A Study to Determine if BHV-1400 is Effective and Safe in Adults With IgA Nephropathy

Any secondary IgAN as defined by the Investigator; secondary IgAN can be associated with cirrhosis, celiac disease, HIV infection, herpetiformis, seronegative arthritis, small-cell carcinoma, lymphoma, disseminated tuberculosis, bronchiolitis obliterans, inflammatory bowel disease, familial Mediterranean fever, etc. NOTE: IgA Vasculitis excluded if patient has had any IgA Vasculitis related extrarenal signs or symptoms, or requirement for steroid or other immunosuppressive therapy in the past year.

Any cause of chronic kidney disease that is not diagnosed as IgAN or may be due to non-IgAN cause, such as diabetic nephropathy. If presence of other kidney disease or concurrent glomerulopathies felt to be non-dominant, consideration for inclusion must be discussed with and approved by the Sponsor Medical Monitor/Sponsor Designee.

Presence of rapidly progressive glomerulonephritis as defined by 50% decline in eGFR within 3 months prior to Screening.

Evidence of nephrotic syndrome, defined as 24-hour protein > 3.5g with concurrent hypoalbuminemia (Albumin < 3.0 g/dl), within 6 months of Screening