Tolvaptan and Kidney Pain in Patients With Autosomal Dominant Polycystic Kidney Disease: Secondary Analysis From a Randomized Controlled Trial

Interventions for preventing the progression of autosomal dominant polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the leading inherited cause of kidney disease. Clinical management has historically focused on symptom control and reducing associated complications. Improved understanding of the molecular and cellular mechanisms involved in kidney cyst growth and disease progression has resulted in new pharmaceutical agents targeting disease pathogenesis and preventing disease progression. However, the role of disease-modifying agents for all people with ADPKD is unclear. This is an update of a review first published in 2015.

OBJECTIVES

We aimed to evaluate the benefits and harms of interventions to prevent the progression of ADPKD and the safety based on patient-important endpoints, defined by the Standardised Outcomes in NephroloGy-Polycystic Kidney Disease (SONG-PKD) core outcome set, and general and specific adverse effects.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies up to 13 August 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing any interventions for preventing the progression of ADPKD with other interventions, placebo, or standard care were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study risks of bias and extracted data. Summary estimates of effects were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 57 studies (8016 participants) that investigated 18 pharmacological interventions (vasopressin 2 receptor (V2R) antagonists, antihypertensive therapy, mammalian target of rapamycin (mTOR) inhibitors, somatostatin analogues, antiplatelet agents, eicosapentaenoic acids, statins, kinase inhibitors, diuretics, anti-diabetic agents, water intake, dietary intervention, and supplements) in this review. Compared to placebo, the V2R antagonist tolvaptan probably preserves eGFR (3 studies, 2758 participants: MD 1.26 mL/min/1.73 m2, 95% CI 0.73 to 1.78; I2 = 0%) and probably slows total kidney volume (TKV) growth in adults (1 study, 1307 participants: MD -2.70 mL/cm, 95% CI -3.24 to -2.16) (moderate certainty evidence). However, there was insufficient evidence to determine tolvaptan's impact on kidney failure and death. There may be no difference in serious adverse events; however, treatment probably increases nocturia, fatigue and liver enzymes, may increase dry mouth and thirst, and may decrease hypertension and urinary and upper respiratory tract infections. Data on the impact of other therapeutic interventions were largely inconclusive. Compared to placebo, somatostatin analogues probably decrease TKV (6 studies, 500 participants: SMD -0.33, 95% CI -0.51 to -0.16; I2 = 11%), probably have little or no effect on eGFR (4 studies, 180 participants: MD 4.11 mL/min/1.73 m3, 95% CI -3.19 to 11.41; I2 = 0%) (moderate certainty evidence), and may have little or no effect on kidney failure (2 studies, 405 participants: RR 0.64, 95% CI 0.16 to 2.49; I2 = 39%; low certainty evidence). Serious adverse events may increase (2 studies, 405 participants: RR 1.81, 95% CI 1.01 to 3.25; low certainty evidence). Somatostatin analogues probably increase alopecia, diarrhoea or abnormal faeces, dizziness and fatigue but may have little or no effect on anaemia or infection. The effect on death is unclear. Targeted low blood pressure probably results in a smaller per cent annual increase in TKV (1 study, 558 participants: MD -1.00, 95% CI -1.67 to -0.33; moderate certainty evidence) compared to standard blood pressure targets, had uncertain effects on death, but probably do not impact other outcomes such as change in eGFR or adverse events. Kidney failure was not reported. Data comparing antihypertensive agents, mTOR inhibitors, eicosapentaenoic acids, statins, vitamin D compounds, metformin, trichlormethiazide, spironolactone, bosutinib, curcumin, niacinamide, prescribed water intake and antiplatelet agents were sparse and inconclusive. An additional 23 ongoing studies were also identified, including larger phase III RCTs, which will be assessed in a future update of this review.

AUTHORS' CONCLUSIONS

Although many interventions have been investigated in patients with ADPKD, at present, there is little evidence that they improve patient outcomes. Tolvaptan is the only therapeutic intervention that has demonstrated the ability to slow disease progression, as assessed by eGFR and TKV change. However, it has not demonstrated benefits for death or kidney failure. In order to confirm the role of other therapeutic interventions in ADPKD management, large RCTs focused on patient-centred outcomes are needed. The search identified 23 ongoing studies, which may provide more insight into the role of specific interventions.

The safety and efficacy of tolvaptan in the treatment of patients with autosomal dominant polycystic kidney disease: A systematic review and meta-analysis

BACKGROUND

The irreversible progression of autosomal dominant polycystic kidney disease (ADPKD) to end-stage renal disease (ESRD) is delayed by tolvaptan. Therefore, we aim to systematically estimate and evaluate the efficacy and safety of tolvaptan in the treatment of ADPKD.

METHODS

Two reviewers independently searched all published randomized controlled trials studies in PubMed, EMBASE, Web of Science and Cochrane databases, extracted data, assessed bias risk and rated the quality of evidence. Data were analyzed by the RevMan software.

RESULTS

We identified 8 trials including 2135 patients. Both of the decline of estimated glomerular filtration rate (eGFR) [MD=1.89, 95% CI (0.74, 3.04), P=0.001] and total kidney volume (TKV) [MD=-3.32, 95% CI (-4.57, -2.07), P<0.001] were delayed in tolvaptan group compared with placebo group in ADPKD patients. The use of tolvaptan delayed TKV progression in the different-month subgroups [MD=-69.99, 95% CI (-91.05, -48.94), P<0.001]. Tolvaptan reduced renal pain [RR=0.66, 95% CI (0.54, 0.81), P<0.001] and hematuria events [RR=0.55, 95% CI (0.41, 0.74), P<0.001] in ADPKD patients. However, the prevalence of thirst [RR=2.75, 95% CI (2.34, 3.24), P<0.001] and nocturia events [RR=3.01, 95% CI (1.27, 7.11), P=0.01] were increased in tolvaptan group. There is no significant difference of hypertension events [RR=0.92, 95% CI (0.82, 1.03), P=0.13] in tolvaptan group compared placebo group.

CONCLUSIONS

This meta-analysis suggests that tolvaptan may improve clinical progression in patients with ADPKD without significantly increasing the risk of adverse reactions.

Efficacy and safety of tolvaptan versus placebo in the treatment of patients with autosomal dominant polycystic kidney disease: a meta-analysis

OBJECTIVE

The objective of this meta-analysis was to compare the efficacy and drug safety of tolvaptan with placebo for autosomal dominant polycystic kidney disease (ADPKD).

METHODS

The PubMed, Embase, and Cochrane Library databases were searched from inception to September 10, 2021. Eligible studies comparing tolvaptan and placebo in the treatment of patients with ADPKD were included. Data were analysed using Review Manager Version 5.3.

RESULTS

Thirteen studies involving 3575 patients were included in the meta-analysis. Compared with placebo, tolvaptan had a better effect on delaying eGFR decline (MD 1.27, 95% CI 1.24-1.29, P < 0.01) and TKV increase (MD - 3.01, 95% CI - 3.55 to - 2.47, P < 0.01) in ADPKD treatment. Additionally, tolvaptan reduced the incidence of complications such as renal pain (OR 0.71, 95% CI 0.58-0.87, P < 0.01), urinary tract infection (OR 0.69, 95% CI 0.54-0.89, P < 0.01), haematuria (OR 0.68, 95% CI 0.51-0.89, P < 0.01), and hypertension (OR 0.66, 95% CI 0.52-0.82, P < 0.01). However, tolvaptan was associated with a higher incidence rate of adverse events such as thirst (OR 8.48 95% CI 4.53-15.87, P < 0.01), polyuria (OR 4.71, 95% CI 2.17-10.24, P < 0.01), and hepatic injury (OR 4.56, 95% CI 2.51-8.29, P < 0.01).

CONCLUSION

Tolvaptan can delay eGFR decline and TKV increase and reduce complications such as renal pain, urinary tract infection, haematuria, and hypertension in the treatment of ADPKD. However, tolvaptan increases the adverse effects of thirst, polyuria and hepatic injury.

Health Disparities in Kidney Failure Among Patients With Autosomal Dominant Polycystic Kidney Disease: A Cross-Sectional Study

Rationale & Objective

Understanding potential differences in patterns of kidney failure among patients with autosomal dominant polycystic kidney disease (ADPKD) may provide insights into improving disease management. We sought to characterize patients with ADPKD and kidney failure across different race/ethnicities.

Study Design

Cross-sectional study.

Setting & Participants

Kaiser Permanente Southern California members diagnosed with ADPKD between January1, 2002, and December 31, 2018.

Exposure

ADPKD.

Outcome

Kidney failure, dialysis, or receipt of kidney transplant.

Analytical Approach

Differences in characteristics by race/ethnicity were assessed using analysis of variance F test and χ² test. To compare the range and distribution of the average age at onset of kidney failure by race/ethnicity and sex, we used box plots and confidence intervals. Multivariable logistic regression was used to estimate OR for kidney transplant.

Results

Among 3,677 ADPKD patients, 1,027 (27.3%) had kidney failure. The kidney failure cohort was comprised of Black (n=138; 30.7%), White (n=496; 30.6%), Hispanic (n=306; 24.7%), and Asian (n=87; 23.6%) patients. Hispanic patients had the youngest mean age of kidney failure onset (50 years) compared to Black (56 years) and White (57 years) patients. Black (44.2%; OR, 0.72) and Hispanic (49.7%; OR, 0.65) patients had lower rates of kidney transplantation compared to White (53.8%) patients. Preemptive kidney transplantations occurred in 15.0% of patients.

Limitations

Retrospective study design and possible misclassification of ADPKD cases. Kidney function calculations were based on equations incorporating race, potentially overestimating kidney function in African Americans. The study was conducted within a single, integrated health care system in 1 geographic region and may not be generalizable to all ADPKD patients.

Conclusions

Among a large diverse ADPKD population, we observed racial/ethnic differences in rates of kidney failure, age of kidney failure onset, and rates of kidney transplantation. Our real-world ADPKD cohort provides insight into racial/ethnic variation in clinical features of disease and potential disparities in care, which may affect ADPKD outcomes.

A Systematic Review of Reported Outcomes in ADPKD Studies

Introduction

Methods

Results

Conclusion

Multidisciplinary management of chronic refractory pain in autosomal dominant polycystic kidney disease

BACKGROUND

Chronic pain is often difficult to manage in autosomal dominant polycystic kidney disease (ADPKD) patients and sometimes even leads to nephrectomy. We analyzed the long-term efficacy of our innovative multidisciplinary protocol to treat chronic refractory pain that aims to preserve kidney function by applying among other sequential nerve blocks.

METHODS

Patients were eligible if pain was present ≥3 months with a score of ≥50 on a visual analog scale (VAS) of 100, was negatively affecting quality of life and if there had been insufficient response to previous therapies, including opioid treatment. Treatment options were, in order, analgesics, cyst aspiration and fenestration, nerve blocks and nephrectomy.

RESULTS

A total of 101 patients were assessed in our clinic (mean age 50 ± 11 years, 65.3% females). Eight patients were treated with medication, 6 by cyst aspiration or fenestration, 63 by nerve blocks and 6 received surgery as the first treatment option. Overall, 76.9% experienced a positive effect on pain complaints shortly after treatment. The VAS score was reduced from 60/100 to 20/100 (P < 0.001) and patients decreased their number of nonopioid and opioid analgesics significantly (P < 0.001, P = 0.01, respectively). A substantial number of the patients (n = 51) needed additional treatment. At the end of follow-up in only 13 patients (12.9%) was surgical intervention necessary: 11 nephrectomies (of which 10 were in patients already on kidney function replacement treatment), 1 liver transplantation and 1 partial hepatectomy. After a median follow-up of 4.5 years (interquartile range 2.5-5.3), 69.0% of the patients still had fewer pain complaints.

CONCLUSIONS

These data indicate that our multidisciplinary treatment protocol appears effective in reducing pain in the majority of patients with chronic refractory pain, while postponing or even avoiding in most patients surgical interventions such as nephrectomy in most patients.

An update on the use of tolvaptan for ADPKD: Consensus statement on behalf of the ERA Working Group on Inherited Kidney Disorders (WGIKD), the European Rare Kidney Disease Reference Network (ERKNet) and Polycystic Kidney Disease International (PKD-International)

Approval of the vasopressin V2 receptor antagonist tolvaptan—based on the landmark TEMPO 3:4 trial—marked a transformation in the management of autosomal dominant polycystic kidney disease (ADPKD). This development has advanced patient care in ADPKD from general measures to prevent progression of chronic kidney disease to targeting disease-specific mechanisms. However, considering the long-term nature of this treatment, as well as potential side effects, evidence-based approaches to initiate treatment only in patients with rapidly progressing disease are crucial. In 2016, the position statement issued by the European Renal Association (ERA) was the first society-based recommendation on the use of tolvaptan and has served as a widely used decision-making tool for nephrologists. Since then, considerable practical experience regarding the use of tolvaptan in ADPKD has accumulated. More importantly, additional data from REPRISE, a second randomized clinical trial (RCT) examining the use of tolvaptan in later-stage disease, have added important evidence to the field, as have post hoc studies of these RCTs. To incorporate this new knowledge, we provide an updated algorithm to guide patient selection for treatment with tolvaptan and add practical advice for its use.

Developing a patient-centred tool for pain measurement and evaluation in autosomal dominant polycystic kidney disease

BACKGROUND

Pain affects 60% of the autosomal dominant polycystic kidney disease (ADPKD) population. Despite being an early and debilitating symptom, it is poorly characterized and management is suboptimal. This study aimed to develop an ADPKD-specific pain assessment tool (APAT) to facilitate pain research.

METHODS

Following a systematic review of PATs used in ADPKD studies and against international recommendations for pain trials, our multi-disciplinary team of clinical experts and patients constructed an ADPKD-pain conceptual framework of key pain evaluation themes. We compiled a new APAT covering domains prioritized within our framework using components of questionnaires validated in other chronic pain disorders. The APAT was administered longitudinally within a randomized high-water intake trial (NCT02933268) to ascertain feasibility and provide pilot data on ADPKD pain.

RESULTS

Thirty-nine ADPKD participants with chronic kidney disease Stages 1-4 provided 129 APAT responses. Each participant completed a median of 3 (range 1-10) assessments. Respondents' mean ± standard deviation age was 47 ± 13 years; 59% (23) were female; and 69% (27) had enlarged kidneys with median time from diagnosis 14.2 (interquartile range 7.0-25.9) years. Pain (52%) and associated analgesic use (29%) were common. Pain severity was associated with increasing age [odds ratio (OR) = 1.07, P = 0.009], female gender (OR = 4.34, P = 0.018), estimated glomerular filtration rate <60 mL/min/1.73 m2 (OR = 5.45, P = 0.021) and hypertension (OR = 12.11, P = 0.007), but not with kidney size (P = 0.23). The APAT achieved good internal consistency (Cronbach's alpha coefficient = 0.91) and test-retest reliability (domain intra-class correlation coefficients ranging from 0.62 to 0.90).

CONCLUSIONS

The APAT demonstrated good acceptability and reliability, and following further validation in a larger cohort could represent an invaluable tool for future ADPKD pain studies.

Insights Into the Molecular Mechanisms of Polycystic Kidney Diseases

Autosomal dominant (AD) and autosomal recessive (AR) polycystic kidney diseases (PKD) are severe multisystem genetic disorders characterized with formation and uncontrolled growth of fluid-filled cysts in the kidney, the spread of which eventually leads to the loss of renal function. Currently, there are no treatments for ARPKD, and tolvaptan is the only FDA-approved drug that alleviates the symptoms of ADPKD. However, tolvaptan has only a modest effect on disease progression, and its long-term use is associated with many side effects. Therefore, there is still a pressing need to better understand the fundamental mechanisms behind PKD development. This review highlights current knowledge about the fundamental aspects of PKD development (with a focus on ADPKD) including the PC1/PC2 pathways and cilia-associated mechanisms, major molecular cascades related to metabolism, mitochondrial bioenergetics, and systemic responses (hormonal status, levels of growth factors, immune system, and microbiome) that affect its progression. In addition, we discuss new information regarding non-pharmacological therapies, such as dietary restrictions, which can potentially alleviate PKD.

Effectiveness of Tolvaptan in the Treatment for Patients with Autosomal Dominant Polycystic Kidney Disease: A Meta-analysis

AIMS AND OBJECTIVE

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common chronic kidney disease that leads to End-Stage Renal Disease (ESRD). The key target of this therapy is to prevent the progression of kidney failure. Tolvaptan could slow kidney cyst growth and are proven highly effective. The aims of this analysis are to perform a systematic review, estimate and evaluate the efficacy and safety of tolvaptan in ADPKD patients.

MATERIALS AND METHODS

Randomized controlled trials of tolvaptan in ADPKD were identified in PubMed, Ovid, Web of Science and the Cochrane Library electronic database. The changes observed in kidney function, treatment efficiency and the incidence of adverse events between the tolvaptan and placebo groups were compared. Data were analyzed by the RevMan software.

RESULTS

Eight trials, including 7 double-blinded randomised controlled trials and 1 quasi RCT involving 1,536 patients were extracted. Significant differences in the annual rate of change in the total kidney volume TKV at any stages of CKD (MD = -3.32, 95%CI =-4.57,-2.07, I2 =70%) and the glomerular filtration rate (MD = 1.4, 95%CI = 0.83,1.97, I2 =0%) were observed between the tolvaptan group and the placebo group. Subgroup analysis of patients in different CKD stages also showed the same conclusion. There was an increase in the urine osmolality, and 24-hour urine volume in patients receiving tolvaptan. Tolvaptan reduced the rate of serious hypertension and kidney pain events in ADPKD patients. At higher doses, it increased the rate of adverse events (liver injuries, thirst, pollakiuria, and nocturia). There was no significant risk of bias in the included studies.

CONCLUSION

Tolvaptan has a beneficial effect on ADPKD, but is associated with an increase in adverse events at high doses when compared with the placebo. Further RCTs on tolvaptan may be required to support this conclusion.

Limitations and opportunities in the pharmacotherapy of ciliopathies

Ciliopathies are a family of rather diverse conditions, which have been grouped based on the finding of altered or dysfunctional cilia, potentially motile, small cellular antennae extending from the surface of postmitotic cells. Cilia-related disorders include embryonically arising conditions such as Joubert, Usher or Kartagener syndrome, but also afflictions with a postnatal or even adult onset phenotype, i.e. autosomal dominant polycystic kidney disease. The majority of ciliopathies are syndromic rather than affecting only a single organ due to cilia being found on almost any cell in the human body. Overall ciliopathies are considered rare diseases. Despite that, pharmacological research and the strive to help these patients has led to enormous therapeutic advances in the last decade. In this review we discuss new treatment options for certain ciliopathies, give an outlook on promising future therapeutic strategies, but also highlight the limitations in the development of therapeutic approaches of ciliopathies.

Characteristics of Patients with End-Stage Kidney Disease in ADPKD

Introduction

Cystic expansion damaging the parenchyma is thought to lead to end-stage kidney disease (ESKD) in autosomal dominant polycystic kidney disease (ADPKD). Here we characterized genotypic and phenotypic attributes of ADPKD at time of ESKD.

Methods

This is a retrospective cross-sectional study of patients with ADPKD with ESKD evaluated at Mayo Clinic with available abdominal computed tomography (CT) or magnetic resonance imaging (MRI). Kidney volumes were measured (total kidney volume adjusted for height [HtTKV]), Mayo Image Class (MIC) calculated, ADPKD genotype determined, and clinical and laboratory features obtained from medical records.

Results

Differences in HtTKV at ESKD were associated with patient age and sex; older patients and women had smaller HtTKV at ESKD. HtTKV at ESKD was observed to be 12.3% smaller with each decade of age (P < 0.01); but significant only in women (17.8%, P < 0.01; men 6.9%, P = 0.06). Patients with onset of ESKD at <47, 47–61, or >61 years had different characteristics, with a shift from youngest to oldest in male to female enrichment, MIC from 1D/1E to 1B/1C, likely fully penetrant PKD1 mutations from 95% to 42%, and presence of macrovascular disease from 8% to 40%. Macrovascular disease was associated with smaller kidneys in female patients.

Conclusion

HtTKV at ESKD was smaller with advancing age in patients with ADPKD, particularly in women. These novel findings provide insight into possible underlying mechanisms leading to ESKD, which differ between younger and older individuals. Cystic growth is the predominant mechanism in younger patients with ESKD, whereas aging-related factors, including vascular disease, becomes potentially important as patients age.

Urinary Lithogenic Risk Profile in ADPKD Patients Treated with Tolvaptan

BACKGROUND AND OBJECTIVES

Nephrolithiasis is a common health problem in autosomal dominant polycystic kidney disease (ADPKD) and significantly contributes to patient morbidity. Recently, Tolvaptan has been introduced for the treatment of ADPKD, but whether it is associated with alterations of the urinary lithogenic risk profile remains unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted an analysis of participants enrolled in the Bern ADPKD registry, a prospective observational cohort study. Twenty-four-hour urine analyses were performed at baseline and then at yearly follow-ups. Relative supersaturation ratios for calcium oxalate, brushite, and uric acid were calculated with the program EQUIL2. Unadjusted and multivariable mixed-effects linear regression models, adjusted for age, sex, body mass index, eGFR, net acid excretion, and height-adjusted total kidney volume, were used to assess the association of Tolvaptan with urinary parameters relevant for kidney stone formation. The maximum individual follow-up time was 3 years, median follow-up time 1.9 years, and cumulative follow-up time 169 years.

RESULTS

In total, 125 participants (38 with and 87 without Tolvaptan treatment) were included in the analysis. In multivariable analysis, Tolvaptan treatment was associated [adjusted estimate of the difference between Tolvaptan and no Tolvaptan; 95% confidence interval (CI)] with lower urine relative supersaturation ratios for calcium oxalate (-0.56; 95% CI, -0.82 to -0.3; P<0.001), brushite (-0.33; 95% CI, -0.54 to -0.11; P=0.004), and uric acid (-0.62; 95% CI, -0.88 to -0.37; P<0.001), and with higher urine citrate in mmol/mmol creatinine per day (0.25; 95% CI, 0.05 to 0.46; P=0.02) and calcium in mmol/mmol creatinine per day (0.31; 95% CI, 0.09 to 0.53; P=0.006) excretion. In addition, Tolvaptan treatment was associated with lower net acid excretion in mEq/mmol creatinine per day (-0.54; 95% CI, -0.90 to -0.17; P=0.004) and higher net gastrointestinal alkali absorption in mEq/mmol creatinine per day (0.57; 95% CI, 0.26 to 0.88; P<0.001).

CONCLUSIONS

Tolvaptan treatment is associated with a significantly improved urinary lithogenic risk profile in patients with ADPKD.

[Application of immunosuppressants in patients with autosomal dominant polycystic kidney disease after kidney transplantation]

OBJECTIVE

To investigate the optimal dose range of immunosuppressants in patients with autosomal dominant polycystic kidney disease (ADPKD) after renal transplantation.

METHODS

A cohort of 68 patients with ADPKD who received their first renal transplantation between March, 2000 and January, 2018 in our institute were retrospectively analyzed, with 68 non-ADPKD renal transplant recipients matched for gender, age and date of transplant as the control group. We analyzed the differences in patient and renal survival rates, postoperative complications and concentrations of immunosuppressive agents between the two groups at different time points within 1 year after kidney transplantation. The concentrations of the immunosuppressants were also compared between the ADPKD patients with urinary tract infections (UTI) and those without UTI after the transplantation.

RESULTS

The recipients with ADPKD and the control recipients showed no significantly difference in the overall 1-, 5-, and 10- year patient survival rates (96.6% vs 96.0%, 94.1% vs 93.9%, and 90.6% vs 93.9%, respectively; P > 0.05), 1-, 5-, and 10-year graft survival rates (95.2% vs 96.0%, 90.8% vs 87.2%, and 79.0% vs 82.3%, respectively; P > 0.05), or the incidences of other post- transplant complications including acute rejection, gastrointestinal symptoms, cardiovascular events, pneumonia, and neoplasms (P > 0.05). The plasma concentrations of both tacrolimus and mycophenolate mofetil (MPA) in ADPKD group were significantly lower than those in the control group at 9 months after operation (P < 0.05). The incidence of UTI was significantly higher in ADPKD patients than in the control group (P < 0.05). In patients with ADPKD, those with UTI after transplantation had a significantly higher MPA plasma concentration (P < 0.05).

CONCLUSIONS

In patients with ADPKD after renal transplant, a higher dose of MPA is associated with a increased risk of UTI, and their plasma concentrations of immunosuppressants for long-term maintenance of immunosuppression regimen can be lower than those in other kidney transplantation recipients.

Advances in Autosomal Dominant Polycystic Kidney Disease: A Clinical Review

Polycystic kidney disease (PKD) is a multiorgan disorder resulting in fluid-filled cyst formation in the kidneys and other systems. The replacement of kidney parenchyma with an ever-increasing volume of cysts eventually leads to kidney failure. Recently, increased understanding of the pathophysiology of PKD and genetic advances have led to new approaches of treatment targeting physiologic pathways, which has been proven to slow the progression of certain types of the disease. We review the pathophysiologic patterns and recent advances in the clinical pharmacotherapy of autosomal dominant PKD. A multipronged approach with pharmacologic and nonpharmacologic treatments can be successfully used to slow down the rate of progression of autosomal dominant PKD to kidney failure.

International consensus statement on the diagnosis and management of autosomal dominant polycystic kidney disease in children and young people

These recommendations were systematically developed on behalf of the Network for Early Onset Cystic Kidney Disease (NEOCYST) by an international group of experts in autosomal dominant polycystic kidney disease (ADPKD) from paediatric and adult nephrology, human genetics, paediatric radiology and ethics specialties together with patient representatives. They have been endorsed by the International Pediatric Nephrology Association (IPNA) and the European Society of Paediatric Nephrology (ESPN). For asymptomatic minors at risk of ADPKD, ongoing surveillance (repeated screening for treatable disease manifestations without diagnostic testing) or immediate diagnostic screening are equally valid clinical approaches. Ultrasonography is the current radiological method of choice for screening. Sonographic detection of one or more cysts in an at-risk child is highly suggestive of ADPKD, but a negative scan cannot rule out ADPKD in childhood. Genetic testing is recommended for infants with very-early-onset symptomatic disease and for children with a negative family history and progressive disease. Children with a positive family history and either confirmed or unknown disease status should be monitored for hypertension (preferably by ambulatory blood pressure monitoring) and albuminuria. Currently, vasopressin antagonists should not be offered routinely but off-label use can be considered in selected children. No consensus was reached on the use of statins, but mTOR inhibitors and somatostatin analogues are not recommended. Children with ADPKD should be strongly encouraged to achieve the low dietary salt intake that is recommended for all children.

Autosomal dominant polycystic kidney disease: updated perspectives

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited multisystem disorder, characterized by renal and extra-renal fluid-filled cyst formation and increased kidney volume that eventually leads to end-stage renal disease. ADPKD is considered the fourth leading cause of end-stage renal disease in the United States and globally. Care of patients with ADPKD was, for a long time, limited to supportive lifestyle measures, due to the lack of therapeutic strategies targeting the main pathways involved in the pathophysiology of ADPKD. As the first FDA approved treatment of ADPKD, Vasopressin (V2) receptor blocking agent, tolvaptan, is an urgently awaited advance for ADPKD patients. In our review, we also shed some lights on what is beyond Tolvaptan as there are other medications in the pipeline and many medications have been or are currently being studied in clinical trials such as Tesevatinib, Metformin and Pravastatin, with the goal of slowing the rate of progression of ADPKD by reducing the increase in total kidney volume or maintaining eGFR. Here, we review updates in the perspectives and management of ADPKD.

Modelling the long-term benefits of tolvaptan therapy on renal function decline in autosomal dominant polycystic kidney disease: an exploratory analysis using the ADPKD outcomes model

Background

The short-term efficacy of tolvaptan in patients with autosomal dominant polycystic kidney disease (ADPKD) has been demonstrated across several phase 3 trials, while the ADPKD Outcomes Model (ADPKD-OM) represents a validated approach to predict natural disease progression over a lifetime horizon. This study describes the implementation of a tolvaptan treatment effect within the ADPKD-OM and explores the potential long-term benefits of tolvaptan therapy in ADPKD.

Methods

The effect of tolvaptan on ADPKD progression was modelled by applying a constant treatment effect to the rate of renal function decline, consistent with that observed in the Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes trial (TEMPO 3:4; ClinicalTrials.gov identifier NCT00428948). Predictions generated by the ADPKD-OM were compared against aggregated data from a subsequent extension trial (TEMPO 4:4; ClinicalTrials.gov identifier NCT01214421) and the Replicating Evidence of Preserved Renal Function an Investigation of Tolvaptan Safety Efficacy in ADPKD trial (REPRISE; ClinicalTrials.gov identifier NCT02160145). Following validation, an application of the ADPKD-OM sought to estimate the benefit of tolvaptan therapy on time to end-stage renal disease (ESRD), in a range of ADPKD populations.

Results

Model validation against TEMPO 4:4 and REPRISE demonstrated the accuracy and generalisability of the tolvaptan treatment effect applied within the ADPKD-OM. In simulated patients matched to the overall TEMPO 3:4 trial population at baseline, tolvaptan therapy was predicted to delay the mean age of ESRD onset by five years, compared to natural disease progression (57 years versus 52 years, respectively). In subgroup and sensitivity analyses, the estimated delay to ESRD was greatest among patients with CKD stage 1 at baseline (6.6 years), compared to CKD 2 and 3 subgroups (4.7 and 2.7 years, respectively); and ADPKD patients in Mayo subclasses 1C–1E.

Conclusions

This study demonstrated the potential for tolvaptan therapy to delay time to ESRD, particularly among patients with early-stage CKD and evidence of rapidly progressing disease. Data arising from this study highlight the value to be gained by early intervention and long-term treatment with tolvaptan, which may alleviate the economic and societal costs of providing care to patients who progress to ESRD.

Impact of Recent Clinical Trials on Nephrology Practice: Are We in a Stagnant Era?

BACKGROUND

Although renal replacement therapy prevents death from uremia, survival among patients with acute and chronic kidney diseases (CKD) remains an imperative concern. The expected life span of US dialysis patients 60-64 years of age is approximately 4.5 years; this is similar to that of patients with lung cancer. Despite substantial progress in many medical specialties over the past decades (e.g., notable reductions in myocardial infarction, stroke, and mortality rates in the general population), survival among dialysis patients has not improved significantly over the same period. A few decades ago, HIV infection and AIDS were pretty much a death sentence. Because of progress in HIV treatment, now it can be controlled with a daily pill, and ongoing research is pushing treatment even further and controls the virus with longer-acting treatment. A cure is no longer impossible for HIV and other viral infections such as hepatitis B and C and many malignancies, but so far there is no cure for CKD.

SUMMARY

Billions of dollars have been spent on kidney disease research in the past decades, with no tangible progress in clinical practice. The challenges of improving the quantity and quality of trials in nephrology are enormous. The number of randomized controlled trials (RCTs) published in nephrology is lower than that in other medical subspecialties, and most of the big RCTs in nephrology yield negative results. Nephrology studies evaluating hard clinical endpoints or surrogate endpoints are scarce.

KEY MESSAGE

Herein we discuss the slow progress in nephrology research that has impacted clinical practice over the last couple of decades and highlight the major obstacles, challenges, and potential solutions.

Randomised controlled trial of high versus ad libitum water intake in patients with autosomal dominant polycystic kidney disease: rationale and design of the DRINK feasibility trial

INTRODUCTION

Vasopressin stimulates cyst growth in autosomal dominant polycystic kidney disease (ADPKD) leading to enlarged kidneys, hypertension and renal failure. Vasopressin receptor blockade slows disease progression. Physiological suppression of vasopressin secretion through high water (HW) intake could achieve a similar effect, necessitating a definitive large-scale trial of HW intake in ADPKD. The objective of the DRINK trial is to answer the key design and feasibility questions required to deliver a successful definitive water intake trial.

METHODS AND ANALYSIS

We describe the design of a single-centre, open-label, prospective, randomised controlled trial. The "Determining feasibility of R andomisation to high vs. ad libitum water In take in Polycystic K idney Disease" (DRINK) trial aims to enrol 50 patients with ADPKD, over the age of 16 years with an estimated glomerular filtration rate (eGFR) ≥20 mL/min/1.73 m². Participants will be randomised 1:1 to HW intake based on an individualised water intake prescription, or to ad libitum (AW) water intake. The HW group will aim for a dilute urine (urine osmolality ≤270 mOsm/kg) as a surrogate marker of vasopressin suppression, and those in the AW group will target more concentrated urine. Participants will have an 8-week treatment period, and will be seen at weeks 0, 2, 4 and 8, undergoing assessments of fluid status, renal function and serum and urine osmolalities. They will receive dietary advice, and self-monitor urine specific gravity and fluid intake. The trial employs smartphone technology to permit home monitoring and remote direct data capture. The primary feasibility end points are recruitment rate and separation between arms in measured urinary osmolality. Key secondary assessments include acceptability, adherence, health-related quality of life, acute effects of HW intake on measured (⁵¹Cr-EDTA) and eGFR and ADPKD-related pain.

ETHICS AND DISSEMINATION

Ethical approval was awarded by the East of England Essex Research Ethics Committee (16/EE/0026). The results of DRINK will be submitted to peer-reviewed journals, and presented to patients via the PKD Charity.

TRIAL REGISTRATION NUMBER

NCT02933268 and ISCRTN16794957.

Insights into cellular and molecular basis for urinary tract infection in autosomal-dominant polycystic kidney disease

Urinary tract infection (UTI) is a broad term referring to an infection of the kidneys, ureters, bladder, and/or urethra. Because of its prevalence, frequent recurrence, and rising resistance to antibiotics, UTI has become a challenge in clinical practice. Autosomal-dominant polycystic kidney disease (ADPKD) is the most common monogenic disorder of the kidney and is characterized by the growth of fluid-filled cysts in both kidneys. Progressive cystic enlargement, inflammation, and interstitial fibrosis result in nephron loss with subsequent decline in kidney function. ADPKD patients frequently develop UTI; however, the cellular and molecular mechanisms responsible for the high UTI incidence in ADPKD patients remain virtually unaddressed. Emerging evidence suggests that α-intercalated cells (α-ICs) of the collecting ducts function in the innate immune defense against UTI. α-ICs inhibit bacterial growth by acidifying urine and secreting neutrophil gelatinase-associated lipocalin (NGAL) that chelates siderophore-containing iron. It is necessary to determine, therefore, if ADPKD patients with recurrent UTI have a reduced number and/or impaired function of α-ICs. Identification of the underlying cellular and molecular mechanisms may lead to the development of novel strategies to reduce UTI in ADPKD.