A role for mutations in AK9 and other genes affecting ependymal cells in idiopathic normal pressure hydrocephalus.

Idiopathic normal pressure hydrocephalus (iNPH) is an enigmatic neurological disorder that develops after age 60 and is characterized by gait difficulty, dementia, and incontinence. Recently, we reported that heterozygous CWH43 deletions may cause iNPH. Here, we identify mutations affecting nine additional genes (AK9, RXFP2, PRKD1, HAVCR1, OTOG, MYO7A, NOTCH1, SPG11, and MYH13) that are statistically enriched among iNPH patients. The encoded proteins are all highly expressed in choroid plexus and ependymal cells, and most have been associated with cilia. Damaging mutations in AK9, which encodes an adenylate kinase, were detected in 9.6% of iNPH patients. Mice homozygous for an iNPH-associated AK9 mutation displayed normal cilia structure and number, but decreased cilia motility and beat frequency, communicating hydrocephalus, and balance impairment. AK9+/- mice displayed normal brain development and behavior until early adulthood, but subsequently developed communicating hydrocephalus. Together, our findings suggest that heterozygous mutations that impair ventricular epithelial function may contribute to iNPH.

Feasibility of transcranial Doppler to evaluate vasculopathy among survivors of childhood brain tumors exposed to cranial radiation therapy.

BACKGROUND: The ability of transcranial Doppler (TCD) to detect asymptomatic cerebrovascular disease among childhood brain tumor survivors following exposure to cranial radiation therapy has not been established. METHODS: Survivors of childhood brain tumors, more than 3 years since diagnosis and exposed to greater than 30 Gy cranial radiation, underwent a history and physical exam, laboratory biomarkers of cerebrovascular disease (cholesterol, high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), high-sensitivity CRP, hemoglobin A1C, apoprotein A, and apoprotein B), and a TCD evaluation of their cerebral arteries. RESULTS: In all 165 cerebral arteries from 13 patients (medulloblastoma = 10; germ cell tumor = 3; females = 5; mean age at diagnosis = 8.0 years; mean age at time of study = 20.9 years) were examined. Twenty-eight of 165 (17%) were considered abnormal by pre-specified criteria. Total 114 cerebral arteries from 13 patients were assessed for greater than 50% stenosis velocities. Arteries most likely to be considered abnormal included the distal bilateral vertebral arteries (right 38%, left 30%), basilar artery 30%, bilateral siphon internal carotid arteries (right 30%, left 23%), bilateral middle cerebral arteries (23% bilaterally), and bilateral anterior cerebral arteries (7% bilaterally). Two vessels had mean flow velocities consistent with ≥ $ \ge $ 50% stenosis (1.8%). No vessels were found to have greater than 80% stenosis. CONCLUSIONS: TCD may be a useful and practical tool to examine asymptomatic cerebrovascular disease among childhood brain tumor survivors after exposure to cranial radiation therapy. Posterior circulation vessels appear to have the highest burden of disease in this group of brain tumor survivors, a majority of whom had medulloblastoma.

Increased plasmin-mediated proteolysis of L1CAM in a mouse model of idiopathic normal pressure hydrocephalus.

Idiopathic normal pressure hydrocephalus (iNPH) is a common neurological disorder that is characterized by enlarged cerebral ventricles, gait difficulty, incontinence, and dementia. iNPH usually develops after the sixth decade of life in previously asymptomatic individuals. We recently reported that loss-of-function deletions in CWH43 lead to the development of iNPH in a subgroup of patients, but how this occurs is poorly understood. Here, we show that deletions in CWH43 decrease expression of the cell adhesion molecule, L1CAM, in the brains of CWH43 mutant mice and in human HeLa cells harboring a CWH43 deletion. Loss-of-function mutations in L1CAM are a common cause of severe neurodevelopmental defects that include congenital X-linked hydrocephalus. Mechanistically, we find that CWH43 deletion leads to decreased N-glycosylation of L1CAM, decreased association of L1CAM with cell membrane lipid microdomains, increased L1CAM cleavage by plasmin, and increased shedding of cleaved L1CAM in the cerebrospinal fluid. CWH43 deletion also decreased L1CAM nuclear translocation, suggesting decreased L1CAM intracellular signaling. Importantly, the increase in L1CAM cleavage occurred primarily in the ventricular and subventricular zones where brain CWH43 is most highly expressed. Thus, CWH43 deletions may contribute to adult-onset iNPH by selectively downregulating L1CAM in the ventricular and subventricular zone.

Heterozygous FOXJ1 Mutations Cause Incomplete Ependymal Cell Differentiation and Communicating Hydrocephalus.

Heterozygous mutations affecting FOXJ1, a transcription factor governing multiciliated cell development, have been associated with obstructive hydrocephalus in humans. However, factors that disrupt multiciliated ependymal cell function often cause communicating hydrocephalus, raising questions about whether FOXJ1 mutations cause hydrocephalus primarily by blocking cerebrospinal fluid (CSF) flow or by different mechanisms. Here, we show that heterozygous FOXJ1 mutations are also associated with communicating hydrocephalus in humans and cause communicating hydrocephalus in mice. Disruption of one Foxj1 allele in mice leads to incomplete ependymal cell differentiation and communicating hydrocephalus. Mature ependymal cell number and motile cilia number are decreased, and 12% of motile cilia display abnormal axonemes. We observed decreased microtubule attachment to basal bodies, random localization and orientation of basal body patches, loss of planar cell polarity, and a disruption of unidirectional CSF flow. Thus, heterozygous FOXJ1 mutations impair ventricular multiciliated cell differentiation, thereby causing communicating hydrocephalus. CSF flow obstruction may develop secondarily in some patients harboring FOXJ1 mutations. Heterozygous FOXJ1 mutations impair motile cilia structure and basal body alignment, thereby disrupting CSF flow dynamics and causing communicating hydrocephalus.

Environmental DNA as an emerging tool in botanical research.

Over the past quarter century, environmental DNA (eDNA) has been ascendant as a tool to detect, measure, and monitor biodiversity (species and communities), as a means of elucidating biological interaction networks, and as a window into understanding past patterns of biodiversity. However, only recently has the potential of eDNA been realized in the botanical world. Here we synthesize the state of eDNA applications in botanical systems with emphases on aquatic, ancient, contemporary sediment, and airborne systems, and focusing on both single-species approaches and multispecies community metabarcoding. Further, we describe how abiotic and biotic factors, taxonomic resolution, primer choice, spatiotemporal scales, and relative abundance influence the utilization and interpretation of airborne eDNA results. Lastly, we explore several areas and opportunities for further development of eDNA tools for plants, advancing our knowledge and understanding of the efficacy, utility, and cost-effectiveness, and ultimately facilitating increased adoption of eDNA analyses in botanical systems.

The effects of aneurysmal subarachnoid hemorrhage on cerebral vessel diameter and flow velocity.

BACKGROUND: Transcranial Doppler flow velocity is used to monitor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Generally, blood flow velocities appear inversely related to the square of vessel diameter representing local fluid dynamics. However, studies of flow velocity-diameter relationships are few, and may identify vessels for which diameter changes are better correlated with Doppler velocity. We therefore studied a large retrospective cohort with concurrent transcranial Doppler velocities and angiographic vessel diameters. METHODS: This is a single-site, retrospective, cohort study of adult patients with aneurysmal subarachnoid hemorrhage, approved by the UT Southwestern Medical Center Institutional Review Board. Study inclusion required transcranial Doppler measurements within 1.1, R2>0.9). Furthermore, velocity and diameter changed (P<0.033) consistent with the signature time course of cerebral vasospasm. CONCLUSIONS: These results suggest that middle cerebral artery velocity-diameter relationships are most influenced by local fluid dynamics, which supports these vessels as preferred endpoints in Doppler detection of cerebral vasospasm. Other vessels showed less influence of local fluid dynamics, pointing to greater role of factors outside the local vessel segment in determining flow velocity.

The history of antibiotic irrigation and prophylaxis in operative neurotrauma: perpetuation of military care in civilian settings.

The benefit of antibiotic irrigation for prophylaxis against wound infections, not only for traumatic cranial injuries but also in elective neurosurgical care, has recently been called into question. Several articles have cast doubt on the utility of topical antibiotics, and recently, bacitracin irrigation was made unavailable in some US markets. The pervasive nature of antibiotic irrigation, considering the lack of evidence supporting its use, led the authors to question when and how neurosurgeons started using antibiotic irrigation in cranial neurosurgery. Through a review of historical literature, they highlight the adoption of antibiotic irrigation as it began in battlefield surgical practice, gradually leading to the modern concept of antibiotic prophylaxis in civilian and military care.

Delivering Therapeutics to Glioblastoma: Overcoming Biological Constraints.

Glioblastoma multiforme is the most lethal intrinsic brain tumor. Even with the existing treatment regimen of surgery, radiation, and chemotherapy, the median survival time is only 15-23 months. The invasive nature of this tumor makes its complete removal very difficult, leading to a high recurrence rate of over 90%. Drug delivery to glioblastoma is challenging because of the molecular and cellular heterogeneity of the tumor, its infiltrative nature, and the blood-brain barrier. Understanding the critical characteristics that restrict drug delivery to the tumor is necessary to develop platforms for the enhanced delivery of effective treatments. In this review, we address the impact of tumor invasion, the molecular and cellular heterogeneity of the tumor, and the blood-brain barrier on the delivery and distribution of drugs using potential therapeutic delivery options such as convection-enhanced delivery, controlled release systems, nanomaterial systems, peptide-based systems, and focused ultrasound.

Anhydrous Ammonia Chemical Release - Lake County, Illinois, April 2019.

On April 25, 2019, a farm tractor towing two 2-ton ammonia tanks on a county road in Lake County, Illinois, experienced a mechanical failure that resulted in the release of anhydrous ammonia, a colorless, pungent, irritating gas that can cause severe respiratory and ocular damage (1). Approximately 80% of anhydrous ammonia produced in the United States is used as a fertilizer in agriculture (1). Eighty-three persons, including first responders, motorists, and neighborhood residents, were evaluated at area hospitals because of exposure to the gas. Two weeks after the release, the Agency for Toxic Substances and Disease Registry (ATSDR) and CDC's National Center for Environmental Health (NCEH) collaborated with the Lake County Health Department and the Illinois Department of Public Health on an investigation using ATSDR's Assessment of Chemical Exposures program to describe the release, review the emergency response, and determine health effects associated with the exposure. First responders, community residents, and hospital personnel reported communication challenges related to the nature of the gas release and effective protective measures. Among the 83 persons evaluated at six area hospitals for effects of the chemical release, 14 (17%) were hospitalized, including eight (10%) who were admitted to the intensive care unit (ICU), seven (8%) of whom required endotracheal intubation and mechanical ventilation; no deaths occurred. In addition, ICU health care providers experienced symptoms of secondary exposure. The National Institute for Occupational Safety and Health's Emergency Responder Health Monitoring and Surveillance Program has specific recommendations and tools to protect responders during all phases of a response (2). Hospitals also need to review institutional policies and procedures for chemical mass casualty events, including decontamination (3). Prompt and correct identification of hazardous material (hazmat) events, and clear communication among responding entities, including on-scene and hospital responders, is important to ensure effective response after a chemical release.

Salvage re-irradiation for recurrent high-grade glioma and comparison to bevacizumab alone.

While salvage re-irradiation is often used for recurrent high-grade glioma (HGG), there have been few comparisons between various re-radiation dose/fractionation schedules or with bevacizumab alone. We analyzed patients with recurrent HGG who received re-irradiation at Dana-Farber Cancer Institute and Brigham and Women's Hospital from 2010 to 2014 (n = 67), as well as those who received bevacizumab alone (n = 177). Cox proportional hazards modeling was used to examine factors associated with overall survival (OS). Propensity score modeling was used to compare survival after re-irradiation vs. bevacizumab alone. Median time from initial diagnosis to re-irradiation was 31.4 months. The most common re-irradiation dose/fractionations used were 6 Gy × 5 (36%), 3.5 Gy × 10 (21%), 2.67 Gy × 15 (15%), and 18-20 Gy × 1 (15%). No early or late toxicities >grade 2 were observed. Median PFS and OS after re-irradiation were 4.8 and 10.7 months, respectively. Number of progressions prior to re-irradiation (adjusted hazard ratio [AHR] 1.6; 95% CI, 1.1-2.3; p = .007), and recurrence in a new brain location (vs. local-only; AHR 7.4; 95% CI, 2.4-23.1; p < .001) were associated with OS; dose/fractionation was not. Compared with bevacizumab alone, re-irradiated patients had a non-significant increase in OS (HR 0.80; 95% CI, 0.53-1.23; P = .31). Among patients with a local-only recurrence, there was a trend towards longer median OS after re-irradiation compared to bevacizumab alone (12.4 vs. 8.0 months; p = .12). Survival after re-irradiation for recurrent HGG appears independent of dose/fractionation and compares favorably with bevacizumab alone.

In vitro and physiologically-based pharmacokinetic based assessment of drug-drug interaction potential of canagliflozin.

AIMS: Canagliflozin is a recently approved drug for use in the treatment of type 2 diabetes. The potential for canagliflozin to cause clinical drug-drug interactions (DDIs) was assessed. METHODS: DDI potential of canagliflozin was investigated using in vitro test systems containing drug metabolizing enzymes or transporters. Basic predictive approaches were applied to determine potential interactions in vivo. A physiologically-based pharmacokinetic (PBPK) model was developed and clinical DDI simulations were performed to determine the likelihood of cytochrome P450 (CYP) inhibition by canagliflozin. RESULTS: Canagliflozin was primarily metabolized by uridine 5'-diphospho-glucuronosyltransferase 1A9 and 2B4 enzymes. Canagliflozin was a substrate of efflux transporters (P-glycoprotein, breast cancer resistance protein and multidrug resistance-associated protein-2) but was not a substrate of uptake transporters (organic anion transporter polypeptide isoforms OATP1B1, OATP1B3, organic anion transporters OAT1 and OAT3, and organic cationic transporters OCT1, and OCT2). In inhibition assays, canagliflozin was shown to be a weak in vitro inhibitor (IC50 ) of CYP3A4 (27 µmol l -1 , standard error [SE] 4.9), CYP2C9 (80 µmol l -1 , SE 8.1), CYP2B6 (16 µmol l-1 , SE 2.1), CYP2C8 (75 µmol l -1 , SE 6.4), P-glycoprotein (19.3 µmol l -1 , SE 7.2), and multidrug resistance-associated protein-2 (21.5 µmol l -1 , SE 3.1). Basic models recommended in DDI guidelines (US Food & Drug Administration and European Medicines Agency) predicted moderate to low likelihood of interaction for these CYPs and efflux transporters. PBPK DDI simulations of canagliflozin with CYP probe substrates (simvastatin, S-warfarin, bupropion, repaglinide) did not show relevant interaction in humans since mean areas under the concentration-time curve and maximum plasma concentration ratios for probe substrates with and without canagliflozin and its 95% CIs were within 0.80-1.25. CONCLUSIONS: In vitro DDI followed by a predictive or PBPK approach was applied to determine DDI potential of canagliflozin. Overall, canagliflozin is neither a perpetrator nor a victim of clinically important interactions.

Functional genomic analysis of chromosomal aberrations in a compendium of 8000 cancer genomes.

A large database of copy number profiles from cancer genomes can facilitate the identification of recurrent chromosomal alterations that often contain key cancer-related genes. It can also be used to explore low-prevalence genomic events such as chromothripsis. In this study, we report an analysis of 8227 human cancer copy number profiles obtained from 107 array comparative genomic hybridization (CGH) studies. Our analysis reveals similarity of chromosomal arm-level alterations among developmentally related tumor types as well as a number of co-occurring pairs of arm-level alterations. Recurrent ("pan-lineage") focal alterations identified across diverse tumor types show an enrichment of known cancer-related genes and genes with relevant functions in cancer-associated phenotypes (e.g., kinase and cell cycle). Tumor type-specific ("lineage-restricted") alterations and their enriched functional categories were also identified. Furthermore, we developed an algorithm for detecting regions in which the copy number oscillates rapidly between fixed levels, indicative of chromothripsis. We observed these massive genomic rearrangements in 1%-2% of the samples with variable tumor type-specific incidence rates. Taken together, our comprehensive view of copy number alterations provides a framework for understanding the functional significance of various genomic alterations in cancer genomes.

Aggressive medical treatment with or without stenting in high-risk patients with intracranial artery stenosis (SAMMPRIS): the final results of a randomised trial.

BACKGROUND: Early results of the Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis trial showed that, by 30 days, 33 (14·7%) of 224 patients in the stenting group and 13 (5·8%) of 227 patients in the medical group had died or had a stroke (percentages are product limit estimates), but provided insufficient data to establish whether stenting offered any longer-term benefit. Here we report the long-term outcome of patients in this trial. METHODS: We randomly assigned (1:1, stratified by centre with randomly permuted block sizes) 451 patients with recent transient ischaemic attack or stroke related to 70-99% stenosis of a major intracranial artery to aggressive medical management (antiplatelet therapy, intensive management of vascular risk factors, and a lifestyle-modification programme) or aggressive medical management plus stenting with the Wingspan stent. The primary endpoint was any of the following: stroke or death within 30 days after enrolment, ischaemic stroke in the territory of the qualifying artery beyond 30 days of enrolment, or stroke or death within 30 days after a revascularisation procedure of the qualifying lesion during follow-up. Primary endpoint analysis of between-group differences with log-rank test was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT 00576693. FINDINGS: During a median follow-up of 32·4 months, 34 (15%) of 227 patients in the medical group and 52 (23%) of 224 patients in the stenting group had a primary endpoint event. The cumulative probability of the primary endpoints was smaller in the medical group versus the percutaneous transluminal angioplasty and stenting (PTAS) group (p=0·0252). Beyond 30 days, 21 (10%) of 210 patients in the medical group and 19 (10%) of 191 patients in the stenting group had a primary endpoint. The absolute differences in the primary endpoint rates between the two groups were 7·1% at year 1 (95% CI 0·2 to 13·8%; p=0·0428), 6·5% at year 2 (-0·5 to 13·5%; p=0·07) and 9·0% at year 3 (1·5 to 16·5%; p=0·0193). The occurrence of the following adverse events was higher in the PTAS group than in the medical group: any stroke (59 [26%] of 224 patients vs 42 [19%] of 227 patients; p=0·0468) and major haemorrhage (29 [13%]of 224 patients vs 10 [4%] of 227 patients; p=0·0009). INTERPRETATION: The early benefit of aggressive medical management over stenting with the Wingspan stent for high-risk patients with intracranial stenosis persists over extended follow-up. Our findings lend support to the use of aggressive medical management rather than PTAS with the Wingspan system in high-risk patients with atherosclerotic intracranial arterial stenosis. FUNDING: National Institute of Neurological Disorders and Stroke (NINDS) and others.

Salvage whole brain radiotherapy or stereotactic radiosurgery after initial stereotactic radiosurgery for 1-4 brain metastases.

Patients with limited brain metastases are often candidates for stereotactic radiosurgery (SRS) or whole brain radiotherapy (WBRT). Among patients who receive SRS, the likelihood and timing of salvage WBRT or SRS remains unclear. We examined rates of salvage WBRT or SRS among 180 patients with 1-4 newly diagnosed brain metastases who received index SRS from 2008-2013. Competing risks multivariable analysis was used to examine factors associated with time to WBRT. Patients had non-small cell lung (53 %), melanoma (23 %), breast (10 %), renal (6 %), or other (8 %) cancers. Median age was 62 years. Patients received index SRS to 1 (60 %), 2 (21 %), 3 (13 %), or 4 (7 %) brain metastases. Median survival after SRS was 9.7 months (range, 0.3-67.6 months). No further brain-directed radiotherapy was delivered after index SRS in 55 % of patients. Twenty-seven percent of patients ever received salvage WBRT, and 30 % ever received salvage SRS; 12 % of patients received both salvage WBRT and salvage SRS. Median time to salvage WBRT or salvage SRS were 5.6 and 6.1 months, respectively. Age ≤60 years (adjusted hazard ratio [AHR] = 2.80; 95 % CI 1.05-7.51; P = 0.04) and controlled/absent extracranial disease (AHR = 6.76; 95 % CI 1.60-28.7; P = 0.01) were associated with shorter time to salvage WBRT. Isolated brain progression caused death in only 11 % of decedents. In summary, most patients with 1-4 brain metastases receiving SRS never require salvage WBRT or SRS, and the remainder do not require salvage treatment for a median of 6 months.

Incidence, risk factors, and reasons for hospitalization among glioblastoma patients receiving chemoradiation.

Despite a high symptom burden, little is known about the incidence or predictors of hospitalization among glioblastoma patients, including risks during chemoradiation (CRT). We studied 196 consecutive newly diagnosed glioblastoma patients treated at our institution from 2006-2010. Toxicity data were reviewed during and after the CRT phase, defined as the period between diagnosis and 6 weeks after radiotherapy completion. Logistic regression and proportional hazards modeling identified predictors of hospitalization and overall survival (OS). Median age was 59 years (range, 23-90) and 83 % had Karnofsky performance status (KPS) score ≥ 70. Twenty-six percent of patients underwent gross total resection, 77 % received ≥ 59.4 Gy of radiotherapy, and 89 % received concurrent temozolomide. Median OS was 15.6 months (IQR, 8.5-26.8 months). Forty-three percent of patients were hospitalized during the CRT phase; OS was 10.7 vs. 17.8 months for patients who were vs. were not hospitalized, respectively (P < .001). Nearly half of the hospitalizations were due to generalized weakness (17 % of hospitalizations), seizures (16 %), or venous thromboembolism (13 %). On multivariate analysis, age (odds ratio [OR], 1.03; 95 % CI, 1.002-1.060; P = .034) and KPS (OR, 0.95; 95 % CI, 0.93-0.97; P < .001) were associated with risk of hospitalization. Hospitalization during the CRT phase was associated with decreased OS (adjusted hazard ratio, 1.47; 95 % CI, 1.01-2.13; P = .043), after adjustment for known prognostic factors. Hospitalization during the CRT phase is common among glioblastoma patients in the temozolomide era and is associated with shorter overall survival.

Successful integration of nonclinical and clinical findings in interpreting the clinical relevance of rodent neoplasia with a new chemical entity.

Canagliflozin, a sodium glucose co-transporter 2 (SGLT2) inhibitor, has been developed for the treatment of adults with type 2 diabetes mellitus (T2DM). During the phase 3 program, treatment-related pheochromocytomas, renal tubular tumors, and testicular Leydig cell tumors were reported in the 2-year rat toxicology study. Treatment-related tumors were not seen in the 2-year mouse study. A cross-functional, mechanism-based approach was undertaken to determine whether the mechanisms responsible for tumorigenesis in the rat were of relevance to humans. Based on findings from nonclinical and clinical studies, the treatment-related tumors observed in rats were not deemed to be of clinical relevance. Here, we describe the scientific and regulatory journey from learning of the 2-year rat study findings to the approval of canagliflozin for the treatment of T2DM.

Stenting versus aggressive medical therapy for intracranial arterial stenosis.

BACKGROUND: Atherosclerotic intracranial arterial stenosis is an important cause of stroke that is increasingly being treated with percutaneous transluminal angioplasty and stenting (PTAS) to prevent recurrent stroke. However, PTAS has not been compared with medical management in a randomized trial. METHODS: We randomly assigned patients who had a recent transient ischemic attack or stroke attributed to stenosis of 70 to 99% of the diameter of a major intracranial artery to aggressive medical management alone or aggressive medical management plus PTAS with the use of the Wingspan stent system. The primary end point was stroke or death within 30 days after enrollment or after a revascularization procedure for the qualifying lesion during the follow-up period or stroke in the territory of the qualifying artery beyond 30 days. RESULTS: Enrollment was stopped after 451 patients underwent randomization, because the 30-day rate of stroke or death was 14.7% in the PTAS group (nonfatal stroke, 12.5%; fatal stroke, 2.2%) and 5.8% in the medical-management group (nonfatal stroke, 5.3%; non-stroke-related death, 0.4%) (P=0.002). Beyond 30 days, stroke in the same territory occurred in 13 patients in each group. Currently, the mean duration of follow-up, which is ongoing, is 11.9 months. The probability of the occurrence of a primary end-point event over time differed significantly between the two treatment groups (P=0.009), with 1-year rates of the primary end point of 20.0% in the PTAS group and 12.2% in the medical-management group. CONCLUSIONS: In patients with intracranial arterial stenosis, aggressive medical management was superior to PTAS with the use of the Wingspan stent system, both because the risk of early stroke after PTAS was high and because the risk of stroke with aggressive medical therapy alone was lower than expected. (Funded by the National Institute of Neurological Disorders and Stroke and others; SAMMPRIS ClinicalTrials.gov number, NCT00576693.).

Metabolism and excretion of canagliflozin in mice, rats, dogs, and humans.

Canagliflozin is an oral antihyperglycemic agent used for the treatment of type 2 diabetes mellitus. It blocks the reabsorption of glucose in the proximal renal tubule by inhibiting the sodium-glucose cotransporter 2. This article describes the in vivo biotransformation and disposition of canagliflozin after a single oral dose of [(14)C]canagliflozin to intact and bile duct-cannulated (BDC) mice and rats and to intact dogs and humans. Fecal excretion was the primary route of elimination of drug-derived radioactivity in both animals and humans. In BDC mice and rats, most radioactivity was excreted in bile. The extent of radioactivity excreted in urine as a percentage of the administered [(14)C]canagliflozin dose was 1.2%-7.6% in animals and approximately 33% in humans. The primary pathways contributing to the metabolic clearance of canagliflozin were oxidation in animals and direct glucuronidation of canagliflozin in humans. Unchanged canagliflozin was the major component in systemic circulation in all species. In human plasma, two pharmacologically inactive O-glucuronide conjugates of canagliflozin, M5 and M7, represented 19% and 14% of total drug-related exposure and were considered major human metabolites. Plasma concentrations of M5 and M7 in mice and rats from repeated dose safety studies were lower than those in humans given canagliflozin at the maximum recommended dose of 300 mg. However, biliary metabolite profiling in rodents indicated that mouse and rat livers had significant exposure to M5 and M7. Pharmacologic inactivity and high water solubility of M5 and M7 support glucuronidation of canagliflozin as a safe detoxification pathway.

Oxidative stress/reactive metabolite gene expression signature in rat liver detects idiosyncratic hepatotoxicants.

Previously we reported a gene expression signature in rat liver for detecting a specific type of oxidative stress (OS) related to reactive metabolites (RM). High doses of the drugs disulfiram, ethinyl estradiol and nimesulide were used with another dozen paradigm OS/RM compounds, and three other drugs flutamide, phenacetin and sulindac were identified by this signature. In a second study, antiepileptic drugs were compared for covalent binding and their effects on OS/RM; felbamate, carbamazepine, and phenobarbital produced robust OS/RM gene expression. In the present study, liver RNA samples from drug-treated rats from more recent experiments were examined for statistical fit to the OS/RM signature. Of all 97 drugs examined, in addition to the nine drugs noted above, 19 more were identified as OS/RM-producing compounds-chlorpromazine, clozapine, cyproterone acetate, dantrolene, dipyridamole, glibenclamide, isoniazid, ketoconazole, methapyrilene, naltrexone, nifedipine, sulfamethoxazole, tamoxifen, coumarin, ritonavir, amitriptyline, valproic acid, enalapril, and chloramphenicol. Importantly, all of the OS/RM drugs listed above have been linked to idiosyncratic hepatotoxicity, excepting chloramphenicol, which does not have a package label for hepatotoxicity, but does have a black box warning for idiosyncratic bone marrow suppression. Most of these drugs are not acutely toxic in the rat. The OS/RM signature should be useful to avoid idiosyncratic hepatotoxicity of drug candidates.