The idea of individualizing therapies to obtain optimal clinical results is not new but has only recently been applied to kidney diseases. Nonetheless, kidney disorders present a variety of opportunities to personalize medicine. Here, the heterogeneity of kidney disorders is reviewed to provide a rationale for pursuing personalized medicine. Data on adjusting therapy on the basis of pharmacogenetics/genomics and pharmacodynamics are summarized to demonstrate where the field is, and biomarker studies that reflect the future of personalized medicine are discussed. The goal of this review is to demonstrate that we can personalize therapy for kidney diseases but that considerable investment in new research will be required for personalized medicine to be routinely used in nephrology clinics. Clin J Am Soc Nephrol 4: 1670 -1676. doi: 10.2215 T he phrase personalized medicine has been used with increasing frequency in the lay press, and academia has embraced this concept by forming centers of personalized medicine within their health systems. The goal of determining the right drug, for the right patient, at the right time is not new, however, and has been actively pursued for some time in oncology using genomic tools to look for gene mutations or variations in gene expression that may affect therapy. Other disciplines, including nephrology, have joined this endeavor, although the data on personalized therapies for kidney diseases are still very preliminary. This mini-review presents these data to provide a framework for expanding research into individualized therapies for kidney diseases.
Building a Case for Personalized Medicine in Kidney DiseasesThere is ample evidence that kidney disorders that are characterized by a specific constellation of clinical signs and symptoms display the molecular and biochemical heterogeneity that lends itself to individualized medicine. For example, despite similar clinical and histologic phenotypes, pediatric allograft rejection could be divided into three molecular groups by microarray analysis of total renal biopsy RNA expression (1). One of these acute rejection molecular groups was enriched for expression of B cell genes, and by immunohistochemistry, abundant B cells were found to be present in renal biopsy tissue from this subset of patients. Although the numbers were small, recovery from rejection and steroid responsiveness were significantly better in the patients who did not have B cells infiltrating their allografts. These data suggest that determining the molecular subtype of acute rejection before treatment may be used to identify patients who are likely to be steroid resistant and who may benefit from a different antirejection protocol (2).Molecular heterogeneity is also found in primary and secondary glomerular diseases. Pediatric patients who had FSGS and displayed nephrotic-range proteinuria or renal insufficiency could be differentiated from patients who did not have nephrosis or renal insufficiency, respectively, on the basis of unique renal cortical RNA expression (3...