Quantification of Serum High Mobility Group Box 1 by Liquid Chromatography/High-Resolution Mass Spectrometry: Implications for Its Role in Immunity, Inflammation, and Cancer

Ferroptosis and HMGB2 induced calreticulin translocation required for immunogenic cell death are controlled by the nuclear exporter XPO1

Cisplatin and oxaliplatin cause the secretion of high mobility group box 1 (HMGB1) from cancer cells, which is necessary for initiation of immunogenic cell death (ICD). Calreticulin (CRT) translocation from the endoplasmic reticulum to the plasma membrane is also required; oxaliplatin induces this translocation but cisplatin does not. We have discovered that oxaliplatin causes the secretion of both HMGB1 and HMGB2 from the nucleus into the extracellular milieu. We previously showed that cisplatin mediated secretion of HMGB1 is controlled by the nuclear exporter XPO1 (chromosomal maintenance 1; CRM1). We now find that XPO1 regulates oxaliplatin mediated secretion of both HMGB1 and HMGB2. XPO1 inhibition causes nuclear accumulation of both proteins, inhibition of oxaliplatin-mediated ferroptosis of colon cancer cells, and inhibition of CRT translocation to the plasma membrane of lung and colon cancer cells. Incubation of cancer cells with cell targeted (CT)-HMGB2 confirmed that HMGB2 is responsible for translocation of CRT to the plasma membrane. CT-HMGB2 is three orders of magnitude more potent than oxaliplatin at inducing CRT translocation. Inhibition of HMGB1 and HMGB2 secretion and/or their activation of nuclear factor-kappa B (NF-kB) has potential utility for treating cardiovascular, and neurodegenerative diseases; whereas CT-HMGB2 could augment therapeutic approaches to cancer treatment.

Quantification of human mature frataxin protein expression in nonhuman primate hearts after gene therapy

Deficiency in human mature frataxin (hFXN-M) protein is responsible for the devastating neurodegenerative and cardiodegenerative disease of Friedreich's ataxia (FRDA). It results primarily through epigenetic silencing of the FXN gene by GAA triplet repeats on intron 1 of both alleles. GAA repeat lengths are most commonly between 600 and 1200 but can reach 1700. A subset of approximately 3% of FRDA patients have GAA repeats on one allele and a mutation on the other. FRDA patients die most commonly in their 30s from heart disease. Therefore, increasing expression of heart hFXN-M using gene therapy offers a way to prevent early mortality in FRDA. We used rhesus macaque monkeys to test the pharmacology of an adeno-associated virus (AAV)hu68.CB7.hFXN therapy. The advantage of using non-human primates for hFXN-M gene therapy studies is that hFXN-M and monkey FXN-M (mFXN-M) are 98.5% identical, which limits potential immunologic side-effects. However, this presented a formidable bioanalytical challenge in quantification of proteins with almost identical sequences. This could be overcome by the development of a species-specific quantitative mass spectrometry-based method, which has revealed for the first time, robust transgene-specific human protein expression in monkey heart tissue. The dose response is non-linear resulting in a ten-fold increase in monkey heart hFXN-M protein expression with only a three-fold increase in dose of the vector.

Targeting HMGB1: A Potential Therapeutic Strategy for Chronic Kidney Disease

High-mobility group protein box 1 (HMGB1) is a member of a highly conserved high-mobility group protein present in all cell types. HMGB1 plays multiple roles both inside and outside the cell, depending on its subcellular localization, context, and post-translational modifications. HMGB1 is also associated with the progression of various diseases. Particularly, HMGB1 plays a critical role in CKD progression and prognosis. HMGB1 participates in multiple key events in CKD progression by activating downstream signals, including renal inflammation, the onset of persistent fibrosis, renal aging, AKI-to-CKD transition, and important cardiovascular complications. More importantly, HMGB1 plays a distinct role in the chronic pathophysiology of kidney disease, which differs from that in acute lesions. This review describes the regulatory role of HMGB1 in renal homeostasis and summarizes how HMGB1 affects CKD progression and prognosis. Finally, some promising therapeutic strategies for the targeted inhibition of HMGB1 in improving CKD are summarized. Although the application of HMGB1 as a therapeutic target in CKD faces some challenges, a more in-depth understanding of the intracellular and extracellular regulatory mechanisms of HMGB1 that underly the occurrence and progression of CKD might render HMGB1 an attractive therapeutic target for CKD.

Cisplatin Dependent Secretion of Immunomodulatory High Mobility Group Box 1 (HMGB1) Protein from Lung Cancer Cells

High mobility group box 1 (HMGB1) is secreted from activated immune cells, necrotic cells, and certain cancers. Previous studies have reported that different patterns of post-translational modification, particularly acetylation and oxidation, mediate HMGB1 release and confer distinct extracellular HMGB1 signaling activity. Here we report that cisplatin but not carboplatin induces secretion of HMGB1 from human A549 non-small cell lung cancer (NSCLC) cells. Cisplatin-mediated HMGB1 secretion was dose-dependent and was regulated by nuclear exportin 1 (XPO1) also known as chromosomal maintenance 1 (CRM1) rather than adenosine diphosphate (ADP)-ribosylation, acetylation, or oxidation. HMGB1, as well as lysine acetylation and cysteine disulfide oxidation of secreted HMGB1, were monitored by sensitive and specific assays using immunoprecipitation, stable isotope dilution, differential alkylation, and nano liquid chromatography parallel reaction monitoring/high-resolution mass spectrometry (nano-LC-PRM/HRMS). A major fraction of the HMGB1 secreted by low-dose cisplatin treatment of A549 NSCLC cells was found to be in the fully reduced form. In contrast, mainly oxidized forms of HMGB1 were secreted by dimethyl sulfoxide (DMSO)-mediated apoptosis. These findings suggest that inhibition of XPO1 could potentiate the anti-tumor activity of cisplatin by increasing the nuclear accumulation of HMGB1 protein, an inhibitor of cisplatin DNA-adduct repair. Furthermore, low-dose cisplatin therapy could modulate the immune response in NSCLC through the established chemokine activity of extracellular reduced HMGB1. This could potentially enhance the efficacy of subsequent immunotherapy treatment.

The androgen receptor

The Androgen Receptor (AR) is a ligand (androgen) activated transcription factor and a member of the nuclear receptor (NR) superfamily. It is required for male sex hormone function. AR-FL (full-length) has the domain structure of NRs, an N-terminal domain (NTD) required for transactivation, a DNA-binding domain (DBD), a nuclear localization signal (NLS) and a ligand-binding domain (LBD). Paradoxes exist in that endogenous ligands testosterone (T) and 5α-dihydrotestosterone (DHT) have differential effects on male sexual development while binding to the same receptor and transcriptional specificity is achieved even though the androgen response elements (AREs) are identical to those seen for the progesterone, glucocorticoid and mineralocorticoid receptors. A high resolution 3-dimensional structure of AR-FL by either cryo-EM or X-ray crystallography has remained elusive largely due to the intrinsic disorder of the NTD. AR function is regulated by post-translational modification leading to a large number of proteoforms. The interaction of these proteoforms in multiprotein complexes with co-activators and co-repressors driven by interdomain coupling mediates the AR transcriptional output. The AR is a drug target for selective androgen receptor modulators (SARMS) that either have anabolic or androgenic effects. Protstate cancer is treated with androgen deprivation therapy or by the use of AR antagonists that bind to the LBD. Drug resistance occurs due to adaptive AR upregulation and the appearance of splice variants that lack the LBD and become constitutively active. Bipolar T treatment and NTD-antagonists could surmount these resistance mechanisms, respectively. These recent advances in AR signaling are described.

Quantification of human mature frataxin protein expression in nonhuman primate hearts after gene therapy

Deficiency in human mature frataxin (hFXN-M) protein is responsible for the devastating neurodegenerative and cardiodegenerative disease of Friedreich's ataxia (FRDA). It results primarily by epigenetic silencing the FXN gene due to up to 1400 GAA triplet repeats in intron 1 of both alleles of the gene; a subset of approximately 3% of FRDA patients have a mutation on one allele. FRDA patients die most commonly in their 30s from heart disease. Therefore, increasing expression of heart hFXN-M using gene therapy offers a way to prevent early mortality in FRDA. We used rhesus macaque monkeys to test the pharmacology of an adeno-associated virus (AAV)hu68.CB7.hFXN therapy. The advantage of using non-human primates for hFXN-M gene therapy studies is that hFXN-M and monkey FXN-M (mFXN-M) are 98.5% identical, which limits potential immunologic side-effects. However, this presented a formidable bioanalytical challenge in quantification of proteins with almost identical sequences. This was overcome by development of a species-specific quantitative mass spectrometry-based method, which revealed for the first time, robust transgene-specific human protein expression in monkey heart tissue. The dose response was non-linear resulting in a ten-fold increase in monkey heart hFXN-M protein expression with only a three-fold increase in dose of the vector.

Liquid Chromatography-Mass Spectrometry Analysis of Frataxin Proteoforms in Whole Blood as Biomarkers of the Genetic Disease Friedreich's Ataxia

Friedreich's ataxia (FRDA) is caused primarily by expanded GAA repeats in intron 1 of both alleles of the FXN gene, which causes transcriptional silencing and reduced expression of frataxin mRNA and protein. FRDA is characterized by slowly progressive ataxia and cardiomyopathy. Symptoms generally appear during adolescence, and patients slowly progress to wheelchair dependency usually in the late teens or early twenties with death on average in the 4th decade. There are two known mature proteoforms of frataxin. Mitochondrial frataxin (frataxin-M) is a 130-amino acid protein with a molecular weight of 14,268 Da, and there is an alternatively spliced N-terminally acetylated 135-amino acid form (frataxin-E) with a molecular weight of 14,953 Da found in erythrocytes. There is reduced expression of frataxin in the heart and brain, but frataxin is not secreted into the systemic circulation, so it cannot be analyzed in serum or plasma. Blood is a readily accessible biofluid that contains numerous different cell types that express frataxin. We have found that pig blood can serve as an excellent surrogate matrix to validate an assay for frataxin proteoforms because pig frataxin is lost during the immunoprecipitation step used to isolate human frataxin. Frataxin-M is expressed in blood cells that contain mitochondria, whereas extra-mitochondrial frataxin-E is found in erythrocytes. This means that the analysis of frataxin in whole blood provides information on the concentration of both proteoforms without having to isolate the individual cell types. In the current study, we observed that the distributions of frataxin levels for a sample of 25 healthy controls and 50 FRDA patients were completely separated from each other, suggesting 100% specificity and 100% sensitivity for distinguishing healthy controls from FRDA cases, a very unusual finding for a biomarker assay. Additionally, frataxin levels were significantly correlated with the GAA repeat length and age of onset with higher correlations for extra-mitochondrial frataxin-E than those for mitochondrial frataxin-M. These findings auger well for using frataxin levels measured by the validated stable isotope dilution ultrahigh-performance liquid chromatography-multiple reaction monitoring/mass spectrometry assay to monitor therapeutic interventions and the natural history of FRDA. Our study also illustrates the utility of using whole blood for protein disease biomarker discovery and validation.

Parallel-reaction monitoring revealed altered expression of a number of epitranscriptomic reader, writer, and eraser proteins accompanied with colorectal cancer metastasis

RNA contains more than 170 types of chemical modifications, and these modified nucleosides are recognized, installed and removed by their reader, writer, and eraser (RWE) proteins, respectively. Here, we employed a parallel-reaction monitoring (PRM)-based targeted proteomic method, in conjunction with stable isotope labeling by amino acids in cell culture (SILAC), to examine comprehensively the differential expression of epitranscriptomic RWE proteins in a matched pair of primary/metastatic colorectal cancer (CRC) cells, namely SW480/SW620. We were able to quantify 113 nonredundant epitranscriptomic RWE proteins; among them, 48 and 5 were up- and down-regulated by >1.5-fold in SW620 over SW480 cells, respectively. Some of those proteins with marked up-regulation in metastatic CRC cells, including NAT10, hnRNPC, and DKC1, were documented to assume important roles in the metastasis of CRC and other types of cancer. Interrogation of the Clinical Proteomic Tumor Analysis Consortium data revealed the involvement of DUS1L in the initiation and metastatic transformation of CRC. It can be envisaged that the PRM method can be utilized, in the future, to identify epitranscriptomic RWE proteins involved in the metastatic transformations of other types of cancer.

Reappraisal of oxidized HMGB1 as a mediator and biomarker

HMGB1 is a dual-function protein that acts as a chromatin-binding protein and as a danger-associated molecular pattern (DAMP) when released from activated immune cells or injured tissue. In much of the HMGB1 literature, immunomodulatory effects of extracellular HMGB1 are proposed to depend on its oxidation state. However, many of the foundational studies for this model have been retracted or flagged with expressions of concern. The literature on HMGB1 oxidation reveals a diversity of redox proteoforms of HMGB1 that are inconsistent with current models of redox modulation regulating HMGB1 secretion. A recent study of acetaminophen toxicity has identified previously unrecognized HMGB1 oxidized proteoforms. HMGB1 undergoes oxidative modifications that could serve as pathology-specific biomarkers and drug targets.

Characterization and Quantification of Oxidized High Mobility Group Box 1 Proteoforms Secreted from Hepatocytes by Toxic Levels of Acetaminophen

The high mobility group box 1 (HMGB1), which is released during acute acetaminophen (APAP) overdose, is thought to mediate a subsequent immune response, particularly hepatic infiltration of macrophages. The redox behavior of HMGB1 and the proteoforms of HMGB1 present in oxidative environments has been the subject of a number of confusing and contradictory studies. Therefore, a stable isotope dilution two-dimensional nanoultrahigh-performance liquid chromatography parallel reaction monitoring/high-resolution mass spectrometry method was developed in order to characterize and quantify oxidative modifications to the cysteine (Cys) residues (Cys-23, Cys-45, and Cys-106) that are present in HMGB1. Disulfide linkages were determined using carbamidoethyl derivatization before and after reduction as well as by direct analysis of disulfide cross-linked peptides. A stable isotope labeled form of HMGB1 was used as an internal standard to correct for sample to sample differences in immunoaffinity precipitation, derivatization, and electrospray ionization. Four discrete HMGB1 proteoforms were found to be released from a hepatocarcinoma cell model of APAP overdose after 24 h. Fully reduced HMGB1 with all three Cys-residues in their free thiol state accounted for 18% of the secreted HMGB1. The proteoform with disulfide between Cys-23 and Cys-45 accounted for 24% of the HMGB1. No evidence was obtained for a disulfide cross-link between Cys-106 and the other two Cys-residues. However, 45% of the HMGB1 formed a cross-link with unidentified intracellular proteins via an intermolecular disulfide bond, and 12% was present as the terminally oxidized cysteic acid. Surprisingly, there was no evidence for the formation of HMGB1 disulfides with GSH or other low molecular weight thiols. Secreted plasma HMGB1 Cys-23/Cys45 disulfide proteoform together with the Cys-106/protein disulfide proteoforms could potentially serve as early biomarkers of hepatoxicity after APAP overdose as well as biomarkers of drug-induced liver injury.

Progress in Assays of HMGB1 Levels in Human Plasma—The Potential Prognostic Value in COVID-19

Extracellular HMGB1 protein is known to induce inflammatory responses leading to an inflammatory storm. The outbreak of the Severe Acute Respiratory Syndrome COVID-19 due to the SARS-CoV-2 virus has resulted in a huge health concern worldwide. Recent data revealed that plasma/serum HMGB1 levels of patients suffering from inflammation-mediated disorders—such as COVID-19, cancer, and autoimmune disorders—correlate positively with disease severity and vice versa. A late release of HMGB1 in sepsis suggests the existence of a wide therapeutic window for treating sepsis. Rapid and accurate methods for the detection of HMGB1 levels in plasma/serum are, therefore, of great importance for monitoring the occurrence, treatment success, and survival prediction of patients with inflammation-mediated diseases. In this review, we briefly explain the role of HMGB1 in the cell, and particularly the involvement of extracellular HMGB1 (released from the cells) in inflammation-mediated diseases, with an emphasis on COVID-19. The current assays to measure HMGB1 levels in human plasma—Western blotting, ELISA, EMSA, and a new approach based on electrochemical immunosensors, including some of our preliminary results—are presented and thoroughly discussed.

Matrix and Sampling Effects on Quantification of Protein Biomarkers of Drug-Induced Liver Injury

Macrophage colony stimulating factor 1 receptor (MCSF1R), osteopontin (OPN), high-mobility group protein B1 (HMGB1), glutamate dehydrogenase (GLDH), keratin 18 (K18), and caspase-cleaved keratin 18 (ccK18) are considered promising mechanistic biomarkers for the diagnosis of drug-induced liver injury. Here, we aim to elucidate the impact of the sample matrix and handling on the quantification of these emerging protein biomarkers. We investigated effects such as time from collection to centrifugation during serum (± gel) or EDTA plasma preparation on two assay platforms: immunoaffinity liquid chromatography mass spectrometric assays and sandwich immunoassays. Furthermore, we measured GLDH activity with an enzymatic activity assay. Matrix effects were observed particularly for HMGB1 and MCSF1R. HMGB1 levels were higher in serum than in plasma, whereas higher concentrations of MCSF1R were observed in plasma than in serum. A comparison of sample collection to centrifugation time ranging from 15 to 60 min demonstrated increasing levels of HMGB1 in serum, while MCSF1R, OPN, GLDH, and ccK18 concentrations remained stable. Additionally, there was a poor correlation in HMGB1 and ccK18 levels between serum and plasma. Considering the observed matrix effects, we recommend plasma as a matrix of choice and cross-study comparison studies to be limited to those using the same matrix.

Sample Preparation Strategies for Antibody-Free Quantitative Analysis of High Mobility Group Box 1 Protein

Sickness behavior and fatigue are induced by cerebral mechanisms involving inflammatory cytokines. High mobility group box 1 (HMGB1) is an alarmin, and a potential key player in this process. Reliable quantification methods for total HMGB1 and its redox variants must be established in order to clearly understand how it functions. Current methods pose significant challenges due to interference from other plasma proteins and autoantibodies. We aimed to develop an antibody-free sample preparation method followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to measure HMGB1 in human plasma. Different methods were applied for the removal of interfering proteins and the enrichment of HMGB1 from spiked human plasma samples. A comparison of methods showed an overall low extraction recovery (<40%), probably due to the stickiness of HMGB1. Reversed-phase liquid chromatography separation of intact proteins in diluted plasma yielded the most promising results. The method produced an even higher degree of HMGB1 purification than that observed with immunoaffinity extraction. Detection sensitivity needs to be further improved for the measurement of HMGB1 in patient samples. Nevertheless, it has been demonstrated that a versatile and fully antibody-free sample preparation method is possible, which could be of great use in further investigations.

Using biochemistry and biophysics to extinguish androgen receptor signaling in prostate cancer

Castration resistant prostate cancer (CRPC) continues to be androgen receptor (AR) driven. Inhibition of AR signaling in CRPC could be advanced using state-of-the-art biophysical and biochemical techniques. Structural characterization of AR and its complexes by cryo-electron microscopy would advance the development of N-terminal domain (NTD) and ligand-binding domain (LBD) antagonists. The structural basis of AR function is unlikely to be determined by any single structure due to the intrinsic disorder of its NTD, which not only interacts with coregulators but likely accounts for the constitutive activity of AR-splice variants (SV), which lack the LBD and emerge in CRPC. Using different AR constructs lacking the LBD, their effects on protein folding, DNA binding, and transcriptional activity could reveal how interdomain coupling explains the activity of AR-SVs. The AR also interacts with coregulators that promote chromatin looping. Elucidating the mechanisms involved can identify vulnerabilities to treat CRPC, which do not involve targeting the AR. Phosphorylation of the AR coactivator MED-1 by CDK7 is one mechanism that can be blocked by the use of CDK7 inhibitors. CRPC gains resistance to AR signaling inhibitors (ARSI). Drug resistance may involve AR-SVs, but their role requires their reliable quantification by SILAC-mass spectrometry during disease progression. ARSI drug resistance also occurs by intratumoral androgen biosynthesis catalyzed by AKR1C3 (type 5 17β-hydroxysteroid dehydrogenase), which is unique in that its acts as a coactivator of AR. Novel bifunctional inhibitors that competitively inhibit AKR1C3 and block its coactivator function could be developed using reverse-micelle NMR and fragment-based drug discovery.

The proteome and its dynamics: A missing piece for integrative multi-omics in schizophrenia

The complex and heterogeneous pathophysiology of schizophrenia can be deconstructed by integration of large-scale datasets encompassing genes through behavioral phenotypes. Genome-wide datasets are now available for genetic, epigenetic and transcriptomic variations in schizophrenia, which are then analyzed by newly devised systems biology algorithms. A missing piece, however, is the inclusion of information on the proteome and its dynamics in schizophrenia. Proteomics has lagged behind omics of the genome, transcriptome and epigenome since analytic platforms were relatively less robust for proteins. There has been remarkable progress, however, in the instrumentation of liquid chromatography (LC) and mass spectrometry (MS) (LCMS), experimental paradigms and bioinformatics of the proteome. Here, we present a summary of methodological innovations of recent years in MS based proteomics and the power of new generation proteomics, review proteomics studies that have been conducted in schizophrenia to date, and propose how such data can be analyzed and integrated with other omics results. The function of a protein is determined by multiple molecular properties, i.e., subcellular localization, posttranslational modification (PTMs) and protein-protein interactions (PPIs). Incorporation of these properties poses additional challenges in proteomics and their integration with other omics; yet is a critical next step to close the loop of multi-omics integration. In sum, the recent advent of high-throughput proteome characterization technologies and novel mathematical approaches enable us to incorporate functional properties of the proteome to offer a comprehensive multi-omics based understanding of schizophrenia pathophysiology.

Protein Biomarker Quantification by Immunoaffinity Liquid Chromatography–Tandem Mass Spectrometry: Current State and Future Vision

Immunoaffinity–mass spectrometry (IA-MS) is an emerging analytical genre with several advantages for profiling and determination of protein biomarkers. Because IA-MS combines affinity capture, analogous to ligand binding assays (LBAs), with mass spectrometry (MS) detection, this platform is often described using the term hybrid methods. The purpose of this report is to provide an overview of the principles of IA-MS and to demonstrate, through application, the unique power and potential of this technology. By combining target immunoaffinity enrichment with the use of stable isotope-labeled internal standards and MS detection, IA-MS achieves high sensitivity while providing unparalleled specificity for the quantification of protein biomarkers in fluids and tissues. In recent years, significant uptake of IA-MS has occurred in the pharmaceutical industry, particularly in the early stages of clinical development, enabling biomarker measurement previously considered unattainable. By comparison, IA-MS adoption by CLIA laboratories has occurred more slowly. Current barriers to IA-MS use and opportunities for expanded adoption are discussed. The path forward involves identifying applications for which IA-MS is the best option compared with LBA or MS technologies alone. IA-MS will continue to benefit from advances in reagent generation, more sensitive and higher throughput MS technologies, and continued growth in use by the broader analytical community. Collectively, the pursuit of these opportunities will secure expanded long-term use of IA-MS for clinical applications.

Development of a method to screen and isolate bioactive constituents from Stellera chamaejasme by ultrafiltration and liquid chromatography combined with semi-preparative high-performance liquid chromatography and high-speed counter current chromatography

A simple and efficient method based on ultrafiltration with liquid chromatography and mass spectrometry was used for the rapid screening and identification of ligands in the extracts of Stellera chamaejasme. The bound ligands, i.e. daphnoretin, isopimpinellin, chamaechromone, neochamaejasmin A, and chamaejasmine (purity of 96.8, 90.75, 91.41, 93.98, and 98.91%, respectively), were separated by semi-preparative high-performance liquid chromatography combined with high-speed counter-current chromatography. To the best of our knowledge, this is the first study to report the detection of potent lipoxidase and lactate dehydrogenase inhibitors in Stellera chamaejasme extracts. The results demonstrate that our method of ultrafiltration with liquid chromatography and mass spectrometry combined with mixed chromatography can be used to screen and confirm the bioactivity of all isolated compounds. This method also eliminates the need for separation of inactive compounds, thereby improving efficiency when studying bioactive substances. For some complex mixtures, neither semi-preparative high-performance liquid chromatography nor high-speed counter-current chromatography can purify all the target active compounds with high purity in a one-step separation. The combination of the two methods allow for efficient purification of target bioactive compounds with different polarities and physicochemical properties based on their complementary properties.

The current state of biomarker research for Friedreich's ataxia: a report from the 2018 FARA biomarker meeting

The 2018 FARA Biomarker Meeting highlighted the current state of development of biomarkers for Friedreich’s ataxia. A mass spectroscopy assay to sensitively measure mature frataxin (reduction of which is the root cause of disease) is being developed. Biomarkers to monitor neurological disease progression include imaging, electrophysiological measures and measures of nerve function, which may be measured either in serum and/or through imaging-based technologies. Potential pharmacodynamic biomarkers include metabolic and protein biomarkers and markers of nerve damage. Cardiac imaging and serum biomarkers may reflect cardiac disease progression. Considerable progress has been made in the development of biomarkers for various contexts of use, but further work is needed in terms of larger longitudinal multisite studies, and identification of novel biomarkers for additional use cases

Biomarkers are characteristics that can be objectively measured, evaluated and used as indicators of disease progression or the effect of a therapy. Friedreich’s ataxia is a progressive multisystem neuromuscular disease with no treatment. Current clinical measures cannot robustly detect disease progression in less than a year, meaning that clinical trials are long and drug development is slow. The Friedreich’s Ataxia Research Alliance and the scientific community are looking for biomarkers that show change in shorter time frames that can accelerate drug development. The 2018 FARA Biomarker Meeting summarized the exciting findings that represent the current state of the field.