Pharmacological inhibition of VEGF-A has proven to be effective in inhibiting angiogenesis and vascular leak associated with cancers and various eye diseases. However, little information is currently ...available on the binding kinetics and relative biological activity of various VEGF inhibitors. Therefore, we have evaluated the binding kinetics of two anti-VEGF antibodies, ranibizumab and bevacizumab, and VEGF Trap (also known as aflibercept), a novel type of soluble decoy receptor, with substantially higher affinity than conventional soluble VEGF receptors. VEGF Trap bound to all isoforms of human VEGF-A tested with subpicomolar affinity. Ranibizumab and bevacizumab also bound human VEGF-A, but with markedly lower affinity. The association rate for VEGF Trap binding to VEGF-A was orders of magnitude faster than that measured for bevacizumab and ranibizumab. Similarly, in cell-based bioassays, VEGF Trap inhibited the activation of VEGFR1 and VEGFR2, as well as VEGF-A induced calcium mobilization and migration in human endothelial cells more potently than ranibizumab or bevacizumab. Only VEGF Trap bound human PlGF and VEGF-B, and inhibited VEGFR1 activation and HUVEC migration induced by PlGF. These data differentiate VEGF Trap from ranibizumab and bevacizumab in terms of its markedly higher affinity for VEGF-A, as well as its ability to bind VEGF-B and PlGF.
Abstract
Context
Daily growth hormone (GH) injections can be burdensome for patients and carers. Somapacitan is a long-acting, reversible albumin-binding GH derivative in development for once-weekly ...administration in patients with growth hormone deficiency (GHD).
Objective
The objective of this study is to evaluate the efficacy, safety, and tolerability of once-weekly somapacitan vs once-daily GH.
Design
REAL 3 is a multicenter, randomized, controlled, double-blind (somapacitan doses), phase 2 study with a 26-week main and 26-week extension phase (NCT02616562).
Setting
This study took place at 29 sites in 11 countries.
Patients
Fifty-nine GH treatment-naive prepubertal children with GHD were randomly assigned; 58 completed the trial.
Interventions
Interventions comprised 3 somapacitan doses (0.04 n = 16, 0.08 n = 15, or 0.16 mg/kg/wk n = 14) and daily GH (0.034 mg/kg/d n = 14), administered subcutaneously.
Main Outcome Measures
The primary end point was height velocity (HV) at week 26. Secondary efficacy end points included HV SD score (SDS) and insulin-like growth factor-I (IGF-I) SDS.
Results
At week 26, mean (SD) annualized HV for the somapacitan groups was 8.0 (2.0), 10.9 (1.9), and 12.9 (3.5) cm/year, respectively, vs 11.4 (3.3) cm/year for daily GH; estimated treatment difference (somapacitan 0.16 mg/kg/week—daily GH): 1.7 95% CI –0.2 to 3.6 cm/year. HV was sustained at week 52, and significantly greater with somapacitan 0.16 mg/kg/week vs daily GH. Mean (SD) change from baseline in HV SDS at week 52 was 4.72 (2.79), 6.14 (3.36), and 8.60 (3.15) for the somapacitan groups, respectively, vs 7.41 (4.08) for daily GH. Model-derived mean (SD) IGF-I SDS for the somapacitan groups was −1.62 (0.86), −1.09 (0.78), and 0.31 (1.06), respectively, vs −0.40 (1.50) observed for daily GH. Safety and tolerability were consistent with the profile of daily GH.
Conclusions
In children with GHD, once-weekly somapacitan 0.16 mg/kg/week provided the closest efficacy match with similar safety and tolerability to daily GH after 26 and 52 weeks of treatment. A short visual summary of our work is available (1).
Summary
Objective
To evaluate the safety, local tolerability, pharmacodynamics and pharmacokinetics of escalating single doses of once‐weekly somapacitan, a reversible, albumin‐binding GH derivative, ...vs once‐daily GH in children with GH deficiency (GHD).
Design
Phase 1, randomized, open‐label, active‐controlled, dose‐escalation trial (NCT01973244).
Patients
Thirty‐two prepubertal GH‐treated children with GHD were sequentially randomized 3:1 within each of four cohorts to a single dose of somapacitan (0.02, 0.04, 0.08 and 0.16 mg/kg; n=6 each), or once‐daily Norditropin® SimpleXx® (0.03 mg/kg; n=2 each) for 7 days.
Measurements
Pharmacokinetic and pharmacodynamic profiles were assessed.
Results
Adverse events were all mild, and there were no apparent treatment‐dependent patterns in type or frequency. Four mild transient injection site reactions were reported in three of 24 children treated with somapacitan. No antisomapacitan/anti‐human growth hormone (hGH) antibodies were detected. Mean serum concentrations of somapacitan increased in a dose‐dependent but nonlinear manner: maximum concentration ranged from 21.8 ng/mL (0.02 mg/kg dose) to 458.4 ng/mL (0.16 mg/kg dose). IGF‐I and IGFBP‐3, and change from baseline in IGF‐I standard deviation score (SDS) and IGFBP‐3 SDS, increased dose dependently; greatest changes in SDS values were seen for 0.16 mg/kg. IGF‐I SDS values were between −2 and +2 SDS, except for peak IGF‐I SDS with 0.08 mg/kg somapacitan. Postdosing, IGF‐I SDS remained above baseline levels for at least 1 week.
Conclusions
Single doses of once‐weekly somapacitan (0.02‐0.16 mg/kg) were well tolerated in children with GHD, with IGF‐I profiles supporting a once‐weekly treatment profile. No clinically significant safety/tolerability signals or immunogenicity concerns were identified.
During experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis associated with blood-brain barrier (BBB) disruption, oligodendrocyte precursor cells (OPCs) overexpress ...proteoglycan nerve/glial antigen 2 (NG2), proliferate, and make contacts with the microvessel wall. To explore whether OPCs may actually be recruited within the neurovascular unit (NVU), de facto intervening in its cellular and molecular composition, we quantified by immunoconfocal morphometry the presence of OPCs in contact with brain microvessels, during postnatal cerebral cortex vascularization at postnatal day 6, in wild-type (WT) and NG2 knock-out (NG2KO) mice, and in the cortex of adult naïve and EAE-affected WT and NG2KO mice. As observed in WT mice during postnatal development, a higher number of juxtavascular and perivascular OPCs was revealed in adult WT mice during EAE compared to adult naïve WT mice. In EAE-affected mice, OPCs were mostly associated with microvessels that showed altered claudin-5 and occludin tight junction (TJ) staining patterns and barrier leakage. In contrast, EAE-affected NG2KO mice, which did not show any significant increase in vessel-associated OPCs, seemed to retain better preserved TJs and BBB integrity. As expected, absence of NG2, in both OPCs and pericytes, led to a reduced content of vessel basal lamina molecules, laminin, collagen VI, and collagen IV. In addition, analysis of the major ligand/receptor systems known to promote OPC proliferation and migration indicated that vascular endothelial growth factor A (VEGF-A), platelet-derived growth factor-AA (PDGF-AA), and the transforming growth factor-β (TGF-β) were the molecules most likely involved in proliferation and recruitment of vascular OPCs during EAE. These results were confirmed by real time-PCR that showed Fgf2, Pdgfa and Tgfb expression on isolated cerebral cortex microvessels and by dual RNAscope-immunohistochemistry/in situ hybridization (IHC/ISH), which detected Vegfa and Vegfr2 transcripts on cerebral cortex sections. Overall, this study suggests that vascular OPCs, in virtue of their developmental arrangement and response to neuroinflammation and growth factors, could be integrated among the classical NVU cell components. Moreover, the synchronized activation of vascular OPCs and pericytes during both BBB development and dysfunction, points to NG2 as a key regulator of vascular interactions.
α/βKlotho coreceptors simultaneously engage fibroblast growth factor (FGF) hormones (FGF19, FGF21 and FGF23)
and their cognate cell-surface FGF receptors (FGFR1-4) thereby stabilizing the endocrine ...FGF-FGFR complex
. However, these hormones still require heparan sulfate (HS) proteoglycan as an additional coreceptor to induce FGFR dimerization/activation and hence elicit their essential metabolic activities
. To reveal the molecular mechanism underpinning the coreceptor role of HS, we solved cryo-electron microscopy structures of three distinct 1:2:1:1 FGF23-FGFR-αKlotho-HS quaternary complexes featuring the 'c' splice isoforms of FGFR1 (FGFR1c), FGFR3 (FGFR3c) or FGFR4 as the receptor component. These structures, supported by cell-based receptor complementation and heterodimerization experiments, reveal that a single HS chain enables FGF23 and its primary FGFR within a 1:1:1 FGF23-FGFR-αKlotho ternary complex to jointly recruit a lone secondary FGFR molecule leading to asymmetric receptor dimerization and activation. However, αKlotho does not directly participate in recruiting the secondary receptor/dimerization. We also show that the asymmetric mode of receptor dimerization is applicable to paracrine FGFs that signal solely in an HS-dependent fashion. Our structural and biochemical data overturn the current symmetric FGFR dimerization paradigm and provide blueprints for rational discovery of modulators of FGF signalling
as therapeutics for human metabolic diseases and cancer.
The fibroblast growth factor receptor (FGFR) cascade plays crucial roles in tumor cell proliferation, angiogenesis, migration and survival. Accumulating evidence suggests that in some tumor types, ...FGFRs are bona fide oncogenes to which cancer cells are addicted. Because FGFR inhibition can reduce proliferation and induce cell death in a variety of in vitro and in vivo tumor models harboring FGFR aberrations, a growing number of research groups have selected FGFRs as targets for anticancer drug development. Multikinase FGFR/vascular endothelial growth factor receptor (VEGFR) inhibitors have shown promising activity in breast cancer patients with FGFR1 and/or FGF3 amplification. Early clinical trials with selective FGFR inhibitors, which may overcome the toxicity constraints raised by multitarget kinase inhibition, are recruiting patients with known FGFR(1–4) status based on genomic screens. Preliminary signs of antitumor activity have been demonstrated in some tumor types, including squamous cell lung carcinomas. Rational combination of targeted therapies is expected to further increase the efficacy of selective FGFR inhibitors. Herein, we discuss unsolved questions in the clinical development of these agents and suggest guidelines for management of hyperphosphatemia, a class-specific mechanism-based toxicity. In addition, we propose standardized definitions for FGFR1 and FGFR2 gene amplification based on in situ hybridization methods. Extended access to next-generation sequencing platforms will facilitate the identification of diseases in which somatic FGFR(1–4) mutations, amplifications and fusions are potentially driving cancer cell viability, further strengthening the role of FGFR signaling in cancer biology and providing more possibilities for the therapeutic application of FGFR inhibitors.
Abstract
Placental angiogenesis is critical for normal development. Angiogenic factors and their receptors are key regulators of this process. Dysregulated placental vascular development is ...associated with pregnancy complications. Despite their importance, vascular growth factor expression has not been thoroughly correlated with placental morphologic development across gestation in cats. We postulate that changes in placental vessel morphology can be appreciated as consequences of dynamic expression of angiogenic signaling agents. Here, we characterized changes in placental morphology alongside expression analysis of angiogenic factor splice variants and receptors throughout pregnancy in domestic shorthair cats. We observed increased vascular and lamellar density in the lamellar zone during mid-pregnancy. Immunohistochemical analysis localized the vascular endothelial growth factor A (VEGF-A) receptor KDR to endothelial cells of the maternal and fetal microvasculatures. PlGF and its principal receptor Flt-1 were localized to the trophoblasts and fetal vasculature. VEGF-A was found in trophoblast cells and associated with endothelial cells. We detected expression of two Plgf splice variants and four Vegf-a variants. Quantitative real-time polymerase chain reaction analysis showed upregulation of mRNAs encoding pan Vegf-a and all Vegf-a splice forms at gestational days 30–35. Vegf-A showed a marked relative increase in expression during mid-pregnancy, consistent with the pro-angiogenic changes seen in the lamellar zone at days 30–35. Flt-1 was upregulated during late pregnancy. Plgf variants showed stable expression during the first two-thirds of pregnancy, followed by a marked increase toward term. These findings revealed specific spatiotemporal expression patterns of VEGF-A family members consistent with pivotal roles during normal placental development.
Morphological changes in the placenta during pregnancy correspond to distinctive expression patterns of vascular endothelial growth factor, placental growth factor, and their receptors, suggesting that placental morphologic dynamics are guided by differential expression of these angiogenic factors.
Graphical Abstract
Graphical Abstract
The tumor microenvironment (TME) consists of cancer cells surrounded by stromal components including tumor vessels. Transforming growth factor‐β (TGF‐β) promotes tumor progression by inducing ...epithelial–mesenchymal transition (EMT) in cancer cells and stimulating tumor angiogenesis in the tumor stroma. We previously developed an Fc chimeric TGF‐β receptor containing both TGF‐β type I (TβRI) and type II (TβRII) receptors (TβRI‐TβRII‐Fc), which trapped all TGF‐β isoforms and suppressed tumor growth. However, the precise mechanisms underlying this action have not yet been elucidated. In the present study, we showed that the recombinant TβRI‐TβRII‐Fc protein effectively suppressed in vitro EMT of oral cancer cells and in vivo tumor growth in a human oral cancer cell xenograft mouse model. Tumor cell proliferation and angiogenesis were suppressed in tumors treated with TβRI‐TβRII‐Fc. Molecular profiling of human cancer cells and mouse stroma revealed that K‐Ras signaling and angiogenesis were suppressed. Administration of TβRI‐TβRII‐Fc protein decreased the expression of heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF), interleukin‐1β (IL‐1β) and epiregulin (EREG) in the TME of oral cancer tumor xenografts. HB‐EGF increased proliferation of human oral cancer cells and mouse endothelial cells by activating ERK1/2 phosphorylation. HB‐EGF also promoted oral cancer cell‐derived tumor formation by enhancing cancer cell proliferation and tumor angiogenesis. In addition, increased expressions of IL‐1β and EREG in oral cancer cells significantly enhanced tumor formation. These results suggest that TGF‐β signaling in the TME controls cancer cell proliferation and angiogenesis by activating HB‐EGF/IL‐1β/EREG pathways and that TβRI‐TβRII‐Fc protein is a promising tool for targeting the TME networks.
In the present study, we show that inhibition of transforming growth factor‐β (TGF‐β) signals by recombinant Fc chimeric TGF‐β receptor containing both TGF‐β type I (TβRI) and type II (TβRII) receptors (TβRI‐TβRII‐Fc) suppresses tumor formation through inhibition of cancer cell proliferation and tumor angiogenesis. These results suggest that TβRI‐TβRII‐Fc protein is a promising tool for targeting the various components of tumor microenvironment.
Forest trees display a perennial growth behavior characterized by a multiple-year delay in flowering and, in temperate regions, an annual cycling between growth and dormancy. We show here that the ...CO/FT regulatory module, which controls flowering time in response to variations in daylength in annual plants, controls flowering in aspen trees. Unexpectedly, however, it also controls the short-day-induced growth cessation and bud set occurring in the fall. This regulatory mechanism can explain the ecogenetic variation in a highly adaptive trait: the critical daylength for growth cessation displayed by aspen trees sampled across a latitudinal gradient spanning northern Europe.
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