Adult Autosomal Dominant Polycystic Kidney Disease Research Articles

#1891 Evaluating the safety and effectiveness of Tolvaptan for management of adult Korean ADPKD patients (ESSENTIAL study): final report

Abstract Background and Aims Tolvaptan, a selective vasopressin V2 receptor antagonist, was first approved by Korean FDA in 2015 as a treatment option in autosomal dominant polycystic kidney disease (ADPKD). In order to prescribe Tolvaptan safely and effectively, we designed the phase 4 clinical trial among Korean ADPKD patients with chronic kidney disease (CKD) stage 1-3. Method Korean patients aged 19 to 50 with rapidly progressing ADPKD were enrolled in the study. The dose titration was performed every one week for a total of 4 weeks. The patient was prescribed Tolvaptan with the maximum tolerable dose up to 120 mg per day. A total duration of Tolvaptan prescription was 24 months. The primary outcome was the incidence of treatment emergent adverse events (TEAE) including drug-induced liver injury (DILI). The secondary outcomes were the annual mean percent change of total kidney volume (TKV) and the annual mean change of estimated glomerular filtration rate (eGFR). Results A total of 117 patients were included in the analysis. Mean age was 38.7 ± 8.4 years old and male were predominant (58.1%). The average TKV was 2066 ± 1094 mL and mean eGFR was 79.7 ± 27.7 mL/min/1.73 m2. Mean duration of Tolvaptan exposure was 1.7 ± 0.6 years and the average daily dose of Tolvaptan was 94.4 ± 24.1 mg/day. A total of 489 treatment-emergent adverse events (TEAE) occurred in 106 (90.6%) patients during study duration. The drug-induced liver injury and aquaresis-related adverse events were two most common adverse events. A total of 17 DILI cases (14.5%) occurred during the study period and mostly within 18-month period. However, liver enzymes were normalized after drug discontinuation The patients with previous history of liver disease as well as those who were prescribed higher dose of Tolvaptan demonstrated higher frequency of DILI. Mean growth rate of TKV after Tolvaptan treatment was 4.5 ± 0.5% and mean eGFR decline rate was -3.0 ± 0.39 mL/min/1.73 m2/year. Comparing with the predicted value from calculation, Tolvaptan attenuated both TKV growth and eGFR decline rate. Conclusion This study is the first post-marketing survey assessing the safety and efficacy of Tolvaptan in Korean ADPKD patients. The incidence of DILI was higher than the previous studies and especially in those with liver disease and higher Tolvaptan prescription dose. While Tolvaptan can effectively reduce TKV and attenuate eGFR decline, the clinicians should be aware of higher frequency of DILI among Korean population.

#3971 INJURY INDUCED RENAL FIBROSIS PROMOTES CYSTOGENESIS AND CYST GROWTH IN ADULT MICE WITH AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims Acute kidney injury (AKI) is not a merely transient event, which can lead to a subsequent progression to chronic kidney disease (CKD). Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent inherited kidney disease caused by mutations in PKD1 or PKD2 gene. Previous studies showed that acute kidney injuries promote cystogenesis in adult mice with ADPKD. Fibrosis is a hallmark of AKI to CKD (AKI-CKD) transition, and positively correlated with renal cyst growth in humans. All these data imply a role of AKI-CKD transition in ADPKD.In this study, we aimed to determine the role of AKI-CKD transition in the ADPKD. Method We established AKI-CKD transition model by toxic or surgical injuries, and Pkd gene inactivation in adult mice was performed in different time point of AKI-CKD transition. The progression of renal fibrosis was shown by Western blotting analysis in toxic or surgical injury induced AKI-CKD transition model. Results We showed that renal injury before or after Pkd gene inactivation can both induce renal cyst formation in adult Pkd1 or Pkd2 mice, and the extent of cyst formation was correlated with the initial fibrosis level of three hits (injury and gene inactivation). Inactivation of Pkd1 gene at fibrosis recovery stage in surgery induced less cyst formation in adult Pkd1 mice. Enhanced renal fibrosis by repeated toxic injuries before gene inactivation accelerated renal cyst growth in Pkd1 mice. We further showed that the speed of cyst growth at the early stage in adult Pkd1 mice was decided by the baseline of renal fibrosis. Finally, we showed that conditional knockout of Ezh2 gene attenuated renal fibrosis and cyst growth in adult Pkd1 mice with established renal fibrosis. Conclusion Fibrotic responses in AKI-CKD transition is a driving force for renal cyst formation and growth in adult kidneys and inhibition of renal fibrosis through targeting EZH2 might be new therapeutic strategy for adult ADPKD.

Parasympathetic activity and total fibrotic kidney in autosomal-dominant polycystic kidney disease patients: a pilot study

PurposeRenin–angiotensin system hyperactivation in autosomal-dominant polycystic kidney disease (ADPKD) patients leads to early hypertension. Cystic enlargement probably causes parenchymal hypoxia, renin secretion, and endothelial dysfunction. Sympathetic and parasympathetic balance is altered in this condition, especially during the night, also affecting blood pressure circadian rhythm. Aim of this study was to evaluate sympathetic/parasympathetic balance using heart rate variability (HRV) parameters and find a correlation between HRV and renal damage progression, as total kidney volume enlargement, in ADPKD patients.MethodsSixteen adult ADPKD patients were enrolled in the study. Eleven patients (68.8%) were male, and the median age was 42 years (IQR 36–47.5). HRV parameters were calculated using 24 h-ECG Holter. A kidney magnetic resonance imaging (MRI) scan 3 Tesla was performed to evaluate total kidney volume (TKV) and total fibrotic volume (TFV).ResultsA statistically significant positive linear correlation was observed between length of kidneys and frequency domain parameters as low frequency (LF) (r = 0.595, p < 0.05) and LFday (r = 0.587, p < 0.05). Moreover, a statistically significant positive linear correlation exists between high frequency (HF) and TFV (r = 0.804, p < 0.01) or height-adjusted (ha) TFV (r = 0.801, p < 0.01). Finally, we found a statistically significant positive linear correlation between HFnight and TKV (r = 0.608, p < 0.05), ha-TKV (r = 0.685, p < 0.01), TFV (r = 0.594, p < 0.05), and ha-TFV (r = 0.615, p < 0.05).ConclusionWe suppose that the increase in TKV and TFV could lead to a parasympathetic tone hyperactivation, probably in response to hypoxic stress and vasoconstriction due to cystic enlargement.

Dehydration Accelerates Cytogenesis and Cyst Growth in Pkd1-/- Mice by Regulating Macrophage M2 Polarization.

Adult autosomal dominant polycystic kidney disease (ADPKD) has been shown to be related as a "third hit" to the occurrence of acute or chronic kidney injury. Here, we examined whether dehydration, as a common kidney risk factor, could cause cystogenesis in chronic-onset Pkd1-/- mice by regulating macrophage activation. First, we confirmed that dehydration accelerated cytogenesis in Pkd1-/- mice and that macrophages infiltrated the kidney tissues even earlier than macroscopic cyst formation. Then, microarray analysis suggested that glycolysis pathway may be involved in macrophage activation in Pkd1-/- kidneys under conditions of dehydration. Further, we confirmed glycolysis pathway was activated and lactic acid (L-LA) was overproduced in the Pkd1-/- kidney under conditions of dehydration. We have already proved that L-LA strongly stimulated M2 macrophage polarization and overproduction of polyamine in macrophage in vitro, and in the present study, we further discovered that M2 polarization-induced polyamine production shortened the primary cilia length by disrupting the PC1/PC2 complex. Finally, the activation of L-LA-arginase 1-polyamine pathway contributed to cystogenesis and progressive cyst growth in Pkd1-/- mice recurrently exposed to dehydration.

Low agreement between various eGFR formulae in pediatric and young adult ADPKD patients.

Young autosomal dominant polycystic kidney disease (ADPKD) patients are becoming the new target population for the development of new treatment options. Determination of a reliable equation for estimated glomerular filtration rate (eGFR) from early stages is needed with the promising potential interventional therapies. Prospective and longitudinal study on a cohort of 68 genotyped ADPKD patients (age range 0-23years) with long-term follow-up. Commonly used equations for eGFR were compared for their relative performance. The revised Schwartz formula (CKiD) showed a highly significant decline in eGFR with aging (- 3.31mL/min/1.73 m2/year, P < 0.0001). The recently updated equation by the Schwartz group (CKiDU25) showed a smaller (- 0.90mL/min/1.73 m2/year) but significant (P = 0.001) decline in eGFR with aging and also showed a significant sex difference (P < 0.0001), not observed by the other equations. In contrast, the full age spectrum (FAS) equations (FAS-SCr, FAS-CysC, and the combined) showed no age and sex dependency. The prevalence of hyperfiltration is highly dependent on the formula used, and the highest prevalence was observed with the CKiD Equation(35%). The most widely used methods to calculate eGFR in ADPKD children (CKiD and CKiDU25 equations) were associated with unexpected age or sex differences. The FAS equations were age- and sex-independent in our cohort. Hence, the switch from the CKiD to CKD-EPI equation at the transition from pediatric to adult care causes implausible jumps in eGFR, which could be misinterpreted. Having reliable methods to calculate eGFR is indispensable for clinical follow-up and clinical trials. A higher resolution version of the Graphical abstract is available as Supplementary information.

Association of Longitudinal Urinary Metabolic Biomarkers With ADPKD Severity and Response to Metformin in TAME-PKD Clinical Trial Participants

Dysregulated cellular metabolism contributes to autosomal dominant polycystic kidney disease (ADPKD) pathogenesis. The Trial of Administration of Metformin in Polycystic Kidney Disease (TAME-PKD) tested the effects of metformin treatment over 2 years in adult ADPKD patients with mild-moderate disease severity. Metformin was found to be safe and tolerable with an insignificant trend toward reduced estimated glomerular filtration rate (eGFR) decline compared to placebo. Here we tested whether targeted urinary metabolic biomarkers measured in TAME-PKD participants correlated with disease progression, severity, and metformin treatment in cross-sectional and longitudinal analyses. Concentrations of total protein, targeted metabolites (lactate, pyruvate, and succinate), and glycolytic enzymes (pyruvate kinase-M2, lactate dehydrogenase-A, and pyruvate dehydrogenase kinase-1) were measured and normalized by creatinine or osmolality in urine specimens and compared with height-adjusted total kidney volume (htTKV) and eGFR at the different study timepoints. In cross-sectional analyses utilizing placebo group data, urinary succinate normalized by creatinine negatively correlated with ln (htTKV), whereas protein excretion strongly positively correlated with ln (htTKV), and negatively correlated with eGFR. Significant time-varying negative associations occurred with eGFR and the lactate/pyruvate ratio and with urine protein normalized by osmolality, indicating correlations of these biomarkers with disease progression. In secondary analyses, urinary pyruvate normalized by osmolality was preserved in metformin-treated participants but declined in placebo over the 2-year study period with a significant between-arm difference, suggesting time-dependent urinary pyruvate changes may serve as a discriminator for metformin treatment effects in this study population. Proteinuria with enhanced glycolytic and reduced oxidative metabolic markers generally correlated with disease severity and risk of progression in the TAME-PKD study population.

Echocardiographic Abnormalities in Autosomal Dominant Polycystic Kidney Disease (ADPKD) Patients.

Cardiovascular abnormalities, such as left ventricular hypertrophy and valvular disorders, particularly mitral valve prolapse, have been described as highly prevalent among adult patients with autosomal dominant polycystic kidney disease (ADPKD). The present study aimed to assess echocardiographic parameters in a large sample of both normotensive and hypertensive ADPKD patients, regardless of kidney function level, and evaluate their association with clinical and laboratorial parameters. A retrospective study consisted of the analysis of clinical, laboratorial, and transthoracic echocardiograms data retrieved from the medical records of young adult ADPKD outpatients. A total of 294 patients (120 M/174 F, 41.0 ± 13.8 years old, 199 hypertensive and 95 normotensive) with a median estimated glomerular filtration rate (eGFR) of 75.5 mL/min/1.73 m2 were included. The hypertensive group (67.6%) was significantly older and exhibited significantly lower eGFR than the normotensive one. Increased left ventricular mass index (LVMI) was seen in 2.0%, mitral valve prolapse was observed in 3.4%, mitral valve regurgitation in 15.3%, tricuspid valve regurgitation in 16.0%, and aortic valve regurgitation in 4.8% of the whole sample. The present study suggested that the prevalence of mitral valve prolapse was much lower than previously reported, and increased LVMI was not seen in most adult ADPKD patients.

Outcomes from the Northeast England cohort of autosomal dominant polycystic kidney disease (ADPKD) patients on tolvaptan.

Autosomal dominant polycystic kidney disease (ADPKD) is a cause of end-stage kidney disease (ESKD). The vasopressin V2-receptor antagonist tolvaptan has been shown within randomized clinical trials to slow down decline of kidney function in patients with ADPKD at risk of rapid progression. We performed a retrospective review of a Northeast England cohort of adult ADPKD patients who had been established on tolvaptan therapy to determine its efficacy in a real-world clinic setting. Other inclusion criteria involved a pre-treatment decline in greater than 2.5 ml/min/1.73m2/year based on readings for a 3 year period, and ability to tolerate and maintain tolvaptan treatment for at least 12 months. We calculated based on eGFR slopes, predicted time to reach ESKD with and without tolvaptan therapy. The cohort of patients included 21 from the Northeast of England. The mean rate of eGFR decline prior to treatment was -6.02 ml/min/1.73m2/year for the cohort. Following tolvaptan treatment, the average decline in eGFR was reduced to -2.47 ml/min/1.73m2/year, gaining a mean 8 years and 4 months delay to reach ESKD. The majority of patients (n=19) received and tolerated full dose tolvaptan (90 mg/30 mg). The real-life use of tolvaptan gave a dramatic improvement in eGFR slopes, much more than previously reported in clinical studies. These effects may be in part due to careful patient identification, selection and inclusion of patients who were able to tolerate tolvaptan therapy, excellent compliance with medication and a "tolvaptan clinic" effect where great personal care was given to these patients.

Ttc21b deficiency attenuates autosomal dominant polycystic kidney disease in a kidney tubular- and maturation-dependent manner

Primary cilia are sensory organelles built and maintained by intraflagellar transport (IFT) multiprotein complexes. Deletion of several IFT-B genes attenuates polycystic kidney disease (PKD) severity in juvenile and adult autosomal dominant polycystic kidney disease (ADPKD) mouse models. However, deletion of an IFT-A adaptor, Tulp3, attenuates PKD severity in adult mice only. These studies indicate that dysfunction of specific cilia components has potential therapeutic value. To broaden our understanding of cilia dysfunction and its therapeutic potential, we investigate the role of global deletion of an IFT-A gene, Ttc21b, in juvenile and adult mouse models of ADPKD. Both juvenile (postnatal day 21) and adult (six months of age) ADPKD mice exhibited kidney cysts, increased kidney weight/body weight ratios, lengthened kidney cilia, inflammation, and increased levels of the nutrient sensor, O-linked β-N-acetylglucosamine (O-GlcNAc). Deletion of Ttc21b in juvenile ADPKD mice reduced cortical collecting duct cystogenesis and kidney weight/body weight ratios, increased proximal tubular and glomerular dilations, but did not reduce cilia length, inflammation, nor O-GlcNAc levels. In contrast, Ttc21b deletion in adult ADPKD mice markedly attenuated kidney cystogenesis and reduced cilia length, inflammation, and O-GlcNAc levels. Thus, unlike IFT-B, the effect of Ttc21b deletion in mouse models of ADPKD is development-specific. Unlike an IFT-A adaptor, deleting Ttc21b in juvenile ADPKD mice is partially ameliorative. Thus, our studies suggest that different microenvironmental factors, found in distinct nephron segments and in developing versus mature stages, modify ciliary homeostasis and ADPKD pathobiology. Further, elevated levels of O-GlcNAc, which regulates cellular metabolism and ciliogenesis, may be a pathological feature of ADPKD.

Increased Body Fat and Organic Acid Anions Production Are Associated with Larger Kidney Size in ADPKD.

Background and Objectives: A high body mass index (BMI) is associated with the progression of autosomal dominant polycystic kidney disease (ADPKD). However, body fat (BF), which is another adiposity marker, has not yet been studied. Excessive weight may promote elevation in the endogenous synthesis of organic acid (OA) anions. Accordingly, we aimed to investigate the possible association of the aforementioned markers with kidney volume and renal function in patients with ADPKD. Materials and Methods: We conducted a retrospective cohort study of adult ADPKD outpatients involving clinical, serum, and urinary laboratorial data and body composition assessments retrieved from their medical records. BF was estimated by skinfold thickness (mm) on the non-dominant arm and was considered as normal or high for each sex. Total kidney volume (TKV) and height-adjusted volume (htTKV) were measured by magnetic resonance imaging. The annual estimated glomerular filtration rate (eGFR) slope was analyzed during a median follow-up time of 6 (5.0–7.0) years to calculate rapid progression (decline in renal function ≥2.5 mL/min/year over 5 years). Results: A total of 104 patients were included (41.9 ± 11.9 years old, 38.5% men), with 62.5% of the patients classified as high BF. The High BF group presented higher levels of OA, glycosylated hemoglobin (HbA1c), C-reactive protein (CRP), 24 h urinary sodium (UNa), and htTKV, and lower eGFR than those with a normal BF. In the multivariate linear regression, the associated variables with TKV were high BF, OA and BMI (std. β 0.47, p < 0.05; std. β 0.36, p = 0.001; std. β 0.25, p = 0.01, respectively). In the binary logistic regression, when adjusted for potential confounders, UNa was the only parameter associated with an increased risk of eGFR decline ≥2.5 mL/min/year (OR 1.02, 95% CI 1.01–1.03, p = 0.02). Conclusions: Increased body fat and endogenous production of organic acid anions are associated with larger kidney size in ADPKD but not with a decline in renal function.

Endocan Levels in Children with Polycystic Kidney Disease

Objective: Autosomal dominant polycystic kidney disease (ADPKD) is a common renal disorder that is characterized by hypertension and renal failure. Recently, it has been emphasized that endocan which is an endothelial dysfunction biomarker, could increase in many renal diseases. High endocan levels have also been reported in hypertensive ADPKD adult patients with renal failure. However, studies are limited on children. In this study, we investigated the serum endocan levels in normotensive ADPKD children with normal renal function. Material and Methods: The study consisted of 20 ADPKD children without hypertension and renal failure as a patient group, and 20 healthy age- and sex-matched children as a control group. Serum endocan levels were determined by enzyme-linked immunosorbent assay techniques and compared between the two groups. Results: The mean age of patients was 9.9±4.12 years, and the mean age of the control group was 10.2±3.83 years. There was no significant difference between the two groups in terms of gender, age, and BMI (p=0.751, p=0.813, p=0.781, respectively). The leukocyte (p=0.449), hemoglobin (p=0.337), platelets (p=0.134), serum uric acid (p=0.671) and serum creatinine (p=0.074) levels, eGFR (p=0.459) were not significantly differed between groups. The mean serum endocan level in the PKD group was 345.8±169.5 pg/ml, and in the control group was 448.61±258.2 pg/ml. Serum endocan levels did not change between groups (p=0.159). Conclusion: Unlike the adult ADPKD patients, this study suggested that serum endocan level was normal in children with ADPKD without hypertension and renal failure.

Elamipretide treatment during pregnancy ameliorates the progression of polycystic kidney disease in maternal and neonatal mice with PKD1 mutations

Pregnancy is proposed to aggravate cyst progression in autosomal dominant polycystic kidney disease (ADPKD) but Tolvaptan, the only FDA-approved drug for adult ADPKD, is not recommended for pregnant ADPKD patients because of potential fetal harm. Since pregnancy itself may increase the risk for ADPKD progression, we investigated the safety and efficacy of Elamipretide, a mitochondrial-protective tetrapeptide. Elamipretide was found to ameliorate the progression of kidney disease in pregnant Pkd1RC/RC mice, in parallel with attenuation of ERK1/2 phosphorylation and improvement of mitochondrial supercomplex formation. Furthermore, Elamipretide was found to pass through the placenta and breast milk and ameliorate aggressive infantile polycystic kidney disease without any observed teratogenic or harmful effect. Elamipretide has an excellent safety profile and is currently tested in multiple phase II and phase III clinical trials. These preclinical studies support a potential clinical trial of Elamipretide for the treatment of ADPKD, particularly for patients that cannot take Tolvaptan.

The chloride channel CFTR is not required for cyst growth in an ADPKD mouse model.

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the development of bilateral renal cysts which enlarge continuously, leading to compression of adjacent intact nephrons. The growing cysts lead to a progressive decline in renal function. Cyst growth is driven by enhanced cell proliferation and chloride secretion into the cyst lumen. Chloride secretion is believed to occur mainly by the cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR), with some contribution by the calcium-activated chloride channel TMEM16A. However, our previous work suggested TMEM16A as a major factor for renal cyst formation. The contribution of CFTR to cyst formation has never been demonstrated in an adult ADPKD mouse model. We used mice with an inducible tubule-specific Pkd1 knockout, which consistently develop polycystic kidneys upon deletion of Pkd1. Cellular properties, ion currents, and cyst development in these mice were compared with that of mice carrying a co-deletion of Pkd1 and Cftr. Knockout of Cftr did not reveal any significant impact on cyst formation in the ADPKD mouse model. Furthermore, knockout of Cftr did not attenuate the largely augmented cell proliferation observed in Pkd1 knockout kidneys. Patch clamp analysis on primary renal epithelial cells lacking expression of Pkd1 indicated an only marginal contribution of CFTR to whole cell Cl- currents, which were clearly dominated by calcium-activated TMEM16A currents. In conclusion, CFTR does not essentially contribute to renal cyst formation in mice caused by deletion of Pkd1. Enhanced cell proliferation and chloride secretion is caused primarily by upregulation of the calcium-activated chloride channel TMEM16A.

Rationale and study protocol of ACQUIRE, a prospective, observational study measuring quality of life, treatment preference and treatment satisfaction of autosomal dominant polycystic kidney disease (ADPKD) patients in Europe

BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is considered the most common inherited renal disease. Patient-Reported Outcomes (PROs) and patient experience in ADPKD are difficult to quantify and have not been well studied, particularly in the early stages of the disease. There is evidence to suggest that early-stage ADPKD patients have a lower Health-Related Quality of Life (HRQoL) than the general population due to the signs and symptoms of early-stage ADPKD. However, no research has been carried out on the HRQoL of early-stage ADPKD patients using validated ADPKD-specific PRO measures. Additionally, a new disease progression delaying treatment option has recently emerged for ADPKD. Patient preference for this treatment and unmet treatment needs have not yet been investigated.MethodsThe ACQUIRE study is a prospective, observational study investigating the influence of early-stage ADPKD-related symptoms and treatments on PROs. It aims to collect real-world data on patient demographics, treatment patterns, clinical outcomes, and PROs such as HRQoL, treatment satisfaction and treatment preference in early-stage ADPKD. Adult ADPKD patients in stages 1–3 of chronic kidney disease (CKD) with evidence of rapidly progressing disease are being recruited from seven European countries. At baseline and every 3 months, for a follow-up period of 18 months, general and disease-specific questionnaires are completed remotely to capture patients’ own assessment of their overall and ADPKD-related HRQoL. A Discrete Choice Experiment (DCE) is also used to investigate the value patients place on different attributes of hypothetical treatment options (e.g. treatment outcomes, side effects) and the role each attribute plays in determining overall patient treatment preference.DiscussionThe results of this study will highlight the real-world effects of ADPKD-related challenges on PROs including HRQoL, treatment experience and satisfaction; and help physicians gain greater insight into likely disease outcomes based on early-stage patient symptoms and patients’ experience with treatment. Data captured by the DCE may inform ADPKD treatment decision-making from a patient perspective. The DCE will also provide insights into which patients are more likely to perceive benefit from treatments based on the value and trade-offs they place on specific treatment attributes.Trial registrationNCT02848521.Protocol Number/Version: 156–303-00096/Final

SO090EVALUATING PAIN IN AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims Chronic pain is prevalent in Autosomal Dominant Polycystic Kidney Disease (ADPKD) and is associated with a substantial quality of life burden. Literature describing ADPKD-related chronic pain (ACP) is limited, and generic pain management strategies are suboptimal with patients often reporting inadequate relief. Furthermore, the absence of a validated and widely accepted pain assessment tool (PAT) in ADPKD has posed a significant barrier to better pain management and research. We established an ADPKD PAT (APAT) and confirmed its feasibility and validity through administration to ADPKD patients participating in a randomised high water intake trial (NCT02933268). Method A collaboration of key stakeholders (patients, ADPKD experts, trialists and pain specialists) constructed an ADPKD pain conceptual framework consisting of eight prioritized pain assessment domains. We constructed an APAT from components of previously validated pain assessment tools covering each of the prioritized pain domains. The finalized APAT was administered to participants in a feasibility trial which randomised adult ADPKD patients with an eGFR≥20mls/min/1.73m2 to prescribed high water intake (HW) or ad libitum water intake (AW group) over eight weeks. Participants were asked to complete the APAT at least twice (baseline and week 8), although more frequent submissions were permitted. Results 93% (39/42) of trial participants with CKD stages 1-4 completed a total of 129 questionnaires. Each participant completed a median of 3 (range 1-10) questionnaires. In terms of baseline characteristics; mean age of respondents was 47±13 years, 90% (35) were White British ethnicity, and 59% (23) were female. Median disease duration was 14.2 (IQR 7.0-25.9) years, 69% had enlarged kidneys, 64% had hypertension and hepatic cysts were present in 59%. Pain (52%) and associated analgesic use (29%) were prevalent. Participants with pain were more likey to report interference with mobility (25% vs 0%), self-care (20% vs 0%) and usual activities (31% vs 1%) compared to those with no pain (p&amp;lt;0.001. Pain was also associated with a higher risk of anxiety and depression (RR 2.97, CI 1.70-5.20, p=0.000). Pain severity was predicted by traditional risk factors of disease progression including increasing age (OR 1.07, p=0.009), eGFR&amp;lt;60mls/min/1.73m2 (OR 5.45, p=0.021), and hypertension (OR 12.11, p=0.007), but not kidney size, consistent with findings of previous studies. Neuropathic descriptors were not commonly used, while continuous and intermittent descriptors were more frequently selected by patients to describe their pain quality (figure). The APAT achieved good internal consistency (Cronbach’s alpha coefficient =0.91) and test-retest reliability was demonstrated with domain intra-class correlation coefficients ranging from 0.62-0.90. Conclusion A bespoke APAT including components of previously validated pain assessment tools was reliable in evaluating pain in patients with ADPKD, and was acceptable to participants. Pain was prevalent among participants and associated with a substantial emotional and physical burden. The APAT represents a viable instrument for standardised evaluation of ADPKD pain in observational and interventional research.

High water vs. ad libitum water intake for autosomal dominant polycystic kidney disease: a randomized controlled feasibility trial.

Background Vasopressin stimulates cyst growth in autosomal dominant polycystic kidney disease (ADPKD) and is a key therapeutic target. Evaluation of high water intake as an alternative to pharmacological vasopressin blockade is supported by patients. However feasibility, safety and adherence-promoting strategies required to deliver this remain unknown. Aims Assess the feasibility of a definitive randomized high water intake trial in ADPKD. Methods In this prospective open-label randomized trial, adult ADPKD patients with eGFR ≥ 20 ml/min/1.73 m2 were randomized to prescribed high water (HW) intake targeting urine osmolality (UOsm) ≤270 mOsm/kg, or ad libitum (AW) intake (UOsm >300 mOsm/kg). Self-management strategies including home-monitoring of urine-specific gravity (USG) were employed to promote adherence. Results We enrolled 42 participants, baseline median eGFR (HW 68.4 [interquartile range (IQR) 35.9-107.2] vs. AW 75.8 [IQR 59.0-111.0 ml/min/1.73 m2, P = 0.22) and UOsm (HW 353 [IQR 190-438] vs. AW 350 [IQR 240-452] mOsm/kg, P = 0.71) were similar between groups. After 8 weeks, 67% in the HW vs. 24% in AW group achieved UOsm ≤270 mOsm/kg, P = 0.001. HW group achieved lower UOsm (194 [IQR 190-438] vs. 379 [IQR 235-503] mOsm/kg, P = 0.01) and higher urine volumes (3155 [IQR 2270-4295] vs. 1920 [IQR 1670-2960] ml/day, P = 0.02). Two cases of hyponatraemia occurred in HW group. No acute GFR effects were detected. In total 79% (519/672) of USG were submitted and 90% (468/519) were within target. Overall, 17% withdrew during the study. Conclusion DRINK demonstrated successful recruitment and adherence leading to separation between treatment arms in primary outcomes. These findings suggest a definitive trial assessing the impact of high water on kidney disease progression in ADPKD is feasible.

High water vs. ad libitum water intake for autosomal dominant polycystic kidney disease: a randomized controlled feasibility trial.

BackgroundVasopressin stimulates cyst growth in autosomal dominant polycystic kidney disease (ADPKD) and is a key therapeutic target. Evaluation of high water intake as an alternative to pharmacological vasopressin blockade is supported by patients. However feasibility, safety and adherence-promoting strategies required to deliver this remain unknown.AimsAssess the feasibility of a definitive randomized high water intake trial in ADPKD.MethodsIn this prospective open-label randomized trial, adult ADPKD patients with eGFR ≥ 20 ml/min/1.73 m2 were randomized to prescribed high water (HW) intake targeting urine osmolality (UOsm) ≤270 mOsm/kg, or ad libitum (AW) intake (UOsm >300 mOsm/kg). Self-management strategies including home-monitoring of urine-specific gravity (USG) were employed to promote adherence.ResultsWe enrolled 42 participants, baseline median eGFR (HW 68.4 [interquartile range (IQR) 35.9–107.2] vs. AW 75.8 [IQR 59.0–111.0 ml/min/1.73 m2, P = 0.22) and UOsm (HW 353 [IQR 190–438] vs. AW 350 [IQR 240–452] mOsm/kg, P = 0.71) were similar between groups. After 8 weeks, 67% in the HW vs. 24% in AW group achieved UOsm ≤270 mOsm/kg, P = 0.001. HW group achieved lower UOsm (194 [IQR 190–438] vs. 379 [IQR 235–503] mOsm/kg, P = 0.01) and higher urine volumes (3155 [IQR 2270–4295] vs. 1920 [IQR 1670–2960] ml/day, P = 0.02). Two cases of hyponatraemia occurred in HW group. No acute GFR effects were detected. In total 79% (519/672) of USG were submitted and 90% (468/519) were within target. Overall, 17% withdrew during the study.ConclusionDRINK demonstrated successful recruitment and adherence leading to separation between treatment arms in primary outcomes. These findings suggest a definitive trial assessing the impact of high water on kidney disease progression in ADPKD is feasible.

The association of serum angiogenic growth factors with renal structure and function in patients with adult autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a common congenital chronic kidney disease (CKD). We report here the relationship of serum angiopoietin-1 (Ang-1), Ang-2, and vascular endothelial growth factor (VEGF) with total kidney volume (TKV), total cyst volume (TCV), and renal failure in adult ADPKD patients at various stages of CKD. This cross-sectional study was conducted with 50 patients diagnosed with ADPKD and a control group of 45 age-matched healthy volunteers. In patient group, TKV and TCV were determined with upper abdominal magnetic resonance imaging, whereas in controls, TKV was determined with ultrasonography according to ellipsoid formula. Renal function was assessed with serum creatinine, estimated glomerular filtration rate (eGFR), and spot urinary protein/creatinine ratio (UPCR). Ang-1, Ang-2, and VEGF were measured using enzyme-linked immunosorbent assay. Patients with ADPKD had significantly higher TKV (p < 0.001) and UPCR (p < 0.001), and lower eGFR (p ≤ 0.001) compared to the controls. Log10Ang-2 was found to be higher in ADPKD patients at all CKD stages. Multiple linear regression analysis showed that there was no association between log10Ang-1, log10Ang-2, or log10VEGF and creatinine, eGFR, UPCR, log10TKV (p > 0.05). There was no association of serum angiogenic growth factors with TKV or renal failure in ADPKD patients. Increased serum Ang-2 observed in stages 1-2 CKD suggests that angiogenesis plays a role in the progression of early stage ADPKD, but not at later stages of the disease. This may be explained by possible cessation of angiogenesis in advanced stages of CKD due to the increased number of sclerotic glomeruli.

Evidence for Bone and Mineral Metabolism Alterations in Children With Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease. Hypophosphatemia was demonstrated in adult patients with preserved renal function, together with high fibroblast growth factor 23 (FGF23) and low soluble Klotho levels. The latter explained the relative FGF23 hyporesponsiveness in this cohort. Evaluating phosphate and bone mineral metabolism in children with ADPKD compared with what is known in adult ADPKD patients. Observational cross-sectional study. Multicenter study via ambulatory care in tertiary centers. Ninety-two children with ADPKD (52 males; mean ± standard deviation age, 10.2 ± 5.0 years) and 22 healthy controls (HCs, 10 males; mean ± standard deviation age, 10.3 ± 4.1 years). The predictor was early ADPKD stage. Bone mineral metabolism and renal phosphate handling were the main outcome measures. Performed measurements were serum phosphate, tubular maximum phosphorus reabsorption per glomerular filtration rate, FGF23, soluble Klotho, sclerostin, and bone alkaline phosphatase. ADPKD children had significantly lower serum phosphate levels compared with HC. Low tubular maximum phosphorus reabsorption per glomerular filtration rate was observed in 24% of patients, although not significantly different from HC. Serum FGF23 and soluble Klotho levels were comparable between patients and HC. In addition, we showed decreased bone alkaline phosphatase levels in ADPKD children, suggesting suppressed bone formation. This report demonstrates hypophosphatemia and suppressed bone formation in a pediatric ADPKD cohort, with preserved renal function, compared with HC. Although FGF23 levels were not different from controls, they should be considered inappropriate, given the concomitant hypophosphatemia. Further studies are required to elucidate underlying pathophysiology and potential clinical consequences.

Expanding the role of vasopressin antagonism in polycystic kidney diseases: From adults to children?

Polycystic kidney disease (PKD) encompasses a group of genetic disorders that are common causes of renal failure. The two classic forms of PKD are autosomal recessive polycystic kidney disease (ARPKD) and autosomal dominant polycystic kidney disease (ADPKD). Despite their clinical differences, ARPKD and ADPKD share many similarities. Altered intracellular Ca2+ and increased cyclic adenosine monophosphate (cAMP) concentrations have repetitively been described as central anomalies that may alter signaling pathways leading to cyst formation. The vasopressin V2 receptor (V2R) antagonist tolvaptan lowers cAMP in cystic tissues and slows renal cystic progression and kidney function decline when given over 3years in adult ADPKD patients. Tolvaptan is currently approved for the treatment of rapidly progressive disease in adult ADPKD patients. On the occasion of the recent initiation of a clinical trial with tolvaptan in pediatric ADPKD patients, we aim to describe the most important aspects in the literature regarding the AVP-cAMP axis and the clinical use of tolvaptan in PKD.