Pirfenidone to Treat Kidney Disease (Focal Segmental Glomerulosclerosis)

INCLUSION CRITERIA: Adults greater than or equal to 18 years of age. Patients will provide informed consent. Biopsy proven FSGS. Glomerular filtration rate of at least 25 and no more than 80 ml/minute as assessed by the 4 variable Modification of diet in renal disease GFR equation. At least 6 months of renal function data must be available prior to the patient's receiving pirfenidone, and renal function must show a rate of decline of greater than or equal to 0.4 ml/min/month during this baseline period. Patients must have received no glucocorticoids, cyclophosphamide, mycophenolate or other immunosuppressive drugs for at least 2 months prior to the study period. Patients must have received no cyclosporin for at least 6 months prior to the study period. Patients must have been taking an angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) at a stable dose for at least 6 months, unless intolerant of both classes of medication. Patients who are HIV seropositive will receive standard care for HIV disease (patients receiving immune-modulating therapy will be excluded). Women with child-bearing potential must maintain an effective birth control regimen (oral contraceptive, intrauterine device, barrier plus spermicide). Men will be advised that although Ames testing has been negative for any evidence of mutagenicity, they should consider use of contraceptives during the study period as well. EXCLUSION CRITERIA: Inability to give informed consent or cooperate with study. Known intolerance to pirfenidone. Evidence of FSGS associated with an additional primary or secondary glomerular disease (e.g. diabetes, membranous nephropathy, IgA nephropathy). Recent (within 6 months) history of myocardial infarction. History of peptic ulcer within 6 months. History of cerebrovascular disease manifested by transient ischemic attack or cerebrovascular accident within 6 months. Pregnancy, breast feeding or inadequate birth control. History of photosensitivity dermatitis. Concurrent drug treatment with gemfibrozil, cyclosporin or erythromycin, potassium-sparing diuretics and other drugs which may potentiate hyperkalemia, or concurrent immunosuppresive medications. Requirement for NSAID therapy. Requirement for interleukin-2 therapy or other immune-modulating medication. Existence of any other condition which would complicate the implementation or interpretation of the study. Renal transplant. Evidence of significant hepatic disease, as indicated by serum transaminases greater than 3 times upper limit of normal, protime greater than 2 seconds prolonged.