Analysis of the Molecular Networks in Androgen Dependent and Independent Prostate Cancer Revealed Fragile and Robust Subsystems

Androgen ablation therapy is currently the primary treatment for metastatic prostate cancer. Unfortunately, in nearly all cases, androgen ablation fails to permanently arrest cancer progression. As androgens like testosterone are withdrawn, prostate cancer cells lose their androgen sensitivity and begin to proliferate without hormone growth factors. In this study, we constructed and analyzed a mathematical model of the integration between hormone growth factor signaling, androgen receptor activation, and the expression of cyclin D and Prostate-Specific Antigen in human LNCaP prostate adenocarcinoma cells. The objective of the study was to investigate which signaling systems were important in the loss of androgen dependence. The model was formulated as a set of ordinary differential equations which described 212 species and 384 interactions, including both the mRNA and protein levels for key species. An ensemble approach was chosen to constrain model parameters and to estimate the impact of parametric uncertainty on model predictions. Model parameters were identified using 14 steady-state and dynamic LNCaP data sets taken from literature sources. Alterations in the rate of Prostatic Acid Phosphatase expression was sufficient to capture varying levels of androgen dependence. Analysis of the model provided insight into the importance of network components as a function of androgen dependence. The importance of androgen receptor availability and the MAPK/Akt signaling axes was independent of androgen status. Interestingly, androgen receptor availability was important even in androgen-independent LNCaP cells. Translation became progressively more important in androgen-independent LNCaP cells. Further analysis suggested a positive synergy between the MAPK and Akt signaling axes and the translation of key proliferative markers like cyclin D in androgen-independent cells. Taken together, the results support the targeting of both the Akt and MAPK pathways. Moreover, the analysis suggested that direct targeting of the translational machinery, specifically eIF4E, could be efficacious in androgen-independent prostate cancers

Computational Modeling and Analysis of Insulin Induced Eukaryotic Translation Initiation

Insulin, the primary hormone regulating the level of glucose in the bloodstream, modulates a variety of cellular and enzymatic processes in normal and diseased cells. Insulin signals are processed by a complex network of biochemical interactions which ultimately induce gene expression programs or other processes such as translation initiation. Surprisingly, despite the wealth of literature on insulin signaling, the relative importance of the components linking insulin with translation initiation remains unclear. We addressed this question by developing and interrogating a family of mathematical models of insulin induced translation initiation. The insulin network was modeled using mass-action kinetics within an ordinary differential equation (ODE) framework. A family of model parameters was estimated, starting from an initial best fit parameter set, using 24 experimental data sets taken from literature. The residual between model simulations and each of the experimental constraints were simultaneously minimized using multiobjective optimization. Interrogation of the model population, using sensitivity and robustness analysis, identified an insulin-dependent switch that controlled translation initiation. Our analysis suggested that without insulin, a balance between the pro-initiation activity of the GTP-binding protein Rheb and anti-initiation activity of PTEN controlled basal initiation. On the other hand, in the presence of insulin a combination of PI3K and Rheb activity controlled inducible initiation, where PI3K was only critical in the presence of insulin. Other well known regulatory mechanisms governing insulin action, for example IRS-1 negative feedback, modulated the relative importance of PI3K and Rheb but did not fundamentally change the signal flow

A Test of Highly Optimized Tolerance Reveals Fragile Cell-Cycle Mechanisms Are Molecular Targets in Clinical Cancer Trials

Robustness, a long-recognized property of living systems, allows function in the face of uncertainty while fragility, i.e., extreme sensitivity, can potentially lead to catastrophic failure following seemingly innocuous perturbations. Carlson and Doyle hypothesized that highly-evolved networks, e.g., those involved in cell-cycle regulation, can be resistant to some perturbations while highly sensitive to others. The “robust yet fragile” duality of networks has been termed Highly Optimized Tolerance (HOT) and has been the basis of new lines of inquiry in computational and experimental biology. In this study, we tested the working hypothesis that cell-cycle control architectures obey the HOT paradigm. Three cell-cycle models were analyzed using monte-carlo sensitivity analysis. Overall state sensitivity coefficients, which quantify the robustness or fragility of a given mechanism, were calculated using a monte-carlo strategy with three different numerical techniques along with multiple parameter perturbation strategies to control for possible numerical and sampling artifacts. Approximately 65% of the mechanisms in the G1/S restriction point were responsible for 95% of the sensitivity, conversely, the G2-DNA damage checkpoint showed a much stronger dependence on a few mechanisms; ∼32% or 13 of 40 mechanisms accounted for 95% of the sensitivity. Our analysis predicted that CDC25 and cyclin E mechanisms were strongly implicated in G1/S malfunctions, while fragility in the G2/M checkpoint was predicted to be associated with the regulation of the cyclin B-CDK1 complex. Analysis of a third model containing both G1/S and G2/M checkpoint logic, predicted in addition to mechanisms already mentioned, that translation and programmed proteolysis were also key fragile subsystems. Comparison of the predicted fragile mechanisms with literature and current preclinical and clinical trials suggested a strong correlation between efficacy and fragility. Thus, when taken together, these results support the working hypothesis that cell-cycle control architectures are HOT networks and establish the mathematical estimation and subsequent therapeutic exploitation of fragile mechanisms as a novel strategy for anti-cancer lead generation

Phase II evaluation of anti-MAdCAM antibody PF-00547659 in the treatment of Crohn's disease: report of the OPERA study.

OBJECTIVE: This phase II, randomised, double-blind, placebo-controlled clinical trial was designed to evaluate the efficacy and safety of PF-00547659, a fully human monoclonal antibody that binds to human mucosal addressin cell adhesion molecule (MAdCAM) to selectively reduce lymphocyte homing to the intestinal tract, in patients with moderate-to-severe Crohn's disease (CD). DESIGN: Eligible adults were aged 18-75 years, with active moderate-to-severe CD (Crohn's Disease Activity Index (CDAI) 220-450), a history of failure or intolerance to antitumour necrosis factor and/or immunosuppressive agents, high-sensitivity C reactive protein >3.0 mg/L and ulcers on colonoscopy. Patients were randomised to PF-00547659 22.5 mg, 75 mg or 225 mg or placebo. The primary endpoint was CDAI 70-point decrease from baseline (CDAI-70) at week 8 or 12. RESULTS: In all, 265 patients were eligible for study entry. Although CDAI-70 response was not significantly different with placebo versus PF-00547659 treatment at weeks 8 or 12, remission rate was greater in patients with higher baseline C reactive protein (>5 mg/L vs >18.8 mg/L, respectively). Soluble MAdCAM decreased significantly from baseline to week 2 in a dose-related manner and remained low during the study in PF-00547659-treated patients. Circulating beta7+ CD4+ central memory T-lymphocytes increased at weeks 8 and 12 with PF-00547659 treatment. No safety signal was seen. CONCLUSIONS: Clinical endpoint differences between PF-00547659 and placebo did not reach statistical significance in patients with moderate-to-severe CD. PF-00547659 was pharmacologically active, as shown by a sustained dose-related decrease in soluble MAdCAM and a dose-related increase in circulating beta7+ central memory T cells. TRIAL REGISTRATION NUMBER: NCT01276509; Results

Peak Thrombin and D-Dimer Levels in Subjects with Severe Hemophilia Receiving Acute Treatment for Bleeding Episodes Experienced during Prophylactic Marstacimab Treatment

Introduction: Marstacimab is a fully humanized monoclonal immunoglobulin G1 that targets the shared K2 domains of tissue factor pathway inhibitor (TFPI)α and (TFPI)β and is currently in phase 3 development. The intended indication is routine prophylaxis treatment to prevent or reduce the frequency of bleeding episodes in patients with hemophilia A or B (with or without inhibitors). Factor replacement or bypass treatment for bleeding events may lead to increased levels of peak thrombin and D-dimer associated with an increased risk of thrombosis . In this post hoc analysis of data from a phase 2 study in patients with hemophilia with and without bleeding episodes, receiving prophylactic marstacimab treatment, peak thrombin and D-dimer levels were investigated to assess the changes in these biomarker levels observed after bleeding episodes. Methods: Individual subject data from the phase 2 study (clinicaltrials.gov identifier: NCT02974855)were used for this analysis. Biomarker data for healthy volunteers who received single doses of marstacimab in a phase 1 dose escalation study (clinicaltrials.gov identifier: NCT02531815) were used as control data, as these subjects represent an intact and uncompromised coagulation system. Study subjects in the phase 2 study received subcutaneous (SC) marstacimab at doses of (1) 150 mg once weekly (QW), with a loading dose of 300 mg, (2) 300 mg QW, and (3) 450 mg QW. All subjects with bleeding episodes were identified, along with on-demand treatment administered for each bleeding episode. Treatments permitted for bleeding episodes included activated coagulation factor VIIa, factor VIII, or factor IX; use of activated prothrombin complex concentrate was prohibited. D-dimer and peak thrombin data collected within 3 days after each bleeding episode were used for this analysis. Time profiles of peak thrombin and D-dimer levels were analyzed to assess the effect of bleed treatment. Biomarker profiles were compared between subjects with and without bleeding episodes, as well as with the data from healthy volunteers (n=41). Results: A total of 15 bleeding episodes were reported in 8 of 26 subjects during the study (excluding screening and follow-up). No subject participating in the study showed any relevant increases in D-dimer levels after receiving on-demand treatment for a bleeding episode while receiving regular prophylaxis with marstacimab, compared with levels seen in subjects who did not experience a bleeding episode. Based on the peak thrombin data (see Figure), 150 nM was observed as the upper limit for 18 of 26 subjects who did not experience any bleeding episodes, which was approximately 50% of the 300 nM observed in healthy volunteer controls treated with 450 mg intravenous marstacimab. Transient increases in peak thrombin of &amp;gt;150 nM were observed at several time points in 3 of 8 subjects who experienced bleeding episodes. The highest peak thrombin level reported was approximately 211 nM in one subject receiving marstacimab 300 mg SC QW and factor VIII concentrate on demand during the study. Conclusions: No transient increases in D-dimer could be attributed to the administration of bleeding episode treatment. The transient increases in peak thrombin levels following on-demand treatment for bleeding episodes did not exceed peak thrombin levels seen in subjects without bleeding events or the levels seen in healthy volunteer controls receiving single doses of marstacimab. Based on peak thrombin and D-dimer levels observed in this post hoc analysis, there does not appear to be any indication of an increased risk of thrombosis post administration of acute on-demand bleeding episode treatment while on prophylactic marstacimab therapy at the doses studied. Disclosures Nayak: Pfizer Inc.: Current Employment, Other. Raje:Pfizer Inc.: Current Employment, Other. Teeter:Pfizer Inc.: Current Employment. Harnisch:Pfizer Inc.: Current Employment, Other. Arkin:Pfizer: Current Employment, Current equity holder in publicly-traded company, Other: own stock/options in the company. </jats:sec

Childhood Vasculitis Syndrome Mimicking Guillain Barre Syndrome

Background: Childhood vasculitis is a heterogeneous disorder, characterized by inflammation of the blood vessel walls. Multiple organs and/or tissues are affected, either simultaneously or successively. Vascular neuropathy occurs when the vasa nervorum is affected. Presentation includes mononeuritis multiplex, acute motor/motor-sensory axonal neuropathy, pure sensory neuropathy, and chronic inflammatory demyelinating polyneuropathy. Making a diagnosis is a challenge when neurological manifestations appear for the first time or are isolated. Clinical Description: A 12-year-old girl presented with acute pain and progressive weakness of both lower limbs for 12 days, followed by diffuse abdominal pain and low-grade fever. Salient neurological findings were diminished power and hyporeflexia in all limbs. Guillain–Barre syndrome was suspected in view of symmetric ascending paralysis and a suggestive nerve conduction study. The child had neutrophilic leukocytosis but sterile cultures. The successive development of inflammatory demyelinating polyneuropathy, persistent fever, vasculitic phenomena (hypertension, severe myalgia, rashes, multiple infarcts, acute renal cortical necrosis, and gangrene of the digit), and elevated acute-phase reactants was suggestive of a multisystemic small-vessel and medium-sized vasculitis syndrome, such as polyarteritis nodosa (PAN). A diagnosis of PAN was established based on the satisfaction of clinical criteria. Management: The patient was administered pulse methylprednisolone and oral steroids, with which there was a dramatic recovery. Monthly cyclophosphamide was continued in view of major systemic involvement. Conclusion: Early recognition and management of childhood vasculitis syndrome is associated with good outcomes