Lower Urate Levels and Less Inflammation Could Be Key
How might SGLT2 inhibitors reduce the risk of gout? Multiple studies have linked the drugs to lower serum urate levels, Dr. Yokose said, but researchers often excluded patients with gout.
For a small new study presented at the 2023 annual meeting of the American College of Rheumatology but not yet published, Dr. Yokose and colleagues reported that patients with gout who began SGLT2 inhibitors had lower urate levels than those who began a sulfonylurea, another second-line agent for type 2 diabetes. During the study period, up to 3 months before and after initiation, 43.5% of patients in the SGLT2 inhibitor group reached a target serum urate of < 6 mg/dL vs. 4.2% of sulfonylurea initiators.
“The magnitude of this reduction, while not as large as what can be achieved with appropriately titrated urate-lowering therapy such as allopurinol or febuxostat, is also not negligible. It’s believed to be between 1.5-2.0 mg/dL among patients with gout,” Dr. Yokose said. “Also, SGLT2 inhibitors are purported to have some anti-inflammatory effects that may target the same pathways responsible for the profound inflammation associated with acute gout flares. However, both the exact mechanisms underlying the serum urate-lowering and anti-inflammatory effects of SGLT2 [inhibitors] require further research and clarification.”
Moving forward, she said, “I would love to see some prospective studies of SGLT2 inhibitor use among patients with gout, looking at serum urate and clinical gout endpoints, as well as biomarkers to understand better the beneficial effects of SGLT2 inhibitors as it pertains to patients with gout.”
In Lupus, Findings Are More Mixed
Studies of SGLT2 inhibitors have excluded patients with lupus, limiting insight into their benefits in that specific population, said Dr. Jorge of Massachusetts General Hospital and Harvard Medical School. However, “one small phase I/II trial showed an acceptable safety profile of dapagliflozin add-on therapy in adult patients with SLE,” she said.
Her team is working to expand understanding about the drugs in people with lupus. At the 2023 ACR annual meeting, she presented the findings of a study that tracked patients with SLE who took SGLT2 inhibitors (n = 426, including 154 with lupus nephritis) or DPP4 inhibitors (n = 865, including 270 with lupus nephritis). Patients who took SGLT2 inhibitors had lower risks of major adverse cardiac events (HR, 0.69; 95% CI, 0.48-0.99) and renal progression (HR, 0.71; 95% CI, 0.51-0.98).
“Our results are promising, but the majority of patient with lupus who had received SGLT2 inhibitors also had the comorbidity of type 2 diabetes as a separate indication for SGLT2 inhibitor use,” Dr. Jorge said. “We still need to study the impact of SGLT2 inhibitors in patients with SLE and lupus nephritis who do not have a separate indication for the medication.”
Dr. Jorge added that “we do not yet know the ideal time to initiate SGLT2 inhibitors in the treatment of lupus nephritis. Specifically, it is not yet known whether these medications should be used in patients with persistent proteinuria due to damage from lupus nephritis or whether there is also a role to start these medications in patients with active lupus nephritis who are undergoing induction immunosuppression regimens.”
However, another study released at the 2023 ACR annual meeting suggested that SGLT2 inhibitors may not have a beneficial effect in lupus nephritis: “We observed a reduction in decline in eGFR [estimated glomerular filtration rate] after starting SGLT2 inhibitors; however, this reduction was not statistically significant … early experience suggested marginal benefit of SGLT2 inhibitors in SLE,” researchers from Johns Hopkins University, and the University of Maryland, Baltimore, reported.
“My cohort is not showing miracles from SGLT2 inhibitors,” study lead author Michelle Petri, MD, MPH, of Johns Hopkins, said in an interview.
Still, new European Alliance of Associations for Rheumatology recommendations for SLE now advise to consider the use of the drugs in patients with lupus nephritis who have reduced eGFR. Meanwhile, “the American College of Rheumatology is currently developing new treatment guidelines for SLE and for lupus nephritis, and SGLT2 inhibitors will likely be a topic of consideration,” Dr. Jorge added.
As for mechanism, Dr. Jorge said it’s not clear how the drugs may affect lupus. “It’s proposed that they have benefits in hemodynamic effects as well as potentially anti-inflammatory effects. The hemodynamic effects, including reducing intraglomerular hyperfiltration and reducing blood pressure, likely have similar benefits in patients with chronic kidney disease due to diabetic nephropathy or due to lupus nephritis with damage/scarring and persistent proteinuria. Patients with SLE and other chronic, systemic rheumatic diseases such as ANCA [antineutrophilic cytoplasmic antibody]-associated vasculitis also develop kidney disease and cardiovascular events mediated by inflammatory processes.”