Stability assessment of FDA-approved ramucirumab monoclonal antibody; validated SE-HPLC method for degradation pattern evaluation.

Ramucirumab (RAMU) is a recently US Food and Drug Administration-approved monoclonal antibody that is included in various anticancer protocols. It has a structural complexity and high degradation risk that have a significant effect on its safety and effectiveness. The major aim of this work was to assess the degradation pattern of RAMU based on physicochemical characterization. Mechanical agitation, repeated freeze-thaw cycles, pH and temperature were the selected stress conditions to which RAMU samples were subjected. The SE-HPLC method was applied and validated to monitor the RAMU monomer along with its aggregates and/or fragments. The purity of the separated peaks together with system suitability parameters were determined through the calculation of percentage purity and percentage drop in RAMU concentration. The results were interpreted by correlating them with those of dynamic light scattering and reducing and non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Samples incubated at pH 2.0-10.0 and 37°C for up to 4 weeks were analysed, recording detection of reversed phase (RP) aggregates and low molecular weight peptide fragments. Similarly, samples under short-term storage conditions of 4 weeks at different temperatures (-20, 2-8, 25, 37 and 50°C) showed low molecular weight peptide fragments but to a lesser extent. These results highlight the alarming effect on RAMU multidose vial efficacy and safety.

Simple Addition of Glycine in Trifluoroacetic Acid-Containing Mobile Phases Enhances the Sensitivity of Electrospray Ionization Mass Spectrometry for Biopharmaceutical Characterization.

Trifluoroacetic acid (TFA) is a commonly used mobile phase additive in liquid chromatography-mass spectrometry (LC-MS)-based biopharmaceutical characterization to enhance reversed-phase chromatographic performance of peptide separation; however, it leads to significant mass spectrometry signal suppression during electrospray ionization. Previous studies have shown that introducing large amounts of carboxylic acids or ammonium hydroxide to LC eluents postcolumn can improve MS sensitivity. In this study, we discovered glycine as a simple additive for TFA mobile phases, which mitigates ion suppression through a similar mechanism but in a more effective way than weak acid or weak base and boosts mass spectrometry responses (signal-to-noise ratio) of peptides by more than 1 order of magnitude on average after directly adding a small amount (e.g., 2 mM) into TFA mobile phases without compromising the chromatographic performance of peptide separation. Other small molecule additives in TFA mobile phases, such as amino acids containing extended side chains with different chemical properties and glycine-based variants, were also evaluated. The results demonstrated that glycine offered the best response boosting on peptides. The discovery of this glycine additive in TFA mobile phases provides a simple and conventional approach to achieve greater mass spectrometry detection sensitivity than TFA mobile phases for LC-MS-based characterization of biopharmaceuticals.

Incidence and Management of Therapeutic Monoclonal Antibody Interference in Monoclonal Gammopathy Monitoring.

BACKGROUND: The treatment of multiple myeloma (MM) has been revolutionized by the introduction of therapeutic monoclonal antibodies (tmAbs). Daratumumab, a human IgG1/κ tmAb against CD38 on plasma cells, has improved overall survival in refractory MM and was recently approved as a frontline therapy for MM. Work on tmAb interference with serum protein electrophoresis (SPE) during MM monitoring has failed to provide information for laboratories on incidence of interference and effective methods of managing the interference at a practicable level. We aimed to evaluate daratumumab and elotuzumab interference in a large academic hospital setting and implement immediate solutions. METHODS: We identified and chart reviewed all cases of possible daratumumab interference by electrophoretic pattern (120 of 1317 total cases over 3 months). We retrospectively reviewed SPE cases in our laboratory to assess clinical implications of tmAb interference before the laboratory was aware of tmAb treatment. We supplemented samples with daratumumab and elotuzumab to determine the limits of detection and run free light chain analysis. RESULTS: Approximately 9% (120 of 1317) of tested cases have an SPE and/or immunofixation electrophoresis (IFE) pattern consistent with daratumumab, but only approximately 47% (56) of these cases were associated with daratumumab therapy. Presence of daratumumab led to physician misinterpretation of SPE/IFE results. Limits of daratumumab detection varied with total serum gammaglobulin concentrations, but serum free light chain analysis was unaffected. CONCLUSIONS: Clinical laboratories currently rely on interference identification by electrophoretic pattern, which may be insufficient and is inefficient. Critical tools in preventing misinterpretation efficiently include physician education, pharmacy notifications, separate order codes, and interpretive comments.

PNL2: A Useful Adjunct Biomarker to HMB45 in the Diagnosis of Uterine Perivascular Epithelioid Cell Tumor (PEComa).

Perivascular epithelioid cell tumors (PEComa) are rare neoplasms characterized by co-expression of melanocytic and muscle markers. HMB45 and Melan-A are used to confirm a PEComa diagnosis; however, both are often focally expressed and sensitivity for Melan-A is low. PNL2 is a reliable biomarker for epithelioid melanoma and renal angiomyolipoma/PEComa. The objective of this study was to determine PNL2 utility in diagnosing uterine PEComas as well as distinguishing PEComas from uterine smooth muscle tumors (SMTs). Twenty-one uterine PEComas and 45 SMTs were analyzed for PNL2; a subset was also stained for HMB45, Melan-A, Cathepsin-K, Desmin, and h-Caldesmon. Cases were scored as negative (0), focal (<10% of tumor cells), or patchy to diffusely positive (>10% of tumor cells). PEComas were positive for PNL2, HMB45, and Melan-A in 86%, 100%, and 57% of cases, respectively. In PEComas, PNL2 was patchy to diffusely positive more frequently (10/18, 56%) than Melan-A (4/12, 33%). In contrast, 2 of 45 (4%) SMTs were focally PNL2 positive; HMB45 was focally positive in 4 SMTs (11%) and all were negative for Melan-A. Desmin and h-Caldesmon were positive in 90% and 57% of PEComas, and 91% and 82% of SMTs. Cathepsin-K was positive in 100% of PEComas and 93% of SMTs. PNL2 is a useful biomarker for the diagnosis of uterine PEComa, with comparable sensitivity and specificity to HMB45. In contrast, PNL2 stains more PEComas when compared with Melan-A. Cathepsin-K, Desmin, and h-Caldesmon are of little utility for distinguishing PEComas and SMTs; however, lack of Cathepsin-K argues against PEComa. These results suggest that PNL2 should be used in conjunction with HMB45 in the diagnosis of PEComa of the uterine corpus.

A cell-based immunogenicity assay to detect antibodies against chimeric antigen receptor expressed by tisagenlecleucel.

The use of T-cells expressing Chimeric Antigen Receptors (CARs) offers new opportunities for cancer treatment, as well as new challenges for the bioanalysis of this new class of drugs. The analysis of humoral immunogenicity (anti-drug antibodies) against CARs could be performed with a bridging ELISA, using labeled CAR fragments. However, outside of its native cell membrane environment and without potential interaction partners on the cell surface, a labeled or coated recombinant CAR fragment may structurally differ from the membrane-bound CAR expressed on CAR-T cells. Consequently, immunogenicity to CARs may be missed due to the artificial nature of a ligand binding assay setup. T-cell lines expressing the CAR offer the opportunity to measure anti-drug antibodies to the CAR in its natural cell environment, as an alternative to ligand-binding assays. Here we describe a novel, flow cytometry-based humoral immunogenicity assay for tisagenlecleucel (CTL019, Kymriah®) using a human T-cell line that expresses murine CAR19. The assay described here was fully validated according to health authority guidelines for the development and validation of immunogenicity assays and has a sensitivity of 100 ng/mL. A good correlation of screening assay signal strengths to titer assay results was observed while exploring options to increase titration assay throughput. Pre-existing antibodies against the cell line used in the assay as well as against the CAR itself complicate the assay and data interpretation.

Enzyme linked immunosorbent assay for the quantification of nivolumab and pembrolizumab in human serum and cerebrospinal fluid.

Immunotherapy with monoclonal antibodies targeting the programmed-death-1 (PD-1) receptor has become standard of care for an increasing number of tumor types. Pharmacokinetic studies may help to optimize anti-PD-1 therapy. Therefore, accurate and sensitive determination of antibody concentrations is essential. Here we report an enzyme linked immunosorbent assay (ELISA) capable of measuring nivolumab and pembrolizumab concentrations in serum and cerebrospinal fluid (CSF) with high sensitivity and specificity. The assay was developed and validated based on the specific capture of nivolumab and pembrolizumab by immobilized PD-1, with subsequent enzymatic chemiluminescent detection by anti-IgG4 coupled with horse radish peroxidase (HRP). The lower limit of quantification for serum and CSF was 2 ng/mL for both anti-PD-1 agents. The ELISA method was validated and showed long term sample stability of >1 year. This method is reliable, relatively inexpensive and can be used in serum and CSF from pembrolizumab and nivolumab treated patients.

A Novel Online Four-Dimensional SEC×SEC-IM×MS Methodology for Characterization of Monoclonal Antibody Size Variants.

The determination of size variants is a major critical quality attribute of a therapeutic monoclonal antibody (mAb that may affect the drug product safety, potency, and efficacy. Size variant characterization often relies on size-exclusion chromatography (SEC), which could be hampered by difficult identification of peaks. On the other hand, mass spectrometry (MS)-based techniques performed in nondenaturing conditions have proven to be valuable for mAb-related compound characterization. On the basis of the observation that limited SEC performance was observed in nondenaturing MS compatible ammonium acetate buffer compared with classical phosphate salts, a multidimensional analytical approach was proposed. It combines comprehensive online two-dimensional chromatography (SEC×SEC), with ion mobility and mass spectrometry (IM-MS) in nondenaturing conditions for the characterization of a variety of mAbs. We first exemplify the versatility of our approach for simultaneous detection, identification, and quantitation of adalimumab size variants. Benefits of the SEC×SEC-native IM×MS were further highlighted on forced degraded pembrolizumab and bevacizumab samples, for which the 4D setup was mandatory to obtain an extensive and unambiguous identification, and accurate quantitation of unexpected high/low molecular weight species (HMWS and LMWS). In this specific context, monomeric conformers were detected by IM-MS as HMWS or LMWS. Altogether, our results emphasize the power of comprehensive 2D LC×LC setups hyphenated to IM×MS in nondenaturing conditions with unprecedented performance including: (i) maintaining optimal SEC performance (under classical nonvolatile salt conditions), (ii) performing online native MS identification, and (iii) providing IM-MS conformational characterization of all separated size variants.

Use of Cyclodextrin as a Novel Agent in the SEC-HPLC Mobile Phase to Mitigate the Interactions of Proteins or Peptide or their Impurities with the Residual Silanols of Commercial SEC-HPLC Columns with Improved Separation and Resolution.

PURPOSE: Accurate quantification of the intact proteins, antibodies or peptides and their impurities without interaction to silanols of HPLC column. METHODS: Hydroxypropyl ß Cyclodextrin (HPCD) is added in the mobile phase at different concentrations. Different commercial SEC-HPLC columns and biologics with a molecular weight ranging from 5.8 kDa to 150kDa were assessed with and without cyclodextrin. RESULTS: Addition of non-ionic sugars such as Hydroxypropyl ß Cyclodextrin in the mobile phase, resulted improved peak performance such as theoretical plates, peak resolution, peak width, peak height, and improved quantification of aggregates in biologics such as antibodies Humira and Actemra, and peptides such as insulin. There is an increase in peak height, reduced retention time, increased plate and reduced peak width with increasing concentration of cyclodextrin studied. DISCUSSION: High ionic strength, basic amino acids such as arginine, organic solvents (with a concentration low enough not to precipitate protein), sodium perchlorate and ion pairing agents in the mobile phase used for separation of peptides, proteins and antibodies to prevent silanol interaction. These commonly used solutions are not always successful, as they not only interact with the biologic, but are sometimes, not compatible. The non-ionic cyclodextrin itself does not cause protein aggregation but prevents the nonspecific binding or interaction of protein itself and thereby allowing for improved resolution, and accurate quantification of aggregates in antibodies, and peptides. The data on the separation in presence of cyclodextrin in the mobile phase showed higher peak resolution, improved peak shape, accurate apparent molecular weight, improved efficiency, and less peak tailing for biological products. CONCLUSION: Hydroxypropyl ß Cyclodextrin in the mobile phase, resulted improved SEC-HPLC resolution, and quantitation of aggregates in biologics by preventing the interaction of biologics to silanol of the commercial SEC-HPLC columns.

Development of an Enzyme-Linked Immune Sorbent Assay to Measure Nivolumab and Pembrolizumab Serum Concentrations.

BACKGROUND: Treatment with monoclonal antibodies (mAbs) against programmed cell death protein 1 receptor is subject to high variation in treatment outcome among cancer patients. For these agents, no exposure-response (ER) relationships have been investigated in routine health care settings. However, ER relationships have been identified for several other mAbs used in oncology. Methods to conveniently measure serum concentrations of anti-programmed cell death protein 1 mAbs in routine health care may clarify possible ER relationships. Therefore, the authors aimed to develop an enzyme-linked immune sorbent assay (ELISA) for the measurement of both nivolumab and pembrolizumab serum concentrations of treated cancer patients. METHODS: Optimal capture antigen and detection antibody concentrations were selected based on titrations. Nivolumab calibration standards ranging from 0.2 to 300 ng/mL were tested in duplicate. Accuracy was assessed in 2 recovery experiments. Intra- and interassay variations were assessed on 3 different days by 2 independent technicians. The developed ELISA was also set up for pembrolizumab calibration curves. Cross-reactivity of nivolumab measurements with ipilimumab was assessed. Of one nivolumab treated patient, serum concentrations in follow up samples were measured and presented. RESULTS: Nivolumab calibration standards of 0.20-25 ng/mL were used. Nivolumab trough concentrations after 1 cycle in 8 patients ranged from 17.3 to 31.1 mcg/mL. The range of accuracy was 84%-105%, whereas intra- and interassay variations showed a coefficient of variation of 5.5% and 10.1%, respectively. No cross-reactivity with ipilimumab was detected. Pembrolizumab trough concentrations (n = 8) ranged from 9.1 to 19.7 mcg/mL after 1 infusion. CONCLUSIONS: The in-house-developed ELISA provides the opportunity to measure both nivolumab and pembrolizumab serum concentrations. This may help identify possible ER relationships in treated cancer patients and may potentially lead to dose adjustments in the future.

Mass spectrometry characterization of DOTA-Nimotuzumab conjugate as precursor of an innovative ß- tracer suitable in radio-guided surgery.

The aim of the present work has been the mass spectrometry characterization of the Nimotuzumab (NIM) antibody chemically modified with the bifunctional chelating agent para-S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraaza cyclododecanetetraacetic acid (p-SCN-Bn-DOTA). The conjugate, upon labeling with the pure ß--emitter 90Y3+, could represent a promising candidate as radiotracer for an innovative radio-guided surgery (RGS) technique, developed and patented by researchers of our group, which uses a probe system for intraoperative detection of tumor residues exploiting the selective uptake of ß--emitting tracers. The results reported in this study show that multiple DOTA molecules bind to lysine residues of both light and heavy chains of the antibody and, probably, some of them are linked to the variable region of antibody. Moreover, the new mass spectrometric analysis highlights the presence of unreacted NIM in the final product. The information obtained by this work is of fundamental importance in the perspective to utilize this conjugate as a radiocompound after its labeling with 90Y3+ radioisotope. Indeed, the conjugation efficiency and the presence of unreacted NIM affect the specific activity of the final radiotracer which binds specific receptor.

A Harmonization Study for the Use of 22C3 PD-L1 Immunohistochemical Staining on Ventana's Platform.

INTRODUCTION: Immunotherapy is a novel treatment for lung cancer. Pembrolizumab (Merck Sharp and Dohme, Kenilworth, NJ) is a monoclonal antibody against programmed cell death 1 that has been approved for use with NSCLC together with a companion diagnostic by Dako (Carpinteria, CA). Ventana's BenchMark XT (Ventana Medical Systems, Tucson, AZ) is a widely used immunohistochemical (IHC) platform. However, data on its reliability and reproducibility with the 22C3 antibody are scant. METHODS: We performed a comprehensive calibration of 22C3 programmed cell death ligand 1 (PD-L1) staining on the BenchMark XT platform using Dako's prediluted 22C3 anti-PD-L1 primary antibody with two of Ventana's detection systems. Forty-one random cases of NSCLC were then independently evaluated by two pathologists. Each case was scored using Dako- or Ventana-stained slides. The scores obtained with the two 22C3 Ventana assays were compared with those obtained using the Dako 22C3 IHC platform. RESULTS: The Dako IHC platform stratified eight, seven, and 26 cases as being strongly positive, weakly positive, and negative for PD-L1, respectively, whereas 36 of 41 cases (87.8%) had the same results with Ventana's UltraView 22C3 protocol (Pearson's correlation score 0.91, p < 0.0001). Moreover, 35 of 41 cases (85.3%) had the same results with Ventana's OptiView 22C3 protocol (Pearson's correlation score 0.89, p < 0.0001). CONCLUSIONS: The results of this study demonstrate that the same PD-L1 IHC algorithm can be reliably applied to Ventana's BenchMark XT platform. Furthermore, we were able to detect all of the strongly positive cases with high interobserver and intraobserver agreement by using the Ventana platform. These findings suggest that the Ventana platform can be used to stratify patients for pembrolizumab-based immunotherapy.

Fab(nimotuzumab)-HYNIC-99mTc: Antibody Fragmentation for Molecular Imaging Agents.

Finally, fast blood clearance nimotuzumab is a humanized monoclonal antibody that recognise, with high specific affinity, the epidermal growth factor receptor (EGF-R) which play an important role in the growth process associated with many solid tumors. In this work, the whole antibody was digested with papain in order to generate a Fab fragment, derivatized with NHS-HYNIC-Tfa and radiolabel with technetium-99m (99mTc) as a potential agent of molecular imaging of cancer. Both, whole and fragment radiolabels were in-vivo and in-vitro characterized. Radiolabeling conditions with Tricine as coligand and quality controls were assessed to confirm the integrity of the labeled fragment. Biodistribution and imaging studies in normal and spontaneous adenocarcinoma mice were performed at different times to determine the in-vivo characteristics of the radiolabel fragment. Tumor localization was visualized by conventional gamma camera imaging studies, and the results were compared with the whole antibody. Also, an immunoreactivity assay was carried out for both. The results showed clearly the integrity of the nimotuzumab fragment and the affinity by the receptor was verified. Fab(nimotuzumab)-HYNIC was obtained with high purity and a simple strategy of radiolabeling was performed. Finally, a fast blood clearance was observed in the biodistribution studies increasing the tumor uptake of Fab(nimotuzumab)- HYNIC-99mTc over time, with tumor/muscle ratios of 3.81 ± 0.50, 5.16 ± 1.97 and 6.32 ± 1.98 at 1 h, 4 h and 24 h post injection. Urinary excretion resulted in 32.89 ± 3.91 %ID eliminated at 24 h. Scintigraphy images showed uptake in the tumor and the activity in non-target organs was consistent with the biodistribution data at the same time points. Hence, these preliminary results showed important further characteristic of Fab(nimotuzumab)-HYNIC-99mTc as a molecular imaging agent of cancer.

The clinical relevance of early anti-adalimumab antibodies detection in rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis: A prospective multicentre study.

OBJECTIVES: To evaluate the relevance of anti-adalimumab (anti-ADA) antibodies (Abs) and their relationship with clinical/laboratory features in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA). METHODS: Fifty-eight patients affected with RA, AS and PsA were prospectively enrolled. Clinical/laboratory characteristics, disease activity, anti-ADA, anti-nuclear (ANA), anti-double strand (ds)DNA, anti-extractable nuclear antigens (anti-ENA) and anti-phospholipid Abs (aPL) were evaluated at baseline, 4, 12 and 24 weeks of adalimumab treatment. RESULTS: Anti-ADA Abs were observed in 11/58 (19%) patients; they were detected within the 4th week of therapy in 90.9% of the positive subjects. Anti-ADA positivity was associated with significantly lower mean adalimumab serum levels (P<0.05). Treatment failure was observed in 20/58 (34.5%) patients and was significantly associated with anti-ADA Abs (P<0.05). Mean adalimumab serum levels were significantly lower in patients with treatment failure than in the responders one, both in the whole cohort (P<0.01) and in the group of anti-ADA positive patients (P<0.01). Adverse events happened more often in anti-ADA positive then in anti-ADA negative patients (27.3% vs 14.9%). CONCLUSIONS: Anti-ADA abs could be considered an early marker associated to a poor clinical response to adalimumab treatment. Routine ANA/anti-ENA/aPL monitoring did not reveal as useful tools to predict the development of anti-ADA abs.

Chemical de-conjugation for investigating the stability of small molecule drugs in antibody-drug conjugates.

Antibody-drug conjugates (ADCs) offer new therapeutic options for advanced cancer patients through precision killing with fewer side effects. The stability and efficacy of ADCs are closely related, emphasizing the urgency and importance of gaining a comprehensive understanding of ADC stability. In this work, a chemical de-conjugation approach was developed to investigate the in-situ stability of the small molecule drug while it is conjugated to the antibody. This method involves chemical-mediated release of the small molecule drug from the ADC and subsequent characterization of the released small molecule drug by HPLC. The feasibility of this technique was demonstrated utilizing a model ADC containing a disulfide linker that is sensitive to the reducing environment within cancer cells. Five reducing agents were screened for use in de-conjugation; tris(2-carboxyethyl) phosphine (TCEP) was selected for further optimization due to its high efficiency and clean impurity profile. The optimized de-conjugation assay was shown to have excellent specificity and precision. More importantly, it was shown to be stability indicating, enabling the identification and quantification of the small molecule drug and its degradation products under different formulation pHs and storage temperatures. In summary, the chemical de-conjugation strategy demonstrated here offers a powerful tool to assess the in-situ stability of small molecule drugs on ADCs and the resulting information will shed light on ADC formulation/process development and storage condition selection.

[Paclitaxel-bevacizumab is a possible alternative as salvage chemotherapy in advanced non-small cell bronchial carcinoma]. / L'association paclitaxel-bevacizumab est une alternative intéressante dans le traitement des cancers bronchopulmonaires non épidermoïdes avancés en troisième ligne et plus.

INTRODUCTION: Bevacizumab is recommended in first line chemotherapy for advanced non-squamous non-small cell lung cancer (NSCLC). Paclitaxel is a doublet drug also widely used in cisplatin-based regimens. Paclitaxel plus bevacizumab is a standard regimen as first line treatment of metastatic breast cancer. Since there is no guideline for third line treatment of NSCLC, some oncology units use paclitaxel-bevacizumab in some NSCLC patient after relapse of the second line. The aim of this study was to assess retrospectively the feasibility and efficacy of this treatment option in stage IV NSCLC. METHODS: Patients who had received the combination of paclitaxel (80 to 90 mg/m(2) in a weekly schedule) and bevacizumab (7.5 to 15 mg/kg every 21 days) in the thoracic oncology departments of two university hospitals in the Rhone-Alpes Department were retrospectively reviewed. RESULTS: Twelve patients underwent this treatment. Their mean age was 56 years and their performance status was less or equal to 1 in 50 % of the cases. The chemotherapy was given as fifth line in 67 % of the patients and 67 % were antiangiogenic naïve. They received a mean of 6 courses. The overall response rate was 33 % and the disease control rate 66 %. Median progression-free survival was 5.1 months (95 %CI 1.0-9.1). Ten patients (82 %) experienced toxicity, the majority grade 1 to 2 events, and only one a grade 3 event (febrile neutropenia). There were no severe bleeding episodes. CONCLUSION: Combined paclitaxel-bevacizumab chemotherapy seems feasible in patients with NSCLC. The toxicity profile is acceptable. This regimen should be evaluated in further prospective studies.

Quantification of human mAbs in mouse tissues using generic affinity enrichment procedures and LC-MS detection.

BACKGROUND: The disease state can modulate the penetration of large antibody-sized therapeutic molecules into affected tissues. Suitable bioanalytical methods are required for the quantitative analysis of drug tissue levels to enable a better understanding of the parameters influencing drug penetration and target engagement. RESULTS: Described is a sensitive and selective LC-MS/MS assay for the quantification of human mAb molecules in mouse tissues. By homogenizing tissues directly into serum, a common serum calibration curve can be used for multiple tissues. A generic procedure was used for affinity enrichment. An analytical range of 20 - 20,000 ng/ml was achieved in serum. CONCLUSION: The method described here can be applied for the quantitative analysis of mAb and Fc-fusion therapeutic molecules in a variety of animal tissue matrices.

Full antibody primary structure and microvariant characterization in a single injection using transient isotachophoresis and sheathless capillary electrophoresis-tandem mass spectrometry.

Here we report the complete characterization of the primary structure of a multimeric glycoprotein in a single analysis by capillary electrophoresis (CE) coupled to mass spectrometry (MS). CE was coupled to electrospray ionization tandem MS by means of a sheathless interface. Transient isotachophoresis (t-ITP) was introduced in this work as an electrokinetically based preconcentration technique, allowing injection of up to 25% of the total capillary volume. Characterization was based on an adapted bottom-up proteomic strategy. Using trypsin as the sole proteolytic enzyme and data from a single injection per considered protein, 100% of the amino acid sequences of four different monoclonal antibodies could be achieved. Furthermore, illustrating the effectiveness and overall capabilities of the technique, the results were possible through identification of peptides without tryptic miscleavages or posttranslational modifications, demonstrating the potency of the technique. In addition to full sequence coverages, posttranslational modifications (PTMs) were simultaneously identified, further demonstrating the capacity of this strategy to structurally characterize glycosylations as well as faint modifications such as asparagine deamidation or aspartic acid isomerization. Together with the exquisite detection sensitivity observed, the contributions of both the CE separation mechanism and selectivity were essential to the result of the characterization with regard to that achieved with conventional MS strategies. The quality of the results indicates that recent improvements in interfacing CE-MS coupling, leading to a considerably improved sensitivity, allows characterization of the primary structure of proteins in a robust and faster manner. Taken together, these results open new research avenues for characterization of proteins through MS.

Quantification, microbial contamination, physico-chemical stability of repackaged bevacizumab stored under different conditions.

In this work, the stability of Bevacizumab (Avastin(®)) repackaged in individual 1 mL single-use syringes and stored at different conditions was assessed. Bevacizumab repackaged in single-use syringes results from the off-label use of the drug as an intravitreal agent in the treatment of retinal diseases. Bevacizumab stability was assessed by assaying the anti-VEGF activity using an indirect ELISA method and a Dynamic Light Scattering study. The thermal stability of the drug was also studied by calorimetric analysis, aimed to evaluate thermodynamic parameters associated to the thermal unfolding process. Furthermore, microbiological and fungal tests on the Bevacizumab syringes were performed. As a result, a significant decrease of the anti-VEGF activity was detected when syringes were exposed to UV light at a temperature of 37°C. Under these conditions, the Dynamic Light Scattering study showed an increase of the average size of Bevacizumab; probably due to aggregation. In conclusion, Bevacizumab stability, when stored under different conditions, was assessed considering three different aspects: anti-VEGF activity, microbial contamination and physico-chemical properties. Bevacizumab was found to be stable, under sterile conditions, for 3 months at 4°C and for 7 days at room temperature, exposed to indirect light sources, while a brief exposure of the drug to direct UV radiation proved detrimental to drug stability.