The assay is designed to allow transplant centers to perform molecular monitoring for organ rejection in-house rather than using send-out laboratories.

Insight Molecular Diagnostics Inc (iMDx) has submitted its GraftAssureDx assay to the Food and Drug Administration (FDA) for regulatory review. The company states the submission represents the first kitted donor-derived cell-free DNA (dd-cfDNA) assay to seek FDA authorization.

The assay is designed to assess the likelihood of transplanted organ rejection by measuring DNA fragments from the donor organ that circulate in the recipient’s bloodstream. While dd-cfDNA testing is currently available through centralized laboratory send-out models, the iMDx kit is intended to enable transplant centers to perform the testing in-house.

The submission is a de novo request. The FDA typically follows a 150-day review process for such submissions, and the company expects a potential authorization within the 2026 calendar year.

“We have made a review-ready submission with sufficient analytical data and clinical evidence to support that our assay is safe and effective for using the fractional measurement of dd-cfDNA to assess the likelihood of transplanted organ rejection,” says the iMDx leadership team, in a release.

Technical Performance and Clinical Utility

The technology measures both absolute quantities of organ DNA fragments and their relative quantities. This combination, known as a CM-score, is intended to improve the detection of t-cell mediated rejection (TCMR). According to the company, TCMR can sometimes be difficult to identify when dd-cfDNA is expressed only as a percentage because infiltrating recipient immune cells can dilute the relative donor fraction.

By quantifying the absolute amount of dd-cfDNA, which remains unaffected by increases in recipient DNA, the assay may provide a more accurate measure of rejection risk. This dual-measurement approach is also intended to improve the positive predictive value of testing, potentially helping clinicians avoid unnecessary biopsies.

In February 2026, data from a head-to-head study was presented at the Cutting Edge of Transplantation conference. The study compared the iMDx technology with a leading centralized testing competitor, with the independent hospital concluding the results were favorable for the in-house assay.

“Our assay was used in monitoring the transplanted organ health in the ‘groundbreaking’ New England Journal of Medicine study published in 2024, which led to the FDA’s Breakthrough Therapy Designation of felzartamab in October 2024,” reads a release from iMDx.

Market Reach and 2026 Goals

The company is currently engaged with 37 centers in the US and 11 internationally through research-use-only assays and registry studies. These US centers represent more than 25% of all transplants performed annually in the country.

The iMDx leadership team notes that 2026 represents a transition from a product development-stage company into a commercialization-stage company. In addition to seeking FDA authorization, the company’s goals for the year include expanding its registry trial to 28 sites and generating further peer-reviewed publications regarding the CM-score and absolute quantification.

The assay’s analytical sensitivity at low levels and its low relative change value are also cited as critical factors for longitudinal recurrence monitoring. These features may allow clinicians to identify meaningful trends before the onset of graft deterioration.

ID 449492720 © Jittawit Tachakanjanapong | Dreamstime.com

Related Articles: