Glial-mediated dysregulation of neurodevelopment in Fragile X Syndrome

Astrocytes are highly involved in a multitude of developmental processes that are known to be dysregulated in Fragile X Syndrome. Here, we examine these processes individually and review the roles astrocytes play in contributing to the pathology of this syndrome. As a growing area of interest in the field, new and exciting insight is continually emerging. Understanding these glial-mediated roles is imperative for elucidating the underlying molecular mechanisms at play, not only in Fragile X Syndrome, but also other ASD-related disorders. Understanding these roles will be central to the future development of effective, clinically-relevant treatments of these disorders.

The clinical effectiveness and cost-effectiveness of cetuximab (mono- or combination chemotherapy), bevacizumab (combination with non-oxaliplatin chemotherapy) and panitumumab (monotherapy) for the treatment of metastatic colorectal cancer after first-line chemotherapy (review of technology appraisal No.150 and part review of technology appraisal No. 118): a systematic review and economic model

BACKGROUND

Colorectal cancer is the third most commonly diagnosed cancer in the UK after breast and lung cancer. People with metastatic disease who are sufficiently fit are usually treated with active chemotherapy as first- or second-line therapy. Recently, targeted agents have become available including anti-epidermal growth factor receptor (EGFR) agents, for example cetuximab and panitumumab, and anti-vascular endothelial growth factor (VEGF) receptor agents, for example bevacizumab.

OBJECTIVE

To investigate the clinical effectiveness and cost-effectiveness of panitumumab monotherapy and cetuximab (mono- or combination chemotherapy) for Kirsten rat sarcoma (KRAS) wild-type (WT) patients, and bevacizumab in combination with non-oxaliplatin chemotherapy, for the treatment of metastatic colorectal cancer after first-line chemotherapy.

DATA SOURCES

The assessment comprises a systematic review of clinical effectiveness and cost-effectiveness studies, a review and critique of manufacturer submissions and a de novo cohort-based economic analysis. For the assessment of effectiveness, a literature search was conducted in a range of electronic databases, including MEDLINE, EMBASE and The Cochrane Library, from 2005 to November 2010.

REVIEW METHODS

Studies were included if they were randomised controlled trials (RCTs) or systematic reviews of RCTs of cetuximab, bevacizumab or panitumumab in participants with EGFR-expressing metastatic colorectal cancer with KRAS WT status that has progressed after first-line chemotherapy (for cetuximab and panitumumab) or participants with metastatic colorectal cancer that has progressed after first-line chemotherapy (bevacizumab). All steps in the review were performed by one reviewer and checked independently by a second. Synthesis was mainly narrative. An economic model was developed focusing on third-line and subsequent lines of treatment. Costs and benefits were discounted at 3.5% per annum. Probabilistic and univariate deterministic sensitivity analyses were performed.

RESULTS

The searches identified 7745 titles and abstracts. Two clinical trials (reported in 12 papers) were included. No data were available for bevacizumab in combination with non-oxaliplatin-based chemotherapy in previously treated patients. Neither of the included studies had KRAS status performed prospectively, but the studies did report retrospective analyses of the results for the KRAS WT subgroups. Third-line treatment with cetuximab plus best supportive care or panitumumab plus best supportive care appears to have statistically significant advantages over treatment with best supportive care alone in patients with KRAS WT status. For the economic evaluation, five studies met the inclusion criteria. The base-case incremental cost-effectiveness ratio (ICER) for KRAS WT patients for cetuximab compared with best supportive care is £98,000 per quality-adjusted life-year (QALY), for panitumumab compared with best supportive care is £150,000 per QALY and for cetuximab plus irinotecan compared with best supportive care is £88,000 per QALY. All ICERs are sensitive to treatment duration.

LIMITATIONS

In the specific populations of interest, there is a lack of evidence on bevacizumab, cetuximab and cetuximab plus irinotecan used second line and on bevacizumab and cetuximab plus irinotecan used third line. For cetuximab plus irinotecan treatment for KRAS WT people, there is no direct evidence on progression-free survival, overall survival and duration of treatment.

CONCLUSIONS

Although cetuximab and panitumumab appear to be clinically beneficial for KRAS WT patients compared with best supportive care, they are likely to represent poor value for money when judged by cost-effectiveness criteria currently used in the UK. It would be useful to conduct a RCT for patients with KRAS WT status receiving cetuximab plus irinotecan.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Sunitinib for the treatment of gastrointestinal stromal tumours: a critique of the submission from Pfizer

The submission's evidence for the clinical effectiveness and cost-effectiveness of sunitinib for the treatment of gastrointestinal stromal tumours (GISTs) is based on a randomised controlled trial (RCT) comparing sunitinib with placebo for people with unresectable and/or metastatic GIST after failure of imatinib and with Eastern Cooperative Oncology Group (ECOG) progression status 0-1, and an ongoing, non-comparative cohort study of a similar population but with ECOG progression status 0-4. The searches are appropriate and include all relevant studies and the RCT is of high quality. In the RCT sunitinib arm overall survival was 73 median weeks [95% confidence interval (CI) 61 to 83] versus 75 median weeks (95% CI 68 to 84) for the cohort study. However, time to tumour progression in the cohort study was different from that in the RCT sunitinib arm [41 (95% CI 36 to 47) versus 29 (95% CI 22 to 41) median weeks respectively]. Median progression-free survival with sunitinib was 24.6 weeks (95% CI 12.1 to 28.4) versus 6.4 weeks (95% CI 4.4 to 10.0) on placebo (hazard ratio 0.333, 95% CI 0.238 to 0.467, p < 0.001). The manufacturer used a three-state Markov model to model the cost-effectiveness of sunitinib compared with best supportive care for GIST patients; the modelling approach and sources and justification of estimates are reasonable. The base-case incremental cost-effectiveness ratio (ICER) was 27,365 pounds per quality-adjusted life-year (QALY) with the first cycle of sunitinib treatment not costed; when we included the cost of the first treatment cycle we estimated a base-case ICER of 32,636 pounds per QALY. Pfizer's sensitivity analysis produced a range of ICERs from 15,536 pounds per QALY to 59,002 pounds per QALY. Weaknesses of the manufacturer's submission include that the evidence is based on only one published RCT; that 84% of the RCT control population crossed over to the intervention group, giving rise to the use of unusual rank preserved structural failure time (RPSFT) analysis to correct for possible bias; and that a number of errors and omissions were made in the probabilistic sensitivity analysis, meaning that it is not possible to come to firm conclusions about the cost-effectiveness of sunitinib for GIST in this patient population. In conclusion, during the blinded phase of the RCT, overall survival was significantly longer in the sunitinib arm than in the placebo arm (hazard ratio 0.491, 95% CI 0.290 to 0.831, p <0.007). However, intention-to-treat analysis of the entire study showed no statistically significant difference in overall survival for those who received sunitinib (73 weeks) versus those who received placebo (65 weeks) (hazard ratio 0.876, 95% CI 0.679 to 1.129, p = 0.306).

Sunitinib for the treatment of gastrointestinal stromal tumours: a critique of the submission from Pfizer

The submission’s evidence for the clinical effectiveness and cost-effectiveness of sunitinib for the treatment of gastrointestinal stromal tumours (GISTs) is based on a randomised controlled trial (RCT) comparing sunitinib with placebo for people with unresectable and/or metastatic GIST after failure of imatinib and with Eastern Cooperative Oncology Group (ECOG) progression status 0–1, and an ongoing, non-comparative cohort study of a similar population but with ECOG progression status 0–4. The searches are appropriate and include all relevant studies and the RCT is of high quality. In the RCT sunitinib arm overall survival was 73 median weeks [95% confidence interval (CI) 61 to 83] versus 75 median weeks (95% CI 68 to 84) for the cohort study. However, time to tumour progression in the cohort study was different from that in the RCT sunitinib arm [41 (95% CI 36 to 47) versus 29 (95% CI 22 to 41) median weeks respectively]. Median progression-free survival with sunitinib was 24.6 weeks (95% CI 12.1 to 28.4) versus 6.4 weeks (95% CI 4.4 to 10.0) on placebo (hazard ratio 0.333, 95% CI 0.238 to 0.467, p < 0.001). The manufacturer used a three-state Markov model to model the cost-effectiveness of sunitinib compared with best supportive care for GIST patients; the modelling approach and sources and justification of estimates are reasonable. The base-case incremental cost-effectiveness ratio (ICER) was £27,365 per quality-adjusted life-year (QALY) with the first cycle of sunitinib treatment not costed; when we included the cost of the first treatment cycle we estimated a base-case ICER of £32,636 per QALY. Pfizer’s sensitivity analysis produced a range of ICERs from £15,536 per QALY to £59,002 per QALY. Weaknesses of the manufacturer’s submission include that the evidence is based on only one published RCT; that 84% of the RCT control population crossed over to the intervention group, giving rise to the use of unusual rank preserved structural failure time (RPSFT) analysis to correct for possible bias; and that a number of errors and omissions were made in the probabilistic sensitivity analysis, meaning that it is not possible to come to firm conclusions about the cost-effectiveness of sunitinib for GIST in this patient population. In conclusion, during the blinded phase of the RCT, overall survival was significantly longer in the sunitinib arm than in the placebo arm (hazard ratio 0.491, 95% CI 0.290 to 0.831, p <0.007). However, intention-to-treat analysis of the entire study showed no statistically significant difference in overall survival for those who received sunitinib (73 weeks) versus those who received placebo (65 weeks) (hazard ratio 0.876, 95% CI 0.679 to 1.129, p = 0.306).

Use of physician assistants as surgery/trauma house staff at an American College of Surgeons-verified Level II trauma center

BACKGROUND

Historically, surgical physicians staff trauma centers, which provide trauma patients with improved outcomes. Such benefits fuel the expansion of designated trauma centers. Cutbacks in residency programs of surgical specialties, however, necessitate substitutions for traditional trauma providers.

METHODS

A literature and record review was conducted to examine the use of physician assistants in a large community hospital's verified trauma center. Current and historical outcomes were analyzed regarding the trauma surgeon/physician assistant model.

RESULTS

Injury Severity Scores increased 19%, transfer time to the operating room decreased 43%, transfer time to the intensive care unit decreased 51%, and transfer time to the floor decreased 20%. The length of stay for admissions decreased 13%, and the length of stay for neurotrauma intensive care unit patients decreased 33%.

CONCLUSION

The Hurley Medical Center trauma surgeon/physician assistant model is a viable alternative for verified trauma centers unable to maintain a surgical residency program. Consistency and quality of care indicated by shortened length of stay is a hallmark of such a model providing the highest quality of care.

Nonpsychotic thought disorder: objective clinical identification of somatization and antisocial personality in language patterns

This report describes a new method of using language patterns to identify somatization and antisocial personality (ASPD) disorders in clinical practice. A set of definitions describing characteristic speech patterns was developed to identify "nonpsychotic thought disorder" (NPTD). Speech patterns of subjects with somatization disorder and/or ASPD were compared with those of controls. Blind raters assessed audiotaped samples of speech obtained through open-ended interviews for instances of elements of NPTD. Women with somatization or ASPD had significantly more NPTD speech responses than controls, and women with both disorders showed the greatest amount. Antisocial men did not demonstrate more NPTD than controls, nor was somatization in men associated with NPTD. Clinical attention to speech patterns in patients may help alert clinicians to these disorders in women and serve as indicators for screening for these disorders. More study is needed to develop psychometric properties of the instruments on larger samples, and to identify speech indicators of personality disorder in men. It is likely that other personality disorders, e.g., borderline personality disorder, can be identified through speech patterns, and they deserve study with these methods.

Antibody-directed enzyme prodrug therapy: pharmacokinetics and plasma levels of prodrug and drug in a phase I clinical trial

Antibody-directed enzyme prodrug therapy (ADEPT) was administered to ten patients in a phase I clinical trial. The aim was to measure plasma levels of the prodrug 4-[(2-chloroethyl)(2-mesyloxyethyl) amino] benzoyl-L-glutamic acid (CMDA) and the bifunctional alkylating drug (CJS11) released from it by the action of tumour-localised carboxypeptidase G2 (CPG2) enzyme. New techniques were developed to extract the prodrug and drug from plasma by solid-phase absorption and elution and to measure CPG2 activity in plasma and tissue. All extracts were analysed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). CPG2 activity was found in metastatic tumour biopsies but not in normal tissue, indicating that localisation had been successful. The clearing agent SB43-gal, given at 46.5 mg/m2, achieved the aim of clearing non-tumour-localised enzyme in the circulation, indicating that conversion of prodrug to drug could take place only at the site of localised conjugate. Plasma prodrug did not always remain above its required threshold of 3 microM for the "therapeutic window" of 120 min after dosing, but the presence of residual prodrug after the first administration of each day indicated that this could be achieved during the remaining four doses over the following 8 h. Despite considerable inter-patient prodrug plasma concentration variability, the elimination half-life of the prodrug was remarkably reproducible at 18 +/- 8 min. Rapid appearance of the drug in plasma indicated that successful conversion from the prodrug had taken place, but also undesirable leakback from the site of localisation into the bloodstream. However, drug plasma levels fell rapidly by at least 50% at between 10 and 60 min with a half-life of 36 +/- 14 min. Analysis of the plasma extracts by LC/MS indicated that this technique might be used to confirm qualitatively the presence of prodrug, drug and their metabolites.

Complaints of constipation in obsessive-compulsive disorder

Psychoanalytic observation has launched a long tradition in medical literature that links constipation with obsessive-compulsive traits. This association, however, has never been tested empirically. The current investigation sought to test this hypothesized association empirically using a large, randomly sampled population database. Data from the Epidemiologic Catchment Area project collected with the Diagnostic Interview Schedule were analyzed to determine the association, if any, of complaint of medically unexplained constipation (ascertained from the somatization disorder section of the interview) with a DIS diagnosis of obsessive compulsive disorder (OCD). Reported history of constipation was significantly associated with a lifetime diagnosis of OCD in women (not men), even when controlling for symptom-reporting biases using number of other positive somatoform symptoms. This association was specific to constipation and OCD and did not apply to other functional bowel symptoms including diarrhea, bloating (gas), and abdominal pain. Other psychiatric disorders commonly implicated with functional bowel complaints--major depression and panic disorder--were not significantly associated with constipation controlling for effects of other somatoform symptoms. The lack of association of constipation with OCD in men in a general population sample fails to support psychoanalytic concepts that historically have linked these two phenomena, but a special relationship of OCD with constipation was present in women.

RGD-containing peptides inhibit adhesion of 293 cells transfected with GpIIb/IIIa to fibrinogen: comparison to inhibition of platelet aggregation

Cyclic RGD-containing peptides caused a dose-dependent inhibition of binding of human embryonic kidney cells transfected with recombinant GpIIb/IIIa (r293 clone B) to human fibrinogen coated on to non-tissue culture plates. The inhibitory activity, IC50, of a panel of seventeen RGD-containing peptides ranged from 0.12 to 89.2 microM. These IC50 values correlated with those determined by the inhibition of platelet aggregation (r = 0.99). Even though there was a correlation, there were differences between the platelet aggregation and the bioadhesion assay. The binding of r293 clone B to fibrinogen was not increased by ADP suggesting that GpIIb/IIIa expressed on the surface of r293 clone B cells may be in the 'activated' form. Moreover, preincubation of r293 clone B cells with a monoclonal antibody (mAb) specific for GpIIIa (4B12) resulted in a dose-dependent decrease of binding to fibrinogen while a mAb specific for GPIIb (2D2) had no effect. Neither of these mAbs inhibited platelet aggregation. The binding of r293 clone B cells to fibrinogen required Ca2+ or Mg2+. This cell-based bioadhesion method can provide a tool for screening potential GpIIb/IIIa antagonists and investigating the interaction of GpIIb/IIIa and fibrinogen not possible with platelet aggregation.

Pneumothorax as a complication of tumour response to chemotherapy

A patient with extensive pulmonary involvement by disseminated adenocarcinoma is presented. Response to chemotherapy resulted in the direct rupture of necrotic tumour tissue into the pleural cavity leading to a pneumothorax. The condition failed to improve with chest drainage and suction, necessitating surgical intervention. The development of the pneumothorax proved to be a fatal complication of treatment.

G4120, an Arg-Gly-Asp containing pentapeptide, enhances arterial eversion graft recanalization with recombinant tissue-type plasminogen activator in dogs

The effects of G4120, a cyclic Arg-Gly-Asp (RGD) containing peptide which inhibits fibrinogen binding to the platelet receptor GPIIb/IIIa, on thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) were investigated in a combined arterial and venous thrombosis model in heparinized dogs. The arterial thrombus model consisted of a 3 cm everted (inside-out) carotid arterial segment inserted into a transsected femoral artery which occludes within 30 min with platelet-rich material and which is resistant to recanalization with 0.5 mg/kg rt-PA. The venous thrombus was a 125I-fibrin labeled whole blood clot produced in the contralateral femoral vein. In 5 dogs given an intravenous bolus of 0.05 mg/kg G4120 followed by a continuous infusion of 0.05 mg/kg per hour for 3 h (group I), arterial occlusion persisted throughout a 4 h observation period and was still present at 24 h in all dogs; the extent of venous clot lysis after 120 min was 27 +/- 7%. In 5 dogs given the same infusion of G4120 in combination with 0.5 mg/kg rt-PA over 60 min, recanalization of the arterial graft occurred in all dogs, within 13 +/- 2 min and persisted throughout the observation period of 4 h (p = 0.01 versus G4120 or rt-PA alone); at 24 h, however, all grafts were occluded. Venous clot lysis in this group was 75 +/- 8% (p = 0.002 versus G4120 alone and p = NS versus rt-PA alone). Pathologic analysis revealed platelet-rich or mixed thrombus with platelet-rich and erythrocyte-rich zones.(ABSTRACT TRUNCATED AT 250 WORDS)

Transmembrane TGF-alpha precursors activate EGF/TGF-alpha receptors

TGF-alpha and EGF are structurally related factors that bind to and induce tyrosine autophosphorylation of a common receptor. Proteolytic cleavage of the transmembrane TGF-alpha precursor's external domain releases several TGF-alpha species. However, membrane-bound TGF-alpha forms remain on the surface of TGF-alpha-expressing cell lines. To evaluate the biological activity of these forms, we modified two cleavage sites in the TGF-alpha precursor coding sequence, making processing into the 50 amino acid TGF-alpha impossible. Overexpression of this cDNA in a receptor-negative cell line, partial purification, and N-terminal sequence analysis indicate the existence of two transmembrane TGF-alpha forms. These solubilized precursors induce tyrosine autophosphorylation of the EGF/TGF-alpha receptor in intact receptor-overexpressing cells, and anchorage-independent growth of NRK fibroblasts. Cell-cell contact between TGF-alpha precursor-overexpressing cells and cells expressing high numbers of receptors also resulted in receptor activation. These findings suggest a role for transmembrane TGF-alpha forms in intercellular interactions in proliferating tissues.

Properties of a human insulin receptor with a COOH-terminal truncation. II. Truncated receptors have normal kinase activity but are defective in signaling metabolic effects

We have previously shown that a mutant human insulin receptor with a COOH-terminal 43-amino acid deletion (HIR delta CT), when expressed in Rat 1 fibroblasts, binds insulin normally, autophosphorylates, and undergoes endocytosis after insulin binding in a manner comparable to the normal human insulin receptor (HIRc). In this paper we have examined the biologic activity of the truncated and normal insulin receptors. In vitro, the HIR delta CT receptors caused a 1.8-fold greater phosphorylation of a Glu4/Tyr1 polypeptide than did the HIRc receptors, but the two receptor types were nearly equivalent in their ability to phosphorylate a src-derived peptide. Furthermore, insulin preactivation of HIRc and HIR delta CT receptors in intact cells led to equivalent stimulation of tyrosine kinase activity as subsequently determined for histone in vitro. Expression of HIRc receptors in cells led to enhanced sensitivity to insulin of 2-deoxy-D-glucose uptake and glycogen synthase activation. This increased sensitivity was proportional to receptor number at low (Ro = 6400) but not at high (Ro = 1.25 X 10(6] levels of receptor expression. However, expression of HIR delta CT receptors (Ro = 2.5 X 10(5] led to little, if any, increase in insulin sensitivity of either 2-deoxy-D-glucose uptake or glycogen synthase activation. Furthermore, compared with HIRc cells, HIR delta CT cells respond poorly to an agonistic monoclonal antibody specific for the human insulin receptor. In conclusion, the HIR delta CT receptor retains intact protein kinase activity in vitro. Despite this, however, the receptor displays low activity in mediating the metabolic effects of insulin.