A Proximity Extension Assay (PEA)-based method for quantification of bevacizumab.

INTRODUCTION: Proximity Extension Assay (PEA) is a direct one-step protein quantification method using a pair of DNA oligonucleotides linked to antibodies against the target molecule. It requires polyclonal or two monoclonal antibodies (mAbs) that bind to target epitopes close enough to form a DNA duplex which is quantified by real-time PCR. Bevacizumab, an anti-cancer drug, is a mAb against vascular endothelial growth factor with common cardiovascular adverse effects. It is widely used off-label to treat neovascular eye disorders by intravitreal application of small doses. Even then, certain amount reaches systemic circulation which is considered relevant regarding safety. We aimed to set-up a PEA-based assay for bevacizumab in human plasma and to preliminary evaluate it in patients treated intravitreally. METHODS: We tested (PEA, quantitative PCR) several combinations of commercial mAbs and a Fab fragment against bevacizumab. The best combination was used to quantify bevacizumab in three patients donating plasma before and 24 h after the first intravitreal injection. RESULTS: A combination of a mAb and a Fab fragment (HCA184 and HCA182, Bio-Rad Laboratories, Inc.) performed best: standard curve R2 0.98, linear dynamic range 1-1000 pM, lower limit of quantification 1 pM (149 pg/mL) and a satisfactory precision (coefficient of variation 12%). All pre-dose patient concentrations were zero, while post-dose concentrations were 10.94, 13.73 and 55.49 ng/mL, in line with previous reports. DISCUSSION: This is the first set-up of a PEA-based assay for quantification of bevacizumab in human plasma. Its good performance and high sensitivity support further evaluation for potential uses particularly when the expected concentrations are low.

Intravitreal Bevacizumab and Cardiovascular Risk in Patients with Age-Related Macular Degeneration: Systematic Review and Meta-Analysis of Randomized Controlled Trials and Observational Studies.

INTRODUCTION: Intravitreal bevacizumab (IVTB) is used to treat age-related macular degeneration (ARMD), although its use is off-label and its cardiovascular safety has not been unequivocally established. OBJECTIVES: Our objective was to assess the cardiovascular safety of IVTB in patients with ARMD. METHODS: We conducted a systematic review and meta-analysis of published randomized controlled trials (RCTs) and observational studies. RESULTS: Of the 2028 non-duplicate records, five RCTs versus ranibizumab (N = 3038, 12/24 months), four RCTs comparing different regimens (N = 809, 12/23 months), one RCT versus pegaptanib, photodynamic therapy (PDT), or sham (N = 131, 12 months), and three observational studies versus PDT, ranibizumab, or pegaptanib (~150,000 or 1666 patients/12 months and 317 patients/1-2 years, respectively) had a low risk of bias/high quality and ≥20 patients per arm with ≥6 months and ≥3 injections of treatment. RCT-based comparisons with PDT or pegaptanib are negligible. Observational data have not demonstrated differences [all-cause mortality, myocardial infarction (MI), stroke], but the level of evidence is "very low" (imprecise, indirect). RCT-based comparisons with ranibizumab did not demonstrate differences regarding some outcomes, although certain point estimates were at the level of a relevant harm/benefit [all-cause mortality odds ratio (OR) 1.103, 95 % confidence interval (CI) 0.641-1.898; vascular mortality OR 1.380, 95 % CI 0.476-3.997; MI OR 0.551, 95 % CI 0.265-1.146; stroke OR 0.657, 95 % CI 0.260-1.660; transitory ischemic attack OR 1.536, 95 % CI 0.444-5.313; atherothrombotic events (ATEs) OR 1.007, 95 % CI 0.641-1.593; venous thromboembolism OR 2.325, 95 % CI 0.963-5.612] or suggested a higher risk with bevacizumab (hypertension OR 7.512, 95 % CI 1.056-52.3), but estimates were based on sparse data, were extremely imprecise, and commonly exhibited considerable heterogeneity/inconsistency. The level of evidence per outcome was "low" or "very low". Observational data did not demonstrate difference (all-cause mortality, MI, stroke), or suggested a higher risk with bevacizumab (ATE), but were imprecise and indirect (level of evidence "very low"). RCT-based comparisons of different IVTB regimens suffered from the same limitations. CONCLUSION: Published data on IVTB in AMRD provide only a low level of evidence on its cardiovascular safety and do not support any finite conclusions.

[A report of rarely observed resistance pattern to carbapenems in a clinical isolate of Enterobacter cloacae]. / Prikaz rijetko videnog oblika otpornosti na karbapeneme u vrste Enterobacter cloacae.

The paper reports on the emergence of strain in which Enterobacter cloacae has demonstrated an unusual form of resistance to carbapenems mediated by enzyme IMI-1, class A beta-lactamase. The strain was isolated from a wound swab in the patient who had a surgical wound infection previously treated with meropenem. Limited choice of antibiotics that can treat infections caused by these pathogens indicates the necessity of accurate identification of multiple resistant gram-negative microorganisms and mechanisms of their resistance. Recognition of multiresistant gram-negative microorganisms emphasizes the importance of continuous microbiological monitoring of patients, especially in intensive care units. In the investigated institution there was no secondary spread of this strain. Identifying new mechanisms of resistance will be helpful to clinicians in selection of targeted therapy, while important for efficient prevention of spreading infections caused by multiple resistant microorganisms.