A New Biomarker for AIN?
Meanwhile, research is also moving forward on a better biomarker for AIN, which is also under the AKI umbrella.
“It’s important to diagnose AIN because it has a very specific treatment,” Dennis G. Moledina, MD, PhD, Yale School of Medicine in New Haven, Connecticut, told this news organization.
“AIN is caused by a bunch of different medications, such as proton pump inhibitors, cancer drugs, nonsteroidal anti-inflammatory drugs, and antibiotics, so when someone has this condition, you have to stop potentially life-saving medications and give unnecessary and potentially toxic immunosuppressive drugs, like prednisone,” he said. “If you get the diagnosis wrong, you’re stopping vital drugs and giving immunosuppression for no reason. And if you miss the diagnosis, AIN can lead to permanent chronic kidney disease.”
“Right now, the only way to diagnose AIN is to do a kidney biopsy, which is risky because it can often lead to significant bleeding,” he said. “Some people can’t undergo a biopsy because they’re on medications that increase the risk of bleeding, and they can’t be stopped.”
Furthermore, he noted, “the longer a patient takes a drug that’s causing AIN without getting a diagnosis, the less the chances of recovery because the longer you let this kidney inflammation go on, the more fibrosis and permanent damage develops. So it is important to diagnose it as early as possible, and that’s again why we have a real need for a noninvasive biomarker that can be tested rapidly.”
Moledina and colleagues have been working on identifying a suitable biomarker for close to 10 years, the latest example of which is their 2023 study validating urinary CXCL9 as just such a marker.
“We’re most excited about CXCL9 because it’s already used to diagnose some other diseases in plasma,” Moledina said. “We think that we can convince labs to test it in urine.”
In an accompanying editorial, Mark Canney, PhD, and colleagues at the University of Ottawa and The Ottawa Hospital in Ontario, Canada, wrote that the CXCL9 study findings “are exciting because they provide a road map of where diagnostics can get to for this common, yet poorly identified and treated, cause of kidney damage. The need for a different approach can be readily identified from the fact that clinicians’ gestalt for diagnosing AIN was almost tantamount to tossing a coin (AUC, 0.57). CXCL9 alone outperformed not only the clinician’s prebiopsy suspicion but also an existing diagnostic model and other candidate biomarkers both in the discovery and external validation cohorts.”
Like NGAL, CXCL9 will have to go through the FDA approval process before it can be used for AIN. Therefore, it may be a few years before it can become routinely available, Moledina said.
Nevertheless, Nerenz added, “I think the next steps for AKI are probably continuing on this path of context-dependent, selective biomarker use. I anticipate that we’ll see ongoing development in this space, just expanding to a wider variety of clinical scenarios.”
Nerenz declared receiving research funding from Abbott Labs for evaluation of an AKI biomarker. Moledina is a co-inventor on a pending patent, “Methods and Systems for Diagnosis of Acute Interstitial Nephritis”; a cofounder of the diagnostics company Predict AIN; and a consultant for Biohaven.
A version of this article first appeared on Medscape.com.