LISBON – Greater glycemic control and weight reductions were achieved by people with poorly controlled type 2 diabetes who used a fixed dual combination of a sodium-glucose cotransporter-2 (SGLT2) inhibitor and dipeptidyl peptidase 4 (DPP-4) inhibitor added to metformin compared with those who used a DPP-4 inhibitor plus metformin in a phase 3b study.
The addition of dapagliflozin/saxagliptin (Qtern, AstraZeneca) to metformin (DAPA/SAXA-MET) resulted in a 1.4% decrease in glycated hemoglobin A1c (HbA1c) from baseline to week 26, which was 0.3% more than the 1.1% drop seen when sitagliptin (Januvia, Merck) was added onto metformin (SITA-MET; P less than .008).
“With the triple therapy there was a more profound reduction in glycated hemoglobin,” , MD, professor of endocrinology and metabolism and chief of the section of diabetes at the University of Pisa, Italy, reported at the annual meeting of the European Association for the Study of Diabetes. “Triple therapy was also associated with significant reductions in fasting plasma glucose and body weight versus sitagliptin added on to metformin,” he said.
Of note, a higher percentage of patients given the triple therapy achieved a target HbA1c of less than 7% compared with those receiving the dual therapy (37% vs. 25%; P = .0034) at 26 weeks, and fasting plasma glucose also fell to a greater extent (–32 mg/dL vs. –11 mg/dL; P less than .0001).
“This study beautifully illustrates to me that when we treat use SGLT2 inhibitors we shouldn’t be just fixated by the glycemic difference,” , MD, professor of cardiovascular and medical sciences at the University of Glasgow, Scotland, said from the audience.
Dr. Sattar, who was not involved in the study, suggested that the diabetes community was at the point of a new paradigm: “We could use these drugs to protect the kidneys and the heart,” he suggested. “As a diabetes community we should move beyond glycemia; it’s the other benefits that we should be thinking about when we prescribe these drugs,” he said.
Not everyone was as enthusiastic. One delegate said the study design was “screwy” because two different DPP-4 inhibitors were used. Dr. Del Prato responded, saying that the dual sitagliptin/metformin combination was the comparator arm because it was the most commonly used combination, and saxagliptin was used as it was available in a fixed combination with a DPP4 inhibitor, dapagliflozin.
“Current guidelines recommend addition of a single antidiabetes agent to metformin to achieve and maintain glycemic targets in patients with type 2 diabetes; however, responses to dual therapy are often limited and not persistent in time,” Dr. Del Prato observed. He added that there was already some evidence that triple drug combinations with complementary modes of action “provide increased efficacy for some patients” and that both SGLT2 inhibitors and DPP-4 inhibitors were recommended in combination with metformin.
The aim of the randomized, double-blind, double-dummy study he presented, therefore, was to compare the efficacy and safety of adding the combination of an SGLT2 (dapagliflozin) plus a DPP-4 inhibitor (saxagliptin) versus adding a DPP-4 inhibitor (sitagliptin) alone to metformin “across diverse predefined subpopulations of patients with inadequately controlled type 2 diabetes.”
Patients recruited into the trial had to have been taking a stable dose of metformin of more than 1,500 mg/day for at least 8 weeks at study entry, with a baseline HbA1c of 8%-10.5%, and a fasting plasma glucose of 270 mg/dL or less. Of 861 people screened, 461 were randomized, with 232 receiving daily treatment with the fixed combination of DAPA (10 mg) plus SAXA (5 mg) and 229 receiving sitagliptin (100 mg) added to their existing metformin regimen.
A higher rate of completion (92% vs. 86%) was seen with triple therapy than with the dual therapy, although reasons for discontinuation were similar between the groups. Both triple and dual therapy were “well tolerated,” Dr. Del Prato reported. The rates of any adverse event (AE), drug-related AEs, serious AEs, and drug-related serious AEs were a respective 48.7% vs. 47.6%, 7.2% vs. 6.6%, 2.2% vs. 3.9%, and 0% vs. 0.4%.
“No patient experienced a major episode of hypoglycemia,” Dr. Del Prato said, noting that 3.9% of the triple-therapy-treated versus 2.6% of the dual-therapy-treated subjects experienced this AE.
Urogenital infections were “infrequent” with a “similar incidence of genital infections” at 2.6% for the triple therapy group and 2.2% for the double therapy group. Urinary tract infections occurred “slightly more frequently” with the triple than dual regimen, at 4.7% vs. 2.2%, respectively.
“Improvements in glycated hemoglobin, with the addition of once-daily dapagliflozin and saxagliptin to metformin were greater than with the addition of sitagliptin alone on top of metformin and were achieved regardless of baseline A1c, age, gender, race, and region,” Dr. Del Prato said. Patients will continue to be followed in the trial for 1 year and results of this extension phase of the study will provide information on the durability of responses to DAPA/SAXA/MET versus SITA/MET.
AstraZeneca funded the study. Dr. Del Prato disclosed ties with AstraZeneca, Boehringer Ingelheim, Merck Sharpe & Dohme, Novartis, Eli Lilly, GlaxoSmithKline, Hanmi Pharmaceuticals, Intarcia Therapeutics, Janssen Pharmaceuticals, Novo Nordisk, Sanofi-Aventis, Servier, and Takeda Pharmaceuticals. Dr. Sattar disclosed ties with Amgen, Boehringer Ingelheim, Eli Lilly, Janssen, and Novo Nordisk.