NEW YORK(GenomeWeb) – A study sponsored by Astute Medical has found that the company's NephroCheck test for acute kidney injury is also predictive of adverse long term outcomes in AKI patients.
While Astute has no current plans to position NephroCheck as a tool for long-term prognosis and the test is not cleared in the US for such a use, the findings bolster the data supporting use of the test in the acute setting, Astute CSO Paul McPherson told GenomeWeb. He added that the data also suggests the test could be useful for selecting patient cohorts for clinical trials looking at therapies to combat long-term kidney injury.
Detailed in a paper published last month in the Journal of the American Society of Nephrology, the study followed 692 ICU patients for nine months, looking at the extent to which NephroCheck – which measures the presence of two proteins, insulin-like growth-factor binding protein 7 (IGFBP7) and tissue inhibitor of metalloproteinases (TIMP-2), in urine – could predict patients who would either die or go on dialysis during this time period.
Of the initial 692 subjects, at least three months of follow-up were available for 639 and the full nine months of follow-up were available for 552. In all, 217 met the primary endpoints of either death or dialysis.
Looking at the ICU patients with the two predefined cutoffs used in NephroCheck testing for AKI – a low cutoff of 0.3 aimed at maximizing sensitivity and a high cutoff of 2.0 aimed at maximizing specificity – the researchers found that AKI patients with NephroCheck scores of 2.0 and above had roughly double the risk of proceeding to either death or dialysis within the next nine months compared to AKI patients with scores at or below the 0.3 cutoff.
"The higher the [protein marker] concentration, the more likely you are to have short-term [AKI] events and also long-term complications," John Kellum, professor of Critical Care Medicine at the University of Pittsburgh and senior author on the study, told GenomeWeb.
This, he noted, bolsters the case that the test is measuring "something biologically real" related to AKI.
The research was part of a larger 744-patient multi-center study looking at the performance of NephroCheck in predicting AKI – the use for which it is marketed and cleared by the US Food and Drug Administration.
Astute published results from that study related to the test's performance in identifying patients at risk of AKI in 2013 in the journal Critical Care. Given the nine-month follow up time, data from the long-term portion of the study was later in coming, McPherson said, but, he noted, it was part of the company's plan from the beginning.
He cited the example of troponin and the fact that, while that marker has not been widely used for long-term prognosis of cardiac events, demonstrating its link to long-term events was key to building support for its use in an acute setting.
"Those data and publications [on long-term outcomes] were important to its adoption," McPherson said. "So knowing that history led us to plan this analysis from the start."
The relationship of the test to long-term outcomes "is an essential question that people asked very early on," said Astute CEO Christopher Hibberd. "So we started with the goal of collecting this information, because people wanted to know what the linkage is."
Hibberd added that while the JASN study was not intended to demonstrate NephroCheck's utility as a long-term prognostic, the company is researching and developing a number of additional tests for various aspects of kidney injury, including long-term prognosis.
Kellum noted as well that the data indicates the test could be useful in selecting patients for clinical trial cohorts. Ideally, he said, drugmakers would want to enroll AKI patients who in the long term would go on to either die or develop complications without therapeutic intervention, and the test could help them identify this population. McPherson said the company has received inquiries from parties interested in using the test for this purpose.
Astute received FDA 510(k) clearance in September for NephroCheck as a tool for identifying patients at risk of AKI. The test is intended for use in ICU patients suffering from acute cardiovascular or respiratory conditions and has been shown to predict their risk of suffering AKI within the next 12 hours with an accuracy of around 90 percent.
Astute launched the test in December, offering it through its partner Ortho-Clinical Diagnostics. with which it signed a strategic collaboration agreement in August. Under that agreement, in exchange for a $15 million equity investment from OCD, Astute made the company the exclusive sales agent for NephroCheck and the Astute 140 Meter device on which the test is performed. Astute also granted OCD a semi-exclusive global license to develop and commercialize a version of NephroCheck for use on OCD's Vitros line of automated testing platforms.
Hibberd said this week that an automated version of the test on the OCD platform was currently under development and "moving along nicely."