The Vasopressin Receptor Antagonist Tolvaptan Counteracts Tumor Growth in a Murine Xenograft Model of Small Cell Lung Cancer.

We have previously demonstrated that the vasopressin type 2 receptor (AVPR2) antagonist tolvaptan reduces cell proliferation and invasion and triggers apoptosis in different human cancer cell lines. To study this effect in vivo, a xenograft model of small cell lung cancer was developed in Fox1nu/nu nude mice through the subcutaneous inoculation of H69 cells, which express AVPR2. One group of mice (n = 5) was treated with tolvaptan for 60 days, whereas one group (n = 5) served as the control. A reduced growth was observed in the tolvaptan group in which the mean tumor volume was significantly smaller on day 60 compared to the control group. In the latter group, a significantly lower survival was observed. The analysis of excised tumors revealed that tolvaptan effectively inhibited the cAMP/PKA and PI3K/AKT signaling pathways. The expression of the proliferative marker proliferating cell nuclear antigen (PCNA) was significantly lower in tumors excised from tolvaptan-treated mice, whereas the expression levels of the apoptotic marker caspase-3 were higher than those in control animals. Furthermore, tumor vascularization was significantly lower in the tolvaptan group. Overall, these findings suggest that tolvaptan counteracts tumor progression in vivo and, if confirmed, might indicate a possible role of this molecule as an adjuvant in anticancer strategies.

Development, validation and application of a UPLC-MS/MS method for simultaneous quantification of OPC-61815 and its metabolites tolvaptan, DM-4103 and DM-4107 in human plasma.

OPC-61815 is an intravenous formulation vasopressin antagonist designed to treat heart failure patients, especially who have difficulty in oral intake. Tolvaptan together with DM-4103 and DM-4107 are considered as the major metabolites of OPC-61815 biotransformed in the liver via cytochrome P450 (CYP) 3A. An efficient and robust ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of OPC-61815 and its three metabolites in human plasma was developed and fully validated. To our best knowledge, it was the first published method that simultaneously quantified all of these four analytes in only one run. Simple and rapid sample preparation procedure and very short UPLC-MS/MS run time (3.5 min) offered OPC-61815 and its metabolites relatively high throughput detection, which was greatly beneficial to further clinical bio-sample analysis. The method showed good linearity and sufficient sensitivity in the range of 2.00-1000 ng/mL with a low limit of quantitation (2.00 ng/mL) for each analyte. For samples with concentrations above 1000 ng/mL, 100-fold dilution with blank plasma before sample preparation was accepted. High precision and accuracy, high selectivity and satisfactory recovery of this method were demonstrated. For all of the four analytes, no significant matrix effect or carry-over was observed. The stability of analytes and internal standards under different conditions were evaluated to ensure they were stable during the whole period of storage, preparation and detection. Also, re-injection reproducibility was investigated. In addition, the conversion test showed that almost no OPC-61815 converted into DM-4103 and DM-4107 during sample processing, while attention should be paid to the concentration difference between OPC-61815 and tolvaptan in bioanalysis. The developed UPLC-MS/MS method was successfully applied to an open, single and multiple dose administration phase I trial for monitoring the pharmacokinetics of OPC-61815. This work provided a promising way for further pharmacokinetic study of OPC-61815.

Impact of Tolvaptan Combined with Low-Dose Dopamine in Heart Failure Patients with Acute Kidney Injury.

The impact of tolvaptan and low-dose dopamine on heart failure (HF) patients with acute kidney injury (AKI) remains uncertain from a clinical standpoint.HF patients with AKI were selected and divided in a 1:1 fashion into the dopamine combined with the tolvaptan group (DTG), the tolvaptan group (TG), and the control group (CG). According to the standard of care, TG received tolvaptan 15 mg orally daily for a week. DTG received combination treatment, including 7 consecutive days of dopamine infusion (2 µg/kg・minutes) and oral tolvaptan 15 mg. Venous blood and urine samples were taken before and after therapy. The primary endpoint was the cardiorenal serological index after 7 days of treatment.Sixty-five patients were chosen randomly for the DTG (22 patients), TG (20 patients), and CG (23 patients), which were similar before the treatment. The serum indexes related to cardiac function (N-terminal probrain natriuretic peptide and cardiac troponin I) in DTG were decreased, compared with TG and CG (P < 0.05). Furthermore, the serological markers of renal function (serum cystatin C, serum creatinine, and neutrophil gelatinase-associated lipocalin) in DTG were lower than those in TG and CG (P < 0.05). There was no significant difference in the incidence of adverse reactions among groups.Low-dose dopamine combined with tolvaptan can markedly improve patients' cardiac and renal function. This may be considered a new therapeutic method for HF patients with AKI.

Clinical efficacy of tolvaptan in acute decompensated heart failure patients with severe aortic stenosis and atrial fibrillation: a sub-analysis from the LOHAS registry.

BACKGROUND: Severe aortic valve stenosis (AS) and atrial fibrillation (AF) are risk factors of hemodynamic instability in heart failure (HF) management due to low cardiac output, respectively. Therefore, the treatment of HF due to severe AS complicated with AF is anticipated to be difficult. Tolvaptan, a vasopressin V2 receptor inhibitor, is effective in controlling acute decompensated heart failure (ADHF) with hemodynamic stability. However, its clinical efficacy against ADHF caused by AS with AF remains to be determined. METHODS: Clinical information (from September 2014 to December 2017) of 59 patients diagnosed with ADHF due to severe AS (20 patients with AF; 39 patients with sinus rhythm [SR]) was obtained from the LOHAS registry. The registry collected data from seven hospitals and assessed the short-term effects of tolvaptan in patients hospitalized for ADHF with severe AS. We attempted to identify clinical differences from baseline up to 4 days, comparing patients with AF (AF group) versus those with SR (SR group). RESULTS: There were no significant differences between the groups in age (83.7 ± 4.5 vs. 85.8 ± 6.9 years, respectively; p = 0.11) and aortic valve area (0.60 [0.46-0.73] vs. 0.56 [0.37-0.70] cm2, respectively; p = 0.50). However, left atrial volume was larger (104 [85-126] vs. 87 [64-103] mL, respectively; p < 0.01), whereas stroke volume was lower (51.6 ± 14.8 vs. 59.0 ± 18.7 mL, respectively; p = 0.08) in the AF group versus the SR group. Body weight decreased daily from baseline up to day 4 in both groups (from 55.4 to 53.2 kg [p < 0.01] and from 53.5 to 51.0 kg [p < 0.01], respectively) without change in heart rate. Notably, the systolic blood pressure decreased slightly in the AF group after 2 days of treatment with tolvaptan. CONCLUSIONS: Short-term treatment with tolvaptan improved HF in patients hospitalized for severe AS, regardless of the presence of AF or SR. After achieving sufficient diuresis, a slight decrease in blood pressure was observed in the AF group, suggesting an appropriate timeframe for safe and effective use of tolvaptan.

Juxtaglomerular apparatus-mediated homeostatic mechanisms: therapeutic implication for chronic kidney disease.

INTRODUCTION: Juxtaglomerular apparatus (JGA)-mediated homeostatic mechanism links to how sodium-glucose cotransporter 2 inhibitors (SGLT2is) slow progression of chronic kidney disease (CKD) and may link to how tolvaptan slows renal function decline in autosomal dominant polycystic kidney disease (ADPKD). AREA COVERED: JGA-mediated homeostatic mechanism has been hypothesized based on investigations of tubuloglomerular feedback and renin-angiotensin system. We reviewed clinical trials of SGLT2is and tolvaptan to assess the relationship between this mechanism and these drugs. EXPERT OPINION: When sodium load to macula densa (MD) increases, MD increases adenosine production, constricting afferent arteriole (Af-art) and protecting glomeruli. Concurrently, MD signaling suppresses renin secretion, increases urinary sodium excretion, and counterbalances reduced sodium filtration. However, when there is marked increase in sodium load per-nephron, as in advanced CKD, MD adenosine production increases, relaxing Af-art and maintaining sodium homeostasis at the expense of glomeruli. The beneficial effects of tolvaptan on renal function in ADPKD may also depend on the JGA-mediated homeostatic mechanisms since tolvaptan inhibits sodium reabsorption in the thick ascending limb.The JGA-mediated homeostatic mechanism regulates Af-arts, constricting to relaxing according to homeostatic needs. Understanding this mechanism may contribute to the development of pharmacotherapeutic compounds and better care for patients with CKD.

Case report: Secondary failure to tolvaptan in a patient with SCLC and paraneoplastic SIADH.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is frequent in lung cancer patients. Here, we report a case with persistent hyponatremia, which suggested malignant SIADH and facilitated an early diagnosis of small cell lung cancer (SCLC). A combined radio-chemotherapy led to a partial remission and resolution of SIADH. An early relapse was indicated by reoccurring severe hyponatremia and increased copeptin levels, which were used as surrogate markers for the antidiuretic hormone (ADH). As palliative immunochemotherapy, together with fluid restriction and solute substitution, were unable to control hyponatremia, treatment with the ADH V2-receptor antagonist tolvaptan was initiated. Over time, the dose of tolvaptan needed to be increased, paralleled by a well-documented exponential increase of copeptin levels. In summary and conclusion, this is a rare case of a secondary failure to tolvaptan with unique documentary evidence of increasing copeptin levels. This observation supports the hypothesis that exceedingly high ADH levels may lead to competitive displacement of tolvaptan from the V2 receptor.

Measured and Estimated Glomerular Filtration Rate to Evaluate Rapid Progression and Changes over Time in Autosomal Polycystic Kidney Disease: Potential Impact on Therapeutic Decision-Making.

Autosomal polycystic kidney disease (ADPKD) is the most common genetic form of kidney failure, reflecting unmet needs in management. Prescription of the only approved treatment (tolvaptan) is limited to persons with rapidly progressing ADPKD. Rapid progression may be diagnosed by assessing glomerular filtration rate (GFR) decline, usually estimated (eGFR) from equations based on serum creatinine (eGFRcr) or cystatin-C (eGFRcys). We have assessed the concordance between eGFR decline and identification of rapid progression (rapid eGFR loss), and measured GFR (mGFR) declines (rapid mGFR loss) using iohexol clearance in 140 adults with ADPKD with ≥3 mGFR and eGFRcr assessments, of which 97 also had eGFRcys assessments. The agreement between mGFR and eGFR decline was poor: mean concordance correlation coefficients (CCCs) between the method declines were low (0.661, range 0.628 to 0.713), and Bland and Altman limits of agreement between eGFR and mGFR declines were wide. CCC was lower for eGFRcys. From a practical point of view, creatinine-based formulas failed to detect rapid mGFR loss (-3 mL/min/y or faster) in around 37% of the cases. Moreover, formulas falsely indicated around 40% of the cases with moderate or stable decline as rapid progressors. The reliability of formulas in detecting real mGFR decline was lower in the non-rapid-progressors group with respect to that in rapid-progressor patients. The performance of eGFRcys and eGFRcr-cys equations was even worse. In conclusion, eGFR decline may misrepresent mGFR decline in ADPKD in a significant percentage of patients, potentially misclassifying them as progressors or non-progressors and impacting decisions of initiation of tolvaptan therapy.

Long-term effectiveness and safety of tolvaptan in autosomal dominant polycystic kidney disease.

BACKGROUND AND OBJECTIVES: Evidence on the long-term use of tolvaptan in autosomal dominant polycystic kidney disease (ADPKD) is limited. The aim was to evaluate the tolvaptan effectiveness and safety in real clinical setting. MATERIAL AND METHODS: A single-center observational study (2016-2022) involving ADPKD patients treated with tolvaptan was conducted. Annual change in serum creatinine (sCr) and estimated glomerular filtration rate (eGFR) before and after treatment initiation were evaluated. Change in total kidney volume (TKV), blood pressure (BP) and urinary albuminuria at 12, 24 and 36 months after initiation were also determined. Adverse events (AEs) according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 were analyzed. RESULTS: A total of 22 patients were included. No significant differences pre- vs post tolvaptan treatment in annual rate of change in eGFR (-3.52ml/min/1.73m2 [-4.98%] vs -3.98ml/min/1.73m2 [-8.48%], p=0.121) and sCr (+0.06mg/dL [4.22%] vs +0.15mg/dL [7.77%], p=0.429) were observed. Tolvaptan improved urinary osmolality at 12 (p=0.019) and 24 months (p=0.008), but not at 36 months (p=0.11). There were no changes in TKV, BP control and urinary albuminuria at 12, 24 or 36 months. A worse response was shown in patients with rapid kidney function decline (p=0.042). A 36.4% of the patients developed grade III/IV AEs. A 22.7% discontinued treatment due to unacceptable toxicity. CONCLUSIONS: This study shows a modest benefit of tolvaptan in ADPKD patients, as well as safety concerns.

Tolvaptan therapy for edema in patients with chronic kidney disease.

OBJECTIVE: Tolvaptan is a vasopressin V2 receptor antagonist that is commonly prescribed to alleviate edema associated with renal diseases. However, the clinical benefits of tolvaptan in chronic kidney disease (CKD) remain unclear. This study aimed to evaluate the effectiveness of tolvaptan in managing edema caused by CKD. MATERIALS AND METHODS: The efficacy and treatment regimen of tolvaptan were assessed in a cohort of 96 patients with renal edema and CKD. During the treatment, the patients' creatinine (CR), uric acid (UA), and estimated glomerular filtration rate (eGFR) were monitored as important indicators of kidney function. Coagulation-associated molecules including fibrinogen, D-dimer, and fibrin degradation products (FDPs) were measured. Electrolyte disorders and acute kidney injury were closely monitored. Tolvaptan was administered at a daily dose of 7.5 mg, and 30 mg of edoxaban was administered to manage deep vein thrombosis. RESULTS: During the course of tolvaptan therapy, the eGFR of the patients was not declined. Edema was eliminated in 82.18% of patients. Proteinuria was reduced in the patients (p < 0.05). There were no significant changes in serum sodium levels throughout treatment, and no significant difference was observed in blood volume between the end of treatment and baseline levels. Importantly, acute kidney injury did not occur, and renal edema and deep vein thrombosis were successfully treated. CONCLUSION: As long as a rational treatment regimen is followed, tolvaptan is a safe and effective diuretic for treating edema in CKD, even in the late stages of CKD without reducing residual renal function in the patients.

Long-Residence Time Peptide Antagonist for the Vasopressin V2 Receptor to Treat Autosomal Dominant Polycystic Kidney Disease.

The dysregulated intracellular cAMP in the kidneys drives cystogenesis and progression in autosomal dominant polycystic kidney disease (ADPKD). Mounting evidence supports that vasopressin V2 receptor (V2R) antagonism effectively reduces cAMP levels, validating this receptor as a therapeutic target. Tolvaptan, an FDA-approved V2R antagonist, shows limitations in its clinical efficacy for ADPKD treatment. Therefore, the pursuit of better-in-class V2R antagonists with an improved efficacy remains pressing. Herein, we synthesized a set of peptide V2R antagonists. Peptide 33 exhibited a high binding affinity for the V2R (Ki = 6.1 ± 1.5 nM) and an extended residence time of 20 ± 1 min, 2-fold that of tolvaptan. This prolonged interaction translated into sustained suppression of cAMP production in washout experiments. Furthermore, peptide 33 exhibited improved efficacies over tolvaptan in both ex vivo and in vivo models of ADPKD, underscoring its potential as a promising lead compound for the treatment of ADPKD.

Renal ultrasonography predicts worsening renal function in patients with heart failure under tolvaptan administration.

AIMS: Renal dysfunction in patients with chronic heart failure predicts a poor prognosis. Tolvaptan has a diuretic effect in patients with chronic kidney disease and heart failure without adverse effects on renal function. We aimed to determine the effects of tolvaptan and predictors of worsening renal function in patients with heart failure. METHODS AND RESULTS: This post hoc analysis was a sub-analysis of a single-centre prospectively randomized trial on the early and short-term tolvaptan administration. We enrolled 201 participants with decompensated heart failure between January 2014 and March 2019 (early group, n = 104; age: 79.0 ± 12.8 years; late group, n = 97; age: 80.3 ± 10.8 years). Renal ultrasonography was performed before and after the administration of tolvaptan. Urine output and oral water intake significantly increased during tolvaptan administration. The difference between water intake and urine volume increased during tolvaptan administration. Changes in body weight, blood pressure, heart rate, and estimated glomerular filtration rate (eGFR) in both groups were comparable. The changes in peak-systolic velocity (PSV), acceleration time (AT) of the renal arteries, and resistance index were comparable. The changes in PSV and end-diastolic velocity (EDV) of the interlobar arteries increased following tolvaptan administration (Δmax PSV: 0.0 ± 14.8 cm/s before tolvaptan vs. 5.6 ± 15.7 cm/s after tolvaptan, P = 0.002; Δmean PSV: 0.4 ± 12.3 vs. 4.9 ± 12.7 cm/s, P = 0.002; Δmax EDV: -0.2 ± 3.5 vs. 1.4 ± 4.0 cm/s, P = 0.001; Δmean EDV: -0.0 ± 3.1 vs. 1.1 ± 3.4 cm/s, P = 0.003). The renal artery AT was negatively correlated with the eGFR (Δmax AT: beta = -0.2354, P = 0.044; Δmean AT: beta = -0.2477, P = 0.035). CONCLUSIONS: Tolvaptan increased the PSV and EDV of the interlobar artery, which may mean tolvaptan increased renal blood flow. The renal artery AT may be a surrogate for worsening renal function.

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.

HYDROchlorothiazide versus placebo to PROTECT polycystic kidney disease patients and improve their quality of life: study protocol and rationale for the HYDRO-PROTECT randomized controlled trial.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) leads to progressive renal cyst formation and loss of kidney function in most patients. Vasopressin 2 receptor antagonists (V2RA) like tolvaptan are currently the only available renoprotective agents for rapidly progressive ADPKD. However, aquaretic side effects substantially limit their tolerability and therapeutic potential. In a preliminary clinical study, the addition of hydrochlorothiazide (HCT) to tolvaptan decreased 24-h urinary volume and appeared to increase renoprotective efficacy. The HYDRO-PROTECT study will investigate the long-term effect of co-treatment with HCT on tolvaptan efficacy (rate of kidney function decline) and tolerability (aquaresis and quality of life) in patients with ADPKD. METHODS: The HYDRO-PROTECT study is an investigator-initiated, multicenter, double-blind, placebo-controlled, randomized clinical trial. The study is powered to enroll 300 rapidly progressive patients with ADPKD aged ≥ 18 years, with an eGFR of > 25 mL/min/1.73 m2, and on stable treatment with the highest tolerated dose of tolvaptan in routine clinical care. Patients will be randomly assigned (1:1) to daily oral HCT 25 mg or matching placebo treatment for 156 weeks, in addition to standard care. OUTCOMES: The primary study outcome is the rate of kidney function decline (expressed as eGFR slope, in mL/min/1.73 m2 per year) in HCT versus placebo-treated patients, calculated by linear mixed model analysis using all available creatinine values from week 12 until the end of treatment. Secondary outcomes include changes in quality-of-life questionnaire scores (TIPS, ADPKD-UIS, EQ-5D-5L, SF-12) and changes in 24-h urine volume. CONCLUSION: The HYDRO-PROTECT study will demonstrate whether co-treatment with HCT can improve the renoprotective efficacy and tolerability of tolvaptan in patients with ADPKD.

Long-Term Effects of Tolvaptan in Autosomal Dominant Polycystic Kidney Disease: Predictors of Treatment Response and Safety over 6 Years of Continuous Therapy.

Tolvaptan, an oral vasopressin V2 receptor antagonist, reduces renal volume expansion and loss of renal function in patients with autosomal dominant polycystic kidney disease (ADPKD). Data for predictive factors indicating patients more likely to benefit from long-term tolvaptan are lacking. Data were retrospectively collected from 55 patients on tolvaptan for 6 years. Changes in renal function, progression of renal dysfunction (estimated glomerular filtration rate [eGFR], 1-year change in eGFR [ΔeGFR/year]), and renal volume (total kidney volume [TKV], percentage 1-year change in TKV [ΔTKV%/year]) were evaluated at 3-years pre-tolvaptan, at baseline, and at 6 years. In 76.4% of patients, ΔeGFR/year improved at 6 years. The average 6-year ΔeGFR/year (range) minus baseline ΔeGFR/year: 3.024 (-8.77-20.58 mL/min/1.73 m2). The increase in TKV was reduced for the first 3 years. A higher BMI was associated with less of an improvement in ΔeGFR (p = 0.027), and family history was associated with more of an improvement in ΔeGFR (p = 0.044). Hypernatremia was generally mild; 3 patients had moderate-to-severe hyponatremia due to prolonged, excessive water intake in response to water diuresis-a side effect of tolvaptan. Family history of ADPKD and baseline BMI were contributing factors for ΔeGFR/year improvement on tolvaptan. Hyponatremia should be monitored with long-term tolvaptan administration.

Evaluation of the Renal and Cardiovascular Effects of Long-Term Tolvaptan Treatment in Autosomal Dominant Polycystic Kidney Disease.

INTRODUCTION: Cardiovascular diseases constitute a significant cause of morbidity and mortality in individuals with autosomal dominant polycystic kidney disease (ADPKD). This study aimed to assess the long-term effects of tolvaptan on the kidneys and heart in rapidly progressing ADPKD. METHODS: Among 354 patients diagnosed with ADPKD, 58 meeting the eligibility criteria for tolvaptan were included in the study. The study comprised two groups with similar demographic and clinical characteristics: 29 patients receiving tolvaptan treatment and 29 in the control group. Several included genetic analysis, magnetic resonance imaging, and echocardiography. Clinical and cardiac changes were recorded in both groups after a 3-year follow-up. RESULTS: Tolvaptan treatment demonstrated a significant reduction in the rate of eGFR decline compared to the control group. Furthermore, it was observed that tolvaptan could prevent the development of cardiac arrhythmias by inhibiting an increase in QTc interval and heart rate. CONCLUSION: These findings suggest that, in addition to slowing kidney progression in ADPKD management, tolvaptan may potentially benefit in preventing cardiac complications.

The syndrome of inappropriate antidiuretic hormone associated with nasal and paranasal malignant tumors.

PURPOSE: To investigate the clinical characteristics of the syndrome of inappropriate antidiuretic hormone (SIADH) associated with nasal and paranasal malignant tumors. METHODS: Patients with locally advanced or recurrence/metastatic malignant tumors of the nasal and paranasal sinuses were included. The SIADH was diagnosed according to the diagnostic criteria. The clinical characteristics of SIADH patients were retrospectively analyzed. RESULTS: Six patients (6/188, 3.2%) met the diagnostic criteria of SIADH, including four olfactory neuroblastoma (4/26, 15.4%), one neuroendocrine carcinoma (1/9, 11.1%), and one squamous cell carcinoma (1/63, 1.6%). Five patients (83.3%) had severe hyponatremia; however, the hyponatremia could be improved by fluid restriction or tolvaptan. Three patients' SIADH were recovered during the chemotherapy and the other three were recovered after the surgery. CONCLUSION: The incidence of SIADH associated with nasal and paranasal malignant tumors is relatively more common in olfactory neuroblastoma and neuroendocrine carcinoma. The hyponatremia caused by SIADH may be corrected by fluid restriction or tolvaptan, and the SIADH may be recovered through anti-tumor therapy.