44 patients will be centrally randomized by computer assignment between two study arms (Bortezomib versus Placebo) using a 1:1 randomization scheme. To avoid the bias of unbalanced baseline variables that potentially affect treatment responses, stratification will be performed for eGFR (> versus <50 ml/min/1.73 m2) and the presence or absence of Banff I T-cell-mediated rejection (index biopsy).