| Pharmacotherapeutic group: Drugs used in diabetes. Dipeptidyl peptidase 4 (DPP-4) inhibitors, ATC code: A10BH03 Mechanism of action and pharmacodynamic effects Saxagliptin is a highly potent (Ki: 1.3 nM), selective, reversible, competitive, DPP-4 inhibitor. In patients with type 2 diabetes, administration of saxagliptin led to inhibition of DPP-4 enzyme activity for a 24-hour period. After an oral glucose load, this DPP-4 inhibition resulted in a 2-to 3-fold increase in circulating levels of active incretin hormones, including glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), decreased glucagon concentrations and increased glucose-dependent beta-cell responsiveness, which resulted in higher insulin and C-peptide concentrations. The rise in insulin from pancreatic beta-cells and the decrease in glucagon from pancreatic alpha-cells were associated with lower fasting glucose concentrations and reduced glucose excursion following an oral glucose load or a meal. Saxagliptin improves glycaemic control by reducing fasting and postprandial glucose concentrations in patients with type 2 diabetes.Clinical safety and efficacy A total of 4,148 patients with type 2 diabetes, including 3,021 patients treated with, saxagliptin were randomised in 6 double-blind, controlled clinical safety and efficacy studies conducted to evaluate the effects of saxagliptin on glycaemic control. In these studies 634 patients were 65 years and older, while 59 patients were 75 years and older. Treatment with saxagliptin 5 mg once daily produced clinically relevant and statistically significant improvements in haemoglobin A1c (HbA1c), fasting plasma glucose (FPG) and postprandial glucose (PPG) compared to placebo in monotherapy, in combination with metformin (initial or add-on therapy), in combination with a sulphonylurea, and in combination with a thiazolidinedione (see Table 3). There was also no apparent change in body weight associated with saxagliptin. Reductions in HbA1c were seen across subgroups including gender, age, race, and baseline body mass index (BMI) and higher baseline HbA1c was associated with a greater adjusted mean change from baseline with saxagliptin. Saxagliptin as monotherapy Two double-blind, placebo-controlled studies of 24-week duration were conducted to evaluate the efficacy and safety of saxagliptin monotherapy in patients with type 2 diabetes. In both studies, once-daily treatment with saxagliptin provided significant improvements in HbA1c.Saxagliptin add-on to metformin therapy An add-on to metformin placebo-controlled study of 24-week duration was conducted to evaluate the efficacy and safety of saxagliptin in combination with metformin in patients with inadequate glycaemic control (HbA1c 7-10%) on metformin alone. Saxagliptin (n=186) provided significant improvements in HbA1c, FPG and PPG compared to placebo (n=175). Improvements in HbA1c, PPG, and FPG following treatment with saxagliptin 5 mg plus metformin were sustained up to Week 102. The HbA1c change for saxagliptin 5 mg plus metformin (n=31) compared to placebo plus metformin (n=15) was -0.8% at Week 102.Saxagliptin add-on to metformin compared with SU add-on to metformin A 52-week study was conducted to evaluate the efficacy and safety of saxagliptin 5 mg in combination with metformin (428 patients) compared with sulphonylurea (glipizide, 5 mg titrated as needed to 20 mg, mean dose of 15 mg) in combination with metformin (430 patients) in 858 patients with inadequate glycaemic control (HbA1c 6.5%-10%) on metformin alone. The mean metformin dose was approximately 1900 mg in each treatment group. After 52 weeks, the saxagliptin and glipizide groups had similar mean reductions from baseline in HbA1c in the per-protocol analysis (-0.7% vs. 0.8%, respectively, mean baseline HbA1c of 7.5% for both groups). The intent-to-treat analysis showed consistent results. The reduction in FPG was slightly less in the saxagliptin-group and there were more discontinuations (3.5% vs. 1.2%) due to lack of efficacy based on FPG criteria during the first 24 weeks of the study. Saxagliptin also resulted in a significantly lower proportion of patients with hypoglycaemia, 3% (19 events in 13 subjects) vs. 36.3% (750 events in 156 patients) for glipizide. Patients treated with saxagliptin exhibited a significant decrease from baseline in body weight compared to a weight gain in patients administered glipizide (-1.1 vs. +1.1 kg).Saxagliptin add-on to metformin compared with sitagliptin add-on to metformin An 18-week study was conducted to evaluate the efficacy and safety of saxagliptin 5 mg in combination with metformin (403 patients), compared with sitagliptin 100 mg in combination with metformin (398 patients) in 801 patients with inadequate glycaemic control on metformin alone. After 18 weeks, saxagliptin was non-inferior to sitagliptin in mean reduction from baseline in HbA1c in both the per-protocol and the full analysis sets . The reductions from baseline in HbA1c respectively for saxagliptin and sitagliptin in the primary per-protocol analysis were -0.5% (mean and median) and -0.6% (mean and median). In the confirmatory full analysis set, mean reductions were -0.4% and -0.6% respectively for saxagliptin and sitagliptin, with median reductions of -0.5% for both groups.Saxagliptin in combination with metformin as initial therapy A 24-week study was conducted to evaluate the efficacy and safety of saxagliptin 5 mg in combination with metformin as initial combination therapy in treatment-naïve patients with inadequate glycaemic control (HbA1c 8-12%). Initial therapy with the combination of saxagliptin 5 mg plus metformin (n=306) provided significant improvements in HbA1c, FPG and PPG compared to with either saxagliptin (n=317) or metformin (n=313) alone as initial therapy. Reductions in HbA1c from baseline to Week 24 were observed in all evaluated subgroups defined by baseline HbA1c, with greater reductions observed in patients with a baseline HbA1c 10% (see Table 3). Improvements in HbA1c, PPG and FPG following initial therapy with saxagliptin 5 mg plus metformin were sustained up to Week 76. The HbA1c change for saxagliptin 5 mg plus metformin (n=177) compared to metformin plus placebo (n=147) was -0.5% at Week 76.Saxagliptin add-on to glibenclamide therapy An add-on placebo-controlled study of 24-week duration was conducted to evaluate the efficacy and safety of saxagliptin in combination with glibenclamide in patients with inadequate glycaemic control at enrolment (HbA1c 7.5-10%) on a sub-maximal dose of glibenclamide alone. Saxagliptin in combination with a fixed, intermediate dose of a sulphonylurea (glibenclamide 7.5 mg) was compared to titration to a higher dose of glibenclamide (approximately 92% of patients in the placebo plus glibenclamide group were up-titrated to a final total daily dose of 15 mg). Saxagliptin (n=250) provided significant improvements in HbA1c, FPG and PPG compared to titration to a higher dose of glibenclamide (n=264). Improvements in HbA1c and PPG following treatment with saxagliptin 5 mg were sustained up to Week 76. The HbA1c change for saxagliptin 5 mg (n=56) compared to uptitrated glibenclamide plus placebo (n=27) was -0.7% at Week 76.Saxagliptin add-on combination therapy with insulin (with or without metformin) A total of 455 patients with type 2 diabetes participated in a 24-week randomised, double-blind, placebo-controlled study to evaluate the efficacy and safety of saxagliptin in combination with a stable dose of insulin (baseline mean: 54.2 Units) in patients with inadequate glycaemic control (HbA1c 7.5% and 11%) on insulin alone (n=141) or on insulin in combination with a stable dose of metformin (n=314). Saxagliptin 5 mg add-on to insulin with or without metformin provided significant improvements after 24 weeks in HbA1c and PPG compared with placebo add-on to insulin with or without metformin. Similar HbA1c reductions versus placebo were achieved for patients receiving saxagliptin 5 mg add-on to insulin regardless of metformin use (−0.4% for both subgroups). Improvements from baseline HbA1c were sustained in the saxagliptin add-on to insulin group compared to the placebo add-on to insulin group with or without metformin at Week 52. The HbA1c change for the saxagliptin group (n=244) compared to placebo (n=124) was -0.4% at Week 52.Saxagliptin add-on to thiazolidinedione therapy A placebo-controlled study of 24-week duration was conducted to evaluate the efficacy and safety of saxagliptin in combination with a thiazolidinedione (TZD) in patients with inadequate glycaemic control (HbA1c 7-10.5%) on TZD alone. Saxagliptin (n=183) provided significant improvements in HbA1c, FPG and PPG compared to placebo (n=180). Improvements in HbA1c, PPG and FPG following treatment with saxagliptin 5 mg were sustained up to Week 76. The HbA1c change for saxagliptin 5 mg (n=82) compared to TZD plus placebo (n=53) was -0.9% at Week 76. Patients with renal impairment A 12 week, multi-centre, randomised, double-blind, placebo controlled study was conducted to evaluate the treatment effect of saxagliptin 2.5 mg once daily compared with placebo in 170 patients (85 patients on saxagliptin and 85 on placebo) with type 2 diabetes (HbA1c 7.0-11%) and renal impairment (moderate [n=90]; severe [n=41]; or ESRD [n=39]). In this study, 98.2% of the patients received other antihyperglycaemic treatments (75.3% on insulin and 31.2% on oral antihyperglycaemics; some received both). Saxagliptin significantly decreased HbA1c compared with placebo; the HbA1c change for saxagliptin was -0.9% at Week 12 (HbA1c change of -0.4% for placebo). Improvements in HbA1c following treatment with saxagliptin 2.5 mg were sustained up to Week 52, however the number of patients who completed 52 weeks without modification of other antihyperglycaemic treatments was low (26 subjects in the saxagliptin group versus 34 subjects in the placebo group). The incidence of confirmed hypoglycaemic events was somewhat higher in the saxagliptin group (9.4%) versus placebo group (4.7%) although the number of subjects with any hypoglycaemic event did not differ between the treatment groups. There was no adverse effect on renal function as determined by estimated glomerular filtration rate or CrCL at Week 12 and Week 52.Table 3 Key efficacy results of Onglyza 5 mg per day in placebo-controlled monotherapy trials and in add-on combination therapy trials | | Mean baseline HbA1c (%) | Mean change2 from baseline HbA1c (%) at Week 24 | Placebo-corrected mean change in HbA1c (%) at Week 24 (95% CI) | | MONOTHERAPY STUDIES | | | | | • Study CV181011 (n=103) | 8.0
| -0.5
| -0.6 (-0.9, -0.4)3 | | • Study CV181038 (n=69) | 7.9
| -0.7 (morning)
| -0.4 (-0.7, -0.1) 4 | | (n=70)
| 7.9
| -0.6 (evening)
| -0.4 (-0.6, -0.1) 5 | | ADD-ON/COMBINATION STUDIES | | | | | • Study CV181014: add-on to metformin (n=186)
| 8.1
| -0.7
| -0.8 (-1.0, -0.6)3 | | • Study CV181040: add-on to SU1 (n=250)
| 8.5
| -0.6
| -0.7 (-0.9, -0.6)3 | | • Study CV181013: add-on to TZD (n=183)
| 8.4
| -0.9
| -0.6 (-0.8, -0.4)3 | • Study CV181039: initial combination with metformin6 Overall population (n=306)
Baseline HbA1c 10% stratum (n=107)
• Study CV181057: add-on to insulin (+/-metformin)
Overall population (n=300)
|
9.4
10.8
8.7
|
-2.5
-3.3
-0.7
| -0.5 (-0.7, -0.4) 7-0.6 (-0.9, -0.3) 8 -0.4 (-0.6, -0.2)3 | n=Randomized patients (primary efficacy-intention-to-treat analysis) with data available.1Placebo group had uptitration of glibenclamidefrom 7.5 to 15 mg total daily dose.2 Adjusted mean change from baseline adjusted for baseline value (ANCOVA). 3 p<0.0001 compared to placebo. 4 p=0.0059 compared to placebo.5 p=0.0157 compared to placebo.6 Metformin was uptitrated from 500 to 2000 mg per day as tolerated.7 Mean HbA1c change is the difference between the saxagliptin+metformin and metformin alone groups (p<0.0001).8 Mean HbA1c change is the difference between the saxagliptin+metformin and metformin alone groups. Paediatric populationThe European Medicines Agency has deferred the obligation to submit the results of studies with Onglyza in one or more subsets of the paediatric population in the treatment of type 2 diabetes mellitus (see section 4.2 for information on paediatric use). | |