Safety Profile of Tolvaptan in the Treatment of Autosomal Dominant Polycystic Kidney Disease

Novel Potential Therapeutic Targets in Autosomal Dominant Polycystic Kidney Disease from the Perspective of Cell Polarity and Fibrosis

Autosomal dominant polycystic kidney disease (ADPKD), a congenital genetic disorder, is a notable contributor to the prevalence of chronic kidney disease worldwide. Despite the absence of a complete cure, ongoing research aims for early diagnosis and treatment. Although agents such as tolvaptan and mTOR inhibitors have been utilized, their effectiveness in managing the disease during its initial phase has certain limitations. This review aimed to explore new targets for the early diagnosis and treatment of ADPKD, considering ongoing developments. We particularly focus on cell polarity, which is a key factor that influences the process and pace of cyst formation. In addition, we aimed to identify agents or treatments that can prevent or impede the progression of renal fibrosis, ultimately slowing its trajectory toward end-stage renal disease. Recent advances in slowing ADPKD progression have been examined, and potential therapeutic approaches targeting multiple pathways have been introduced. This comprehensive review discusses innovative strategies to address the challenges of ADPKD and provides valuable insights into potential avenues for its prevention and treatment.

Repurposing calcium-sensing receptor activator drug cinacalcet for ADPKD treatment

ADPKD is characterized by progressive cyst formation and enlargement leading to kidney failure. Tolvaptan is currently the only FDA-approved treatment for ADPKD; however, it can cause serious adverse effects including hepatotoxicity. There remains an unmet clinical need for effective and safe treatments for ADPKD. The extracellular Ca2+-sensing receptor (CaSR) is a regulator of epithelial ion transport. FDA-approved CaSR activator cinacalcet can reduce cAMP-induced Cl- and fluid secretion in various epithelial cells by activating phosphodiesterases (PDE) that hydrolyze cAMP. Since elevated cAMP is a key mechanism of ADPKD progression by promoting cell proliferation, cyst formation and enlargement (via Cl- and fluid secretion), here we tested efficacy of cinacalcet in cell and animal models of ADPKD. Cinacalcet treatment reduced cAMP-induced Cl- secretion and CFTR activity in MDCK cells as suggested by ∼70 % lower short-circuit current (Isc) changes in response to forskolin and CFTRinh-172, respectively. Cinacalcet treatment inhibited forskolin-induced cAMP elevation by 60 % in MDCK cells, and its effect was completely reversed by IBMX (PDE inhibitor). In MDCK cells treated with forskolin, cinacalcet treatment concentration-dependently reduced cell proliferation, cyst formation and cyst enlargement by up to 50 % without affecting cell viability. Cinacalcet treatment (20 mg/kg/day for 7 days, subcutaneous) reduced renal cyst index in a mouse model of ADPKD (Pkd1flox/flox;Ksp-Cre) by 20 %. Lastly, cinacalcet treatment reduced cyst enlargement and cell proliferation in human ADPKD cells by 60 %. Considering its efficacy as shown here, and favorable safety profile including extensive post-approval data, cinacalcet can be repurposed as a novel ADPKD treatment.

Inhibiting centrosome clustering reduces cystogenesis and improves kidney function in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a monogenic disorder accounting for approximately 5% of patients with renal failure, yet therapeutics for the treatment of ADPKD remain limited. ADPKD tissues display abnormalities in the biogenesis of the centrosome, a defect that can cause genome instability, aberrant ciliary signaling, and secretion of pro-inflammatory factors. Cystic cells form excess centrosomes via a process termed centrosome amplification (CA), which causes abnormal multipolar spindle configurations, mitotic catastrophe, and reduced cell viability. However, cells with CA can suppress multipolarity via "centrosome clustering," a key mechanism by which cells circumvent apoptosis. Here, we demonstrate that inhibiting centrosome clustering can counteract the proliferation of renal cystic cells with high incidences of CA. Using ADPKD human cells and mouse models, we show that preventing centrosome clustering with 2 inhibitors, CCB02 and PJ34, blocks cyst initiation and growth in vitro and in vivo. Inhibiting centrosome clustering activates a p53-mediated surveillance mechanism leading to apoptosis, reduced cyst expansion, decreased interstitial fibrosis, and improved kidney function. Transcriptional analysis of kidneys from treated mice identified pro-inflammatory signaling pathways implicated in CA-mediated cystogenesis and fibrosis. Our results demonstrate that centrosome clustering is a cyst-selective target for the improvement of renal morphology and function in ADPKD.

Prioritized polycystic kidney disease drug targets and repurposing candidates from pre-cystic and cystic mouse Pkd2 model gene expression reversion

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most prevalent monogenic human diseases. It is mostly caused by pathogenic variants in PKD1 or PKD2 genes that encode interacting transmembrane proteins polycystin-1 (PC1) and polycystin-2 (PC2). Among many pathogenic processes described in ADPKD, those associated with cAMP signaling, inflammation, and metabolic reprogramming appear to regulate the disease manifestations. Tolvaptan, a vasopressin receptor-2 antagonist that regulates cAMP pathway, is the only FDA-approved ADPKD therapeutic. Tolvaptan reduces renal cyst growth and kidney function loss, but it is not tolerated by many patients and is associated with idiosyncratic liver toxicity. Therefore, additional therapeutic options for ADPKD treatment are needed.

METHODS

As drug repurposing of FDA-approved drug candidates can significantly decrease the time and cost associated with traditional drug discovery, we used the computational approach signature reversion to detect inversely related drug response gene expression signatures from the Library of Integrated Network-Based Cellular Signatures (LINCS) database and identified compounds predicted to reverse disease-associated transcriptomic signatures in three publicly available Pkd2 kidney transcriptomic data sets of mouse ADPKD models. We focused on a pre-cystic model for signature reversion, as it was less impacted by confounding secondary disease mechanisms in ADPKD, and then compared the resulting candidates' target differential expression in the two cystic mouse models. We further prioritized these drug candidates based on their known mechanism of action, FDA status, targets, and by functional enrichment analysis.

RESULTS

With this in-silico approach, we prioritized 29 unique drug targets differentially expressed in Pkd2 ADPKD cystic models and 16 prioritized drug repurposing candidates that target them, including bromocriptine and mirtazapine, which can be further tested in-vitro and in-vivo.

CONCLUSION

Collectively, these results indicate drug targets and repurposing candidates that may effectively treat pre-cystic as well as cystic ADPKD.

Diet and Polycystic Kidney Disease: Nutrients, Foods, Dietary Patterns, and Implications for Practice

Polycystic kidney disease (PKD) is a chronic, progressive hereditary condition characterized by abnormal development and growth of cysts in the kidneys and other organs. There is increasing interest in exploring whether dietary modifications may prevent or slow the disease course in people with PKD. Although vasopressin-receptor agonists have emerged as a novel drug treatment in advancing care for people with PKD, several recent landmark trials and clinical discoveries also have provided new insights into potential dietary-related therapeutic strategies. In this review, we summarize the current evidence pertaining to nutrients, foods, dietary patterns, cyst growth, and progression of PKD. We also describe existing evidence-based dietary care for people with PKD and outline the potential implications for advancing evidence-based dietary interventions. Semin Nephrol 43:x-xx © 2023 Elsevier Inc. All rights reserved.

Clinical Pattern of Tolvaptan-Associated Liver Injury in Trial Participants With Autosomal Dominant Polycystic Kidney Disease (ADPKD): An Analysis of Pivotal Clinical Trials

RATIONALE & OBJECTIVE

Tolvaptan is associated with risk of drug-induced liver injury when used to treat autosomal dominant polycystic kidney disease (ADPKD). After this risk was described based on the clinical trials TEMPO 3:4 and TEMPO 4:4, additional data from the REPRISE trial and a long-term extension of TEMPO 4:4, REPRISE, and other tolvaptan trials in ADPKD have become available. To further characterize the hepatic safety profile of tolvaptan, an analysis of the expanded dataset was conducted.

STUDY DESIGN

Analysis of safety data from prospective clinical trials of tolvaptan.

SETTING & PARTICIPANTS

Multicenter clinical trials including more than 2,900 tolvaptan-treated participants, more than 2,300 with at least 18 months of drug exposure.

INTERVENTION

Tolvaptan administered twice daily in split-dose regimens.

OUTCOMES

Frequency of liver enzyme level increases detected by regular laboratory monitoring.

RESULTS

In the placebo-controlled REPRISE trial, more tolvaptan- than placebo-treated participants (38 of 681 [5.6%] vs 8 of 685 [1.2%]) experienced alanine aminotransferase level increases to >3× the upper limit of normal (ULN), similar to TEMPO 3:4 (40 of 957 [4.4%] vs 5 of 484 [1.0%]). No participant in REPRISE or the long-term extension experienced concurrent alanine aminotransferase level increases to >3× ULN and total bilirubin increases to >2× ULN ("Hy's Law" laboratory criteria). Based on the expanded dataset, liver enzyme increases most often occurred within 18 months after tolvaptan initiation and were less frequent thereafter. Increased levels returned to normal or near normal after treatment interruption or discontinuation. Thirty-eight patients were rechallenged with tolvaptan after the initial drug-induced liver injury episode, with return of liver enzyme level increases in 30; 1 additional participant showed a clinical "adaptation" after the initial episode, with resolution of the enzyme level increases despite continuation of tolvaptan.

LIMITATIONS

Retrospective analysis.

CONCLUSIONS

The absence of Hy's Law cases in REPRISE and the long-term extension trial support monthly liver enzyme monitoring during the first 18 months of tolvaptan exposure and every 3 months thereafter to detect and manage enzyme level increases, as is recommended on the drug label.

FUNDING

Otsuka Pharmaceutical Development & Commercialization, Inc.

TRIAL REGISTRATION

Trials included in the dataset were registered at ClinicalTrials.gov with study numbers NCT00428948 (TEMPO 3:4), NCT01214421 (TEMPO 4:4), NCT02160145 (REPRISE), and NCT02251275 (long-term extension).

Efficacy of tolvaptan on the short and mid-term prognosis in elderly patients with acute heart failure coexisting with oliguria: A retrospective cohort study

Background

In patients with acute heart failure (AHF) coexisting with oliguria, high doses of loop diuretics are often ineffective in increasing urine output and may adversely affect the patient's prognosis, especially in elderly patients. We investigated the efficacy of adding tolvaptan (TLV) on improving the prognosis in elderly patients with AHF coexisting with oliguria.

Methods

All data for this retrospective cohort study were extracted from the electronic medical record system of the Second Medical Center of Chinese PLA General Hospital from January 2018 to December 2020. Patients diagnosed with AHF coexisting with oliguria were enrolled in this study and were divided into TLV and non-TLV groups based on the use of TLV. The primary outcome was all-cause mortality at 7 and 90-day. The secondary outcomes were the remission of AHF within 7 and 30 days or continued progression of AHF, and new-onset chronic kidney disease (CKD) after 90 days. Cox proportional hazards regression was used to assess the relationships between all-cause mortality and diuretic regimens, demographics, laboratory parameters, comorbidities, and medications.

Results

A total of 308 patients met the study criteria for the final statistical analysis, and they had a median age of 91 years (88, 95). The results showed that the addition of TLV was associated with a decreased risk of the 7 and 90-day all-cause mortality in patients with AHF with oliguria [adjusted HR, 95% CI: 0.60 (0.37, 0.98), p = 0.042; 0.56 (0.41, 0.75), p < 0.001, respectively]. Adding TLV significantly increased urine output and decreased N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in 7 days, and alleviated the progression of AHF within 30 days. There were no statistically significant differences between the patients with or without TLV in terms of the occurrence of hypernatremia, the development of hepatic impairment within 30 days, and new-onset CKD after 90 days.

Conclusions

This study demonstrated that the addition of TLV was clinically effective in increasing urine output, and had favorable effects on alleviating AHF progression and may reduce the risk of all-cause mortality at 7 and 90-day in elderly patients with AHF with oliguria, and TLV had a good safety profile.

Trial registration

http://www.chictr.org.cn/showprojen.aspx?proj=148046, identifier: ChiCTR2200055518.

The role of tolvaptan in pulmonary hypertension: A retrospective study

Pulmonary hypertension (PH) is a severe form of pulmonary vascular disease that can lead to right heart failure (RHF). Nearly 2-thirds of patients with PH die within 5 years. Studies suggest that a new diuretic medication, called tolvaptan (TLV), can be used to treat PH. However, there is still insufficient evidence to confirm its effectiveness. Therefore, we investigated the role of TLV in patients with PH. This retrospective study included 73 patients with PH hospitalized in Shanghai Pulmonary Hospital between November 2019 and March 2022. All patients received 7.5 to 15.0 mg of TLV for 3 to 21 days starting at admission, in addition to targeted drugs and traditional diuretic therapy. The outcomes included the blood pressure, urine and water intake volumes, electrolyte concentrations, and renal, liver, and cardiac function indexes before and after TLV treatment. In addition, we assessed the clinical symptoms and adverse reactions during the treatment. After TLV treatment, the water intake and urine volumes significantly increased, and body weight, diastolic blood pressure (DBP) and mean arterial pressure significantly decreased. Total bilirubin, direct bilirubin, N-terminal pro-brain natriuretic peptide, and serum uric acid (UA) levels after TLV treatment were significantly lower than before treatment. After TLV treatment, dyspnea significantly improved in 71 of 73 patients, and lower limb edema disappeared in 42 of 53 patients. No obvious adverse reactions occurred during the TLV treatment period. These results suggest that adding TLV to targeted drug and traditional diuretic therapies is effective for patients with PH. However, more data are required to support these findings.

N-(4-acetamidophenyl)-5-acetylfuran-2-carboxamide as a novel orally available diuretic that targets urea transporters with improved PD and PK properties

Urea transporters (UTs) have been identified as new targets for diuretics. Functional deletion of UTs led to urea-selective urinary concentrating defects with relative salt sparing. In our previous study, a UT inhibitor with a diarylamide scaffold, which is denoted as 11a, was demonstrated as the first orally available UT inhibitor. However, the oral bioavailability of 11a was only 4.38%, which obstructed its clinical application. In this work, by replacing the nitro group of 11a with an acetyl group, 25a was obtained. Compared with 11a, 25a showed a 10 times stronger inhibitory effect on UT-B (0.14 μM vs. 1.41 μM in rats, and 0.48 μM vs. 5.82 μM in mice) and a much higher inhibition rate on UT-A1. Moreover, the metabolic stability both in vitro and in vivo and the drug-like properties (permeability and solubility) of 25a were obviously improved compared with those of 11a. Moreover, the bioavailability of 25a was 15.18%, which was 3 times higher than that of 11a, thereby resulting in significant enhancement of the diuretic activities in rats and mice. 25a showed excellent potential for development as a promising clinical diuretic candidate for targeting UTs to treat diseases that require long-term usage of diuretics, such as hyponatremia.