Sex differences in response to the endothelin receptor antagonist atrasentan in individuals with type 2 diabetes and chronic kidney disease: a post hoc analysis of the SONAR trial

Aims/hypothesis In the Study Of diabetic Nephropathy with AtRasentan (SONAR), the endothelin receptor antagonist (ERA) atrasentan slowed progression of chronic kidney disease (CKD) in individuals with type 2 diabetes. Pre-clinical research suggests sex-based differences in the endothelin system might influence the efficacy and safety of atrasentan. We therefore assessed the effects of atrasentan in men and women participating in SONAR. Methods SONAR was a double-blind, placebo-controlled trial that compared atrasentan 0.75 mg/day with placebo in individuals with type 2 diabetes and CKD (eGFR 25-75 ml/min per 1.73 m(2), urine albumin/creatinine ratio [UACR] 300-5000 mg/g). The primary endpoint was defined as the time from randomisation to the first occurrence of a doubling in serum creatinine or kidney failure (eGFR <15 ml/min per 1.73 m(2), chronic dialysis, kidney transplantation or death from kidney failure). Hospitalisation for heart failure was the secondary endpoint. We performed Cox proportional hazards regression analyses to compare the treatment effect of atrasentan between male and female participants on the risk of the composite kidney outcome as well as hospitalisation for heart failure. Additionally, differences between male and female participants in atrasentan plasma exposure and eGFR change were assessed using, respectively, a t test and linear mixed effect model. Results Among 3668 randomised participants, 946 (25.8%) were female. Atrasentan significantly reduced the risk of the composite kidney outcome in female participants (HR 0.46 [95% CI 0.28, 0.76]) but not in male participants (HR 0.83 [95% CI 0.65, 1.05]; p value for interaction 0.032). Atrasentan compared with placebo reduced eGFR decline to a greater extent in female than in male participants (treatment effect difference between male vs female participants -0.99 ml/min per 1.73 m(2), p value for interaction=0.020). The RR for hospitalisation for heart failure with atrasentan vs placebo was 1.14 (95% CI 0.74, 1.76) in male participants and 1.88 (95% CI 0.98, 3.63) in female participants (p value for interaction=0.217). Female participants also had significantly higher atrasentan plasma exposure than male participants (geometric mean AUC 54.5 vs 42.6 ng/mlxh; p<0.001). Conclusions/interpretation Atrasentan showed greater kidney protection in female than in male participants but also induced more heart failure events in the female participants. These data suggest that sex-specific dosing regimens may be considered to optimise ERA treatment.