Clinical and Economic Outcomes of Erythropoiesis-Stimulating Agent Hyporesponsiveness in the Post-Bundling Era

Rationale & Objective

Since the change in erythropoiesis-stimulating agent (ESA) labeling and bundling of dialysis services in the United States, few studies have addressed the clinical importance of ESA hyporesponsiveness and none have considered health care resource use in this population. We aimed to further explore ESA hyporesponsiveness and its consequences.

Study Design

Retrospective observational cohort study.

Setting & Participants

US Renal Data System Medicare participants receiving dialysis with a minimum 6 months of continuous ESA use from 2012 to 2014.

Predictors

Erythropoietin resistance index (≥2.0 U/kg/wk/g/L) and ESA dose were used to identify ESA hyporesponders and hyporesponsive subgroups: isolated, intermittent, and chronic.

Outcomes

Associations between ESA responsiveness and mortality, cardiovascular hospitalization rates, and health care resource use were evaluated and compared across subgroups.

Analytical Approach

Baseline characteristics were compared using Wilcoxon rank sum tests for continuous variables and χ² tests for categorical variables. Incidence rates of health care resource use were modeled using an unadjusted and adjusted generalized linear model.

Results

Of 834,115 dialysis patients in the CROWNWeb database, 38,891 ESA hyporesponders and 59,412 normoresponders met all inclusion criteria. Compared with normoresponders, hyporesponders were younger women, weighed less, and had longer durations of dialysis (all P < 0.001). Hyporesponders received 3.8-fold higher ESA doses (mean, 94,831 U/mo) and erythropoietin resistance index was almost 5 times higher than in normoresponders. Hyporesponders had lower hemoglobin levels and parathyroid hormone levels > 800 pg/mL, and iron deficiency was present in 26.5% versus 10.9% in normoresponders. One-year mortality was higher among hypo- compared with normoresponders (25.3% vs 22.6%). Hyporesponders also had significantly higher rates of hospitalization for cardiovascular events, emergency department visits, inpatient stays, home health agency visits, skilled nursing facility, and hospice days.

Limitations

Only US Medicare patients were included and different hyporesponder definitions may have influenced the results.

Conclusions

This study explored ESA hyporesponsiveness using new definitions and incorporated clinical and economic outcomes. It established that ESA-hyporesponsive dialysis patients had higher mortality, cardiovascular hospitalization rates, and health care costs as compared with ESA-normoresponsive patients.

Elicitation of disease concepts in patients with diabetic foot ulcers: a qualitative study

OBJECTIVE

To identify in-depth information directly from patients with diabetic foot ulcers (DFU) on DFU symptoms, impacts on functioning and effects on health-related quality of life (HRQoL).

METHOD

Semi-structured, qualitative concept elicitation interviews were conducted with patients with DFUs (Wagner grade 1 or 2) until saturation was reached. Qualitative analysis (using MAXQDA, VERBI GmbH, Germany) of interview transcripts was conducted to identify concepts relevant to patients with DFUs, based on the frequency of mentions, and elucidate themes regarding impacts on HRQoL.

RESULTS

Of the 18 participants, most were male (n=14; 78%) and 10 (56%) presented with a Wagner grade of 1. Frequently reported symptoms were pain/discomfort (n=15; 83%), weeping/discharge (n=10; 56%), bleeding (n=10; 56%) and swelling (n=8; 44%). Overall, patients reported more impacts than symptoms-wound care/treatment burden (n=14; 78%), limitations on exercise/physical activity (n=13; 72%), mobility limitations (n=12; 67%), and offloading (n=12; 67%) were the most frequently mentioned. Based on findings from the patient interviews, a draft conceptual model was developed outlining interrelationships between DFU symptoms, impacts, and HRQoL from the patient perspective.

CONCLUSION

Qualitative interviews captured the breadth of disease-related concepts of direct importance to patients. The draft conceptual model developed from the analysis can help identify measures or instruments for use in assessing patient-reported symptoms or HRQoL in clinical practice and may have wider research applicability, including evaluation of treatment benefits in patients with DFUs.

Discovery of Pyrazolocarboxamides as Potent and Selective Receptor Interacting Protein 2 (RIP2) Kinase Inhibitors

Herein we report the discovery of pyrazolocarboxamides as novel, potent, and kinase selective inhibitors of receptor interacting protein 2 kinase (RIP2). Fragment based screening and design principles led to the identification of the inhibitor series, and X-ray crystallography was used to inform key structural changes. Through key substitutions about the N1 and C5 N positions on the pyrazole ring significant kinase selectivity and potency were achieved. Bridged bicyclic pyrazolocarboxamide 11 represents a selective and potent inhibitor of RIP2 and will allow for a more detailed investigation of RIP2 inhibition as a therapeutic target for autoinflammatory disorders.

Application of the Stable Isotope Label Approach in Clinical Development-Supporting Dissolution Specifications for a Commercial Tablet Product with Tafenoquine, a Long Half-life Compound

Bioavailability/bioequivalence studies supporting clinical drug development or commercial supply of drug formulations are often time, cost, and resource intensive. The drug's pharmacokinetic (PK) variability, systemic half-life, and safety issues may pose additional challenges. The stable isotope label (SIL) approach provides a useful tool to significantly reduce the study size in clinical PK studies. Tafenoquine (TQ) is an 8-aminoquinoline under development for preventing Plasmodium vivax malaria relapse. This SIL study assessed the impact of differences in the in vitro dissolution profiles on in vivo exposure of TQ tablets. Fourteen healthy volunteers received a single dose of 300 mg TQ Intermediate Aged or 300 mg TQ Control formulations in this single-center, two-arm, randomized, open-label, parallel-group study. Endpoints included the geometric means ratio of the area under the concentration-time curve (AUC_(0-t) and AUC_(0-∞); primary endpoint) and maximum plasma concentration (C_max) for Intermediate Aged versus Control TQ; correlation of PK parameters for venous versus peripheral (via microsample) blood samples; and safety and tolerability endpoints. Geometric mean ratios for PK parameters (AUC and C_max) and their 90% confidence intervals fell well within standard bioequivalence limits (0.80-1.25). Only one mild adverse event (skin abrasion) was reported. In summary, this SIL methodology-based study demonstrates that the observed differences in the in vitro dissolution profiles between the Control and Intermediate Aged TQ tablets have no clinically relevant effect on systemic TQ exposure. The SIL approach was successfully implemented to enable the setting of a clinically relevant dissolution specification.

CLINICAL TRIAL

This study (GSK study number 201780) is registered at clinicaltrials.gov with identifier NCT02751294.

Crystal structures of human RIP2 kinase catalytic domain complexed with ATP-competitive inhibitors: Foundations for understanding inhibitor selectivity

Receptor interacting protein 2 (RIP2) is an intracellular kinase and key signaling partner for the pattern recognition receptors NOD1 and NOD2 (nucleotide-binding oligomerization domain-containing proteins 1 and 2). As such, RIP2 represents an attractive target to probe the role of these pathways in disease. In an effort to design potent and selective inhibitors of RIP2 we established a crystallographic system and determined the structure of the RIP2 kinase domain in an apo form and also in complex with multiple inhibitors including AMP-PCP (β,γ-Methyleneadenosine 5'-triphosphate, a non-hydrolysable adenosine triphosphate mimic) and structurally diverse ATP competitive chemotypes identified via a high-throughput screening campaign. These structures represent the first set of diverse RIP2-inhibitor co-crystal structures and demonstrate that the protein possesses the ability to adopt multiple DFG-in as well as DFG-out and C-helix out conformations. These structures reveal key protein-inhibitor structural insights and serve as the foundation for establishing a robust structure-based drug design effort to identify both potent and highly selective inhibitors of RIP2 kinase.

Use of novel small molecule inhibitors to investigate the role of endogenous RIP2 kinase activity in modulating NOD2/RIP2-dependent cytokine signaling (172.4)

RIP2 is a Ser/Thr protein kinase, which undergoes autophosphorylation and activates NF-κB and MAPKs following stimulation of the upstream NOD1/NOD2 receptors resulting in proinflammatory cytokine production. Previous studies using transient overexpression systems have suggested that RIP2 kinase activity mediates NOD1/2-dependent signaling by regulating cellular RIP2 protein levels. To interrogate whether this is also the case for endogenous RIP2 kinase, we used novel, potent and highly-selective small-molecule RIP2 kinase inhibitors to study MDP-stimulated signaling in both primary human monocytes and human colonic epithelial (HCT116) cells. We demonstrated that inhibition of RIP2 kinase activity blocks proinflammatory cytokine production in monocytes in the absence of detectable changes in total RIP2 protein levels. Using TNFα-primed HCT116 cells, we confirmed these observations and demonstrated a direct correlation between the inhibition of endogenous RIP2 kinase activity (measured as a decrease in pS176-RIPK2 levels) and a reduction in proinflammatory cytokine signaling in response to MDP-stimulation. Our data confirm the importance of endogenous RIP2 kinase activity in modulating proinflammatory cytokine release from both human monocytes and intestinal epithelial cells in response to bacterial ligands. Furthermore, our results suggest that RIP2 kinase inhibition may represent a novel therapeutic strategy for the treatment of intestinal inflammation.

Height and weight charts for Mexican adults

The relation between height and weight is one of the criteria most widely used by doctors to evaluate nutritional condition. The simplest way to establish this relationship is to consult a chart that indicates what a person's weight should be in relation to his height. The charts for adults used in Mexico are deficient, since their design was based on popluations from other countries. In this study the advantages and limitations of this method for evaluating nutritional condition are pointed out and charts designed with data on Mexican university students are presented and compared with the charts that are most frequently being used in Mexico now.