iMDx GraftAssure matches NGS rival in kidney transplant study
Insight Molecular Diagnostics (Nasdaq: IMDX) has announced the publication of a head-to-head comparison of its GraftAssure digital PCR assay against a competing next-generation sequencing kit in Clinical Chemistry, the peer-reviewed journal of the Association for Diagnostics and Laboratory Medicine. The study, conducted with researchers at Heidelberg, reports 99.2% agreement between the two platforms at the 0.5% clinical threshold used to assess kidney transplant rejection risk.
The paper concludes that the two established methods for quantifying donor-derived cell-free DNA (dd-cfDNA) demonstrate "excellent diagnostic agreement," supporting flexibility in assay selection based on availability and cost. The authors describe the findings as supporting broader integration of dd-cfDNA testing into routine clinical practice.
Analytical differentiation
Beyond concordance, the study highlights a specific area where GraftAssure's droplet digital PCR (ddPCR) approach outperformed the NGS comparator. The reference change value (RCV), a measure of the minimally significant difference between two serial measurements in the same patient, was calculated at 41% for GraftAssure at a median dd-cfDNA level of 0.17%. The RCV could not be calculated for the NGS assay because more than half of measurements in the comparison cohort fell below that platform's lower limit of quantification.
GraftAssure's lower limit of quantification is stated at 0.04% dd-cfDNA, compared with published figures of 0.12% to 0.23% for NGS-based technologies. The company says this sensitivity advantage is particularly relevant for monitoring organs such as the heart, where circulating dd-cfDNA levels are characteristically low.
Chief Science Officer Dr Ekkehard Schuetz said the tight correlation across all biopsy-proven pathology categories, classified under the BANFF 2022 schema, "confirms the clinical interchangeability of both methods," while pointing to digital PCR's "improved analytical sensitivity" in detecting low-quantity dd-cfDNA as an additional advantage.
Chief executive Josh Riggs noted the company's plans to use the data to support a regulatory submission in the European Union, building on the Heidelberg collaboration.
Regulatory and market context
iMDx is currently seeking FDA marketing authorisation for GraftAssureDx, its in vitro diagnostic kit version of the technology, intended for decentralised use in hospital-based transplant laboratories. Its existing GraftAssureCore product operates as a laboratory-developed test reimbursed by CMS and run at the company's CLIA-certified facility in Franklin, Tennessee.
The dd-cfDNA transplant monitoring market has been shaped primarily by centralised, send-out laboratory models. A shift toward local, kit-based testing represents a meaningful commercial and logistical change, and several academic and commercial groups are pursuing similar approaches. The clinical and economic case for decentralisation rests on turnaround time and cost, both of which iMDx cites as drivers for its kit strategy.
iMDx will present findings from the study at the American Transplant Congress in Boston, running from 20 to 24 June 2026. The data were first presented at the European Renal Association and European Society of Organ Transplantation meetings in 2025. Investors will be watching for a timeline and scope for the EU regulatory submission, as well as updates on the FDA review process for GraftAssureDx.