Atrasentan hydrochloride is an investigational endothelin receptor antagonist primarily being developed for the treatment of chronic kidney disease (CKD), particularly diabetic nephropathy. It works by selectively blocking endothelin type A (ETA) receptors, which helps reduce proteinuria, lower intraglomerular pressure, and slow the progression of kidney damage. Clinical trials have shown promising results in reducing albuminuria and preserving renal function in patients with type 2 diabetes and CKD. Although initially explored for oncology applications, such as inhibiting tumor growth in prostate cancer by disrupting endothelin-mediated pathways, the cancer program has been discontinued, with current focus on nephrology.