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SUMMARY The effect of human recombinant erythropoietin (Epo) on B cell responses was studied in a serum-free medium. Epo enhanced IgM production and thymidine uptake by a human IgM-producing lymphoblasloid cell line, CBL. This effect was specific to Epo since enhancement was blocked by anti-Epo antibody but not by control antibody. Among the various cytokines, interleukin-4 (IL-4) enhanced IgM production and thymidine uptake while IL-6 enhanced IgM production without affecting thymidine uptake. In contrast, other cytokines including IL-1β, IL-2, IL-5, interferon-alpha (IFN-α), interferon-gamma (IFN-γ), or granulocyte/macrophage colony-stimulating factor (GM-CSF) were without effect. However, the enhancing effect of Epo is different from that of IL-4 or IL-6, since Epo effect was not blocked by anti-IL-4 antibody or anti-IL-6 antibody. Moreover, specific binding of Epo was detected on CBL cells. Epo also enhanced immunoglobulin (IgG, IgM and IgA) production and thymidine uptake by purified tonsil small resting B cells stimulated by Staphylococcus aureus Cowan strain I (SAC) or by large activated B cells. In contrast, Epo had no effect on unstimulated smalt resting B cells. These results indicate that Epo could directly stimulate activated and differentiated B cells and could enhance B cell immunoglobulin production and proliferation.

Central nervous system (CNS) is one of the major cites for extramedullary relapse of Ph+ leukemias, which have been treated with imatinib mesylate (IM). The reason for this is that IM is a substrate for P-glycoprotein (P-gp) at the blood brain barrier and effluxed by it. We have already shown in the last annual meeting that INNO-406 had much stronger anti-tumor effects against the murine CNS leukemia model compared with IM, and INNO-406 is also effluxed from the murine CNS by P-gp. In this study, we investigated the combination effect of INNO-406 and P-gp inhibitors, verapamil or cyclosporin-A (CsA). First, we examined the growth-suppressive effect of INNO-406 and the combination with the P-gp inhibitors against the BCR-ABL positive leukemic cell line, K562 and the P-gp-overexpressing K562, K562/D1-9 cell line. K562/D1-9 showed 10 times higher resistant to both IM and INNO-406 compared with K562. Furthermore, both verapamil and CsA synergistically augmented the effect of INNO-406. Next, we investigated the pharmacokinetics of INNO-406 when orally administrated with CsA to mice. Mice were administrated p.o. with 50mg/kg of CsA 2 hours before INNO-406. We found that the concentration of INNO-406 in the CNS elevated by 2 times when combined with CsA, while the plasma concentration was decreased to two thirds of that when singly administrated with INNO-406. It was suggested that the decreased plasma concentration of INNO-406 seen here resulted from the increased uptake into the CNS by CsA inhibiting P-gp at the blood brain barrier. These changes of the drug distribution to the murine tissues may alter the anti-leukemic effect of INNO-406, thus we planned to investigate the combination effect of INNO-406 and CsA in the murine models of both CNS and systemic leukemia. We found that CsA significantly augmented the anti-tumor effect of INNO-406 in the CNS leukemia model. Moreover, in spite of the decreased plasma concentration of INNO-406, the combination with CsA also prolonged the survival phase of the mice in the systemic leukemia model, more significantly than single treatment of INNO-406 (Figure). This may be explained by which CsA increased the intracellular uptake of INNO-406, resulted from the direct inhibition of drug efflux via P-gp expressed in the leukemic cells. Phase I clinical study on INNO-406 is now underway in MD Anderson Cancer Center and in Frankfurt University. From the results of this study, we expected the effective application of INNO-406 in combination with P-gp inhibitor to the patients suffering from refractory Ph+ leukemia as well as CNS relapse. Download : Download high-res image (87KB) Download : Download full-size image Figure

Central nervous system (CNS) relapse accompanying prolonged administration of imatinib mesylate, an Abl-specific tyrosine kinase inhibitor, has recently become apparent as an impediment to the therapy of Philadelphia-chromosome-positive (Ph+) leukemia. CNS relapse may be explained by limited penetration of imatinib into the cerebrospinal fluid due to presence of P-glycoprotein (P-gp) at blood-brain barrier. To overcome imatinib-resistance mechanisms such as bcr-abl gene amplification, point mutations within ABL kinase domain, and activation of Lyn, we recently developed a specific dual BCR-ABL/Lyn inhibitor, INNO-406 (formerly NS-187), which is 25–55 times more potent than imatinib in vitro and at least 10 times more potent in vivo (Blood106: 3948–3954, 2005). The aim of this study was to investigate the efficacy of INNO-406 in treating CNS Ph+ leukemia. The intracellular accumulation of [14C]INNO-406 in P-gp overexpressing LLC-GA5-COL150 cells was much less than that in parental LLC-PK1 cells. The addition of 10 mM cyclosporin A (CsA) increased the intracellular accumulation of [14C]INNO-406 in both LLC-PK1 cells and LLC-GA5-COL150 cells. The peak concentration of INNO-406 in the brain when 30 mg/kg INNO-406 was administered p.o. was 50 ng/ g (87 nM), representing only 10% of plasma drug level. These findings suggested that INNO-406 is also a substrate of P-gp, as is imatinib. However, the residual concentration of INNO-406 in the CNS was enough to inhibit the growth of Ph+ leukemic cells according to the in vitro data. To increase the concentration of INNO-406 in CNS, we next examined the combined effects of CsA. In the brain, the concentration of INNO-406 was doubled following prior administration of 50 mg/kg CsA. Since pharmacokinetic studies suggested the possible effects of INNO-406 against CNS Ph+ leukemia, we investigated in vivo anti-CNS Ph+ leukemia effects of INNO-406 alone and combination of INNO-406 and CsA using immunodeficient mice (nude or NOD/SCID) which received Ph+ leukemic cells into the cerebral ventricle. INNO-406 alone inhibited growth of leukemic cells harboring either wild type or mutated BCR-ABL such as E255K and M351T in CNS. Furthermore, CsA significantly enhanced anti-CNS Ph+ leukemia effects of INNO-406 in vivo not only against cells harboring wild type BCR-ABL but also against cells harboring BCR-ABL/M351T (Figure). In conclusion, INNO-406 was found to inhibit Ph+ leukemic cell growth in CNS in spite of efflux of the compound by P-gp, and CsA augmented the anti-CNS Ph+ leukemia effects of INNO-406. Phase I clinical study on INNO-406 was initiated in the U.S.A. in July 2006. The efficacy and safety of INNO-406 in the treatment of leukemias is expected to be verified by early-phase clinical trials. Figure Figure

A complementary DNA (cDNA) encoding a novel member of organic anion transoporter, OAT-K1, expressed specifically in the kidney of rats was isolated, and the transport characteristics were assessed by LLC-PK, cells stably expressing OAT-K1 (LLC-OAT-K1). The OAT-K1 cDNA (2, 788 bp) consists of a 669-amino acid protein (calculated molecular mass of 74 kDa) which shows 72% identy with the rat liver Na+-independent organic anion transporting polypeptide (oatp). Northern blot analysis and reverse transcription-coupled PCR revealed that the rat OAT-K1 mRNA is expressed predominantly in the kidney medulla, but not in the liver. LLC-OAT-K1 monolayers showed that the OAT-KI mediates basolateral uptake of methotrexate, but not taurocholate, p-aminohippurate, prostaglandin E2, and leukotriene C4. Folate, sulfobromophthalein and DIDS inhibited the methotrexate accumulation markedly. Furthermore, some steroides and nonsteroidal anti-inflammatory drugs showed the potent inhibitory effects on methotrexate uptake by LLC-OAT-K1 monolayers. These findings suggest that the rat OAT-K1 is a new organic anion transporter involved in detoxification process in the kidney, mediating basolateral uptake of anionic xenobiotics.

We found a system of Na+-dependent uptake of fructose by rat renal brush-border membrane vesicles. It consisted of two saturable components, and was thought to involve at least two transporters. rNaGLT1, a novel glucose transporter in rat kidney, showed fructose uptake as well as α-methyl-D-glucopyranoside uptake by transfected HEK293 cells. The features of the lower affinity type of fructose transporter in the brush-border membranes, such as affinity and substrate recognition, were very comparable with those of rNaGLT1-transfected HEK293 cells. These results indicated that rNaGLT1 is a primary fructose transporter in rat renal brush-border membranes.

Cellular and molecular aspects of drug transport in the kidney. The kidney plays an important role in the elimination of numerous hydrophilic xenobiotics, including drugs, toxins, and endogenous compounds. It has developed high-capacity transport systems to prevent urinary loss of filtered nutrients, as well as electrolytes, and simultaneously to facilitate tubular secretion of a wide range of organic ions. Transport systems for organic anions and cations are primarily involved in the secretion of drugs in renal tubules. The identification and characterization of organic anion and cation transporters have been progressing at the molecular level. To date, many members of the organic anion transporter (OAT), organic cation transporter (OCT), and organic anion-transporting polypeptide (oatp) gene families have been found to mediate the transport of diverse organic anions and cations. It has also been suggested that ATP-dependent primary active transporters such as MDR1/P-glycoprotein and the multidrug resistance-associated protein (MRP) gene family function as efflux pumps of renal tubular cells for more hydrophobic molecules and anionic conjugates. Tubular reabsorption of peptide-like drugs such as β-lactam antibiotics across the brush-border membranes appears to be mediated by two distinct H+/peptide cotransporters: PEPT1 and PEPT2. Renal disposition of drugs is the consequence of interaction and/or transport via these diverse secretory and absorptive transporters in renal tubules. Studies of the functional characteristics, such as substrate specificity and transport mechanisms, and of the localization of cloned drug transporters could provide information regarding the cellular network involved in renal handling of drugs. Detailed information concerning molecular and cellular aspects of drug transporters expressed in the kidney has facilitated studies of the mechanisms underlying renal disposition as well as transporter-mediated drug interactions.

Organic cation transporters play an important role in the secretion of cationic drugs as well as endogenous cationic metabolites in the renal tubules. Immunoblotting showed the presence of organic cation transporter proteins, rOCT1 and rOCT2, in the rat kidney. By immunofluorescence microscopy, rOCT1 was shown to be concentrated in the proximal tubules in the renal cortex. rOCT2, on the other hand, was rich in the proximal tubules in the outer stripe of the outer medulla. Confocal microscopy revealed that both rOCT1 and rOCT2 were localized to the basolateral membranes of these tubule cells. These findings directly show that rOCT1 and rOCT2 are basolateral membrane proteins and are differentially distributed along the proximal tubules.

The renal proximal tubular cells play a principal role in limiting or preventing toxicity by actively secreting organic anions from the circulation into the urine. We isolated a cDNA coding a novel rat kidney specific organic anion transporter, OAT-K1, mediating transport of methotrexate (MTX). Moreover, we have isolated a new cDNA coding a rat OAT-K2, showing the 91% amino acid identity with OAT-K1. In this study, the mRNA distribution along the nephron segments and the transport characteristics of OAT-K1 and OAT-K2 have been analyzed. By the use of a reverse transcription-coupled PCR, OAT-K1 and OAT-K2 mRNAs were detected predominantly in the proximal straight tubules. When expressed in Xenopus oocytes, OAT-K1 mediated the uptake of MTX and folate, but not of taurocholate (TCA) and prostaglandin E2 (PGE2), although OAT-K2 stimulated the uptake of MTX, folate, TCA and PGE2. In stable transfectants (MDCK OAT-K1 and MDCK-OAT-K2), each transporter was localized functionally to the apical membrane and showed transport activity similar to those in the oocytes. The efflux of preloaded MTX was enhanced in both MDCK-OAT-K1 and MDCK-OAT-K2 cells. These results suggest that both OAT-K1 and OAT-K2 are apical membrane bidirectional organic anion transporters, and participate in epithelial transport of lipophilic organic anions in the kidney.

Monitoring of pharmacodynamics in addition to pharmacokinetics is one of strategies to individualize mycophenolate mofetil therapy. The purpose of this study was to develop sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for evaluation of the pharmacokinetics and pharmacodynamics of mycophenolic acid (MPA). Concentrations of mycophenolic acid glucuronide (MPAG), mycophenolic acid acyl-glucuronide, as well as unbound MPA and MPAG, were determined, and inosine-5'-monophosphate dehydrogenase activity was calculated by measuring concentrations of produced xanthosine-5'-monophosphate (XMP) and intracellular adenosine-5'-monophosphate after incubation of peripheral blood mononuclear cell (PBMC) lysates. A metal-free Mastro(TM) column and two gradient patterns were used to improve the quantification limit of XMP to 0.1 μM. In the clinical MPA concentration range, the linearity of the calibration curve, inter- and intra-day precision and accuracy satisfied the relevant US Food and Drug Administration guidelines. The MPA concentrations in hematopoietic stem cell transplant (HSCT) patients determined by the enzyme assay and the present LC-MS/MS method showed a good correlation (r(2) = 0.95, p < 0.001). In this study, we report sensitive and validated LC-MS/MS methods to evaluate the pharmacokinetics and pharmacodynamics of MPA, which are sufficiently sensitive to assess small quantities of PBMC lysates collected shortly after HSCT., Article first published online: 26 JAN 2015

Role of kidney-specific organic anion transporters in the urinary excretion of methotrexate. Background High-dose folinic acid is used to accelerate methotrexate elimination to avoid renal toxicity of the drug. The present study was carried out to examine the role of the renal organic anion transporters OAT-K1 and OAT-K2 in the urinary excretion of methotrexate, especially in the methotrexate-folinic acid rescue therapy. Methods Madin-Darby canine kidney cells stably expressing OAT-K1 and OAT-K2 were used for the in vitro transport study; 5/6 nephrectomized rats were used to detect changes in mRNA expression levels of OAT-K1 and OAT-K2 and to evaluate methotrexate pharmacokinetics under conditions of renal insufficiency. Results Methotrexate efflux mediated by these transporters in stable transfectants was stimulated in the presence of extracellular folic acid and folinic acid, suggesting that they could serve as anion exchangers to enhance the apical efflux of methotrexate. The mRNA expression levels of OAT-K1 and OAT-K2 were markedly diminished after 5/6 nephrectomy, but those of multidrug resistance associated protein 2, which could transport methotrexate, were maintained. Renal clearance of methotrexate was markedly decreased in 5/6 nephrectomized rats compared with that in sham-operated rats. Additional folinic acid treatment resulted in a significant increase in methotrexate renal clearance in sham-operated rats but not in 5/6 nephrectomized rats. Conclusions The decreased expressions of OAT-K1 and OAT-K2 may be attributable to the longer exposure to methotrexate and ineffective folinic acid rescue. In terms of contributing to patient safety, renal clearance of methotrexate, especially folinic acid-stimulated tubular secretion of the drug via these transporters, would be a key factor in methotrexate therapy.

The patient is a 3-year-old boy who received living-donor liver transplantation (LDLT) for hepatoblastoma, with his mother as the donor. Oral tacrolimus was started at a dose of 0.3 mg every 12 h from day 1, with the dosage adjusted on the basis of trough concentrations. The levels of aspartate aminotransferase (AST), alanine transferase (ALT), and total bilirubin (T-bil) were 110 U/L, 182 U/L, and 12.6 mg/dL, respectively, when chronic rejection (CR) was pathologically diagnosed. Then, sirolimus at a dose of 1.0 mg/d was added to the tacrolimus-based regimen. The T-bil level rapidly decreased to 5.4 mg/dL, without changes in AST and ALT. Because the intracellular receptor of sirolimus and tacrolimus is FK506-binding protein 12, we switched tacrolimus to cyclosporine at a dose of 60 mg/d to avoid competitive inhibition between these 2 drugs. The target trough concentration of sirolimus and cyclosporine was set to around 15 ng/mL and 180 ng/mL, respectively. The concentration/dose ratio of sirolimus was significantly correlated with the blood cyclosporine level (r=0.5293, p

Renal organic anion transporter OAT-K1 was stably transfected in MDCK cells and examined for its transport characteristics and membrane localization. OAT-K1 mediated both uptake and efflux of methotrexate in the apical membranes. Immunoblotting showed that the apparent molecular mass of the expressed OAT-K1 was 50 kDa, which was comparable to that found in the rat renal brush-border membranes. The OAT-K1-mediated methotrexate transport was significantly inhibited in the presence of several organic anions such as folate and sulfobromophthalein. These findings suggest that OAT-K1 mediates bidirectional methotrexate transport across the apical membranes, and may be involved in the renal handling of methotrexate.

The potential influence of the multidrug resistance 1 (MDR1) gene and the cytochrome P450 (CYP) genes, CYP3A4 and CYP3A5, on the oral clearance (CL/F) of tacrolimus in adult living-donor liver transplant patients was examined. Furthermore, the development of renal dysfunction was analyzed in relation to the CYP3A5 genotype.Sixty de novo adult liver transplant patients receiving tacrolimus were enrolled in this study. The effects of various covariates (including intestinal and hepatic mRNA levels of MDR1 and CYP3A4, measured in each tissue taken at the time of transplantation, and the CYP3A5*3 polymorphism) on CL/F during the first 50 days after surgery were investigated with the nonlinear mixed-effects modeling program.CL/F increased linearly until postoperative day 14, and thereafter reached a steady state. The initial CL/F immediately after liver transplantation was significantly affected by the intestinal MDR1 mRNA level (P0.005). Furthermore, patients carrying the CYP3A5*1 allele in the native intestine, but not in the graft liver, showed a 1.47 times higher (95% confidence interval, 1.17-1.77 times, P0.005) recovery of CL/F with time than patients having the intestinal CYP3A5*3/*3 genotype. The cumulative incidence of renal dysfunction within 1 year after transplantation, evaluated by the Kaplan-Meier method, was significantly associated with the recipient's but not donor's CYP3A5 genotype (*1/*1 and *1/*3 vs. *3/*3: recipient, 17 vs. 46%, P0.05; donor, 35 vs. 38%, P=0.81).These findings suggest that the CYP3A5*1 genotype as well as the MDR1 mRNA level in enterocytes contributes to interindividual variation in the CL/F of tacrolimus in adult recipients early after living-donor liver transplantation. Furthermore, CYP3A5 in the kidney may play a protective role in the development of tacrolimus-related nephrotoxicity.

Pemetrexed plus carboplatin therapy is widely administered to patients with non-squamous non-small cell lung cancer. Although severe neutropenia is often observed during this combination therapy, its predictive factors are unknown. Therefore, we investigated the predictive factors for severe neutropenia in 77 patients treated with this combination therapy at the Department of Respiratory Medicine, Kyushu University Hospital, between September 2009 and September 2013. All data were retrospectively collected from the electronic medical record system, and univariate and multivariate logistic regression analyses were performed to identify risk factors for grade 3 or 4 neutropenia. Among the 77 patients, 34 (44%) developed grade 3 or 4 neutropenia. Multivariate analysis revealed that lower baseline hemoglobin values (odds ratio [OR], 1.97 per 1 g/dL decrease; 95% confidence interval [CI], 1.39-2.99, p

Telaprevir (TVR) is a protease inhibitor used in combination with pegylated interferon alfa-2b and ribavirin for hepatitis C, and TVR strongly inhibits CYP3A4 and CYP3A5. We reported successful TVR treatment of liver transplant patients with recurrence of hepatitis C during receiving immunosuppressive therapy. Before initiation of triple therapy, all patients switched from tacrolimus to cyclosporine, which has a lower inhibitory effect on CYP3A4 and CYP3A5 than tacrolimus. To avoid graft failure, we measured the cyclosporine blood concentrations at 0, 2, and 6 h after administration to maintain the target level (150-200 ng/mL) within 1 week after initiation of TVR and adjusted the dose of cyclosporine. The dose of cyclosporine was decreased 0.24-0.40 fold in all patients after initiation of TVR treatment. In 3 patients, the dose of TVR was decreased two-thirds of starting dose because of adverse effects, including anorexia and skin rash. However, the HCV RNA level rapidly decreased to undetectable levels within 1 month. Furthermore, all patients completed the TVR therapy in 12 weeks and did not experience liver graft rejection. In addition, we found the rapid elimination of inhibitory effect of TVR on the disposition of cyclospirne in the all four cases and therefore, rapid increase in the dosage of cyclosporine would be required immediately after the end of TVR administration. These results suggest that frequent measurement of cyclosporine levels was important for successful TVR triple therapy and prevention of rejection.

The bioavailability of structurally unrelated drugs is limited by active secretion via the multidrug resistance gene (MDR1) product P-glycoprotein (Pgp) from enterocyte into lumen as well as intestinal metabolism by cytochrome P450 IIIA4 (CYP3A4). In the present study, we analyzed whether genetic polymorphism of the MDR1 had some influence on the intestinal expression levels of Pgp and CYP3A4 and the tacrolimus concentration/dose ratio over the first postoperative days in recipients of living-donor liver transplantation (LDLT). Genotyping assays were performed for the major 10 polymorphisms in the MDR1 gene by the polymerase chain reaction-restriction enzyme length polymorphism method. The allele frequencies of variations at five positions were almost comparable with those in the former studies in Caucasians and Japanese, but there was no variation at the other five positions. Although no polymorphism correlated with the intestinal expression of MDR1 mRNA or the tacrolimus concentration/dose ratio in the LDLT recipients, the C3435T polymorphism significantly affected the intestinal expression level of CYP3A4 mRNA as follows; 3435C/C>3435C/T (P 3435T/T (P < 0.01 vs. 3435C/C). Therefore, the identified polymorphisms including C3435T in the MDR1 gene were indicated to have no influence on the intestinal expression level of Pgp or the tacrolimus concentration/dose ratio in the recipients of LDLT. On the other hand, the C3435T polymorphism of MDR1 was suggested to correlate with the enterocyte expression of CYP3A4 rather than Pgp linking unknown genetic variation in CYP3A4 gene.

For hormone refractory prostate carcinoma, a combination therapy of paclitaxel and carboplatin is used to expect life extension. We investigated the pharmacokinetics of carboplatin in Japanese prostate cancer patients (n=10, 55-72 years), and evaluated the usefulness of Calvert's formula in the individualized dosing adjustment. They were intravenously administered carboplatin (area under the free plasma concentration versus time curve (AUC)=5 mg.min/ml), following the intravenous administration of paclitaxel (175 mg/m(2)). The dosage of carboplatin for each patient was determined with Calvert's formula using individual creatinine clearance values. Plasma concentration of total platinum was measured sequentially and the pharmacokinetic parameters of carboplatin were determined in each patient. Plasma concentration of total carboplatin after intravenous infusion well fitted the two-compartment model. Carboplatin clearance was 62.0+/-12.7 ml/min (mean+/-S.D.), and linearly related to the individual creatinine clearance (r(2)=0.64, p

It has been reported that hepatic and intestinal cytochrome P450 (CYP) 3A4, CYP3A5 and P-glycoprotein affect the pharmacokinetics of tacrolimus, and that these proteins are associated with the large inter-individual variation in the pharmacokinetics of this drug. We previously showed that the concentration/dose ratio of tacrolimus tended to be lower in recipients of living-donor liver transplantation (LDLT) with a CYP3A5*1/*1-carrying graft. However, the effect of intestinal CYP3A5 remains to be elucidated. In the present study, we examined the CYP3A5 genotype in both recipients and donors, and the effect of the recipients' polymorphism on the concentration/dose ratio of tacrolimus in patients after LDLT. The CYP3A5*3 allele frequency was 80% in recipients and 77% in donors. The intestinal CYP3A5 mRNA expression level was significantly associated with genotype. The tacrolimus concentration/dose ratio was lower in recipients with the CYP3A5*1/*1 and *1/*3 genotype (CYP3A5 expressors) compared to the CYP3A5*3/*3 genotype (non-expressors). Amongst the combination of CYP3A5 genotypes between the graft liver and the native intestine, CYP3A5 expressors in both the graft liver and the native intestine had the lowest concentration/dose ratio of tacrolimus during 35 days after LDLT. Patients with the intestinal CYP3A5*1 genotype tended to require a higher dose of tacrolimus compared to the other group with the same hepatic CYP3A5 genotype. These results indicate that intestinal CYP3A5, as well as hepatic CYP3A5, plays an important role in the first-pass effect of orally administered tacrolimus.