Cardiovascular outcome trials show the way
In the context of antihyperglycemic drugs, the “cardiovascular outcome trials” refers to a series of large trialsby the Food and Drug Administration in 2008 to assess the cardiovascular disease effects of new agents coming onto the U.S. market to treat type 2 diabetes mellitus (T2DM). By the time Dr. Verma spoke at the AHA meeting, he could cite reported results from 12 of these trials: 5 different drugs in the GLP-1 RA class, 4 drugs in the dipeptidyl peptidase-4 (DPP-4) inhibitor class, and 3 drugs from the SGLT2 inhibitor class. Dr. Verma summed what the findings have shown.
The four tested DDP-4 inhibitors (alogliptin, linagliptin, saxagliptin, and sitagliptin) consistently showed neutrality for the primary outcome of major adverse cardiovascular disease events (MACE), constituted by cardiovascular disease death, MI, or stroke.
The five tested GLP-1 RAs (albiglutide, exenatide, liraglutide, lixisenatide, and semaglutide) showed a mixed pattern of MACE results that seemed to be linked with the subclass the drug fell into. The two exedin-4–based drugs, exenatide and lixisenatide, each showed a statistically neutral effect for MACE, as well as collectively in a combined analysis. In contrast, three human GLP-1–based drugs, albiglutide, liraglutide, and semaglutide, each showed a consistent, statistically-significant MACE reduction in their respective outcome trials, and collectively they showed a highly significant 18% reduction in MACE, compared with placebo, Dr. Verma said. Further, recent analysis by Dr. Verma that used data from liraglutide treatment in thetrial showed the MACE benefit occurred only among enrolled patients treated with liraglutide who had established atherosclerotic cardiovascular disease (ASCVD). Patients enrolled in the trial with only multiple risk factors (in addition to having T2DM) but without established ASCVD showed no significant benefit from liraglutide treatment for the MACE endpoint, compared with control patients.
Recently a press-release announcement of results from a sixth GLP-1 RA, dulaglutide, in thetrial of MACE outcomes suggested that a drug in this class could have broader effect. The majority, 69%, of the 9,901 patients with T2DM enrolled in REWIND had risk factors but not established ASCVD at enrollment. A Nov. 5, 2018, from the company developing this drug, Lilly, reported that the study overall produced a statistically significant reduction in MACE, although it provided no additional details. As the released noted, this made REWIND the first trial to show a MACE benefit from a drug in the GLP-1 RA class in patients without established ASCVD.
The MACE outcome results from the three SGLT2 inhibitor trials showed a similar pattern as liraglutide: In patients with established ASCVD, the drugs individually each produced a MACE reduction, although dapagliflozin just missed having a statistically significant reduction. Collectively, the three drugs showed a statistically significant, 14% relative risk reduction for MACE, compared with control patients. But among patients with multiple risk factors only, but without established ASCVD, included in two of the three trials (CANVAS and DECLARE-TIMI 58), the results showed both individually and collectively a neutral MACE effect.
But unlike the other antihyperglycemic drugs tested in the cardiovascular outcome trials, the SGLT2 inhibitors have shown two additional, highly important secondary outcomes: a consistent reduction in hospitalization for heart failure and a consistent reduction in renal-disease progression.
A meta-analysis of the three SGLT2 inhibitor trials published coincident with the release of the DECLARE-TIMI 58 results showed that, for the outcome of either cardiovascular death or hospitalization for heart failure, the SGLT2 inhibitors collectively showed a significant 29% relative decrease in this incidence among patients with a history of heart failure, and a significant 21% relative decrease among patients without history of heart failure (Lancet. 2018 Nov 10.). Among the subset of patients with established ASCVD, treatment with a SGLT2 inhibitor across all three trials showed a significant 16% relative risk reduction, and in the subset with multiple risk factors but no established ASCVD, the two SGLT2 inhibitors collectively produced a 16% relative cut in cardiovascular death or heart failure hospitalization with a P value of .06. Finally, the Lancet meta-analysis showed that, for a combined endpoint that reflected renal worsening, the SGLT2 inhibitors showed a significant relative reduction of about 45% in both the subgroup of patients with established ASCVD and in the subgroup of those with just risk factors.
“This is a big step forward for patients with multiple risk factors and diabetes but without ASCVD, that both renal disease and hospitalization for heart failure are sensitive” to the SGLT2 inhibitors, Dr. Verma noted. “We see renal protection and reduction of heart failure hospitalization across both primary and secondary prevention patients, with no need to distinguish them based on ASCVD.” In contrast, he noted, the MACE benefit from the SGLT2 inhibitors seems limited to patients with ASCVD. The day before making this point in a talk during the meeting, Dr. Verma had published the same message in a commentary (Lancet. 2018 Nov 10.).
Although the “nomenclature of primary versus secondary prevention is appropriate for atherosclerotic outcomes, it is likely to be inappropriate for a person with type 2 diabetes who is at risk of hospitalization for heart failure and renal disease,” Dr. Verma wrote with his associates in the commentary.