Evaluation of serum platelet-derived growth factor receptor-ß and brain-derived neurotrophic factor levels in microvascular angina.

OBJECTIVE: Microvascular angina (MVA) is a coronary microcirculation disease. Research on microcirculatory dysfunction has revealed several biomarkers involved in the etiopathogenesis of MVA. Platelet-derived growth factor receptor ß (PDGFR-ß) and brain-derived neurotrophic factor (BDNF) are 2 biomarkers associated with microcirculation, particularly pericytes function. The aim of this study was to investigate the role of PDGFR-ß and BDNF in MVA. METHODS: Ninety-one patients (median age, 56 y; age range, 40-79 y; 36 men) with MVA and 61 control group subjects (median age, 52 y; age range, 38-76 y; 29 men) were included in the study. Serum concentrations of PDGFR-ß and BDNF were measured with commercially available enzyme-linked immunosorbent assay kits. RESULTS: PDGFR-ß [2.82 ng/ml; interquartile range (IQR), 0.57-7.79 ng/ml vs. 2.27 ng/ml; IQR, 0.41-7.16 ng/ml; p<0.0005] and BDNF (2.41 ng/ml; IQR, 0.97-7.97 ng/ml vs. 1.92 ng/ml; IQR, 1.07-6.67 ng/ml; p=0.023) concentrations were significantly higher in patients with MVA compared with the controls. PDGFR-ß correlated positively with age (r=0.26, p=0.001), low-density lipoprotein (r=0.18; p=0.02), and BDNF (r=0.47; p<0.001), and BDNF showed a significant positive correlation with age (r=0.20; p=0.01). In binary logistic regression analysis, high-sensitivity C-reactive protein, uric acid, and PDGFR-ß values were found to be independent predictors of MVA. CONCLUSION: MVA is associated with higher PDGFR-ß and BDNF levels. This association may indicate an abnormality in microvascular function. Future studies are required to determine the role of these biomarkers in the pathogenesis of MVA.

Cleavage of proteoglycans, plasma proteins and the platelet-derived growth factor receptor in the hemorrhagic process induced by snake venom metalloproteinases.

Envenoming by viperid snakes results in a complex pattern of tissue damage, including hemorrhage, which in severe cases may lead to permanent sequelae. Snake venom metalloproteinases (SVMPs) are main players in this pathogenesis, acting synergistically upon different mammalian proteomes. Hemorrhagic Factor 3 (HF3), a P-III class SVMP from Bothrops jararaca, induces severe local hemorrhage at pmol doses in a murine model. Our hypothesis is that in a complex scenario of tissue damage, HF3 triggers proteolytic cascades by acting on a partially known substrate repertoire. Here, we focused on the hypothesis that different proteoglycans, plasma proteins, and the platelet derived growth factor receptor (PDGFR) could be involved in the HF3-induced hemorrhagic process. In surface plasmon resonance assays, various proteoglycans were demonstrated to interact with HF3, and their incubation with HF3 showed degradation or limited proteolysis. Likewise, Western blot analysis showed in vivo degradation of biglycan, decorin, glypican, lumican and syndecan in the HF3-induced hemorrhagic process. Moreover, antithrombin III, complement components C3 and C4, factor II and plasminogen were cleaved in vitro by HF3. Notably, HF3 cleaved PDGFR (alpha and beta) and PDGF in vitro, while both receptor forms were detected as cleaved in vivo in the hemorrhagic process induced by HF3. These findings outline the multifactorial character of SVMP-induced tissue damage, including the transient activation of tissue proteinases, and underscore for the first time that endothelial glycocalyx proteoglycans and PDGFR are targets of SVMPs in the disruption of microvasculature integrity and generation of hemorrhage.

Systemic management of malignant meningiomas: A comparative survival and molecular marker analysis between Octreotide in combination with Everolimus and Sunitinib.

PURPOSE: To compare the effectiveness of octreotide/everolimus vs. sunitinib for the systemic treatment of recurrent aggressive meningiomas. METHODS: 31 patients with recurrent or refractory WHO II or WHO III meningiomas were examined in two reference centers in Colombia. Patients who had systemic treatment (sunitinib, everolimus/octreotide) and a complete follow-up were included. Overall survival (OS), progression-free survival (PFS) and toxicities were evaluated. Additionally, tissue samples were examined for PDGFRß and VEGFR2, their expression was correlated with outcomes. RESULTS: Twenty-two patients (72%) were female with a median age of 55 years (SD±15.3). The most prevalent histology was anaplastic meningioma in 20 patients (65%) with 48% of patients suffering from three previous relapses before the start of systemic treatment. A total of 14 patients received combination therapy with octreotide/everolimus, 11 received sunitinib and the remaining 6 received other second-line agents. Median OS was 37.3 months (95%CI 28.5-42.1) and the PFS during the treatment with everolimus/octreotide (EO) and sunitinib (Su) was 12.1 months (95%CI 9.2-21.1) and 9.1 months (95%CI 6.8-16.8); p = 0.43), respectively. The OS of the group treated with the EO→Su→Bev sequence (1st/2nd/3rd line) was 6.5 months longer than the Su→EO→Bev sequence (36.0 vs. 29.5 months) (p = 0.0001). When analyzing molecular markers, the positive PDGFRß and negative VEGFR2 expression were associated with longer survival both in OS and PFS. CONCLUSION: Sunitinib and octreotide/everolimus have similar efficacy and safety in the systemic management of refractory meningioma. VEGFR2 and PDGFRß expression are associated with better outcomes.

Probing the Virtual Proteome to Identify Novel Disease Biomarkers.

BACKGROUND: Proteomic approaches allow measurement of thousands of proteins in a single specimen, which can accelerate biomarker discovery. However, applying these technologies to massive biobanks is not currently feasible because of the practical barriers and costs of implementing such assays at scale. To overcome these challenges, we used a "virtual proteomic" approach, linking genetically predicted protein levels to clinical diagnoses in >40 000 individuals. METHODS: We used genome-wide association data from the Framingham Heart Study (n=759) to construct genetic predictors for 1129 plasma protein levels. We validated the genetic predictors for 268 proteins and used them to compute predicted protein levels in 41 288 genotyped individuals in the Electronic Medical Records and Genomics (eMERGE) cohort. We tested associations for each predicted protein with 1128 clinical phenotypes. Lead associations were validated with directly measured protein levels and either low-density lipoprotein cholesterol or subclinical atherosclerosis in the MDCS (Malmö Diet and Cancer Study; n=651). RESULTS: In the virtual proteomic analysis in eMERGE, 55 proteins were associated with 89 distinct diagnoses at a false discovery rate q<0.1. Among these, 13 associations involved lipid (n=7) or atherosclerosis (n=6) phenotypes. We tested each association for validation in MDCS using directly measured protein levels. At Bonferroni-adjusted significance thresholds, levels of apolipoprotein E isoforms were associated with hyperlipidemia, and circulating C-type lectin domain family 1 member B and platelet-derived growth factor receptor-ß predicted subclinical atherosclerosis. Odds ratios for carotid atherosclerosis were 1.31 (95% CI, 1.08-1.58; P=0.006) per 1-SD increment in C-type lectin domain family 1 member B and 0.79 (0.66-0.94; P=0.008) per 1-SD increment in platelet-derived growth factor receptor-ß. CONCLUSIONS: We demonstrate a biomarker discovery paradigm to identify candidate biomarkers of cardiovascular and other diseases.

Masitinib monotherapy in canine epitheliotropic lymphoma.

This study evaluated efficacy and side effects of masitinib in canine epitheliotropic lymphoma. Complete remission occurred in 2 of 10 dogs and lasted for median 85 days. Five dogs went into partial remission for median 60.5 days. Three pretreated dogs did not respond to therapy. Side effects occurred in six dogs and were mostly mild to moderate. Immunohistochemistry was available for eight dogs. KIT receptor was negative in all of them, six of eight lymphomas stained strongly positive for stem cell factor (SCF). platelet-derived growth factor (PDGF)-AA was weakly positive in two and negative in six. PDGF-BB was negative in four tumours, weakly positive in one and strongly positive in three. One was strongly positive for PDGF receptor (PDGFR)-ß, seven were negative for that receptor. Five showed strong expression of PDGFR-α, two showed weak expression, one was negative. In conclusion, masitinib is effective in treating canine epitheliotropic lymphoma. But its effects are most likely not generated through the KIT receptor.

A pilot study of JI-101, an inhibitor of VEGFR-2, PDGFR-ß, and EphB4 receptors, in combination with everolimus and as a single agent in an ovarian cancer expansion cohort.

JI-101 is an oral multi-kinase inhibitor that targets vascular endothelial growth factor receptor type 2 (VEGFR-2), platelet derived growth factor receptor ß (PDGFR-ß), and ephrin type-B receptor 4 (EphB4). None of the currently approved angiogenesis inhibitors have been reported to inhibit EphB4, and therefore, JI-101 has a novel mechanism of action. We conducted a pilot trial to assess the pharmacokinetics (PK), tolerability, and efficacy of JI-101 in combination with everolimus in advanced cancers, and pharmacodynamics (PD), tolerability, and efficacy of JI-101 in ovarian cancer. This was the first clinical study assessing anti-tumor activity of JI-101 in a combinatorial regimen. In the PK cohort, four patients received single agent 10 mg everolimus on day 1, 10 mg everolimus and 200 mg JI-101 combination on day 8, and single agent 200 mg JI-101 on day 15. In the PD cohort, eleven patients received single agent JI-101 at 200 mg twice daily for 28 day treatment cycles. JI-101 was well tolerated as a single agent and in combination with everolimus. No serious adverse events were observed. Common adverse events were hypertension, nausea, and abdominal pain. JI-101 increased exposure of everolimus by approximately 22%, suggestive of drug-drug interaction. The majority of patients had stable disease at their first set of restaging scans (two months), although no patients demonstrated a response to the drug per RECIST criteria. The novel mechanism of action of JI-101 is promising in ovarian cancer treatment and further prospective studies of this agent may be pursued in a less refractory patient population or in combination with cytotoxic chemotherapy.

Analysis of serum protein biomarkers, circulating tumor DNA, and dovitinib activity in patients with tyrosine kinase inhibitor-refractory gastrointestinal stromal tumors.

BACKGROUND: An exploratory translational analysis was conducted as part of a phase II study of dovitinib to assess the relevance of soluble serum proteins and circulating tumor (ct) DNA (ctDNA) as biomarkers in patients with tyrosine kinase inhibitor (TKI)-refractory gastrointestinal stromal tumors (GISTs). PATIENTS AND METHODS: Predose serum samples were collected from 30 patients on day 1 of cycle 1 and cycle 2. Serum levels of angiogenesis-related proteins were assessed by enzyme-linked immunosorbent assay, and Beads, emulsions, amplification, and magnetics (BEAMing) assays were carried out to detect mutations in serum ctDNA. RESULTS: Dovitinib increased vascular endothelial growth factor (VEGF)165 (1.26-fold, P = 0.006), VEGF-A (1.27-fold, P = 0.004), placental growth factor (6.0-fold, P = 0.002), fibroblast growth factor 23 (1.45-fold, P = 0.02), and interleukin 8 (1.75-fold, P = 0.04) levels, and decreased soluble vascular endothelial growth factor receptor (sVEGFR)-2 levels (0.8-fold, P = 0.001). The changes in sVEGFR-2 were significantly associated with metabolic response determined by positron emission tomography (P = 0.02) and progression-free survival (PFS; P = 0.02). Secondary kinase mutations were identified in the ctDNA of 11 patients (41%), and these patients all had mutations involving KIT exon 17. Patients with secondary KIT mutations had significantly worse overall survival {median, 5.5 months [95% confidence interval (CI) 3.8-7.2 months]} than those with no detectable secondary mutations [9.8 months (95% CI 9.6-10.0 months); hazard ratio = 2.7 (95% CI 1.0-7.3); P = 0.047]. CONCLUSIONS: Changes in sVEGFR-2 levels were associated with dovitinib-mediated antitumor activity. Genotyping of serum ctDNA with BEAMing is useful for the identification of resistant mutations potentially associated with poor prognosis in patients with GISTs.

Platelet-derived growth factor receptor beta serum concentrations during first-line therapy in ovarian cancer.

OBJECTIVES: Angiogenesis plays an important role in ovarian cancer. The interaction of platelet-derived growth factor receptor-beta (PDGFR-ß) with vascular endothelial growth factor (VEGF) in the process of angiogenesis may represent an essential feature in the progression of the disease. METHODS: Patients with epithelial ovarian cancer, who underwent primary surgery and platinum-based first-line chemotherapy, were included. A total of 133 serum samples from 39 patients were analyzed. Samples were prospectively collected at 4 time points: (1) before surgery, (2) after surgery and before chemotherapy, (3) during chemotherapy and (4) after chemotherapy. Serum PDGFR-ß was quantified by ELISA. We analyzed the correlation of serum levels to chemotherapy response, progression-free and overall survival (PFS and OS) and the serum markers CA-125 and VEGF-165. RESULTS: Serum concentration of PDGFR-ß ranged between 4 and 72 ng/ml and increased significantly during first-line chemotherapy (p = 0.019). PDGFR-ß serum concentrations showed an inverse correlation with CA-125 and VEGF-165 after chemotherapy (r = -0.495, p = 0.003 and r = -0.345, p = 0.04, respectively). Increased PDGFR-ß serum levels after chemotherapy were significantly correlated with better PFS (p = 0.026) and OS (p = 0.013) in a univariate analysis. CONCLUSION: PDGFR-ß might be a useful biomarker in terms of prognosis and could be important as antiangiogenic agents become a component of standard treatment in ovarian cancer.

Multipotent PDGFRß-expressing cells in the circulation of stroke patients.

Tissue pericytes respond to injury, and support vascular and tissue regeneration. The presence of pericytes in the circulation may provide an attractive framework for tissue regeneration. Here, we detected multipotent pericyte-like cells in the circulating blood and determined its profiles during cerebral ischemia. Pericyte-like cells were isolated from the peripheral blood of acute stroke patients or asymptomatic individuals with vascular risk factors by fluorescence or magnetic activated cell sorting with anti-PDGF receptor-beta (PDGFRß) antibody. The morphologic and molecular features of circulating PDGFRß(+) cells were compared with tissue pericytes, and the associations with respect to quantity in the blood, culture outcome, and patient characteristics were analyzed. We found an increase in circulating PDGFRß(+) cells in acute stroke patients compared to controls and a correlation with neurologic impairment. The isolated PDGFRß(+) cells expressed mesenchymal stem cell markers, proliferated, and were multipotent under permissive culture conditions. The multipotent nature of these cells was comparable to fat-derived PDGFRß(+) cells. These cells could be obtained by pharmacologic stimulation using bone marrow mobilizer. Circulating PDGFRß(+) cells will be useful for future research involving endogenous recovery or autologous cell-based therapy.

Growth factor concentrations and their placental mRNA expression are modulated in gestational diabetes mellitus: possible interactions with macrosomia.

BACKGROUND: Gestational diabetes mellitus (GDM) is a form of diabetes that occurs during pregnancy. GDM is a well known risk factor for foetal overgrowth, termed macrosomia which is influenced by maternal hypergycemia and endocrine status through placental circulation. The study was undertaken to investigate the implication of growth factors and their receptors in GDM and macrosomia, and to discuss the role of the materno-foeto-placental axis in the in-utero regulation of foetal growth. METHODS: 30 women with GDM and their 30 macrosomic babies (4.75 +/- 0.15 kg), and 30 healthy age-matched pregnant women and their 30 newborns (3.50 +/- 0.10 kg) were recruited in the present study. Serum concentrations of GH and growth factors, i.e., IGF-I, IGF-BP3, FGF-2, EGF and PDGF-B were determined by ELISA. The expression of mRNA encoding for GH, IGF-I, IGF-BP3, FGF-2, PDGF-B and EGF, and their receptors, i.e., GHR, IGF-IR, FGF-2R, EGFR and PDGFR-beta were quantified by using RT-qPCR. RESULTS: The serum concentrations of IGF-I, IGF-BP3, EGF, FGF-2 and PDGF-B were higher in GDM women and their macrosomic babies as compared to their respective controls. The placental mRNA expression of the growth factors was either upregulated (FGF-2 or PDGF-B) or remained unaltered (IGF-I and EGF) in the placenta of GDM women. The mRNA expression of three growth factor receptors, i.e., IGF-IR, EGFR and PDGFR-beta, was upregulated in the placenta of GDM women. Interestingly, serum concentrations of GH were downregulated in the GDM women and their macrosomic offspring. Besides, the expression of mRNAs encoding for GHR was higher, but that encoding for GH was lower, in the placenta of GDM women than control women. CONCLUSIONS: Our results demonstrate that growth factors might be implicated in GDM and, in part, in the pathology of macrosomia via materno-foeto-placental axis.

A new look at platelet-derived growth factor in renal disease.

The PDGF system, comprising four isoforms (PDGF-A, -B, -C, and -D) and two receptor chains (PDGFR-alpha and -beta), plays important roles in wound healing, atherosclerosis, fibrosis, and malignancy. Components of the system are expressed constitutively or inducibly in most renal cells. They regulate a multitude of pathophysiologic events, ranging from cell proliferation and migration to extracellular matrix accumulation, production of pro- and anti-inflammatory mediators, tissue permeability, and regulation of hemodynamics. Genetic deletion of PDGF-B or PDGFR-beta results in an absent glomerular mesangium, whereas PDGF-C and PDGFR-alpha contribute to the formation of the renal cortical interstitium. Almost all experimental and human renal diseases are characterized by altered expression of components of the PDGF system. Infusion or systemic overexpression of PDGF-B or -D induces prominent mesangioproliferative changes and renal fibrosis. Intervention studies identified PDGF-C as a mediator of renal interstitial fibrosis and PDGF-B and -D as key factors involved in mesangioproliferative disease and renal interstitial fibrosis. These data establish PDGF as one of the best characterized growth factors in renal disease and the most potent stimulus of mesangial cell proliferation currently identified. Accordingly, targeted intervention against the various PDGF isoforms offers a promising novel therapeutic approach to renal disease.

Durable responses to imatinib in patients with PDGFRB fusion gene-positive and BCR-ABL-negative chronic myeloproliferative disorders.

Fusion genes derived from the platelet-derived growth factor receptor beta (PDGFRB) or alpha (PDGFRA) play an important role in the pathogenesis of BCR-ABL-negative chronic myeloproliferative disorders (CMPDs). These fusion genes encode constitutively activated receptor tyrosine kinases that can be inhibited by imatinib. Twelve patients with BCR-ABL-negative CMPDs and reciprocal translocations involving PDGFRB received imatinib for a median of 47 months (range, 0.1-60 months). Eleven had prompt responses with normalization of peripheral-blood cell counts and disappearance of eosinophilia; 10 had complete resolution of cytogenetic abnormalities and decrease or disappearance of fusion transcripts as measured by reverse transcriptase-polymerase chain reaction (RT-PCR). Updates were sought from 8 further patients previously described in the literature; prompt responses were described in 7 and persist in 6. Our data show that durable hematologic and cytogenetic responses are achieved with imatinib in patients with PDGFRB fusion-positive, BCR-ABL-negative CMPDs.