Pharmacology: Mechanism of Action: 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 β cells in a glucose-dependent manner but are inactivated by the DPP4 enzyme within min. Glucagon-like-peptide-1 (GLP-1) also lowers glucagon secretion from pancreatic α cells, reducing hepatic glucose production. In patients with type 2 diabetes, concentrations of GLP-1 are reduced but the insulin response to GLP-1 is preserved. Saxagliptin is a competitive DPP4 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: In patients with type 2 diabetes mellitus, administration of Onglyza inhibits DPP4 enzyme activity for a 24-hr period. After an oral glucose load or a meal, this DPP4 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 β 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: In a randomized, double-blind, placebo-controlled, 4-way crossover, active comparator study using moxifloxacin in 40 healthy subjects, Onglyza was not associated with clinically meaningful prolongation of the QTc interval or heart rate at daily doses up to 40 mg [8 times the maximum recommended dose (MRHD)].
Clinical Safety and Efficacy: Onglyza has been studied as monotherapy and in combination with metformin, glyburide and thiazolidinedione (pioglitazone and rosiglitazone) therapy.
A total of 4148 patients with type 2 diabetes mellitus were randomized in 6, double-blind, controlled clinical trials conducted to evaluate the safety and glycemic efficacy of Onglyza. A total of 3021 patients in these trials were treated with Onglyza. In these trials, the mean age was 54 years, and 71% of patients were Caucasian, 16% were Asian, 4% were Black, and 9% were of other racial groups. An additional 423 patients, including 315 who received Onglyza, participated in a placebo-controlled, dose-ranging study of 6-12 weeks in duration.
In these 6, double-blind trials, Onglyza was evaluated at doses of 2.5 mg and 5 mg once daily. Three of these trials also evaluated a dose of saxagliptin 10 mg daily. The saxagliptin 10 mg daily dose did not provide greater efficacy than the 5 mg daily dose. Treatment with Onglyza at all doses produced clinically relevant and statistically significant improvements in hemoglobin A1c (A1C), fasting plasma glucose (FPG), and 2-hr postprandial glucose (PPG) following a standard oral glucose tolerance test (OGTT), compared to control. Reductions in A1C were seen across subgroups including gender, age, race and baseline BMI.
Onglyza was not associated with significant changes from baseline in body weight or fasting serum lipids compared to placebo.
Onglyza has also been evaluated in 3 additional trials in patients with type 2 diabetes: An active-controlled trial comparing add-on therapy with Onglyza to glipizide in 858 patients inadequately controlled on metformin alone, a trial comparing Onglyza to placebo in 455 patients inadequately controlled on insulin alone or on insulin in combination with metformin, and a trial comparing Onglyza to placebo in 170 patients with type 2 diabetes and moderate or severe renal impairment or ESRD.
Saxagliptin as Monotherapy: A total of 766 patients with type 2 diabetes inadequately controlled on diet and exercise (A1C ≥7% to ≤10%) participated in two 24-week, double-blind, placebo-controlled trials evaluating the efficacy and safety of Onglyza monotherapy.
In the 1st trial, following a 2-week single-blind diet, exercise, and placebo lead-in period, 401 patients were randomized to Onglyza 2.5 mg, 5 mg, or 10 mg or placebo. Patients who failed to meet specific glycemic goals during the study were treated with metformin rescue therapy, added on to placebo or Onglyza. Efficacy was evaluated at the last measurement prior to rescue therapy for patients needing rescue. Dose titration of Onglyza was not permitted.
Treatment with Onglyza 2.5 mg and 5 mg daily provided significant improvements in A1C, FPG, and PPG compared to placebo (Table 1). The percentage of patients who discontinued for lack of glycemic control or who were rescued for meeting prespecified glycemic criteria was 16% in the Onglyza 2.5 mg treatment group, 20% in the Onglyza5 mg treatment group, and 26% in the placebo group. See Table 1.
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A second 24-week monotherapy trial was conducted to assess a range of dosing regimens for Onglyza. Treatment-naive patients with inadequately controlled diabetes (A1C ≥7% to ≤10%) underwent a 2-week, single-blind diet, exercise, and placebo lead-in period. A total of 365 patients were randomized to Onglyza 2.5 mg every morning, 5 mg every morning, 2.5 mg with possible titration to 5 mg every morning, or 5 mg every evening, or placebo. Patients who failed to meet specific glycemic goals during the study were treated with metformin rescue therapy added on to placebo or Onglyza; the number of patients randomized per treatment group ranged from 71-74.
Treatment with either Onglyza 5 mg every morning or 5 mg every evening provided significant improvements in A1C versus placebo (mean placebo-corrected reductions of -0.4% and -0.3%, respectively). Treatment with Onglyza 2.5 mg every morning also provided significant improvement in A1C versus placebo (mean placebo-corrected reduction of -0.4%).
Combination Therapy: Saxagliptin Add-on to Metformin Therapy: A total of 743 patients with type 2 diabetes participated in this 24-week, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of Onglyza in combination with metformin in patients with inadequate glycemic control (A1C ≥7% and ≤10%) on metformin alone. To qualify for enrollment, patients were required to be on a stable dose of metformin (1500-2550 mg daily) for at least 8 weeks.
Patients who met eligibility criteria were enrolled in a single-blind, 2-week, dietary and exercise placebo lead-in period during which patients received metformin at their pre-study dose, up to 2500 mg daily. Following the lead-in period, eligible patients were randomized to Onglyza 2.5 mg, 5 mg, or 10 mg or placebo in addition to their current dose of open-label metformin. Patients who failed to meet specific glycemic goals during the study were treated with pioglitazone rescue therapy, added on to existing study medications. Dose titrations of Onglyza and metformin were not permitted.
Onglyza 2.5 mg and 5 mg add-on to metformin provided significant improvements in A1C, FPG, and PPG compared with placebo add-on to metformin (Table 2). Mean changes from baseline for A1C over time and at endpoint are shown in Figure 1. The proportion of patients who discontinued for lack of glycemic control or who were rescued for meeting prespecified glycemic criteria was 15% in the Onglyza 2.5 mg add-on to metformin group, 13% in the Onglyza 5 mg add-on to metformin group, and 27% in the placebo add-on to metformin group. See Table 2 & figure.
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Add-on Combination Therapy with a Thiazolidinedione: A total of 565 patients with type 2 diabetes participated in this 24-week, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of Onglyza in combination with a thiazolidinedione (TZD) in patients with inadequate glycemic control (A1C ≥7% to ≤10.5%) on TZD alone. To qualify for enrollment, patients were required to be on a stable dose of pioglitazone (30-45 mg once daily) or rosiglitazone (4 mg once daily or 8 mg either once daily or in two divided doses of 4 mg) for at least 12 weeks.
Patients who met eligibility criteria were enrolled in a single-blind, 2-week, dietary and exercise placebo lead-in period during which patients received TZD at their pre-study dose. Following the lead-in period, eligible patients were randomized to 2.5 mg or 5 mg of Onglyza or placebo in addition to their current dose of TZD. Patients who failed to meet specific glycemic goals during the study were treated with metformin rescue, added on to existing study medications. Dose titration of Onglyza or TZD was not permitted during the study. A change in TZD regimen from rosiglitazone to pioglitazone at specified, equivalent therapeutic doses was permitted at the investigator’s discretion if believed to be medically appropriate.
Onglyza 2.5 mg and 5 mg add-on to TZD provided significant improvements in A1C, FPG, and PPG compared with placebo add-on to TZD (Table 3). The proportion of patients who discontinued for lack of glycemic control or who were rescued for meeting prespecified glycemic criteria was 10% in the Onglyza 2.5 mg add-on to TZD group, 6% for the Onglyza 5 mg add-on to TZD group, and 10% in the placebo add-on to TZD group. See Table 3.
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Add-on Combination Therapy with Glyburide: A total of 768 patients with type 2 diabetes participated in this 24-week, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of Onglyza in combination with a sulfonylurea (SU) in patients with inadequate glycemic control at enrollment (A1C ≥7.5% to ≤10%) on a submaximal dose of SU alone. To qualify for enrollment, patients were required to be on a submaximal dose of SU for 2 months or greater. In this study, Onglyza in combination with a fixed, intermediate dose of SU was compared to titration to a higher dose of SU.
Patients who met eligibility criteria were enrolled in a single-blind, 4-week, dietary and exercise lead-in period, and placed on glyburide 7.5 mg once daily. Following the lead-in period, eligible patients with A1C ≥7% to ≤10% were randomized to either Onglyza 2.5 mg or 5 mg add-on to glyburide 7.5 mg or to placebo plus a total daily dose of glyburide 10 mg. Patients who received placebo were eligible to have glyburide up-titrated to a total daily dose of 15 mg. Up titration of glyburide was not permitted in patients who received Onglyza 2.5 mg or 5 mg. Glyburide could be down-titrated in any treatment group once during the 24-week study period due to hypoglycemia as deemed necessary by the investigator. Approximately 92% of patients in the placebo plus glyburide group were up-titrated to a final total daily dose of 15 mg during the 1st 4 weeks of the study period. Patients who failed to meet specific glycemic goals during the study were treated with metformin rescue, added on to existing study medication. Dose titration of Onglyza was not permitted during the study.
In combination with glyburide, Onglyza 2.5 mg and 5 mg provided significant improvements in A1C, FPG, and PPG compared with the placebo plus up-titrated glyburide group (Table 4). The proportion of patients who discontinued for lack of glycemic control or who were rescued for meeting prespecified glycemic criteria was 18% in the Onglyza 2.5 mg add-on to glyburide group, 17% in the Onglyza 5 mg add-on to glyburide group, and 30% in the placebo plus up-titrated glyburide group. See Table 4.
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Add-on Combination Therapy with Metformin versus Glipizide Add-on Combination Therapy with Metformin: In this 52-week, active-controlled trial, a total of 858 patients with type 2 diabetes and inadequate glycemic control (A1C >6.5% and ≤10%) on metformin alone were randomized to double-blind add-on therapy with Onglyza or glipizide. Patients were required to be on a stable dose of metformin (at least 1500 mg daily) for at least 8 weeks prior to enrollment.
Patients who met eligibility criteria were enrolled in a single-blind, 2-week, dietary and exercise placebo lead-in period during which patients received metformin (1500-3000 mg based on their pre-study dose). Following the lead-in period, eligible patients were randomized to Onglyza 5 mg or glipizide 5 mg in addition to their current dose of open-label metformin. Patients in the glipizide plus metformin group underwent blinded titration of the glipizide dose during the 1st 18 weeks of the trial up to a maximum glipizide dose of 20 mg per day. Titration was based on a goal FPG ≤110 mg/dL or the highest tolerable glipizide dose. Fifty percent (50%) of the glipizide-treated patients were titrated to the 20-mg daily dose; 21% of the glipizide-treated patients had a final daily dose of glipizide 5 mg or less. The mean final daily dose of glipizide was 15 mg.
After 52 weeks of treatment, Onglyza and glipizide resulted in similar mean reductions from baseline in A1C when added to metformin therapy (Table 5). This conclusion may be limited to patients with baseline A1C comparable to those in the trial (91% of patients had baseline A1C <9%).From a baseline mean body weight of 89 kg, there was a statistically significant mean reduction of 1.1 kg in patients treated with Onglyza compared to a mean weight gain of 1.1 kg in patients treated with glipizide (p<0.0001). See Table 5.
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Add-on Combination Therapy with Insulin (with/without Metformin): A total of 455 patients with type 2 diabetes participated in this 24-week, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of Onglyza in combination with insulin in patients with inadequate glycemic control (A1C ≥7.5% and ≤11%) on insulin alone (N=141) or on insulin in combination with a stable dose of metformin (N=314). Patients were required to be on a stable dose of insulin (≥30 units to ≤150 units daily) with ≤20% variation in total daily dose for ≥8 weeks prior to screening. Patients entered the trial on intermediate- or long-acting (basal) insulin or premixed insulin. Patients using short-acting insulins were excluded unless the short-acting insulin was administered as part of a premixed insulin.
Patients who met eligibility criteria were enrolled in a single-blind, 4-week, dietary and exercise placebo lead-in period during which patients received insulin (and metformin if applicable) at their pretrial dose(s). Following the lead-in period, eligible patients were randomized to add-on therapy with either Onglyza 5 mg or placebo. Doses of the antidiabetic therapies were to remain stable but patients were rescued and allowed to adjust the insulin regimen if specific glycemic goals were not met or if the investigator learned that the patient had self-increased the insulin dose by >20%. Data after rescue were excluded from the primary efficacy analyses.
Add-on therapy with Onglyza 5 mg provided significant improvements from baseline to Week 24 in A1C and PPG compared with add-on placebo (Table 6). Similar mean reductions in A1C versus placebo were observed for patients using Onglyza 5 mg add-on to insulin alone and Onglyza 5 mg add-on to insulin in combination with metformin (−0.4% and −0.4%, respectively). The percentage of patients who discontinued for lack of glycemic control or who were rescued was 23% in the Onglyza group and 32% in the placebo group.
The mean daily insulin dose at baseline was 53 units in patients treated with Onglyza 5 mg and 55 units in patients treated with placebo.The mean change from baseline in daily dose of insulin was 2 units for the Onglyza 5 mg group and 5 units for the placebo group. See Table 6.
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Renal Impairment: A total of 170 patients participated in a 12-week, randomized, double-blind, placebo-controlled trial conducted to evaluate the efficacy and safety of Onglyza 2.5 mg once daily compared with placebo in patients with type 2 diabetes and moderate (n=90) or severe (n=41) renal impairment or ESRD (n=39). In this trial, 98% of the patients were using background antidiabetic medications (75% were using insulin and 31% were using oral antidiabetic medications, mostly sulfonylureas).
After 12 weeks of treatment, Onglyza 2.5 mg provided significant improvement in A1C compared to placebo (Table 7). In the subgroup of patients with ESRD, Onglyza and placebo resulted in comparable reductions in A1C from baseline to Week 12. This finding is inconclusive because the trial was not adequately powered to show efficacy within specific subgroups of renal impairment.
After 12 weeks of treatment, the mean change in FPG was −12 mg/dL with Onglyza 2.5 mg and −13 mg/dL with placebo. Compared to placebo, the mean change in FPG with Onglyza was −12 mg/dL in the subgroup of patients with moderate renal impairment, −4 mg/dL in the subgroup of patients with severe renal impairment, and +44 mg/dL in the subgroup of patients with ESRD. These findings are inconclusive because the trial was not adequately powered to show efficacy within specific subgroups of renal impairment. See Table 7.
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Pharmacokinetics: 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 peak concentration (C
max) and AUC values of saxagliptin and its active metabolite increased proportionally in the 2.5-400 mg dose range. Following a single oral dose of saxagliptin 5 mg 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 C
max values were 24 ng/mL and 47 ng/mL, respectively. The average variability (%CV) for AUC and C
max for both saxagliptin and its active metabolite was <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 2.5-400 mg.
Absorption: The median time to maximum concentration (T
max) following the 5 mg once daily dose was 2 hrs for saxagliptin and 4 hrs for its active metabolite. Administration with a high-fat meal resulted in an increase in T
max by approximately 20 min as compared to fasted conditions. There was a 27% increase in the AUC when given with a meal as compared to fasted conditions. Onglyza may be administered with or without food.
Distribution: The
in vitro protein-binding of saxagliptin and its major metabolite in human serum is negligible. Thus, changes in blood protein levels in various disease states (eg, renal or hepatic impairment) are not expected to alter the disposition of saxagliptin.
Metabolism: The metabolism of saxagliptin is primarily mediated by cytochrome P450 3A4/5 (CYP3A4/5). The major metabolite of saxagliptin is also a DPP4 inhibitor, which is ½ as potent as saxagliptin. Therefore, strong CYP3A4/5 inhibitors and inducers will alter the pharmacokinetics of saxagliptin and its active metabolite (see Interactions).
Excretion: 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 (approximately 230 mL/min) was greater than the average estimated glomerular filtration rate (approximately 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 Onglyza 5 mg to healthy subjects, the mean plasma terminal half-life for saxagliptin and its active metabolite was 2.5 hrs and 3.1 hrs, respectively.
Special Populations: Renal Impairment: A single-dose, open-label study was conducted to evaluate the pharmacokinetics of saxagliptin 10 mg in subjects with varying degrees of chronic renal impairment (N=8 per group) compared to subjects with normal renal function. The study included patients with renal impairment classified on the basis of creatinine clearance (CrCl) as mild (>50 to ≤80 mL/min), moderate (30 to ≤50 mL/min), and severe (<30 mL/min), as well as patients with end-stage renal disease on hemodialysis. Creatinine clearance was estimated from serum creatinine based on the Cockcroft-Gault formula:
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The degree of renal impairment did not affect the C
max of saxagliptin or its active metabolite. In subjects with mild renal impairment, the AUC values of saxagliptin and its active metabolite were 20% and 70% higher, respectively, than AUC values in subjects with normal renal function. Because increases of this magnitude are not considered to be clinically relevant, dosage adjustment in patients with mild renal impairment is not recommended. In subjects with moderate or severe renal impairment, the AUC values of saxagliptin and its active metabolite were up to 2.1- and 4.5-fold higher, respectively, than AUC values in subjects with normal renal function. To achieve plasma exposures of saxagliptin and its active metabolite similar to those in patients with normal renal function, the recommended dose is 2.5 mg once daily in patients with moderate and severe renal impairment, as well as in patients with end-stage renal disease requiring hemodialysis. Saxagliptin is removed by hemodialysis.
Hepatic Impairment: In subjects with hepatic impairment (Child-Pugh classes A, B and C), mean C
max and AUC of saxagliptin were up to 8% and 77% higher, respectively, compared to healthy matched controls following administration of a single dose of saxagliptin 10 mg. The corresponding C
max 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. No dosage adjustment is recommended for patients with hepatic impairment.
Body Mass Index: No dosage adjustment is recommended based on body mass index (BMI) which was not identified as a significant covariate on the apparent clearance of saxagliptin or its active metabolite in the population pharmacokinetic analysis.
Gender: No dosage adjustment is recommended based on gender. There were no differences observed in the pharmacokinetics between males and females. Compared to males, females had approximately 25% higher exposure values for the active metabolite than males, but this difference is unlikely to be of clinical relevance. Gender was not identified as a significant covariate on the apparent clearance of saxagliptin and its active metabolite in the population pharmacokinetic analysis.
Geriatric: No dosage adjustment is recommended based on age alone. Elderly subjects (65-80 years) had 23% and 59% higher geometric mean C
max and geometric mean AUC values, respectively, for saxagliptin than young subjects (18-40 years). Differences in active metabolite pharmacokinetics between elderly and young subjects generally reflected the differences observed in saxagliptin pharmacokinetics. The difference between the pharmacokinetics of saxagliptin and the active metabolite in young and elderly subjects is likely due to multiple factors including declining renal function and metabolic capacity with increasing age. Age was not identified as a significant covariate on the apparent clearance of saxagliptin and its active metabolite in the population pharmacokinetic analysis.
Pediatric: Studies characterizing the pharmacokinetics of saxagliptin in pediatric patients have not been performed.
Race and Ethnicity: No dosage adjustment is recommended based on race. The population pharmacokinetic analysis compared the pharmacokinetics of saxagliptin and its active metabolite in 309 Caucasian subjects with 105 non-Caucasian subjects (consisting of 6 racial groups). No significant difference in the pharmacokinetics of saxagliptin and its active metabolite were detected between these 2 populations.
Drug-Drug Interactions: 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 co-administered 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. See Table 8 and Table 9.
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Toxicology: Preclinical Safety Data: Saxagliptin did not induce tumors in either mice (50, 250 and 600 mg/kg) or rats (25, 75, 150 and 300 mg/kg) at the highest doses evaluated. The highest doses evaluated in mice were equivalent to approximately 870 (males) and 1165 (females) times the human exposure at the MRHD of 5 mg per day. In rats, exposures were approximately 355 (males) and 2217 (females) times the MRHD.
Saxagliptin was not mutagenic or clastogenic with or without metabolic activation in an
in vitro Ames bacterial assay, an
in vitro cytogenetics assay in primary human lymphocytes, an
in vivo oral micronucleus assay in rats, an
in vivo oral DNA repair study in rats, and an oral
in vivo/
in vitro cytogenetics study in rat peripheral blood lymphocytes. The active metabolite was not mutagenic in an
in vitro Ames bacterial assay.
In a rat fertility study, males were treated with oral gavage doses for 2 weeks prior to mating, during mating, and up to scheduled termination (approximately 4 weeks total) and females were treated with oral gavage doses for 2 weeks prior to mating through gestation day 7. No adverse effects on fertility were observed at exposures of approximately 603 (males) and 776 (females) times the MRHD. Higher doses that elicited maternal toxicity also increased fetal resorptions (approximately 2069 and 6138 times the MRHD). Additional effects on estrous cycling, fertility, ovulation and implantation were observed at approximately 6138 times the MRHD.
Animal Toxicology: 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 at ≥20 times the MRHD but in some cases were irreversible and necrotizing at higher exposures. Adverse skin changes were not observed at exposures similar to (1-3 times) the MRHD of 5 mg. Clinical correlates to skin lesions in monkeys have not been observed in human clinical trials of saxagliptin.