Development and Validation of HistoMX, a Gene-Expression Platform for Molecular Interpretation of Kidney Allograft Biopsies

This retrospective multicentre observational study developed and validated HistoMX, an automated gene-expression-based platform for multidimensional molecular interpretation of kidney allograft biopsies. The study included 2,410 archived post-transplant kidney allograft biopsy samples from adult kidney transplant recipients. Formalin-fixed paraffin-embedded biopsy tissue was profiled using the Banff Human Organ Transplant panel on the NanoString nCounter platform. HistoMX integrates locked preprocessing, quality control, single-sample normalization, diagnostic classification, Banff lesion-level modelling, molecular lesion-severity scores, composite injury indices, immune-cell estimation, pathway-enrichment analysis, and automated clinician-facing reporting. The platform was evaluated against reference histology based on the Banff classification. HistoMX was designed to complement, not replace, conventional histopathology by providing standardized molecular evidence across diagnostic, lesion-level, continuous injury, and biological dimensions of kidney allograft injury.