IMDX GraftAssure CM-Score lifts kidney rejection PPV to 81%
Insight Molecular Diagnostics (Nasdaq: IMDX) has published data in the American Journal of Transplantation showing that its GraftAssure Combination Model score, or CM-Score, delivers superior diagnostic performance to either fractional or absolute measurement of donor-derived cell-free DNA used alone in kidney transplant rejection monitoring.
The CM-Score combines both the percentage and absolute copy-per-millilitre measurements of dd-cfDNA in a single mathematical model. Validated across 106 rejections and 308 non-rejections, the score returned a positive predictive value of 81% (72%–89%) compared with a weighted-average PPV of 54% across six published cohorts, while retaining a negative predictive value of 91%. Decision curve analysis showed a statistically significant net benefit over conventional single-metric approaches, with P values below 0.003.
Clinical significance
The practical implication is meaningful. In transplant medicine, a low PPV means many patients flagged by a test as likely rejecting are in fact not, driving unnecessary biopsies with their attendant risks and costs. Doubling the PPV, as IMDX claims, would allow transplant physicians to use a positive GraftAssure result to guide biopsy decisions with considerably greater confidence while retaining the high rule-out power needed to avoid missing genuine rejection episodes.
Chief Science Officer Prof. Dr. Ekkehard Schuetz said the CM-Score gives transplant physicians a tool capable of distinguishing rejection from other common pathologies "with high and unprecedented rule-in and retained high rule-out power," which he described as "an exceptionally useful new tool for the daily clinical challenges after kidney transplantation." The data were first presented in late-breaking form at the World Transplant Congress in August 2025 and will be shared again at the American Transplant Congress in Boston from 20 to 24 June 2026.
IMDX is now running the GALACTIC prospective registry study to confirm the findings, evaluate their impact on biopsy and immunosuppression decisions, and build long-term outcomes evidence to support broader clinical adoption of the CM-Score.
Regulatory and competitive context
The company's broader commercial ambition sets it apart from the current centralised-laboratory model that dominates dd-cfDNA testing. IMDX is developing GraftAssureDx as an in-vitro diagnostic kit intended for use directly in hospital transplant centre laboratories, a decentralised model that would reduce turnaround times compared with send-out testing. The company is seeking FDA marketing authorisation for that kit; the product remains investigational and has not yet been cleared or authorised for marketing.
The dd-cfDNA transplant monitoring market is already served by established laboratory-developed tests, including CareDx's AlloSure, which has accumulated substantial clinical evidence and CMS reimbursement. IMDX's GraftAssureCore is also currently reimbursed by CMS and run at its CLIA-certified laboratory in Franklin, Tennessee, giving it a foothold before the kit-based IVD is approved. Whether the CM-Score's improved PPV translates into clinical practice change will depend on the GALACTIC registry results and on how payors weigh the additional diagnostic performance against existing reimbursed options.
The peer-reviewed publication in the American Journal of Transplantation provides a level of external validation that press-release data alone does not, though the study design, drawn from a sub-cohort for model derivation and validated in a separate cohort, will be subject to independent scrutiny as the dataset is more widely reviewed. Investors and clinicians should note that full FDA authorisation, prospective registry completion, and payor coverage decisions all remain ahead for IMDX's kit-based commercial model.