Efficacy and safety of monotherapy with the novel sodium/glucose cotransporter-2 inhibitor tofogliflozin in Japanese patients with type 2 diabetes mellitus: a combined Phase 2 and 3 randomized, placebo-controlled, double-blind, parallel-group comparative study

Abstract

Background: In recent years, several oral antidiabetic drugs with new mechanisms of action have become available, expanding the number of treatment options. Sodium/glucose cotransporter-2 (SGLT2) inhibitors are a new class of oral antidiabetic drugs with an insulin-independent mechanism promoting urinary glucose excretion. We report the results of a combined Phase 2 and 3 clinical study (Japic CTI-101349) of the SGLT2 inhibitor tofogliflozin (CSG452, RG7201) in Japanese patients with type 2 diabetes mellitus.

Methods: The efficacy and safety of tofogliflozin were assessed in this multicenter, placebo-controlled, randomized, double-blind parallel-group study involving 230 patients with type 2 diabetes mellitus with inadequate glycemic control on diet/exercise therapy. Between 30 October 2010 and 28 February 2012, patients at 33 centers were randomized to either placebo (n = 56) or tofogliflozin (10, 20, or 40 mg; n = 58 each) orally, once daily for 24 weeks. The primary efficacy endpoint was the change from baseline in HbA1c at week 24.

Results: Overall, 229 patients were included in the full analysis set (placebo: n = 56; tofogliflozin 10 mg: n = 57; tofogliflozin 20 and 40 mg: n = 58 each). The least squares (LS) mean change (95% confidence interval) from baseline in HbA1c at week 24 was -0.028% (-0.192 to 0.137) in the placebo group, compared with -0.797% (-0.960 to -0.634) in the tofogliflozin 10 mg group, -1.017% (-1.178 to -0.856) in the tofogliflozin 20 mg group, and -0.870% (-1.031 to -0.709) in the tofogliflozin 40 mg group (p < 0.0001 for the LS mean differences in all tofogliflozin groups vs placebo). There were also prominent decreases in fasting blood glucose, 2-h postprandial glucose, and body weight in all tofogliflozin groups compared with the placebo group. The main adverse events were hyperketonemia, ketonuria, and pollakiuria. The incidence of hypoglycemia was low. Furthermore, most adverse events were classified as mild or moderate in severity.

Conclusions: Tofogliflozin 10, 20, or 40 mg administered once daily as monotherapy significantly decreased HbA1c and body weight, and was generally well tolerated in Japanese patients with type 2 diabetes mellitus. Phase 3 studies were recently completed and support the findings of this combined Phase 2 and 3 study.

Trial registration: This study was registered in the JAPIC clinical trials registry (ID: Japic CTI-101349).

Figure 1

Study design. Patients underwent initial screening tests and those who met the inclusion criteria were provisionally registered. Patients then entered a second screening phase and those who still met the inclusion criteria were accepted for final registration and were randomized. The overall screening period was 8 weeks. An additional visit was arranged for patients who discontinued the study.

Figure 2

Mean change (LS mean) in HbA_1c from baseline to time of visit. Mean changes (LS mean and 95% CI) in HbA_1c from baseline to time of visit for each treatment group (placebo, tofogliflozin 10, 20 or 40 mg) in the FAS (with LOCF) were plotted. Mean change from baseline in HbA_1c at week 24 (LS mean) and LS mean difference versus placebo are shown in the table below the graph. LS means, LS mean differences and 95% CI were estimated using an ANCOVA model with treatment groups (placebo and tofogliflozin 10, 20, or 40 mg) as a fixed effect and baseline HbA_1c and gender as covariates.

Figure 3

Mean change (LS mean) in body weight from baseline to time of visit. Mean changes (LS mean and 95% CI) in body weight from baseline to time of visit for each treatment group (placebo, tofogliflozin 10, 20 or 40 mg) in the FAS (with LOCF) were plotted. Mean change from baseline in body weight at week 24 (LS mean) and LS mean difference versus placebo are shown in the table below the graph. LS means, LS mean differences and 95% CI were estimated using an ANCOVA model with treatment groups (placebo and tofogliflozin 10, 20, or 40 mg) as a fixed effect and baseline body weight as a covariate. Among the tofogliflozin groups, the tofogliflozin 40 mg group had the greatest decrease.

Figure 4

Mean changes in fasting plasma glucose from baseline to week 24 by baseline fasting blood glucose tertile. The mean change in fasting blood glucose from baseline to week 24 tended to increase with higher baseline fasting blood glucose tertile (T).