Site-selective modification strategies in antibody-drug conjugates

Antibody-drug conjugates (ADCs) harness the highly specific targeting capabilities of an antibody to deliver a cytotoxic payload to specific cell types. They have garnered widespread interest in drug discovery, particularly in oncology, as discrimination between healthy and malignant tissues or cells can be achieved. Nine ADCs have received approval from the US Food and Drug Administration and more than 80 others are currently undergoing clinical investigations for a range of solid tumours and haematological malignancies. Extensive research over the past decade has highlighted the critical nature of the linkage strategy adopted to attach the payload to the antibody. Whilst early generation ADCs were primarily synthesised as heterogeneous mixtures, these were found to have sub-optimal pharmacokinetics, stability, tolerability and/or efficacy. Efforts have now shifted towards generating homogeneous constructs with precise drug loading and predetermined, controlled sites of attachment. Homogeneous ADCs have repeatedly demonstrated superior overall pharmacological profiles compared to their heterogeneous counterparts. A wide range of methods have been developed in the pursuit of homogeneity, comprising chemical or enzymatic methods or a combination thereof to afford precise modification of specific amino acid or sugar residues. In this review, we discuss advances in chemical and enzymatic methods for site-specific antibody modification that result in the generation of homogeneous ADCs.

Early infection after hip fracture surgery: risk factors, costs and outcome

Prospective data on hip fracture from 3686 patients at a United Kingdom teaching hospital were analysed to investigate the risk factors, financial costs and outcomes associated with deep or superficial wound infections after hip fracture surgery. In 1.2% (41) of patients a deep wound infection developed, and 1.1% (39) had a superficial wound infection. A total of 57 of 80 infections (71.3%) were due to Staphylococcus aureus and 39 (48.8%) were due to MRSA. No statistically significant pre-operative risk factors were detected. Length of stay, cost of treatment and pre-discharge mortality all significantly increased with deep wound infection. The one-year mortality was 30%, and this increased to 50% in those who developed an infection (p < 0.001). A deep infection resulted in doubled operative costs, tripled investigation costs and quadrupled ward costs. MRSA infection increased costs, length of stay, and pre-discharge mortality compared with non-MRSA infection.

Synthesis and Evaluation of 1,8-Disubstituted-Cyclam/Naphthalimide Conjugates as Probes for Metal Ions

Fluorescent molecular probes for metal ions have a raft of potential applications in chemistry and biomedicine. We report the synthesis and photophysical characterisation of 1,8‐disubstituted‐cyclam/naphthalimide conjugates and their zinc complexes. An efficient synthesis of 1,8‐bis‐(2‐azidoethyl)cyclam has been developed and used to prepare 1,8‐disubstituted triazolyl‐cyclam systems, in which the pendant group is connected to triazole C4. UV/Vis and fluorescence emission spectra, zinc binding experiments, fluorescence quantum yield and lifetime measurements and pH titrations of the resultant bis‐naphthalimide ligand elucidate a complex pattern of photophysical behaviour. Important differences arise from the inclusion of two fluorophores in the one probe and from the variation of triazole substitution pattern (dye at C4 vs. N1). Introducing a second fluorophore greatly extends fluorescence lifetimes, whereas the altered substitution pattern at the cyclam amines exerts a major influence on fluorescence output and metal binding. Crystal structures of two key zinc complexes evidence variations in triazole coordination that mirror the solution‐phase behaviour of these systems.

Cilostazol and peripheral arterial disease

Peripheral arterial disease is both common and disabling. Contemporary management of peripheral arterial disease is multimodal, encompassing both medical and interventional treatments. Cilostazol (Pletal), a 2-oxoquinolone derivative, is currently licensed in the UK for the treatment of patients with intermittent claudication to improve their walking distance in the absence of tissue necrosis or rest pain. The therapeutic effects of cilostazol are thought to be mediated through antiplatelet, antiproliferative and vasodilatory activities. This review aims to provide an overview of the management of peripheral arterial disease focusing upon cilostazol pharmacotherapy.

Efficient and selective antibody modification with functionalised divinyltriazines

We have developed a highly efficient disulfide rebridging strategy for the modification of antibodies with substituted divinyltriazine linkers.

Carotid stenting for restenosis after endarterectomy

INTRODUCTION

Restenosis after carotid endarterectomy (CEA) has been described in 8-19% of patients, 14-23% of whom become symptomatic. This study analyzes our experience with carotid artery stenting (CAS) for post-CEA recurrent stenoses.

METHOD

Retrospective database and case-note review.

RESULTS

Between January 2000 and September 2008, a total of 27 patients (15 symptomatic) with hemodynamically significant internal carotid artery post-CEA restenosis underwent CAS. Median stenosis of target vessels was 90% (range 75-95%). There was one periprocedural death (3.7%); no others occurred during the median 34-month follow-up (range 0.1-84 months). There was one late transient ischemic attack 12 months after CAS that was not associated with in-stent restenosis. One 90% restenosis and one occlusion were detected during follow-up at 38 and 57 months after CAS. The remaining patients had no evidence of further restenosis and remained free from cerebrovascular symptoms.

CONCLUSION

CAS offers a feasible option for the management of carefully selected patients with symptomatic and asymptomatic restenosis after CEA.

A direct method for the N-tetraalkylation of azamacrocycles

An efficient protocol for the direct synthesis of N-tetraalkylated derivatives of the azamacrocycles cyclam and cyclen has been developed, using a partially miscible aqueous–organic solvent system with propargyl bromide, benzyl bromide, and related halides. The method works most effectively when the reaction mixture is shaken, not stirred. A crystal structure of the N-tetrapropargyl cyclam derivative 1,4,8,11-tetra(prop-2-yn-1-yl)-1,4,8,11-tetraazacyclotetradecane diperchlorate is reported.

Antibody dual-functionalisation enabled through a modular divinylpyrimidine disulfide rebridging strategy

Herein we report the development of a methodology for the dual-functionalisation of IgG antibodies. This is accomplished through the combination of disulfide rebridging divinylpyrimidine technology, with bicyclononyne and methylcyclopropene handles to facilitate sequential SPAAC and IEDDA reactions. Advantageously, the strategy does not require metal catalysis and avoids the need for purification between functionalisation steps.

A retrospective, observational study of supine percutaneous nephrolithotomy

Objective:

The objective of this study is to assess stone clearance and perioperative complication rates of supine percutaneous nephrolithotomy (PCNL).

Methods:

This was a retrospective, observational study of supine PCNL performed in a surgical unit at a district general hospital by two surgeons in the United Kingdom. Data collected included patient demographics, comorbidities, complexity of renal calculi, perioperative complications and stone clearance rates.

Results:

A total of 112 supine PCNL procedures were observed in this study. The mean (SD) American Society of Anesthesiologists (ASA) grade and Guy’s Stone Score were 2.0 (0.75) and 2.3 (1.06) respectively. The median (interquartile range (IQR)) duration of in-patient admission was four (one) nights. Complete stone clearance was achieved in 74 (67.3%) of the procedures, while more than 90% clearance of the renal stone burden was achieved in a further eight (7.3%). The most common perioperative complications recorded were blood loss requiring blood transfusion (three (2.7%)) and postoperative fever (two (1.8%)).

Conclusion:

This case series shows that supine PCNL can lead to good stone clearance and low complication rates.

‘Adrenal incidentalomas’; Rationalising assessment in the urology multi-disciplinary team meeting

The combination of an aging population and the continual technological advances in modern imaging techniques have contributed to the increased detection of asymptomatic incidental lesions. The definition of an adrenal ‘incidentaloma’ is an asymptomatic lesion (⩾1 cm) detected on imaging following a suspected alternative primary diagnosis. The majority of these adrenal incidentalomas, may be benign and non-functioning, however, a proportion of these lesions may be either malignant or ‘hyperfunctioning’ (hormone-producing). As such, these incidental and asymptomatic lesions can provide the urologist with a diagnostic dilemma. In this article we aim to review the current literature with reference to common clinical scenarios often encountered as part of the urology multi-disciplinary team meeting. The overall aim is to rationalise and standardise an approach to these often challenging scenarios.

A groin mass caused by metal particle debris after hip resurfacing

We present the case of a benign groin mass associated with metal particle debris after hip resurfacing. We discuss the histological diagnosis of 'aseptic lymphocytic vasculitis associated lesions' (ALVAL).

The Checklist of Unit Behaviours (CUB): Validation within a Canadian outpatient day hospital programme

WHAT IS KNOWN ON THE SUBJECT?: The psychometrics of the CUB measure have been tested within an inpatient psychiatric setting. Results show that the CUB has two factors that reflect patients' approach and avoidance of dimensions of the treatment milieu, and that an increase of approach and decrease of avoidance are correlated with discharge. No empirical research has examined the validity of the CUB in a day hospital programme. WHAT THIS ARTICLE ADDS TO EXISTING KNOWLEDGE?: This study was the first to address the validity of this questionnaire within a psychiatric day hospital setting. This now allows other mental health service providers to use this questionnaire following administration of patient engagement interventions (such as behavioural activation), which are routinely used within this type of a setting. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Our results can enable healthcare providers to employ an effective and psychometrically validated tool in a day hospital setting to measure treatment outcomes and provide reflections of patients' approach behaviours and avoidance behaviours.

ABSTRACT

Introduction We evaluated the Checklist of Unit Behaviours (CUBs) questionnaire in a novel mental health setting: a day hospital within a large acute care general hospital. No empirical evidence exists, as of yet, to look at the validity of this measure in this type of a treatment setting. The CUB measures two factors, avoidance or approach, of the patients' engagement with the treatment milieu within the previous 24 hr. Aim A confirmatory factor analysis (CFA) was conducted to validate the CUB's original two factor structure in an outpatient day programme. Methods Psychiatric outpatients (n = 163) completed the CUB daily while participating in a day hospital programme in Toronto, Canada. Results A CFA was used to confirm the CUB factors but resulted in a poor fitting model for our sample, χ² (103) = 278.59, p < .001, CFI = 0.80, RMSEA = 0.10, SRMR = 0.10. Questions 5, 8 and 10 had higher loadings on a third factor revealed through exploratory factor analysis. We believe this factor, "Group Engagement," reflects the construct of group-related issues. Discussion The CUB was a practical and useful tool in our psychiatric day hospital setting at a large acute care general hospital. Implications for practice Our analysis identified group engagement, a critical variable in day programmes, as patients have autonomy regarding staying or leaving the programme.

Copper(ii) complexes of N-propargyl cyclam ligands reveal a range of coordination modes and colours, and unexpected reactivity

The coordination chemistry of N-functionalised cyclam ligands has a rich history, yet cyclam derivatives with pendant alkynes are largely unexplored. This is despite the significant potential and burgeoning application of N-propargyl cyclams and related compounds in the creation of diversely functionalised cyclam derivatives via copper-catalysed azide-alkyne 'click' reactions. Herein we describe single crystal X-ray diffraction and spectroscopic investigations of the coordination chemistry of copper(ii) complexes of cyclam derivatives with between 1 and 4 pendant alkynes. The crystal structures of these copper complexes unexpectedly reveal a range of coordination modes, and the surprising occurrence of five unique complexes within a single recrystallisation of the tetra-N-propargyl cyclam ligand. One of these species exhibits weak intramolecular copper-alkyne coordination, and another is formed by a surprising intramolecular copper-mediated hydroalkoxylation reaction with the solvent methanol, transforming one of the pendant alkynes to an enol ether. Multiple functionalisation of the tetra-N-propargyl ligand is demonstrated via a 'tetra-click' reaction with benzyl azide, and the copper-binding behaviour of the resulting tetra-triazole ligand is characterised spectroscopically.