Now showing items 1-20 of 273

    • Mapping Expanded Prostate Cancer Index Composite (EPIC) Questionnaire to EuroQoL-5D (EQ-5D) Utility Weights to Inform Economic Evaluations for Prostate Cancer

      Khairnar, Rahul; Palumbo, Francis Bernard, 1945- (2020)
      OBJECTIVES: To develop a mapping algorithm to obtain EuroQoL-5D-3L (EQ5D) health utilities from Expanded Prostate Cancer Index Composite (EPIC) questionnaire. METHODS: This mapping study utilized baseline data from an international, multicenter, randomized controlled trial (NCT00331773) of patients with low-risk prostate cancer. Patient health-related quality-of-life (HRQoL) data were collected using EPIC and health utilities were obtained using EQ5D. Data were divided into an estimation sample (n=765, 70%) and a validation sample (n=327, 30%). The relationship between the instruments was estimated using ordinary least squares (OLS), Tobit, and two-part models. Five-fold cross-validation (in-sample) was used to compare the predictive performance of the estimated models. Final models were selected based on root mean square error (RMSE). OLS models using baseline cross-sectional data, combined data from all assessment periods, and random effects (RE) models that explicitly model the longitudinal nature of the data were estimated to compare predictive ability of algorithms derived from cross-sectional and longitudinal data. Longitudinal predictive performance of OLS models derived using baseline data was examined in the post-intervention data. RESULTS: A total of 565 patients in the estimation sample had complete information on both EPIC and EQ5D questionnaires at baseline. Mean observed EQ5D utility was 0.90±0.13 (range: 0.28-1) with 55% of patients in full health. Low to moderate correlations were found between EQ5D utility and urinary (r=0.38), bowel (r=0.34) and hormonal (r=0.55) domains of EPIC; sexual domain was weakly correlated (r=0.18) with EQ5D utility. OLS models outperformed their counterpart models for all pre-determined model specifications. The best model fit was: “EQ5D utility = 0.248541 + 0.000748*(Urinary Function) + 0.001134*(Urinary Bother) + 0.000968*(Hormonal Function) + 0.004404*(Hormonal Bother) – 0.376487*(Zubrod) + 0.003562*(Urinary Function*Zubrod)”; RMSE was 0.10462. When comparing cross-sectional vs. longitudinal data, a mapping algorithm obtained using combined EPIC subdomain data outperformed other model types. Mean absolute differences (MDs) between reported and predicted were low in general and decreased as the time of assessment increased. CONCLUSIONS: This study identified mapping algorithms to generate EQ5D utilities from EPIC domain or sub-domain scores, with satisfactory longitudinal predictive performance. The study results will help estimate quality-adjusted life-years in future economic evaluations of prostate cancer treatments.
    • Early Symptom Improvement as a Predictor of Antidepressant Response in Children and Adolescents Diagnosed with Depression: Translating Evidence from Randomized Controlled Trials to Community Practice

      Spence, O'Mareen; dosReis, Susan (2020)
      Statement of the Problem: A common problem among children and adolescents diagnosed with depression who receive care in community settings is that antidepressant regimen changes such as psychotropic augmentation may occur soon after starting treatment. This raises the question as to whether such changes are implemented among youth who would otherwise respond to the antidepressant. Thus, the overarching objectives of this dissertation were to 1) distinguish early in treatment children and adolescents who are likely to respond, and 2) empirically evaluate the association between predicted response and psychotropic augmentation or switching in real world settings. Summary of Methods: Using randomized clinical trial (RCT) data, this research applied a Bayesian approach to predict the likelihood of initial (12 week) and sustained (18 week) response to treatment as a function of early changes in depressive symptoms (i.e. mood, somatic, subjective and behavioral) and other demographic and clinical factors. An innovative application of combined sample multiple imputations (CSMI) was used to estimate the 12-week predicted probability of response among commercially insured adolescents who received care in real-world settings. Each adolescent received a probability of treatment response, which was then used to compare the odds of psychotropic augmentation or switch. Results: Early changes in mood and somatic symptoms within the first six weeks of treatment are primary predictors of initial (at 12 weeks) and sustained (at 18 weeks) response to an antidepressant. Baseline depression severity is an important prognostic factor for initial response, and additional, though minimal improvement, in somatic symptoms from weeks 6 to 12 is indicative of sustained response. In a highly selected cohort of adolescents receiving care in community settings, an augmentation or switch occurred similarly among adolescents with a high versus low likelihood of responding to fluoxetine. Conclusion: The results suggest that other factors beyond expected antidepressant response (or lack thereof) might influence current treatment practices. Our findings have clinical and public health implications that support measurement-based care in pediatric depression. Our application of CSMI highlights several key areas of consideration for future pharmacoepidemiologic research aimed at translating RCT evidence to real world data to better understand clinical practices patterns.
    • Follicular Lymphoma Stage at Diagnosis: Determinants, Prediction from Administrative Claims Data and Impact on Healthcare Costs

      Albarmawi, Husam; Onukwugha, Eberechukwu (2020)
      Introduction: Follicular lymphoma (FL) stage is an important determinant of survival, treatment options and treatment outcomes. However, the determinants of advanced FL, defined as Ann Arbor stages III and IV, and its impact on the economic burden of FL are unknown. Moreover, for studies that rely on administrative claims data, it is not clear if advanced FL can be accurately predicted from this data source. Methods: Using the linked Surveillance, Epidemiology, and End Results-Medicare database we identified patients newly diagnosed with FL. We estimated a modified Poisson regression to explore the effect of pre-diagnosis healthcare resource utilization patterns and baseline county-level factors on FL stage. We estimated the 1-year and 5-year incremental costs of stages II-IV compared to stage I using generalized linear models. To predict FL stage from claims data, we developed and tested two random forests models. Results: We identified 11,078 patients diagnosed in 2000-2013. Half of the sample had advanced FL. Higher counts of specialist physician visits in the 3 years pre-diagnosis were associated with lower risk of advanced FL (4th quartile vs. 1st quartile: Relative Risk [RR]=0.92; 95% CI=0.86–0.99). The risk of advanced FL was 8% lower among women receiving screening mammography compared to men (RR=0.92; 95% CI=0.88–0.97). Living in counties designated as health professional shortage areas (HPSA) was associated with 7% increased risk of advanced FL (RR=1.07; 95% CI=1.00–1.14, p=0.049). In 2004-2009, FL patients with stages II, III and IV had statistically higher 1-year ($14,911; $15,106; $24,639, respectively, p<0.01) and 5-year costs ($21,590; $23,599; $34,968, respectively, p<0.01) compared to stage I patients. The random forests models exhibited poor accuracy of classifying limited and advanced FL from Medicare claims data (accuracy: ≤64%; sensitivity: ≤72%; specificity: ≤57%). Conclusions: Higher frequencies of specialist physician visits and living in counties with no HPSA can reduce the risk of presenting with advanced FL. Patients with stages II-IV incur significantly higher costs compared to stage I patients. The incremental cost increases with higher FL stage. Predicting advanced FL from claims data may not be feasible and researchers may need to rely on datasets with existing clinical information.
    • Effect of Transient Heat Exposure on Drug Delivery from Transdermal and Topical Products

      Thomas, Sherin; Stinchcomb, Audra L. (2020)
      Heating pads and electric blankets are widely used for relief from pain and to provide warmth, respectively. Their unintentional application simultaneously with a transdermal or topical system can result in unexpected drug levels in systemic circulation. Designing well-characterized in vitro and in vivo methods are vital to understanding the effect of heat and hence can aid in the development and evaluation of these products. The objective of this work was to evaluate the effect of heat on products with the same active pharmaceutical ingredient (API) but different inactive ingredients. Four drug molecules with different physicochemical properties were chosen. For each drug, formulations with different excipients were selected. In vivo serum drug profile and in vitro flux profile data can provide mechanistic understanding of heat effect on these formulations. Four topical diclofenac formulations were evaluated for heat effect in vitro under continuous heat exposure. Their flux profiles demonstrated the influence of formulation design and excipients on drug permeation at elevated skin temperature. Serum profiles of two different oxybutynin formulations evaluated under heat exposure showed very different magnitude of enhancement in serum levels under similar heat exposure conditions. Another objective of this work was establishing an in vitro - in vivo correlation (IVIVC) of heat effect on topical and transdermal formulations. This will help in characterizing and predicting heat effect minimizing the need of clinical trials and support the regulatory evaluation of these dosage forms. For buprenorphine patch, study design for in vitro permeation testing (IVPT) using human skin was well characterized to align with and mimic in vivo conditions of heat exposure. Level A and Level C IVIVC were established under normal as well as elevated temperature conditions. For lidocaine patches, IVIVC was observed for early heat effect. However, poor correlation was observed for late heat effect. The findings from this work determined IVPT studies can correlate with and be predictive of in vivo results under normal temperature conditions. But under suboptimal conditions like heat exposure, IVPT may have limitations and should be used in addition to other methods to evaluate heat effect.
    • Evaluation of the Equivalency of Generic Drugs

      Das, Sharmila; Polli, James E. (2020)
      The objective of this dissertation is to assess the bioequivalence of generic drugs. Patients with epilepsy complain about more seizures and side effects after brand-generic or generic-generic switching of an anti-epileptic drug (AED). Generic brittleness (GB) is the familiar notion that, upon switching between AEDs of pharmaceutical equivalents, a patient experiences negative outcome. Aim 1 is to probe the individual patient attributes thought to predispose a patient to generic brittleness. At the University of Maryland Medical Center, 148 patients from the outpatient epilepsy clinic were recruited for an observational case-control study. An algorithm for being GB (40% of patients) and not GB was devised. A patient with epilepsy was categorized as GB if the patient negatively opined about generics and was taking brand of their most problematic AED when generic was available. Two demographic factors that increased the odds of being GB were a patient currently taking a problem AED and increasing total number of current medications. Interestingly, taking lamotrigine increased and taking any one of six “protective” anti-epileptic drugs decreased the odds of being GB, respectively. Furthermore, no genetic, clinical laboratory or neuropsychiatry tests or their sub-elements differentiated GB patients from not GB patients. Aim 2 involves a comparative pharmacokinetic (PK) analysis upon challenging sixteen GB patients to brand-generic or generic-generic switch of an AED that they are currently on, using a four-way crossover replicate design. For each patient, test and reference PK profiles were the same, despite patients being GB. Aim 3 is to assess the noninferiority of the generic sodium ferric gluconate (SFG) against the reference product Ferrlecit with respect to drug bound iron (DBI), after single dose intravenous administration of brand and generic SFG in 44 healthy volunteers. Using a two-way crossover replicate design, plasma PK profiles of SFG to Ferrlecit were the same across two iron species (e.g. DBI and NTBI), although adverse event rates differed. In conclusion generics of AEDs and intravenous sodium ferric gluconate are bioequivalent to the brand-name drugs. Results support FDA criteria for bioequivalence in regards to AEDs and complex iron products.
    • From Data to Decisions: Utilizing Pharmacometrics to Optimize Clinical Therapeutics and Drug Development in Neuropsychiatry

      Kalaria, Shamir; Gopalakrishnan, Mathangi (2020)
      At least 50% of clinical trials of neuropsychiatric compounds fail due to an unclear understanding of disease pathophysiology and drug pharmacology. Further, lack of dosing information in special patient populations for approved neuropsychiatric drugs could contribute to suboptimal outcomes. The current research highlights the role of pharmacometrics in (i) optimizing therapeutics in patients receiving antiepileptics and continuous renal replacement therapy (CRRT) and (ii) informing efficient trial design for binge eating disorder (BED). Currently, no dosing recommendations exist for CRRT patients receiving antiepileptics. Real-world clinical studies were conducted to characterize the pharmacokinetics of levetiracetam and lacosamide in patients (N=18) receiving CRRT at the University of Maryland Medical Center. Major determinants for drug clearance were drug-specific extraction coefficient (EC) approximated to fraction unbound (levetiracetam: 0.89, lacosamide: 0.80), effluent flow rate, and preserved non-renal clearance. Ex-vivo models of CRRT were developed using human plasma and normal saline containing albumin solutions. The developed ex-vivo in-vivo correlation model demonstrated an average bias of <15% in predicting in-vivo CRRT clearance for levetiracetam and lacosamide. Similarity in ECs justified the ability to bridge dosing information across CRRT modalities. This research, in combination with a priori knowledge of drug pharmacokinetics, confirms the use of ex-vivo CRRT models to establish dosing recommendations and alleviate the need for CRRT pharmacokinetic studies. The development of BED therapies are challenged by high placebo response and high dropout rates in clinical trials. A comprehensive disease-drug-trial (DDT) model was developed using data from 12 different investigator-led BED clinical trials (N = 578; 6 to 16-week duration) to inform optimal clinical trial design elements. Baseline BED severity metrics were predictors for placebo response and dropouts. Stimulants and anticonvulsants demonstrated 1.8 times higher effect differences as compared to antidepressants. Among the clinical trial designs (placebo run-in, drug run-in, sequential parallel comparison design) evaluated in-silico, placebo-controlled trial of shorter (6-week) duration with model-based analysis demonstrated superior trial design properties (40% lower sample size with 50% lower dropouts) as compared to current 12-week registration trials for BED. The proposed DDT framework can inform efficient trial design and potentially increase the number of therapeutic options for BED.
    • Pharmacometric Approaches to Precision Therapeutic Management for Antimicrobials

      Wang, Hechuan; Ivaturi, Vijay (2020)
      Antimicrobials have been widely used for decades in the treatment of various types of bacterial infections and their properties have been thoroughly characterized in pediatric and adult patients. However, high variability and unpredictability of antimicrobials’ pharmacokinetics (PK) in patients still exist, which reinforces the value of precision dosing. The research in this thesis highlights the role of pharmacometrics in precision therapeutic management of two prototype antimicrobials, gentamicin and rifampin. The first project developed a Bayesian forecasting algorithm for precision dosing of gentamicin in pediatrics. We developed the first population PK model for gentamicin across the whole pediatric age spectrum ranging from 1-day-old newborns to 19-year-old young adults. The model utilized physiologically plausible covariate parameterization driven by principles of allometric scaling. Renal function changes manifested by glomerular filtration were described by postmenstrual age, and serum creatinine was standardized by age. The model was used as a prior in the subsequent full Bayesian analyses in pediatric patients. A full Bayesian analysis-based model-informed precision dosing (MIPD) was introduced for gentamicin dosing in pediatric patients. With a predefined probability of target attainment (PTA) criteria of 70% for both maximum and trough concentrations, the dosing regimens recommended by the empirical dosing guideline NeoFax could achieve the predefined criteria in about 5% of the 1013 patients, in comparison with 90% of the patients when the initial dosing recommendation from the MIPD approach was used. Finally, a workflow was designed for a new patient in a clinical scenario to provide MIPD for initial dosing recommendation and dosing adjustment after TDM level becomes available via a full Bayesian approach. The second project focuses on dose optimization of rifampin in adult patients with tuberculosis through dynamic positron emission tomography (PET) scans. A semi-mechanistic PK-lung-biodistribution model was developed based on plasma and intralesional drug concentration data measured by PET scans. The model could well predict the mass spectrometry data from therapeutic dose and PET data from 11C-labled micro-dose. The developed model was externally validated through exposure predictions in the therapeutic range of 10-35 mg/kg. Based on the projected drug exposure in the cavity walls at higher rifampin doses, the bacterial killing curves obtained from hollow fiber systems were used to predict the clinical cure rates in humans for higher rifampin doses (>600mg). Standard oral rifampin dosing of 10 mg/kg would achieve a 95% probability of cure in 6-9 months of treatment. Similarly, an oral rifampin dose of at least 35 mg/kg would be needed to cure patients in 4 months.
    • Evaluation of skin tape stripping in healthy human volunteers as a methodology for quantifying local drug bioavailability from dermal products

      Shukla, Sagar; Stinchcomb, Audra L.; Hassan, Hazem (2020)
      Stratum corneum (SC) tape stripping is a valuable methodology that has been used for quantifying bioavailability (BA) of topical drug products at the site of action. Although the Food and Drug Administration (FDA) tape stripping guidance was withdrawn several years ago due to variable results, with an appropriate study design, tape stripping procedures can be a reproducible BA method. Therefore, the objective of this work was to investigate the use of tape stripping to quantify BA and evaluate in vitro/in vivo correlations (IVIVC) of two model compounds (lidocaine and diclofenac). These compounds were selected for their differing physicochemical properties and skin permeation rates. Two healthy human volunteer pharmacokinetic and tape stripping studies were conducted to quantify the BA in the SC and measure the elimination rate constant through the skin (kesc). Investigator variability from the in vivo tape stripping study was also examined, and the method variability potentially induced by the investigator can be mitigated by the quality by design (QBD) approach of using transepidermal water loss (TEWL) for determining when most of the SC has been removed in each individual volunteer. TEWL readings assisted the investigator by representing the SC tape stripping endpoint, and the SC masses removed from each volunteer were similar for the two investigators. Harmonized IVPT studies were also conducted and key parameter estimates were determined (absolute bioavailability (F) and (kesc)). These parameter estimates were used to simulate in vivo SC drug concentrations. The error in the SC drug concentration predictions from both in vivo studies was usually less than 20% compared to observed values, which demonstrates the predictive power of carefully harmonized IVPT studies. IVPT studies require less time and expense than human studies, and therefore these models play an important role in the early stages of drug development to predict in vivo SC drug concentrations, and absorption of drug through the skin. In this study, in vivo kesc for a quickly permeating drug (lidocaine) appears to be well predicted by IVPT; however, further work needs to be done to predict a slowly permeating drug’s (diclofenac) SC drug concentrations and kesc.
    • Therapeutic Effect of Anti-Progranulin/GP88 Antibody AG01 in Triple Negative and Letrozole Resistant ER+ Breast Cancer Cells

      Guha, Rupa; Serrero, Ginette (2020)
      Progranulin (GP88, PCDGF, granulin/epithelin precursor, acrogranin) is a secreted autocrine growth/survival glycoprotein that functions as a biological driver of tumor cell proliferation, tumorigenesis, survival, invasiveness and drug resistance in several cancers, including breast cancer. Progranulin is found in the serum of breast cancer patients at higher levels than in healthy subjects and pathological studies have shown that in ER+ tumor biopsies, progranulin/GP88 is an independent prognostic factor of recurrence. Although TNBC represents a small percentage (15-20%) of breast cancer diagnoses, it is clinically important because of its highly aggressive nature and the fact that the disease progresses to metastasis within an exceedingly shorter period. Higher progranulin levels have also been shown to be associated with TNBC cases. Progranulin represents a therapeutic and diagnostic target in breast cancer. We have characterized a recombinant neutralizing anti-human progranulin/GP88 monoclonal antibody AG01 that inhibits progranulin biological effect in vitro and in vivo. Since GP88 is associated with poor outcomes in BC patients, we have investigated the effect of AG01 to inhibit proliferation and enhance letrozole responsiveness of letrozole resistance breast cancer cell lines as well as inhibit proliferation and migration of TNBC cells, two breast cancer areas with unmet medical needs for targeted therapy. We found that progranulin levels were sharply elevated in letrozole resistant cells as compared to the parent cell lines. Simultaneously, TNBC cells showed an increase in progranulin expression while it is undetectable in normal mammary cells. This emphasized the importance of targeting PGRN to treat letrozole resistance in ACLRTUSM as well as provide a therapeutic agent in TNBC cells. We report here that treatment of ACLRTUSM with anti-PGRN antibody (AG01) not only reduced their proliferation but increased the sensitivity of ACLRTUSM cells towards letrozole treatment. In several TNBC models, AG01 treatment reduced cell proliferation, migration, and invasion. Taken together, the research work discussed here provides new information to better understand the targeting progranulin and the effectiveness of AG01 as a potential therapeutic agent in breast cancer. Future work continuing characterization of AG01 will provide further insight into its role in regulating cancer biology.
    • Impact of the Medicare Annual Wellness Visit on Geographic Variation in Dementia Diagnosis

      Hanna, Maya; Perfetto, Eleanor M. (2020)
      Background: Alzheimer's-disease-and-related-dementia (ADRD) is often misdiagnosed or diagnosis is late in disease progression. Diagnosis variations can be driven by access variations related to geographic location. To improve timely and accurate ADRD diagnosis, the Medicare Annual Wellness Visit (AWV) required a cognitive assessment, starting in 2011, which may reduce diagnosis variations. Objective: Assess impact of the AWV on geographic variation in ADRD diagnosis and outcomes. Methods: Aim 1: ADRD patients and caregivers from western, central, and eastern Maryland were interviewed to understand diagnosis-pathway geographic differences. Data were analyzed using interpretative phenomenological analysis to identify themes. Aim 2: Using the CMS Chronic Condition Data Warehouse (CCW) and HRSA Area Health Resource Files, 5-year, county-level ADRD cumulative incidence were compared pre- (2006-2010) and post- (2011-2015) AWV implementation in Mid-Atlantic states. Geographically-weighted, generalized linear models assessed the association between the AWV and ADRD cumulative incidence, controlling for demographic and access measures. Aim 3: A retrospective cohort study using CCW was conducted in newly diagnosed ADRD individuals. Health care utilization (HCU) was compared for individuals with an AWV pre-diagnosis versus no AWV. Difference-in-difference models assessed 10-month outcomes between exposure groups. Results: Aim 1: Average time from first doctor visit (concerning signs/symptoms) to ADRD diagnosis was 3.3, 2, and 5.3 years for western, central, and eastern regions, respectively. Aim 2: AWV participation was not significantly associated with increased 5-year ADRD cumulative incidence. The association between AWV and 5-year ADRD cumulative incidence varied by county with stronger associations clustered in eastern Virginia, Maryland, and Delaware. Aim 3: Receiving an AWV pre-diagnosis was associated with increased HCU [ED (rate ratio [RR]: 1.20, 95% confidence interval [CI]: 1.11, 1.30), hospitalizations (RR: 1.26, 95% CI: 1.13, 1.40), and outpatient (RR: 1.08, 95% CI: 1.04, 1.12)]. Conclusions: Longer times to ADRD diagnosis were observed in rural versus urban regions. The AWV demonstrates the potential to minimize geographic differences by increasing diagnosis rates and HCU. Due to low and variable participation during early implementation, the true impact of the AWV is yet to be established. It may take longer to see impacts on longer-term outcomes.
    • Effects of Static Growth on P. aeruginosa Iron Homeostasis and Virulence

      Brewer, Luke; Oglesby, Amanda G.; Kane, Maureen A. (2020)
      Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogens that causes life-threatening, antimicrobial resistant infections in vulnerable patient populations, including patients with cystic fibrosis, cancer, and chronic wounds. During infection, P. aeruginosa requires iron to maintain critical aspects of its metabolism, and possesses numerous virulence factors and iron uptake mechanisms that allow it to compete for this essential metallo-nutrient in the iron-limiting host environment. These systems are tightly regulated by iron-responsive regulatory mechanisms, which ensure adequate uptake while preventing iron toxicity. Because of the essential role of these regulatory mechanisms in maintaining iron homeostasis, they are considered a promising approach for treating P. aeruginosa infections. One prominent regulator of P. aeruginosa iron homeostasis is the PrrF small RNA (sRNA) regulator, which is essential for virulence in acute murine lung infection. Unfortunately, the exact contribution of PrrF to P. aeruginosa pathogenesis has not yet been elucidated. Moreover, our current understanding of PrrF and other iron regulatory mechanisms is largely based on studies using shaking and highly aerated cultures, which are not likely representative of microbial communities in vivo. To address these gaps, the work in this thesis utilizes proteomic, metabolic, and genetic approaches to determine the impact of static growth on iron-responsive regulatory mechanisms in P. aeruginosa, including PrrF sRNAs. We demonstrate that iron regulation paradigms in P. aeruginosa are dramatically altered in static conditions, due in part to changes in PrrF activity. Notably, we identify type 6 secretion systems (T6SS) as a target of enhanced iron regulation in P. aeruginosa in static conditions, and demonstrate that this altered regulation is caused by changes in the production and activity of the PrrF-regulated quorum signaling molecules, 2-alkyl-4(1H)-quinolones (AQs). Furthermore, we demonstrate that altered AQ activity may modulate clinically-significant interactions with other opportunistic pathogens, such as S. aureus, In turn, the work described herein has broad implications for the study of P. aeruginosa infections, and highlights the need to further probe essential P. aeruginosa iron homeostasis mechanisms in static conditions.
    • Metabolism-based Alterations of Constitutive Androstane Receptor (CAR) Activity and Downstream Effects

      Mackowiak, Bryan; Wang, Hongbing, Ph.D. (2019)
      The xenobiotic defense network in the liver has evolved so that many foreign compounds can activate xenobiotic receptors like the constitutive androstane receptor (CAR) and the pregnane x receptor (PXR), induce the expression of drug metabolizing enzymes, and enhance the clearance of drugs. Typically, autoinduction of a compound’s metabolism leads to its breakdown, disrupting the detoxification feedback loop. However, multiple lines of evidence suggest that metabolites of autoinducers can have diverse effects on xenobiotic receptors, including agonism and antagonism conversion, and cause unexpected consequences, including drug-drug interactions (DDIs) that can lead to liver toxicity. While the effect of xenobiotic receptor-mediated CYP induction on drug metabolism has been well-characterized, the effect of metabolism on the activity of xenobiotic receptors has received little attention. Although the “traditional” role of CAR revolves around inducing xenobiotic metabolism and detoxification, evidence has accumulated that CAR also plays important roles in energy metabolism, cellular proliferation, and liver homeostasis, making it a potential drug target for various liver disorders. In addition, the effects of CAR activation in human primary hepatocytes (HPH) are not well understood and need further study to determine whether or not CAR is a potential drug target for different types of liver dysfunction, including cancer. The overall objectives of this proposal are to investigate the effect of drug metabolism on CAR activity, identify FDA-approved drugs and metabolites that alter CAR activity, and determine whether CAR activation is beneficial for liver disorders such as cancer. Using CAR as a model xenobiotic receptor, my studies have shown that potent CAR antagonist PK11195 is metabolized to a CAR agonist in metabolically-competent systems. Therefore, I hypothesize that hepatic metabolism capacity and CAR activity can form a regulatory feedback loop, altering the PK/PD profiles of drug substrates. Successful completion of these studies has provided a model for metabolism-based changes in xenobiotic receptor activity, identified FDA-approved drugs that modulate CAR activity, and determined the clinically-relevant downstream effects of CAR activation.
    • Itraconazole-HPMCAS amorphous spray dried dispersions: composition and process factors impacting performance

      Honick, Moshe Avraham; Polli, James E. (2019)
      Despite their potential for improving the oral bioavailability of poorly water soluble drugs, spray dried dispersions (SDDs) have properties that make them challenging to formulate. The objective of this dissertation was to elucidate composition and process factors for favorable SDD performance and to develop fast-, medium-, and slow-release formulations for an IVIVC study. Itraconazole (ITZ) was used as a model poorly soluble drug and hypromellose acetate succinate (HPMCAS) was used as a carrier polymer for the SDDs. Film casting proved to be a useful screening method for demonstrating the feasibility of producing amorphous SDDs of ITZ and HPMCAS as well as for rank ordering the grades of HPMCAS (i.e. HPMCAS-L > HPMCAS-M > HPMCAS-H) in terms of in-vitro dissolution performance. Producing solid oral dosage forms of ITZ-HPMCAS SDDs proved challenging due to the low particle size, poor flowability, and low bulk density of the SDDs. Initial tableting on a Natoli hand-operated press showed that drug release from tablets containing SDDs of ITZ and HPMCAS-L were very sensitive to small differences in compaction pressure and porosity. Interestingly, the same sensitivity was not observed in SDDs of ITZ and HPMCAS-M. Using a compaction simulator, reproducible fast-, medium- and slow-release tablet formulations of ITZ and HPMCAS SDDs was developed by varying polymer grade (HPMCAS-L, HPMCAS-M), slugging pressure (20, 40 MPa), and compaction pressure (70, 85, 100 MPa). The performance of SDDs was further evaluated by comparing the compaction behavior of ITZ-HPMCAS SDDs and physical mixtures of ITZ and HPMCAS. Although the compressibility of both the SDDs and physical mixtures were similar, the SDDs had a greater tendency to laminate, especially at higher compression speeds. Tablets of SDDs containing ITZ and HPMCAS-L were particularly prone to lamination compared to the SDDs containing HPMCAS-M or HPMCAS-H. Interestingly, when the SDDs were not laminated they had a greater tensile strength than tablets produced with the physical mixtures. In conclusion, there are significant challenges associated with formulating SDDs of ITZ and HPMCAS. In addition to elucidating composition and process factors impacting performance, fast-, medium-, and slow-release formulations for an IVIVC study were developed.
    • The Design and Development of Dual MCL-1/BCL-2 and HDM2/Bcl-2 Protein Family Inhibitors Using a Polypharmacology Approach

      Drennen, Brandon; Fletcher, Steven (2019)
      Apoptosis, a cellular process that leads to cell death, is a vital signaling pathway for maintaining homeostasis. Intracellular-activated apoptosis is regulated by the B-cell lymphoma 2 (BCL-2) family of proteins, which encompasses two classes of proteins: the pro-apoptotic and anti-apoptotic members. Apoptosis is controlled by a protein-protein interaction (PPI) between the two members. Specifically, the anti-apoptotic proteins’ surface hydrophobic binding groove binds to the α-helical Bcl-2 homology 3 (BH3) domain of the pro-apoptotic proteins, thus inhibiting apoptosis. During apoptotic conditions, BH3 activator proteins are expressed and disrupt the PPI, initiating apoptosis. During tumorigenesis, the anti-apoptotic proteins are overexpressed and capture the activator proteins before they can act, progressing tumor development. A strategy developed to overcome this oncogenic transformation is BH3 mimicry, the design of small molecules that behave like BH3 activators to free the pro-apoptotic proteins. Though potent BH3 mimetics have been synthesized, cytotoxic and resistance issues have arisen. Specifically, BCL-XL inhibition causes thrombocytopenia within patients and BCL-2 inhibition causes resistance mechanisms to emerge that involve the upregulation of MCL-1. Presently, there are no potent dual inhibitors of BCL-2 and MCL-1 to overcome these issues. Additionally, p53 has been shown to regulate apoptosis through the Bcl-2 family by either direct interactions or increasing their expression. P53 is rapidly degraded due to the overexpression of HDM2, a ubiquitin ligase, within cancer cells. The PPI between p53 and HDM2 resembles the PPI between the members of the Bcl-2 family. Also, Venetoclax (BCL-2 inhibitor) and idasanutlin (HDM2 inhibitor) act synergistically in combination therapies. Thus, we followed a polypharmacology approach to synthesize dual BCL-2/MCL-1 and dual HDM2/Bcl-2 family inhibitors. We were able to create potent dual MCL-1/BCL-2 indazole inhibitors (Ki MCL-1 < 1.50 µM, BCL-2 < 0.050 µM, BCL-XL > 10.00 µM), dual HDM2/Bcl-2 family pyrazole and imidazole inhibitors (Ki MCL-1 < 0.050 µM, HDM2 < 25.00 µM), HSQC-confirmed nicotinate-based MCL-1 inhibitors (Ki MCL-1 < 3.00 µM) and a new alpha-helix mimetic scaffold for disrupting PPIs. Further optimization of these inhibitors is planned, along with cell viability studies. Overall, these inhibitors can serve as starting points for future experiments and polypharmacology designs.
    • Novel Cholinergics for Treatment of Central Nervous System Disorders

      Johnson, Chad; Coop, Andrew; 0000-0001-7584-3000 (2019)
      Approximately 16% of Americans are diagnosed with major depressive disorder, a mental disorder thought be caused by a combination of characterized by genetic, biological, environmental, and psychological factors. It can be accompanied by low self-esteem, loss of interest in normally enjoyable activities, low energy, and diminished quality of life. Between 2-7% of adults with this disorder die by suicide. In addition, almost half of patients who are treated initially with an SSRI do not achieve complete remission, and nearly a third after four different treatment regimens (nimh.nih.gov). While counseling and antidepressant medication can be effective treatments, current selective serotonin re-uptake inhibitors (SSRI's) take weeks before therapeutic effects are observed. This "delay" period of action is not well understood and presents a significant challenge for medical professionals in the management of major depression. Mechanisms of anti-depressants have been a major focus of both current/past research in hopes of developing more effective and faster acting drugs. Directly related to this, clinical data (nimh.nih.gov) that oral and intravenous treatment with the muscarinic cholinergic antagonist scopolamine had rapid anti-depressant effects in humans--likely mediated through an antimuscarinic effect. Unfortunately, scopolamine can produce cognitive impairment including memory disturbances due to its anticholinergic properties. Since major depressive disorder is associated with deficits in cognition, this would produce an undesired additive effect that would only exacerbate the problem. It is our goal to identify a muscarinic antagonist that may be able to relieve depression and have little to no effect on memory or cognition. The 3-exo-1-azabicyclo[2.2.1]heptane, 1-azabicyclo[2.2.2]octane, 1-azabicyclo[3.2.1]octane, and N-methyltetrahydropyidine 3 (and 4)-substituted-1,2,4-oxadiazoles appear to be excellent chemical scaffolds for the generation of potent muscarinic agonists/antagonists. In order to probe the orthosteric site of the mAChRs we designed a large library of compounds and evaluated them via a battery of pharmacological assays to confirm both their antidepressant and cognitive effects. This resulted in the identification of lead compound (CJ2100) that showed potent antidepressant activity without cognitive impairment. (Supported by NIMH Grant 107499)
    • Advancing Drug and Biomaterial Design with Constant pH Molecular Dynamics Simulations

      Tsai, Cheng-chieh; Shen, Jana (2019)
      Molecular dynamics (MD) simulation is a valuable tool for investigating motions of macromolecular systems; however, solution pH, a critical factor for biological and chemical processes, is neglected in conventional MD simulations. To address this weakness, our group developed various continuous constant pH molecular dynamic (CpHMD) tools. In this dissertation, applications and new protocols that utilize CpHMD for drug and biomaterial design are presented. β-secretase 1 (BACE1, implicated in Alzheimers disease) and Src kinase (implicated in cancer) were utilized as model systems for drug design applications. In chapter 2, we applied CpHMD to understand the binding of BACE1 with two small-molecular inhibitors. We discovered that, despite the structural similarity of the two inhibitors, the titration behavior of the protein active site differs and this difference dramatically impacts the protein-ligand interactions and consequently the inhibitor affinity. Further, we tested a new protocol that combines CpHMD titration with free energy simulations to construct the pH-dependent binding free energy profiles. The resulting data showed excellent agreement with experiment and identified one potential allosteric site in BACE1. Next, in chapter 3, we simulated Src kinase to test the capability of CpHMD tostudy kinases. Starting from the crystal structure of the inactive Src, CpHMD can capture the conformational activation along the major inactive states without introducing any biasing potential or mutation. Starting from chapter 4, we studied the chitosan-based hydrogel systems to explore the detailed molecular mechanisms that give rise to macroscopic materials properties. We examined the flexibility of chitosan chains under different environmental conditions such as pH and salt concentration. Simulation data revealed that in addition to electrostatic screening, salt ions enhance the chain flexibility by interrupting the intra-molecular hydrogen bonds and thereby shifting the conformational populations between extended and bent states. In chapter 5, the atomic-level mechanism of pH-responsive chitosan-based hydrogels with switchable mechanical properties was investigated. Our data suggested that the electrostatic crosslinks are formed through the pH-dependent salt-bridge interactions between the chitosan glucosamines and surfactant headgroups. The pKa difference between the chitosan crystallite and the surfactant-bound chitosan is a key for the persistent but erasable gradient in the structural and mechanical properties between the two crosslinked regions. In summary, my work provids insights that will contribute to drug and biomaterial design and highlights the usefulness of CpHMD in these fields.
    • Developing a patient-driven cost-effectiveness analysis of pharmacological treatments for patients with chronic hepatitis C

      Mattingly II, T. Joseph; Mullins, C. Daniel; 0000-0001-7786-5780 (2019)
      Background: Innovations in hepatitis C virus (HCV) drug therapy included in comparative clinical effectiveness evaluations focus on sustained virologic response (SVR) without consideration of socioeconomic or psychological outcomes. This study aimed to identify and prioritize variables important to patients and determine the impact of patient-centered parameters on the cost effectiveness of HCV treatments. Methods: An individual-based state-transition model was developed with the guidance of a patient-centered multi-stakeholder advisory board and patient-only Delphi panel. The model was used to perform a patient-driven cost-effectiveness analysis (CEA) of direct acting antivirals (DAAs) over 10 and 20 year time horizons from both health sector and societal perspectives. The patient-centered model and CEA results were then compared with recently published HCV CEAs. Results: Patients identified treatment effectiveness, longer life, fear of complications, financial issues, quality of life, and impact on society as important factors to include. Fear of harming others was considered more important than physical symptoms in terms of patient-reported problems caused by HCV. Total infected life-years (ILYs) and work days missed were reduced in the treatment group for both 10 and 20 year health sector models in addition to quality-adjusted life-year gains. Compared to no treatment, the incremental cost-effectiveness ratio for treatment would be $3,464/ILYs avoided, $715/work day missed, and $39,086/QALY gained. When costs of absenteeism, presenteeism, and patient/caregiver time were included, the DAA intervention was cost-saving at both 10 and 20 years. Very few traditional economic models for HCV treatments attempt to capture the indirect and non-medical costs or outcomes that may impact HCV patients. Conclusions: Treatment was cost-effective from a health sector perspective and cost-saving when including non-health costs such as patient/caregiver time and productivity. Compared to published HCV CEAs that focused mainly on SVR, our patient-centered CEA provides results that reflect the outcomes of interest informed by direct patient engagement.
    • Application of Machine Learning Algorithms for Predicting Missing Cost Data

      Rueda, Juan-David; Slejko, Julia; 0000-0002-0907-7106 (2019)
      Objective: To compare new alternatives to estimate health care costs in the presence of missing data using methods based on machine-learning (ML). Introduction: Costs must be correctly estimated for value assessment and budget calculations. Problems arise when they are not correctly estimated. Sometimes costs can be biased and lead to wrong decisions that affect population health. Cost estimation is a challenging task and it is more challenging in the presence of missing data. Methods: We used Surveillance, Epidemiology, and End Results program (SEER)-Medicare including patients with multiple myeloma newly diagnosed from 2007-2013. We explored the problem of missing data using different approaches creating artificial missing data. We hypothesized that the use of ML techniques improves the prediction of mean medical total costs in the presence of missingness. ML methods included support vector machines, boosting, random forest, and classification and regression trees. First, we analyzed the problem considering only one dimension, when one variable is missing in a cross-sectional scenario, using generalized linear models as a comparator against ML. Then, we added time as a factor for missingness, utilizing reweighted estimators against ML. Finally, we explored the different levels of censoring and determined how each censoring level affected our cost estimations. In this case, we created multiple linear spline models to establish the effect of censoring on the bias of the estimator. Results: We demonstrated that ML algorithms had better prediction when data were missing completely at random and missing at random. All the methods performed badly in the missing not at random scenario. In the second aim, we showed that ML-based methods predict just as well as reweighted estimators for the five-year total cost of a patient with multiple myeloma. Lastly, we found that ML methods are consistent and robust at low and moderate levels of censoring; however, we failed to prove that they are better than the reweighted estimators. Conclusions: ML-based methods are a good alternative for the prediction of missing cost data in the case of cross-sectional and longitudinal data.
    • Effect of Cadmium Exposure on the Transport System of Organic Cation Transporters and Multidrug and Toxin Extrusion Proteins (OCTs/MATEs)

      Yang, Hong; Shu, Yan, Ph.D. (2019)
      The universal pollution by cadmium (Cd) in our agricultural land and the prevalence of cigarette smoking make the environmental Cd exposure an unneglectable human health concern. While the mechanism of cadmium accumulation has been extensively studied, no explicit mechanism has been reported regarding the elimination of cadmium from the body. On the other hand, whereas Cd exposure has been correlated with a variety of diseases, little is known pertaining to its effect on drug disposition and response in patients. Thus, we aim to delineate the mechanism of cadmium elimination and detoxification and to gain new insights into its effect on xenobiotic disposition and response. The OCTs/MATEs transport system are pair of transporter proteins highly expressed at the basolateral and apical membrane of hepatocytes and renal proximal tubules respectively. Recently, Cd has been identified as a substrate of OCTs, while we determined that MATEs could reduce the toxicity of Cd by serving as its efflux transporters in vitro. In addition, knockout of Mate1 in mice kidney resulted in higher renal toxicity in both chronic and acute Cd intoxication studies. We found that Cd was an inducer of OCT activity while an inhibitor towards MATEs in cells. Consistently, Cd exposure could lead to accumulation of the substrates of these transporters in mouse liver and kidney. Being focused on human (h) OCT2 and MATE1, our mechanistic studies revealed that hOCT2, as compared to hMATE1, was more active in trafficking between the plasma membrane and the cytoplasmic storage pool. Cd exposure could trigger the formation of a protein complex consisting of AKT2, calmodulin and AS160, which could then selectively facilitate the phosphorylation of AKT2 at T309, and initiate the translocation of hOCT2 to the plasma membrane. Altogether, our findings have identified MATE transporters as new contributors for Cd detoxification, and provided foundation to uncover environmental Cd as a previously unrecognized factor for the broad variation in drug disposition and response.
    • Medical Costs of Alpha-1 Antitrypsin Deficiency-associated Chronic Obstructive Pulmonary Disease in the United States

      Sieluk, Jan; Mullins, C. Daniel; 0000-0002-1833-0273 (2018)
      Objectives: The objective of this study was to isolate the healthcare resource utilization and economic burden attributable to the presence of a genetic factor among Chronic Obstructive Pulmonary Disease (COPD) patients with and without Alpha-1 Antitrypsin Deficiency (AATD), twelve months before and after their initial COPD diagnosis. Methods: Retrospective analysis of OptumLabs® Data Warehouse claims (OLDW; 2000 – 2017). The OLDW is a comprehensive, longitudinal real-world data asset with de-identified lives across claims and clinical information. AATD-associated COPD cases were matched with up to 10 unique non-AATD-associated COPD controls. Healthcare resource use and costs were assigned into the following categories: office (OV), outpatient (OP), and emergency room visits (ER), inpatients stays (IP), prescription drugs (RX), and other services (OTH). A generalized linear model was used to estimate total pre- and post-index (initial COPD diagnosis) costs from a third-party payer’s perspective (2018 USD) controlling for age, gender, race/ethnicity, census region, augmentation therapy use, oxygen use, insurance type, year of COPD diagnosis, and Charlson Comorbidity Score. Healthcare resource utilization was estimated using a negative binomial regression. Results: The study population consisted of 8,881 patients (953 cases matched with 7,928 controls). The AATD-associated COPD cohort had higher expenditures and use of OV and OTH services, as well as OV, OP, ER, RX, and OTH before and after the index date, respectively. Adjusted total cost ratios for AATD-associated COPD patients as compared to controls were 2.036 [95% CI: 1.601 – 2.590] and 1.976 [95% CI: 1.550 – 2.517] while the incremental cost difference totaled $6,861 [95% CI: $3,025 - $10,698] an $5,772 [95% CI: $1,940 - $9,604] per patient before and after the index date, respectively. Conclusions: Twelve months before and after their initial COPD diagnosis, patients with AATD incur higher healthcare utilization costs that are double the cost of similar patients without AATD. This study also suggests that increased costs of AATD-associated COPD are not solely attributable to augmentation therapy use. Future studies should further explore the relationship between augmentation therapy, healthcare resource use, and other AATD-associated COPD expenditures.