Can Dapagliflozin Preserve Structure and Function in Transplanted Kidneys?

This is a randomized, placebo-controlled trial with dapagliflozin 10 mg vs. placebo o.d. in kidney transplant patients. The patients are randomized 1:1 to active: placebo treatment 6 weeks after transplantation and followed for a total of 150 weeks (156 weeks post-transplant).

Before treatment initiation (6 weeks after transplantation) the following investigations will be performed;

1. Estimated GFR: Assessed using the Modification of Diet in Renal Disease 4 (MDRD-4) formula and is presented as mL/min/1.73 m2. Plasma creatinine concentrations are to be analyzed at the Department of Medical Biochemistry where the patient is followed and is presented as mmol/L. (Estimated GFR will be calculated from at least 4 plasma creatinine measurements per year).
2. Blood sample: Measured variables include plasma creatinine, hemoglobin, hematocrit, sodium, potassium, magnesium and uric acid.
3. Kidney tissue analyses: a.) Light microscopical evaluation in formalin-fixed and paraffin-embedded (FFPE) kidney graft biopsies: Semi-quantitative estimation of percent graft fibrosis in the renal cortex according to the Banff classification, percent interstitial fibrosis and percent inflammation outside fibrotic scars. b.) Immunohistochemistry: Graft samples will be deparaffinized and boiled in antigen retrieval solution and then exposed to primary antibodies against collagen and extracellular matrix markers, e.g. periostin, tenascin and picrosirius red. In addition, p16INKa, a marker of premature aging, and endothelial markers to evaluate capillary density will be used.

c.) Samples will be digitally scanned to perform digital morphometric evaluation using the softwares 3D Histech, Analysis Pro and QuPath. Areas not of interest (renal medulla, scar tissue, capsule or subscapular areas), poor quality scans and artefacts will be excluded. Digital software will also be used to estimate glomerular volume and mesangial volume fraction using QuPath. All evaluations will be performed by investigators blinded for the study participants' identity and clinical data. This is an explorative study, and no power estimate is available.

d.) The investigators will also perform molecular analyses, mRNA and proteomics in a subsample (n=25 in intervention, n=25 in control group, matched for age, gender and eGFR as appropriate) at the same two time-points as described above (altogether n=100 biopsies processed for RNA sequencing and proteomics), using standard bulk mRNA/miRNA sequencing and proteomics of whole sections from 'RNA later' kidney graft biopsies (Genomics and Proteomics Core Facilities, UiO). The investigators will also perform bioinformatic analyses focusing on fibrosis. 4. Oral glucose tolerance test (OGTT): Will be performed in persons not on glucose-lowering treatment by ingestion of 75 g glucose dissolved in water (or 1 g/kg if body weight is <75 kg). Blood samples for measurements of glucose, insulin and C-peptide are collected at 0, 30 and 120 min, respectively. Glucose tolerance is assessed by the 2-h glucose value, while first phase insulin release is primarily reflected by the 30 min insulin value which is included in the Stumvoll equation which measures both first and second phase insulin release. Insulin sensitivity will be assessed by the Matsuda equation. 5. Protein/creatinine ratio: Will be assessed at the Department of Medical Biochemistry where the patient is followed. Open urinary stix is not considered appropriate, partly due to the risk of unblinding in case of glucosuria detection by a combined stix. (Protein/ creatinine ratio will be collected from at least 4 urine sample measurements per year) 6. Blood Pressure: Will be assessed as both systolic and diastolic measure, and measurements are performed according to standard procedures (measured in mmHg ). The same standard will be followed for blood pressure measurements at the local hospitals. 7. Metabolomics: Urine and serum will be sent on dry ice in larger batches. LC-MS methodology will be used for the analysis, using a commercial kit (Biocrates). ELISA methodology will in addition be used in case verification analyses are necessary. This exploratory analysis will focus on markers for fibrosis, inflammation and secretion function in the kidney tubuli.