PET study of ocular and blood pharmacokinetics of intravitreal bevacizumab and aflibercept in rats.

Intravitreal injections are the standard procedure in the treatment of retinal pathologies, such as the administration of the anti-VEGF antibodies in age-related macular degeneration. The aim of this study is to evaluate the intraocular and blood pharmacokinetics after an intravitreal injection of 89Zr-labelled bevacizumab and 89Zr-labelled aflibercept in Sprague-Dawley rats using Positron Emission Tomography. First, both antibodies were radiolabelled to zirconium-89 with a maximum specific activity of 15 Mbq/mg for bevacizumab and 10 Mbq/mg for aflibercept. Four µL containing 1-1.2 Mq of 89Zr-labelled compound were injected into the vitreous through a 35 G needle. A microPET acquisition was carried out immediately after the injection and at different time points through a 12-day study and blood samples were obtained through the tail vein. Radiolabelling was successfully performed with a radiochemical purity after ultrafiltration above 95% for both agents. Both antibodies ocular curves followed a two-compartment model in which an intraocular elimination half-life of 16.44 h was found for 89Zr-bevacizumab and 4.51 h for 89Zr-aflibercept, considering the alpha phase as the elimination phase. Regarding the beta phase, a half-life of 3.23 days for 89Zr-bevacizumab and 4.69 days for 89Zr-aflibercept were observed. With regards to blood concentration, 89Zr-bevacizumab showed a blood half-life of 7.08 days, whereas 89Zr-aflibercept's was 3.18 days, by a one-compartment model with first-order absorption kinetics. In conclusion, this study shows for the first time the ocular and blood pharmacokinetic analysis after intravitreal injection of aflibercept and bevacizumab in rats.

Comparison of Bevacizumab Quantification Results in Plasma of Non-small Cell Lung Cancer Patients Using Bioanalytical Techniques Between LC-MS/MS, ELISA, and Microfluidic-based Immunoassay.

The development of analytical techniques to study therapeutic monoclonal antibodies is expected to be useful for pharmacokinetic analysis and for the development of therapeutic indexes to determine dosage standards. To date, the blood concentration of antibody drugs has been analyzed by the enzyme-linked immunosorbent assay (ELISA). However, with the development of mass spectrometry and microfluidization technologies, the assay implication is drastically changing. We have developed an analytical validation method for many monoclonal antibodies and Fc-fusion proteins using Fab-selective proteolysis nSMOL coupled with liquid chromatography-mass spectrometry (LC-MS/MS). However, the correlation between the analyzed data characterization and the referable value from individual measurement techniques has not been adequately discussed. Therefore, in this study, we discussed in detail the relationship of the bioanalytical data from three different techniques, LC-MS/MS, ELISA, and microfluidic immunoassay, using 245 clinical plasma samples from non-small cell lung cancer patients treated with bevacizumab. The quantified concentration data of bevacizumab in human plasma indicated that the results obtained were almost the same correlation regardless of which technique was used. And the referable value from LC-MS/MS and microfluidic immunoassay were similar and correlated compared with ELISA.

Production of monoclonal antibodies for measuring Avastin and its biosimilar by Sandwich ELISA.

The development of Bevacizumab (Avastin) biosimilar products has grown rapidly over the last ten years as the original Avastin's patent will expire soon. The approval of Avastin biosimilars requires the demonstration of similarity between the biosimilar and the reference product. To support pre-clinical and clinical studies, pharmacokinetic (PK) assays are required to measure the biosimilar and Avastin with comparable precision and accuracy. The PK assay of Avastin employed by Genentech was a Sandwich ELISA which could detect the total drug concentration. However, it was developed in-house and not commercially available. Therefore, in most of the Avastin biosimilar pre-clinical studies, the antibody drug concentrations were measured using an indirect ELISA against coated VEGF, which could only measure the free instead of the total antibody drugs. It failed the essential requirement to develop the biosimilars. In this study, we reported the generation of mouse monoclonal antibodies (mAbs) that specifically recognize Avastin in a VEGF non-competitive manner. Using a pair of non-VEGF competing anti-Avastin mAbs, a Sandwich ELISA was developed with a lower limit of quantitation (LLOQ) at 400 ng/mL and upper limit of quantitation (ULOQ) at 12800 ng/mL. The assay validation was carried out with serum samples from monkey treated with Avastin biosimilar at seven different time points. Our data showed that the Sandwich ELISA kit we developed is sensitive, simple, reproducible and ready for use in human clinical trials.

A Randomized, Double-Blind Trial Comparing the Pharmacokinetics of CT-P16, a Candidate Bevacizumab Biosimilar, with its Reference Product in Healthy Adult Males.

BACKGROUND: CT-P16 is a candidate biosimilar of bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor that is used in the treatment of a range of advanced solid cancers. OBJECTIVE: The objective of this study was to demonstrate the pharmacokinetic equivalence of CT-P16 and European Union (EU)-approved bevacizumab (EU-bevacizumab) and US-licensed bevacizumab (US-bevacizumab) reference products. METHODS: In this double-blind, parallel-group phase I trial (ClinicalTrials.gov identifier NCT03247673), healthy adult males were randomized (1:1:1) to receive a single dose of CT-P16 5 mg/kg, EU-bevacizumab 5 mg/kg, or US-bevacizumab 5 mg/kg. Primary study endpoints were area under the concentration-time curve (AUC) from time zero to infinity (AUC∞), AUC from time zero to the last quantifiable concentration (AUClast), and maximum serum concentration (Cmax). Pharmacokinetic equivalence was shown if the 90% confidence intervals (CIs) of the geometric mean (GM) ratios of the AUC∞, AUClast, and Cmax were within the predefined bioequivalence margin of 80-125%. Safety and immunogenicity were also evaluated. RESULTS: A total of 144 subjects were randomized: 47 to CT-P16, 49 to EU-bevacizumab, and 48 to US-bevacizumab. The 90% CIs for the GM ratios of AUC∞, AUClast, and Cmax for CT-P16/EU-bevacizumab, CT-P16/US-bevacizumab, and EU-bevacizumab/US-bevacizumab comparisons were all within the bioequivalence margin. Mean serum concentration-time profiles, secondary pharmacokinetic parameters, and safety and immunogenicity profiles were comparable across all three treatment groups. CONCLUSION: CT-P16 demonstrated pharmacokinetic equivalence to EU-bevacizumab and US-bevacizumab. Safety and immunogenicity profiles were similar for CT-P16, EU-bevacizumab, and US-bevacizumab. These data support the further clinical evaluation of CT-P16 as a bevacizumab biosimilar. CLINICAL TRIALS REGISTRATION: NCT03247673.

Automated flow fluorescent noncompetitive immunoassay for measurement of human plasma levels of monoclonal antibodies used for immunotherapy of cancers with KinExA™ 3200 biosensor.

This study describes, for the first time, the development of an automated sensitive flow fluorescent noncompetitive immunoassay based on kinetic-exclusion analysis (KinExA) for the quantitative determination of human plasma levels of monoclonal antibodies (mAbs) used for cancer immunotherapy. The assay was adapted on KinExA™ 3200 biosensor and optimized and validated for bevacizumab (BEV) and cetuximab (CET), as representative examples of the mAbs, using their specific antigens. These antigens were the human vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) for BEV and CET, respectively. The limits of detection were 1.28 and 52.64 ng mL-1 for BEV and CET, respectively. The accuracy of the assay was demonstrated with analytical recovery of analytes from spiked plasma at 96.2-104.3 and 96.8-105.3% for BEV and CET, respectively. The precision of the assay was satisfactory as shown by relative standard deviation (RSD) at 2.2-5.7 and 2.5-6.1% for assay of BEV and CET, respectively. The high sensitivity of the assay allowed the use of very small volumes (~ 1 µL) of plasma sample for analysis. Automated analysis by the proposed KinExA-based assay facilitates the processing of large numbers of mAbs-containing specimens in studies of pharmacokinetics (PK), pharmacodynamics (PD), and therapeutic drug monitoring (TDM) of therapeutic mAbs. The proposed assay can be used to overcome the problems encountered in the existing conventional immunoassays for mAbs.

A randomized, single-blind, single-dose study to assess the pharmacokinetic equivalence of the biosimilar ABP 215 and bevacizumab in healthy Japanese male subjects.

PURPOSE: Analytic, pharmacokinetic (PK), and clinical similarity between the biosimilar ABP 215 and bevacizumab has previously been demonstrated in global studies. Here we present a phase 1 study in healthy adult Japanese men. METHODS: This study was a randomized, single-blind, single-dose, parallel-group study comparing PK parameters of ABP 215 versus EU-authorized bevacizumab in healthy Japanese men. Primary endpoints were maximum observed serum concentration (Cmax) and area under the serum concentration-time curve from time 0 to infinity (AUCinf). Secondary endpoints included AUC from time 0 to time of last quantifiable concentration (AUClast), safety, tolerability, and immunogenicity. RESULTS: Baseline characteristics were similar among study subjects (n = 24/group). After a 3-mg/kg intravenous infusion, the geometric means (GMs) of Cmax, AUCinf, and AUClast were 71.2 µg/mL, 25,259 µg h/mL, and 22,499.3 µg h/mL, respectively, for ABP 215 and 70.16 µg/mL, 25,801 µg h/mL, and 22,604.6 µg h/mL, respectively, for bevacizumab. The GM ratios (90% confidence interval; CI) for Cmax, AUCinf, and AUClast were 1.015 (0.946-1.088), 0.979 (0.914-1.049), and 0.995 (0.941-1.053) for ABP 215 versus bevacizumab. All CIs fell within the prespecified bioequivalence margin (0.80-1.25). Adverse events (AEs) occurred in 2/24 subjects receiving ABP 215 and 1/24 receiving bevacizumab. There were no deaths or AEs leading to study discontinuation; no subject was positive for binding anti-drug antibodies (ADAs). CONCLUSIONS: ABP 215 and bevacizumab showed PK similarity in Japanese men. Safety profiles were comparable between the two groups. The pharmacokinetics in Japanese subjects were consistent with those in a previous global PK equivalence study.

Nonclinical assessments of the potential biosimilar PF-06439535 and bevacizumab.

Bevacizumab, a recombinant humanized monoclonal antibody targeting vascular endothelial growth factor (VEGF), is approved for treatment of metastatic colorectal cancer, nonsquamous non-small-cell lung cancer, metastatic kidney cancer, and glioblastoma. To support clinical development of the potential bevacizumab biosimilar PF-06439535, nonclinical studies evaluated structural, functional, toxicological, and toxicokinetic similarity to bevacizumab sourced from the European Union (bevacizumab-EU) and United States (bevacizumab-US). Peptide mapping demonstrated the amino acid sequence of PF-06439535 was identical to bevacizumab-EU and bevacizumab-US. Biologic activity, measured via inhibition of VEGF-induced cell proliferation in human umbilical vein endothelial cells and binding to VEGF isoforms, was similar across the three drugs. In vivo similarity was demonstrated in cynomolgus monkeys administered intravenous PF-06439535 or bevacizumab-EU (0 or 10 mg/kg/dose twice weekly for 1 month; total of nine doses). Systemic exposure appeared similar and test article-related effects were limited to physeal dysplasia of the distal femur. The potential for non-target-mediated toxicity of PF-06439535 was evaluated in rats administered intravenous PF-06439535 (15 or 150 mg/kg/dose twice weekly for 15 days; total of five doses). Nonadverse higher liver weights and minimal sinusoidal cell hyperplasia were observed. Collectively, these studies demonstrated similarity of PF-06439535 to bevacizumab, supporting entry into clinical development.

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.

Antibody drug quantitation in coexistence with anti-drug antibodies on nSMOL bioanalysis.

Therapeutic monoclonal antibodies (mAbs) are developed for treatment of diverse cancers and autoimmune diseases. For expansion of mAbs approval against unapproved diseases and pharmaceutical development, pharmacokinetics study is very important. Bioanalysis provides one of the most essential index against pharmacokinetics information. So far, we developed useful method for bioanalysis of mAbs in plasma or serum, nSMOL: nano-surface and molecular-orientation limited proteolysis. This method can provide accurate and reproducible value of mAbs content in plasma. Quantification of mAbs using ELISA is strongly influenced by endogenous ligand or anti-drug antibodies. In this report, we exhibited the role of nSMOL proteolysis coupled to LC-MS/MS analysis against quantification of mAbs bound to some binding molecules. The ligands against mAbs do not affect quantification of mAbs concentration in plasma using nSMOL proteolysis. On the other hands, some anti-drug antibodies (ADA), such as idiotypic antibodies, inhibit quantification of mAbs using nSMOL proteolysis. Acid dissociation has some efficacy in accurate value of quantitation of ADA binding mAbs using nSMOL proteolysis coupled to LC-MS/MS analysis. Accordingly, we consider that nSMOL method will contribute to understanding of mAb PK data and therapeutic reference combining with ADA measurements.

A new reliable, transposable and cost-effective assay for absolute quantification of total plasmatic bevacizumab by LC-MS/MS in human plasma comparing two internal standard calibration approaches.

The quantification of monoclonal antibodies (mAbs) such as bevacizumab, a recombinant humanized immunoglobulin G1 (hIgG1), in biological fluids, is an essential prerequisite to any pharmacokinetic preclinical and clinical study. To date, reference techniques used to quantify mAbs rely on enzyme-linked immunosorbent assay (ELISA) lacking specificity. Furthermore, the commercially available ELISA kit to quantify bevacizumab in human plasma only assesses the free fraction of the drug. However, the conditions of storage and analysis of plasma samples could alter the physiological equilibrium between the free, bound and partially bound forms of bevacizumab and this could result in over- or underestimation of drug concentration. We developed a new assay for absolute quantification of total fraction of bevacizumab by liquid chromatography tandem mass spectrometry (LC-MS/MS) basing identification and quantification of bevacizumab on two specific peptides. In this report we compare our assay with two internal standard (IS) calibration approaches: one using a different human mAb (Trastuzumab) and the other using a stable isotope labeled specific peptide. After enrichment by affinity chromatography on protein A and concentration by ultrafiltration, human plasma samples were proteolyzed by trypsin. Linearity was established from 12.5 to 500µg/mL with an interday accuracy ranging from 101.7 to 110.6% and precision from 7.0% to 9.9%. This study demonstrates the importance of the choice of the IS in quantifying bevacizumab in human plasma and highlights the difficulty of reaching a reliable proteolysis with a sufficient recovery. We developed a reliable and cost-effective LC-MS/MS method to quantify total plasmatic fraction of bevacizumab in human plasma. Through our development we proposed a generic methodology easily transposable to quantify all IgG1 subclass very useful for clinical pharmacokinetics studies.

Development of an LC-MS/MS method with protein G purification strategy for quantifying bevacizumab in human plasma.

Biopharmaceutical products such as protein drugs and monoclonal antibodies (mAb) are currently of great interest with monoclonal antibody drugs being one of the fastest growing categories of biopharmaceutical products. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has gained high interest for measuring mAb drugs in biological samples in recent years due to its high selectivity. Bevacizumab is a humanized immunoglobulin G (IgG) mAb drug against human vascular endothelial cell growth factor A (VEGF-A). It is used for treating many types of cancers. Recent studies have indicated that clinical outcomes vary among patients treated with bevacizumab and produce various side effects, such as vascular disorders. In this study, we developed an LC-MS/MS method to quantify bevacizumab concentration. We selected readily available and economic materials for sample preparation to facilitate its wider use in clinical fields.-Protein G was used to trap bevacizumab from human plasma. In place of an extended stable isotope-labeled internal standard (SIL-IS), the IgG-based drug-IS tocilizumab was used because of its better calibration performance. The method was validated in terms of its precision, accuracy, linearity, and sensitivity. The accuracies which were expressed as percentage recoveries for three concentration levels were within 92.8 ± 3.2 to 112.7 ± 4.5%. Repeatability and intermediate precision in terms of peak area ratios were lower than 5.2 and 12.9% RSD, respectively. The application to patients' sample measurements revealed a wide individual variability of drug concentrations, and the proposed simple and general method may facilitate personalized medicine for improving therapeutic efficacy and safety. Graphical abstract ᅟ.

Efficient VEGF targeting delivery of DOX using Bevacizumab conjugated SiO2@LDH for anti-neuroblastoma therapy.

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis and is highly expressed in carcinoma, which make it an important target for tumor targeting therapy. Neuroblastoma is the main cause for cancer-related death in children. Like most solid tumors, it is also accompanied with the overexpression of VEGF. Doxorubicin Hydrochloride (DOX), a typical chemotherapeutic agent, exhibits efficient anticancer activities for various cancers. However, DOX, without targeting ability, usually causes severe damage to normal tissues. To overcome the shortages, we designed a novel nano-composite, which is Bevacizumab (Bev) modified SiO2@LDH nanoparticles (SiO2@LDH-Bev), loading with DOX to achieve targeting ability and curative efficiency. SiO2@LDH-DOX and SiO2@LDH-Bev-DOX nanoparticles were synthesized and the physicochemical properties were characterized by TEM detection, Zeta potential analysis, FTIR, Raman and XPS analysis. Then in vitro and in vivo anti-neuroblastoma efficiency, targeting ability and mechanisms of anti-carcinoma and anti-angiogenesis of SiO2@LDH-Bev-DOX were explored. Our results indicated that we obtained the core-shell structure SiO2@LDH-Bev with an average diameter of 253±10nm and the amount of conjugated Bev was 4.59±0.38µg/mg SiO2@LDH-Bev. SiO2@LDH-Bev-DOX could improve the cellular uptake and the targeting effect of DOX to brain and tumor, enhance the anti-neuroblastoma and anti-angiogenesis efficiency both in vitro and in vivo, and alleviate side effects of DOX sharply, especially hepatic injury. In addition, we also demonstrated that angiogenesis inhibitory effect was mediated by DOX and VEGF triggered signal pathways, including PI3K/Akt, Raf/MEK/ERK, and adhesion related pathways. In summary, SiO2@LDH-Bev could be a potential VEGF targeting nanocarrier applied in VEGF positive cancer therapy. STATEMENT OF SIGNIFICANCE: This paper explored that a novel core-shell structure nanomaterial SiO2@LDH and modified SiO2@LDH with Bevacizumab (Bev) to form a new tumor vasculature targeting nanocarrier SiO2@LDH-Bev as vector of DOX, which was not reported before. The results indicated that SiO2@LDH-Bev could improve the VEGF targeting ability, anti-neuroblastoma and anti-angiogenesis efficiency of DOX. At the same time, SiO2@LDH-Bev-DOX could erase the cardiac toxicity and hepatic injury coming from DOX. Tube formation showed SiO2@LDH-Bev-DOX had the strongest effect on inhibiting angiogenesis among all the four formulations. SiO2@LDH-Bev-DOX could downregulate expression of p-VEGFR and inhibit activation of the Raf/MEK/ERK, p38MAPK, PI3K/Akt and FAK signaling pathways to achieve the goal of anti-angiogenesis. This work provides a novel system for the safe and efficient use of Bev and DOX on Neuroblastoma and explores the mechanism of the function of nano carrier in cancer therapy both in vitro and in vivo.

LC-MS/MS strategies for therapeutic antibodies and investigation into the quantitative impact of antidrug-antibodies.

AIM: We aimed to establish novel, high-throughput LC-MS/MS strategies for quantification of monoclonal antibodies in human serum and examine the potential impact of antidrug antibodies. METHODOLOGY: We present two strategies using a thermally stable immobilized trypsin. The first strategy uses whole serum digestion and the second introduces Protein G enrichment to improve the selectivity. The impact of anti-trastuzumab antibodies on the methods was tested. CONCLUSION: Whole serum digestion has been validated for trastuzumab (LLOQ 0.25 µg/ml). Protein G enrichment has been validated for trastuzumab (LLOQ 0.1 µg/ml), bevacizumab (LLOQ 0.1 µg/ml) and adalimumab (LLOQ 0.25 µg/ml). We have shown the potential for anti-drug antibodies to impact on the quantification and we have subsequently established a strategy to overcome this impact where total quantification is desired.

A functional bioassay to determine the activity of anti-VEGF antibody therapy in blood of patients with cancer.

BACKGROUND: Only a small proportion of patients respond to anti-VEGF therapy, pressing the need for a reliable biomarker that can identify patients who will benefit. We studied the biological activity of anti-VEGF antibodies in patients' blood during anti-VEGF therapy by using the Ba/F3-VEGFR2 cell line, which is dependent on VEGF for its growth. METHODS: Serum samples from 22 patients with cancer before and during treatment with bevacizumab were tested for their effect on proliferation of Ba/F3-VEGFR2 cells. Vascular endothelial growth factor as well as bevacizumab concentrations in serum samples from these patients were determined by enzyme linked immunosorbent assay (ELISA). RESULTS: The hVEGF-driven cell proliferation was effectively blocked by bevacizumab (IC50 3.7 µg ml-1; 95% CI 1.7-8.3 µg ml-1). Cell proliferation was significantly reduced when patients' serum during treatment with bevacizumab was added (22-103% inhibition compared with pre-treatment). Although bevacizumab levels were not related, on-treatment serum VEGF levels were correlated with Ba/F3-VEGFR2 cell proliferation. CONCLUSIONS: We found that the neutralising effect of anti-VEGF antibody therapy on the biological activity of circulating VEGF can be accurately determined with a Ba/F3-VEGFR2 bioassay. The value of this bioassay to predict clinical benefit of anti-VEGF antibody therapy needs further clinical evaluation in a larger randomised cohort.

Simulations to Predict Clinical Trial Outcome of Bevacizumab Plus Chemotherapy vs. Chemotherapy Alone in Patients With First-Line Gastric Cancer and Elevated Plasma VEGF-A.

To simulate clinical trials to assess overall survival (OS) benefit of bevacizumab in combination with chemotherapy in selected patients with gastric cancer (GC), a modeling framework linking OS with tumor growth inhibition (TGI) metrics and baseline patient characteristics was developed. Various TGI metrics were estimated using TGI models and data from two phase III studies comparing bevacizumab plus chemotherapy vs. chemotherapy as first-line therapy in 976 GC patients. Time-to-tumor-growth (TTG) was the best TGI metric to predict OS. TTG, Eastern Cooperative Oncology Group (ECOG) score, albumin level, and Asian ethnicity were significant covariates in the final OS model. The model correctly predicted a decreased hazard ratio favorable to bevacizumab in patients with high baseline plasma VEGF-A above the median of 113.4 ng/L. Based on trial simulations, in trials enrolling patients with elevated baseline plasma VEGF-A (500 patients per arm), the expected hazard ratio was 0.82 (95% prediction interval: 0.70-0.95), independent of ethnicity.

Total and not bevacizumab-bound vascular endothelial growth factor as potential predictive factors to bevacizumab-based chemotherapy in colorectal cancer.

AIM: To identify suitable biomarkers of response to bevacizumab (BV) - it remains an open question. The measurement of serum vascular endothelial growth factor (VEGF) has been proposed as a predictive factor for this drug, even if literature data are contradictory. METHODS: We prospectively evaluated the role of BV, total and not BV-bound VEGF and angiopoietin-2 (Ang-2) serum levels as potential predictive factors of response for BV in combination with an oxaliplatin-based chemotherapy. BV, Ang-2, total and not BV-bound VEGF levels were measured at baseline, before 2(nd) and 5(th) cycle of oxaliplatin-based chemotherapy in 20 consecutive metastatic colorectal cancer patients. RESULTS: Results were correlated to response to treatment. Variability in BV levels have been found, with decreased level in less responding patients. In particular, the concentration of BV increased of 3.96 ± 0.69 folds in serum of responsive patients after 3 more cycles of therapy compared to those with stable or progressive disease with a 0.72 ± 0.25 and 2.10 ± 0.13 fold increase, respectively. The determination of free and total VEGF demonstrated that the ratio between the two values, evaluated immediately before the 2(nd) and the 5(th) cycle of therapy, decreased from 26.65% ± 1.33% to 15.50% ± 3.47% in responsive patients and from 53.41% ± 4.75 to 34.95% ± 2.88% in those with stable disease. Conversely, in those with progression of disease, the ratio showed the opposite behavior coming up from 25.99% ± 5.23% to 51.71% ± 5.28%. The Ang-2 levels did not show any relationship. CONCLUSION: Our data show that the ratio of not BV-bound VEGF to total VEGF serum and BV plasma concentrations for predicting the response to BV plus oxaliplatin-based chemotherapy could be a promising biomarker of response to BV.

Phase 1 Study of ABT-751 in Combination With CAPIRI (Capecitabine and Irinotecan) and Bevacizumab in Patients With Advanced Colorectal Cancer.

ABT-751 is an orally bioavailable sulfonamide with antimitotic properties. A nonrandomized phase 1 dose-escalation study of ABT-751 in combination with CAPIRI (capecitabine and irinotecan) and bevacizumab was conducted to define the maximum tolerated dose, dose-limiting toxicity (DLT), and pharmacokinetics in patients with advanced colorectal cancer. Patients were treated with ABT-751 daily for 7 days (alone) and then began 21-day cycles of treatment with ABT-751 daily and capecitabine twice daily for 14 days plus irinotecan on day 1 intravenously. Bevacizumab was added as standard of care at 7.5 mg/kg on day 1 after the first 2 dose levels. Because of intolerance to the regimen, a reduced dose of ABT-751 was also explored with reduced-dose and full-dose CAPIRI with bevacizumab. ABT-751 and irinotecan pharmacokinetics, ABT-751 glucuronidation, and protein binding were explored. Twenty-four patients were treated over 5 dose levels. The maximum tolerated dose was ABT-751 125 mg combined with full-dose CAPIRI and bevacizumab 7.5 mg/kg on day 1. DLTs were hypokalemia, elevated liver tests, and febrile neutropenia. ABT-751 is metabolized by UGT1A8 and to a lesser extent UGT1A4 and UGT1A1. Irinotecan and APC exposure were increased, SN-38 exposure was similar, and SN-38 glucuronide exposure was decreased. Clinically relevant alterations in ABT-751 and irinotecan pharmacokinetics were not observed. Despite modest efficacy, the combination of ABT-751, CAPIRI, and bevacizumab will not be studied further in colorectal cancer.

Complementary effects of bevacizumab and MMC in the improvement of surgical outcome after glaucoma filtration surgery.

PURPOSE: To determine the optimum administration route of bevacizumab after glaucoma filtering surgery (GFS) and to investigate whether a reduced dose of mitomycin-C (MMC) in combination with bevacizumab could improve surgical outcome with a reduced incidence of side-effects. METHODS: Plasma levels of bevacizumab were determined via ELISA after intracameral (IC), subconjunctival (SC) and intravitreal (IV) injections in mice, subjected to a mouse model of GFS. Application of MMC was compared to bevacizumab (SC, 25 µg) and to the combined use of both adjuvants. Surgical sponges soaked in MMC 0.02% or 0.01% were exposed to the sclera for 1 or 2 min. Treatment outcome was studied by bleb investigation. RESULTS: The three administration routes of bevacizumab equally improved surgical outcome. The VEGF antibody was detected at relatively high levels in plasma shortly after IV injection, whereas it was minimally absorbed after IC and SC injections. Both bevacizumab (SC) and MMC 0.02% (2 min) similarly increased bleb area. As compared to MMC, the combined injection with bevacizumab induced an additional effect on surgical outcome. Exposure of MMC 0.02% for 1 or 2 min together with bevacizumab equally improved surgical outcome, but 2 min application induced corneal toxicity. The combined use of bevacizumab and 1-min MMC 0.01% also improved surgical outcome compared to monotherapy, although to a lesser extent than the combination with 1-min MMC 0.02%. CONCLUSIONS: Adjunctive bevacizumab not only enhances the beneficial effect of MMC on surgical outcome, but also allows reducing the administration time of MMC 0.02%, thereby eliminating its toxic effects on the cornea.