The present invention relates to methods of delaying progression to end stage renal disease (ESRD) in patients comprising administration of 1-(2-ethoxyethyl)-5-(ethyl(methyl)amino)-7-((4-methylpyridin-2-yl)amino)-N-(methylsulfonyl)-1H-pyrazolo[4,3-d]pyrimidine-3-carboxamide. The present invention also includes administration of pharmaceutical compositions for delaying progression to ESRD.1-(2-ethoxyethyl)-5-(ethyl(methyl)amino)-7-((4-methylpyridin-2-yl)amino)-N-(methylsulfonyl)-1H-pyrazolo[4,3-d]pyrimidine-3-carboxamide
