ABSTRACT Background In a recent Phase 2 trial in patients with cancer cachexia, the anti‐GDF‐15 antibody ponsegromab resulted in increased body weight, appetite, muscle mass and physical activity. This study provides compelling evidence that targeting the GDF‐15 pathway may offer a viable therapeutic strategy, while raising new mechanistic questions about how GDF‐15 neutralization could be optimally integrated with other interventions to reverse the multifactorial cachexia syndrome. This series of experiments aimed to evaluate the effects of anti‐GDF‐15 antibody treatment in combination with muscle anabolic (anti‐myostatin antibody) or appetite stimulant (ghrelin receptor agonist anamorelin) modulators using mouse cancer cachexia models. Methods The effects of anti‐GDF‐15 monoclonal antibody alone and in combination with an anti‐myostatin antibody or anamorelin fumarate were examined in GDF‐15‐dependent (HT‐1080 and RENCA) and partially dependent (TOV21G) mouse tumour models. Comprehensive assessments included food intake, body weight, body composition (including fat, lean and muscle mass), muscle function and treadmill running. Circulating myostatin was measured in patient samples from an advanced NSCLC clinical study. Results Anti‐myostatin antibody treatment had limited efficacy in improving cachexia in mouse tumour models with high circulating GDF‐15 (HT‐1080 and RENCA), but improved cachexia (when combined with anti‐GDF‐15 antibody) in a tumour model with low circulating GDF‐15 levels (TOV21G). In the TOV21G model, combining anti‐myostatin and anti‐GDF‐15 antibodies led to even greater increases in body weight and hindlimb muscle mass compared with anti‐GDF‐15 antibody alone (p < 0.001 for muscle mass); however, the increase in muscle strength and treadmill running did not reach statistical significance over monotherapy. When anamorelin was combined with anti‐GDF‐15 antibody, body weight was elevated compared with the HT‐1080 tumour‐bearing vehicle group (p < 0.0001) but did not reach statistical significance over anti‐GDF‐15 antibody alone. Similar observations of the combination treatment were found for food intake, fat mass and gastrocnemius (p < 0.05). Circulating myostatin was negatively correlated with weight loss in patients with cancer (p < 0.01). Conclusion These data provide proof‐of‐principle that mechanistically distinct approaches targeting muscle anabolism and appetite may act additively with GDF‐15 neutralization, particularly in cancer cachexia settings with lower GDF‐15 dependence. Trial Registration: ClinicalTrials.gov identifier: NCT01360554.

AIMS:Two general phenotypes of heart failure (HF) are recognized: HF with reduced ejection fraction (HFrEF) and with preserved EF (HFpEF). To develop phenotype-specific approaches to treatment, distinguishing biomarkers are needed. The goal of this study was to utilize quantitative metabolomics on a large, diverse population to replicate and extend existing knowledge of the plasma metabolic signatures in human HF. METHODS:Plasma metabolomics and proteomics was conducted on 787 samples collected by the Penn Medicine BioBank from subjects with HFrEF (n = 219), HFpEF (n = 357) and matched controls (n = 211). A total of 90 metabolites were analysed, comprising 28 amino acids, 8 organic acids and 54 acylcarnitines. Seven hundred thirty-three of these samples also underwent proteomic profiling via the O-Link proteomics panel. RESULTS:Unsaturated forms of medium-/long-chain acylcarnitines were elevated in the HFrEF group. Amino acid derivatives, including 1- and 3-methylhistidine, homocitrulline and symmetric and asymmetric (ADMA) dimethylarginine were elevated in HF, with ADMA elevated uniquely in HFpEF. While the branched-chain amino acids (BCAAs) were minimally changed, short-chain acylcarnitine species indicative of BCAA catabolism were elevated in both HF groups. 3-hydroxybutyrate (3-HBA) and its metabolite, C4-OH carnitine, were uniquely elevated in the HFrEF group. Linear regression models demonstrated a significant correlation between plasma 3-HBA and N-terminal pro-brain natriuretic peptide in both forms of HF, stronger in HFrEF. CONCLUSIONS:These results identify plasma signatures that are shared as well as potentially distinguish HFrEF and HFpEF. Metabolite markers for ketogenic metabolic re-programming were identified as unique signatures in the HFrEF group, possibly related to increased levels of BNP. Our results set the stage for future studies aimed at assessing selected metabolites as relevant biomarkers to guide HF phenotype-specific therapeutics.

Objective The type 1 interferon (IFN) pathway is up‐regulated in dermatomyositis (DM). We sought to define how organ‐specific disease activity as well as autoantibodies and other clinical factors are independently associated with systemic type I IFN activity in adult patients with DM. Methods RNA sequencing was performed on 355 whole blood samples collected from 202 well‐phenotyped DM patients followed up during the course of their clinical care. A previously defined 13‐gene type I IFN score was modeled as a function of demographic, serologic, and clinical variables using both cross‐sectional and longitudinal data. Results The pattern of type I IFN–driven transcriptional response was stereotyped across samples with a sequential modular activation pattern strikingly similar to systemic lupus erythematosus. The median type I IFN score was higher or lower in patients with anti–melanoma differentiation–associated protein 5 (anti–MDA‐5) or anti–Mi‐2 antibodies, respectively, compared to patients without these antibodies. Absolute type I IFN score was independently associated with muscle and skin disease activity, interstitial lung disease, and anti–MDA‐5 antibodies. Changes in the type I IFN score over time were significantly associated with changes in skin or muscle disease activity. Stratified analysis accounting for heterogeneity in organ involvement and antibody class revealed high correlation between changes in the type I IFN score and skin disease activity (Spearman's ρ = 0.84–0.95). Conclusion The type I IFN score is independently associated with skin and muscle disease activity as well as certain clinical and serologic features in DM. Accounting for the effect of muscle disease and anti–MDA‐5 status revealed that the type I IFN score is strongly correlated with skin disease activity, providing support for type I IFN blockade as a therapeutic strategy for DM. image

Blocking chemokine receptor C-C chemoattractant cytokine (chemokine) receptor (CCR) 6-dependent T cell migration has therapeutic promise in inflammatory diseases. PF-07054894 is a novel CCR6 antagonist that blocked only CCR6, CCR7, and C-X-C chemoattractant cytokine (chemokine) receptor (CXCR) 2 in a β-arrestin assay panel of 168 G protein-coupled receptors. Inhibition of CCR6-mediated human T cell chemotaxis by (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) was insurmountable by CCR6 ligand, C-C motif ligand (CCL) 20. In contrast, blockade of CCR7-dependent chemotaxis in human T cells and CXCR2-dependent chemotaxis in human neutrophils by PF-07054894 were surmountable by CCL19 and C-X-C motif ligand 1, respectively. [3H]-PF-07054894 showed a slower dissociation rate for CCR6 than for CCR7 and CXCR2 suggesting that differences in chemotaxis patterns of inhibition could be attributable to offset kinetics. Consistent with this notion, an analog of PF-07054894 with fast dissociation rate showed surmountable inhibition of CCL20/CCR6 chemotaxis. Furthermore, pre-equilibration of T cells with PF-07054894 increased its inhibitory potency in CCL20/CCR6 chemotaxis by 10-fold. The functional selectivity of PF-07054894 for inhibition of CCR6 relative to CCR7 and CXCR2 is estimated to be at least 50- and 150-fold, respectively. When administered orally to naïve cynomolgus monkeys, PF-07054894 increased the frequency of CCR6+ peripheral blood T cells, suggesting that blockade of CCR6 inhibited homeostatic migration of T cells from blood to tissues. PF-07054894 inhibited interleukin-23-induced mouse skin ear swelling to a similar extent as genetic ablation of CCR6. PF-07054894 caused an increase in cell surface CCR6 in mouse and monkey B cells, which was recapitulated in mouse splenocytes in vitro. In conclusion, PF-07054894 is a potent and functionally selective CCR6 antagonist that blocks CCR6-mediated chemotaxis in vitro and in vivo. SIGNIFICANCE STATEMENT: The chemokine receptor, C-C chemoattractant cytokine (chemokine) receptor 6 (CCR6) plays a key role in the migration of pathogenic lymphocytes and dendritic cells into sites of inflammation. (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) is a novel CCR6 small molecule antagonist that illustrates the importance of binding kinetics in achieving pharmacological potency and selectivity. Orally administered PF-07054894 blocks homeostatic and pathogenic functions of CCR6, suggesting that it is a promising therapeutic agent for the treatment of a variety of autoimmune and inflammatory diseases.

Glycerol-3-phosphate acyltransferase (GPAT)1 is a mitochondrial outer membrane protein that catalyzes the first step of de novo glycerolipid biosynthesis. Hepatic expression of GPAT1 is linked to liver fat accumulation and the severity of nonalcoholic fatty liver diseases. Here we present the cryo-EM structures of human GPAT1 in substrate analog-bound and product-bound states. The structures reveal an N-terminal acyltransferase domain that harbors important catalytic motifs and a tightly associated C-terminal domain that is critical for proper protein folding. Unexpectedly, GPAT1 has no transmembrane regions as previously proposed but instead associates with the membrane via an amphipathic surface patch and an N-terminal loop-helix region that contains a mitochondrial-targeting signal. Combined structural, computational and functional studies uncover a hydrophobic pathway within GPAT1 for lipid trafficking. The results presented herein lay a framework for rational inhibitor development for GPAT1.

Growth differentiation factor 15 (GDF15) causes anorexia and weight loss in animal models, and higher circulating levels are associated with cachexia and reduced survival in cancer and other chronic diseases such as sepsis. To investigate the role of sepsis-induced GDF15, we examined whether GDF15 neutralization via a validated and highly potent monoclonal antibody, mAB2, modulates lipopolysaccharide (LPS)-induced anorexia, weight loss, and mortality in rodents. LPS injection transiently increased circulating GDF15 in wild-type mice, decreased food intake and body weight, and increased illness behavior and mortality at a high dose. GDF15 neutralization with mAB2 did not prevent or exacerbate any of the effects of LPS. Similarly, in GDF15 knockout mice, the LPS effect on appetite and survival was comparable with that observed in wild-type controls. Therefore, effective inhibition of circulating active GDF15 via an antibody or via gene knockout demonstrated that survival in the LPS acute inflammation model was independent of GDF15.

SUMMARY Growth differentiation factor 15 (GDF15) causes anorexia and weight loss in animal models, and higher circulating levels are associated with cachexia and reduced survival in cancer and other chronic diseases such as sepsis. To investigate the role of sepsis-induced GDF15, we examined whether GDF15 neutralization via a validated and highly potent monoclonal antibody, mAB2, modulates lipopolysaccharide (LPS)-induced anorexia, weight loss, and mortality in rodents. LPS injection transiently increased circulating GDF15 in wildtype mice, decreased food intake and body weight, and increased illness behavior and mortality at a high dose. GDF15 neutralization with mAB2 did not prevent or exacerbate any of the effects of LPS. Similarly, in GDF15 knockout mice, the LPS effect on appetite and survival was comparable to that observed in wildtype controls. Therefore, effective inhibition of circulating active GDF15 via antibody or via gene knockout demonstrated that survival in the LPS acute inflammation model was independent of GDF15.

e24162 Background: Platinum-based drug use in cancer treatment is restricted by dose-limiting side effects, including nausea/emesis, anorexia and weight loss that reduce patient quality of life and limit treatment adherence. Cisplatin increases GDF-15, a cytokine that induces aversion, anorexia and weight loss in preclinical models. GDF-15 signals through the hindbrain receptor glial cell-derived neurotrophic factor receptor alpha-like (GFRAL) and cisplatin-induced weight loss was attenuated in a GFRAL knockout mouse. Methods: In the current study, using mouse and/or nonhuman primate models, we examined whether GDF-15 inhibition via a potent and selective monoclonal antibody (mAB1) prevents platinum-induced emesis, anorexia, weight loss, with increased survival. Results: Circulating GDF-15 levels in NSCLC and colorectal cancer were higher (~1.5 fold) in patients on platinum therapy compared to non-platinum-based therapy. Higher levels of circulating GDF-15 were also associated with greater weight loss in colorectal cancer patients prior to receiving FOLFOX as part of cancer treatment. In wildtype mice, cisplatin, oxaliplatin and carboplatin each increased circulating GDF-15 (≥ 5-fold) and induced anorexia, skeletal muscle wasting, and weight loss. These effects were prevented in GDF-15 knockout mice, however only a partial blockade of carboplatin was observed. The GDF-15 neutralizing efficacy of mAB1 was confirmed by reversing AAV-GDF-15-induced weight loss in wildtype mice. In nonhuman primates, cisplatin treatment for 5 days (96% of the daily recommended clinical dose) also increased circulating GDF-15 ( > 5-fold), and induced anorexia and emesis. Treatment with mAB1 resulted in no detectable circulating levels of free GDF-15 and attenuated both cisplatin-induced anorexia and emesis. In a mouse cachectic tumor model (subcutaneous; NSCLC patient derived xenograft), cisplatin inhibited tumor growth; however, GDF-15 levels remained elevated and additional weight loss occurred compared to control. When mAB1 was given in combination with cisplatin, weight loss was reversed and tumor growth inhibition was maintained, resulting in greater survival compared to cisplatin alone. Conclusions: Taken together, these data support that GDF-15 inhibition with mAB1 holds the potential as an effective therapeutic approach to alleviate GDF-15 mediated emesis, anorexia and weight loss, with the aim to enable optimal cancer treatment as well as to improve patient quality of life and potentially survival.

e24153 Background: Growth differentiation factor 15 (GDF-15) is a cytokine that induces anorexia, weight loss and has been reported to be associated with cachexia and poor survival in illnesses characterized by inflammation such as cancer cachexia and heart failure. In preclinical cancer cachexia models, GDF-15 inhibition has been demonstrated to reverse cachexia and improve survival. Circulating GDF-15 is also elevated in patients with sepsis and is associated with increased complications and poor survival. However, the role of infection- and sepsis-induced GDF-15 in mouse models is controversial based on published reports. Methods: In this study, we examined the effect of GDF-15 inhibition on tumor and lipopolysaccharide (LPS)-induced anorexia, weight loss, and survival using a GDF-15 neutralizing antibody (mAB2) and GDF-15 knockout mice. Results: mAB2 efficacy was confirmed by reversing AAV-GDF-15-induced weight loss in wildtype mice. A cachectic (anorexia and weight loss) mouse tumor model was established with subcutaneous implantation of mouse renal cell carcinoma (RENCA) cells. The chemotherapy sorafenib was administered to slow tumor progression. Plasma GDF-15 was increased to ~2 ng/mL, similar to levels in cancer patients. Treatment with mAB2 rapidly reversed both anorexia and weight loss in the tumor-bearing mice. LPS injection (intraperitoneal, 5 mg/kg) increased circulating GDF-15 in wildtype mice reaching concentrations like that reported in septic patients within 90 minutes and remaining elevated after 48 hours (~1 ng/mL). LPS decreased food intake, body weight, and increased mortality (~20%). Different from the tumor model, GDF-15 neutralization with mAB2 did not prevent or exacerbate any of the effects of LPS. There were no observed detrimental effects of mAB2 treatment in either model. Similarly, in GDF-15 knockout mice the LPS effect on energy balance and survival was comparable to that observed in wildtype controls. Plasma GDF-15 was undetectable in the GDF-15 knockout mice. Conclusions: Taken together, these data suggest that GDF-15 is a critical regulator of energy balance and survival in selective pathophysiological states associated with weight loss.

Abstract Platinum-based chemotherapy is associated with nausea/emesis, anorexia and weight loss which reduce patient quality of life and limit treatment adherence potentially leading to poor treatment outcomes. Cisplatin increases circulating growth differentiation factor 15 (GDF-15), a cytokine that induces conditioned taste aversion, anorexia and weight loss in preclinical models. GDF-15 signals through the hindbrain receptor glial cell-derived neurotrophic factor receptor alpha-like (GFRAL). Cisplatin-induced anorexia/weight loss was attenuated in a GFRAL knockout mouse; therefore, we examined whether GDF-15 inhibition can prevent platinum-based chemotherapy-induced emesis, anorexia and weight loss, and also increase survival using mouse and/or nonhuman primate models. In cancer patients, platinum treatment increased circulating GDF-15 in non small cell lung carcinoma, colorectal, and ovarian cancer (~1.5 fold) compared to those receiving a non-platinum-based therapy. Furthermore, cisplatin, oxaliplatin and carboplatin administered individually all increased circulating GDF-15 in wildtype mice (≥ 5 fold) and induced anorexia, skeletal muscle wasting, and weight loss. GDF-15 mRNA was increased in kidney, liver, brain and white adipose tissue. These effects were prevented in GDF-15 knockout mice, however only a partial blockade was observed in the carboplatin group. In nonhuman primates, cisplatin treatment for 5 days (96% of the daily recommended clinical dose) also increased circulating GDF-15 (> 5 fold), and induced anorexia and emesis. Treatment with the anti-GDF-15 monoclonal antibody (mAB1) resulted in no detectable circulating levels of free GDF-15, and attenuated both cisplatin-induced anorexia and emesis. Furthermore, in a mouse cachectic tumor model (subcutaneous implantation of tumor tissue derived from human non-small cell lung carcinoma adenocarcinoma), cisplatin treatment inhibited tumor growth; however, GDF-15 levels were still elevated and additional weight loss occurred compared to vehicle control. When mAB1 was given in combination with cisplatin, weight loss was reversed and tumor growth inhibition was maintained, resulting in greater survival compared to cisplatin alone. Taken together, these data support the notion that GDF-15 inhibition with mAB1 holds the potential as an effective therapeutic approach to alleviate GDF-15 mediated emesis, anorexia and weight loss with the aim to enable optimal cancer treatment as well as to improve patient quality of life and potentially survival. Citation Format: Danna M. Breen, Kevin Beaumont, Donald Bennett, Julia Brosnan, Roberto Calle, Jeffrey R. Chabot, Susie Collins, Teresa Cunio, Ryan M. Esquejo, Stephanie Joaquim, Alison Joyce, Hanna Kim, Laura Lin, Betty Pettersen, Shuxi Qiao, Michelle Rossulek, Brendan Tierney, Karen M. Walters, Gregory Weber, Zhidan Wu, Bei B. Zhang, Morris J. Birnbaum. Growth differentiation factor 15 (GDF-15) inhibition attenuates platinum-based chemotherapy-induced emesis, anorexia and weight loss and increases survival [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3056.

Platinum-based cancer therapy is restricted by dose-limiting side effects and is associated with elevation of growth differentiation factor 15 (GDF-15). But whether this elevation contributes to such side effects has been unclear. Here, we explored the effects of GDF-15 blockade on platinum-based chemotherapy-induced emesis, anorexia, and weight loss in mice and/or nonhuman primate models. We found that circulating GDF-15 is higher in subjects with cancer receiving platinum-based chemotherapy and is positively associated with weight loss in colorectal cancer (NCT00609622). Further, chemotherapy agents associated with high clinical emetic score induce circulating GDF-15 and weight loss in mice. Platinum-based treatment-induced anorexia and weight loss are attenuated in GDF-15 knockout mice, while GDF-15 neutralization with the monoclonal antibody mAB1 improves survival. In nonhuman primates, mAB1 treatment attenuates anorexia and emesis. These results suggest that GDF-15 neutralization is a potential therapeutic approach to alleviate chemotherapy-induced side effects and improve the quality of life.

Interferon signaling is upregulated in dermatomyositis and thought to play a role in pathogenesis. An interferon gene signature in peripheral blood of dermatomyositis patients correlates with skin disease. However, studies have not analyzed how interferon signaling differs across dermatomyositis subtypes or with multiple organ system involvement. We hypothesized that strength and clinical utility of the dermatomyositis blood interferon signature depends on autoantibody subtype and clinical factors. Utilizing RNA sequencing of 377 blood samples derived from a cohort of 205 clinically phenotyped dermatomyositis patients, we found that blood interferon score is significantly elevated in the anti-MDA5 subtype compared to other subtypes (average 16.12, P<0.001). Change in cutaneous disease area and severity index-activity correlates most strongly with change in interferon score in anti-MDA5 (R=0.85, P<0.001) patients, followed by anti-Tif-1g (R=0.59, P<0.001) and anti-SAE1 (R=0.64, P=0.048). The correlation is weak in anti-Mi2 and anti-NXP2 subtypes. These patterns persist after adjustment for lung disease, muscle disease, cancer, and medications. The correlation is stronger when baseline interferon score is greater than 1.5 (R=0.59, P<0.001). The correlation is weaker in patients with active muscle disease and stronger in patients with active lung disease but is unaffected by cancer status. Using a large prospective dataset of DM patients, we demonstrate that interferon-driven gene expression as an activity measure in dermatomyositis is related to specific autoantibody subtypes and is impacted by clinical factors. Careful attention to antibody status and clinical factors could help inform interpretation of interferon biomarker data in future clinical trials.

The antiinflammatory effects of i.v. Ig (IVIG) in the treatment of autoimmune disease are due, in part, to the Fc fragments of Ig aggregates. In order to capitalize on the known antiinflammatory and tolerogenic properties of Ig Fc aggregates, we created a recombinant human IgG1 Fc multimer, GL-2045. In vitro, GL-2045 demonstrated high-avidity binding to Fc receptors, blocked the binding of circulating immune complexes from patients with rheumatoid arthritis to human Fcγ receptors (FcγRs), and inhibited antibody-mediated phagocytosis at log order-lower concentrations than IVIG. In vivo, administration of GL-2045 conferred partial protection against antibody-mediated platelet loss in a murine immune thrombocytopenic purpura (ITP) model. GL-2045 also suppressed disease activity in a therapeutic model of murine collagen-induced arthritis (CIA), which was associated with reduced circulating levels of IL-6. Furthermore, GL-2045 administration to nonhuman primates (NHPs) transiently increased systemic levels of the antiinflammatory cytokines IL-10 and IL-1RA, reduced the proinflammatory cytokine IL-8, and decreased surface expression of CD14 and HLA-DR on monocytes. These findings demonstrate the immunomodulatory properties of GL-2045 and suggest that it has potential as a treatment for autoimmune and inflammatory diseases, as a recombinant alternative to IVIG.

Myostatin is a highly conserved protein secreted primarily from skeletal muscle that can potently suppress muscle growth. This ability to regulate skeletal muscle mass has sparked intense interest in the development of anti-myostatin therapies for a wide array of muscle disorders including sarcopenia, cachexia and genetic neuromuscular diseases. While a number of studies have examined the circulating myostatin concentrations in healthy and sarcopenic populations, very little data are available from inherited muscle disease patients. Here, we have measured the myostatin concentration in serum from seven genetic neuromuscular disorder patient populations using immunoaffinity LC–MS/MS. Average serum concentrations of myostatin in all seven muscle disease patient groups were significantly less than those measured in healthy controls. Furthermore, circulating myostatin concentrations correlated with clinical measures of disease progression for five of the muscle disease patient populations. These findings greatly expand the understanding of myostatin in neuromuscular disease and suggest its potential utility as a biomarker of disease progression.

BACKGROUND:Identifying translatable, non-invasive biomarkers of muscular dystrophy that better reflect the disease pathology than those currently available would aid the development of new therapies, the monitoring of disease progression and the response to therapy. OBJECTIVE:The goal of this study was to evaluate a panel of serum protein biomarkers with the potential to specifically detect skeletal muscle injury. METHOD:Serum concentrations of skeletal troponin I (sTnI), myosin light chain 3 (Myl3), fatty acid binding protein 3 (FABP3) and muscle-type creatine kinase (CKM) proteins were measured in 74 Duchenne muscular dystrophy (DMD), 38 Becker muscular dystrophy (BMD) and 49 Limb-girdle muscular dystrophy type 2B (LGMD2B) patients and 32 healthy controls. RESULTS:All four proteins were significantly elevated in the serum of these three muscular dystrophy patient populations when compared to healthy controls, but, interestingly, displayed different profiles depending on the type of muscular dystrophy. Additionally, the effects of patient age, ambulatory status, cardiac function and treatment status on the serum concentrations of the proteins were investigated. Statistical analysis revealed correlations between the serum concentrations and certain clinical endpoints including forced vital capacity in DMD patients and the time to walk ten meters in LGMD2B patients. Serum concentrations of these proteins were also elevated in two preclinical models of muscular dystrophy, the mdx mouse and the golden-retriever muscular dystrophy dog. CONCLUSIONS:These proteins, therefore, are potential muscular dystrophy biomarkers for monitoring disease progression and therapeutic response in both preclinical and clinical studies.

We applied broad-based phenotypic profiling to identify pharmacodynamic markers for interferon-beta in multiple sclerosis subjects. A strong pharmacodynamic effect was observed 1.5 (short-term) vs. 6 days post weekly injection. Hundreds of differences were observed at a p-value <0.001. Most major cell populations, including neutrophils, B cells, CD4 T cells and CD8 T cells, decreased in absolute counts at 1.5 days. The striking exception was monocytes, which increased substantially. Changes in multiple monocyte-associated cell surface molecules and monocyte related soluble factors were also observed, including: HLA class II, CCR5, CD38, CD40, CD54, CD64, CD69, CD86, CD101, TLR2, TLR4 and MCP2. These results demonstrate that new hypotheses can be generated from broad molecular and cellular profiling in a clinical setting and provide an approach to identify candidate pharmacodynamic markers to evaluate new drug formulations, dosing and bioequivalence.

Persistent high-titre neutralizing antibodies (NAB) to therapeutic interferon-β (IFNβ) in multiple sclerosis patients reduce therapeutic efficacy. Difficulties in standardization of cell-based bioactivity assays have hindered interlaboratory comparison of NAB titres and the determination of a clinically relevant definition of seropositivity. We determined NAB status in Australasian multiple sclerosis patients receiving IFNβ using both the antiviral cytopathic effect (CPE) assay (n = 227) and the more specific ELISA for the type I interferon-inducible MxA protein (n = 350). While the log10 titres determined in the two assays were highly correlated (p < 0.0001; r = 0.967) with similar distributions, the MxA assay was more sensitive, detecting lower concentrations of NAB than the CPE assay. The range of titres determined in the CPE assay was 10 to > 7290; and 9 to 53,700 in the MxA assay, with ranked titre distribution highlighting the arbitrary nature of currently accepted definitions of NAB seropositivity. Bioactivity of injected IFNβ was significantly reduced in NAB-positive patients (p = 0.006; NAB MxA titres = 184 to 5340) compared to NAB-negative patients as assessed ex vivo using real-time RT-PCR analysis of MxA gene induction. The range of MxA mRNA levels in healthy controls was remarkably consistent with previously published results, regardless of the assay standardization method [Gilli, F., Sala, A., Marnetto, F., Lindberg, R.L., Leppert, D. and Bertolotto, A. (2003) Comparison of IFNbeta bioavailability evaluations by MxA mRNA using two independent quantification methods. Abstract, ECTRIMS Meeting, Milan, Italy; Pachner, A., Narayan, K., Price, N., Hurd, M. and Dail, D. (2003a) MxA Gene Expression Analysis as an Interferon-beta Bioactivity Measurement in Patients with Multiple Sclerosis and the Identification of Antibody-Mediated Decreased Bioactivity. Mol. Diagn. 7, 17–25]. Assessment of IFNβ response ex vivo accounts for both circulating factors and the cellular response to IFNβ, and the data support the development of the MxA gene induction assay for the routine screening of patients receiving IFNβ.

To gauge the experimental variability associated with Biacore analysis, 36 different investigators analyzed a small molecule/enzyme interaction under similar conditions. Acetazolamide (222 g/mol) binding to carbonic anhydrase II (CAII; 30000 Da) was chosen as a model system. Both reagents were stable and their interaction posed a challenge to measure because of the low molecular weight of the analyte and the fast association rate constant. Each investigator created three different density surfaces of CAII and analyzed an identical dilution series of acetazolamide (ranging from 4.1 to 1000 nM). The greatest variability in the results was observed during the enzyme immobilization step since each investigator provided their own surface activating reagents. Variability in the quality of the acetazolamide binding responses was likely a product of how well the investigators' instruments had been maintained. To determine the reaction kinetics, the responses from the different density surfaces were fit globally to a 1:1 interaction model that included a term for mass transport. The averaged association and dissociation rate constants were 3.1+/-1.6 x 10(6)M(-1)s(-1) and 6.7+/-2.5 x 10(-2)s(-1), respectively, which corresponded to an average equilibrium dissociation constant (K(D) of 2.6+/-1.4 x 10(-8)M. The results provide a benchmark of variability in interpreting binding constants from the biosensor and highlight keys areas that should be considered when analyzing small molecule interactions.