecule inhibitor for neurotrophic tropomyosin receptor kinase (NTRK) fusion-positive cancer treatment. Here larotrectinib pharmacokinetic behavior upon co-administration with prototypical inhibitors of the efflux transporters ABCB1/ABCG2 (elacridar), the SLCO1A/1B (OATP1A/1B) uptake transporters (rifampin), and the drug-metabolizing enzyme CYP3A (ritonavir), respectively, was investigated. METHODS: Inhibitors were orally administered prior to oral larotrectinib (10 mg/kg) to relevant genetically modified mouse models. Larotrectinib plasma and tissue homogenate concentrations were measured by a liquid chromatography-tandem mass spectrometric assay. RESULTS: Elacridar increased oral availability (2.7-fold) and markedly improved brain-to-plasma ratios (5.0-fold) of larotrectinib in wild-type mice. Mouse (m)Oatp1a/1b but not hepatic transgenic human (h)OATP1B1 or -1B3 restricted larotrectinib oral availability and affected its tissue distribution. Rifampin enhanced larotrectinib oral availability not only in wild-type mice (1.9-fold), but surprisingly also in Slco1a/1b-/- mice (1.7-fold). Similarly, ritonavir increased the larotrectinib plasma exposure in both wild-type (1.5-fold) and Cyp3a-/- mice (1.7-fold). Intriguingly, both rifampin and ritonavir decreased liver and/or intestinal larotrectinib levels in all related experimental groups, suggesting additional inhibition of enterohepatic Abcb1a/1b activity. CONCLUSIONS: Elacridar enhances both larotrectinib plasma and tissue exposure and especially relative brain penetration, which might be therapeutically relevant. Hepatic mOatp1a/1b but not hOATP1B1 or -1B3 transported larotrectinib. Additionally, rifampin enhances larotrectinib systemic exposure, most likely by inhibiting mOatp1a/1b, but probably also hepatic and/or intestinal mAbcb1. Similar to rifampin, dual-inhibition functions of ritonavir affecting both CYP3A enzymes and enterohepatic Abcb1 transporters enhanced larotrectinib oral availability. The obtained insights may be used to further optimize the clinical-therapeutic application of larotrectinib.

Optimization of dose and route of administration of the P-glycoprotein inhibitor, valspodar (PSC-833) and the P-glycoprotein and breast cancer resistance protein dual-inhibitor, elacridar (GF120918) as dual infusion in rats.

Transporters can play a key role in the absorption, distribution, metabolism, and excretion of drugs. Understanding these contributions early in drug discovery allows for more accurate projection of the clinical pharmacokinetics. One method to assess the impact of transporters in vivo involves co-dosing specific inhibitors. The objective of the present study was to optimize the dose and route of administration of a P-glycoprotein (P-gp) inhibitor, valspodar (PSC833), and a dual P-gp/breast cancer resistance protein (BCRP) inhibitor, elacridar (GF120918), by assessing the transporters' impact on brain penetration and absorption. A dual-infusion strategy was implemented to allow for flexibility with dose formulation. The chemical inhibitor was dosed intravenously via the femoral artery, and a cassette of known substrates was infused via the jugular vein. Valspodar or elacridar was administered as 4.5-hour constant infusions over a range of doses. To assess the degree of inhibition, the resulting ratios of brain and plasma concentrations, Kp's, of the known substrates were compared to the vehicle control. These data demonstrated that doses greater than 0.9 mg/hr/kg valspodar and 8.9 mg/hr/kg elacridar were sufficient to inhibit P-gp- and BCRP-mediated efflux at the blood-brain barrier in rats without any tolerability issues. Confirmation of BBB restriction by efflux transporters in preclinical species allows for subsequent prediction in humans based upon the proteomic expression at rodent and human BBB. Overall, the approach can also be applied to inhibition of efflux at other tissues (gut absorption, liver clearance) or can be extended to other transporters of interest using alternate inhibitors.

Transcriptional regulation of telomeric repeat-containing RNA by acridine derivatives.

Telomere is a specialized DNA-protein complex that plays an important role in maintaining chromosomal integrity. Shelterin is a protein complex formed by six different proteins, with telomeric repeat factors 1 (TRF1) and 2 (TRF2) binding to double-strand telomeric DNA. Telomeric DNA consists of complementary G-rich and C-rich repeats, which could form G-quadruplex and intercalated motif (i-motif), respectively, during cell cycle. Its G-rich transcription product, telomeric repeat-containing RNA (TERRA), is essential for telomere stability and heterochromatin formation. After extensive screening, we found that acridine derivative 2c and acridine dimer DI26 could selectively interact with TRF1 and telomeric i-motif, respectively. Compound 2c blocked the binding of TRF1 with telomeric duplex DNA, resulting in up-regulation of TERRA. Accumulated TERRA could bind with TRF1 at its allosteric site and further destabilize its binding with telomeric DNA. In contrast, DI26 could destabilize telomeric i-motif, resulting in down-regulation of TERRA. Both compounds exhibited anti-tumour activity for A549 cells, but induced different DNA damage pathways. Compound 2c significantly suppressed tumour growth in A549 xenograft mouse model. The function of telomeric i-motif structure was first studied with a selective binding ligand, which could play an important role in regulating TERRA transcription. Our results showed that appropriate level of TERRA transcript could be important for stability of telomere, and acridine derivatives could be further developed as anti-cancer agents targeting telomere. This research increased understanding for biological roles of telomeric i-motif, TRF1 and TERRA, as potential anti-cancer drug targets.

Blood-Brain Barrier Disruption Increases Amyloid-Related Pathology in TgSwDI Mice.

In Alzheimer's disease (AD), several studies have reported blood-brain barrier (BBB) breakdown with compromised function. P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are transport proteins localized at the BBB luminal membrane and play an important role in the clearance of amyloid-ß (Aß). The purpose of this study was to investigate the effect of pharmacological inhibition of Aß efflux transporters on BBB function and Aß accumulation and related pathology. Recently, we have developed an in vitro high-throughput screening assay to screen for compounds that modulate the integrity of a cell-based BBB model, which identified elacridar as a disruptor of the monolayer integrity. Elacridar, an investigational compound known for its P-gp and BCRP inhibitory effect and widely used in cancer research. Therefore, it was used as a model compound for further evaluation in a mouse model of AD, namely TgSwDI. TgSwDI mouse is also used as a model for cerebral amyloid angiopathy (CAA). Results showed that P-gp and BCRP inhibition by elacridar disrupted the BBB integrity as measured by increased IgG extravasation and reduced expression of tight junction proteins, increased amyloid deposition due to P-gp, and BCRP downregulation and receptor for advanced glycation end products (RAGE) upregulation, increased CAA and astrogliosis. Further studies revealed the effect was mediated by activation of NF-κB pathway. In conclusion, results suggest that BBB disruption by inhibiting P-gp and BCRP exacerbates AD pathology in a mouse model of AD, and indicate that therapeutic drugs that inhibit P-gp and BCRP could increase the risk for AD.

Biological assessment of new tetrahydroacridine derivatives with fluorobenzoic moiety in vitro on A549 and HT-29 cell lines and in vivo on animal model.

A new series of tetrahydroacridine derivatives with the fluorobenzoyl moiety was synthesized and evaluated for cytotoxic activity against lung cancer cell lines A549 and colorectal cancer HT29. The cytotoxic activity of the compounds was compared on the somatic cell line-EAhy926. Compounds showed high cytotoxic activity on A549 cells (IC50 183.26-68.07 µM) and HT29 cells (IC50 68.41-19.70 µM), higher than controls-etoposide (IC50 451.47 µM) toward A549 and 5-fluorouracil (IC50 1626.85 µM) against HT29. Derivative 4 was the most cytotoxic to A549, whereas for the cell lines HT29 compound 6. Selected compounds showed similar cytotoxicity to the EAhy926 cell line (IC50 about 50 µM). In the hyaluronidase inhibition assay, all compounds exhibited anti-inflammatory activity, including 4 exhibiting the best inhibitory activity-IC50 of 52.27 µM when the IC50 heparin was 56.41 µM. Mathematical modeling was performed to determine LD50 after intraperitoneal, oral, intravenous and subcutaneous administration and to predict potential mutagenicity and carcinogenicity of the compounds analyzed. Obtained results showed that tested derivatives are slightly toxic compounds, and LD50 values (mg/kg) ranged from 680 to 1200 (oral rat model), the analyzed compounds have low mutagenic potential, and differences between derivatives are insignificant and very low probability of carcinogenicity. To confirm mathematical calculations, an in vivo test was carried out on a laboratory mouse model for two selected compounds. It allowed to qualify compounds: 6 to category 4 of the GHS scale, and 4 to category 3 of the GHS scale.

A new photosafety screening strategy based on in chemico photoreactivity and in vitro skin exposure for dermally-applied chemicals.

This study involved an attempt to establish a new photosafety screening system for dermally-applied chemicals consisting of a reactive oxygen species (ROS) assay and an in vitro skin permeation test. The ROS assay was undertaken to evaluate photoreactivity of six test compounds, acridine (ACD), furosemide (FSM), hexachlorophene (HCP), 8-methoxypsoralen (MOP), norfloxacin (NFX), and promethazine (PMZ), and the in vitro skin permeation test was conducted to obtain steady-state concentration (Css) values of test compounds in removed rat skin. All test compounds were photoreactive based on ROS generation under simulated sunlight exposure. In particular, ROS generation from ACD was high compared with other test compounds, and photoreactivity of ACD was deduced to be potent. The Css values of ACD, HCP, MOP, and PMZ were over 50 µg/mL, and skin exposure to FSM and NFX was found to be extremely low. Upon these findings, ACD was judged to be highly phototoxic. The rank for phototoxic risk of test compounds based on photoreactivity and in vitro skin exposure was mostly in agreement with outcomes on their in vivo phototoxicity in rats. The proposed strategy, an alternative to animal testing, would be efficacious for photosafety evaluation of drug candidates in early stages of pharmaceutical development.

G-quadruplex ligand RHPS4 radiosensitizes glioblastoma xenograft in vivo through a differential targeting of bulky differentiated- and stem-cancer cells.

BACKGROUND: Glioblastoma is the most aggressive and most lethal primary brain tumor in the adulthood. Current standard therapies are not curative and novel therapeutic options are urgently required. Present knowledge suggests that the continued glioblastoma growth and recurrence is determined by glioblastoma stem-like cells (GSCs), which display self-renewal, tumorigenic potential, and increased radio- and chemo-resistance. The G-quadruplex ligand RHPS4 displays in vitro radiosensitizing effect in GBM radioresistant cells through the targeting and dysfunctionalization of telomeres but RHPS4 and Ionizing Radiation (IR) combined treatment efficacy in vivo has not been explored so far. METHODS: RHPS4 and IR combined effects were tested in vivo in a heterotopic mice xenograft model and in vitro in stem-like cells derived from U251MG and from four GBM patients. Cell growth assays, cytogenetic analysis, immunoblotting, gene expression and cytofluorimetric analysis were performed in order to characterize the response of differentiated and stem-like cells to RHPS4 and IR in single and combined treatments. RESULTS: RHPS4 administration and IR exposure is very effective in blocking tumor growth in vivo up to 65 days. The tumor volume reduction and the long-term tumor control suggested the targeting of the stem cell compartment. Interestingly, RHPS4 treatment was able to strongly reduce cell proliferation in GSCs but, unexpectedly, did not synergize with IR. Lack of radiosensitization was supported by the GSCs telomeric-resistance observed as the total absence of telomere-involving chromosomal aberrations. Remarkably, RHPS4 treatment determined a strong reduction of CHK1 and RAD51 proteins and transcript levels suggesting that the inhibition of GSCs growth is determined by the impairment of the replication stress (RS) response and DNA repair. CONCLUSIONS: We propose that the potent antiproliferative effect of RHPS4 in GSCs is not determined by telomeric dysfunction but is achieved by the induction of RS and by the concomitant depletion of CHK1 and RAD51, leading to DNA damage and cell death. These data open to novel therapeutic options for the targeting of GSCs, indicating that the combined inhibition of cell-cycle checkpoints and DNA repair proteins provides the most effective means to overcome resistance of GSC to genotoxic insults.

Detection and Differentiation of Breast Cancer Sub-Types using a cPLA2α Activatable Fluorophore.

Cytosolic phospholipase A2α (cPLA2α) has been shown to be elevated in breast cancer and is a potential biomarker in the differentiation of molecular sub-types. Using a cPLA2α activatable fluorophore, DDAO arachidonate, we explore its ability to function as a contrast agent in fluorescence-guided surgery. In cell lines ranging in cPLA2α expression and representing varying breast cancer sub-types, we show DDAO arachidonate activates with a high correlation to cPLA2α expression level. Using a control probe, DDAO palmitate, in addition to cPLA2α inhibition and genetic knockdown, we show that this activation is a result of cPLA2α activity. In mouse models, using an ex vivo tumor painting technique, we show that DDAO arachidonate activates to a high degree in basal-like versus luminal-like breast tumors and healthy mammary tissue. Finally, we show that using an in vivo model, orthotopic basal-like tumors give significantly high probe activation compared to healthy mammary fat pads and surrounding tissue. Together we conclude that cPLA2α activatable fluorophores such as DDAO arachidonate may serve as a useful contrast agent for the visualization of tumor margins in the fluorescence-guided surgery of basal-like breast cancer.

Post-treatment with JP-1302 protects against renal ischemia/reperfusion-induced acute kidney injury in rats.

Ischemia/reperfusion injury is the most common cause of acute kidney injury. We previously revealed that pre-treatment with yohimbine or JP-1302 attenuated renal ischemia/reperfusion injury by inhibition of α2C-adrenoceptor antagonist. The aim of the present study is to investigate the effects of post-treatment with JP-1302 on renal ischemia/reperfusion injury in rats. Male Sprague Dawley rats were randomly divided into four groups: sham operation, ischemia/reperfusion, pre-treatment with JP-1302 (3.0 mg/kg) and post-treatment with JP-1302 groups. In ischemia/reperfusion injury, renal functional parameters, such as blood urea nitrogen, plasma creatinine and creatinine clearance, deteriorated after reperfusion. Renal venous norepinephrine concentrations, as well as inflammatory molecules in the kidney increased after reperfusion. Both pre- and post-treatment with JP-1302 improved renal dysfunction, tissue damage, renal venous norepinephrine concentrations and inflammatory molecules expression in the kidney. In conclusion, these results suggest that post-treatment with JP-1302 protects on ischemia/reperfusion-induced acute kidney injury by suppressing cytokine upregulation via α2C-adrenoceptors.

Oral coadministration of elacridar and ritonavir enhances brain accumulation and oral availability of the novel ALK/ROS1 inhibitor lorlatinib.

Lorlatinib, a novel generation oral anaplastic lymphoma kinase (ALK) and ROS1 inhibitor with high membrane and blood-brain barrier permeability, recently received accelerated approval for treatment of ALK-rearranged non-small-cell lung cancer (NSCLC), and its further clinical development is ongoing. We previously found that the efflux transporter P-glycoprotein (MDR1/ABCB1) restricts lorlatinib brain accumulation and that the drug-metabolizing enzyme cytochrome P450-3A (CYP3A) limits its oral availability. Using genetically modified mouse models, we investigated the impact of targeted pharmacological inhibitors on lorlatinib pharmacokinetics and bioavailability. Upon oral administration of lorlatinib, the plasma AUC0-8h in CYP3A4-humanized mice was ∼1.8-fold lower than in wild-type and Cyp3a-/- mice. Oral coadministration of the CYP3A inhibitor ritonavir caused reversion to the AUC0-8h levels seen in wild-type and Cyp3a-/- mice, without altering the relative tissue distribution of lorlatinib. Moreover, simultaneous pharmacological inhibition of P-glycoprotein and CYP3A4 with oral elacridar and ritonavir in CYP3A4-humanized mice profoundly increased lorlatinib brain concentrations, but not its oral availability or other relative tissue distribution. Oral lorlatinib pharmacokinetics was not significantly affected by absence of the multispecific Oatp1a/1b drug uptake transporters. The absolute oral bioavailability of lorlatinib over 8 h in wild-type, Cyp3a-/-, and CYP3A4-humanized mice was 81.6%, 72.9%, and 58.5%, respectively. Lorlatinib thus has good oral bioavailability, which is markedly restricted by human CYP3A4 but not by mouse Cyp3a. Pharmacological inhibition of CYP3A4 reversed these effects, and simultaneous P-gp inhibition with elacridar boosted absolute brain levels of lorlatinib by 16-fold without obvious toxicity. These insights may help to optimize the clinical application of lorlatinib.

pH and thermo dual stimulus-responsive liposome nanoparticles for targeted delivery of platinum-acridine hybrid agent.

The complexes of the type [PtCl(L2)(ACRAMTU)](NO3)2 (ACRAMTU = 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea) were synthesized: PT-ACRAMTU (1), L2 = ethane-1,2-diamine (en); PT(dach)-ACRAMTU (2), L2 = (1R,2R)-1,2-diaminocyclohexane (dach); PT(pda-OH)-ACRAMTU (3), L2 = 2-hydroxy-1,3-propanediamine (pda-OH). The complexes containing diverse diamines exhibit different DNA binding capacity and cytotoxicity. Complex 3 shows excellent capability not only on the strongest non-cisplatin-type DNA damage, but also superior anticancer activity in NCI-H460 cells (IC50 = 0.23 ±â€¯0.05 µM). For overcoming water insolubly and side effects, we encapsulated complex 3 into liposomes. PT@NPs were characterized in terms of particle size, morphology, drug loading capacity (DLC), encapsulation efficiency (EE) and stability. In vitro triggered release showed that the release of the platinum drug was steerable and the release rate was fast under low pH (<7.0) and high temperature (>Tm = 41 °C). PT@NPs showed significant inhibitory effect in NCI-H460 cells. Flow cytometry analysis indicates G0/G1 phase arrest of cells treated with complex 3, whereas cells treated with cisplatin progress to G2/M of the cell cycle. The mechanistic differences validate that complex 3 is a potent anticancer agent superior than current clinical platinum-based therapies. PT@NPs have the potential in drug delivery systems (DDS) for non-small cell lung cancer (NSCLC) therapy.

Codelivery of doxorubicin and elacridar to target both liver cancer cells and stem cells by polylactide-co-glycolide/d-alpha-tocopherol polyethylene glycol 1000 succinate nanoparticles.

PURPOSE: Liver cancer is the third leading cause of cancer-related deaths worldwide. Liver cancer stem cells (LCSCs) are a subpopulation of cancer cells that are responsible for the initiation, progression, drug resistance, recurrence, and metastasis of liver cancer. Recent studies have suggested that the eradication of both LCSCs and liver cancer cells is necessary because the conversion of cancer stem cells (CSCs) to cancer cells occasionally occurs. As ATP-binding cassette (ABC) transporters are overexpressed in both CSCs and cancer cells, combined therapies using ABC transporter inhibitors and chemotherapy drugs could show superior therapeutic efficacy in liver cancer. In this study, we developed poly(lactide-co-glycolide)/d-alpha-tocopherol polyethylene glycol 1000 succinate nanoparticles to accomplish the simultaneous delivery of an optimized ratio of doxorubicin (DOX) and elacridar (ELC) to target both LCSCs and liver cancer cells. METHODS: Median-effect analysis was used for screening of DOX and ELC for synergy in liver cancer cells (HepG2 cells) and LCSCs (HepG2 tumor sphere [HepG2-TS]). Then, nanoparticles loaded with DOX and ELC at the optimized ratio (NDEs) were prepared by nanoprecipitation method. The cytotoxicity and colony and tumor sphere formation ability of nanoparticles were investigated in vitro, and the tissue distribution and antitumor activity of nanoparticles were evaluated in vivo. RESULTS: We demonstrated that a DOX/ELC molar ratio of 1:1 was synergistic in HepG2 cells and HepG2-TS. NDEs were shown to exhibit significantly increased cytotoxic effects against both HepG2 and HepG2-TS compared with DOX-loaded nanoparticles (NDs) or ELC-loaded nanoparticles (NEs) in vitro. In vivo studies demonstrated that the nanoparticles exhibited better tumor targeting, with NDE showing the strongest antitumor activity with lower systemic toxicity. CONCLUSION: These results suggested that NDE represented a promising combination therapy against liver cancer by targeting both liver cancer cells and CSCs.

ß-Casein micelles for oral delivery of SN-38 and elacridar to overcome BCRP-mediated multidrug resistance in gastric cancer.

Gastric cancer is the third leading cause of cancer-related mortality worldwide. A dominant hindrance towards curative cancer therapy is multidrug resistance (MDR) mediated by ATP-dependent efflux pumps. We have previously demonstrated the ability of ß-casein (ß-CN) micelles and re-assembled casein micelles to serve as nanovehicles for oral delivery and target-activated release of hydrophobic chemotherapeutics in the stomach, and to overcome P-glycoprotein-dependent MDR in gastric cancer. Herein we investigated the modularity and versatility of this ß-CN-based delivery system using a different synergistic drug duo to treat MDR gastric cancer cells overexpressing the breast cancer resistance protein (BCRP). The chemotherapeutic drug SN-38, a BCRP transport substrate, and the BCRP efflux transport inhibitor, elacridar, exhibited high binding affinity to ß-CN, as demonstrated by spectrophotometry and spectrofluorometry. Furthermore, light microscopy and dynamic light scattering confirmed that ß-CN solubilized these drugs and suppressed drug crystal growth. In vitro cytotoxicity against MDR human gastric carcinoma cells overexpressing BCRP revealed a synergistic activity of this drug combination and a complete MDR reversal. Hence, our findings highlight the great promise of casein-based nanovehicles, harboring hydrophobic synergistic drug combinations, as a modular and versatile oral delivery system for local drug release in the stomach to overcome chemoresistance in gastric cancer.

Impact of P-Glycoprotein on Intestinal Absorption of an Inhibitor of Apoptosis Protein Antagonist in Rats: Mechanisms of Nonlinear Pharmacokinetics and Food Effects.

PURPOSE: This study was designed to investigate the effects of P-glycoprotein (P-gp) expressed in the intestine on the nonlinear pharmacokinetics (PK) of T-3256336, an inhibitor of apoptosis protein inhibitor, and food effects on its bioavailability in rats. METHODS: To investigate the factors that contribute to nonlinear PK of T-3256336 in the intestine and liver, rats double-cannulated in the portal vein and femoral artery (PS rats) were used. FaFg (Fa, absorption ratio; Fg, intestinal availability) and hepatic availability (Fh) were simultaneously evaluated based on the difference between the portal and systemic blood area under the concentration-time curve (AUC). Elacridar was used as a P-gp inhibitor to assess the impact of P-gp on the intestinal absorption. RESULTS: After oral administration of T-3256336 to PS rats at 3 and 30 mg/kg, FaFg value increased with dose escalation, whereas Fh value was nearly constant. Moreover, co-administration of elacridar resulted in a 5-fold increase in the FaFg value at 3 mg/kg. The AUC value of T-3256336 under fed conditions was 3-fold lower than that under fasted conditions. This food effect on the oral bioavailability (BA) was reduced by concomitant administration of elacridar. CONCLUSION: P-gp expressed in the intestine would cause nonlinear PK and a food effect on BA of T-3256336 in rats.

Intravenous infusion for the controlled exposure to the dual ABCB1 and ABCG2 inhibitor elacridar in nonhuman primates.

Elacridar (GF120918) is a highly potent inhibitor of both P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2), the main efflux transporters expressed at the blood-brain barrier (BBB). Elacridar shows very low aqueous solubility, which complicates its formulation for i.v. administration. An intravenous infusion protocol would be preferred to achieve high and controlled plasma concentrations of elacridar in large animals, including nonhuman primates. Formulation of elacridar for i.v. infusion was achieved using a co-solvent strategy, resulting in an aqueous dispersion with a final concentration of 5 g L-1 elacridar with tetrahydrofuran (5% w/v) in aqueous D-glucose solution (2.5%, w/v). Particle size (mean = 2.8 ± 0.9 µm) remained stable for 150 min. The preparation was i.v. administered as a continuous infusion (12 mg kg-1 h-1 for 90 min) to three baboons. Arterial and venous plasma pharmacokinetics (PK) of elacridar were monitored using a newly developed and validated HPLC-UV method. Elacridar concentration increased rapidly to reach a plateau at 9.5 µg mL-1 within 20 min after the start of infusion. Elacridar PK in venous plasma did not differ from arterial plasma facing the BBB, indicating the absence of an arteriovenous concentration gradient. Intravenous infusion of elacridar allows for controlled exposure of the BBB and offers a useful tool to assess the impact of ABCB1/ABCG2 on drug disposition to the brain in nonhuman primates, a relevant animal model for the study of transporter function at the BBB.

Incorporation of lipolysis in monolayer permeability studies of lipid-based oral drug delivery systems.

Lipid-based drug delivery systems, a well-tolerated class of formulations, have been evaluated extensively to enhance the bioavailability of poorly soluble drugs. However, it has been difficult to predict the in vivo performance of lipid dosage forms based on conventional in vitro techniques such as cell monolayer permeability studies because of the complexity of the gastrointestinal processing of lipid formulations. In the current study, we explored the feasibility of coupling Caco-2 and Madin-Darby canine kidney monolayer permeability studies with lipolysis, a promising in vitro technique to evaluate lipid systems. A self-emulsifying lipid delivery system was formulated using a blend of oil (castor oil), surfactant (Labrasol® or PL497), and co-surfactant (lecithin). Formulations demonstrating high drug solubility and rapid self-emulsification were selected to study the effect of lipolysis on in vitro cell permeability. Lipolysis of the formulations was carried out using pancreatin as the digestive enzyme. All the digested formulations compromised monolayer integrity as indicated by lowered trans-epithelial electrical resistance (TEER) and enhanced Lucifer yellow (LY) permeability. Further, the changes in TEER value and LY permeability were attributable to the digestion products of the formulation rather than the individual lipid excipients, drug, digestion enzyme, or the digestion buffer. The digested formulations were fractionated into pellet, oily phase, and aqueous phase, and the effect of each of these on cell viability was examined. Interestingly, the aqueous phase, which is considered important for in vivo drug absorption, was responsible for cytotoxicity. Because lipid digestion products lead to disruption of cell monolayer, it may not be appropriate to combine lipolysis with cell monolayer permeability studies. Additional in vivo studies are needed to determine any potential side effects of the lipolysis products on the intestinal permeability barrier, which could determine the suitability of lipid-based systems for oral drug delivery.

[Clinical efficacy of the immunomodulatory agent cycloferon (tablets) in viral respiratory infections: Results of a systematic review and meta-analysis]. / Klinicheskaia éffektivnost' immunomoduliatora tsikloferona (tabletki) pri virusnykh infektsiiakh organov dykhaniia: rezul'taty sistematicheskogo obzora i metaanaliza.

The authors carried out a systematic review and subsequent meta-analysis of randomized clinical trials evaluating the efficacy of the immunomodulator agent cycloferon as tablets in adults and children with viral respiratory diseases. A total estimate of its clinical efficacy was obtained in terms of compared heterogeneous groups and response variables. The data published in 16 articles were used to calculate the formal parameters of the clinical efficacy of cycloferon (increased absolute and relative benefits, odds ratio (OR); the number of patients needed to be additionally treated with cycloferon to achieve a favorable outcome or to prevent a poor outcome in one patient, etc.). High heterogeneity hampered the unequivocal interpretation of results; however, combining the compared homogeneous groups in the meta-analysis (with adjustments for fixed and random effects) increased the statistical power of the investigation. In children aged 6 to 18 years, the OR for the positive effect of the drug (no new cases after its preventive administration) was 5.3 (95% confidence interval (CI), 4.8-5.9), heterogeneity test, χ2 = 249.5; p=0.000...; I2 = 94.8% (95% CI, 92.7-96.3%). This suggested the heterogeneity of clinical trial data and extrapolated this estimate to medical practice. The use of cycloferon in adults to treat acute respiratory viral infection enhanced their chances of enduring the disease in a mild form and avoiding serious complications: the OR for positive outcomes was 9.7 (95% CI, 7.0-13.0), while the effect was more homogeneous than in children (heterogeneity test, χ2 = 7.4; p=0.061...; I2 = 59.4% (95% CI, 0-86.5). Thus, the use of cycloferon to treat and prevent acute viral respiratory infections showed a more than 5-fold increase in the probability of avoiding the disease or enduring the latter in a mild form.

Highly Eribulin-resistant KBV20C Oral Cancer Cells Can Be Sensitized by Co-treatment with the Third-generation P-Glycoprotein Inhibitor, Elacridar, at a Low Dose.

BACKGROUND/AIM: Eribulin mesylate, also called Halaven® (HAL), was recently developed as a microtubule-targeting drug and is used in the clinic for resistant or metastatic cancer. Previously, we showed that P-glycoprotein (P-gp)-overexpressing KBV20C oral cancer cells are highly resistant to HAL compared to sensitive KB cells. This qualitative study was designed to identify specific P-gp inhibitors that increase the sensitivity of highly resistant cancer cells to HAL. MATERIALS AND METHODS: In order to identify functional P-gp inhibitors, HAL-treated KBV20C cells were co-treated with P-gp inhibitors, verapamil, elacridar, cyclosporine A, mitotane, piperine, fumagillin, curcumin, indomethacin, probenecid, sulindac, tesmilifene, and C-4. We then evaluated which P-gp inhibitors required a low dose to sensitize KBV20C cells to HAL. We also determined whether a low dose of a P-gp inhibitor could inhibit P-gp efflux pumping. RESULTS: We found that cyclosporine A sensitized HAL-treated KBV20C cells at a low dose, whereas verapamil, another first-generation P-gp inhibitor, required a dose that was nearly 10-fold higher. We also found that the natural products, piperine and mitotane, sensitized KBV20C cells to HAL co-treatment. Interestingly, we found that elacridar, a third-generation P-gp inhibitor, sensitized HAL-treated cells at a low dose. Elacridar required approximately a 500-fold lower dose than that of verapamil to exert a similar effect. All inhibitors showed P-gp inhibitory activity that correlated with sensitivity to HAL. CONCLUSION: These results suggest that highly HAL-resistant cancer cells can be sensitized with cyclosporine A or elacridar, specific P-gp inhibitors that exert their effects at a low dose. These findings provide important information regarding the sensitization of highly HAL-resistant cells with selective P-gp inhibitors and indicate that elacridar may be used to treat such highly HAL-resistant cancer cells.

Novel tetrahydroacridine and cyclopentaquinoline derivatives with fluorobenzoic acid moiety induce cell cycle arrest and apoptosis in lung cancer cells by activation of DNA damage signaling.

Lung cancer is still the leading cause of cancer-related death worldwide, indicating a necessity to develop more effective therapy. Acridine derivatives are potential anticancer agents due to their ability to intercalate DNA as well as inhibit enzymes involved in replication and transcription. Recently, we have evaluated anticancer activity of 32 novel acridine-based compounds. We found that the most effective were tetrahydroacridine and cyclopentaquinoline derivatives with fluorobenzoic acid containing eight and nine carbon atoms in the aliphatic chain. The aim of this study was to determine the molecular mechanisms of compounds-induced cell cycle arrest and apoptosis in human lung adenocarcinoma cells. All compounds activated Ataxia telangiectasia mutated kinase and phosphorylated histone H2A.X at Ser139 indicating DNA damage. Treatment of cells with the compounds increased phosphorylation and accumulation of p53 that regulate cell cycle as well as apoptosis. All compounds induced G0/1 cell cycle arrest by phosphorylation of cyclin-dependent kinase 2 at Tyr15 resulting in attenuation of the kinase activity. In addition, cyclopentaquinoline derivatives induced expression of cyclin-dependent kinase 2 inhibitor, p21; however, tetrahydroacridine derivatives had no significant effect on p21. Moreover, all compounds decreased the mitochondrial membrane potential accompanied by increased expression of Bax and down-regulation of Bcl-2, suggesting activation of the mitochondrial pathway. All compounds also significantly attenuated the migration rates of lung cancer cells. Collectively, our findings suggest a central role of activation of DNA damage signaling in response to new acridine derivatives treatment to induce cell cycle arrest and apoptosis in cancer cells and provide support for their further development as potential drug candidates.