Nat. Rev. Nephrol. doi:10.1038/nrneph.2015.206 Figure 2 Considerations in the design of trials for immune-mediated kidney disease Figure 2 | Considerations in the design of trials for immune-mediated kidney disease. The type of trial should depend on the presumed mechanism of action of the test agent (1), for example, an induction trial design should be used for agents that are expected to induce remission. Trial end points must be consistent with regulatory requirements for drug approval; however, they must also reflect the expected outcomes based on the presumed mechanism of action of the drug (2). Preservation of kidney function could, for instance, be achieved by decreasing inflammation or preventing scarring, and clinical markers such as proteinuria and haematuria could therefore be assessed. Biomarkers that are specific for inflammation or fibrosis would be useful. Trial duration is often constrained by logistical and financial considerations; however it must be sufficient to establish the effect of the novel agent (3). Use of background medications should be dictated by the severity and speed of the disease process and the availability of therapies to adequately treat the disease (4). The potential of background therapy to obscure results must be considered. Criteria for patient inclusion must be based on the preceding considerations, histologic, clinical and molecular validation of the disease if possible, whether disease duration and/or prior use of therapies could confound the results, and importantly, if the novel agent has a clear target, such as a specific cytokine, patients should display elevated levels of that target at enrolment (5). CV, cardiovascular; GFR, glomerular filtration rate; SCr, serum creatinine; SLE, systemic lupus erythematosus. Anders, H.-J. et al. (2016) Hurdles to the introduction of new therapies for immune-mediated kidney diseases Nat. Rev. Nephrol. doi:10.1038/nrneph.2015.206