Development and validation of ELISA for Herceptin detection in human serum

Analysis of human epidermal growth factor receptor 2 interaction on aptamer-probed interdigitated electrode for breast cancer diagnosis

Breast cancer has been reported to be high in its incidence with women, and early identification of breast cancer helps to improve and provide an effective treatment. Tumor markers are active substances; in particular, human epidermal growth factor receptor 2 (HER2) is over-expressed at the level of 20%-30%. This research work developed a highly sensitive HER2 biosensor on the interdigitated electrode (IDE) by using aptamer as a detection probe. To enhance the analytical performances, aptamer was attached to the gold nanoparticle and immobilized on the IDE through a chemical linker [(3-aminopropyl)triethoxysilane]. On the aptamer conjugation, HER2 was quantified through current-volt measurements, and the limit of detection of HER2 was calculated as 1 pg/mL on a linear range from 0.1 to 3000 pg/mL at an R2 (regression coefficient) of 0.9657. Further, a selective performance with human serum increased the current responses by increasing HER2 concentrations. Specific experiments with control protein and complementary aptamer sequence failed to enhance the current responses. This HER2 biosensor reflects the occurrence of breast cancer at its lower abundance and helps to identify the associated complications.

Adeno-associated virus-mediated trastuzumab delivery to the central nervous system for human epidermal growth factor receptor 2+ brain metastasis

Trastuzumab improves overall survival for HER2+ breast cancer, but its short half-life in the cerebrospinal fluid (~2-4 days) and delivery limitations restrict the ability to target HER2+ central nervous system (CNS) disease. We developed an adeno-associated virus (AAV) vector expressing a codon-optimized, ubiquitin C (UbC)-promoter-driven trastuzumab sequence (AAV9.UbC.trastuzumab) for intrathecal administration. Transgene expression was evaluated in adult Rag1 knockout mice and rhesus nonhuman primates (NHPs) after a single intracerebroventricular (ICV) or intra-cisterna magna (ICM) AAV9.UbC.trastuzumab injection, respectively, using real-time PCR, ELISA, Western blot, in situ hybridization, single-nucleus RNA sequencing, and liquid chromatography-mass spectrometry; antitumor efficacy was evaluated in brain xenografts using HER2+ breast cancer cell lines (BT-474, MDA-MB-453). Transgene expression was detected in brain homogenates of Rag1 knockout mice following a single ICV injection of AAV9.UbC.trastuzumab (1 × 1011 vector genome copies [GC]/mouse) and tumor progression was inhibited in xenograft models of breast-to-brain metastasis. In NHPs, ICM delivery of AAV9.UbC.trastuzumab (3 × 1013 GC/animal) was well tolerated (36-37 days in-life) and resulted in transgene expression in CNS tissues and cerebrospinal fluid at levels sufficient to induce complete tumor remission in MDA-MB-453 brain xenografts. With AAV9's proven clinical safety record, this gene therapy may represent a viable approach for targeting HER2 + CNS malignancies.

No Interference of H9 Extract on Trastuzumab Pharmacokinetics in Their Combinations

Trastuzumab is used to treat breast cancer patients overexpressing human epidermal growth factor receptor 2, but resistance and toxicity limit its uses, leading to attention to trastuzumab combinations. Recently, the synergistic effect of trastuzumab and H9 extract (H9) combination against breast cancer has been reported. Because drug exposure determines its efficacy and toxicity, the question of whether H9 changes trastuzumab exposure in the body has been raised. Therefore, this study aimed to characterize trastuzumab pharmacokinetics and elucidate the effect of H9 on trastuzumab pharmacokinetics at a combination dose that shows synergism in mice. As a result, trastuzumab showed linear pharmacokinetics after its intravenous administration from 1 to 10 mg/kg. In the combination of trastuzumab and H9, single and 2-week treatments of oral H9 (500 mg/kg) did not influence trastuzumab pharmacokinetics. In the multiple-combination treatments of trastuzumab and H9 showing their synergistic effect (3 weeks of trastuzumab with 2 weeks of H9), the pharmacokinetic profile of trastuzumab was comparable to that of 3 weeks of trastuzumab alone. In tissue distribution, the tissue to plasma ratios of trastuzumab below 1.0 indicated its limited distributions within the tissues, and these patterns were unaffected by H9. These results suggest that the systemic and local exposures of trastuzumab are unchanged by single and multiple-combination treatments of H9.

Development of a Multiplex HIV/TB Diagnostic Assay Based on the Microarray Technology

Currently there are diagnostic tests available for human immunodeficiency virus (HIV) and tuberculosis (TB); however, they are still diagnosed separately, which can delay treatment in cases of co-infection. Here we report on a multiplex microarray technology for the detection of HIV and TB antibodies using p24 as well as TB CFP10, ESAT6 and pstS1 antigens on epoxy-silane slides. To test this technology for antigen-antibody interactions, immobilized antigens were exposed to human sera spiked with physiological concentrations of primary antibodies, followed by secondary antibodies conjugated to a fluorescent reporter. HIV and TB antibodies were captured with no cross-reactivity observed. The sensitivity of the slides was compared to that of high-binding plates. We found that the slides were more sensitive, with the detection limit being 0.000954 µg/mL compared to 4.637 µg/mL for the plates. Furthermore, stability studies revealed that the immobilized antigens could be stored dry for at least 90 days and remained stable across all pH and temperatures assessed, with pH 7.4 and 25 °C being optimal. The data collectively suggested that the HIV/TB multiplex detection technology we developed has the potential for use to diagnose HIV and TB co-infection, and thus can be developed further for the purpose.

Characteristics of Extracellular Vesicles from a High-Grade Serous Ovarian Cancer Cell Line Derived from a Platinum-Resistant Patient as a Potential Tool for Aiding the Prediction of Responses to Chemotherapy

Platinum-resistant high-grade serous ovarian cancer (HGSOC) is invariably a fatal disease. A central goal of ovarian cancer research is therefore to develop new strategies to overcome platinum resistance. Treatment is thus moving towards personalized therapy. However, validated molecular biomarkers that predict patients' risk of developing platinum resistance are still lacking. Extracellular vesicles (EVs) are promising candidate biomarkers. EpCAM-specific EVs are largely unexplored biomarkers for predicting chemoresistance. Using transmission electron microscopy, nanoparticle tracking analysis and flow cytometry, we compared the characteristics of EVs released from a cell line derived from a clinically confirmed cisplatin-resistant patient (OAW28) and EVs released from two cell lines from tumors sensitive to platinum-based chemotherapy (PEO1 and OAW42). We demonstrated that EVs released from the HGSOC cell line of chemoresistant patients exhibited greater size heterogeneity, a larger proportion of medium/large (>200 nm) Evs and a higher number of released EpCAM-positive EVs of different sizes, although the expression of EpCAM was predominant in EVs larger than 400 nm. We also found a strong positive correlation between the concentration of EpCAM-positive EVs and the expression of cellular EpCAM. These results may contribute to the prediction of platinum resistance in the future, although they should first be validated in clinical samples.

Cost effective and reliable cell based ELISA as an alternative method of flow cytometry for assessment of binding activity of Vedolizumab

Vedolizumab is a humanized monoclonal antibody used for inflammatory bowel disease treatment. Vedolizumab binds to the α4β7 integrin complex and inhibits its binding to mucosal addressin cell adhesion molecule-1 (MAdCAM-1). To evaluate the binding efficacy and quality control check of Vedolizumab, flow cytometry is performed by using HuT78 cells. As we know, flow cytometer is costly and require high equipment maintenance with a designated technical manpower to handle it. In this regard, the aim of study was to develop and validate an economical, simple and efficient cell based ELISA assay for potency estimation of Vedolizumab which has not been reported in any pharmacopoeia. The proposed bioassay method was optimized by investigating Vedolizumab binding to α4β7 integrin which is expressed by HuT78 cells. The validation of this method was done at different parameters including specificity, linearity, range, repeatability, precision, and accuracy. The Vedolizumab binding by ELISA results were found specific for Vedolizumab with linearity (R² = 0.99) and precision (%Geometric Coefficient of variance) observed for repeatability and intermediate precision were 3.38% and 2.6% respectively. The relative bias was calculated as 8.68% for repeated performances by different analysts and found in accordance with parameter of accuracy as per various pharmacopoeial guidelines. The developed method is established as robust, effective, and less expensive than high maintenance setup like flow cytometry based assay.

Pharmacokinetics of Trastuzumab After Subcutaneous and Intravenous Administration in Obese Patients

Background: Subcutaneous trastuzumab (T-SC) administration does not allow the historical target concentration of 20 µg/mL for efficacy to be reached, from the start of treatment in patients with a body mass index (BMI) >30 kg/m². Objectives: To analyze the influence of the strategy of dosification (fixed vs adjusted patient's body weight dose) on the initial minimum plasma concentration (C_min) of trastuzumab in obese patients. Methods: This was an observational, prospective study, which included patients with HER2-positive nonmetastatic breast cancer treated with trastuzumab. The determination of the C_min of trastuzumab was performed on day +21 of the first cycle using the ELISA technique. Patients were stratified according to the strategy of dosification and BMI. Results: A total of 50 patients were included; 16 patients received the drug intravenously and 34 in a fixed dosage subcutaneous (T-SC) regimen. The proportion of patients who achieved an adequate plasma concentration since the beginning of treatment was significantly higher when the drug was administered intravenously (93.8% vs 67.6%, P = 0.042). These differences are especially greater in T-SC patients with BMI >30 kg/m², with only 20% of patients exceeding the pharmacokinetic target. Conclusion and Relevance: Our study suggests that trastuzumab SC fixed dose of 600 mg is not equivalent to IV administration, especially in obese patients. An adequate trastuzumab exposure in this population needs patient weight-adjusted IV dosage in the first administration. The clinical relevance of these findings remains to be elucidated, and further research, including larger controlled trials, is warranted.

An Anticaffeine Antibody-Oligonucleotide Conjugate for DNA-Directed Immobilization in Environmental Immunoarrays

The development of fast and cheap high-throughput platforms for the detection of environmental contaminants is of particular importance to understand the human-related impact on the environment. The application of DNA-directed immobilization (DDI) of IgG molecules is currently limited to the clinical diagnostics scenario, possibly because of the high costs of production of such addressable platforms. We here describe the efficient and specific hybridization of an antibody-oligonucleotide conjugate to a short 12-mer capture probe. The specific antibody used is a monoclonal antibody against caffeine, a stimulant and important anthropogenic marker. With this work, we hope to contribute to broadening the application potential of DDI to environmental markers in order to develop cheaper and more stable high-throughput screening platforms for standard routine analysis of pollutants in a variety of complex matrices.

Simple and ultra-fast recognition and quantitation of compounded monoclonal antibodies: Application to flow injection analysis combined to UV spectroscopy and matching method

Compounding of monoclonal antibody (mAbs) constantly increases in hospital. Quality control (QC) of the compounded mAbs based on quantification and identification is required to prevent potential errors and fast method is needed to manage outpatient chemotherapy administration. A simple and ultra-fast (less than 30 s) method using flow injection analysis associated to least square matching method issued from the analyzer software was performed and evaluated for the routine hospital QC of three compounded mAbs: bevacizumab, infliximab and rituximab. The method was evaluated through qualitative and quantitative parameters. Preliminary analysis of the UV absorption and second derivative spectra of the mAbs allowed us to adapt analytical conditions according to the therapeutic range of the mAbs. In terms of quantitative QC, linearity, accuracy and precision were assessed as specified in ICH guidelines. Very satisfactory recovery was achieved and the RSD (%) of the intermediate precision were less than 1.1%. Qualitative analytical parameters were also evaluated in terms of specificity, sensitivity and global precision through a matrix of confusion. Results showed to be concentration and mAbs dependant and excellent (100%) specificity and sensitivity were reached within specific concentration range. Finally, routine application on "real life" samples (n = 209) from different batch of the three mAbs complied with the specifications of the quality control i.e. excellent identification (100%) and ± 15% of targeting concentration belonging to the calibration range. The successful use of the combination of second derivative spectroscopy and partial least square matching method demonstrated the interest of FIA for the ultra-fast QC of mAbs after compounding using matching method.

ELISA Development for Serum Hemeoxygenase-1 and Its Application to Patients with Acute Respiratory Distress Syndrome

Background

Hemeoxygenase-1 (HO-1) is an essential enzyme in heme catabolism and has been proposed as a biomarker of lung disease prognosis. We modified a commercial HO-1 enzyme-linked immunosorbent assay (ELISA) kit to achieve higher sensitivity and evaluated if serum HO-1 could be a biomarker to predict the prognosis of acute respiratory distress syndrome (ARDS) patients.

Methods

Serum samples were collected from 15 healthy volunteers to validate the modified ELISA. In the 22 patients with ARDS who were enrolled, serum HO-1 was measured upon diagnosis (D0) and at 7 days after diagnosis (D7).

Results

The serum HO-1 concentration could be measured in all healthy volunteers. The intra- and interassay tests and the percentage recovery test were acceptable. Compared with normal control subjects, patients with ARDS had significantly higher D0 HO-1 concentrations (75.4 ng/mL versus 31.7 ng/mL, P < 0.001). The 28-day survival was significantly better in patients with low D0 HO-1 (<75.8 ng/mL) than in those with high D0 HO-1 (≥75.8 ng/mL) (mortality rate: 18% versus 73%, P =0.016). Nonsurvivors had significantly higher D0 and D7 HO-1 concentrations than survivors (P < 0.05).

Conclusion

Serum HO-1 may be a useful biomarker to predict the prognosis of patients with ARDS.

Immunoassays for Measuring Serum Concentrations of Monoclonal Antibodies and Anti-biopharmaceutical Antibodies in Patients

Monoclonal antibodies (mAbs) may be used as biopharmaceuticals to treat various diseases, ranging from oncology to inflammatory and cardiovascular affections. Trustworthy analytical methods are necessary to study their pharmacokinetics, both during their development and in post-marketing studies. Because biopharmaceuticals are macromolecules, ligand-binding assays (both immunoassays and bioassays) are methods of choice to measure their concentrations. Immunoassays are based on the capture of biopharmaceuticals by their target, which may be a circulating or membrane antigen or by an antibody recognizing their structure. Bioassays measure the activity of the biopharmaceutical in a specific in vitro test. A number of techniques have been reported, but their limits of detection and quantification vary widely. Anti-drug antibodies (ADA) against biopharmaceuticals are often formed and sometimes interfere with clinical efficacy. Accurate and reliable detection of ADA is therefore necessary. Binding of ADA is dependent on affinity and avidity, which makes quantification challenging. In this review, we discuss the benefits and limitations of each method to determine mAb levels and carefully compare ADA assays.

Ultra-performance liquid chromatography/multiple reaction monitoring mass spectrometry quantification of trastuzumab in human serum by selective monitoring of a specific peptide marker from the antibody complementarity-determining regions

RATIONALE

Because of the large molecular weight, the structural complexity and the similarity with endogenous immunoglobulins present in high concentrations, in vivo quantitative studies with therapeutic monoclonal antibodies are particularly challenging. In this work, an UPLC/MRM MS-based methodology is described for the quantification of trastuzumab in human serum by monitoring a novel specific peptide marker located within its heavy chain Complementarity-Determining Region (CDR).

METHODS

For maximum sensitivity and selectivity, specific transitions of this diagnostic proteotypic peptide were optimized and monitored at m/z 364.1 → 437.3 (quantitation ion) and m/z 364.1 → 358.0 (confirmation ion). As a proof-of-concept, the methodology was applied to the determination of trastuzumab in human serum over a clinically relevant range from 0.02 to 200 μg/mL. The methodology has been evaluated in terms of specificity, linearity, accuracy, precision, detection and quantitation limits.

RESULTS

An excellent linear response has been obtained in the range from 0.036 to 3.6 fmol/μL for the standard peptide and from 0.03 to 285 fmol/μL for the trastuzumab in human serum with typical R² values of 0.99. The limit of detection (LOD) and limit of quantification (LOQ) are 0.005 fmol/μL and 0.05 fmol/μL, respectively, with mean bias and RSD values of 18% and 1%, respectively, for quality control samples.

CONCLUSIONS

The strategy used to set up the UPLC/MRM MS methodology based on monitoring specific peptide markers within CDRs can be potentially applied to the detection and quantification of other humanized or human mAbs in biological fluids. Copyright © 2017 John Wiley & Sons, Ltd.

Influence of Anthropometric Characteristics in Patients With Her2-Positive Breast Cancer on Initial Plasma Concentrations of Trastuzumab

Background: Plasma concentrations of trastuzumab <20 µg/mL in patients with gastric cancer are associated with reduced progression-free and overall survival. In breast cancer treatment, this relationship has not yet been studied, but a suboptimal pharmacodynamic exposure to trastuzumab could be a reason for therapeutic failure of treatment of HER2-positive breast cancer. Objective: The objective of the present study was to determine the proportion of nonmetastatic HER2-positive breast cancers that do not reach a minimum plasma concentration ( Cmin) of 20 µg/mL after first drug administration, established as therapeutically effective in clinical trials. The secondary objective was to identify the physiological and anthropometric characteristics that determine interindividual pharmacokinetic variability. Methods: Serum concentrations of trastuzumab were assessed by ELISA on day 1 of the second cycle before administration of the second dose ( Cmin). Results: Of 19 patients included, 9 (47.4%) had a mean Cmin of 19.0 µg/mL (±12.1) after the first administration. Body mass index (BMI) and weight was the main variable that determined the achievement of therapeutic levels after the first administration. Thus, the proportion of patients reaching the target concentration was 89% when BMI was ≤30 kg/m2 but only 11% when BMI was >30 kg/m2 ( P < 0.01). Conclusions: The standard dose of 600 mg subcutaneous trastuzumab did not ensure adequate pharmacodynamic exposure from the first administration in 52% of patients, with weight and BMI being related to the plasma levels obtained.

General Signal Amplification Strategy for Nonfaradic Impedimetric Sensing: Trastuzumab Detection Employing a Peptide Immunosensor

A label-free and reagent-free peptide mimotope capacitive biosensor has been developed for cancer drug (trastuzumab) quantification based on nonfaradic readout. The low sensitivity issue of capacitive biosensors was overcome with two innovations: peptide mimotope mixed self-assembled monolayer (SAM) biointerface and dilution of the analysis buffer. Signal amplification was achieved through dilution of phosphate-buffered saline (PBS) to tune C_dl to dominate the overall capacitance change upon target binding, which contribution is often negligible without dilution. After 1000× dilution, the limit of detection was lowered 500-fold (0.22 μg/mL) and the sensitivity was increased 20-fold [0.04192 (μg/mL)^-1] in comparison with undiluted PBS. The proposed signal amplification strategy is more straightforward and practical compared to biorecognition element engineering and other strategies. The proposed method was further applied to planar electrodes for optimizing sensing response time to less than 1 min.

Ionic Strength, Surface Charge, and Packing Density Effects on the Properties of Peptide Self-Assembled Monolayers

The various environmental parameters of packing density, ionic strength, and solution charge were examined for their effects on the properties of the immobilized peptide mimotope CH19 (CGSGSGSQLGPYELWELSH) that binds with the therapeutic antibody Trastuzumab (Herceptin) on a gold substrate. The immobilization of CH19 onto gold was examined with a quartz crystal microbalance (QCM). The QCM data showed the presence of intermolecular interactions resulting in the increase of viscoelastic properties of the peptide self-assembled monolayer (SAM). The CH19 SAM was diluted with CS7 (CGSGSGS) to decrease the packing density as CH19/CS7. The packing density and ionic strength parameters were evaluated by atomic force microscopy (AFM), ellipsometry, and QCM. AFM and ellipsometry showed a distinct conformational difference between CH19 and CH19/CS7, indicating a relationship between packing density and conformational state of the immobilized peptide. The CH19 SAM thickness was 40 Å with a rough topology, while the CH19/CS7 SAM thickness was 20 Å with a smooth topology. The affinity studies showed that the affinity of CH19 and CH19/CS7 to Trastuzumab were both on the order of 10⁷ M^-1 in undiluted PBS buffer, while the dilution of the buffer by 1000× increased both SAMs affinities to Trastuzumab to the order of 10¹⁵ M^-2 and changed the binding behavior from noncooperative to cooperative binding. This indicated that ionic strength had a more pronounced effect on binding properties of the CH19 SAM than packing density. Electrochemical impedance spectroscopy (EIS) was conducted on the CH19/CS7 SAM, which showed an increase in impedance after each EIS measurement cycle. Cyclic voltammetry on the CH19/CS7 SAM decreased impedance to near initial values. The impact of the packing density, buffer ionic strength, and local charge perturbation of the peptide SAM properties was interpreted based on the titratable sites in CH19 that could participate in the proton transfer and water equilibrium.

Development and use of specific ELISA methods for quantifying the biological activity of bevacizumab, cetuximab and trastuzumab in stability studies

Bevacizumab (BVZ), cetuximab (CTX) and trastuzumab (TTZ) are monoclonal antibodies (mAbs) used worldwide for the treatment of several widespread kinds of cancer. They are marketed as medicines under their respective tradenames: Avastin(®), Erbitux(®) and Herceptin(®). The aim of this research was to develop in-house specific enzyme-linked immunosorbent assays (ELISA) to assess the long-term stability of these three mabs. These assays assess the biological functionality of the mAbs by quantifying their biological activity. For this purpose, we developed an indirect ELISA procedure whereby the specific antigens against which the mAbs are directed are used as specific "capturing" antibodies on the ELISA plates. We therefore used vascular endothelial growth factor (VEGF) in the ELISA for BVZ; human epidermal growth factor receptor (hEGFR) in the ELISA for CTX and human receptor HER2 (hHER2) in the ELISA for TTZ. After the mAbs had attached to their antigen, we used an anti-human IgG (whole molecule) peroxidase-conjugate and o-phenylenediaminedihydrochloride substrate. The reaction was stopped using sulphuric acid and absorbance was recorded at a wavelength of 450nm. The three ELISA methods were validated in terms of calibration models, range of the assay, limits of detection and quantitation, intra and interday precision and accuracy, and specificity by cross reactions. Forced degradation studies were also conducted on the medicines, providing useful information. Finally, the proposed ELISA were successfully used in a long-term stability study to quantify the remaining biological activity in medicines that had been opened and then stored under two different storage conditions, i.e. refrigerated at 4°C and frozen at -20°C. Results indicated that BVZ (Avastin(®)) is the most stable of the three in terms of its biological functionality.

Characterization of Self-Assembled Monolayers of Peptide Mimotopes of CD20 Antigen and Their Binding with Rituximab

CD20, expressed in greater than 90% of B-lymphocytic lymphomas, is a target for antibody therapy. Rituximab is a chimeric therapeutic monoclonal antibody (mAb) against the protein CD20, allowing it to destroy B cells and to treat lymphoma, leukemia, transplant rejection, and autoimmune disorder. In this work, the binding of rituximab to self-assembled monolayers (SAMs) of peptide mimotopes of CD20 antigen was systematically characterized. Four peptide mimotopes of CD 20 antigen were selected from the literature and redesigned to allow their SAM immobilizations on gold electrodes through a peptide linker with cysteine. The bindings of these peptides with rituximab and control mAbs (trastuzumab and bevacizumab) were characterized by quartz crystal microbalance (QCM). Among the four peptide mimotopes initially selected, the peptide designated as CN-14 (CGSGSGSWPRWLEN) was the most selective and sensitive for rituximab binding. The CN-14 SAM was further characterized by ellipsometry and atomic force microscopy. The thickness of the CN-14 SAM film was approximately 32 Å, and the CN-14 SAM is suggested to be stabilized by a salt bridge of Arg-10 and Glu-13 between CN-14 peptides. The CN-14 salt bridge was evaluated by a series of modifications to the CN-14 peptide sequence and characterized by QCM. The CN-14 amide variant produced a better affinity to rituximab than CN-14 without a significant impact on selectivity. As the pKa of the Glu residue of CN-14 increased, the affinity of the SAM to rituximab increased, whereas the selectivity decreased. This was attributed to the weakening of the salt bridge between the CN-14 Arg-10 and Glu-13 at higher pKa values for Glu-13. Our study shows that peptide mimotopes have potential benefits in sensor applications, as the peptide-peptide interactions in the SAMs can be manipulated by the addition of functional groups to the peptide to influence the binding of target proteins.

A phase 1 study of a heterologous prime-boost vaccination involving a truncated HER2 sequence in patients with HER2-expressing breast cancer

A phase 1 clinical trial was conducted to assess the safety, tolerability, and preliminary efficacy of a heterologous prime-boost strategy involving plasmid DNA (pHM-GM-CSF, expressing truncated human epidermal growth factor receptor 2 (HER2) and granulocyte macrophage colony-stimulation factor (GM-CSF) as a bicistronic message) and an adenoviral vector (Ad-HM, containing the same modified HER2 sequence only), in patients with stage III–IV metastatic breast cancer expressing HER2. Nine eligible subjects were divided into three cohorts based on the dosages (2, 4, and 8 mg/patient/visit) of pHM-GM-CSF used as the primer, which was intramuscularly injected three times at weeks 0, 2, and 4. It was followed by a single injection of Ad-HM (3 × 10⁹ virus particles), used as a booster, at week 6. During the 6-month follow-up period, adverse events (AEs), pharmacokinetics and pharmacodynamics, and HER2-specific cellular and humoral immune responses were evaluated. Seven cases of minor grade 1 toxicities in four of nine subjects and no serious drug-related AEs were reported. HER2-specific cell-mediated or humoral immunity was produced in all (100%) or three subjects (33%), respectively. One subject showed a partial response, and seven subjects had stable diseases. However, there were no differences in clinical tumor response and HER2-specific immune responses among the cohorts. These results showed that intramuscular injections of pHM-GM-CSF and Ad-HM were well tolerated and safe.

Quantification of an intact monoclonal antibody, rituximab, by (RP)HPLC/DAD in compliance with ICH guidelines

We studied the quantification of an intact therapeutic monoclonal antibody (mAb), rituximab (RTX), using (reversephase) high-performance liquid chromatography with diode array detection ((RP)HPLC/DAD). To this end, we developed a chromatographic method and validated it as stabilityindicating in accordance with the International Conference on Harmonization guidelines (ICH). A 300-Å C8 column (250 mm×4.6 mm, 5 μm) was used to perform the analysis, and the temperature was maintained at 70 °C. Although only one mAb was analyzed, it was necessary to apply a gradient to elute it with a complex organic mixture. Chromatograms were registered at several wavelengths, with λ =214 nm employed for quantification purposes. The method was developed to quantify marketed RTX under typical hospital administration conditions. Further dilution was avoided in order to prevent additional mAb modification, and in this way the method was shown to be linear from 60 to 5000 mg/L. The precision of the method (repeatability and intermediate precision, estimated as the relative standard deviation, RSD %), was less than 1.0 %. Accuracy, specificity, robustness, and system suitability were also evaluated as specified in the ICH guidelines.We conducted a comprehensive chromatographic analysis by submitting RTX to several informative stress conditions. These forced degradation studies were conducted for two reasons: to estimate the specificity of the method, and to evaluate the robustness of the mAb formulation against external stress factors when handling it in preparation for administration. Thus, we investigated the effects of acid, base, oxidation, ionic strength, temperature, and UV light. Although a slight modification to the intact mAb could not be distinguished chromatographically in the stress studies we conducted, the procedure proposed here to evaluate peak purity enabled us to detect it with a satisfactory level of confidence. The proposed method could therefore be considered stability-indicating for quantyfying the intact mAb since it is qualified to detect its degradation/modification. Finally, the method was used to evaluate RTX in a long-term stability study performed under hospital conditions of use.

Quality control and stability studies with the monoclonal antibody, trastuzumab: application of 1D- vs. 2D-gel electrophoresis

Recombinant monoclonal antibodies (rmAbs) are medicinal products obtained by rDNA technology. Consequently, like other biopharmaceuticals, they require the extensive and rigorous characterization of the quality attributes, such as identity, structural integrity, purity and stability. The aim of this work was to study the suitability of gel electrophoresis for the assessment of charge heterogeneity, post-translational modifications and the stability of the therapeutic, recombinant monoclonal antibody, trastuzumab. One-dimensional, SDS-PAGE, under reducing and non-reducing conditions, and two-dimensional gel electrophoresis were used for the determination of molecular mass (Mr), the isoelectric point (pI), charge-related isoform patterns and the stability of trastuzumab, subjected to stressed degradation and long-term conditions. For the assessment of the influence of glycosylation in the charge heterogeneity pattern of trastuzumab, an enzymatic deglycosylation study has been performed using N-glycosidase F and sialidase, whereas carboxypeptidase B was used for the lysine truncation study. Experimental data documented that 1D and 2D gel electrophoresis represent fast and easy methods to evaluate the quality of biological medicinal products. Important stability parameters, such as the protein aggregation, can be assessed, as well.

Identification and quantification of a new family of peptide endocannabinoids (Pepcans) showing negative allosteric modulation at CB1 receptors

The α-hemoglobin-derived dodecapeptide RVD-hemopressin (RVDPVNFKLLSH) has been proposed to be an endogenous agonist for the cannabinoid receptor type 1 (CB(1)). To study this peptide, we have raised mAbs against its C-terminal part. Using an immunoaffinity mass spectrometry approach, a whole family of N-terminally extended peptides in addition to RVD-Hpα were identified in rodent brain extracts and human and mouse plasma. We designated these peptides Pepcan-12 (RVDPVNFKLLSH) to Pepcan-23 (SALSDLHAHKLRVDPVNFKLLSH), referring to peptide length. The most abundant Pepcans found in the brain were tested for CB(1) receptor binding. In the classical radioligand displacement assay, Pepcan-12 was the most efficacious ligand but only partially displaced both [(3)H]CP55,940 and [(3)H]WIN55,212-2. The data were fitted with the allosteric ternary complex model, revealing a cooperativity factor value α < 1, thus indicating a negative allosteric modulation. Dissociation kinetic studies of [(3)H]CP55,940 in the absence and presence of Pepcan-12 confirmed these results by showing increased dissociation rate constants induced by Pepcan-12. A fluorescently labeled Pepcan-12 analog was synthesized to investigate the binding to CB(1) receptors. Competition binding studies revealed K(i) values of several Pepcans in the nanomolar range. Accordingly, using competitive ELISA, we found low nanomolar concentrations of Pepcans in human plasma and ∼100 pmol/g in mouse brain. Surprisingly, Pepcan-12 exhibited potent negative allosteric modulation of the orthosteric agonist-induced cAMP accumulation, [(35)S]GTPγS binding, and CB(1) receptor internalization. Pepcans are the first endogenous allosteric modulators identified for CB(1) receptors. Given their abundance in the brain, Pepcans could play an important physiological role in modulating endocannabinoid signaling.

Immobilization of a human epidermal growth factor receptor 2 mimotope-derived synthetic peptide on Au and its potential application for detection of herceptin in human serum by quartz crystal microbalance

Therapeutic antibodies are antigenically similar to human antibodies and are difficult to detect in assays of human serum samples without the use of the therapeutic antibody's complementary antigen. Herein for the first time, we established a platform to detect Herceptin in solutions by using a small (<2.2 kDa), inexpensive, highly stable human epidermal growth factor receptor (HER2) mimotope-derived synthetic peptide immobilized on the surface of a Au quartz electrode. We used the HER2 mimotope as a substitute for the HER2 receptor protein in piezoimmunosensor or quartz crystal microbalance (QCM) assays to detect Herceptin in human serum. We demonstrated that assay sensitivity was dependent upon the amino acids used to tether and link the peptide to the sensor surface and the buffers used to carry out the assays. The detection limit of the piezoimmunosensor assay was 0.038 nM with a linear operating range of 0.038-0.859 nM. Little nonspecific binding to other therapeutic antibodies (Avastin and Rituxan) was observed. Levels of Herceptin in serum samples obtained from treated patients, as ascertained using the synthetic peptide-based QCM assay, were typical for those treated with Herceptin. The findings of this study are significant in that low-cost synthetic peptides could be used in a QCM assay, in lieu of native or recombinant antigens or capture antibodies, to rapidly detect a therapeutic antibody in human serum. The results suggested that a synthetic peptide bearing a particular functional sequence could be applied for developing a new generation of affinity-based immunosensors to detect a broad range of clinical biomarkers.

In vitro synthesis of primary specific anti-breast cancer antibodies by normal human peripheral blood mononuclear cells

In this study, we developed a unique in vitro model to mimic the endogenous tumor microenvironment to understand the effect of immunotherapy with activated T-cells (ATC) armed with anti-CD3 × anti-Her2 bispecific antibody (aATC) on antibody response by naive immune cells. This model contained a co-culture of naïve peripheral blood mononuclear cells (PBMC), breast cancer cells (SK-BR-3), ATC or aATC and CpG ODNs. Culture supernatants were tested at various time points for anti-SK-BR-3 antibodies by ELISA, Western blot and flow cytometry. PBMC cocultured with non-irradiated aATC or irradiated (*) aATC showed significant increases in anti-tumor antibody production at day 14 (P < 0.0001) in the presence of CpG-ODN compared to unstimulated PBMC cultures (n = 9). Antibody specificity was confirmed by ELISA, Western blot and flow cytometry. Co-cultures containing *aATC and CpG showed significantly enhanced levels of IgG(2) (P < 0.001) and cytokines that promote IgG(2) synthesis including IL-13 (P < 0.02), IFNγ (P < 0.01) and GM-CSF (P < 0.05) compared to unstimulated PBMC control (n = 3). We show that aATC targeting and lysis of tumor cells induces an anti-tumor antibody response in our in vitro model. This model provides a unique opportunity to evaluate the interactions of T-cells, B-cells, and antigen-presenting cells leading to specific anti-tumor antibody responses.

Tumour exosomes inhibit binding of tumour-reactive antibodies to tumour cells and reduce ADCC

In order to grow within an immunocompetent host, tumour cells have evolved various strategies to cope with the host's immune system. These strategies include the downregulation of surface molecules and the secretion of immunosuppressive factors like IL-10 and PGE2 that impair the maturation of immune effector cells, among other mechanisms. Recently, tumour exosomes (TEX) have also been implicated in tumour-induced immune suppression as it has been shown that TEX can induce apoptosis in T lymphocytes. In this study, we extend our knowledge about immunosuppressive features of these microvesicles in that we show that TEX efficiently bind and sequester tumour-reactive antibodies and dramatically reduce their binding to tumour cells. Moreover, we demonstrate that this antibody sequestration reduces the antibody-dependent cytotoxicity by immune effector cells, which is among the most important anti-tumour reactions of the immune system and a significant activity of therapeutic antibodies. Taken together, these data point to the fact that tumour-derived exosomes interfere with the tumour-specific function of immune cells and constitute an additional mechanism how tumours escape from immune surveillance.

Development, validation and application of ELISAs for pharmacokinetic and HACA assessment of a chimeric anti-CD40 monoclonal antibody in human serum

As part of a Phase I chimeric anti-CD40 monoclonal antibody clinical trial, two enzyme-linked immunosorbent assays (ELISAs) were developed for secondary endpoints: 1) for the pharmacokinetic (PK) monitoring of serum antibody levels and 2) for immunogenic screening of human anti-chimeric antibody (HACA) responses. The ELISA is a well established immunoassay, with clear guidelines for validation when used as a quantitative assay. However, these parameters may not always be relevant for a semi-quantitative assay used to assess whether a sample is positive or negative for a novel marker such as an antibody developed against a therapeutic antibody. We report here the development of a quantitative PK ELISA and a semi-quantitative HACA ELISA, and the different approaches of validation to prove each assay are 'fit for purpose.' The parameters of linearity (R²>0.99), accuracy (±30%), lowest level of detection (4 μg/ml), intra-assay (coefficient of variation (CV) <20%) and inter-assay (CV<20%) variability were assessed for the quantitative PK assay. For the semi-quantitative HACA assay, parameters of linearity (R²>0.99), lowest level of detection, intra (CV<10%) and inter-assay (CV<30%) variability were assessed using a surrogate positive control. The validation outcome showed that each assay was robust, reliable and accurate to meet the requirements of the intended analytical application, that being to 1) quantitatively determine the concentration of antibody in the serum and 2) determine whether a sample is positive or negative for human anti-chimeric antibodies. Each assay has been successfully translated for use in a clinical trial with adequate quality controls and acceptance criteria set for monitoring consistency and performance.

Therapeutic monoclonal antibody concentration monitoring: free or total?

Most therapeutic monoclonal antibodies are designed to bind a specific antigen to elicit pharmacological effects. Accurate quantification of a therapeutic monoclonal antibody in biological matrices is essential for assessing its pharmacokinetics and selecting an effective dosing regimen. Therapeutic antibodies may exist in free, partially bound and fully bound forms in the bloodstream. The choice of which form(s) to measure and how to measure them is gaining much attention with the increase in the number of soluble therapeutic targets. This article will review the bioanalytical methods used in supporting the clinical development of the US FDA-approved therapeutic monoclonal antibodies and also discuss how different factors, such as assay format, target and antibody concentrations, and sample dilutions, can have an impact on the measurement of each form of antibody. Appreciation of which form of drug is being measured and what factors may impact measurement under different conditions are important for interpretation of the pharmacokinetics of therapeutic antibodies.

A general process for the development of peptide-based immunoassays for monoclonal antibodies

Purpose

Monoclonal antibodies (mAb) are an important and growing class of cancer therapeutics, but pharmacokinetic analyses have in many cases been constrained by the lack of standard and robust pharmacologic assays. The goal of this project was to develop a general method for the production of immunoassays that can measure the levels of therapeutic monoclonal antibodies in biologic samples at relevant concentrations.

Methods

Alemtuzumab and rituximab are monoclonal approved for the treatment of B-cell malignancies and were used as a model system. Phage-displayed peptide libraries were screened for peptide sequences recognized by alemtuzumab (anti-CD52) or rituximab (anti-CD20). Synthetic biotinylated peptides were used in enzyme-linked immunosorbent assays (ELISA). Peptides directly synthesized on polymer resin beads were used in an immunofluorescent-based assay.

Results

Peptide mimetope sequences were recovered for both mAb and confirmed by competitive staining and kinetic measurements. A peptide-based ELISA method was developed for each. The assay for rituximab had a limit of detection of 4 μg/ml, and the assay for alemtuzumab had a limit of detection of 1 μg/ml. Antibody-specific staining of peptide conjugated beads could be seen in a dose-dependent manner.

Conclusion

Phage-displayed peptide libraries can be a source of highly specific mimetopes for therapeutic mAb. The biotinylated forms of those peptides are compatible with conventional ELISA methods with sensitivities comparable to other assay methods and sufficient for pharmacological studies of those mAb given at high dose. The process outlined here can be applied to any mAb to enable improved pharmacokinetic analysis during the development and clinical use of this class of therapies.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-009-1240-1) contains supplementary material, which is available to authorized users.

Development and validation of cell-based ELISA for the quantification of trastuzumab in human plasma

Trastuzumab is a therapeutic monoclonal antibody against the Her2 oncoprotein, which is over-expressed in approximately 30% of breast cancers, and is now used routinely in the management of early and metastatic Her2+ disease. However, not all Her2+ breast cancer patients respond to trastuzumab and the pharmacodynamic and pharmacokinetic parameters behind this variation in response are unknown. Pharmacological investigations into variable response to trastuzumab have been hampered by the lack of a published feasible method to determine trastuzumab concentration in plasma. Here we describe the development and validation of a cell-based ELISA to measure trastuzumab in human plasma. The assay specifically measures the interaction between trastuzumab and Her2 and has a dynamic range of between 10 and 120 microg/ml. The mean intra-assay and inter-assay variability of the ELISA was 9%. Trastuzumab in plasma was stable for at least 10 weeks at -20 degrees C and 72 h at 4 degrees C, and was unaffected by 5 freeze/thaw cycles. Having validated the assay, the trough plasma trastuzumab concentrations of 30 patients being treated for metastatic or early disease were measured. The median trough concentration was 62 (range 21 to 441) microg/ml. This cell-based ELISA method has undergone appropriate validation and is suitable for quantification of trastuzumab in the plasma of patients treated with Herceptin.

Antibody detection employing sol-gel immobilized parasites

Immunofluorescence assay (IFA) and immunoperoxidase assay (IPA) are useful diagnostic techniques for specific antibody detection for different diseases. Both involve several alternatives for immobilization of cells, such as solvent or heat fixation. Non-covalent immobilization implies rigorous storage conditions at -20 degrees C to preserve the slides, and usually numerous cells are detached during the washing steps, which can lead to inconsistencies in the results. Sol-gel chemistry is usually used for coating different materials because of the mild conditions of the polymerization reaction and the ability to introduce functional groups to a wide variety of surfaces. We have developed a novel procedure for the attachment of Trypanosoma cruzi epimastigotes and Leishmania guyanensis promastigotes to a silicon oxide polymer covered glass surface. The film was prepared using standard microscope slides with tetraethoxysilane and 3-aminopropyl triethoxysilane as polymeric precursors. When acetone was used as the major coating solvent, the IFA showed the fluorescence of the attached parasites without matrix background interference. Similar results were observed when the IPA was evaluated. The sensitivity and specificity of the sol-gel immobilized parasite slides were comparable with the heat fixation technique. The performance of the coated slides was maintained for at least 2 months at 4 degrees C storage temperature. This immobilization method does not affect the molecular epitopes of the attached cells. Thus, homogeneous, ready to use, long lasting coated slides were obtained, which are appropriate for field conditions.

Scalable fabrication of immunosensors based on carbon nanotube polymer composites

In this work we present the fabrication and characterization of immunosensors based on polystyrene (PS)-multiwalled carbon nanotube (MWCNT) composites. The electrochemical properties of the sensors have been investigated and show that the surface area is increased upon addition of the MWCNT-PS layer. Furthermore, a plasma activation process is used to partially remove the PS and expose the MWCNTs. This results in a huge increase in the electrochemical area and opens up the possibility of binding biomolecules to the MWCNT wall. The MWCNTs have been functionalized covalently with a model antibody (rabbit IgG). The biosensors have been tested using amperometric techniques and show detection limits comparable to standard techniques such as ELISA.

Herceptin

The biology of the human epidermal growth factor (EGF) receptor-2 (HER2) has been reviewed numerous times and provides an excellent example for developing a targeted cancer therapeutic. Herceptin, the FDA-approved therapeutic monoclonal antibody against HER2, has been used to treat over 150,000 women with breast cancer. However, the developmental history of Herceptin, the key events within the program that created pivotal decision points, and the reasons why decisions were made to pursue the monoclonal antibody approach have never been adequately described. The history of Herceptin is reviewed in a way which allows the experience to be shared for the purposes of understanding the drug discovery and development process. It is the objective of this review to describe the pivotal events and explain why critical decisions were made that resulted in the first therapeutic to successfully target tyrosine kinases in cancer. New approaches and future prospects for therapeutics targeting the HER family are also discussed.

A rapid and sensitive ELISA to quantify an HBsAg specific monoclonal antibody and a plant-derived antibody during their downstream purification process

An enzyme-linked immunosorbent assay to quantify the mAb CB.Hep-1 during downstream purification process was standardized and validated. This assay is characterized by a short time of incubation at high temperature, allowing the detection of this antibody with high specificity and sensitivity. Detection of antigen-antibody reaction was achieved using a horseradish peroxidase conjugated anti-mouse IgG whose enzyme activity was revealed with o-phenylenediamine substrate. The immunoassay is linear in a range between 3.12 and 50 ng/mL, with a recovery of 98.55-107.62%. According to results, it is possible to estimate the mAb CB.Hep-1 concentration with high precision and reproducibility. The intra- and interassay coefficient of variation ranged from 0.25 to 8.64% and 1.84 to 9.43%, respectively. Significant differences were not observed in the plant-derived antibody quantification by HRP-ELISA and PhoA-ELISA (n=18), demonstrating that plant endogenous peroxidases do not produce interferences in the quantification of this molecule. Therefore, both antibodies can be tested with the same immunoassay with high precision, specificity and accuracy during their respective purification processes without interference of the buffers and sample characteristics.

Immunologic quantitation of tissue factors

The large number of conflicting reports on the presence and concentration of circulating tissue factor (TF) in blood generates uncertainties regarding its relevance to hemostasis and association with specific diseases. We believe that the source of these controversies lies in part in the assays used for TF quantitation. We have developed a highly sensitive and specific double monoclonal antibody fluorescence-based immunoassay and integrated it into the Luminex Multi-Analyte Platform. This assay, which uses physiologically relevant standard and appropriate specificity controls, measures TF antigen in recombinant products and natural sources including placenta, plasma, cell lysates and cell membranes. Comparisons of reactivity patterns of various full-length and truncated TFs on an equimolar basis revealed quantitative differences in the immune recognition of TFs by our antibodies in the order of TF 1-263 > 1-242 > 1-218 > placental TF. Despite this differential recognition, all TF species are quantifiable at concentrations < or = 2 pM. Using a calibration curve constructed with recombinant TF 1-263 and plasma from healthy individuals (n = 91), we observed the concentration of TF antigen in plasma to be substantially lower than that generally reported in the literature: TF antigen in plasma of 72 individuals (79%) was below 2 pM (quantitative limit of our assay); TF antigen levels between 2.0 and 5.0 pM could be detected in six individuals (7%); and in 14% (13 plasmas), the non-specific signal was higher than the specific signal, and thus TF levels could not be determined. These differential recognition patterns affect TF quantitation in plasma and should be considered when evaluating plasma TF-like antigen concentrations.