Anemia management practice patterns in small dialysis organizations following implementation of the prospective payment system.

BACKGROUND: The impact of the United States Prospective Payment System (PPS) "bundle payment system" on anemia management within small dialysis organizations (SDOs) was studied to evaluate the financia burden on SDOs. METHODS: Facilities enrolled in the original study on SDOs were grouped into three hemoglobin (Hb) categories by subject-months: > 25% of subjectmonths with Hb < 10 g/dL (sub-10); > 25% of subject-months with Hb > 12 g/dL (super-12); remaining facilities (10 - 12 group). Subjectlevel data aggregated to facility level for Hb concentration, intravenous (IV) epoetin ± (EA) dose per administration, dose titration, and EA administration frequency during the baseline and follow-up periods were described. RESULTS: Baseline demographic characteristics were imbalanced between the sub-10 (n = 7) and super-12 facilities (n = 5). Mean (SD) Hb concentrations were similar for sub-10 (11.1 (3.0) g/dL) and super-12 (11.6 (2.2) g/dL) facilities during the baseline period, but differed during the follow-up period (10.4 (2.7) vs. 11.4 (2.3) g/dL). The median (Q1, Q3) EA IV dose per administration during follow-up was 3,726 (3,467, 3,961) and 5,712 (4,816, 7,324) units in the sub-10 and super-12 facilities, respectively. A small trend toward upward titration was seen. CONCLUSIONS: Results suggest a difference in anemia management between sub-10 and super-12 facilities during the first year of PPS implementation. Future analyses evaluating patterns of reimbursement and shifts in clinical practice guidelines are warranted globally.

Dynamics of cinacalcet use and biochemical control in hemodialysis patients: a retrospective New-user cohort design.

BACKGROUND: Cinacalcet is used to treat secondary hyperparathyroidism among hemodialysis patients. Large-scale epidemiologic studies describing patterns of cinacalcet use, effects on parathyroid hormone (PTH), calcium, and phosphorous levels, and predictors of discontinuation have not been previously reported. METHODS: This retrospective cohort study used a clinical database of a large U.S. dialysis provider (2007-2010) merged with administrative data from the United States Renal Data System. Among new users of cinacalcet with Medicare coverage, trends in PTH, calcium, and phosphorus were measured in 30-day intervals following cinacalcet initiation. RESULTS: Seventeen thousand seven hundred sixty-three eligible initiators contributed 111,047 30-day follow-up intervals. Of these, 56 % discontinued cinacalcet by month 4. Of those discontinuing, 76.3 % reinitiated. Mean values of PTH, calcium, and phosphorus decreased to recommended levels within 4 months following initiation. Proximal PTH levels < 150 pg/mL were associated with discontinuation: HR = 1.23 (95 % CI: 1.12, 1.36), whereas low calcium (< 7.5 mg/dL) was suggestive of an association, HR = 1.09 (95 % CI 0.91, 1.32). Being in the Part D gap period increased discontinuation risk: HR = 1.09 (95 % CI: 1.03, 1.16). Low-income subsidy status decreased discontinuation risk: HR = 0.77 (95 % CI 0.69, 0.86). Predictors of reinitiation included low-income subsidy, HR = 1.32 (95 % CI 1.22, 1.43); higher albumin level, HR = 1.23 (95 % CI 1.10, 1.36) and higher calcium level, HR = 1.26 (95 % CI 1.19, 1.33). CONCLUSIONS: Substantial and expected declines in laboratory values occurred following cinacalcet initiation. Early discontinuation and reinitiation of cinacalcet were common and may have occurred for clinical and economic reasons.

Risk of pure red cell aplasia in patients with hepatitis C receiving antiviral therapy and an erythropoiesis-stimulating agent.

Antibody-mediated pure red cell aplasia (PRCA) has been primarily observed in patients with chronic kidney disease treated with an erythropoiesis-stimulating agent (ESA); only a few anecdotal cases have been reported in other patient populations. We searched the Amgen Global Safety Adverse Event Database and identified 14 patients with hepatitis C who developed severe anemia, anti-erythropoietin antibodies, and bone marrow biopsy-proven PRCA, while receiving interferon therapy (with or without ribavirin) and an ESA. During the follow-up period and after ESA treatment stopped, 11 patients no longer required transfusions and 3 did. Analysis of antibody isotypes showed that, contrary to reports of patients with chronic kidney disease, immunoglobulin G1 was the predominant isotype rather than immunoglobulin G4 (immunoglobulin G4 was detected in only 1 of 6 patients). Epitope mapping showed the anti-erythropoietin antibodies bound domains required for receptor binding. Therefore, the potential benefits of ESA therapy must be weighed against the risk for PRCA in patients with hepatitis C who are receiving treatment with interferon and ribavirin.

Early trends from the Study to Evaluate the Prospective Payment System Impact on Small Dialysis Organizations (STEPPS).

BACKGROUND: Launched in January 2011, the prospective payment system (PPS) for the US Medicare End-Stage Renal Disease Program bundled payment for services previously reimbursed independently. Small dialysis organizations may be particularly susceptible to the financial implications of the PPS. The ongoing Study to Evaluate the Prospective Payment System Impact on Small Dialysis Organizations (STEPPS) was designed to describe trends in care and outcomes over the period of PPS implementation. This report details early results between October 2010 and June 2011. STUDY DESIGN: Prospective observational cohort study of patients from a sample of 51 small dialysis organizations. SETTING & PARTICIPANTS: 1,873 adult hemodialysis and peritoneal dialysis patients. OUTCOMES: Secular trends in processes of care, anemia, metabolic bone disease management, and red blood cell transfusions. MEASUREMENTS: Facility-level data are collected quarterly. Patient characteristics were collected at enrollment and scheduled intervals thereafter. Clinical outcomes are collected on an ongoing basis. RESULTS: Over time, no significant changes were observed in patient to staff ratios. There was a temporal trend toward greater use of peritoneal dialysis (from 2.4% to 3.6%; P = 0.09). Use of cinacalcet, phosphate binders, and oral vitamin D increased; intravenous (IV) vitamin D use decreased (P for trend for all <0.001). Parathyroid hormone levels increased (from 273 to 324 pg/dL; P < 0.001). Erythropoiesis-stimulating agent doses decreased (P < 0.001 for IV epoetin alfa and IV darbepoetin alfa), particularly high doses. Mean hemoglobin levels decreased (P < 0.001), the percentage of patients with hemoglobin levels <10 g/dL increased (from 12.7% to 16.8%), and transfusion rates increased (from 14.3 to 19.6/100 person-years; P = 0.1). Changes in anemia management were more pronounced for African American patients. LIMITATIONS: Limited data were available for the prebundle period. Secular trends may be subject to the ecologic fallacy and are not causal in nature. CONCLUSIONS: In the period after PPS implementation, IV vitamin D use decreased, use of oral therapies for metabolic bone disease increased, erythropoiesis-stimulating agent use and hemoglobin levels decreased, and transfusion rates increased numerically.

A Phase I First-in-Human Study of ABBV-383, a B-Cell Maturation Antigen × CD3 Bispecific T-Cell Redirecting Antibody, in Patients With Relapsed/Refractory Multiple Myeloma.

PURPOSE: ABBV-383, a B-cell maturation antigen × CD3 T-cell engaging bispecific antibody, has demonstrated promising results in an ongoing first-in-human phase I study (ClinicalTrials.gov identifier: NCT03933735) in patients with relapsed/refractory multiple myeloma (RRMM). Herein, we report safety and efficacy outcomes of this phase I dose escalation/expansion study. METHODS: Patients with RRMM (≥ three prior lines including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 monoclonal antibody) were eligible. ABBV-383 was administered intravenously over 1-2 hours once every 3 weeks, without any step dosing. A 3 + 3 design with backfilling for dose escalation was used (intrapatient escalation to highest safe dose permitted) followed by initiation of dose expansion. RESULTS: As of January 8, 2022, 124 patients (dose escalation [0.025-120 mg], n = 73; dose expansion [60 mg], n = 51) have received ABBV-383; median age was 68 years (range, 35-92 years). The most common hematologic treatment-emergent adverse events (TEAEs) were neutropenia (all grades: 37%) and anemia (29%). The most common nonhematologic TEAEs were cytokine release syndrome (57%) and fatigue (30%). Seven deaths from TEAEs were reported with all considered unrelated to study drug by the investigator. For all efficacy-evaluable patients (n = 122; all doses), the objective response rate (ORR) was 57% and very good partial response (VGPR) or better (≥ VGPR) rate was 43%. In the 60 mg dose expansion cohort (n = 49), the ORR and ≥ VGPR rates were 59% and 39%, respectively; and in the ≥ 40 mg dose escalation plus dose expansion cohorts (n = 79) were 68% and 54%, respectively. CONCLUSION: ABBV-383 in patients with RRMM was well tolerated with an ORR of 68% at doses ≥ 40 mg. This novel therapy's promising preliminary antitumor activity in heavily pretreated patients warrants further clinical evaluation.

Effects of Long-Term Denosumab on Bone Histomorphometry and Mineralization in Women With Postmenopausal Osteoporosis.

Context: Denosumab is a potent antiresorptive agent that reduces fractures in postmenopausal women with osteoporosis. Objective: Determine effects of up to 10 years of denosumab on bone histology, remodeling, and matrix mineralization characteristics. Design and Setting: International, multicenter, randomized, double-blind trial [Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM)] with a long-term open-label extension. Patients: Postmenopausal women with osteoporosis (92 women in FREEDOM, 46 in extension) who provided iliac bone biopsies, including 11 who provided biopsies at multiple time points. Interventions: FREEDOM subjects were randomized 1:1 to subcutaneous denosumab 60 mg or placebo every 6 months for 3 years. Long-term extension subjects continued receiving denosumab, open-label, for 7 additional years. Outcomes: Bone histology, histomorphometry, matrix mineralization. Results: Ten-year denosumab biopsies showed normal histology. Bone histomorphometry indicated normal bone structure and reduced bone remodeling after 10 years of denosumab, similar to levels after 2 and/or 3 and 5 years of denosumab. The degree of mineralization of bone was increased and mineralization heterogeneity was reduced in the denosumab years 2/3 group vs placebo. Changes in these mineralization variables progressed from years 2/3 to year 5 of denosumab, but not thereafter. Conclusions: Denosumab for 2/3, 5, and 10 years was associated with normal histology, low bone remodeling rate, increased matrix mineralization, and lower mineralization heterogeneity compared with placebo. These variables were unchanged from year 5 to year 10. These data, in combination with the maintenance of low fracture rates for up to 10 years as previously reported with denosumab therapy, suggest that strong, prolonged remodeling inhibition does not impair bone strength.

A Prospective Cohort Study of Mineral Metabolism After Kidney Transplantation.

BACKGROUND: Kidney transplantation corrects or improves many complications of chronic kidney disease, but its impact on disordered mineral metabolism is incompletely understood. METHODS: We performed a multicenter, prospective, observational cohort study of 246 kidney transplant recipients in the United States to investigate the evolution of mineral metabolism from pretransplant through the first year after transplantation. Participants were enrolled into 2 strata defined by their pretransplant levels of parathyroid hormone (PTH), low PTH (>65 to ≤300 pg/mL; n = 112), and high PTH (>300 pg/mL; n = 134) and underwent repeated, longitudinal testing for mineral metabolites. RESULTS: The prevalence of posttransplant, persistent hyperparathyroidism (PTH >65 pg/mL) was 89.5%, 86.8%, 83.1%, and 86.2%, at months 3, 6, 9, and 12, respectively, among participants who remained untreated with cinacalcet, vitamin D sterols, or parathyroidectomy. The results did not differ across the low and high PTH strata, and rates of persistent hyperparathyroidism remained higher than 40% when defined using a higher PTH threshold greater than 130 pg/mL. Rates of hypercalcemia peaked at 48% at week 8 in the high PTH stratum and then steadily decreased through month 12. Rates of hypophosphatemia (<2.5 mg/dL) peaked at week 2 and then progressively decreased through month 12. Levels of intact fibroblast growth factor 23 decreased rapidly during the first 3 months after transplantation in both PTH strata and remained less than 40 pg/mL thereafter. CONCLUSIONS: Persistent hyperparathyroidism is common after kidney transplantation. Further studies should determine if persistent hyperparathyroidism or its treatment influences long-term posttransplantation clinical outcomes.

ERK1 and ERK2 regulate chondrocyte terminal differentiation during endochondral bone formation.

Chondrocytes in the epiphyseal cartilage undergo terminal differentiation prior to their removal through apoptosis. To examine the role of ERK1 and ERK2 in chondrocyte terminal differentiation, we generated Osterix (Osx)-Cre; ERK1(-/-) ; ERK2(flox/flox) mice (conditional knockout Osx [cKOosx]), in which ERK1 and ERK2 were deleted in hypertrophic chondrocytes. These cKOosx mice were grossly normal in size at birth, but by 3 weeks of age exhibited shorter long bones. Histological analysis in these mice revealed that the zone of hypertrophic chondrocytes in the growth plate was markedly expanded. In situ hybridization and quantitative real-time PCR analyses demonstrated that Matrix metalloproteinase-13 (Mmp13) and Osteopontin expression was significantly decreased, indicating impaired chondrocyte terminal differentiation. Moreover, Egr1 and Egr2, transcription factors whose expression is restricted to the last layers of hypertrophic chondrocytes in wild-type mice, were also strongly downregulated in these cKOosx mice. In transient transfection experiments in the RCS rat chondrosarcoma cell line, the expression of Egr1, Egr2, or a constitutively active mutant of MEK1 increased the activity of an Osteopontin promoter, whereas the MEK1-induced activation of the Osteopontin promoter was inhibited by the coexpression of Nab2, an Egr1 and Egr2 co-repressor. These results suggest that MEK1-ERK signaling activates the Osteopontin promoter in part through Egr1 and Egr2. Finally, our histological analysis of cKOosx mice demonstrated enchondroma-like lesions in the bone marrow that are reminiscent of human metachondromatosis, a skeletal disorder caused by mutations in PTPN11. Our observations suggest that the development of enchondromas in metachondromatosis may be caused by reduced extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK MAPK) signaling.

Clinical pharmacokinetics and pharmacodynamics of erythropoiesis-stimulating agents.

The cloning of the EPO gene in the early 1980s allowed for the development of recombinant erythropoietins and analogues [erythropoiesis-stimulating agents (ESAs)], offering an alternative to transfusion as a method of raising haemoglobin (Hb) levels, which have been used for more than 20 years to treat anaemia in millions of anaemic patients. There are now a number of ESAs available worldwide for the treatment of anaemia, approved for different routes of administration (intravenous and subcutaneous) and dosing intervals (three times weekly, weekly, biweekly and monthly). In this review, we discuss the pharmacokinetic characteristics, including absorption, distribution and elimination processes, across the different ESAs. Incomplete and slow lymphatic absorption, with limited extravascular distribution, and minor contributions of the target-mediated drug disposition to the overall elimination are the common characteristics across the marketed ESA. Additionally, we assess the similarities and differences of ESAs related to pharmacodynamics in the context of the different biomarkers used to monitor the magnitude and duration of the effect, and introduce the concept of the minimum effective concentration of the ESA. The relationship between the minimum effective concentration and the half-life suggests that the time during which drug concentrations are above the minimum effective concentration is the main determinant of ESA efficacy in increasing Hb levels. The tolerance phenomenon and its physiological mechanism and implications for ESA dosing are discussed. Finally, the areas of future clinical pharmacology research are envisioned.