The Use of an Antioxidant Enables Accurate Evaluation of the Interaction of Curcumin on Organic Anion-Transporting Polypeptides 4C1 by Preventing Auto-Oxidation.

Flavonoids have garnered attention because of their beneficial bioactivities. However, some flavonoids reportedly interact with drugs via transporters and may induce adverse drug reactions. This study investigated the effects of food ingredients on organic anion-transporting polypeptide (OATP) 4C1, which handles uremic toxins and some drugs, to understand the safety profile of food ingredients in renal drug excretion. Twenty-eight food ingredients, including flavonoids, were screened. We used ascorbic acid (AA) to prevent curcumin oxidative degradation in our method. Twelve compounds, including apigenin, daidzein, fisetin, genistein, isorhamnetin, kaempferol, luteolin, morin, quercetin, curcumin, resveratrol, and ellagic acid, altered OATP4C1-mediated transport. Kaempferol and curcumin strongly inhibited OATP4C1, and the Ki values of kaempferol (AA(-)), curcumin (AA(-)), and curcumin (AA(+)) were 25.1, 52.2, and 23.5 µM, respectively. The kinetic analysis revealed that these compounds affected OATP4C1 transport in a competitive manner. Antioxidant supplementation was determined to benefit transporter interaction studies investigating the effects of curcumin because the concentration-dependent curve evidently shifted in the presence of AA. In this study, we elucidated the food-drug interaction via OATP4C1 and indicated the utility of antioxidant usage. Our findings will provide essential information regarding food-drug interactions for both clinical practice and the commercial development of supplements.

Cost-Effectiveness Analysis of Cyclin-Dependent Kinase 4/6 Inhibitor Palbociclib for Inoperable or Recurrent Breast Cancer.

BACKGROUND: Palbociclib and endocrine therapy has been approved to treat hormone receptor-positive/human epidermal growth factor receptor 2-negative inoperable or recurrent breast cancer in Japan. However, this cotherapy imposes an economic burden on both patients and society because of its high cost. In this study, we assessed the cost-effectiveness of cotherapy with palbociclib and fulvestrant compared to fulvestrant monotherapy for inoperable or recurrent breast cancer. METHODS: The three-state Markov model was built by taking into count health stats in inoperable or recurrent breast cancer. The clinical outcomes of the therapies were drawn from published randomized controlled trials. Total regimen cost was calculated from medical receipts of patients at the Yamagata University Hospital. The cost-effectiveness was evaluated by the incremental cost-effectiveness ratio(ICER), in case that it was below 400,000 Yen per month. Markov chain Monte Carlo simulation was performed to assess probability. RESULTS: Acquisition cost of palbociclib and fulvestrant and fulvestrant monotherapy was 6,209,554 JPY and 780,870 JPY, and 25.7 and 22.8 months were achieved, respectively. ICER for the cotherapy was 1,847,721 JPY/quality adjusted life month(QALM)gained. CONCLUSIONS: The palbociclib and fulvestrant therapy provided better health outcomes than conventional fulvestrant monotherapy, but were costly and suggested to be less cost-effective.

Glutathione depletion results in S-nitrosylation of protein disulfide isomerase in neuroblastoma cells.

AIMS: Protein disulfide isomerase (PDI) is an essential enzyme involved in oxidative protein folding. PDI is S-nitrosylated in the brains of Alzheimer's disease patients, and S-nitrosylated PDI is considered one of main causes of Alzheimer's disease. However, the mechanisms underlying PDI S-nitrosylation have not yet been elucidated. Because glutathione (GSH) depletion is a pathological feature of Alzheimer's disease, we investigated the effect of GSH depletion on the S-nitrosylation level of PDI. MAIN METHODS: SH-SY5Y cells, which is a human derived neuroblastoma cells, were used in this study. Glutamate and buthionine sulfoximine (BSO) were used as GSH depletors. S-nitrosylated PDI was detected by biotin-switch assay. KEY FINDINGS: GSH depletion by glutamate, a cystine/glutamate antiporter xCT inhibitor, increased S-nitrosylated PDI at C343 in SH-SY5Y cells, and induced IRE1α phosphorylation. BSO, a γ-glutamylcysteine synthetase inhibitor, also increased S-nitrosylated PDI and phosphorylated IRE1α upon GSH depletion. Because S-nitrosylated PDI at C343 is stable in neuro cells, S-nitrosylated PDI by GSH depletion progresses to neurodegeneration by the induction of endoplasmic reticulum stress via phosphorylated IRE1α signaling from the early to late stage. Furthermore, treatment with neohesperidin, but not N-acetylcysteine (NAC), improved PDI S-nitrosylation level in GSH-depleted SH-SY5Y cells because nitrosylated compound of NAC induces PDI S-nitrosylation. SIGNIFICANCE: The results of our study provide a new insight into the mechanisms of neurodegeneration, and may be useful for the development of drugs for Alzheimer's diseases.

A hydrolysate of poly-trans-[(2-carboxyethyl)germasesquioxane] (Ge-132) suppresses Cav3.2-dependent pain by sequestering exogenous and endogenous sulfide.

Poly-trans-[(2-carboxyethyl)germasesquioxane] (Ge-132), an organogermanium, is hydrolyzed to 3-(trihydroxygermyl)propanoic acid (THGP) in aqueous solutions, and reduces inflammation, pain and cancer, whereas the underlying mechanisms remain unknown. Sulfides including H2S, a gasotransmitter, generated from l-cysteine by some enzymes including cystathionine-γ-lyase (CSE), are pro-nociceptive, since they enhance Cav3.2 T-type Ca2+ channel activity expressed in the primary afferents, most probably by canceling the channel inhibition by Zn2+ linked via coordinate bonding to His191 of Cav3.2. Given that germanium is reactive to sulfur, we tested whether THGP would directly trap sulfide, and inhibit sulfide-induced enhancement of Cav3.2 activity and sulfide-dependent pain in mice. Using mass spectrometry and 1H NMR techniques, we demonstrated that THGP directly reacted with sulfides including Na2S and NaSH, and formed a sulfur-containing reaction product, which decreased in the presence of ZnCl2. In Cav3.2-transfected HEK293 cells, THGP inhibited the sulfide-induced enhancement of T-type Ca2+ channel-dependent membrane currents. In mice, THGP, administered systemically or locally, inhibited the mechanical allodynia caused by intraplantar Na2S. In the mice with cyclophosphamide-induced cystitis and cerulein-induced pancreatitis, which exhibited upregulation of CSE in the bladder and pancreas, respectively, systemic administration of THGP as well as a selective T-type Ca2+ channel inhibitor suppressed the cystitis-related and pancreatitis-related visceral pain. These data suggest that THGP traps sulfide and inhibits sulfide-induced enhancement of Cav3.2 activity, leading to suppression of Cav3.2-dependent pain caused by sulfide applied exogenously and generated endogenously.

Bile Acid-Drug Interaction via Organic Anion-Transporting Polypeptide 4C1 Is a Potential Mechanism of Altered Pharmacokinetics of Renally Excreted Drugs.

Patients with liver diseases not only experience the adverse effects of liver-metabolized drugs, but also the unexpected adverse effects of renally excreted drugs. Bile acids alter the expression of renal drug transporters, however, the direct effects of bile acids on drug transport remain unknown. Renal drug transporter organic anion-transporting polypeptide 4C1 (OATP4C1) was reported to be inhibited by chenodeoxycholic acid. Therefore, we predicted that the inhibition of OATP4C1-mediated transport by bile acids might be a potential mechanism for the altered pharmacokinetics of renally excreted drugs. We screened 45 types of bile acids and calculated the IC50, Ki values, and bile acid−drug interaction (BDI) indices of bile acids whose inhibitory effect on OATP4C1 was >50%. From the screening results, lithocholic acid (LCA), glycine-conjugated lithocholic acid (GLCA), and taurine-conjugated lithocholic acid (TLCA) were newly identified as inhibitors of OATP4C1. Since the BDI index of LCA was 0.278, LCA is likely to inhibit OATP4C1-mediated transport in clinical settings. Our findings suggest that dose adjustment of renally excreted drugs may be required in patients with renal failure as well as in patients with hepatic failure. We believe that our findings provide essential information for drug development and safe drug treatment in clinics.

Clinical Importance of Plasma Drug Concentration of Oral Molecular Targeted Drugs for Renal Cell Carcinoma.

PURPOSE: Therapeutic drug monitoring (TDM) is widely used in clinical practice to maximize drug efficacy and minimize toxicities. Currently, it is also practiced in the use of oral molecular targeted drugs. The objective of this study was to assess the clinical importance of measuring the systemic concentration of oral molecular targeted drugs used to treat renal cell carcinoma (RCC). METHODS: The systemic concentrations of the oral molecular targeted drugs sorafenib, sunitinib, axitinib, pazopanib, and everolimus used for RCC were useful for therapeutic interventions, and clinical outcomes were evaluated retrospectively. RESULTS: The interventional use of systemic drug concentration was confirmed in 26 of 87, and their categories are presented. The systemic concentration of sunitinib was useful in dose reduction and/or discontinuation (n = 10), dose escalation (n = 3), and adherence monitoring (n = 2). Nine of the 10 patients whose dose was reduced showed reduced adverse event. Two patients who were intervened in adherence monitor showed improved adherence. For axitinib, dose reduction and/or discontinuation (n = 1) and dose escalation (n = 6) were confirmed. For pazopanib, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, both of them were confirmed to have reduced adverse events. For everolimus, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, a patient with reduced dose recovered from adverse events. Interventions for sorafenib were not identified. CONCLUSIONS: This study demonstrated that systemic concentrations of oral molecular targeted drugs for RCC were considered to be clinically useful for dose adjustment, monitoring of treatment adherence, and the detection of drug interactions. Moreover, this information could be successfully used to guide individualized therapy to maximize the antitumor effects of these drugs.

Glucose-induced oxidative stress leads to in S-nitrosylation of protein disulfide isomerase in neuroblastoma cells.

BACKGROUND: Dementia places a significant burden on both patients and caregivers. Since diabetes is a risk factor for dementia, it is imperative to identify the relationship between diabetes and cognitive disorders. Protein disulfide isomerase (PDI) is an enzyme for oxidative protein folding. PDI S-nitrosylation is observed in the brain tissues of Alzheimer's disease patients. The aim of this study is to clarify the relationship between PDI S-nitrosylation and diabetes. METHODS: We used SH-SY5Y cells cultured in high-glucose media. RESULTS: S-nitrosylated PDI level increased at 7 days and remained high till 28 days in SH-SY5Y cells cultured in high-glucose media. Using PDI wild-type- or PDI C343S-expressing SH-SY5Y cells, PDI C343 was identified as the site of glucose-induced S-nitrosylation. IRE1α and PERK were phosphorylated at day 14 in the SH-SY5Y cells cultured in high-glucose media, and the phosphorylated status was maintained to day 28. To determine the effect of S-nitrosylated PDI on endoplasmic reticulum stress signaling, SH-SY5Y cells were treated with S-nitrosocystein (SNOC) for 30 min, following which the medium was replaced with SNOC-free media and the cells were cultured for 24 h. Only phosphorylated IRE1α treated with SNOC was associated with PDI S-nitrosylation. Neohesperidin, a flavonoid in citrus fruits, is a natural antioxidant. The treatment with neohesperidin in the final 7 days of glucose loading reversed PDI S-nitrosylation and improved cell proliferation. CONCLUSION: Glucose loading leads to S-nitrosylation of PDI C343 and induces neurodegeneration via IRE1α phosphorylation. GENERAL SIGNIFICANCE: The results may be useful for designing curative treatment strategies for dementia.

Role of OATP4C1 in Renal Handling of Remdesivir and its Nucleoside Analog GS-441524: The First Approved Drug for Patients with COVID-19.

PURPOSE: Remdesivir and its active metabolite are predominantly eliminated via renal route; however, information regarding renal uptake transporters is limited. In the present study, the interaction of remdesivir and its nucleoside analog GS-441524 with OATP4C1 was evaluated to provide the detailed information about its renal handling. METHODS: We used HK-2 cells, a proximal tubular cell line derived from normal kidney, to confirm the transport of remdesivir and GS-441524. To assess the involvement of OATP4C1 in handling remdesivir and GS-441524, the uptake study of remdesivir and GS-441524 was performed by using OATP4C1-overexpressing Madin-Darby canine kidney II (MDCKII) cells. Moreover, we also evaluated the IC50 and Ki value of remdesivir. RESULTS: The time-dependent remdesivir uptake in HK-2 cells was observed. The results of inhibition study using OATs and OCT2 inhibitors and OATP4C1 knockdown suggested the involvement of renal drug transporter OATP4C1. Remdesivir was taken up by OATP4C1/MDCKII cells. OATP4C1-mediated uptake of remdesivir increased linearly up to 10 min and reached a steady state at 30 min. Remdesivir inhibited OATP4C1-mediated transport in a concentration-dependent manner with the IC50 and apparent Ki values of 42 ± 7.8 µM and 37 ± 6.9 µM, respectively. CONCLUSIONS: We have provided novel information about renal handling of remdesivir. Furthermore, we evaluated the potential drug interaction via OATP4C1 by calculating the Ki value of remdesivir. OATP4C1 may play a pivotal role in remdesivir therapy for COVID-19, particularly in patients with kidney injury.

Phase II study of trifluridine/tipiracil (TAS-102) therapy in elderly patients with colorectal cancer (T-CORE1401): geriatric assessment tools and plasma drug concentrations as possible predictive biomarkers.

PURPOSE: The current study aimed to determine the efficacy of trifluridine/tipiracil for elderly patients with advanced colorectal cancer. METHODS: This single-arm, open-label, multicenter, phase II study included elderly patients aged 65 years or more who had fluoropyrimidine-refractory advanced colorectal cancer and received trifluridine/tipiracil (70 mg/m2, days 1-5 and 8-12, every 4 weeks). The primary endpoint was progression-free survival (PFS), while secondary endpoints included overall survival (OS), overall response rate (ORR), toxicities, association between efficacy and geriatric assessment scores, and association between toxicity and plasma drug concentrations. RESULTS: A total of 30 patients with a mean age of 73 years were enrolled. Median PFS was 2.3 months (95% confidence interval, 1.9-4.3 months), while median OS was 5.7 months (95% confidence interval, 3.7-8.9 months). Patients had an ORR of 0%, with 57% having stable disease. Grade 4 neutropenia was observed in 13% of the patients. Patients with a higher G8 score (15 or more) showed longer PFS than those with a lower G8 score (median 4.6 vs. 2.0 months; p = 0.047). Moreover, patients with grade 3 or 4 neutropenia showed higher maximum trifluridine concentrations than those with grade 1 or 2 neutropenia (mean 2945 vs. 2107 ng/mL; p = 0.036). DISCUSSION: The current phase II trial demonstrated that trifluridine/tipiracil was an effective and well-tolerated option for elderly patients with advanced colorectal cancer. Moreover, geriatric assessment tools and/or plasma drug concentration monitoring might be helpful in predicting the efficacy and toxicities in elderly patients receiving this drug. TRIAL REGISTRATION NUMBER: UMIN000017589, 15/May/2015 (The University Hospital Medical Information Network).

ATP-Binding Cassette Transporter C4 is a Prostaglandin D2 Exporter in HMC-1 cells.

ATP-binding cassette transporter C4 (ABCC4) is associated with multidrug resistance and the regulation of cell signalling. Some prostaglandins (PGs), including: PGE2, PGF2α, PGE3, and PGF3α are known substrates of ABCC4, and are released from some types of cells to exert their biological effects. In the present study, we demonstrate that PGD2 is a novel substrate of ABCC4 using a transport assay based on inside-out membrane vesicles prepared from ABCC4-overexpressing cells. Then, we used two types of cell lines with confirmed ABCC4 mRNA and PGD2 release capacity (human mast cell lines HMC-1 cells and human rhabdomyosarcoma cell lines TE671 cells) to evaluate the contribution of ABCC4. The extracellular levels of PGD2 were unchanged following addition of a selective ABCC4 inhibitor in TE671 cells. Pharmacological inhibition and knockdown of ABCC4 significantly reduced the extracellular levels of PGD2 by at least 53% in HMC-1 cells. Moreover, the extracellular levels of PGD2 decreased by at least 20% using the selective ABCC4 inhibitor in the other mast cell line RBL-2H3 cells. Therefore, our results suggest that ABCC4 functions as a PGD2 exporter in HMC-1 cells.

Stimulatory effect on the transport mediated by organic anion transporting polypeptide 2B1.

Drug-drug interaction (DDI) is one of causes of adverse drug events and can result in life-threatening consequences. Organic anion-transporting polypeptide (OATP) 2B1 is a major uptake transporter in the intestine and contributes to transport various clinically used therapeutic agents. The intestine has a high risk of DDI, because it has a special propensity to be exposed to a high concentration of drugs. Thus, understanding drug interaction mediated by OATP2B1 in the absorption process is important for the prevention of adverse drug events, including decrease in the therapeutic effect of co-administered drugs. Acute drug interaction occurs through the direct inhibitory effect on transporters, including OATP2B1. Moreover, some compounds such as clinically used drugs and food components have an acute stimulatory effect on transport of co-administered drugs by OATP2B1. This review summarizes the acute stimulatory effect on the transport mediated by OATP2B1 and discusses the mechanisms of the acute stimulatory effects of compounds. There are two types of acute stimulatory effects, substrate-independent and -dependent interactions on OATP2B1 function. The facilitating translocation of OATP2B1 to the plasma membrane is one of causes for the substrate-independent acute stimulatory effect. On the contrary, the substrate-dependent effect is based on the direct binding to the substrate-binding site or allosteric progesterone-binding site of OATP2B1.

Development of a precise quantitative method for monitoring sirolimus in whole blood using LC/ESI-MS/MS.

Sirolimus is used on patients after solid organ transplantation and on lymphangioleiomyomatosis (LAM) patients, and therapeutic drug monitoring is required in clinical practice. We have previously reported an accurate method for quantitative determination of sirolimus, but its sample preparation step was complicated. In this study, we developed a modified liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for sirolimus quantification. A supported liquid extraction cartridge was used to purify sirolimus from whole blood and ion suppression was mostly prevented. The validation results met the acceptance criteria. This method was compared with the antigen conjugated magnetic immunoassay (ACMIA) and our previously reported method, using whole blood samples from LAM patients. Comparison of the Bland-Altman plots of the currently developed method and the previous method revealed no significant difference between the two methods (mean bias, -2.02%; 95% CI, -7.81-3.78). The values obtained using ACMIA were significantly higher than those obtained using the current method by 13.87% (95% CI, 6.49-21.25) owing to cross-reactivity. The degrees of cross reactivities in LAM patients and in organ transplant patients were similar, and our LC/ESI-MS/MS method precisely measured the blood concentrations of sirolimus.

Risk Factors for Severe Hyponatremia Related to Cisplatin: A Retrospective Case-Control Study.

Onset of severe hyponatremia following cisplatin (CDDP) administration has been previously reported. However, the risk factors associated with hyponatremia still remain unclear. We conducted a retrospective, single-center, case-control study to identify independent risk factors of severe hyponatremia in patients with various types of cancers. Adult patients who received intravenous CDDP administration between January 2012 and December 2017 met the inclusion criteria. The investigators recorded patients' demographics and clinical information retrospectively, and assessed the lowest serum sodium level within 21 d of the first CDDP administration. Risk factors for grade ≥3 hyponatremia were examined via a logistic regression analysis. Among a total of 472 patients, fifty patients (10.6%) developed grade ≥3 hyponatremia. Univariate analysis revealed that age (≥65 years), presence of small cell lung or esophageal cancer, and lower sodium concentrations in the serum (<138 mEq/L) were significantly associated with grade 3 and 4 hyponatremia. Additionally, multivariable logistic regression analysis showed that the presence of small cell lung cancer (adjusted odds ratio, 3.26; 95% confidence interval (CI), 1.07-10.00) and lower sodium concentrations in the serum (<138 mEq/L) (adjusted odds ratio, 6.18; 95%CI, 3.21-11.90) were independent risk factors of grade 3 and 4 hyponatremia. Thus, serum sodium concentrations in patients with these risk factors should be closely monitored after CDDP administration.

Organogermanium suppresses cell death due to oxidative stress in normal human dermal fibroblasts.

Reactive oxygen species (ROS) are very harmful to dermal cells, and it is thus important to develop cosmetics that protect the skin from ROS and other stimuli. Repagermanium is a synthetic water-soluble organogermanium polymer, and in this study, we attempted to visualize the incorporation of germanium into normal human dermal fibroblasts (NHDFs) using isotope microscopy. In addition, the content of 3-(trihydroxygermyl)propanoic acid (THGP), a hydrolyzed monomer of repagermanium, in NHDFs was determined through liquid chromatography mass spectrometry (LC-MS/MS), and the dose-dependent incorporation of THGP was confirmed. We then evaluated the preventive effects of THGP against ROS-induced NHDF death and confirmed the observed preventive effects through gene profiling and expression analysis. The addition of 0.59-5.9 mM THGP reduced cell death resulting from ROS damage caused by the reaction between xanthine oxidase and hypoxanthine and the direct addition of H2O2. Furthermore, this study provides the first demonstration that the effect of THGP was not due to the direct scavenging of ROS, which indicates that the mechanism of THGP differs from that of general antioxidants, such as ascorbic acid. The gene profiling and expression analysis showed that THGP suppressed the expression of the nuclear receptor subfamily 4 group A member 2 (NR4A2) gene, which is related to cell death, and the interleukin 6 (IL6) and chemokine (C-X-C motif) ligand 2 (CXCL2) genes, which are related to the inflammatory response. Furthermore, the production of IL6 induced by H2O2 was suppressed by the THGP treatment. Our data suggest that the preventive effect of THGP against ROS-induced cell death is not due to antioxidant enzymes or ROS scavenging.

Antitumor Effect of a Novel Photodynamic Therapy With Acetylated Glucose-conjugated Chlorin for Gastrointestinal Cancers.

BACKGROUND/AIM: We previously synthesized a glucose-conjugated chlorin compound e6 (G-chlorin e6), and reported that it has very strong antitumor effects. The aim of the present study was to synthesize acetylated glucose-conjugated chlorin (AcN003HP) and evaluate its antitumor effect and excretion. MATERIALS AND METHODS: To evaluate the antitumor effect of AcN003HP, its IC50 was calculated as well as its accumulation in cancer cells was examined by flow cytometry. Confocal microscopy was used to observe the intracellular localization of AcN003HP. The excretion and antitumor effects of AcN003HP were also evaluated in vivo. RESULTS: AcN003HP showed stronger antitumor effects and accumulation into cancer cells compared to talaporfin sodium, a conventional photosensitizer. AcN003HP was localized in the endoplasmic reticulum. In a xenograft tumor mouse model, AcN003HP showed longer excretion time from the body than G-chlorin e6, and photodynamic therapy using AcN003HP showed very strong antitumor effects. CONCLUSION: The safety, improved controllability, and robust antitumor effects suggest AcN003HP as a good next-generation photosensitizer.

Involvement of H+-gradient dependent transporter in PGE2 release from A549 cells.

The purpose of this study was to identify the transporter involved in the release of prostaglandin E2 (PGE2). In the present study, transport assays were conducted using membrane vesicles prepared from human lung adenocarcinoma A549 cells, thus enabling identification of the novel exporter present in A549 cells. PGE2 transport into A549 vesicles was higher in the presence of a proton (H+)-gradient, thus suggesting the involvement of PGE2H+ symporter in PGE2 transport. Results from our experiments showed enhanced PGE2 release in A549 cells in the presence of H+-gradient ([H+]extracellular < [H+]intracellular). Moreover, in vesicular transport assays, H+-gradient-dependent transport of PGE2 did not show saturation up to 500 µM PGE2, and 10 mM aromatic monocarboxylic acids (acetylsalicylic acid, salicylic acid, and p-nitrobenzoic acid) significantly inhibited PGE2 transport by 62-70%. These results suggest, the involvement of monocarboxylate transporters in the H+-gradient-dependent PGE2 export.

[Toward Personalized Cancer Therapy with Oral Molecular-targeted Agents].

Oral molecular-targeted agents are used clinically for the treatment of various types of cancer. However, even when treatment is started at the dosage indicated in the medical package insert, we have experienced many cases in which treatment had to be stopped early owing to the occurrence of serious side effects or an insufficient therapeutic effect. In recent years, a wide range of studies has been conducted on the therapeutic drug monitoring (TDM) of oral molecular-targeted therapeutic agents to prevent serious side effects and maximize the therapeutic effect. In Japan, the TDM of imatinib has been covered by insurance since 2012, and the TDM of sunitinib has been covered since 2018. In contrast, tyrosine kinase inhibitors may have severe side effects, but their TDM is not covered by medical insurance. We aimed to identify a safe, highly effective chemotherapy regimen based on scientific evidence gathered from Japanese patients. We examined the relationship between the plasma concentration of drugs and clinical findings, such as side effects and treatment effects, at our hospital. In this symposium review, we introduce our results based on the treatment of patients with renal cell carcinoma.

A Basic Study of Photodynamic Therapy with Glucose-Conjugated Chlorin e6 Using Mammary Carcinoma Xenografts.

By using the Warburg effect-a phenomenon where tumors consume higher glucose levels than normal cells-on cancer cells to enhance the effect of photodynamic therapy (PDT), we developed a new photosensitizer, glucose-conjugated chlorin e6 (G-Ce6). We analyzed the efficacy of PDT with G-Ce6 against canine mammary carcinoma (CMC) in vitro and in vivo. The pharmacokinetics of G-Ce6 at 2, 5, and 20 mg/kg was examined in normal dogs, whereas its intracellular localization, concentration, and photodynamic effects were investigated in vitro using CMC cells (SNP cells). G-Ce6 (10 mg/kg) was administered in vivo at 5 min or 3 h before laser irradiation to SNP tumor-bearing murine models. The in vitro study revealed that G-Ce6 was mainly localized to the lysosomes. Cell viability decreased in a G-Ce6 concentration- and light intensity-dependent manner in the PDT group. Cell death induced by PDT with G-Ce6 was not inhibited by an apoptosis inhibitor. In the in vivo study, 5-min-interval PDT exhibited greater effects than 3-h-interval PDT. The mean maximum blood concentration and half-life of G-Ce6 (2 mg/kg) were 15.19 ± 4.44 µg/mL and 3.02 ± 0.58 h, respectively. Thus, 5-min-interval PDT with G-Ce6 was considered effective against CMC.

Gut microbiome-derived phenyl sulfate contributes to albuminuria in diabetic kidney disease.

Diabetic kidney disease is a major cause of renal failure that urgently necessitates a breakthrough in disease management. Here we show using untargeted metabolomics that levels of phenyl sulfate, a gut microbiota-derived metabolite, increase with the progression of diabetes in rats overexpressing human uremic toxin transporter SLCO4C1 in the kidney, and are decreased in rats with limited proteinuria. In experimental models of diabetes, phenyl sulfate administration induces albuminuria and podocyte damage. In a diabetic patient cohort, phenyl sulfate levels significantly correlate with basal and predicted 2-year progression of albuminuria in patients with microalbuminuria. Inhibition of tyrosine phenol-lyase, a bacterial enzyme responsible for the synthesis of phenol from dietary tyrosine before it is metabolized into phenyl sulfate in the liver, reduces albuminuria in diabetic mice. Together, our results suggest that phenyl sulfate contributes to albuminuria and could be used as a disease marker and future therapeutic target in diabetic kidney disease.

Estimation of Blood Sirolimus Concentration Based on Tacrolimus Concentration/Dose Normalized by Body Weight Ratio in Lung Transplant Patients.

BACKGROUND: Sirolimus and tacrolimus require accurate drug dosing based on their target blood levels to produce better clinical outcomes, specifically, the avoidance of drug-induced adverse effects and the maintenance of efficacy. However, because the ideal dose of sirolimus and the schedule for measuring its blood levels are unclear in lung transplant patients, an index is required for estimating sirolimus blood concentrations. The aim of this work is to study the correlation between the trough concentration/dose normalized by body weight (C0/D) ratios of sirolimus and tacrolimus in lung transplant patients. METHODS: Thirteen lymphangiomyomatosis patients who underwent lung transplantation and were treated with sirolimus and tacrolimus from February 2015 to July 2018 were divided into 2 groups, one receiving twice-daily (TD, n = 6) and the other once-daily (OD, n = 7) tacrolimus formulations. The correlation between the C0/D ratio of sirolimus and patient background was evaluated using Spearman's rank correlation coefficient. Correlations between sirolimus and tacrolimus C0/D ratios or doses were analyzed by single regression analysis. RESULTS: Significant correlations were found between the C0/D ratios of sirolimus and tacrolimus. The regression equations from the initial data of TD and OD groups at steady state were y = 1.880x + 32.636 (adjusted R = 0.743, P = 0.017) and y = 1.684x + 38.816 (adjusted R = 0.919, P < 0.001), respectively. In addition, the regression equations from all data of TD and OD groups were y = 1.883x + 4.170 (adjusted R = 0.546, P < 0.001) and y = 1.950x + 43.188 (adjusted R = 0.898, P < 0.001), respectively. A significant correlation between the dosage of sirolimus and tacrolimus was observed only in the OD group, with relatively low accuracy. CONCLUSIONS: Blood sirolimus concentrations can be estimated using the C0/D ratio of tacrolimus, suggesting that the C0/D ratio of tacrolimus is an index of required sirolimus dosage and the frequency of blood sirolimus concentration measurements.