Safety and efficacy of long-acting somatostatin treatment in autosomal-dominant polycystic kidney disease

Liver manifestations in autosomal dominant polycystic kidney disease (ADPKD) and their impact on quality of life

Background

ADPKD is the most prevalent monogenic kidney disease with an estimated incidence of 1:1000. The condition is characterized by the formation of kidney cysts, which can cause kidney function loss and bear a significant risk of advancing to kidney failure. This study examined the prevalence of hepatic cysts in individuals with ADPKD, and the possible influence of these cysts on liver function and quality of life. Furthermore, the relationship between hepatic cysts and genotype was analysed.

Methods

Clinical data from 880 patients with ADPKD were analysed, including longitudinal patient data, genetic information, and laboratory parameters.

Results

The prevalence of hepatic cysts in adult ADPKD patients was 81.71%, consistent with previous studies. Prevalence increased with age, particularly in male patients. No clear association was observed between ADPKD genotype and the presence of liver cysts. Among male patients with liver cysts, glutamate pyruvate transaminase (GPT) levels significantly decreased with age, while female patients showed a significant increase in gamma-glutamyl transferase (γ-GT) levels. Overall, hepatic cysts had minimal impact on liver enzymes. Quality of life assessments using the SF-12 questionnaire revealed no significant influence of hepatic cysts on physical or mental well-being. However, physical quality of life was significantly lower in patients showing polycystic liver disease as a manifestation of ADPKD compared to all other patients, both with and without liver cysts.

Conclusions

Hepatic cysts are highly prevalent in adult patients with ADPKD, increasing with age. ADPKD genotype does not appear to be associated with the presence of hepatic cysts. Liver function, as indicated by enzyme levels, is minimally affected by hepatic cysts in most ADPKD patients. The quality of life of ADPKD patients is generally unaffected by the presence of hepatic cysts, except in severe cases of polycystic liver disease (PLD). Further research is needed to develop effective treatments for severe PLD and gain a better understanding of the factors influencing hepatic cyst incidence and progression in patients with ADPKD.

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 screening, diagnosis, and management of patients with autosomal dominant polycystic kidney disease: A national consensus statement from Taiwan

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of end-stage kidney disease (ESKD) worldwide. Guidelines for the diagnosis and management of ADPKD in Taiwan remains unavailable. In this consensus statement, we summarize updated information on clinical features of international and domestic patients with ADPKD, followed by suggestions for optimal diagnosis and care in Taiwan. Specifically, counselling for at-risk minors and reproductive issues can be important, including ethical dilemmas surrounding prenatal diagnosis and pre-implantation genetic diagnosis. Studies reveal that ADPKD typically remains asymptomatic until the fourth decade of life, with symptoms resulting from cystic expansion with visceral compression, or rupture. The diagnosis can be made based on a detailed family history, followed by imaging studies (ultrasound, computed tomography, or magnetic resonance imaging). Genetic testing is reserved for atypical cases mostly. Common tools for prognosis prediction include total kidney volume, Mayo classification and PROPKD/genetic score. Screening and management of complications such as hypertension, proteinuria, urological infections, intracranial aneurysms, are also crucial for improving outcome. We suggest that the optimal management strategies of patients with ADPKD include general medical care, dietary recommendations and ADPKD-specific treatments. Key points include rigorous blood pressure control, dietary sodium restriction and Tolvaptan use, whereas the evidence for somatostatin analogues and mammalian target of rapamycin (mTOR) inhibitors remains limited. In summary, we outline an individualized care plan emphasizing careful monitoring of disease progression and highlight the need for shared decision-making among these patients.

Clinical findings, underlying pathogenetic processes and treatment of vascular dysfunction in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited disorder characterized by the development of fluid-filled cysts in the kidneys. The primary cause of ADPKD is mutations in the PKD1 (polycystic kidney disease 1) or PKD2 (polycystic kidney disease 2) gene. Patients with ADPKD often develop a variety of vascular abnormalities, which have a major impact on the structure and function of the blood vessels and can lead to complications such as hypertension, intracranial aneurysm (ICAN), and atherosclerosis. The progression of ADPKD involves intricate molecular and cellular processes that lead to the development of these vascular abnormalities. Our understanding of these processes remains incomplete, and available treatment options are limited. The aim of this review is to delve into the underlying mechanisms of these vascular abnormalities and to explore potential interventions.

Enteroendocrine cells and gut hormones as potential targets in the crossroad of the gut-kidney axis communication

Recent studies suggest that disruptions in intestinal homeostasis, such as changes in gut microbiota composition, infection, and inflammatory-related gut diseases, can be associated with kidney diseases. For instance, genomic investigations highlight how susceptibility genes linked to IgA nephropathy are also correlated with the risk of inflammatory bowel disease. Conversely, investigations demonstrate that the use of short-chain fatty acids, produced through fermentation by intestinal bacteria, protects kidney function in models of acute and chronic kidney diseases. Thus, the dialogue between the gut and kidney seems to be crucial in maintaining their proper function, although the factors governing this crosstalk are still emerging as the field evolves. In recent years, a series of studies have highlighted the significance of enteroendocrine cells (EECs) which are part of the secretory lineage of the gut epithelial cells, as important components in gut-kidney crosstalk. EECs are distributed throughout the epithelial layer and release more than 20 hormones in response to microenvironment stimuli. Interestingly, some of these hormones and/or their pathways such as Glucagon-Like Peptide 1 (GLP-1), GLP-2, gastrin, and somatostatin have been shown to exert renoprotective effects. Therefore, the present review explores the role of EECs and their hormones as regulators of gut-kidney crosstalk and their potential impact on kidney diseases. This comprehensive exploration underscores the substantial contribution of EEC hormones in mediating gut-kidney communication and their promising potential for the treatment of kidney diseases.

Repurposing small molecules for Nephronophthisis and related renal ciliopathies

Nephronophthisis is an autosomal recessive tubulo-interstitial nephropathy, belonging to the ciliopathy disorders, characterized by fibrosis and/or cysts. It is the most common genetic cause of renal failure in children and young adults. Clinically and genetically heterogeneous, it is caused by variants in ciliary genes resulting in either an isolated kidney disease or syndromic forms in association with other manifestations of ciliopathy disorders. No curative treatment is currently available. Over the past two decades, advances in understanding disease mechanisms have identified several dysregulated signaling pathways, some shared with other cystic kidney diseases. Notably, molecules previously developed to target these pathways have shown promising beneficial effects in orthologous mouse models. In addition to these knowledge-based repurposing approaches, unbiased "in cellulo" phenotypic screens of "repurposing" libraries identified small molecules able to rescue the ciliogenesis defects observed in nephronophthisis conditions. Those compounds appeared to act on relevant pathways and, when tested, showed beneficial nephronophthisis-associated kidney and/or extra-renal defects in mice. In this review, we have summarized those studies which highlight the drug repurposing strategies in the context of a rare disorders such as nephronophthisis-related ciliopathies, with broad genetic heterogeneity and systemic manifestations but with shared disease mechanisms.

Drug repurposing in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease is characterized by progressive kidney cyst formation that leads to kidney failure. Tolvaptan, a vasopressin 2 receptor antagonist, is the only drug approved to treat patients with autosomal dominant polycystic kidney disease who have rapid disease progression. The use of tolvaptan is limited by reduced tolerability from aquaretic effects and potential hepatotoxicity. Thus, the search for more effective drugs to slow down the progression of autosomal dominant polycystic kidney disease is urgent and challenging. Drug repurposing is a strategy for identifying new clinical indications for approved or investigational medications. Drug repurposing is increasingly becoming an attractive proposition because of its cost-efficiency and time-efficiency and known pharmacokinetic and safety profiles. In this review, we focus on the repurposing approaches to identify suitable drug candidates to treat autosomal dominant polycystic kidney disease and prioritization and implementation of candidates with high probability of success. Identification of drug candidates through understanding of disease pathogenesis and signaling pathways is highlighted.

Effects of Octreotide-Long-Acting Release Added-on Tolvaptan in Patients with Autosomal Dominant Polycystic Kidney Disease: Pilot, Randomized, Placebo-Controlled, Cross-Over Trial

BACKGROUND

Tolvaptan and octreotide-long-acting release (LAR) have renoprotective effects in autosomal dominant polycystic kidney disease (ADPKD) that are partially mediated by amelioration of compensatory glomerular hyperfiltration. We compared the effects of tolvaptan and octreotide-LAR combination therapy versus those of tolvaptan monotherapy in patients with ADPKD.

METHODS

This pilot, randomized, placebo-controlled, cross-over trial primarily compared the effects of 1- and 4-week treatments with octreotide-LAR (two 20-mg i.m. injections) or placebo (two i.m. 0.9% saline solution injections) added-on tolvaptan (up to 90 and 30 mg/d) on GFR (iohexol plasma clearance) in 19 consenting patients with ADPKD referred to a clinical research center in Italy. Analyses were intention-to-treat. The local ethical committee approved the study.

RESULTS

At 4 weeks, GFR significantly decreased by a median (interquartile range) of 3 (-1 to 5) ml/min per 1.73 m2 with tolvaptan and placebo (P=0.01) and by 7 (3-14) ml/min per 1.73 m2 with tolvaptan and octreotide-LAR (P=0.03). GFR changes during the two treatment periods differed by 2 (-5 to 14) ml/min per 1.73 m2 (P=0.28). At 1 week, GFR significantly decreased by 3 (0-7) ml/min per 1.73 m2 with tolvaptan and placebo (P=0.006) and by 10 (-6 to 16) ml/min per 1.73 m2 with tolvaptan and octreotide-LAR add-on therapy (P<0.001). GFR changes during the two treatment periods significantly differed by 3 (0-12) ml/min per 1.73 m2 (P=0.012). Total kidney volume nonsignificantly changed by 4 (-48 to 23) ml with tolvaptan and placebo (P=0.74), whereas it decreased significantly by 41 (25-77) ml with tolvaptan and octreotide-LAR (P=0.001). Changes during the two treatment periods differed by 36 (0-65) ml (P=0.01). Octreotide-LAR also attenuated (P=0.02) the aquaretic effect of tolvaptan. Treatments were well tolerated.

CONCLUSIONS

In patients with ADPKD, octreotide-LAR added-on tolvaptan reduced GFR more effectively than octreotide-LAR and placebo. Octreotide-LAR also reduced total and cystic kidney volumes and attenuated the acquaretic effect of tolvaptan.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Tolvaptan-Octreotide LAR Combination in ADPKD (TOOL), NCT03541447.

A Systematic Review of Reported Outcomes in ADPKD Studies

Introduction

Methods

Results

Conclusion

Genetics, pathobiology and therapeutic opportunities of polycystic liver disease

Polycystic liver diseases (PLDs) are inherited genetic disorders characterized by progressive development of intrahepatic, fluid-filled biliary cysts (more than ten), which constitute the main cause of morbidity and markedly affect the quality of life. Liver cysts arise in patients with autosomal dominant PLD (ADPLD) or in co-occurrence with renal cysts in patients with autosomal dominant or autosomal recessive polycystic kidney disease (ADPKD and ARPKD, respectively). Hepatic cystogenesis is a heterogeneous process, with several risk factors increasing the odds of developing larger cysts. Depending on the causative gene, PLDs can arise exclusively in the liver or in parallel with renal cysts. Current therapeutic strategies, mainly based on surgical procedures and/or chronic administration of somatostatin analogues, show modest benefits, with liver transplantation as the only potentially curative option. Increasing research has shed light on the genetic landscape of PLDs and consequent cholangiocyte abnormalities, which can pave the way for discovering new targets for therapy and the design of novel potential treatments for patients. Herein, we provide a critical and comprehensive overview of the latest advances in the field of PLDs, mainly focusing on genetics, pathobiology, risk factors and next-generation therapeutic strategies, highlighting future directions in basic, translational and clinical research.

Comparative Efficacy of Pharmacological Treatments for Adults With Autosomal Dominant Polycystic Kidney Disease: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Background: Tolvaptan is the gold standard treatment for autosomal dominant polycystic kidney disease (ADPKD), while several other drugs have the potential to inhibit the progression of ADPKD. However, individual clinical trials may not show sufficient differences in clinical efficacy due to small sample sizes. Furthermore, the differences in therapeutic efficacy among drugs are unclear. Herein, we investigated the effect of the ADPKD treatments. Methods: We systematically searched PubMed, Medline, EMBASE, and the Cochrane Library through January 2022 to identify randomized controlled trials in ADPKD patients that compared the effects of treatments with placebo or conventional therapy. A network meta-analysis was performed to compare the treatments indirectly. The primary outcomes were changes in kidney function and the rate of total kidney volume (TKV) growth. Results: Sixteen studies were selected with a total of 4,391 patients. Tolvaptan significantly preserved kidney function and inhibited TKV growth compared to the placebo {standardized mean difference (SMD) [95% confidence interval (CI)]: 0.24 (0.16; 0.31) and MD: -2.70 (-3.10; -2.30), respectively}. Tyrosine kinase inhibitors and mammalian target of rapamycin (mTOR) inhibitors inhibited TKV growth compared to the placebo; somatostatin analogs significantly inhibited TKV growth compared to the placebo and tolvaptan [MD: -5.69 (-7.34; -4.03) and MD: -2.99 (-4.69; -1.29), respectively]. Metformin tended to preserve renal function, although it was not significant [SMD: 0.28 (-0.05; 0.61), p = 0.09]. Conclusion: The therapeutic effect of tolvaptan was reasonable as the gold standard for ADPKD treatment, while somatostatin analogs also showed notable efficacy in inhibiting TKV growth. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42022300814.

A Shared Nephroprotective Mechanism for Renin-Angiotensin-System Inhibitors, Sodium-Glucose Co-Transporter 2 Inhibitors, and Vasopressin Receptor Antagonists: Immunology Meets Hemodynamics

A major paradigm in nephrology states that the loss of filtration function over a long time is driven by a persistent hyperfiltration state of surviving nephrons. This hyperfiltration may derive from circulating immunological factors. However, some clue about the hemodynamic effects of these factors derives from the effects of so-called nephroprotective drugs. Thirty years after the introduction of Renin-Angiotensin-system inhibitors (RASi) into clinical practice, two new families of nephroprotective drugs have been identified: the sodium-glucose cotransporter 2 inhibitors (SGLT2i) and the vasopressin receptor antagonists (VRA). Even though the molecular targets of the three-drug classes are very different, they share the reduction in the glomerular filtration rate (GFR) at the beginning of the therapy, which is usually considered an adverse effect. Therefore, we hypothesize that acute GFR decline is a prerequisite to obtaining nephroprotection with all these drugs. In this study, we reanalyze evidence that RASi, SGLT2i, and VRA reduce the eGFR at the onset of therapy. Afterward, we evaluate whether the extent of eGFR reduction correlates with their long-term efficacy. The results suggest that the extent of initial eGFR decline predicts the nephroprotective efficacy in the long run. Therefore, we propose that RASi, SGLT2i, and VRA delay kidney disease progression by controlling maladaptive glomerular hyperfiltration resulting from circulating immunological factors. Further studies are needed to verify their combined effects.

Autosomal Dominant Polycystic Kidney Disease: From Pathophysiology of Cystogenesis to Advances in the Treatment

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic renal disease, with an estimated prevalence between 1:1000 and 1:2500. It is mostly caused by mutations of the PKD1 and PKD2 genes encoding polycystin 1 (PC1) and polycystin 2 (PC2) that regulate cellular processes such as fluid transport, differentiation, proliferation, apoptosis and cell adhesion. Reduction of calcium ions and induction of cyclic adenosine monophosphate (sAMP) promote cyst enlargement by transepithelial fluid secretion and cell proliferation. Abnormal activation of MAPK/ERK pathway, dysregulated signaling of heterotrimeric G proteins, mTOR, phosphoinositide 3-kinase, AMPK, JAK/STAT activator of transcription and nuclear factor kB (NF-kB) are involved in cystogenesis. Another feature of cystic tissue is increased extracellular production and recruitment of inflammatory cells and abnormal connections among cells. Moreover, metabolic alterations in cystic cells including defective glucose metabolism, impaired beta-oxidation and abnormal mitochondrial activity were shown to be associated with cyst expansion. Although tolvaptan has been recently approved as a drug that slows ADPKD progression, some patients do not tolerate tolvaptan because of frequent aquaretic. The advances in the knowledge of multiple molecular pathways involved in cystogenesis led to the development of animal and cellular studies, followed by the development of several ongoing randomized controlled trials with promising drugs. Our review is aimed at pathophysiological mechanisms in cystogenesis in connection with the most promising drugs in animal and clinical studies.

Retarding Progression of Chronic Kidney Disease in Autosomal Dominant Polycystic Kidney Disease with Metformin and Other Therapies: An Update of New Insights

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent single-gene disorder leading to renal failure. Current therapies are aimed to treat renal and extrarenal complications of ADPKD, but improved knowledge of the pathophysiological mechanisms leading to the generation and growth of cysts has permitted the identification of new drug candidates for clinical trials. Among these, in this review, we will examine above all the role of metformin, hypothesized to be able to activate the AMP-activated protein kinase (AMPK) pathway and potentially modulate some mechanisms implicated in the onset and the growth of the cysts.

Somatostatin analog therapy effectiveness on the progression of polycystic kidney and liver disease: A systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Uncertainty underlies the effectiveness of somatostatin analogues for slowing the progression of polycystic kidney or liver disease.

METHODS

Eligible studies included randomized controlled trials (RCTs) evaluating somatostatin analog as therapy for patients with polycystic kidney disease (PKD) or polycystic liver disease (PLD) compared to placebo or standard therapy. Two reviewers independently screened studies identified from databases (MEDLINE, EMBASE, Cochrane Database), clinical trial registries, and references from pertinent articles and clinical practice guidelines. Outcome measurements were changes in total liver volume (TLV), total kidney volume (TKV), and estimated glomerular filtration rate (eGFR).

RESULTS

Of 264 nonduplicate studies screened, 10 RCTs met the inclusion criteria. The body of evidence provided estimates warranting moderate confidence. Meta-analysis of 7 RCTs including a total of 652 patients showed that somatostatin analogs are associated with a lower %TLV growth rate compared to control (mean difference, -6.37%; 95% CI -7.90 to -4.84, p<0.00001), and with a lower %TKV growth rate compared to control (mean difference, -3.66%; 95% CI -5.35 to -1.97, p<0.0001). However, it was not associated with a difference in eGFR decline (mean difference, -0.96 mL/min./1.73m2; 95% CI -2.38 to 0.46, p = 0.19).

CONCLUSIONS

Current body of evidence suggests that somatostatin analogs therapy slows the increase rate of TLV and TKV in patients with PKD or PLD compared to control within a 3-year follow-up period. It does not seem to have an effect on the change in eGFR. Somatostatin analogs therapy can be a promising treatment for ADPKD or ADPLD, and we need to continue to research its effectiveness for ADPKD or ADPLD.

The cellular pathways and potential therapeutics of Polycystic Kidney Disease

Polycystic Kidney Disease (PKD) refers to a group of disorders, driven by the formation of cysts in renal tubular cells and is currently one of the leading causes of end-stage renal disease. The range of symptoms observed in PKD is due to mutations in cilia-localising genes, resulting in changes in cellular signalling. As such, compounds that are currently in preclinical and clinical trials target some of these signalling pathways that are dysregulated in PKD. In this review, we highlight these pathways including cAMP, EGF and AMPK signalling and drugs that target them and may show promise in lessening the disease burden of PKD patients. At present, tolvaptan is the only approved therapy for ADPKD, however, it carries several adverse side effects whilst comparatively, no pharmacological drug is approved for ARPKD treatment. Aside from this, drugs that have been the subject of multiple clinical trials such as metformin, which targets AMPK signalling and somatostatins, which target cAMP signalling have shown great promise in reducing cyst formation and cellular proliferation. This review also discusses other potential and novel targets that can be used for future interventions, such as β-catenin and TAZ, where research has shown that a reduction in the overexpression of these signalling components results in amelioration of disease phenotype. Thus, it becomes apparent that well-designed preclinical investigations and future clinical trials into these pathways and other potential signalling targets are crucial in bettering disease prognosis for PKD patients and could lead to personalised therapy approaches.

Renal Ciliopathies: Sorting Out Therapeutic Approaches for Nephronophthisis

Nephronophthisis (NPH) is an autosomal recessive ciliopathy and a major cause of end-stage renal disease in children. The main forms, juvenile and adult NPH, are characterized by tubulointerstitial fibrosis whereas the infantile form is more severe and characterized by cysts. NPH is caused by mutations in over 20 different genes, most of which encode components of the primary cilium, an organelle in which important cellular signaling pathways converge. Ciliary signal transduction plays a critical role in kidney development and tissue homeostasis, and disruption of ciliary signaling has been associated with cyst formation, epithelial cell dedifferentiation and kidney function decline. Drugs have been identified that target specific signaling pathways (for example cAMP/PKA, Hedgehog, and mTOR pathways) and rescue NPH phenotypes in in vitro and/or in vivo models. Despite identification of numerous candidate drugs in rodent models, there has been a lack of clinical trials and there is currently no therapy that halts disease progression in NPH patients. This review covers the most important findings of therapeutic approaches in NPH model systems to date, including hypothesis-driven therapies and untargeted drug screens, approached from the pathophysiology of NPH. Importantly, most animal models used in these studies represent the cystic infantile form of NPH, which is less prevalent than the juvenile form. It appears therefore important to develop new models relevant for juvenile/adult NPH. Alternative non-orthologous animal models and developments in patient-based in vitro model systems are discussed, as well as future directions in personalized therapy for NPH.

Acromegaly accompanied by diabetes mellitus and polycystic kidney disease

Acromegaly is characterized by autonomous excessive growth hormone (GH) secretion, generally due to GH-producing pituitary adenoma, and is associated with various systemic comorbidities including diabetes mellitus. Polycystic kidney disease (PKD) is characterized by the growth of numerous cysts in the kidneys that deteriorate renal function. While possible renal effects of excessive GH exposure have been a current issue in experimental medicine, only five cases of coexisting acromegaly and PKD have been reported previously, and little is known regarding the influence of acromegaly on renal disease. We treated a 50-year-old male with diabetes mellitus who showed a sudden and rapid decline of renal function along with increasing proteinuria, which led to diagnoses of PKD and acromegaly. His urinary protein levels were increased together with excessive GH secretion and worsening glycemic control. An increase of total kidney volume was also noted. Transsphenoidal surgery for the pituitary adenoma was successfully performed. Marked improvement of hyperglycemia and proteinuria were observed after the surgery, but renal function was unchanged. The patient's clinical course suggested common aspects of excessive GH secretion as an accelerating factor of the progression of diabetic nephropathy and PKD via direct and indirect pathways. Although coexisting acromegaly and PKD is clinically rare, vigilance for early diagnosis of acromegaly is appropriate in patients with diabetes and/or PKD, especially in those showing unexpected exacerbation of renal dysfunction.

A randomized phase 1b cross-over study of the safety of low-dose pioglitazone for treatment of autosomal dominant polycystic kidney disease

Background

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common monogenetic disorders in humans and is characterized by numerous fluid-filled cysts that grow slowly, resulting in end-stage renal disease in the majority of patients. Preclinical studies have indicated that treatment with low-dose thiazolidinediones, such as pioglitazone, decrease cyst growth in rodent models of PKD.

Methods

This Phase 1b cross-over study compared the safety of treatment with a low dose (15 mg) of the peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist pioglitazone or placebo in PKD patients, with each treatment given for 1 year. The study monitored known side effects of PPAR-γ agonist treatment, including fluid retention and edema. Liver enzymes and risk of hypoglycemia were assessed throughout the study. As a secondary objective, the efficacy of low-dose pioglitazone was followed using a primary assessment of total kidney volume (TKV), blood pressure (BP) and kidney function.

Results

Eighteen patients were randomized and 15 completed both arms. Compared with placebo, allocation to pioglitazone resulted in a significant decrease in total body water as assessed by bioimpedance analysis {mean difference 0.16 Ω [95% confidence interval (CI) 0.24–2.96], P = 0.024} and no differences in episodes of heart failure, clinical edema or change in echocardiography. Allocation to pioglitazone led to no difference in the percent change in TKV of −3.5% (95% CI −8.4–1.4, P = 0.14), diastolic BP and microalbumin:creatinine ratio.

Conclusions

In this small pilot trial in people with ADPKD but without diabetes, pioglitazone 15 mg was found to be as safe as placebo. Larger and longer-term randomized trials powered to assess effects on TKV are needed.

Somatostatin in renal physiology and autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst formation, leading to growth in kidney volume and renal function decline. Although therapies have emerged, there is still an important unmet need for slowing the rate of disease progression in ADPKD. High intracellular levels of adenosine 3′,5′-cyclic monophosphate (cAMP) are involved in cell proliferation and fluid secretion, resulting in cyst formation. Somatostatin (SST), a hormone that is involved in many cell processes, has the ability to inhibit intracellular cAMP production. However, SST itself has limited therapeutic potential since it is rapidly eliminated in vivo. Therefore analogues have been synthesized, which have a longer half-life and may be promising agents in the treatment of ADPKD. This review provides an overview of the complex physiological effects of SST, in particular renal, and the potential therapeutic role of SST analogues in ADPKD.

Targeting and therapeutic peptide-based strategies for polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by progressive cyst growth and is a leading cause of renal failure worldwide. Currently, there are limited therapeutic options available to PKD patients, and only one drug, tolvaptan, has been FDA-approved to slow cyst progression. Similar to other small molecule drugs, however, tolvaptan is costly, only moderately effective, and causes adverse events leading to high patient dropout rates. Peptides may mitigate many drawbacks of small molecule drugs, as they can be highly tissue-specific, biocompatible, and economically scaled-up. Peptides can function as targeting ligands that direct therapies to diseased renal tissue, or be potent as therapeutic agents themselves. This review discusses various aberrant signaling pathways in PKD and renal receptors that can be potential targets of peptide-mediated strategies. Additionally, peptides utilized in other kidney applications, but may prove useful in the context of PKD, are highlighted. Insights into novel peptide-based solutions that have potential to improve clinical management of PKD are provided.

Modulation of polycystic kidney disease by G-protein coupled receptors and cyclic AMP signaling

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic disorder associated with polycystic liver disease (PLD) and other extrarenal manifestations, the most common monogenic cause of end-stage kidney disease, and a major burden for public health. Many studies have shown that alterations in G-protein and cAMP signaling play a central role in its pathogenesis. As for many other diseases (35% of all approved drugs target G-protein coupled receptors (GPCRs) or proteins functioning upstream or downstream from GPCRs), treatments targeting GPCR have shown effectiveness in slowing the rate of progression of ADPKD. Tolvaptan, a vasopressin V2 receptor antagonist is the first drug approved by regulatory agencies to treat rapidly progressive ADPKD. Long-acting somatostatin analogs have also been effective in slowing the rates of growth of polycystic kidneys and liver. Although no treatment has so far been able to prevent the development or stop the progression of the disease, these encouraging advances point to G-protein and cAMP signaling as a promising avenue of investigation that may lead to more effective and safe treatments. This will require a better understanding of the relevant GPCRs, G-proteins, cAMP effectors, and of the enzymes and A-kinase anchoring proteins controlling the compartmentalization of cAMP signaling. The purpose of this review is to provide an overview of general GPCR signaling; the function of polycystin-1 (PC1) as a putative atypical adhesion GPCR (aGPCR); the roles of PC1, polycystin-2 (PC2) and the PC1-PC2 complex in the regulation of calcium and cAMP signaling; the cross-talk of calcium and cAMP signaling in PKD; and GPCRs, adenylyl cyclases, cyclic nucleotide phosphodiesterases, and protein kinase A as therapeutic targets in ADPKD.

Somatostatin Analogs in Clinical Practice: a Review

Somatostatin analogs are an invaluable therapeutic option in the diagnosis and treatment of somatotropinomas, thyrotropinomas, and functioning and non-functioning gastroenteropancreatic neuroendocrine tumors. They should also be considered an effective and safe therapeutic alternative to corticotropinomas, gonadotropinomas, and prolactinomas resistant to dopamine agonists. Somatostatin analogs have also shown to be useful in the treatment of other endocrine diseases (congenital hyperinsulinism, Graves’ orbitopathy, diabetic retinopathy, diabetic macular edema), non-endocrine tumors (breast, colon, prostate, lung, and hepatocellular), and digestive diseases (chronic refractory diarrhea, hepatorenal polycystosis, gastrointestinal hemorrhage, dumping syndrome, and intestinal fistula).

Long-acting somatostatin analogue treatments in autosomal dominant polycystic kidney disease and polycystic liver disease: a systematic review and meta-analysis

OBJECTIVES

A number of randomised control trials (RCTs) investigating the effects of long-acting somatostatin analogues in autosomal dominant polycystic kidney disease (ADPKD) and polycystic liver disease (PLD) have been recently reported. We sought to evaluate all available RCTs investigating the efficacy of somatostatin analogues treatment in ADPKD and PLD.

DATA SOURCES

Electronic databases; Pubmed, Clincaltrials.gov and Cochrane Central Register of Controlled Trials ELIGIBILITY CRITERIA FOR SELECTING STUDIES: RCTs and randomised cross-over trials comparing the effects of somatostatin analogue treatment with controls in patients with ADPKD or PLD.

DATA EXTRACTION AND SYNTHESIS

Data extraction and bias assessments were performed by two independent reviewers between January and May 2019. Outcomes assessed included estimated glomerular filtration rate (eGFR), total kidney volume (TKV), total liver volume (TLV), progression to end stage renal failure (ESRF) and adverse effects. Data were pooled using a random-effects model and reported as relative risk or mean difference with 95% CIs.

RESULTS

Meta-analysis was performed of six RCTs or randomised cross-over trials and three secondary analyses. A total of 592 patients were included. Compared with controls, somatostatin analogue treatment significantly reduced TLV (mean difference -0.15 L, 95% CI -0.26 to -0.03, p=0.01). There was no significant effect on TKV (mean difference -0.19 L, 95% CI -0.50 to 0.12, p=0.23) or eGFR (mean difference 0.27 mL/min/1.73 m², 95% CI -2.03 to 2.57, p=0.82). There was no effect on progression to ESRF. Somatostatin analogues were associated with known adverse effects such as gastrointestinal symptoms.

CONCLUSIONS

The available RCT data show improvement in TLV with somatostatin analogue treatment. There was no benefit to TKV or eGFR in patients with ADPKD, while being associated with various side effects. Further studies are needed to assess potential benefit in reducing cyst burden in patients with PLD.

ADPKD current management and ongoing trials

Among the diseases that require renal replacement therapy (RRT), ADPKD is the fourth for incidence and prevalence. In Italy, there are at least 32,000 patients affected by ADPKD, of which about 2900 in dialysis. The pure costs of dialysis treatment for the Italian National Health Service can be conservatively estimated at 87 million euros per year. Even a modest slowdown in the evolution of the disease would obtain an important result in terms of reduction of health expenditure. In recent years, many new or repurposed drugs have been evaluated in clinical trials for ADPKD. In this review we will mainly focus on advanced stage clinical trials (phase 2 and 3). We have grouped these studies according to the molecular pathway addressed by the experimental drug or the therapeutic strategy. More than 10 years after the start of the first Phase III clinical trials in ADPKD, the first drug active in slowing disease progression is finally available. It cannot be considered a goal but only the beginning of a journey because of the significant side effects and the high cost of Tolvaptan. An exuberant basic research activity in the field, together with the large number of ongoing protocols, keep the nephrologists and their patients positive with regard to the discovery of new and better therapies in a not-too-distant future.

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.

Targeted Therapies for Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common life-threatening genetic disease in humans, affecting approximately 1 in 500 people. ADPKD is characterized by cyst growth in the kidney leading to progressive parenchymal damage and is the underlying pathology in approximately 10% of patients requiring hemodialysis or transplantation for end-stage kidney disease. The two proteins that are mutated in ADPKD, polycystin-1 and polycystin-2, form a complex located on the primary cilium and the plasma membrane to facilitate calcium ion release in the cell. There is currently no Food and Drug Administration (FDA)-approved therapy to cure or slow the progression of the disease. Rodent ADPKD models do not completely mimic the human disease, and therefore preclinical results have not always successfully translated to the clinic. Moreover, the toxicity of many of these potential therapies has led to patient withdrawals from clinical trials.

RESULTS

Here, we review compounds in clinical trial for treating ADPKD, and we examine the feasibility of using a kidney-targeted approach, with potential for broadening the therapeutic window, decreasing treatment-associated toxicity and increasing the efficacy of agents that have demonstrated activity in animal models. We make recommendations for integrating kidney- targeted therapies with current treatment regimes, to achieve a combined approach to treating ADPKD.

CONCLUSION

Many compounds are currently in clinical trial for ADPKD yet, to date, none are FDA-approved for treating this disease. Patients could benefit from efficacious pharmacotherapy, especially if it can be kidney-targeted, and intensive efforts continue to be focused on this goal.

The pathobiology of polycystic kidney disease from a metabolic viewpoint

Autosomal dominant polycystic kidney disease (ADPKD) affects an estimated 1 in 1,000 people and slowly progresses to end-stage renal disease (ESRD) in about half of these individuals. Tolvaptan, a vasopressin 2 receptor blocker, has been approved by regulatory authorities in many countries as a therapy to slow cyst growth, but additional treatments that target dysregulated signalling pathways in cystic kidney and liver are needed. Metabolic reprogramming is a prominent feature of cystic cells and a potentially important contributor to the pathophysiology of ADPKD. A number of pathways previously implicated in the pathogenesis of the disease, such as dysregulated mTOR and primary ciliary signalling, have roles in metabolic regulation and may exert their effects through this mechanism. Some of these pathways are amenable to manipulation through dietary modifications or drug therapies. Studies suggest that polycystin-1 and polycystin-2, which are encoded by PKD1 and PKD2, respectively (the genes that are mutated in >99% of patients with ADPKD), may in part affect cellular metabolism through direct effects on mitochondrial function. Mitochondrial dysfunction could alter the redox state and cellular levels of acetyl-CoA, resulting in altered histone acetylation, gene expression, cytoskeletal architecture and response to cellular stress, and in an immunological response that further promotes cyst growth and fibrosis.

Octreotide-LAR in later-stage autosomal dominant polycystic kidney disease (ALADIN 2): A randomized, double-blind, placebo-controlled, multicenter trial

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent genetically determined renal disease. In affected patients, renal function may progressively decline up to end-stage renal disease (ESRD), and approximately 10% of those with ESRD are affected by ADPKD. The somatostatin analog octreotide long-acting release (octreotide-LAR) slows renal function deterioration in patients in early stages of the disease. We evaluated the renoprotective effect of octreotide-LAR in ADPKD patients at high risk of ESRD because of later-stage ADPKD.

METHODS AND FINDINGS

We did an internally funded, parallel-group, double-blind, placebo-controlled phase III trial to assess octreotide-LAR in adults with ADPKD with glomerular filtration rate (GFR) 15-40 ml/min/1.73 m2. Participants were randomized to receive 2 intramuscular injections of 20 mg octreotide-LAR (n = 51) or 0.9% sodium chloride solution (placebo; n = 49) every 28 days for 3 years. Central randomization was 1:1 using a computerized list stratified by center and presence or absence of diabetes or proteinuria. Co-primary short- and long-term outcomes were 1-year total kidney volume (TKV) (computed tomography scan) growth and 3-year GFR (iohexol plasma clearance) decline. Analyses were by modified intention-to-treat. Patients were recruited from 4 Italian nephrology units between October 11, 2011, and March 20, 2014, and followed up to April 14, 2017. Baseline characteristics were similar between groups. Compared to placebo, octreotide-LAR reduced median (95% CI) TKV growth from baseline by 96.8 (10.8 to 182.7) ml at 1 year (p = 0.027) and 422.6 (150.3 to 695.0) ml at 3 years (p = 0.002). Reduction in the median (95% CI) rate of GFR decline (0.56 [-0.63 to 1.75] ml/min/1.73 m2 per year) was not significant (p = 0.295). TKV analyses were adjusted for age, sex, and baseline TKV. Over a median (IQR) 36 (24 to 37) months of follow-up, 9 patients on octreotide-LAR and 21 patients on placebo progressed to a doubling of serum creatinine or ESRD (composite endpoint) (hazard ratio [HR] [95% CI] adjusted for age, sex, baseline serum creatinine, and baseline TKV: 0.307 [0.127 to 0.742], p = 0.009). One composite endpoint was prevented for every 4 treated patients. Among 63 patients with chronic kidney disease (CKD) stage 4, 3 on octreotide-LAR and 8 on placebo progressed to ESRD (adjusted HR [95% CI]: 0.121 [0.017 to 0.866], p = 0.036). Three patients on placebo had a serious renal cyst rupture/infection and 1 patient had a serious urinary tract infection/obstruction, versus 1 patient on octreotide-LAR with a serious renal cyst infection. The main study limitation was the small sample size.

CONCLUSIONS

In this study we observed that in later-stage ADPKD, octreotide-LAR slowed kidney growth and delayed progression to ESRD, in particular in CKD stage 4.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01377246; EudraCT: 2011-000138-12.

Autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and one of the most common causes of end-stage kidney disease. Multiple clinical manifestations, such as enlarged kidneys filled with growing cysts, hypertension, and multiple extrarenal complications, including liver cysts, intracranial aneurysms, and cardiac valvular disease, show that ADPKD is a systemic disorder. New information derived from clinical research using molecular genetics and advanced imaging techniques has provided enhanced tools for assessing the diagnosis and prognosis for individual patients and their families. Phase 3 randomised, placebo-controlled clinical trials have clarified aspects of disease management and a disease-modifying therapeutic drug is now available for patients with high risk of rapid disease progression. These developments provide a strong basis on which to make clear recommendations about the management of affected patients and families. Implementation of these advances has the potential to delay kidney failure, reduce the symptom burden, lessen the risk of cardiovascular complications, and prolong life.

Autosomal dominant polycystic kidney disease: Disrupted pathways and potential therapeutic interventions

Autosomal dominant polycystic kidney disease (ADPKD) is a monogenic inherited renal cystic disease that occurs in different races worldwide. It is characterized by the development of a multitude of renal cysts, which leads to massive enlargement of the kidney and often to renal failure in adulthood. ADPKD is caused by a mutation in PKD1 or PKD2 genes encoding the proteins polycystin-1 and polycystin-2, respectively. Recent studies showed that cyst formation and growth result from deregulation of multiple cellular pathways like proliferation, apoptosis, metabolic processes, cell polarity, and immune defense. In ADPKD, intracellular cyclic adenosine monophosphate (cAMP) promotes cyst enlargement by stimulating cell proliferation and transepithelial fluid secretion. Several interventions affecting many of these defective signaling pathways have been effective in animal models and some are currently being tested in clinical trials. Moreover, the stem cell therapy can improve nephropathies and according to studies were done in this field, can be considered as a hopeful therapeutic approach in future for PKD. This study provides an in-depth review of the relevant molecular pathways associated with the pathogenesis of ADPKD and their implications in development of potential therapeutic strategies.

Association of plasma somatostatin with disease severity and progression in patients with autosomal dominant polycystic kidney disease

Background

Somatostatin (SST) inhibits intracellular cyclic adenosine monophosphate (cAMP) production and thus may modify cyst formation in autosomal dominant polycystic kidney disease (ADPKD). We investigated whether endogenous plasma SST concentration is associated with disease severity and progression in patients with ADPKD, and whether plasma SST concentrations change during treatment with a vasopressin V2 receptor antagonist or SST analogue.

Methods

In this observational study, fasting concentrations of SST were measured in 127 ADPKD patients (diagnosed upon the revised Ravine criteria) by ELISA. cAMP was measured in 24 h urine by Radio Immuno Assay. Kidney function was measured (mGFR) as ¹²⁵I-iothalamate clearance, and total kidney volume was measured by MRI volumetry and adjusted for height (htTKV). Disease progression was expressed as annual change in mGFR and htTKV. Additionally, baseline versus follow-up SST concentrations were compared in ADPKD patients during vasopressin V2 receptor antagonist (tolvaptan) (n = 27) or SST analogue (lanreotide) treatment (n = 25).

Results

In 127 ADPKD patients, 41 ± 11 years, 44% female, eGFR 73 ± 32 ml/min/1.73m², mGFR 75 ± 32 ml/min/1.73m² and htTKV 826 (521–1297) ml/m, SST concentration was 48.5 (34.3–77.8) pg/ml. At baseline, SST was associated with urinary cAMP, mGFR and htTKV (p = 0.02, p = 0.004 and p = 0.02, respectively), but these associations lost significance after adjustment for age and sex or protein intake (p = 0.09, p = 0.06 and p = 0.15 respectively). Baseline SST was not associated with annual change in mGFR, or htTKV during follow-up (st. β = − 0.02, p = 0.87 and st. β = − 0.07, p = 0.54 respectively). During treatment with tolvaptan SST levels remained stable 38.2 (23.8–70.7) pg/mL vs. 39.8 (31.2–58.5) pg/mL, p = 0.85), whereas SST levels decreased significantly during treatment with lanreotide (42.5 (33.2–55.0) pg/ml vs. 29.3 (24.8–37.6), p = 0.008).

Conclusions

Fasting plasma SST concentration is not associated with disease severity or progression in patients with ADPKD. Treatment with lanreotide caused a decrease in SST concentration. These data suggest that plasma SST cannot be used as a biomarker to assess prognosis in ADPKD, but leave the possibility open that change in SST concentration during lanreotide treatment may reflect therapy efficacy.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1176-y) contains supplementary material, which is available to authorized users.

Effect of Lanreotide on Kidney Function in Patients With Autosomal Dominant Polycystic Kidney Disease: The DIPAK 1 Randomized Clinical Trial

IMPORTANCE

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst formation in both kidneys and loss of renal function, eventually leading to a need for kidney replacement therapy. There are limited therapeutic management options.

OBJECTIVE

To examine the effect of the somatostatin analogue lanreotide on the rate of kidney function loss in patients with later-stage ADPKD.

DESIGN, SETTING, AND PARTICIPANTS

An open-label randomized clinical trial with blinded end point assessment that included 309 patients with ADPKD from July 2012 to March 2015 at 4 nephrology outpatient clinics in the Netherlands. Eligible patients were 18 to 60 years of age and had an estimated glomerular filtration rate (eGFR) of 30 to 60 mL/min/1.73 m2. Follow-up of the 2.5-year trial ended in August 2017.

INTERVENTIONS

Patients were randomized to receive either lanreotide (120 mg subcutaneously once every 4 weeks) in addition to standard care (n = 153) or standard care only (target blood pressure <140/90 mm Hg; n = 152).

MAIN OUTCOMES AND MEASURES

Primary outcome was annual change in eGFR assessed as slope through eGFR values during the 2.5-year treatment phase. Secondary outcomes included change in eGFR before vs after treatment, incidence of worsening kidney function (start of dialysis or 30% decrease in eGFR), change in total kidney volume and change in quality of life (range: 1 [not bothered] to 5 [extremely bothered]).

RESULTS

Among the 309 patients who were randomized (mean [SD] age, 48.4 [7.3] years; 53.4% women), 261 (85.6%) completed the trial. Annual rate of eGFR decline for the lanreotide vs the control group was -3.53 vs -3.46 mL/min/1.73 m2 per year (difference, -0.08 [95% CI, -0.71 to 0.56]; P = .81). There were no significant differences for incidence of worsening kidney function (hazard ratio, 0.87 [95% CI, 0.49 to 1.52]; P = .87), change in eGFR (-3.58 vs -3.45; difference, -0.13 mL/min/1.73 m2 per year [95% CI, -1.76 to 1.50]; P = .88), and change in quality of life (0.05 vs 0.07; difference, -0.03 units per year [95% CI, -0.13 to 0.08]; P = .67). The rate of growth in total kidney volume was lower in the lanreotide group than the control group (4.15% vs 5.56%; difference, -1.33% per year [95% CI, -2.41% to -0.24%]; P = .02). Adverse events in the lanreotide vs control group included injection site discomfort (32% vs 0.7%), injection site papule (5.9% vs 0%), loose stools (91% vs 6.6%), abdominal discomfort (79% vs 20%), and hepatic cyst infections (5.2% vs 0%).

CONCLUSIONS AND RELEVANCE

Among patients with later-stage autosomal dominant polycystic kidney disease, treatment with lanreotide compared with standard care did not slow the decline in kidney function over 2.5 years of follow-up. These findings do not support the use of lanreotide for treatment of later-stage autosomal dominant polycystic kidney disease.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01616927.

The expression of somatostatin receptor 2 decreases during cyst growth in mice with polycystic kidney disease

IMPACT STATEMENT

Somatostatin (SST) analogs have been shown to halt cyst growth and progression of autosomal dominant polycystic kidney disease by several clinical trials. However, two studies suggest that the effect of the SST analog octreotide on kidney growth during the first year of treatment is reduced in the subsequent follow-ups and the kidney enlargement resumes. This biphasic change in kidney growth during octreotide treatment may be partially explained by alterations in SSTR2 expression. Here, we found that SSTR2 is mainly expressed in distal tubules and collecting ducts in murine kidneys, and the expression of SSTR2 decreases during cyst growth in two PKD mouse models. Our data may thus provide possible explanations for the lack of efficacy in long-term treatment with SST analogs.

Clinical Features of 167 Inpatients with Autosomal Dominant Polycystic Kidney Disease at a Single Center in China

BACKGROUND The aim of this study was to describe the clinical characteristics of Chinese ADPKD inpatients and to identify the factors associated with disease severity. MATERIAL AND METHODS We included 167 hospitalized patients (inpatients) with ADPKD in this study. Multiple regression analyses were conducted to determine factors correlated with estimated glomerular filtration rate (eGFR). Patients were stratified into subgroups according to the presence of symptoms, in which clinical parameters were analyzed and compared. RESULTS The mean age of hospitalized ADPKD patients was 48.7 years old, lumbar and/or abdominal pain was seen in 40.12% of patients, following by nephrolithiasis (38.92%), hematuria (30.54%), and urinary tract infection (24.55%). Serum thrombocyte level and hemoglobin exhibited significant positive correlations with eGFR. Symptomatic patients accounted for 71.26% of the studied population. Patients with hypertension had increased risk of presence of symptoms (OR=2.794, 95%CI=1.341-5.822). Low thrombocyte and hemoglobin levels were observed in patients with hematuria. CONCLUSIONS Thrombocyte level was positively correlated with eGFR but was not associated with presence of PKD-related symptoms, suggesting thrombocyte level might be an independent serum biomarker for disease progression. Hypertension was associated with increased risk of symptom occurrence, indicating the relationship between hypertension and disease progression. This study reveals the clinical characteristics of inpatients with ADPKD in China and provides clinicians with useful insights into this intractable disease.

Fully Automated Segmentation of Polycystic Kidneys From Noncontrast Computed Tomography: A Feasibility Study and Preliminary Results

RATIONALE AND OBJECTIVES

Total kidney volume is an important biomarker for the evaluation of autosomal dominant polycystic kidney disease progression. In this study, we present a novel approach for automated segmentation of polycystic kidneys from non-contrast-enhanced computed tomography (CT) images.

MATERIALS AND METHODS

Non-contrast-enhanced CT images were acquired from 21 patients with a diagnosis of autosomal dominant polycystic kidney disease. Kidney volumes obtained from the fully automated method were compared to volumes obtained by manual segmentation and evaluated using linear regression and Bland-Altman analyses. Dice coefficient was used for performance evaluation.

RESULTS

Kidney volumes from the automated method well correlated with the ones obtained by manual segmentation. Bland-Altman analysis showed a low percentage bias (-0.3%) and narrow limits of agreements (11.0%). The overlap between the three-dimensional kidney surfaces obtained with our approach and by manual tracing, expressed in terms of Dice coefficient, showed good agreement (0.91 ± 0.02).

CONCLUSIONS

This preliminary study showed the proposed fully automated method for renal volume assessment is feasible, exhibiting how a correct use of biomedical image processing may allow polycystic kidney segmentation also in non-contrast-enhanced CT. Further investigation on a larger dataset is needed to confirm the robustness of the presented approach.

Prognostic enrichment design in clinical trials for autosomal dominant polycystic kidney disease: the HALT-PKD clinical trial

Background

Patients with mild autosomal dominant polycystic kidney disease (ADPKD) are less likely to be informative in randomized clinical trials (RCTs). We previously developed an imaging classification of ADPKD (typical diffuse cyst distribution Class 1A-E and atypical cyst distribution Class 2) for prognostic enrichment design in RCTs. We investigated whether using this classification would have increased the power to detect a beneficial treatment effect of rigorous blood pressure (BP) control on HALT-PKD participants with early disease (Study A).

Methods

Post hoc analysis of the early disease HALT-PKD study, an RCT that studied the effect of rigorous versus standard BP control on rates of total kidney volume (TKV) increase and estimated glomerular filtration rate (eGFR) decline in ADPKD patients with eGFR >60 mL/min/1.73 m2.

Results

Five hundred and fifty-one patients were classified by two observers (98.2% agreement) into Class 1A (6.2%), 1B (20.3%), 1C (34.1%), 1D (22.1%), 1E (11.8%) and 2 (5.4%). The TKV increase and eGFR decline became steeper from Class 1A through 1E. Rigorous BP control had been shown to be associated with slower TKV increase, without a significant overall effect on the rate of eGFR decline (faster in the first 4 months and marginally slower thereafter). Merging Classes 1A and 2 (lowest severity), 1B and 1C (intermediate severity) and 1D and 1E (highest severity) detected stronger beneficial effects on TKV increase and eGFR decline in Class 1D and E with a smaller number of patients.

Conclusions

Strategies for prognostic enrichment, such as image classification, should be used in the design of RCTs for ADPKD to increase their power and reduce their cost.

Quantitative magnetic resonance imaging assessments of autosomal recessive polycystic kidney disease progression and response to therapy in an animal model

BackgroundAutosomal recessive polycystic kidney disease (ARPKD) is associated with significant mortality and morbidity, and currently, there are no disease-specific treatments available for ARPKD patients. One major limitation in establishing new therapies for ARPKD is a lack of sensitive measures of kidney disease progression. Magnetic resonance imaging (MRI) can provide multiple quantitative assessments of the disease.MethodsWe applied quantitative image analysis of high-resolution (noncontrast) T2-weighted MRI techniques to study cystic kidney disease progression and response to therapy in the PCK rat model of ARPKD.ResultsSerial imaging over a 2-month period demonstrated that renal cystic burden (RCB, %)=[total cyst volume (TCV)/total kidney volume (TKV) × 100], TCV, and, to a lesser extent, TKV detected cystic kidney disease progression, as well as the therapeutic effect of octreotide, a clinically available medication shown previously to slow both kidney and liver disease progression in this model. All three MRI measures correlated significantly with histologic measures of renal cystic area, although the correlation of RCB and TCV was stronger than that of TKV.ConclusionThese preclinical MRI results provide a basis for applying these quantitative MRI techniques in clinical studies, to stage and measure progression in human ARPKD kidney disease.

Canonical Wnt inhibitors ameliorate cystogenesis in a mouse ortholog of human ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) can be caused by mutations in the PKD1 or PKD2 genes. The PKD1 gene product is a Wnt cell-surface receptor. We previously showed that a lack of the PKD2 gene product, PC2, increases β-catenin signaling in mouse embryonic fibroblasts, kidney renal epithelia, and isolated renal collecting duct cells. However, it remains unclear whether β-catenin signaling plays a role in polycystic kidney disease phenotypes or if a Wnt inhibitor can halt cyst formation in ADPKD disease models. Here, using genetic and pharmacologic approaches, we demonstrated that the elevated β-catenin signaling caused by PC2 deficiency contributes significantly to disease phenotypes in a mouse ortholog of human ADPKD. Pharmacologically inhibiting β-catenin stability or the production of mature Wnt protein, or genetically reducing the expression of Ctnnb1 (which encodes β-catenin), suppressed the formation of renal cysts, improved renal function, and extended survival in ADPKD mice. Our study clearly demonstrates the importance of β-catenin signaling in disease phenotypes associated with Pkd2 mutation. It also describes the effects of two Wnt inhibitors, XAV939 and LGK974, on various Wnt signaling targets as a potential therapeutic modality for ADPKD, for which there is currently no effective therapy.

Hepatic Cyst Infection During Use of the Somatostatin Analog Lanreotide in Autosomal Dominant Polycystic Kidney Disease: An Interim Analysis of the Randomized Open-Label Multicenter DIPAK-1 Study

Introduction and Aims

The DIPAK-1 Study investigates the reno- and hepatoprotective efficacy of the somatostatin analog lanreotide compared with standard care in patients with later stage autosomal dominant polycystic kidney disease (ADPKD). During this trial, we witnessed several episodes of hepatic cyst infection, all during lanreotide treatment. We describe these events and provide a review of the literature.

Methods

The DIPAK-1 Study is an ongoing investigator-driven, randomized, controlled, open-label multicenter trial. Patients (ADPKD, ages 18–60 years, estimated glomerular filtration rate 30–60 mL/min/1.73 m²) were randomized 1:1 to receive lanreotide 120 mg subcutaneously every 28 days or standard care during 120 weeks. Hepatic cyst infection was diagnosed by local physicians.

Results

We included 309 ADPKD patients of which seven (median age 53 years [interquartile range: 48–55], 71% female, median estimated glomerular filtration rate 42 mL/min/1.73 m² [interquartile range: 41–58]) developed eight episodes of hepatic cyst infection during 342 patient-years of lanreotide use (0.23 cases per 10 patient-years). These events were limited to patients receiving lanreotide (p < 0.001 vs. standard care). Baseline characteristics were similar between subjects who did or did not develop a hepatic cyst infection during lanreotide use, except for a history of hepatic cyst infection (29 vs. 0.7%, p < 0.001). Previous studies with somatostatin analogs reported cyst infections, but did not identify a causal relationship.

Conclusions

These data suggest an increased risk for hepatic cyst infection during use of somatostatin analogs, especially in ADPKD patients with a history of hepatic cyst infection. The main results are still awaited to fully appreciate the risk–benefit ratio.

ClinicalTrials.gov identifier

NCT 01616927.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-016-0486-x) contains supplementary material, which is available to authorized users.

Standardised Outcomes in Nephrology-Polycystic Kidney Disease (SONG-PKD): study protocol for establishing a core outcome set in polycystic kidney disease

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common potentially life threatening inherited kidney disease and is responsible for 5–10% of cases of end-stage kidney disease (ESKD). Cystic kidneys may enlarge up to 20 times the weight of a normal kidney due to the growth of renal cysts, and patients with ADPKD have an increased risk of morbidity, premature mortality, and other life-time complications including renal and hepatic cyst and urinary tract infection, intracranial aneurysm, diverticulosis, and kidney pain which impair quality of life. Despite some therapeutic advances and the growing number of clinical trials in ADPKD, the outcomes that are relevant to patients and clinicians, such as symptoms and quality of life, are infrequently and inconsistently reported. This potentially limits the contribution of trials to inform evidence-based decision-making. The Standardised Outcomes in Nephrology—Polycystic Kidney Disease (SONG-PKD) project aims to establish a consensus-based set of core outcomes for trials in PKD (with an initial focus on ADPKD but inclusive of all stages) that patients and health professionals identify as critically important.

Methods

The five phases of SONG-PKD are: a systematic review to identify outcomes that have been reported in existing PKD trials; focus groups with nominal group technique with patients and caregivers to identify, rank, and describe reasons for their choices; qualitative stakeholder interviews with health professionals to elicit individual values and perspectives on outcomes for trials involving patients with PKD; an international three-round Delphi survey with all stakeholder groups (including patients, caregivers, healthcare providers, policy makers, researchers, and industry) to gain consensus on critically important core outcome domains; and a consensus workshop to review and establish a set of core outcome domains and measures for trials in PKD.

Discussion

The SONG-PKD core outcome set is aimed at improving the consistency and completeness of outcome reporting across ADPKD trials, leading to improvements in the reliability and relevance of trial-based evidence to inform decisions about treatment and ultimately improve the care and outcomes for people with ADPKD.