Recent Patents on Biomarkers (Discontinued) - Volume 2, Issue 3, 2012

Acute kidney injury (AKI), a syndrome that is defined by a sudden and substantial decrease in kidney function, can be caused by a variety of mechanisms including circulatory collapse, ischemia-reperfusion injury, systemic inflammatory response, endogenous or exogenous toxicants or urinary obstruction. The causal and temporal sequence of kidney injury leading to reduced function and in turn causing an increment in serum creatinine, however, hinders a timely detection of this syndrome and may therefore also delay its early and effective treatment. In recent years, an increasing number of promising biomarker candidates were described and patented to help in the detection, prognostic stratification and treatment of AKI. The discovery and evaluation of novel biomarkers for AKI holds the promise to improve early detection and allow for the development of effective treatments for this condition. This narrative review summarizes recent developments in AKI biomarker patenting with a focus on both diagnosis and treatment-oriented patents and patent applications. In addition, alternative methods for early detection of AKI, particularly patents and patent applications on continuous urine output- and glomerular filtration rate monitoring, are presented and discussed in comparison. Finally, important potential limitations for the application of biomarkers for AKI as well as alternative techniques for the measurement of kidney function are discussed.

Extensive pre-clinical studies have established the biological role, plausibility, and proof of concept of neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker for acute kidney injury (AKI). In AKI, there is a rapid and massive upregulation of NGAL in the kidney. The biological role of NGAL induction is attenuation of apoptosis and an enhanced proliferative response, as well as defense of the urinary system from bacteria. These actions are mediated by chelation of siderophores, removal of iron from extracellular environments and redirection to intracellular sites. In AKI, both urine and plasma NGAL are derived largely from the damaged nephron. NGAL expression in the kidney, urine, and plasma is directly proportional to the duration and severity of kidney injury, temporally correlated with the inciting stimulus, and specific to intrinsic AKI. These findings have now been successfully translated to multiple human studies, and NGAL has emerged as an excellent biomarker in the urine and plasma for early diagnosis, risk stratification, severity prediction, differential diagnosis, and outcomes prediction in several common clinical AKI scenarios. The deployment of standardized clinical platforms has further facilitated the validation of urine and plasma NGAL as an AKI biomarker. Some relevant patents are also summarized in this review.

Kidney Injury Molecule-1 (KIM-1 in humans, Kim-1 in rodents) was first reported in 1998 as a highly up regulated protein in rat ischemic kidneys, and was subsequently demonstrated as a urinary biomarker in 2002 by our laboratory. KIM-1 expression is absent in healthy kidney epithelium, but is markedly upregulated with tubular injury or dedifferentiation providing a high signal-to-noise ratio for accurate detection of kidney injury. Since its discovery, KIM-1 has evolved as a diagnostic, prognostic and predictive biomarker of various kidney diseases. Based on results from our laboratory and other research groups including large consortia, Federal Drug Administration (FDA), European Medicines Agency (EMA), and the Japanese Pharmaceuticals and Medical Devices Agency (PMDA) have qualified KIM-1 as a marker to monitor kidney injury in preclinical studies and on a case-by-case basis in clinical trials. Recent studies also highlight the therapeutic aspects of anti-KIM-1 agents in mitigating renal injury. We also discussed a selected number of recent patents on KIM-1 pertaining to kidney pathophysiology.

BUN and serum creatinine are not very sensitive and specific markers for the diagnosis of AKI as they are influenced by many renal and non-renal factors independent of kidney function. IL-18 is released into the urine by the injured kidney, analogous to the troponin release by injured myocardial cells after myocardial infarction, and is a more sensitive and specific early marker of AKI than BUN and serum creatinine. The most recent data on urine IL-18 comes from the Translational Research Investigating Biomarker Endpoints for Acute Kidney Injury (TRIBE-AKI) study. In 311 children and 1219 adults, urine IL-18 was increased in the first 6 hours after cardiac surgery in AKI patients that later developed a doubling of serum creatinine or the need for dialysis. In 2006, a patent was issued to inventors Charles L. Edelstein and Chirag R. Parikh entitled “Methods for detection of IL-18 as an early marker for the diagnosis of acute renal failure and predictor of mortality”. In addition to IL-18, patents have been issued for neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), Netrin-1, Gro-alpha (also known as CXCL1), heat shock protein-72, mannose- binding lectin (MBL), urinary cytokines and chemokines, aprotinin, and microalbumin as early diagnostic biomarkers of AKI. Also, there is a patent application for using proteomics for the discovery of biomarkers for the early detection of renal disease.

Acute kidney injury (AKI) is a common problem in the hospital setting and intensive care unit. Despite improved understanding, there are no effective therapies available to treat AKI. AKI is often diagnosed late and, therefore, identification of a biomarker that will facilitate early diagnosis of AKI and provide a prognosis is desirable. The recent identification of a novel biomarker, netrin-1, that is capable of diagnosing early during the course of kidney injury has created much interest in this molecule. In this paper, we review recent progress made in understanding netrin-1 as a biomarker and therapeutic molecule for acute and chronic kidney diseases. We also discuss both the usefulness of netrin-1 as a biomarker of other diseases and as a possible therapeutic agent and relevant patents for inflammatory diseases.

Acute Kidney Injury (AKI) remains a vexing clinical problem resulting in unacceptably high patient mortality, development of chronic kidney disease and accelerated progression to end stage kidney disease. Although clinical risks factors for developing AKI have been identified, there is no reasonable surveillance technique (“biomarker”) to definitively and rapidly diagnose and determine the extent of severity of AKI in any patient. Since patient outcomes correlate with the extent of injury, and effective therapy requires early intervention, the ability to rapidly diagnose and stratify patients by their level of kidney injury is paramount for clinical progress in this field. Therefore, FAST BioMedical is developing and characterizing an optical measurement technique utilizing a novel minimally invasive Ratiometric Fluorescence Device (RFD) that can rapidly, accurately, and repetitively quantify kidney function, the measured glomerular filtration rate (mGFR), independent of serum or urinary measurements. A sub-millimeter optical fiber, that delivers excitation light and collects fluorescent emissions, is inserted into a peripheral or central venous access via commercial intravenous catheters. A mixture of two fluorescent dextrans of different sizes and distinct fluorophores, a small freely kidney filterable “reporter” molecule and large non-filterable plasma volume “marker” molecules, is infused as a bolus, excited sequentially by light-emitting diodes, and in vivo signals detected and quantified by photomultiplier tubes. The patented quantitative ratiometric technique, by utilizing two fluorescent reporter molecules, minimizes the inherent limitations of intensity fluorescence determinations and allows for rapid and accurate determinations of mGFR and plasma volume. Utilization of plasma fluorescent detection allows for the use of a two compartment model thus markedly minimizing the time needed for measuring GFR by eliminating extracellular space distribution of the filterable molecule.

The development of minimally invasive tests for the detection and monitoring of cancers could greatly reduce the worldwide health burden of cancer. Recent discovery of a new class of small (22mer) non-coding RNA (miRNAs) opened up new perspectives in biomarker research. Since miRNA are directly involved in the regulation of almost all key cellular processes, including development, differentiation, proliferation, cell death and metabolism, they may prove to be powerful cancer biomarkers. Unlike other types of biomarkers, miRNAs in the circulation are protected within lipoprotein vesicles and thus are remarkably stable, making them robust and reliable biomarkers of cancer. In this review, we provide an overview on circulating miRNAs and their great potential as highly specific and sensitive biomarkers for tumor classification and prognostication. We discuss exosomal origin of the circulating miRNAs and additionally, address some recent findings in the new and upcoming area of exosomal miRNAs from cell culture supernatant and their potential in biomarkers discovery. We also review a selected number of recent patents relevant to the area of exosomal miRNAs relevant to biomarker discovery.

Several patents were published for HCV p7 protein including a synthetic p7 model for drug design and screening of experimental compounds. Additionally, patents were published for identification and use of compounds as p7 inhibitors. HCV p7 protein is a viral ion channel (viroporin) that was found to be crucial for viral production through facilitating assembly and release. Accordingly, targeting the protein is expected to inhibit these stages in the HCV lifecycle. p7 inhibitors displayed effectiveness against recombinant replicons of different HCV genotypes with genotype-dependant responses, but they were never tested on genotype 4 (GT-4). Our study focused on examining the effects of four p7 inhibitors; amantadine, rimantadine, N-nonyl-deoxynojirimycin (NN-DNJ) and hexamethylene amiloride (HMA) on HCV GT-4 for the first time which involves the majority of cases in Egypt and the Middle East-North Africa (MENA) region. HCV viral load was assessed after stimulation by p7 inhibitors for HCV-positive Peripheral Blood Mononuclear Cells (PBMCs) which are known to be extra-hepatic reservoirs for the virus. The compounds showed strong reduction of viral load without affecting cell viability in congruency with previous experimental work that alternatively used other HCV genotypes and cell lines.

The recent patents annotated in this section have been selected from various patent databases, and are relevant to the articles published in this journal issue. The patents are categorized in fast emerging patent biomarker applications e.g. discovery and validation in drug discovery, clinical development and molecular diagnostics, bioinformatics, preclinical biomarker discovery, personalized medicine, translational biomarkers and therapeutic interventions.......