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IHL-305 is a PEGylated liposomal formulation of irinotecan (CPT-11). The objective of this study was to evaluate the factors associated with interpatient variability in the pharmacokinetics and pharmacodynamics of IHL-305 in patients with advanced solid tumors. IHL-305 was administered intravenously once every 4 weeks as part of a Phase I study. Pharmacokinetic studies of the liposomal sum total CPT-11, released CPT-11, SN-38, SN-38G, 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]-carbonyloxycamptothecin, and 7-ethyl-10-[4-amino-1-piperidino]-carbonyloxycamptothecin in plasma were performed. Noncompartmental and compartmental pharmacokinetic analyses were conducted using pharmacokinetic data for sum total CPT-11. The pharmacokinetic variability of IHL-305 is associated with linear and nonlinear clearance. Patients whose age and body composition (ratio of total body weight to ideal body weight [TBW/IBW]) were greater than the median age and TBW/IBW of the study had a 1.7-fold to 2.6-fold higher ratio of released CPT-11 area under the concentration versus time curve (AUC) to sum total CPT-11 AUC. Patients aged

A pharmacokinetic model was constructed to explain the difference in brain- and cerebrospinal fluid (CSF)-to-plasma and brain-to-CSF unbound drug concentration ratios (Kp,uu,brain, Kp,uu,CSF, and Kp,uu,CSF/brain, respectively) of drugs under steady-state conditions in rats. The passive permeability across the blood-brain barrier (BBB), PS1, was predicted by two methods using log(D/molecular weight(0.5)) for PS1(1) or the partition coefficient in octanol/water at pH 7.4 (LogD), topologic van der Waals polar surface area, and van der Waals surface area of the basic atoms for PS1(2). The coefficients of each parameter were determined using previously reported in situ rat BBB permeability. Active transport of drugs by P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) measured in P-gp- and Bcrp-overexpressing cells was extrapolated to in vivo by introducing scaling factors. Brain- and CSF-to-plasma unbound concentration ratios (Kp,uu,brain and Kp,uu,CSF, respectively) of 19 compounds, including P-gp and Bcrp substrates (daidzein, dantrolene, flavopiridol, genistein, loperamide, quinidine, and verapamil), were simultaneously fitted to the equations in a three-compartment model comprising blood, brain, and CSF compartments. The calculated Kp,uu,brain and Kp,uu,CSF of 17 compounds were within a factor of three of experimental values. Kp,uu,CSF values of genistein and loperamide were outliers of the prediction, and Kp,uu,brain of dantrolene also became an outlier when PS1(2) was used. Kp,uu,CSF/brain of the 19 compounds was within a factor of three of experimental values. In conclusion, the Kp,uu,CSF/brain of drugs, including P-gp and Bcrp substrates, could be successfully explained by a kinetic model using scaling factors combined with in vitro evaluation of P-gp and Bcrp activities.

We previously identified dibenzooxepine derivative 1 as a potent PPARγ ligand with a unique binding mode owing to its non-thiazolidinedione scaffold. However, while 1 showed remarkably potent MKN-45 gastric cancer cell aggregation activity, an indicator of cancer differentiation-inducing activity induced by PPARγ activation, we recognized that 1 was metabolically unstable. In the present study, we identified a metabolically soft spot, and successfully discovered 3-fluoro dibenzooxepine derivative 9 with better metabolic stability. Further optimization provided imidazo[1,2-a]pyridine derivative 17, which showed potent MKN-45 gastric cancer cell aggregation activity and excellent PK profiles compared with 9. Compound 17 exerted a growth inhibitory effect on AsPC-1/AG1 pancreatic tumor in mice. Furthermore, the decrease in the hematocrit (an indicator of localized edema, a serious adverse effect of PPARγ ligands) was tolerable even with oral administration at 200 mg/kg in healthy mice.

To investigate pharmacokinetics (PK) of encapsulated CPT-11, released CPT-11 and the active metabolite SN-38 following administration of IHL-305 and to identify factors that may influence IHL-305 PK.Plasma samples from 39 patients with solid tumors were collected in a phase I study. IHL-305 was administered as a 1 h IV infusion with doses ranging from 3.5 to 210 mg/m(2). Plasma concentrations of encapsulated CPT-11, released CPT-11 and SN-38 were used to develop a population PK model using NONMEM®.PK of encapsulated CPT-11 was described by 1-compartment model with nonlinear clearance and PK of released CPT-11 was described by a 1-compartment model with linear clearance for all patients. PK of the active metabolite SN-38 was described by a 2-compartment model with linear clearance for all patients. Covariate analysis revealed that gender was a significant covariate for volume of distribution of encapsulated CPT-11. Vencap in male patients is 1.5-fold higher compared with female patients.The developed population PK modeling approach is useful to predict PK exposures of encapsulated and released drug and can be applied to the more than 300 other nanoparticle formulations of anticancer agents that are currently in development. The effect of gender on PK of IHL-305 needs to be further evaluated.

IHL-305 is a novel PEGylated liposome containing irinotecan. This study examined the safety profile and pharmacokinetics of IHL-305 and established the maximum tolerated dose and recommended phase II dose (RP2D). In a standard 3 + 3 design, IHL-305 was administered IV on day 1 of a 28-day treatment schedule. Subsequently, a 14-day treatment schedule was also explored. Two patient populations were evaluated separately: Patients with at least one wild-type (wt) allele of UGT1A1 (UDP glucoronosyltransferase 1A1) wt/wt or wt/*28 as one group (referred to as UGT1A1 wt group) and patients with UGT1A1*28 homozygous variant (*28/*28) as another group. Sixty patients were treated: 42 on the 28-day schedule and 18 on the 14-day schedule. Seven patients were homozygous variant (*28/*28). In the UGT1A1 wt group, the MTD and RP2D of IHL-305 was 160 mg/m2 every 28 days and 80 mg/m2 every 14 days. DLTs included nausea, vomiting, diarrhea, and neutropenia. The most common adverse events were nausea (75 %), vomiting (52 %), diarrhea (62 %), anorexia (57 %), and fatigue (57 %). At the MTD for both schedules, IHL-305 administration resulted in a high and prolonged exposure of sum total irinotecan, released irinotecan, and SN-38 in plasma. One partial response was observed in a patient with breast cancer and eight patients had stable disease for >6 months. IHL-305, a novel preparation of irinotecan encapsulated in liposomes, can be safely given to patients in a repeated fashion on a 4- or 2-week dosing schedule.

We have developed a novel and potent chemical series of 5,5-diphenylpentadienamides for targeting TRPV1 in vitro and in vivo. In this investigation, we examined a variety of replacements for the 5-position of dienamides with the goal of addressing issues related to pharmacokinetics. Our data suggest that substitution with alkoxy groups on the phenyl ring at the 5-position increases their ability to penetrate the blood-brain barrier. This investigation culminated in the discovery of compound (R)-36b, which showed a good pharmacokinetic profile. In vivo, compound (R)-36b was found to be effective at reversing mechanical allodynia in rats in a dose-dependent manner, and it reversed thermal hyperalgesia in a model of neuropathic pain induced by sciatic nerve injury.

Species differences in the pharmacokinetics of KW-7158 [(2S)-(+)-3,3,3-Trifluoro-2-hydroxy-2-methyl-N-(5,5,10-trioxo-4,10-dihydrothieno[3,2-c][1]benzothiepin-9-yl)propanamide] were studied in in vivo and in vitro experiments. The exposure ratio of hydrolyzed metabolite (M2, primary metabolite in human plasma)/KW-7158 was higher than the ratio of thiophen-to-furan converted metabolite (M1)/KW-7158 in human subjects after oral administration, but the mouse, rat and dog studies gave opposite results. M2 was produced in the highest amount by the 9000g supernatant of small intestine, followed by that of liver and kidney in human subjects. After correction for protein contents, the results obtained suggested that the small intestine plays a major role in the metabolism to M2 for the first pass effect after oral administration of KW-7158. The formation of M2 was independent of the presence of NADPH and was inhibited by various esterase inhibitors. These observations suggested that the predominant enzymes or isozymes involved in the formation of M2 are esterases, which differ between humans and animals. Such differences may be one of the reasons for the species differences in the pharmacokinetics of KW-7158 between humans and animals.

Huali Wu,1 Jeffrey R Infante,2 Vicki L Keedy,3 Suzanne F Jones,2 Emily Chan,3 Johanna C Bendell,2 Wooin Lee,4 Whitney P Kirschbrown,1 Beth A Zamboni,5 Satoshi Ikeda,6 Hiroshi Kodaira,6 Mace L Rothenberg,3 Howard A Burris III,2 William C Zamboni1,7–9 1UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, 2Sarah Cannon Research Institute/Tennessee Oncology, PLLC, 3Vanderbilt University, Nashville, TN, 4Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington,KY, 5Department of Mathematics, Carlow University, Pittsburgh, PA,USA; 6Yakult Honsha Co., Ltd., Medical Development Department, Tokyo, Japan; 7UNC Lineberger Comprehensive Cancer Center, 8UNCInstitute for Pharmacogenomics and Individualized Therapy, 9Carolina Center for Cancer Nanotechology Excellence, University of North Carolina, Chapel Hill, NC, USA Abstract: IHL-305 is a PEGylated liposomal formulation of irinotecan (CPT-11). The objective of this study was to evaluate the factors associated with interpatient variability in the pharmacokinetics and pharmacodynamics of IHL-305 in patients with advanced solid tumors. IHL-305 was administered intravenously once every 4 weeks as part of a Phase I study. Pharmacokinetic studies of the liposomal sum total CPT-11, released CPT-11, SN-38, SN-38G, 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]-carbonyloxycamptothecin, and 7-ethyl-10-[4-amino-1-piperidino]-carbonyloxycamptothecin in plasma were performed. Noncompartmental and compartmental pharmacokinetic analyses were conducted using pharmacokinetic data for sum total CPT-11. The pharmacokinetic variability of IHL-305 is associated with linear and nonlinear clearance. Patients whose age and body composition (ratio of total body weight to ideal body weight [TBW/IBW]) were greater than the median age and TBW/IBW of the study had a 1.7-fold to 2.6-fold higher ratio of released CPT-11 area under the concentration versus time curve (AUC) to sum total CPT-11 AUC. Patients aged

Purpose: In this study, to optimize the polymeric drug delivery system for cancer chemotherapy, we developed a new pH-sensitive polymeric carrier, poly(vinylpyrrolidone-co-dimethylmaleic anhydride) [PVD], that could gradually release native form of drugs with full activity, from the conjugates in response to changes in pH. We examined the usefulness of PVD as a polymeric drug carrier. Experimental Design: PVD was radically synthesized with vinylpyrrolidone and 2,3-dimethylmaleic anhydride, which is known to be a pH-reversible amino-protecting reagent. Conjugates between PVD and other drugs, such as Adriamycin (ADR), were prepared under the slightly basic conditions (pH 8.5). The drug-release pattern and the antitumor activity of PVD were examined. Results: At pH 8.5, the release of the drugs from the conjugate was not observed. In contrast, PVD could release fully active drugs in the native form in response to the change in pH near neutrality, and gradually released drugs at neutral pH (7.0) and slightly acidic pH (6.0). The drug-release pattern in serum was almost similar to that observed during these physiological conditions. The PVD-conjugated ADR showed superior antitumor activity against sarcoma-180 solid tumor in mice, and it had less toxic side effects than free ADR. This enhancement in the antitumor therapeutic window may be due to not only the improvement of plasma half-lives and tumor accumulation of ADR, but also its controlled and sustained release from the conjugates in vivo. Conclusions: These results indicate that PVD is an effective polymeric carrier for optimizing cancer therapy.

The objective of this study was to elucidate the range of abilities of nonclinical safety assessment for predicting adverse drug reactions (ADRs) in humans. The dataset included 1256 ADRs with an incidence rate of 5% or more collected from 142 drugs approved in Japan from 2001 to 2010 (excluding anticancer agents and vaccines). Gastrointestinal, neurological and hepatobiliary ADRs were relatively common, followed by hematological, cutaneous, systemic and cardiovascular ADRs in the dataset. The analysis revealed that 48% of ADRs were predictable based on a comprehensive nonclinical safety assessment considering animal toxicity. Hematological and ocular ADRs, infection, and application site reactions showed a correlation of more than 70%, while musculoskeletal, respiratory and neurological ADRs showed a correlation of less than 30%. In addition to subjective patient perceptions, several laboratory parameters routinely monitored both in animals and humans showed a lower correlation, e.g., abnormalities in hepatobiliary and metabolic parameters, and blood pressure increase. Large molecule drugs showed lower correlation than small molecule drugs; ADRs were observed in various organs and consideration of pharmacological action did not significantly contribute to the prediction. It was also confirmed that the current standard of toxicology testing regarding dosing duration and dose level is adequate to detect concordant animal toxicity. This study collectively demonstrated a significant value of nonclinical safety assessment in predicting ADRs in humans. It also identified the subset of ADRs with poor predictability, highlighting the need for advanced testing that enables successful translation of animal toxicity to clinical settings with better accuracy and sensitivity.

This study investigated the impact of the active efflux mediated by P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) at the blood-brain barrier (BBB) on the predictability of the unbound brain concentration (C(u,brain)) by the concentration in the cerebrospinal fluid (CSF) (C(u,CSF)) in rats. C(u,brain) is obtained as the product of the total brain concentration and unbound fraction in the brain (f(u,brain)) determined in vitro in brain slices. Twenty-five compounds, including P-gp and/or Bcrp substrates, were given a constant intravenous infusion, and their plasma, brain, and CSF concentrations were determined. P-gp and/or Bcrp substrates, such as verapamil, loperamide, flavopiridol, genistein, quinidine, dantrolene, daidzein, cimetidine, and pefloxacin, showed a higher CSF-to-brain unbound concentration ratio (K(p,uu,CSF/brain)) compared with non-P-gp and non-Bcrp substrates. K(p,uu,CSF/brain) values of P-gp-specific (quinidine and verapamil) and Bcrp-specific (daidzein and genistein) substrates were significantly decreased in Mdr1a/1b(-/-) and Bcrp(-/-) mice, respectively. Furthermore, consistent with the contribution of P-gp and Bcrp to the net efflux at the BBB, K(p,uu,CSF/brain) values of the common substrates (flavopiridol and erlotinib) were markedly decreased in Mdr1a/1b(-/-)/Bcrp(-/-) mice, but only moderately or weakly in Mdr1a/1b(-/-) mice and negligibly in Bcrp(-/-) mice. In conclusion, predictability of C(u,brain) by C(u,CSF) decreases along with the net transport activities by P-gp and Bcrp at the BBB. C(u,CSF) of non-P-gp and non-Bcrp substrates can be a reliable surrogate of C(u,brain) for lipophilic compounds.

The antitumor effect of IHL-305, a novel pegylated liposome containing irinotecan, was investigated in human xenograft models. After subcutaneous transplantation of several human cancer cell lines (colorectal, non-small cell lung, small cell lung, prostate, ovarian and gastric cancer cells) to nude mice, IHL-305 or CPT-11 was administered intravenously 3 times at 4-day intervals. In all xenograft models tested, IHL-305 showed superior antitumor activity to that of CPT‑11 and a comparable tumor-growth-inhibitory effect at one-eighth or less of the dose of CPT-11, even against HT-29 colorectal and NCI-H460 non-small cell lung cancer cell lines, which show intrinsic resistance to CPT-11. A single injection or 2 injections of IHL-305 on several dosing schedules also resulted in a significant antitumor effect compared to that of vehicle control in a dose-dependent manner and showed comparable antitumor activity at about one-fifth the dose of the maximum tolerated dose of CPT-11. The analysis of the concentrations of irinotecan and SN-38, an active metabolite of CPT-11, in plasma and tumors revealed that irinotecan was maintained at high concentrations, and the prolonged presence of SN-38 in plasma and tumors in IHL-305 treated mice compared with CPT-11-treated mice. Therefore, the stronger tumor inhibitory effect of IHL-305, as compared to CPT-11, was associated with the difference in the concentration of irinotecan in plasma or tumors after each agent was administered and with the maintainance of a higher concentration of SN-38. These results indicate that IHL-305 demonstrated superior antitumor activity against a wide range of tumors at lower doses than CPT-11.

Breast cancer resistance protein (BCRP/ABCG2) confers resistance to anticancer drugs such as 7-ethyl-10-hydroxycamptothecin (SN-38, an active metabolite of irinotecan), mitoxantrone, and topotecan. In this study, we examined the reversing effects of YHO-13177, a novel acrylonitrile derivative, and its water-soluble diethylaminoacetate prodrug YHO-13351 on the BCRP-mediated drug resistance. YHO-13177 potentiated the cytotoxicity of SN-38, mitoxantrone, and topotecan in both BCRP-transduced human colon cancer HCT116 (HCT116/BCRP) cells and SN-38–resistant human lung cancer A549 (A549/SN4) cells that express BCRP, but had little effect in the parental cells. In addition, YHO-13177 potentiated the cytotoxicity of SN-38 in human lung cancer NCI-H460 and NCI-H23, myeloma RPMI-8226, and pancreatic cancer AsPC-1 cells that intrinsically expressed BCRP. In contrast, it had no effect on P-glycoprotein–mediated paclitaxel resistance in MDR1-transduced human leukemia K562 cells and multidrug resistance-related protein 1–mediated doxorubicin resistance in MRP1-transfected human epidermoid cancer KB-3-1 cells. YHO-13177 increased the intracellular accumulation of Hoechst 33342, a substrate of BCRP, at 30 minutes and partially suppressed the expression of BCRP protein at more than 24 hours after its treatment in both HCT116/BCRP and A549/SN4 cells. In mice, YHO-13351 was rapidly converted into YHO-13177 after its oral or intravenous administration. Coadministration of irinotecan with YHO-13351 significantly increased the survival time of mice inoculated with BCRP-transduced murine leukemia P388 cells and suppressed the tumor growth in an HCT116/BCRP xenograft model, whereas irinotecan alone had little effect in these tumor models. These findings suggest that YHO-13351, a prodrug of YHO-13177, could be clinically useful for reversing BCRP-mediated drug resistance in cancer chemotherapy. Mol Cancer Ther; 10(7); 1252–63. ©2011 AACR.

A synergistic effect of P-glycoprotein (P-gp)/Abcb1a and breast cancer resistance protein (Bcrp)/Abcg2 was reported to limit the brain penetration of their common substrates. This study investigated this based on pharmacokinetics using Mdr1a/1b(-/-), Bcrp(-/-), and Mdr1a/1b(-/-)/Bcrp(-/-) mice. Comparison of the brain- and testis-to-plasma ratios (C(brain)/C(plasma) and C(testis)/C(plasma), respectively) of the reference compounds quinidine and dantrolene for P-gp and Bcrp, respectively, indicates that impairment of either P-gp and Bcrp did not cause any change in the efflux activities of Bcrp or P-gp, respectively, at both the blood-brain barrier (BBB) and blood-testis barrier (BTB). The C(brain)/C(plasma) and C(testis)/C(plasma) of the common substrates erlotinib, flavopiridol, and mitoxantrone were markedly increased in Mdr1a/1b(-/-)/Bcrp(-/-) mice even compared with Mdr1a/1b(-/-) and Bcrp(-/-) mice. Efflux activities by P-gp and Bcrp relative to passive diffusion at the BBB and BTB were separately evaluated based on the C(brain)/C(plasma) and C(testis)/C(plasma) in the knockout strains to the wild-type strain. P-gp made a larger contribution than Bcrp to the net efflux of the common substrates, but Bcrp activities were also significantly larger than passive diffusion. These parameters could reasonably account for the marked increase in C(brain)/C(plasma) and C(testis)/C(plasma) in the Mdr1a/1b(-/-)/Bcrp(-/-) mice. In conclusion, the synergistic effect of P-gp and Bcrp on C(brain)/C(plasma) and C(testis)/C(plasma) can be explained by their contribution to the net efflux at the BBB and BTB without any interaction between P-gp and Bcrp.

We reported that the co-polymer composed of vinylpyrrolidone and maleic acid selectively distributed into the kidneys after i.v. injection. To further optimize the renal drug delivery system, we assessed the renal targeting capability of anionized polyvinylpyrrolidone (PVP) derivatives after intravenous administration in mice. The elimination of anionized PVP derivatives from the blood decreased with increasing anionic groups, and the clearance of carboxylated PVP and sulfonated PVP from the blood was almost similar. But carboxylated PVP efficiently accumulated in the kidney, whereas sulfonated PVP was rapidly excreted in the urine. The renal levels of carboxylated PVP were about five-fold higher than sulfonated PVP. Additionally, carboxylated PVP was effectively taken up by the renal proximal tubular epithelial cells in vivo after i.v. injection. These anionized PVP derivatives did not show any cytotoxicity against renal tubular cells and endothelial cells in vitro. Thus, these carboxylated and sulfonated PVPs may be useful polymeric carriers for drug delivery to the kidney and bladder, respectively.

Background: Accumulating evidence reveals effectiveness of histone deacetylase (HDAC) inhibition in various types of cancer, and resminostat is a novel and oral HDAC inhibitor. In this study, we investigated the preclinical activity of resminostat in human non-small-cell lung cancer (NSCLC) cells, especially in combination with docetaxel (DTX). Materials and Methods: Anti-proliferative activity of resminostat was evaluated in 9 human NSCLC cell lines in vitro. Monolayers of cultured cells were exposed to resminostat and cell viability was determined. The amount of p21, acetylated histone H3 and α-tublin were analyzed by Western blotting in NCI-H460 cells exposed to resminostat. In addition, caspase-3 activity was measured. In a drug combination study, cells were simultaneously exposed to resminostat and DTX, and the synergistic effects of this drug combination were analyzed using the Combination Index, calculated by the median-effect method. For in vivo studies, a suspension of NCI-H460 cells was subcutaneously inoculated into the flank of male nude mice. The antitumor efficacies of oral resminostat alone or in combination with intravenous DTX were evaluated in this NSCLC xenograft model. Results: Resminostat exhibited antiproliferative activity in all tested cell lines. Sensitivity to resminostat was not influenced by the genetic status of KRAS among the cell lines (IC50 from 9 cell lines: 0.4-8.7 μmol/L). The treatment of cells with resminostat alone increased the levels of total p21 protein and acetylated histone H3. α-tublin was also acetylated by resminostat treatment and the level of acetylation was enhanced by the combination treatment with DTX. The amount of polymerized α-tubulin was increased by DTX treatment and this effect was greater in the combination treatment with resminostat than with DTX alone. Caspase-3 was more significantly activated by the combination treatment than with each mono-treatment. The Combination Index showed synergistic or additive effects in the resminostat plus DTX combination. The antitumor activities of resminostat were demonstrated in NCI-H460 tumor-bearing mice, where an up-regulation of p21 was accompanied by acetylation of histone H3 in the tumor tissues. The tumor growth inhibition ratio (IR) in the combination treatment was 2.6 and 1.8 times higher than with DTX alone or with resminostat alone, respectively, following a tolerable drug application schedule. Conclusion: These results demonstrated the potent activity of resminostat in NSCLC. The combination of resminostat and DTX appears to be a promising regimen to be tested in clinical trials in NSCLC patients. Based on this study, we initiated a phase I/II study in NSCLC patients to examine the safety and efficacy of this combination. Citation Format: Akimitsu Takagi, Hiroaki Konishi, Momomi Tsugane, Keisuke Taniguchi, Hiroyuki Takahashi, Yu Inutake, Akinobu Watanabe, Hiroshi Kodaira, Takeshi Matsuzaki. A novel and oral histone deacetylase inhibitor, resminostat, effectively suppresses the growth of non-small cell lung cancer in a xenograft mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5534. doi:10.1158/1538-7445.AM2014-5534

Background: Perifosine is an oral anticancer compound that inhibits the PH-domain of AKT, which is frequently activated in human cancers including gastric cancer. In this study, the mode of action of perifosine, especially in association with mTOR, and the antitumor activity in combination with paclitaxel were examined in human gastric cancer cell lines. Materials and Methods: The following human gastric cancer cell lines were used in this study: MKN1, MKN45, MKN74, AGS, and NCI-N87. Monolayers of cultured cells were exposed to perifosine for 48 hours and the antiproliferative activity was measured. The phosphorylated (p-)AKT status and its downstream molecules (e.g., PRAS40, TSC2, mTOR, 4E-BP1, and p70S6K) were analyzed using immunoblotting. In perifosine-treated cells, the induction of autophagy-like cell death was detected using LC3. With or without perifosine, the p-AKT (S473) levels were examined in rapamycin-treated cells. In a drug combination study, perifosine was used in combination with paclitaxel, and the synergistic effects of these drugs were quantified using the median-effect method to estimate the Combination Index. The antitumor efficacy of daily oral perifosine alone or in combination with intravenous paclitaxel was evaluated at various doses for 4 weeks in xenografted mice. The tumors at the time of necropsy were immunohistochemically examined for TUNEL, Ki-67 and AKT signal-related molecules. Results: Perifosine exhibited antiproliferative activity in the tested cell lines (GI50: 4.7-18.0 μmol/L), reducing p-AKT. The perifosine-induced inhibition of phosphorylation was also seen in molecules downstream of AKT, such as PRAS40, mTOR, and p70S6K. Perifosine also induced autophagy-like cell death, observed as the induction of type II LC3 along with cleaved PARP. The phosphorylation of AKT (S473) was induced by rapamycin treatment. While this phosphorylation was not induced by perifosine, the rapamycin-dependent phosphorylation of AKT was inhibited by perifosine. The Combination Index showed synergistic or additive effects when perifosine was used in combination with paclitaxel. The antitumor activities of perifosine were demonstrated in a dose-dependent manner in the 3 cell lines tested in mice. When perifosine was administered with paclitaxel to NCI-N87 cells in mice, the inhibitory ratio of the tumor increased to 78.8% from 61.7% for perifosine monotherapy and from 50.0% for paclitaxel monotherapy. The population of TUNEL-positive cells was higher in the combination therapy group than in the monotherapy group in the tumor tissues. This combination decreased the number of positive cells with Ki-67 and AKT signal molecules in the tissue. Conclusion: These results demonstrated that perifosine downregulates the mTOR function. The combination of perifosine and paclitaxel appears to be a promising regimen for the treatment of gastric cancer. Citation Format: Akimitsu Takagi, Momomi Tsugane, Hiroaki Konishi, Satoru Ishii, Ken-ichi Sata, Hiroshi Kodaira, Takeshi Matsuzaki. Perifosine, an AKT inhibitor, downregulates mTOR function and suppresses the growth of human gastric cancer cells in mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3994. doi:10.1158/1538-7445.AM2013-3994

Background: Irinotecan (CPT-11) is a prodrug of SN-38 that has antitumor activity in a wide range of solid tumors. IHL-305 is a PEGylated-liposomal formulation of CPT-11. The PK of liposomal agents is highly complex due to the variability in the disposition of the inactive-encapsulated drug and the release of active-drug from the liposome. We previously reported that age, body weight, and monocytes affect the PK and PD of PEGylated liposomal agents. Thus, we evaluated the effect of these factors on the PK and PD of IHL-305 as part of a phase I study. Methods: IHL-305 was administered IV over 1 h at 3.5, 7, 10.5, 14, 28, 33.5, 37, 50, 67, 80, 88, 120, 160, and 210 mg/m2 q 28 d. Serial plasma samples were obtained prior to infusion, at the end of infusion (EOI), and from 1 to 192 h after EOI. Plasma samples were processed to measure sum total (encapsulated + released) CPT-11, released CPT-11, SN-38 and SN-38 glucuronide (SN-38G). The total (lactone + hydroxy acid) forms were measured by HPLC. The area under the plasma concentration versus time curve (AUC) for each form was calculated from 0 to last sampling time and from 0 to ∞. The ratio of total body weight to ideal body weight (TBW/IBW) was calculated. Results: 39 patients (pts) (13 male) were treated. Median (range) of age and TBW/IBW were 60 years old (yo) (42–75 yo) and 1.16 (0.81–2.7), respectively. There was high inter-patient variability in the PK disposition of sum total CPT-11, released CPT-11, SN-38 and SN-38G. Sum total CPT-11 is associated with linear and non-linear clearance. The ratio of SN-38 to released CPT-11 and SN-38G to SN-38 were similar to those reported after irinotecan. Pts whose age and TBW/IBW were greater than the median of the study had a 1.7- to 2.6-fold higher ratio of released CPT-11 AUC to sum total CPT-11 AUC. In pts < 60 yo and in pts ≥ 60 yo, the ratio of % decrease in monocytes at nadir to % decrease in ANC at nadir were 1.65 ± 1.36 and 1.24 ± 0.68, respectively. There was an inverse relationship between pts age and % decrease in monocytes at nadir with younger pts having a higher % decrease in monocytes. Pts with a higher % decrease in monocytes at nadir have an increased clearance of sum total CPT-11 and increased exposure of released CPT-11 and ratio of released CPT-11 AUC to sum total CPT-11 AUC. Conclusions: PK and PD of IHL-305 are consistent with a PEGylated-liposomal carrier. IHL-305 has pharmacological advantages compared with irinotecan. The inter-patient variability in the PK and PD of IHL-305 was associated with age, body composition, and monocytes. Sponsored by Yakult Honsha Co., Ltd., Tokyo, Japan Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C127.