Maximizing retention in long-term clinical trials of a weight loss agent: use of a dietitian support team.

OBJECTIVE: High-attrition rates have been observed in long-term clinical trials of weight loss agents. We evaluated the impact of an innovative retention programme on 1-year retention. METHODS: Three Phase 3 global multicentre clinical trials evaluated the efficacy and safety of a CB1 receptor antagonist in subjects with BMI ≥ or = 27 kg/m2. The impact of a multifaceted retention programme including a dietitian screening interview, a comprehensive culturally adapted lifestyle modification programme, and a dietitian support system to maximize lifestyle adherence, was evaluated in 4,410 subjects from four subpopulations (non-US English-speaking, non-English-speaking, US-without dietitian screening and US-with dietitian screening) comprising 208 centres from 15 countries. RESULTS: The median proportion retained over the first year among subjects in three protocols was 82%. Non-English-speaking countries showed higher retention rates (89%) compared with the USA (73%) and non-US English-speaking (81%) countries. Within the USA, behavioural screening was associated with 29% reduction in dropout rate; for every five monthly teleconferences attended above 11, there was a 32% decrease in dropout rate. CONCLUSIONS: This novel retention programme greatly improved upon reported retention rates of studies conducted with other weight loss agents in long-term clinical trials. Its effectiveness should be confirmed in future trials.

Mixed-effects modelling to quantify the effect of empagliflozin on renal glucose reabsorption in patients with type 2 diabetes.

AIMS: To quantify the effect of the sodium-glucose co-transporter 2 inhibitor, empagliflozin, on renal glucose reabsorption in patients with type 2 diabetes, and to evaluate covariate effects, using a mechanistic population pharmacokinetic-pharmacodynamic (PK-PD) model. METHODS: Four phase I/II trials were used for model development. Empagliflozin's PK characteristics were characterized by a two-compartmental model with sequential zero- and first-order absorption. Urinary glucose excretion (UGE) was described as dependent on renal glucose filtration and reabsorption; splay of the glucose reabsorption/excretion curves was considered. The modelling assumed that empagliflozin lowers the maximum renal glucose reabsorption capacity and, thereby, the renal threshold for glucose (RTg). Covariate effects were investigated using a full covariate modelling approach, emphasizing parameter estimation. RESULTS: The PK-PD model provided a reasonable description of the PK characteristics of empagliflozin and its effects on UGE across a range of renal function levels. Its parameters are consistent with reported values for renal physiology. Using this model, the effect of empagliflozin on renal glucose reabsorption was quantified. Steady-state empagliflozin doses (1, 5, 10 and 25 mg) reduced RTg from 12.5 mmol/L [95% confidence interval (CI) 12.0, 13.1] to 5.66 (95% CI 4.62, 6.72), 3.01 (95% CI 2.33, 3.69), 2.53 (95% CI 1.83, 3.14) and 2.21 (95% CI 1.47, 2.84) mg/dl, respectively. Covariate analysis showed the effect of empagliflozin on UGE was not influenced, to a clinically relevant extent, by sex, age or race. CONCLUSIONS: A method for characterizing renal glucose reabsorption was developed that does not require complex glucose clamp experiments. These analyses indicate that empagliflozin provided concentration-dependent RTg reductions, with 10 and 25 mg providing near-maximum RTg-lowering.

Connecting the Dots: Linking Osteocyte Activity and Therapeutic Modulation of Sclerostin by Extending a Multiscale Systems Model.

The goal of this work was to extend a mathematical, multiscale systems model of bone function, remodeling, and health in order to explore hypotheses related to therapeutic modulation of sclerostin and quantitatively describe purported osteocyte activity within bone remodeling events. A pharmacokinetic model with first-order absorption and dual elimination pathways was used to describe the kinetics of romosozumab, a monoclonal antibody (mAb) against sclerostin. To describe total circulating sclerostin, an extended indirect response model of inhibition of offset was developed. These models were subsequently linked to the systems model, with sclerostin signaling changes in resorption and formation through established osteocyte-mediated mechanisms. The model proposes relative contributions of the osteocyte to the RANKL pool, a major player in feedback signaling, and is used to explore hypotheses surrounding attenuation of anabolic activity after multiple doses of sclerostin mAbs, a phenomenon whose mechanism is poorly understood.

FDA Advisory Meeting Clinical Pharmacology Review Utilizes a Quantitative Systems Pharmacology (QSP) Model: A Watershed Moment?

In the evolving discipline of quantitative systems pharmacology (QSP), QSP model (QSPM) applications are expanding. Recently, a QSPM was used by US Food and Drug Administration (FDA) clinical pharmacologists to evaluate the appropriateness of a proposed dosing regimen for a new biologic. This application expands the use-horizon for QSPMs into the regulatory domain. Here we retrace the evolution of the model and suggest a question-based approach to directing model scope, identifying applications, and understanding overall QSPM value.

Two dose-ranging studies with PF-04937319, a systemic partial activator of glucokinase, as add-on therapy to metformin in adults with type 2 diabetes.

AIM: To assess the efficacy and safety of a range of doses of a systemic, partial, glucokinase activator, PF-04937319, as add-on therapy to metformin, in patients with type 2 diabetes mellitus (T2DM). METHODS: Patients were randomized to once-daily PF-04937319 doses of 10, 50, 100 mg, or matching placebo (Study B1621002); or PF-04937319 doses of 3, 20, 50, 100 mg, or matching placebo (Study B1621007). Titrated glimepiride (Study B1621002) or sitagliptin (Study B1621007) were included in a double-dummy manner. The primary measure was change from baseline in glycated haemoglobin (HbA1c) at week 12. Key secondary measures included other glycaemic variables and safety and tolerability. RESULTS: In the 639 patients randomized, the minimally efficacious PF-04937319 dose was identified as 50 mg once daily. At the highest PF-04937319 dose tested (100 mg), on average, a clinically significant reduction in HbA1c [-4.94 or -5.11 mmol/mol (-0.45 or -0.47%), placebo-adjusted], which was similar to that achieved with sitagliptin [-4.69 mmol/mol (-0.43%)] but lower than that achieved with titrated glimepiride [-9.07 mmol/mol (-0.83%)], was observed. At this dose, the effect on fasting plasma glucose was not consistent between the two studies (Study B1621002 vs Study B1621007: placebo-adjusted mean change of -0.83 vs +0.50 mmol/l). PF-04937319 was well tolerated at doses up to 100 mg. Hypoglycaemia was reported in 2.5% of patients (on placebo), 5.1% of patients (on PF-04937319 100 mg), 1.8% of patients (on sitagliptin) and 34.4% of patients (on titrated glimepiride). CONCLUSIONS: In patients on metformin monotherapy, the addition of a 100-mg dose of PF-04937319 improved glycaemic control and was well tolerated.

Multicenter validation of urinary CXCL9 as a risk-stratifying biomarker for kidney transplant injury.

Noninvasive biomarkers are needed to assess immune risk and ultimately guide therapeutic decision-making following kidney transplantation. A requisite step toward these goals is validation of markers that diagnose and/or predict relevant transplant endpoints. The Clinical Trials in Organ Transplantation-01 protocol is a multicenter observational study of biomarkers in 280 adult and pediatric first kidney transplant recipients. We compared and validated urinary mRNAs and proteins as biomarkers to diagnose biopsy-proven acute rejection (AR) and stratify patients into groups based on risk for developing AR or progressive renal dysfunction. Among markers tested for diagnosing AR, urinary CXCL9 mRNA (odds ratio [OR] 2.77, positive predictive value [PPV] 61.5%, negative predictive value [NPV] 83%) and CXCL9 protein (OR 3.40, PPV 67.6%, NPV 92%) were the most robust. Low urinary CXCL9 protein in 6-month posttransplant urines obtained from stable allograft recipients classified individuals least likely to develop future AR or a decrement in estimated glomerular filtration rate between 6 and 24 months (92.5-99.3% NPV). Our results support using urinary CXCL9 for clinical decision-making following kidney transplantation. In the context of acute dysfunction, low values can rule out infectious/immunological causes of injury. Absent urinary CXCL9 at 6 months posttransplant defines a subgroup at low risk for incipient immune injury.

Mitochondrial gene replacement in human pluripotent stem cell-derived neural progenitors.

Human pluripotent stem cell-derived neural progenitor (hNP) cells are an excellent resource for understanding early neural development and neurodegenerative disorders. Given that many neurodegenerative disorders can be correlated with defects in the mitochondrial genome, optimal utilization of hNP cells requires an ability to manipulate and monitor changes in the mitochondria. Here, we describe a novel approach that uses recombinant human mitochondrial transcription factor A (rhTFAM) protein to transfect and express a pathogenic mitochondrial genome (mtDNA) carrying the G11778A mutation associated with Leber's hereditary optic neuropathy (LHON) disease, into dideoxycytidine (ddC)-treated hNPs. Treatment with ddC reduced endogenous mtDNA and gene expression, without loss of hNP phenotypic markers. Entry of G11778A mtDNA complexed with the rhTFAM was observed in mitochondria of ddC-hNPs. Expression of the pathogenic RNA was confirmed by restriction enzyme analysis of the SfaN1-digested cDNA. On the basis of the expression of neuron-specific class III beta-tubulin, neuronal differentiation occurred. Our results show for the first time that pathogenic mtDNA can be introduced and expressed into hNPs without loss of phenotype or neuronal differentiation potential. This mitochondrial gene replacement technology allows for creation of in vitro stem cell-based models useful for understanding neuronal development and treatment of neurodegenerative disorders.

Predicting nonlinear changes in bone mineral density over time using a multiscale systems pharmacology model.

A mathematical model component that extends an existing physiologically based multiscale systems pharmacology model (MSPM) of calcium and bone homeostasis was developed, enabling prediction of nonlinear changes in lumbar spine bone mineral density (LSBMD). Data for denosumab, a monoclonal antibody osteoporosis treatment, dosed at several levels and regimens, was used for fitting the BMD component. Bone marker and LSBMD data extracted from the literature described on/off-treatment effects of denosumab over 48 months [Miller, P.D. et al. Effect of denosumab on bone density and turnover in postmenopausal women with low bone mass after long-term continued, discontinued, and restarting of therapy: a randomized blinded phase 2 clinical trial. Bone 43, 222-229 (2008)]. An indirect model linking bone markers to LSBMD was embedded in the existing MSPM, reasonably predicting nonlinear increases in LSBMD during treatment (24 months); LSBMD declines following discontinuation and increases upon treatment reinstitution. This study demonstrates the utility of MSPM extension to describe a phenomena of interest not originally in a model, and the ability of this updated MSPM to predict nonlinear longitudinal changes in the clinically relevant endpoint, LSBMD, with denosumab treatment.CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e14; doi:10.1038/psp.2012.15; advance online publication 14 November 2012.

Integrated pharmacometrics and systems pharmacology model-based analyses to guide GnRH receptor modulator development for management of endometriosis.

Endometriosis is a gynecological condition resulting from proliferation of endometrial-like tissue outside the endometrial cavity. Estrogen suppression therapies, mediated through gonadotropin-releasing hormone (GnRH) modulation, decrease endometriotic implants and diminish associated pain albeit at the expense of bone mineral density (BMD) loss. Our goal was to provide model-based guidance for GnRH-modulating clinical programs intended for endometriosis management. This included developing an estrogen suppression target expected to provide symptomatic relief with minimal BMD loss and to evaluate end points and study durations supportive of efficient development decisions. An existing multiscale model of calcium and bone was adapted to include systematic estrogen pharmacologic effects to describe estrogen concentration-related effects on BMD. A logistic regression fit to patient-level data from three clinical GnRH agonist (nafarelin) studies described the relationship of estrogen with endometrial-related pain. Targeting estradiol between 20 and 40 pg/ml was predicted to provide efficacious endometrial pain response while minimizing BMD effects.CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e11; doi:10.1038/psp.2012.10; advance online publication 17 October 2012.

Rate of reformation of tongue coatings in young adults.

BACKGROUND: Reviewing the literature, no study on the rate of regrowth of tongue coatings after tongue cleaning was found. Therefore, the purpose of this study in young adults was to study the rate of reformation of tongue coatings after mechanical removal. MATERIAL AND METHODS: Thirty-five dental students participated in the present study. Following preparatory study instructions, baseline examinations were carried out followed by 3 days of observation. At baseline, tongue coating scores (prescraping) were obtained followed by tongue scrapings and determination of the wet weights of the coatings. A second tongue coating score was then obtained within 5 min of the first score (immediate post-scraping). The subjects returned for repeated tongue coating scores after 1 and 2 days and for final examination after 3 days, which included both tongue coating scores (prescraping and immediate post-scraping) and determination of the wet weights of the coatings. RESULTS: Prior to scraping the tongue at day 0 (baseline), mean tongue coating amounted to a surface extension of 33% of the entire dorsum of the tongue. Scraping the tongue reduced the score to 9%. On average, tongue coating scores had returned to baseline levels on day 2. The mean wet weights of tongue scrapings at days 0 and 3 were similar and amounted to 0.09 +/- 0.07 and 0.09 +/- 0.06 g, respectively. CONCLUSION: If tongue cleaning is to be recommended, the results of this study in dental students indicate that tongue cleaning should be performed on a daily basis.

Long-term outcome for lymph node-positive prostate cancer.

Although the number of men with lymph node-positive prostate cancer has declined, it is still significant and the challenge remains on how best to treat these patients. Only long-term follow-up can give a true indication of the outcome in prostate cancer. We evaluated our experience in treating lymph node-positive prostate cancer with a median follow-up of 10.2 years. The overall 5-year survival was 78% and the 10-year survival was 56%. Length of tumor control depends on the type of treatment given. Adding androgen ablation improves the duration of control dramatically, although optimal timing is still uncertain.

High-resolution ROMA CGH and FISH analysis of aneuploid and diploid breast tumors.

Combining representational oligonucleotide microarray analysis (ROMA) of tumor DNA with fluorescence in situ hybridization (FISH) of individual tumor cells provides the opportunity to detect and validate a wide range of amplifications, deletions, and rearrangements directly in frozen tumor samples. We have used these combined techniques to examine 101 aneuploid and diploid breast tumors for which long-term follow-up and detailed clinical information were available. We have determined that ROMA provides accurate and sensitive detection of duplications, amplifications, and deletions and yields defined boundaries for these events with a resolution of <50 kbp in most cases. We find that diploid tumors exhibit fewer rearrangements on average than aneuploids, but rearrangements occur at the same locations in both types. Diploid tumors reflect at least three consistent patterns of rearrangement. The reproducibility and frequency of these events, especially in very early stage tumors, provide insight into the earliest chromosomal events in breast cancer. We have also identified correlations between certain sets of rearrangement events and clinically relevant parameters such as long-term survival. These correlations may enable novel prognostic indicators for breast and other cancers as more samples are analyzed.

Long-term follow-up of radiotherapy for prostate cancer.

PURPOSE: To determine the long-term outcome of radiotherapy for prostate cancer. METHODS AND MATERIALS: A total of 136 consecutive patients with prostate cancer underwent primary radiotherapy. All but 4 patients received 6000 cGy to the prostate. The minimal follow-up was 22.9 years. RESULTS: Of the 136 patients, 93 had Stage B (T2), 9 Stage A (T1), and 34 Stage C (T3). Sixty-nine percent of the patients developed recurrence, and 51% of all patients died of prostate cancer. The recurrences developed at a steady state throughout the length of follow-up. One half the recurrences occurred after 10 years, and recurrence was still observed >20 years after treatment. The survival rate at 5, 10, 15, 20, and 25 years was 81%, 59%, 37%, 16%, and 10%, respectively. The recurrence-free survival rate at 25 years was 17%. The median survival for Grade 3-4 patients was 6.3 years and for Grade 1-2 patients was 13.0 years. The median survival for those with T1 tumors was 12.9 years; T2 tumors, 12.4 years; and T3 tumors, 9.5 years. CONCLUSION: Despite favorable early results, with long-term follow-up, patients continued to experience prostate cancer recurrence. Unless they died an intercurrent death, they were highly likely to develop recurrence and die of prostate cancer. The conclusions from treatment studies with <15 years of follow-up should be viewed as preliminary.

Long-term follow-up of radical retropubic prostatectomy for prostate cancer.

OBJECTIVES: The ultimate outcome of patients after radical prostatectomy is often predicted from statistical projections of short-term follow-up. Only actual long-term follow-up can demonstrate true outcome. METHODS: One hundred thirty-one patients underwent retropubic prostatectomy for clinically organ confined prostate cancer and have been followed for a minimum of 22.5 years. Preoperatively, all but 12 had clinically palpable cancer. RESULTS: Overall survival in these patients was similar to an age-matched population, with 65% alive at 15 years, and 23% alive at 25 years. Thirty-seven percent of the patients recurred and 24% of all the patients died of prostate cancer. For patients with pathologically organ confined disease, 27% recurred, while those with extension outside the gland or positive nodes had an 83% recurrence rate. Although, the median time to recurrence was 7 years, recurrences occurred at a steady-state throughout the length of follow-up. Patients with higher grade tumors, even if organ confined, were significantly more likely to recur. CONCLUSIONS: In a cohort of patients treated with radical prostatectomy for predominantly palpable disease, long-term follow-up (79% deceased) reveals that 37% will recur and 24% will die of prostate cancer. Almost half the recurrences occurred after 10 years, indicating that reports with shorter follow-up will underestimate the recurrence rate.

Frozen section diagnosis of metastatic prostate adenocarcinoma in pelvic lymphadenectomy compared with nomogram prediction of metastasis.

OBJECTIVES: To compare the sensitivity and negative predictive values of frozen section analysis of pelvic lymphadenectomy in patients undergoing radical retropubic prostatectomy for prostate adenocarcinoma with the predictive power of published nomograms for metastasis to lymph nodes. METHODS: A retrospective review was performed on all patients who underwent bilateral pelvic lymphadenectomy and radical retropubic prostatectomy for prostate adenocarcinoma between 1991 and early 1997. The sensitivity and negative predictive values were computed comparing frozen section analysis, and patients were grouped by risk stratification. Comparison was made using the McNemar text. RESULTS: The sensitivity for detecting lymph node metastasis on frozen section analysis for all risk groups was 33% (9 of 27). The sensitivity for identifying patients at high risk of having nodal metastasis by published nomograms alone was 67% (18 of 27) (P = 0.04). The overall negative predictive value for frozen section analysis was 96.5% (503 of 521). The negative predictive value for uninvolved lymph nodes, using low and intermediate-risk groups stratified by published nomograms, was 97.9% (436 of 445). CONCLUSIONS: Frozen section analysis of pelvic lymph nodes to detect metastatic prostate adenocarcinoma is less sensitive in determining which patients will have lymph nodes involved by metastatic adenocarcinoma than using risk stratification by published nomograms. The negative predictive value of frozen section analysis in all risk groups was very high, up to 97.9%.

A computerized reminder strategy is effective for annual influenza immunization of children with asthma or reactive airway disease.

BACKGROUND: Influenza virus infection frequently triggers asthma exacerbation and hospitalization. Annual influenza immunization is recommended for children with chronic conditions, including those with asthma or reactive airway disease (RAD); however, <10% receive it each year. METHODS: In September, 1997, we instituted a computerized staged reminder strategy for annual influenza immunization of children with asthma/RAD at the Scott and White Pediatric Clinic in Temple. A reminder letter, followed six weeks later by an autodial recall telephone message, was sent to the parent/guardian of children with asthma/RAD using the Shared Medical Systems to identify children with asthma/RAD and the Integrated Client Encounter System to record immunizations. The effect of this computerized reminder system on the influenza immunization rate of a cohort of 925 Scott and White Pediatric Clinic children with asthma/RAD was examined for the 1996 to 1997 and 1997 to 1998 influenza seasons, before and after intervention. RESULTS: A significant increase in influenza immunization rate from 5.4% to 32.1% occurred in all age groups, regardless of the insurance status. The medically attended acute respiratory illness rate per 100 subjects was significantly higher in vaccinated than in unvaccinated children for each of the two influenza epidemics and in the period between the two epidemics. CONCLUSION: A computerized reminder letter followed by an autodial recall telephone message is effective in increasing the influenza immunization rate of children with asthma/RAD. Children with significantly higher respiratory morbidity during and in between two influenza epidemics were more likely to be immunized after receiving written and telephone autodial reminders.

Red blood cell transfusion practices in very low birth weight infants in 1990s postsurfactant era.

The purposes of this study are (1) to evaluate the practice of red blood cell transfusions in very low birth weight (VLBW) infants (between 501 to 1500 g) during the postsurfactant era of the 1990s; and (2) to evaluate if there is a decreasing trend in red cell transfusions in the 1990s. Database and medical records of VLBW infants admitted to the neonatal intensive care unit (NICU) between January 1990 and December 1995 at Scott & White Clinic, Temple, Texas, were reviewed. Five hundred twenty-seven infants were admitted to the NICU, excluding 5 infants that were transferred out for possible cardiac surgery or for other reasons. Fifty one (9.7%) of these infants died prior to discharge. Hence, data from 476 survivors were reviewed for red blood cell (RBC) transfusions. Transfusions were given at the discretion of the attending neonatologist. None of the infants received erythropoietin. Of the 476 infants, 289 (61%) received RBC transfusions during the hospital stay, with 2.7+/-3.6 transfusions per infant with a volume of 40.5+/-50.4 mL/kg. Smaller infants required significantly more transfusions compared to larger infants when divided into 250-g subgroups. No statistically significant difference was noted in the number of RBC transfusions per infant or number of infants transfused during the 6-year period from year to year. We conclude that VLBW infants in the 1990s postsurfactant era required 2.7 RBC transfusions per infant, on average, with the smallest infants requiring the most transfusions. These data will be helpful to counsel mothers in preterm labor regarding the need of transfusions for each birth weight category. Red cell transfusion practice has not changed over this 6-year period in the 1990s. Additional measures such as erythropoietin or even stricter transfusion criteria may be necessary to decrease transfusions further. However, safety of such measures should be carefully evaluated.

Psychometric properties of the Observer Alexithymia Scale in a clinical sample.

The purpose of this study was to evaluate the psychometric properties of the Observer Alexithymia Scale (OAS; Haviland, Warren, & Riggs, 2000) in a clinical setting. Clinical and counseling psychologists used the OAS to rate outpatients (n = 192) with various Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994) diagnoses. Reliability and validity data are similar to the initial nonclinical data (n = 819): OAS scores are reliable (coefficient alpha = .90), and the five-factor structure--Distant, Uninsightful, Somatizing, Humorless, and Rigid--was confirmed. Moreover, the OAS does a relatively good job of differentiating clinical from nonclinical cases. The OAS is psychometrically sound, and it appears to be a useful tool for collecting and evaluating observer data on the clinically relevant, everyday expressions of alexithymia.

Characterization of an intestinal epithelial cell receptor recognized by the Cryptosporidium parvum sporozoite ligand CSL.

The protozoan parasite Cryptosporidium parvum is a leading cause of diarrhea in humans and neonatal calves. The absence of approved parasite-specific drugs, vaccines, and immunotherapies for cryptosporidiosis relates in part to limited knowledge on the pathogenesis of zoite attachment and invasion. We recently reported that the C. parvum apical complex glycoprotein CSL contains a zoite ligand for intestinal epithelial cells which is defined by monoclonal antibody (MAb) 3E2. In the present study, the host cell receptor for CSL was characterized. For these studies, a panel of epithelial and mesenchymal cell lines was examined for permissiveness to C. parvum and the ability to bind CSL. Cells of epithelial origin were significantly more permissive and bound significantly greater quantities of CSL than cells of mesenchymal origin. Caco-2 intestinal cells were selected from the epithelial panel for further characterization of the CSL receptor. Immunoelectron microscopy demonstrated that CSL bound initially to the surface of Caco-2 cells and was rapidly internalized. The molecule bound by CSL was identified as an 85-kDa Caco-2 cell surface protein by radioimmunoprecipitation and CSL affinity chromatography. Sporozoite incubation with the isolated 85-kDa protein reduced binding of MAb 3E2. Further, attachment and invasion were significantly inhibited when sporozoites were incubated with the 85-kDa protein prior to inoculation onto Caco-2 cells. These observations indicate that the 85-kDa protein functions as a Caco-2 cell receptor for CSL. CSL also bound specifically to intestinal epithelium from calves, indicating receptor expression in a second important host species. Molecular characterization of the CSL receptor may lead to novel avenues for disrupting ligand-receptor interactions in the pathogenesis of C. parvum infection.