Natera launches Prospera with quantification to improve kidney graft rejection testing

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Natera has announced the launch of Prospera with quantification, the only cell-free DNA (cfDNA) test for kidney rejection that provides three values—the quantity of donor-derived cfDNA (dd-cfDNA), fraction of dd-cfDNA, and total cfDNA—on every report. Combining these three metrics has been shown to improve sensitivity when evaluating transplant rejection, compared to using dd-cfDNA fraction alone, according to a Natera press release.

Currently, other commercially available cfDNA tests that assess transplant rejection only report the fraction of dd-cfDNA, the release adds.

A recent peer-reviewed paper published in the Journal of the American Society of Nephrology (JASN) showcased improved performance from Prospera with quantification in 41 kidney transplant patients, 9 of whom had rejection. Incorporating the quantity of dd-cfDNA with the fraction of dd-cfDNA improved the sensitivity of the Prospera test from 7/9 to 9/9 in cases of active rejection, which was then confirmed through renal biopsy.

“Total cfDNA is often elevated during viral infections and other complicated scenarios due to increases in the host-derived fraction,” said Suphamai Bunnapradist, transplant nephrologist at the University of California Los Angeles (UCLA) in Los Angeles, USA, and senior author of the JASN study. “Consequently, the percentage of dd-cfDNA can be artificially depressed in these scenarios, leading to false negative results. The absolute quantification of dd-cfDNA in the sample is a game-changer, as it makes the test more robust in challenging clinical scenarios while boosting its sensitivity.”

The Prospera test leverages Natera’s core single-nucleotide (SNP)-based, massively multiplexed PCR (mmPCR) technology to identify allograft rejection non-invasively, and with high precision and accuracy, without the need for prior donor or recipient genotyping. The test works by measuring the fraction of dd-cfDNA in the recipient’s blood. It may be used by physicians considering the diagnosis of active rejection, helping to rule in or out this condition when evaluating the need for diagnostic testing or the results of an invasive biopsy.

The Prospera test has been clinically and analytically validated for performance regardless of donor relatedness, rejection type, and clinical presentation. It has been developed and its performance characteristics determined by Natera, the CLIA-certified laboratory performing the test, but is yet to gain US Food and Drug Administration (FDA) clearance.

Its clinical utility and increase in sensitivity have now been seen in six independent datasets, including in the large international, multicentre, prospective Trifecta study, which is expected to be published in early 2022.

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