Clinical Pharmacology for Jynarque
Mechanism Of Action
Tolvaptan is a selective vasopressin V2-receptor antagonist with an affinity for the V2-receptor that is 1.8 times that of native arginine vasopressin (AVP). Tolvaptan affinity for the V2-receptor is 29 times that for the V1a-receptor. Decreased binding of vasopressin to the V2-receptor in the kidney lowers adenylate cyclase activity resulting in a decrease in intracellular adenosine 3', 5'-cyclic monophosphate (cAMP) concentrations. Decreased cAMP concentrations prevent aquaporin 2 containing vesicles from fusing with the plasma membrane, which in turn causes an increase in urine water excretion, an increase in free water clearance (aquaresis) and a decrease in urine osmolality. In human ADPKD cyst epithelial cells, tolvaptan inhibited AVP-stimulated in vitro cyst growth and chloride-dependent fluid secretion into cysts. In animal models, decreased cAMP concentrations were associated with decreases in the rate of growth of total kidney volume and the rate of formation and enlargement of kidney cysts. Tolvaptan metabolites have no or weak antagonist activity for human V2-receptors compared with tolvaptan.
Pharmacodynamics
In healthy subjects or patients with eGFRs as low as 10 mL/min/1.73 m² receiving a single dose of tolvaptan, the onset of the aquaretic effects occurs within 1 to 2 hours post-dose. In healthy subjects, single doses of 60 mg and 90 mg produce a peak effect of about a 9 mL/min increase in urine excretion rate is observed between 4 and 8 hours post-dose. Higher doses of tolvaptan do not increase the peak effect in urine excretion rate but sustain the effect for a longer period of time.
Urine excretion rate returns to baseline within 24 hours following the maximum recommended 90 mg dose of tolvaptan.
Changes in free water clearance mirror the changes in urine excretion rate. Increased free water clearance causes an increase in serum sodium concentration unless fluid intake is increased to match urine output.
Increases in urine excretion rate and free water clearance are positively correlated with baseline glomerular filtration rate with increases in both values observed in patients with creatinine clearance as low as 15 mL/min.
With the recommended split-dose regimens, tolvaptan inhibits vasopressin from binding to the V2-receptor in the kidney for the entire day, as indicated by increased urine output and decreased urine osmolality. Following a 90/30 mg split-dose regimen in patients with eGFR >60 mL/min/1.73 m², the change in mean daily urine volume was about 4 L for a mean total daily volume of about 7 L. In patients with eGFR <30 mL/min/1.73 m², the mean change in daily urine volume was about 2 L for a total daily urine volume of about 5 L.
Plasma concentrations of native AVP may increase (avg. 2 to 9 pg/mL) with tolvaptan treatment and return to baseline levels when treatment is stopped.
During tolvaptan treatment, small changes in renal function are expected and the changes are independent of baseline renal function. Glomerular filtration rate is decreased about 6% to 10% and uric acid clearance is decreased about 20% to 25%. Percent changes in renal plasma flow are highly correlated to percent changes in GFR. These changes are reversed upon discontinuation of tolvaptan.
Cardiac Electrophysiology
No prolongation of the QT interval was observed with tolvaptan following multiple doses of 300 mg/day for 5 days.
Pharmacokinetics
In healthy subjects, the pharmacokinetics of tolvaptan after single doses of up to 480 mg and multiple doses up to 300 mg once daily have been studied. In ADPKD patients, single doses up to 120 mg and multiple split-doses up to 90/30 mg have been studied.
Absorption
In healthy subjects, peak concentrations of tolvaptan are observed between 2 and 4 hours post-dose. Peak concentrations increase less than dose proportionally with doses greater than 240 mg.
The absolute bioavailability of tolvaptan decreases with increasing doses. The absolute bioavailability of tolvaptan following an oral dose of 30 mg is 56% (range 42% to 80%).
Co-administration of 90 mg JYNARQUE with a high-fat meal (~1000 calories, of which 50% are from fat) doubles peak concentrations but has no effect on the AUC of tolvaptan; tolvaptan may be administered with or without food.
Distribution
Tolvaptan binds to both albumin and α1-acid glycoprotein and the overall protein binding is >98%; binding is not affected by disease state. The volume of distribution of tolvaptan is about 3 L/kg. The pharmacokinetic properties of tolvaptan are stereospecific, with a steady-state ratio of the S-(-) to the R-(+) enantiomer of about 3. When administered as multiple once-daily 300 mg doses to healthy subjects or as split-dose regimens to patients with ADPKD, tolvaptan's accumulation factor is <1.2. There is marked inter-subject variation in peak and average exposure to tolvaptan with a percent coefficient of variation ranging between 30% and 60%.
Metabolism And Elimination
Tolvaptan is metabolized almost exclusively by CYP3A. Fourteen metabolites have been identified in plasma, urine and feces; all but one were also metabolized by CYP3A and none are pharmacodynamically active. After oral administration of radiolabeled tolvaptan, tolvaptan was a minor component in plasma representing 3% of total plasma radioactivity; the oxobutyric acid metabolite was present at 52.5% of total plasma radioactivity with all other metabolites present at lower concentrations than tolvaptan. The oxobutyric acid metabolite shows a plasma half-life of ~180 h. About 40% of radioactivity was recovered in urine (<1% as unchanged tolvaptan) and 59% in feces (19% as unchanged tolvaptan). Following intravenous infusion, tolvaptan half-life is approximately 3 hours. Following single oral doses to healthy subjects, the estimated half-life of tolvaptan increases from 3 hours for a 15 mg dose to approximately 12 hours for 120 mg and higher doses due to more prolonged absorption of tolvaptan at higher doses; apparent clearance is approximately 4 mL/min/kg and does not appear to change with increasing dose.
Specific Populations
Age, Gender And Race
Age, gender and race have no effect on tolvaptan pharmacokinetics.
Hepatic Impairment
In studies involving patients with hepatic impairment (Child-Pugh class A-C), but without ADPKD; moderate (class A, B) or severe (class C) hepatic impairment decreases the clearance and increases the volume of distribution of tolvaptan.
Renal Impairment
In subjects with creatinine clearances ranging from 10 to 124 mL/min administered a single dose of 60 mg tolvaptan, the AUC and Cmax of plasma tolvaptan was increased 90% and 10%, respectively, for subjects with clearances of <30 mL/min compared to subjects with clearances >60 mL/min [see Use In Special Populations].
In ADPKD patients with estimated creatinine clearance >60 mL/min, pharmacokinetics were similar to healthy subjects.
Drug Interaction Studies
Impact Of Other Drugs On Tolvaptan
Strong CYP3A Inhibitors
Tolvaptan's Cmax and AUC were, respectively, 3.5 times and 5.4 times as high following ketoconazole 200 mg given one day prior to and concomitantly with 30 mg tolvaptan.
Moderate CYP3A4 Inhibitors
Fluconazole: Fluconazole 400 mg given one day prior, and 200 mg given concomitantly, produced an 80% and 200% increase in tolvaptan Cmax and AUC, respectively.
Grapefruit Juice: When 60 mg tolvaptan was taken with 240 mL regular strength grapefruit juice, tolvaptan Cmax and AUC increased 90% and 60%, respectively.
CYP3A Inducers
Rifampin: Rifampin 600 mg once daily for 7 days followed by a single 240 mg dose of tolvaptan decreased both tolvaptan Cmax and AUC about 85%.
Other Drugs
Co-administration of lovastatin, digoxin, furosemide, and hydrochlorothiazide with tolvaptan has no clinically relevant impact on the exposure to tolvaptan.
Impact Of Tolvaptan On Other Drugs
CYP3A Substrates
Co-administration of lovastatin and tolvaptan increases the AUC of lovastatin and its active metabolite lovastatin-β hydroxy acid by 40% and 30%, respectively. These are non-clinically significant increases in exposure.
P-gp Substrates
Digoxin: Digoxin 0.25 mg was administered once daily for 12 days. Tolvaptan 60 mg, was co-administered once daily on Days 8 to 12. Digoxin Cmax and AUC were increased 30% and 20%, respectively.
Transporter Substrates
Tolvaptan is a substrate of P-gp and an inhibitor of P-gp and BCRP. The oxobutyric acid metabolite of tolvaptan is an inhibitor of OATP1B1 and OAT3. Co-administration of tolvaptan with rosuvastatin (BCRP substrate) did not have a clinically significant effect on rosuvastatin exposure. Rosuvastatin Cmax and AUCt increased 54% and 69%, respectively.
Administration of rosuvastatin (OATP1B1 substrate) or furosemide (OAT3 substrate) to healthy subjects with elevated oxobutyric acid metabolite plasma concentrations did not meaningfully alter the pharmacokinetics of rosuvastatin or furosemide.
Other Drugs
Co-administration of tolvaptan did not meaningfully alter the pharmacokinetics of warfarin, furosemide, hydrochlorothiazide, or amiodarone (or its active metabolite, desethylamiodarone).
Clinical Studies
JYNARQUE was shown to slow the rate of decline in renal function in adult patients at risk of rapidly progressing ADPKD in two trials: TEMPO 3:4 in patients at earlier stages of disease and REPRISE in patients at later stages. The findings from these trials, when taken together, suggest that JYNARQUE slows the loss of renal function progressively through the course of the disease.
TEMPO 3:4: A Phase 3, Double-Blind, Placebo-Controlled, Randomized Trial In Early, Rapidly-Progressing ADPKD
In TEMPO 3:4 (NCT00428948), 1445 adult patients (age >18 years) with early (estimated creatinine clearance [eCrCl] ≥60 mL/min), rapidly-progressing (total kidney volume [TKV] ≥750 mL and age <51 years) ADPKD (diagnosed by modified Ravine criteria) were randomized 2:1 to treatment with tolvaptan or placebo. Patients were treated for up to 3 years; patients who discontinued medication prematurely were only required to attend clinic visits to assess renal function for up to 42 days after treatment withdrawal and to attend telephone visits at all scheduled visits for up to 36 months. Patients who completed treatment at the 3-year visit had treatment interrupted for 2 to 6 weeks to assess renal function post treatment. Patients received treatment twice a day (first dose on waking, second dose approximately 9 hours later). Patients were initiated on 45 mg/15 mg, and up-titrated weekly to 60 mg/30 mg and then to 90 mg/30 mg as tolerated. Patients were to maintain the highest tolerated dose for 3 years, but could interrupt, decrease and/or increase as clinical circumstances warranted within the range of titrated doses. All patients were encouraged to drink adequate water to avoid thirst or dehydration and before bedtime.
The primary endpoint was the intergroup difference for rate of change of TKV normalized as a percentage. The key secondary composite endpoint (ADPKD progression) was time to multiple clinical progression events of: 1) worsening kidney function (defined as a persistent 25% reduction in reciprocal serum creatinine during treatment from end of titration to last on-drug visit); 2) medically significant kidney pain (defined as requiring prescribed leave, last-resort analgesics, narcotic and anti-nociceptive, radiologic or surgical interventions); 3) worsening hypertension (defined as a persistent increase in blood pressure category or an increased anti-hypertensive prescription); 4) worsening albuminuria (defined as a persistent increase in albumin/creatinine ratio category).
At baseline, average estimated glomerular filtration rate (eGFR) was 82 mL/min/1.73 m² (CKD-Epidemiology formula) and mean TKV was 1692 mL (height adjusted 972 mL/m). Approximately 35% had an eGFR of 90 mL/min/1.73 m² or greater, 48% had an eGFR between 60 to 89 mL/min/1.73 m², 14% had an eGFR of 45 to 60 mL/min/1.73 m², and 3% had an eGFR of <45 mL/min/1.73 m². The subjects' mean age was 39 years, 48% were female, 84% were Caucasian, 13% were Asian, and 1.7% were Black or African-American. Approximately 80% had hypertension and approximately 71% were taking an agent that acts on the renin-angiotensin system. Of the 770 subjects who submitted to genetic analysis in TEMPO 3:4's open-label extension, 749 (97%) had an identifiable mutation in the PKD1 (656 or 88%), or PKD2 (93 or 12%) gene.
The trial met its prespecified primary endpoint of 3-year change in TKV (p<0.0001). The difference in TKV between treatment groups mostly developed within the first year, the earliest assessment, with little further difference in years two and three. In Years 4 and 5 during the TEMPO 3:4 extension trial, both groups received JYNARQUE and the difference between the groups in TKV was not maintained. Tolvaptan has little effect on kidney size beyond what accrues during the first year of treatment.
The relative rate of ADPKD-related events was decreased by 13.5% in tolvaptan-treated patients, (44 vs. 50 events per 100 person-years; hazard ratio, 0.87; 95% CI, 0.78 to 0.97; p=0.0095). As shown in the table below, the result of the key secondary composite endpoint was driven by effects on worsening kidney function and kidney pain events. In contrast, there was no effect of tolvaptan on either progression of hypertension or albuminuria. Few subjects in either arm required a radiologic or surgical intervention for kidney pain. Most kidney pain events reflected use of a medication to treat pain such as use of paracetamol, tricyclic antidepressants, narcotics and other non-narcotic agents.
| Event |
Tolvaptan |
Placebo |
Hazard Ratio, 95% CI |
| Total Number of Events (Events per 100 person-years) |
Number of Subjects with an Event (percentage) |
Total Number of Events (Events per 100 person-years) |
Number of Subjects with an Event (percentage) |
| Composite |
1049 (43.9) |
572 (59.5) |
665 (50.0) |
341 (70.6) |
0.87 (0.78,0.97) |
| Worsening Kidney Function |
44 (1.9) |
42 (4.6) |
64 (4.8) |
61 (12.8) |
0.39 (0.26,0.57) |
| Kidney Pain |
113 (4.7) |
95 (9.9) |
97 (7.3) |
78 (16.2) |
0.64 (0.47,0.89) |
| Onset or Progression of Hypertension |
734 (30.7) |
426 (44.3) |
426 (32.1) |
244 (50.5) |
0.94 (0.81,1.09) |
| Worsening Albuminuria |
195 (8.2) |
195 (20.3) |
103 (7.8) |
101 (20.9) |
1.04 (0.84,1.28) |
The third endpoint (kidney function slope) was assessed as slope of eGFR during treatment (from end of titration to last on-drug visit). The estimated difference in the annual rate of change in those who contributed to the analysis was 1.0 mL/min/1.73 m²/year with a 95% confidence interval of (0.6, 1.4). Of the subjects enrolled in the trial, 5% of subjects in the tolvaptan arm and 2% in the placebo arm either had missing baseline data or discontinued from treatment prior to the end of the titration visit and hence were excluded from the analysis. In the extension trial, eGFR differences produced by the third year of the TEMPO 3:4 trial were maintained over the next 2 years of JYNARQUE treatment.
The efficacy profile was generally consistent across subgroups of interest for this indication; few Black or African-American patients were enrolled in the trial.
REPRISE: A Phase 3, Double-Blind, Placebo-Controlled, Randomized Withdrawal Trial In Later-Stage ADPKD
REPRISE (NCT02160145) was a double-blind, placebo-controlled randomized withdrawal trial in adult patients (age 18 to 65 years) with chronic kidney disease (CKD) with an eGFR between 25 and 65 mL/min/1.73 m² if younger than age 56 years, or eGFR between 25 and 44 mL/min/1.73 m², plus eGFR decline >2.0 mL/min/1.73 m²/year if between age 56 to 65 years. Subjects were to be treated for 12 months; after completion of treatment, patients entered a 3-week follow-up period to assess renal function. The primary endpoint was the treatment difference in the change of eGFR from pre-treatment baseline to post-treatment follow-up, annualized by dividing by each subject's treatment duration.
Prior to randomization, patients were required to complete sequential single-blind run-in periods during which they received placebo for 1 week, followed by tolvaptan titration for 2 weeks, and then treatment with tolvaptan at the highest tolerated dose achieved during titration for 3 weeks. During the titration period, tolvaptan was up-titrated every 3 to 4 days from a daily oral dose of 30 mg/15 mg to 45 mg/15 mg, 60 mg/30 mg and up to a maximum dose of 90 mg/30 mg. Only patients who could tolerate the two highest doses of tolvaptan (60 mg/30 mg or 90 mg/30 mg) for the subsequent 3 weeks were randomized 1:1 to treatment with tolvaptan or placebo.
Patients were maintained on their highest tolerated dose for a period of 12 months but could interrupt, decrease and/or increase as clinical circumstances warranted within the range of titrated doses. All patients were encouraged to start drinking an adequate amount of water at screening and continuing through the end of the trial to avoid thirst or dehydration.
A total of 1519 subjects were enrolled in the study. Of these, 1370 subjects successfully completed the pre-randomization period and were randomized and treated during the 12-month double-blind period. Because 57 subjects did not complete the off-treatment follow-up period, 1313 subjects were included in the primary efficacy analysis.
For subjects randomized, the baseline, average estimated glomerular filtration rate (eGFR) was 41 mL/min/1.73 m² (CKD-Epidemiology formula) and historical TKV, available in 318 (23%) of subjects, averaged 2026 mL. Approximately 5%, 75% and 20% had an eGFR 60 mL/min/1.73 m² or greater, between 30 to 59 mL/min/1.73 m², and between 25 and 29 mL/min/1.73 m², respectively. The subjects' mean age was 47 years, 50% were female, 92% were Caucasian, 4% Black or African-American and 3% were Asian, 93% had hypertension, and 87% of subjects were taking antihypertensive agents affecting the angiotensin converting enzyme or receptor. Of the 115 (8%) of subjects who had prior genetic tests, only 54 (47%) knew their results with 48 (89%) of these having PKD1 and 6 (11%) having PKD2 mutations.
In the randomized period, the change of eGFR from pretreatment baseline to post-treatment follow-up was -2.3 mL/min/1.73 m²/year with tolvaptan as compared with -3.6 mL/min/1.73 m²/year with placebo, corresponding to a treatment effect of 1.3 mL/min/1.73 m²/year (p <0.0001). The key secondary endpoint (eGFR slope in ml/min/1.73 m²/year assessed using a linear mixed effect model of annualized eGFR (CKD-EPI)) showed a difference between treatment groups of 1.0 ml/min/ m²/year that was also statistically significant (p < 0.0001).
The efficacy profile was generally consistent across subgroups of interest for this indication; few Black or African-American patients were enrolled in the trial.