P04-17 Cross-Species Immunoassays for Detection of Translational Safety Biomarkers in Drug-Induced Kidney Injury

Drug-induced kidney injury (DIKI) represents a major challenge in drug safety assessment, underscoring the need for robust and translational biomarker assays that are applicable across multiple preclinical species and humans. Sandwich immunoassays rely heavily on the availability of specific antibodies, which are often time-consuming and costly to develop. A key limitation is the lack of cross-reactivity of many antibodies between preclinical species and humans, which hampers streamlined assay development for comparative toxicology studies. TXP antibodies offer an effective solution for cross-species peptide enrichment by targeting conserved C-terminal peptide sequences of biomarker-derived peptides generated after enzymatic proteolysis. Their defined epitope specificity enables capture of peptides from the same biomarkers across species, including humans and common preclinical models. When combined with immunoaffinity liquid chromatography – tandem mass spectrometry (IA-LC-MS/MS), this approach enables highly sensitive and specific quantification without requiring species-specific antibodies or extended assay development timelines. Analytical specificity is further enhanced through the use of stable isotope-labeled internal standard peptides. Using this strategy, we rapidly developed quantitative IA-LC-MS/MS assays for FDA-qualified DIKI biomarkers – including kidney injury molecule-1 (KIM-1), clusterin, neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN), cystatin C (CST3), alpha-1-microglobulin (A1M), and retinol binding protein 4 (RBP4) – in urine from humans, monkeys, rats, and dogs. Here, we present comprehensive development and validation data demonstrating the performance, reproducibility, and cross-species applicability of these assays, highlighting their value for translational safety biomarker applications in drug development.