Clinical Pharmacology for Qtern
Mechanism Of Action
Dapagliflozin
Sodium-glucose cotransporter 2 (SGLT2), expressed in the proximal renal tubules, is responsible for the majority of the reabsorption of filtered glucose from the tubular lumen. Dapagliflozin is an inhibitor of SGLT2. By inhibiting SGLT2, dapagliflozin reduces reabsorption of filtered glucose and thereby promotes urinary glucose excretion.
Saxagliptin
Increased concentrations of the incretin hormones such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are released into the bloodstream from the small intestine in response to meals. These hormones cause insulin release from the pancreatic beta cells in a glucose-dependent manner but are inactivated by the DPP-4 enzyme within minutes. GLP-1 also lowers glucagon secretion from pancreatic alpha cells, reducing hepatic glucose production. In patients with type 2 diabetes mellitus, concentrations of GLP-1 are reduced but the insulin response to GLP-1 is preserved. Saxagliptin is a competitive DPP-4 inhibitor that slows the inactivation of the incretin hormones, thereby increasing their bloodstream concentrations and reducing fasting and postprandial glucose concentrations in a glucose-dependent manner in patients with type 2 diabetes mellitus.
Pharmacodynamics
Dapagliflozin
Increases in the amount of glucose excreted in the urine were observed in healthy subjects and in patients with type 2 diabetes mellitus following the administration of dapagliflozin. Dapagliflozin dose of 5 or 10 mg per day in patients with type 2 diabetes mellitus for 12 weeks resulted in excretion of approximately 70 grams of glucose in the urine per day at Week 12. A near maximum glucose excretion was observed at the dapagliflozin daily dose of 20 mg. This urinary glucose excretion with dapagliflozin also results in increases in urinary volume [see ADVERSE REACTIONS]. After discontinuation of dapagliflozin, on average, the elevation in urinary glucose excretion approaches baseline by about 3 days from discontinuation for the 10 mg dose.
Figure 1: Scatter Plot and Fitted Line of Change from Baseline in 24-Hour Urinary Glucose Amount versus Dapagliflozin Dose in Healthy Subjects and Subjects with Type 2 Diabetes Mellitus (T2DM) (Semi-Log Plot)
Saxagliptin
In patients with type 2 diabetes mellitus, administration of saxagliptin inhibits DPP-4 enzyme activity for a 24-hour period. After an oral glucose load or a meal, this DPP-4 inhibition resulted in a 2-to 3-fold increase in circulating levels of active GLP-1 and GIP, decreased glucagon concentrations, and increased glucose-dependent insulin secretion from pancreatic beta cells. The rise in insulin and decrease in glucagon were associated with lower fasting glucose concentrations and reduced glucose excursion following an oral glucose load or a meal.
Cardiac Electrophysiology
Dapagliflozin
Dapagliflozin was not associated with clinically meaningful prolongation of QTc interval at daily doses up to 150 mg (15-times the recommended maximum dose) in a study of healthy subjects. In addition, no clinically meaningful effect on QTc interval was observed following single doses of up to 500 mg (50-times the recommended maximum daily dose) of dapagliflozin in healthy subjects.
Saxagliptin
In a randomized, double-blind, placebo-controlled, 4-way crossover, active comparator study using moxifloxacin in 40 healthy subjects, saxagliptin was not associated with clinically meaningful prolongation of the QTc interval or heart rate at daily doses up to 40 mg (8-times the recommended maximum daily dose).
Pharmacokinetics
Overall, the pharmacokinetics of dapagliflozin and saxagliptin were not affected in a clinically relevant manner when administered as QTERN.
Saxagliptin
The pharmacokinetics of saxagliptin and its active metabolite, 5-hydroxy saxagliptin, were similar in healthy subjects and in patients with type 2 diabetes mellitus. The Cmax and AUC values of saxagliptin and its active metabolite increased proportionally in the 2.5 to 400 mg dose range. Following a 5 mg single oral dose of saxagliptin to healthy subjects, the mean plasma AUC values for saxagliptin and its active metabolite were 78 ng•h/mL and 214 ng•h/mL, respectively. The corresponding plasma Cmax values were 24 ng/mL and 47 ng/mL, respectively. The average variability (%CV) for AUC and Cmax for both saxagliptin and its active metabolite was less than 25%.
No appreciable accumulation of either saxagliptin or its active metabolite was observed with repeated once daily dosing at any dose level. No dose-and time-dependence were observed in the clearance of saxagliptin and its active metabolite over 14 days of once daily dosing with saxagliptin at doses ranging from 2.5 to 400 mg.
Absorption
Dapagliflozin
Following oral administration of dapagliflozin, the maximum plasma concentration (Cmax) is usually attained within 2 hours under fasting state. The Cmax and AUC values increase dose proportionally with increase in dapagliflozin dose in the therapeutic dose range. The absolute oral bioavailability of dapagliflozin following the administration of a 10 mg dose is 78%. Administration of dapagliflozin with a high-fat meal decreases its Cmax by up to 50% and prolongs Tmax by approximately 1 hour but does not alter AUC as compared with the fasted state.
Saxagliptin
The median time to maximum concentration (Tmax) following the 5 mg once daily dose was 2 hours for saxagliptin and 4 hours for its active metabolite. Administration with a high-fat meal resulted in an increase in Tmax of saxagliptin by approximately 20 minutes as compared to fasted conditions. There was a 27% increase in the AUC of saxagliptin when given with a meal as compared to fasted conditions.
Distribution
Dapagliflozin
Dapagliflozin is approximately 91% protein bound. Protein binding is not altered in patients with renal or hepatic impairment.
Saxagliptin
The in vitro protein binding of saxagliptin and its active metabolite in human serum is negligible. Therefore, changes in blood protein levels in various disease states (e.g., renal or hepatic impairment) are not expected to alter the disposition of saxagliptin.
Metabolism
Dapagliflozin
The metabolism of dapagliflozin is primarily mediated by UGT1A9; CYP-mediated metabolism is a minor clearance pathway in humans. Dapagliflozin is extensively metabolized, primarily to yield dapagliflozin 3-O-glucuronide, which is an inactive metabolite. Dapagliflozin 3-O-glucuronide accounted for 61% of a 50 mg [14C]-dapagliflozin dose and is the predominant drug-related component in human plasma.
Saxagliptin
The metabolism of saxagliptin is primarily mediated by cytochrome P450 3A4/5 (CYP3A4/5). The major metabolite of saxagliptin is also a DPP-4 inhibitor, which is one-half as potent as saxagliptin. Therefore, strong CYP3A4/5 inhibitors and inducers will alter the pharmacokinetics of saxagliptin and its active metabolite [see DRUG INTERACTIONS].
Elimination
Dapagliflozin
Dapagliflozin and related metabolites are primarily eliminated via the renal pathway. Following a single 50 mg dose of [14C]-dapagliflozin, 75% and 21% total radioactivity is excreted in urine and feces, respectively. In urine, less than 2% of the dose is excreted as parent drug. In feces, approximately 15% of the dose is excreted as parent drug. The mean plasma terminal half-life (t½) for dapagliflozin is approximately 12.9 hours following a single oral dose of dapagliflozin 10 mg.
Saxagliptin
Saxagliptin is eliminated by both renal and hepatic pathways. Following a single 50 mg dose of [14C]-saxagliptin, 24%, 36%, and 75% of the dose was excreted in the urine as saxagliptin, its active metabolite, and total radioactivity, respectively. The average renal clearance of saxagliptin (~230 mL/min) was greater than the average estimated glomerular filtration rate (~120 mL/min), suggesting some active renal excretion. A total of 22% of the administered radioactivity was recovered in feces representing the fraction of the saxagliptin dose excreted in bile and/or unabsorbed drug from the gastrointestinal tract. Following a single oral dose of saxagliptin 5 mg to healthy subjects, the mean plasma terminal half-life (t½) for saxagliptin and its active metabolite was 2.5 and 3.1 hours, respectively.
Specific Populations
Effects Of Age, Gender, Race And Body Weight On Pharmacokinetics
Based on a population pharmacokinetic analysis, age, gender, race, and body weight do not have a clinically meaningful effect on the pharmacokinetics of saxagliptin and dapagliflozin.
Renal Impairment
Dapagliflozin
At steady state (20 mg once daily dapagliflozin for 7 days), patients with type 2 diabetes mellitus with mild, moderate, or severe renal impairment (as determined by eGFR) had geometric mean systemic exposures of dapagliflozin that were 45%, 100%, and 200% higher, respectively, as compared to patients with type 2 diabetes mellitus with normal renal function. Higher systemic exposure of dapagliflozin in patients with type 2 diabetes mellitus with renal impairment did not result in a correspondingly higher 24-hour urinary glucose excretion. The steady-state 24-hour urinary glucose excretion in patients with type 2 diabetes mellitus and mild, moderate, and severe renal impairment was 42%, 80%, and 90% lower, respectively, than in patients with type 2 diabetes mellitus with normal renal function. The impact of hemodialysis on dapagliflozin exposure is not known [see DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS and Use In Specific Populations].
Saxagliptin
A single-dose, open-label study was conducted to evaluate the pharmacokinetics of saxagliptin (10 mg dose) in subjects with varying degrees of chronic renal impairment compared to subjects with normal renal function. The 10 mg dosage is not an approved dosage. The degree of renal impairment did not affect Cmax of saxagliptin or its metabolite. In subjects with moderate renal impairment (eGFR 30 to less than 45 mL/min/1.73 m²), severe renal impairment (eGFR 15 to less than 30 mL/min/1.73 m²) and ESRD patient on hemodialysis, the AUC values of saxagliptin or its active metabolite were >2-fold higher than AUC values in subjects with normal renal function. QTERN is contraindicated in patients with an eGFR <45 mL/min/1.73 m².
Hepatic Impairment
Dapagliflozin
In subjects with mild and moderate hepatic impairment (Child-Pugh classes A and B), mean Cmax and AUC of dapagliflozin were up to 12% and 36% higher, respectively, as compared to healthy matched control subjects following single-dose administration of 10 mg dapagliflozin. These differences were not considered to be clinically meaningful. In patients with severe hepatic impairment (Child-Pugh class C), mean Cmax and AUC of dapagliflozin were up to 40% and 67% higher, respectively, as compared to healthy matched controls [see Use In Specific Populations].
Saxagliptin
In subjects with hepatic impairment (Child-Pugh classes A, B, and C), mean Cmax and AUC of saxagliptin were up to 8% and 77% higher, respectively, compared to healthy matched controls following administration of a single 10 mg dose of saxagliptin. The 10 mg dosage is not an approved dosage. The corresponding Cmax and AUC of the active metabolite were up to 59% and 33% lower, respectively, compared to healthy matched controls. These differences are not considered to be clinically meaningful.
Pediatric
Pharmacokinetics of QTERN in the pediatric population has not been studied.
Drug Interactions
Saxagliptin And Dapagliflozin
The lack of pharmacokinetic interaction between dapagliflozin and saxagliptin was demonstrated in a drug-drug interaction study between dapagliflozin and saxagliptin.
Dapagliflozin
In Vitro Assessment Of Drug Interactions
The metabolism of dapagliflozin is primarily via glucuronide conjugation mediated by UDP glucuronosyltransferase 1A9 (UGT1A9).
In in vitro studies, dapagliflozin and dapagliflozin 3-O-glucuronide neither inhibited CYP 1A2, 2C9, 2C19, 2D6, or 3A4, nor induced CYP 1A2, 2B6, or 3A4. Dapagliflozin is a weak substrate of the P-glycoprotein (P-gp) active transporter, and dapagliflozin 3-O-glucuronide is a substrate for the OAT3 active transporter. Dapagliflozin or dapagliflozin 3-O-glucuronide did not meaningfully inhibit P-gp, OCT2, OAT1, or OAT3 active transporters. Overall, dapagliflozin is unlikely to affect the pharmacokinetics of concurrently administered medications that are P-gp, OCT2, OAT1, or OAT3 substrates.
Effects Of Other Drugs On Dapagliflozin
Table 4 shows the effect of coadministered drugs on the pharmacokinetics of dapagliflozin.
Table 4: Effects of Coadministered Drugs on Dapagliflozin Systemic Exposure
| Coadministered Drug (Dose Regimen)* |
Dapagliflozin (Dose Regimen)* |
Dapagliflozin |
| Change† in AUC‡ |
Change† , in Cmax |
| Oral Antidiabetic Agents |
| Metformin (1000 mg) |
20 mg |
↓1% |
↓7% |
| Pioglitazone (45 mg) |
50 mg |
0% |
↑9% |
| Sitagliptin (100 mg) |
20 mg |
↑8% |
↓4% |
| Glimepiride (4 mg) |
20 mg |
↓1% |
↓1% |
| Voglibose (0.2 mg three times daily) |
10 mg |
↑1% |
↑4% |
| Saxagliptin (5 mg single dose) |
10 mg (single dose) |
↓2% |
↓6% |
| Other Medications |
| Hydrochlorothiazide (25 mg) |
50 mg |
↑7% |
↓1% |
| Bumetanide (1 mg) |
10 mg once daily for 7 days |
↑5% |
↑8% |
| Valsartan (320 mg) |
20 mg |
↑2% |
↓12% |
| Simvastatin (40 mg) |
20 mg |
↓1% |
↓2% |
| Anti-infective Agent |
| Rifampin (600 mg once daily for 6 days) |
10 mg |
↓22% |
↓7% |
| Nonsteroidal Anti-inflammatory Agent |
| Mefenamic Acid (loading dose of 500 mg followed by 14 doses of 250 mg every 6 hours) |
10 mg |
↑51% |
↓13% |
*Single dose unless otherwise noted.
† Percent change (with/without coadministered drug and no change=0%); ↑ and ↓ indicate the exposure increase and decrease, respectively.
‡AUC=AUC(INF) for drugs given as single dose and AUC=AUC(TAU) for drugs given in multiple doses. |
Effects Of Dapagliflozin On Other Drugs
Table 5 shows the effect of dapagliflozin on other coadministered drugs. Dapagliflozin did not meaningfully affect the pharmacokinetics of the coadministered drugs.
Table 5: Effects of Dapagliflozin on the Systemic Exposures of Coadministered Drugs
| Coadministered Drug (Dose Regimen)* |
Dapagliflozin (Dose Regimen)* |
Coadministered Drug |
| Change† in AUC‡ |
Change† in Cmax |
| Oral Antidiabetic Agents |
| Metformin (1000 mg) |
20 mg |
0% |
↓5% |
| Pioglitazone (45 mg) |
50 mg |
0% |
↓7% |
| Sitagliptin (100 mg) |
20 mg |
↑1% |
↓11% |
| Glimepiride (4 mg) |
20 mg |
↑13% |
↑4% |
| Other Medications |
| Hydrochlorothiazide (25 mg) |
50 mg |
↓1% |
↓5% |
| Bumetanide (1 mg) |
10 mg once daily for 7 days |
↑13% |
↑13% |
| Valsartan (320 mg) |
20 mg |
↑5% |
↓6% |
| Simvastatin (40 mg) |
20 mg |
↑19% |
↓6% |
| Digoxin (0.25 mg) |
20 mg loading dose then 10 mg once daily for 7 days |
0% |
↓1% |
| Warfarin (25 mg) S-warfarin R-warfarin |
20 mg loading dose then 10 mg once daily for 7 days |
↑3% |
↑7% |
| ↑6% |
↑8% |
* Single dose unless otherwise noted.
† Percent change (with/without coadministered drug and no change=0%); ↑ and ↓ indicate the exposure increase and decrease, respectively.
‡ AUC=AUC(INF) for drugs given as single dose and AUC=AUC(TAU) for drugs given in multiple doses. |
Saxagliptin
In Vitro Assessment Of Drug Interactions
The metabolism of saxagliptin is primarily mediated by CYP3A4/5.
In in vitro studies, saxagliptin and its active metabolite did not inhibit CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, or 3A4, or induce CYP1A2, 2B6, 2C9, or 3A4. Therefore, saxagliptin is not expected to alter the metabolic clearance of coadministered drugs that are metabolized by these enzymes. Saxagliptin is a P-glycoprotein (P-gp) substrate but is not a significant inhibitor or inducer of P-gp.
Effects Of Other Drugs On Saxagliptin And Its Active Metabolite, 5-hydroxy Saxagliptin
Table 6: Effect of Coadministered Drugs on Systemic Exposures of Saxagliptin and its Active Metabolite, 5-hydroxy Saxagliptin
| Co- administered Drug |
Dosage of Coadministered Drug* |
Dosage of Saxagliptin* |
Saxagliptin |
|
Change† in AUC‡ |
Change† in Cmax |
| Metformin |
1000 mg |
100 mg |
saxagliptin |
↓2% |
↓21% |
| 5-hydroxy saxagliptin |
↓1% |
↓12% |
| Glyburide |
5 mg |
10 mg |
saxagliptin |
↓2% |
↑8% |
| 5-hydroxy saxagliptin |
ND |
ND |
| Pioglitazone§ |
45 mg QD for 10days |
10 mg QD |
saxagliptin |
↑11% |
↑11% |
| for 5 days |
5-hydroxy saxagliptin |
ND |
ND |
| Dapagliflozin |
10 mg single dose |
5 mg single |
saxagliptin |
↓1% |
↓7% |
| dose |
5-hydroxy saxagliptin |
↑9% |
↑6% |
| Digoxin |
0.25 mg q6h first day followed by q12h second day followed by QD for 5 days |
10 mg QD |
saxagliptin |
↑5% |
↓1% |
| for 7 days |
5-hydroxy saxagliptin |
↑6% |
↑2% |
| Simvastatin |
40 mg QD for 8days |
10 mg QD |
saxagliptin |
↑12% |
↑21% |
| for 4 days |
5-hydroxy saxagliptin |
↑2% |
↑8% |
| Diltiazem |
360 mg LA QD for 9 days |
10 mg |
saxagliptin |
↑109% |
↑63% |
|
5-hydroxy saxagliptin |
↓34% |
↓43% |
| Rifampin¶ |
600 mg QD for 6days |
5 mg |
saxagliptin |
↓76% |
↓53% |
|
5-hydroxy saxagliptin |
↑3% |
↓39% |
| Omeprazole |
40 mg QD for 5days |
10 mg |
saxagliptin |
↑13% |
↓2% |
|
5-hydroxy saxagliptin |
ND |
ND |
| Aluminum hydroxide + magnesium hydroxide + simethicone |
aluminum hydroxide: 2400 mg magnesium hydroxide: 2400 mg simethicone: 240 mg |
10 mg |
saxagliptin |
↓3% |
↓26% |
|
5-hydroxy saxagliptin |
ND |
ND |
| Famotidine |
40 mg |
10 mg |
saxagliptin |
↑3% |
↑14% |
| 5-hydroxy saxagliptin |
ND |
ND |
| Saxagliptin coadministered with strong CYP3A4/5 inhibitors [see DRUG INTERACTIONS and DOSAGE AND ADMINISTRATION]: |
| Ketoconazole |
200 mg BID for 9days |
100 mg |
saxagliptin |
↑145% |
↑62 % |
| 5-hydroxy saxagliptin |
↓88% |
↓95% |
| Ketoconazole |
200 mg BID for 7days |
20 mg |
saxagliptin |
↑267% |
↑144% |
| 5-hydroxy saxagliptin |
ND |
ND |
ND=not determined; QD=once daily; q6h=every 6 hours; q12h=every 12 hours; BID=twice daily; LA=long acting.
* Single dose unless otherwise noted.
† Percent change (with/without coadministered drug and no change=0%); ↑ and ↓ indicate the exposure increase and decrease, respectively.
‡ AUC=AUC(INF) for drugs given as single dose and AUC=AUC(TAU) for drugs given in multiple doses.
§ Results exclude one subject.
¶ The plasma dipeptidyl peptidase-4 (DPP-4) activity inhibition over a 24-hour dose interval was not affected by rifampin. |
Effects Of Saxagliptin On Other Drugs
Table 7: Effect of Saxagliptin on Systemic Exposures of Coadministered Drugs
| Coadministered Drug |
Dosage of Coadministered Drug* |
Dosage of Saxagliptin* |
Coadministered Drug |
|
Change† in AUC‡ |
Change† in Cmax |
| Metformin |
1000 mg |
100 mg |
metformin |
↑20% |
↑9% |
| Glyburide |
5 mg |
10 mg |
glyburide |
↑6% |
↑16% |
| Pioglitazone§ |
45 mg QD for 10days |
10 mg QD |
pioglitazone |
↑8% |
↑14% |
| for 5 days |
hydroxy-pioglitaz one |
ND |
ND |
| Digoxin |
0.25 mg q6h first day followed by q12h second day followed by QD for 5 days |
10 mg QD for 7 days |
digoxin |
↑6% |
↑9% |
| Simvastatin |
40 mg QD for 8days |
10 mg QD |
simvastatin |
↑4% |
↓12% |
| for 4 days |
simvastatin acid |
↑16% |
0% |
| Diltiazem |
360 mg LA QD for 9 days |
10 mg |
diltiazem |
↑10% |
↑16% |
| Ketoconazole |
200 mg BID for 9 days |
100 mg |
ketoconazole |
↓13% |
↓16% |
| Ethinyl estradiol and Norgestimate |
ethinyl estradiol 0.035 mg and norgestimate 0.250 mg for 21 days |
5 mg QD for 21 days |
ethinyl estradiol |
↑7% |
↓2% |
| norelgestromin |
↑10% |
↑9% |
| norgestrel |
↑13% |
↑17% |
ND=not determined; QD=once daily; q6h=every 6 hours; q12h=every 12 hours; BID=twice daily; LA=long acting.
* Single dose unless otherwise noted.
† Percent change (with/without coadministered drug and no change=0%); ↑ and ↓ indicate the exposure increase and decrease, respectively.
‡ AUC=AUC(INF) for drugs given as single dose and AUC=AUC(TAU) for drugs given in multiple doses.
§ Results include all subjects. |
Animal Toxicology And/Or Pharmacology
Saxagliptin
Saxagliptin produced adverse skin changes in the extremities of cynomolgus monkeys (scabs and/or ulceration of tail, digits, scrotum, and/or nose). Skin lesions were reversible within exposure approximately 20-times the 5 mg clinical dose, but in some cases were irreversible and necrotizing at higher exposures. Adverse skin changes were not observed at exposures similar to (1-to 3-times) the 5 mg clinical dose. Clinical correlates to skin lesions in monkeys have not been observed in human clinical trials of saxagliptin.
Clinical Studies
The dapagliflozin and saxagliptin in combination with metformin has been studied in adult patients with type 2 diabetes mellitus (T2DM) inadequately controlled on metformin in the following studies.
Treatment with dapagliflozin and saxagliptin and metformin (combination or add-on therapy) at all doses produced statistically significant improvements in HbA1c compared to the active comparator or placebo study arms in combination with metformin.
Add-On Therapy With Dapagliflozin Plus Saxagliptin In Patients On Metformin
Adult patients with inadequately controlled type 2 diabetes mellitus participated in 2 active-controlled studies of 24-week duration to evaluate therapy with 5 mg dapagliflozin/5 mg saxagliptin or 10 mg dapagliflozin/5 mg saxagliptin combinations on a background of metformin.
One study was a 24-week randomized, double-blind, active-controlled, parallel-group study (NCT02681094) in T2DM patients with an HbA1c ≥7.5% and ≤10.0%. Patients were on a stable dose of metformin HCl (≥1500 mg per day) for at least 8 weeks prior to being randomized to one of three double-blind treatment groups to receive 5 mg dapagliflozin and 5 mg saxagliptin added to metformin, 5 mg saxagliptin and placebo added to metformin, or 5 mg dapagliflozin and placebo added to metformin.
At Week 24, concomitant addition of 5 mg dapagliflozin and 5 mg saxagliptin plus metformin resulted in statistically significant decreases in HbA1c, and a larger proportion of patients achieving the therapeutic glycemic goal of HbA1c <7%, compared to dapagliflozin plus metformin or saxagliptin plus metformin (see Table 8).
Table 8: HbA1c Results at Week 24 with the Combination of 5 mg Dapagliflozin and 5 mg Saxagliptin plus Metformin*
| Efficacy Parameter |
5 mg Dapagliflozin and 5 mg Saxagliptin + Metformin |
| 5 mg Dapagliflozin and 5 mg Saxagliptin + Metformin |
5 mg Dapagliflozin + Metformin |
5 mg Saxagliptin + Metformin |
| N† |
290 |
289 |
291 |
| Baseline (mean) |
8.1 |
8.2 |
8.3 |
| Change from baseline (adjusted mean) (95% CI) |
-1.02
(-1.13, -0.90) |
-0.62
(-0.73, -0.51) |
-0.69
(-0.80, -0.59) |
| Difference from dapagliflozin + metformin (adjusted mean) (95% CI) |
-0.40‡
(-0.55, -0.24) |
|
|
| Difference from saxagliptin + metformin (adjusted mean) (95% CI) |
-0.32‡
(-0.48, -0.17) |
|
|
| Percent of patients achieving HbA1c <7% |
42.8 |
21.8§ |
28.5¶ |
* Analysis of Covariance including all post-baseline data regardless of rescue or treatment discontinuation. Model estimates calculated using multiple imputation to model washout of the treatment effect using control arm data for all subjects having missing Week 24 data.
† The number of randomized subjects who took at least one dose of double-blind study medication and had a baseline value for HbA1c.
‡ p-value <0.0001.
§ p-value <0.0001 vs. dapagliflozin and saxagliptin plus metformin.
¶ p-value = 0.0018 vs. dapagliflozin and saxagliptin plus metformin. |
The adjusted mean change from baseline for body weight at Week 24, using values regardless of rescue or treatment discontinuation, was -2.0 kg for the 5 mg dapagliflozin and 5 mg saxagliptin plus metformin group, -2.1 kg for the 5 mg dapagliflozin plus metformin group, and -0.4 kg for the 5 mg saxagliptin plus metformin group. The difference in mean body weight between the 5 mg dapagliflozin and 5 mg saxagliptin plus metformin group and the 5 mg dapagliflozin plus metformin group was -1.6 kg (95% CI [-2.1, -1.0]).
The second study was a 24-week randomized, double-blind, active comparator-controlled superiority study (NCT016060007) that compared once daily 10 mg dapagliflozin and 5 mg saxagliptin coadministered in combination with metformin XR with either 10 mg dapagliflozin and placebo added to metformin or 5 mg saxagliptin and placebo added to metformin in T2DM adult patients with inadequate glycemic control on metformin alone (HbA1c ≥8% and ≤12%).
At Week 24, concomitant addition of 10 mg dapagliflozin and 5 mg saxagliptin plus metformin resulted in statistically significant decreases in HbA1c, and a larger proportion of patients achieving an HbA1c <7%, compared to dapagliflozin plus metformin or saxagliptin plus metformin (see Table 9).
Table 9: HbA1c Results at Week 24 with the Combination of 10 mg Dapagliflozin and 5 mg Saxagliptin plus Metformin*
| Efficacy Parameter |
10 mg Dapagliflozin and 5 mg Saxagliptin + Metformin |
| 10 mg Dapagliflozin and 5 mg Saxagliptin + Metformin |
10 mg Dapagliflozin + Metformin |
5 mg Saxagliptin + Metformin |
| N† |
179 |
179 |
176 |
| Baseline (mean) |
8.9 |
8.9 |
9.0 |
| Change from baseline (adjusted mean) (95% CI) |
-1.49
(-1.64, -1.34) |
-1.23
(-1.38, -1.08) |
-1.00
(-1.15, -0.85) |
| Difference from dapagliflozin + metformin (adjusted mean) (95% CI) |
−0.26‡
(−0.47, −0.05) |
|
|
| Difference from saxagliptin + metformin (adjusted mean) (95% CI) |
-0.49§
(-0.70, -0.27) |
|
|
| Percent of patients achieving HbA1c <7% |
40.2¶ |
21.2¶ |
16.5¶ |
* Analysis of Covariance including all post-baseline data regardless of rescue or treatment discontinuation. Model estimates calculated using multiple imputation to model washout of the treatment effect using control arm data for all subjects having missing Week 24 data.
† The number of randomized subjects who took at least one dose of double-blind study medication and had a baseline value for HbA1c.
‡ p-value=0.0148.
§ p-value <0.0001.
¶ Not statistically significant based on the prespecified method for controlling type I error. |
The adjusted mean change from baseline for body weight at Week 24, using values regardless of rescue or treatment discontinuation, was -2.0 kg for the 10 mg dapagliflozin and 5 mg saxagliptin plus metformin group, -2.3 kg for the 10 mg dapagliflozin plus metformin group, and 0 kg for the 5 mg saxagliptin plus metformin group.
Add-On Therapy With Saxagliptin In Patients On Dapagliflozin Plus Metformin
A total of 315 patients with type 2 diabetes mellitus participated in this 24-week randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of saxagliptin added to dapagliflozin and metformin in patients with a baseline of HbA1c ≥7% to ≤10.5% (NCT01619059). The mean age of these subjects was 54.6 years, 1.6% were 75 years or older and 52.7% were female. The population was 87.9% White, 6.3% Black or African American, 4.1% Asian, and 1.6% Other race. At baseline the population had diabetes for an average of 7.7 years and a mean HbA1c of 7.9%. The mean eGFR at baseline was 93.4 mL/min/1.73 m². Patients were required to be on a stable dose of metformin (≥1500 mg per day) for at least 8 weeks prior to enrollment. Eligible subjects who completed the screening period entered the lead-in treatment period, which included 16 weeks of open-label metformin and 10 mg dapagliflozin treatment. Following the lead-in period, eligible patients were randomized to 5 mg saxagliptin (N=153) or placebo (N=162).
The group treated with add-on saxagliptin had statistically significant greater reductions in HbA1c from baseline versus the group treated with placebo (see Table 10).
Table 10: HbA1c Change from Baseline at Week 24 in a Placebo-Controlled Trial of Saxagliptin as Add-on to Dapagliflozin and Metformin*
| Efficacy parameter |
5 mg Saxagliptin (N=153)† |
Placebo (N=162)† |
| In combination with Dapagliflozin and Metformin |
| HbA1c (%) at week 24‡ |
| Baseline (mean) |
8.0 |
7.9 |
| Change from baseline (adjusted mean§) 95% Confidence Interval |
-0.5 (-0.6, -0.4) |
-0.2 (-0.3, -0.1) |
| Difference from placebo (adjusted mean) 95% Confidence Interval |
−0.4¶ (-0.5, -0.2) |
| Percent of patients achieving HbA1c <7% |
35.3 |
23.1 |
* There were 6.5% (n=10) of randomized subjects in the saxagliptin arm and 3.1% (n=5) in the placebo arm for whom change from baseline HbA1c data was missing at Week 24. Of the subjects who discontinued study medication early, 9.1% (1 of 11) in the saxagliptin arm and 16.7% (1 of 6) in the placebo arm had HbA1c measured at Week 24.
† N is the number of randomized and treated patients.
‡ Analysis of Covariance including all post-baseline data regardless of rescue or treatment discontinuation. Model estimates calculated using multiple imputation to model washout of the treatment effect using placebo data for all subjects having missing Week 24 data.
§ Least squares mean adjusted for baseline value.
¶ p-value <0.0001. |
Cardiovascular Safety Trial
The cardiovascular risk of saxagliptin was evaluated in SAVOR (Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus -Thrombolysis in Myocardial Infarction), a multicenter, multinational, randomized, double-blind trial comparing saxagliptin (N=8280) to placebo (N=8212), in adult patients with type 2 diabetes mellitus at high risk for atherosclerotic cardiovascular disease. Of the randomized study subjects, 97.5% completed the trial, and the median duration of follow-up was approximately 2 years (NCT01107886).
Subjects were at least 40 years of age, had HbA1c ≥6.5%, and multiple risk factors (21% of randomized subjects) for cardiovascular disease (age ≥55 years for men and ≥60 years for women plus at least one additional risk factor of dyslipidemia, hypertension, or current cigarette smoking) or established (79% of the randomized subjects) cardiovascular disease defined as a history of ischemic heart disease, peripheral vascular disease, or ischemic stroke. Overall, the use of diabetes medications was balanced across treatment groups (metformin 69%, insulin 41%, sulfonylureas 40%, and TZDs 6%). The use of cardiovascular disease medications was also balanced (angiotensin-converting enzyme [ACE] inhibitors or angiotensin receptor blockers [ARBs] 79%, statins 78%, aspirin 75%, beta-blockers 62%, and non-aspirin antiplatelet medications 24%).
The majority of subjects were male (67%) and Caucasian (75%) with a mean age of 65 years. Approximately 16% of the population had moderate (eGFR ≥30 to ≤50 mL/min/1.73 m²) to severe (eGFR <30 mL/min/1.73 m²) renal impairment, and 13% had a prior history of heart failure. QTERN is contraindicated in patients with an eGFR <45 mL/min/1.73 m². Subjects had a median duration of type 2 diabetes mellitus of approximately 10 years and a mean baseline HbA1c level of 8.0%.
The primary analysis in SAVOR was time to first occurrence of a Major Adverse Cardiac Event (MACE). A major adverse cardiac event in SAVOR was defined as a cardiovascular death or a nonfatal myocardial infarction (MI) or a nonfatal ischemic stroke. The incidence rate of MACE was similar in both treatment arms: 3.8 MACE per 100 patient-years on placebo vs. 3.8 MACE per 100 patient-years on saxagliptin with an estimated HR: 1.0; 95.1% CI: (0.89, 1.12). The upper bound of this confidence interval, 1.12, excluded a risk margin larger than 1.3.
Vital status was obtained for 99% of subjects in the trial. There were 798 deaths in the SAVOR trial. Numerically more patients (5.1%) died in the saxagliptin group than in the placebo group (4.6%). The risk of deaths from all-cause mortality was not statistically different between the treatment groups (HR: 1.11; 95.1% CI: 0.96, 1.27).