Detection of rViscumin in plasma samples by immuno-PCR

The Anti-Inflammatory Activity of Viscum album

The therapeutic story of European mistletoe (Viscum album L.) presents a seesawing profile. In ancient times, this hemiparasitic plant was considered a panacea and even to be endowed with exceptional beneficial properties. In more recent times, despite its multiple uses in traditional medicines, some parts of the plant, in particular the berries, were considered poisonous and dangerous, including concerns of cytotoxicity, which spread serious suspicion on its medicinal utility. However, since the last century, medical interest in mistletoe has come back in force due to its utilization in clinical cancer treatments, based on its selective action on tumor cells. In Central Europe, the hydro-alcoholic extracts of European mistletoe register a relevant and continuous utilization in anthroposophic medicine, which is a holistic system that includes the utilization of phytomedicinal substances. In Switzerland and Germany, most physicians and patients use these products as complementary therapy in oncological treatments. However, despite its increasing use in this field, the results of mistletoe's use are not always convincing, and other aspects have appeared. Nowadays, products that contain mistletoe are utilized in several fields, including diet, phytotherapy, veterinary medicine and homeopathy, but in particular in cancer therapies as coadjuvant factors, in consideration of several positive effects including effects in the improvement of quality-of-life conditions and reinforcement of the immune system. In this review, based on the understanding of the association between cancer and inflammation, we propose a relationship between these recent uses of mistletoe, based on its antioxidant properties, which are supported by phytochemical and pharmacological data. The unicity of mistletoe metabolism, which is a direct consequence of its hemiparasitism, is utilized as a key interpretation element to explain its biological properties and steer its consequent therapeutic uses.

Bioanalytical strategies in drug discovery and development

A reliable, rapid, and effective bioanalytical method is essential for the determination of the pharmacokinetic, pharmacodynamic, and toxicokinetic parameters that inform the safety and efficacy profile of investigational drugs. The overall goal of bioanalytical method development is to elucidate the procedure and operating conditions under which a method can sufficiently extract, qualify, and/or quantify the analyte(s) of interest and/or their metabolites for the intended purpose. Given the difference in the physicochemical properties of small and large molecule drugs, different strategies need to be adopted for the development of an effective and efficient bioanalytical method. Herein, we provide an overview of different sample preparation strategies, analytical platforms, as well as procedures for achieving high throughput for bioanalysis of small and large molecule drugs.

Design and validation of an immuno-PCR assay for IFN-α2b quantification in human plasma

Aim: Nowadays, IFN-α is considered a promising therapeutic target for systemic lupus erythematosus. An immuno-PCR (iPCR) was developed to quantify low amounts of IFN-α in human plasma followed by a deep analysis of the methodologic robustness throughout quality by design approach. Results: An accurate, sensitive, selective and versatile iPCR was validated. The critical iPCR procedural steps were identified, applying a Plackett–Burman design. Also, this assay demonstrated an outstanding LOD of 0.3 pg/ml. A significant aspect relies on its high versatility to detect and quantify other cytokines in human plasma as the appropriate biotinylated antibody is employed. Conclusion: This reliable iPCR assay can be clinically used as an alternative method for quantitating and detecting low IFN-α2b concentrations in human plasma samples.

Sensitive and high throughput quantification of abscisic acid based on quantitative real time immuno-PCR

BACKGROUND

Abscisic acid (ABA) functions as a stress phytohormone in many growth and developmental processes in plants. The ultra-sensitive determination of ABA would help to better understand its vital roles and action mechanisms.

RESULTS

We report a new sensitive and high throughput quantitative real time immuno-PCR (qIPCR) method based on biotin-avidin linkage system for ABA determination in plants. ABA monoclonal antibody (McAb) coated on the inner surface of PCR well pretreated with glutaraldehyde. The pre-prepared probe complex, including biotinylated McAb, biotinylated DNA and streptavidin linker, was convenient for high throughput operations. Finally, probe DNA was quantified by real-time PCR. The detectable ranges were from 10 to 40 ng/L with a limit of detection (LOD) of 2.5 fg. ABA contents in plant sample were simultaneously analyzed using LC-MS/MS to validate the qIPCR method. The results showed that qIPCR method has good specificity and repeatability with a recovery rate of 96.9%.

CONCLUSION

The qIPCR method is highly sensitive for ABA quantification for actual plant samples with an advantage of using crude extracts instead of intensively purified samples.

Multiplexed In-cell Immunoassay for Same-sample Protein Expression Profiling

In-cell immunoassays have become a valuable tool for protein expression analysis complementary to established assay formats. However, comprehensive molecular characterization of individual specimens has proven challenging and impractical due to, in part, a singleplex nature of reporter enzymes and technical complexity of alternative assay formats. Herein, we describe a simple and robust methodology for multiplexed protein expression profiling on the same intact specimen, employing a well-characterized enzyme alkaline phosphatase for accurate quantification of all targets of interest, while overcoming fundamental limitations of enzyme-based techniques by implementing the DNA-programmed release mechanism for segregation of sub-sets of target-bound reporters. In essence, this methodology converts same-sample multi-target labeling into a set of isolated singleplex measurements performed in a parallel self-consistent fashion. For a proof-of-principle, multiplexed detection of three model proteins was demonstrated on cultured HeLa cells, and two clinically-relevant markers of dementia, β-amyloid and PHF-tau, were profiled in formalin-fixed paraffin embedded brain tissue sections, uncovering correlated increase in abundance of both markers in the “Alzheimer’s disease” cohort. Featuring an analytically powerful yet technically simple and robust methodology, multiplexed in-cell immunoassay is expected to enable insightful same-sample protein profiling studies and become broadly adopted in biomedical research and clinical diagnostics.

Application of carbon nanotubes layered on silicon wafer for the detection of breast cancer marker carbohydrate antigen 15-3 by immuno-polymerase chain reaction

A highly sensitive detection of breast cancer marker, carbohydrate antigen 15-3 (CA 15-3) by carbon nanotube (CNT) based immuno-polymerase chain reaction was reported. The study was aimed to develop a precise and sensitive method to diagnose breast cancer and its recurrence. The hydrofluoric acid (HF) treated silicon wafer layered with bundled CNT was used as the substrate. The surface was treated with HNO3/H2SO4 to graft carboxyl groups on the tips of CNT. Subsequently, polyoxyethylene bis-amine was grafted to conjugate anti human CA 15-3 antibodies. Water contact angle measurement, scanning electron microscope, Fourier transform infrared spectrometer, Raman spectrometer and sodium dodecyl sulfate polyacrylamide gel electrophoresis were employed to confirm the surface modification. The captured antibodies on the CNT were used to capture the target antigen CA 15-3 and the biotinylated secondary antibodies were subsequently bound with the target antigen. A bi-functional streptavidin was used to link biotinylated DNA to the biotinylated detection antibodies. The biotinylated target DNA was amplified by PCR, and then analyzed by agarose gel electrophoresis. The lower limit of detection of CA 15-3 by the proposed immuno-PCR system was 0.001 U/mL, which is extremely sensitive than the other bioanalytical techniques.

Pharmacokinetics of natural mistletoe lectins after subcutaneous injection

PURPOSE

Knowledge of natural mistletoe lectins (nML) pharmacokinetics can be regarded as essential for further rational studies with mistletoe preparations. Studies with intravenous application of a recombinant type II ribosome inactivating protein (rML) analogous to nML revealed a short half-life of about 13 min in cancer patients. This open-label, phase I, monocenter clinical trial was performed in order to describe the pharmacokinetics of nML.

METHODS

In 15 healthy male volunteers aged 18-42 years, nML were detected with a modified sandwich immuno-polymerase chain reaction (PCR) technique (Imperacer, Chimera Biotec) after single subcutaneous injection of a mistletoe extract (abnobaVISCUM(R) Fraxini 20 mg) with marketing authorization containing about 20 microg nML/ml. Secondary objectives were safety and the number of activated natural killer cells (CD54(+)/CD94(+)).

RESULTS

In none of the volunteers were nML detectable before the injection, and in all volunteers, nML were detected in serum samples after injection. Individual variability, however, was large. Mean and median peak concentrations were reached 1 and 2 h after injection, respectively. In some volunteers, nML were still detectable at the final investigation 2 weeks after injection. The injection resulted in fever and flu-like symptoms in all volunteers, but no serious adverse events occurred. All symptoms and local reactions at the injection site completely disappeared within a range of 4-95 days. The number of activated natural killer (NK) cells did not change.

CONCLUSIONS

Natural ML from abnobaVISCUM Fraxini 20 mg are detectable in serum after a single subcutaneous injection. Detectability is considerably longer compared with intravenously administered rML. The subcutaneous injection of this preparation without usual pretreatment with lower doses results in short-lasting fever and other flu-like symptoms.

Phase I trial of r viscumin (INN: aviscumine) given subcutaneously in patients with advanced cancer: a study of the European Organisation for Research and Treatment of Cancer (EORTC protocol number 13001)

Safety of aviscumine by subcutaneous route was assessed in patients with advanced cancer refractory to chemotherapy. Patients with progressive disease received escalating doses twice weekly. Treatment of the accrued 26 patients (10 colorectal cancer (CRC), 6 soft tissue sarcoma (STS), 5 melanoma (MM), 5 others) was well tolerated without substance-related grade 3 or 4 toxicities. Grade 1/2 toxicities were predominantly injection site reactions. Aviscumine lacked dose-limiting toxicity (DLT) up to a maximal dose of 10 ng/kg. An increase of interleukin-1 beta and interferon-gamma from baseline was seen in the patient's plasma between the 1st and 11th injection. Highest release of both cytokines was in the dose range of 4-5.9 ng/kg. Interferon-gamma was not detected after doses higher than 6 ng/kg. Eight patients (5 CRC, 1 MM, 1 STS, 1 RCC) had disease stabilisation for 79-250 days (median122 days) associated with an increase of interleukin (IL)-1 beta and interferon (IFN)-gamma. Aviscumine was well tolerated and appeared to possess clinical activity at a biologically active dose between 4 and 6 ng/kg.

Sensitivity by combination: immuno-PCR and related technologies

The versatility of immunoassays for the detection of antigens can be combined with the signal amplification power of nucleic acid amplification techniques in a broad range of innovative detection strategies. This review summarizes the spectrum of both, DNA-modification techniques used for assay enhancement and the resulting key applications. In particular, it focuses on the highly sensitive immuno-PCR (IPCR) method. This technique is based on chimeric conjugates of specific antibodies and nucleic acid molecules, the latter of which are used as markers to be amplified by PCR or related techniques for signal generation and read-out. Various strategies for the combination of antigen detection and nucleic acid amplification are discussed with regard to their laboratory analytic performance, including novel approaches to the conjugation of antibodies with DNA, and alternative pathways for signal amplification and detection. A critical assessment of advantages and drawbacks of these methods for a number of applications in clinical diagnostics and research is conducted. The examples include the detection of viral and bacterial antigens, tumor markers, toxins, pathogens, cytokines and other targets in different biological sample materials.

Detecting antigens by quantitative immuno-PCR

The quantitative immuno-PCR (qIPCR) technology combines the advantages of flexible and robust immunoassays with the exponential signal amplification power of PCR. The qIPCR allows one to detect antigens using specific antibodies labeled with double-stranded DNA. The label is used for signal generation by quantitative PCR. Because of the efficiency of nucleic acid amplification, qIPCR typically leads to a 10- to 1,000-fold increase in sensitivity compared to an analogous enzyme-amplified immunoassay. A standard protocol of a qIPCR assay to detect human interleukin 6 (IL-6) using a sandwich immunoassay combined with real-time PCR readout is described here. The protocol includes initial immobilization of the antigen, and coupling of this antigen with antibody-DNA conjugates is then carried out by (a) the stepwise assembly of biotinylated antibody, streptavidin and biotinylated DNA, (b) the use of a biotinylated antibody and an anti-biotin-DNA conjugate or (c) the employment of an anti-IL-6 antibody-DNA conjugate. Following the assembly of signal-generating immunocomplexes, real-time PCR is used to amplify and record the signal. Depending on the coupling strategy, the qIPCR assays require 4-7 h with only about 3 h hands-on-time. The use of qIPCR assays enables the detection of rare biomarkers in complex biological samples that are poorly accessible by conventional immunoassays. Therefore, qIPCR offers novel opportunities for the biomedical analysis of, for instance, neurodegenerative diseases and viral infections as well as new tools for the development of novel pharmaceuticals.

Ultrasensitive assays for proteins

Proteins are essential components of organisms and are involved in a wide range of biological functions. There are increasing demands for ultra-sensitive protein detection, because many important protein biomarkers are present at ultra-low levels, especially during the early stages of disease. Measuring proteins at low levels is also crucial for investigations of the protein synthesis and functions in biological systems. In this review, we summarize the recent developments of novel technology enabling ultrasensitive protein detection. We focus on two groups of techniques that involve either polymerase amplification of affinity DNA probes or signal amplification by the use of nano-/micro-materials. The polymerase-based amplification of affinity DNA probes indirectly improves the sensitivity of protein detection by increasing the number of detection molecules. The use of nano-/micro-materials conjugated to affinity probes enhances the measurement signals by using the unique electrical, optical, and catalytic properties of these novel materials. This review describes the basic principles, performances, applications, merits, and limitations of these techniques.

Magneto immuno-PCR: a novel immunoassay based on biogenic magnetosome nanoparticles

We describe an innovative modification of the Immuno-PCR technology for automatable high sensitive antigen detection. The Magneto Immuno-PCR (M-IPCR) is based on antibody-functionalized biogenic magnetosome nanoparticles revealing major advantages over synthetic magnetic particles. The general principle of the M-IPCR is similar to that of a two-sided (sandwich) immunoassay. However, antibody-functionalized magnetosome conjugates were employed for the immobilization and magnetic enrichment of the signal generating detection complex enabling the establishment of a surface independent immunoassay. To this end, the M-IPCR was carried out by simultaneously tagging the antigen with the reagent for read-out, i.e., a conjugate comprising the specific antibody and DNA fragments, in the presence of the antibody-functionalized magnetosomes. To demonstrate the general functionality of the M-IPCR, the detection of recombinant Hepatitis B surface Antigen (HBsAg) in human serum was established. We observed a detection limit of 320pg/ml of HBsAg using the M-IPCR, which was about 100-fold more sensitive than the analogous Magneto-ELISA, established in parallel for comparison purposes.

An enzymatic bionanotransduction system for multianalyte biological detection

AIM

The aim of this study was to develop and optimize a system for the detection of multiple biological targets in a single sample based on enzymatic bionanotransduction.

METHOD AND RESULTS

We used biological recognition elements (antibodies, DNA sequences) linked to DNA templates with T7 promoter regions for detection of specific target molecules. In vitro transcription of DNA templates bound to target molecules produced RNA nanosignals specific for every target in the sample. An enzyme-linked oligonucleotide fluorescence assay (ELOFA) provided a correlation between nanosignal profiles and target concentrations. The system was capable of detecting and distinguishing three species of specific immunoglobulin G (IgG) molecules at a level of 0.2 ng, mixed protein and DNA targets and single sample detection of Escherichia coli O157 micro-organisms and Staphylococcal enterotoxin B (SEB).

CONCLUSIONS

This report provided proof of concept for the use of enzymatic bionanotransduction with multianalyte biological detection based on differential nanosignal hybridization along with the application of this system to pathogen/toxin detection.

SIGNIFICANCE AND IMPACT OF THE STUDY

This system has the potential to be used as a tool for detection of multiple foodborne and environmental pathogens, toxins and targets of interest in a single sample.

Protein detection using biobarcodes

Over the past 50 years the development of assays for the detection of protein analytes has been driven by continuing demands for higher levels of sensitivity and multiplexing. The result has been a progression of sandwich-type immunoassays, starting with simple radioisotopic, colorimetric, or fluorescent labeling systems to include various enzymatic or nanostructure-based signal amplification schemes, with a concomitant sensitivity increase of over 1 million fold. Multiplexing of samples and tests has been enabled by microplate and microarray platforms, respectively, or lately by various molecular barcoding systems. Two different platforms have emerged as the current front-runners by combining a nucleic acid amplification step with the standard two-sided immunoassay. In both, the captured protein analyte is replaced by a multiplicity of oligonucleotides that serve as surrogate targets. One of these platforms employs DNA or RNA polymerases for the amplification step, while detection is by fluorescence. The other is based on gold nanoparticles for both amplification as well as detection. The latter technology, now termed Biobarcode, is completely enzyme-free and offers potentially much higher multiplexing power.

Detection of ricin and other ribosome-inactivating proteins by an immuno-polymerase chain reaction assay

Ribosome-inactivating proteins (RIPs) are plant proteins with enzymatic activity, classified as type 1 (single chain) or type 2 (two chains). They are identified as rRNA N-glycosidases (EC 3.2.2.22) and cause an irreversible inhibition of protein synthesis. Among type 2 RIPs, there are potent toxins (ricin is the best known) that are considered as potential biological weapons. The development of a fast and sensitive method for the detection of biological agents is an important tool to prevent or deal with the consequences of intoxication. In this article, we describe a very sensitive immuno-polymerase chain reaction (IPCR) assay for the detection of RIPs-a type 1 RIP (dianthin) and a type 2 RIP (ricin)-that combines the specificity of immunological analysis with the exponential amplification of PCR. The limit of detection (LOD) of the technique was compared with the LODs of the conventional immunological methods enzyme-linked immunosorbent assay (ELISA) and fluorescent immunosorbent assay (FIA). The LOD of IPCR was more than 1 million times lower than that of ELISA, allowing the detection of 10 fg/ml of dianthin and ricin. The possibility to detect ricin in human serum was also investigated, and a similar sensitivity was observed (10 fg/ml). IPCR appears to be the most sensitive method for the detection of ricin and other RIPs.

A liposome-PCR assay for the ultrasensitive detection of biological toxins

We describe an ultrasensitive immunoassay for detecting biotoxins that uses liposomes with encapsulated DNA reporters, and ganglioside receptors embedded in the bilayer, as a detection reagent. After immobilization of the target biotoxin by a capture antibody and co-binding of the detection reagent, the liposomes are ruptured to release the reporters, which are quantified by real-time PCR. Assays for cholera and botulinum toxins are several orders of magnitude more sensitive than current detection methods.

Detection of norovirus capsid proteins in faecal and food samples by a real time immuno-PCR method

AIMS

To develop a sensitive real time immuno-polymerase chain reaction (rtI-PCR) method for detecting norovirus (NV) capsid protein in food samples.

METHODS AND RESULTS

The viral antigens were captured by two polyclonal antisera against recombinant Norwalk viral-like particles (rNVLPs). Biotin-conjugated antibodies, avidin and biotin-conjugated DNA reporter were used to convert the protein signals into DNA signals. The reporter DNA was then amplified by addition of primers and PCR. A real time PCR method was used in order to perform a quantitative post-PCR analysis. One hundred rNVLPs (10 fg) and a NV sample containing 660 rNVLPs equivalent particle units (66 fg) could be detected by this method.

CONCLUSION

The PCR inhibitors present in the food samples had minimal effect on antigen capture and were removed by multiple wash steps during the rtI-PCR procedure. The sensitivity of rtI-PCR was >1000-fold higher than the standard enzyme-linked immunosorbent assay and approximately 10 times higher than reverse transcription PCR in detection of NV capsid protein in stool and food samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of a rtI-PCR method to detect NV in contaminated food samples without concentration or purification of the virus.

Adaptation and performance of an immuno-PCR assay for the quantification of Aviscumine in patient plasma samples

An immuno-polymerase chain reaction (IPCR) assay is used to evaluate the kinetic behaviour of the novel anti-cancer drug Aviscumine in plasma samples taken from 41 patients during a 3-year clinical trial. The ultrasensitive IPCR assay employed the amplification of a detection-antibody linked marker-DNA and an internal competitor DNA for standardization, thus enabling the detection of the antigen in concentrations far below the detection limit of conventional enzyme-linked immuno-sorbent assay (ELISA). The quantification of Aviscumine was carried out using external calibration curves obtained from individual patient plasma samples, collected previous to the administration of Aviscumine, which were spiked with known amounts of the reference substance Aviscumine. Additional controls were measured containing standardized human serum spiked with Aviscumine to assure the continuous general reproducibility of the assay as well as to estimate differences between individual patients. Average recovery was found to be 95+/-19% and the average deviation in precision of the assay was determined to be 9+/-5%. Data for the quantification of Aviscumine were obtained from all patient samples investigated with the exception of a single patient. The collected data provided the basis for the valid routine quantification of patient samples for the calculation of the pharmacokinetic behaviour of Aviscumine in patient plasma.

Weekly 24 h infusion of aviscumine (rViscumin): a phase I study in patients with solid tumours

Aviscumine is a ribosome-inactivating protein with potent antitumour activity in vitro and in vivo and is an Escherichia coli-derived recombinant counterpart of natural mistletoe lectin-I. The current study was performed to determine the safety profile, dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of a prolonged infusion of aviscumine in cancer patients. Aviscumine was given once weekly as a 24 h central intravenous infusion in patients with advanced, refractory progressive solid malignant tumours. Fourteen fully eligible patients (11 male, 3 female) with a median age 58 yrs (range 41-77) were enrolled. They had histologically verified disease, were 18 yrs old, had an ECOG PS 2 and adequate bone marrow, liver and renal function. DLT was defined as any non-haematological grade 3-4 toxicity (Common Toxicity Criteria [CTC] version 2.0), neutrophil count <500/ microl for 7 days, febrile neutropenia or thrombocytopenia grade 4. The MTD was defined as the dose level below the dose at which 2 patients per dose level experienced a DLT during the first treatment cycle. Colorectal cancer, soft tissue sarcoma and pancreatic cancer were the most common tumour types. Dose levels of aviscumine ranged from 4 to 6 microg/kg. The median number of cycles was 2.8 (range, 2-8). Common side effects in cycle 1 were fatigue, fever, nocturia, urticaria, erythema and pruritus. DLTs occurred in 2/3 patients on the 6 microg/kg dose level and consisted of increases in ASAT grade 3, ALAT grade 3, gammaGT grade 3/4, hypokalemia grade 3 and fatigue grade 3. No DLTs were observed on dose levels 4 and 5 microg/kg. The best response (RECIST) was stable disease in 4 pts, lasting for 4-8 cycles. Pharmacokinetics indicated that potentially active plasma levels of the compound were maintained during the entire infusion. We conclude that the recommended dose for weekly 24 h infusions of Aviscumine should be 5 microg/kg.

Immuno-PCR: high sensitivity detection of proteins by nucleic acid amplification

Nucleic acid amplification techniques are used for signal generation in antibody-based immunoassays, thereby dramatically enhancing the sensitivity of conventional immunoassays. Methodological aspects, as well as applications of this novel approach, are summarized in this review, with an emphasis on immuno-polymerase chain reaction (IPCR). IPCR is based on chimeric conjugates of specific antibodies and nucleic acid molecules, the latter of which are used as markers to be amplified by PCR for signal generation. The enormous efficiency of nucleic acid amplification typically leads to a 100-10,000-fold increase in sensitivity, as compared with the analogous enzyme-amplified immunoassay. The evolution of IPCR included the development of efficient reagents, the design of assay formats and the maintenance of functionality, even within complex biological matrices. Eventually, IPCR crossed the border from being a research method to a routine laboratory technique, enabling a broad range of applications in immunological research and clinical diagnostics.

Phase I trial of intravenous aviscumine (rViscumin) in patients with solid tumors: a study of the European Organization for Research and Treatment of Cancer New Drug Development Group

BACKGROUND

Aviscumine is an Escherichia coli-derived recombinant type II ribosome-inactivating protein with potent antitumor activity in vitro and in vivo. It is the recombinant counterpart of natural mistletoe lectin-I. The current study was performed to determine the safety profile, dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of the intravenous (i.v.) administration of aviscumine in cancer patients. Translational research included the evaluation of pharmacokinetics and monitoring of plasma cytokine and anti-aviscumine antibody induction after administration of the drug.

PATIENTS AND METHODS

Aviscumine was given twice weekly as a 1 h central i.v. infusion in patients with advanced, refractory progressive, solid malignant tumors who had not been previously exposed to natural mistletoe preparations. They had histologically or cytologically verified disease, were > or =18 years old, had an Eastern Cooperative Oncology Group performance status < or =2 and adequate bone marrow, liver and renal function. DLT was defined as any non-hematological grade 3-4 toxicity (National Cancer Institute Common Toxicity Criteria version 2.0), neutrophil count <500/microl for > or =7 days, febrile neutropenia or thrombocytopenia grade 4. The MTD was defined as the dose at which >20% of patients experienced DLT during the first treatment cycle. The Continual Reassessment Method was used to determine the number of patients required per dose level.

RESULTS

Forty-one fully eligible patients (19 male, 22 female) with a median age of 56 years (range 37-74) were enrolled. Colorectal, ovarian, renal cell and breast cancer were the most common tumor types. Dose levels of aviscumine ranged from 10 to 6400 ng/kg. The median number of cycles was two (range one to eight). Common clinical toxicities in cycle 1 were fatigue, fever, nausea, vomiting and allergic reactions. Fatigue grade 3 was dose limiting in one of six patients at 4000 ng/kg and reversible grade 3 liver toxicity (elevation in alkaline phosphatase, transaminases and/or gamma-glutamyltransferase) occurred in one of 10 patients at 4800 ng/kg and in two of five patients at 6400 ng/kg. The best response (RECIST criteria) was stable disease in 11 patients, lasting for two to eight cycles. The pharmacokinetic evaluation revealed a short alpha half-life of 13 min and linear kinetics on dose levels > or =1600 ng/kg. Aviscumine stimulated the immune system with a release of cytokines such as interleukin (IL)-1beta, IL-6 and interferon-gamma, and induced immunoglobulin (Ig) G- and/or IgM-anti-aviscumine antibodies of uncertain clinical relevance.

CONCLUSIONS

The recommended dose for further clinical trials is 5600 ng/kg twice weekly. Based on the short half-life of the recombinant protein observed in this trial, the exploration of prolonged infusion schedules of aviscumine is warranted.

DDI-microFIA--A readily configurable microarray-fluorescence immunoassay based on DNA-directed immobilization of proteins

We describe a chip-based immunoassay for multiplex antigen detection, based on the self-assembly of semi-synthetic DNA-protein conjugates to generate an easily configurable protein microarray. The general principle of this microarray-fluorescence immunoassay (microFIA) is similar to that of a two-sided (sandwich) immunoassay. However, covalent single-stranded DNA-streptavidin conjugates are employed for the efficient immobilization of biotinylated capture antibodies through hybridization to complementary surface-bound DNA oligomers. In a model system, we use the DNA-directed immobilization (DDI) of antibodies to generate an antibody microarray for the parallel detection of the tumor marker human carcinoembryonic antigen (CEA), recombinant mistletoe lectin rViscumin (rVis), ceruloplasmin (CEP), and complement-1-inactivator (C1A) in human blood serum samples. Detection limits down to 400 pg mL(-1) are reached. In addition, we describe a method for the internal standardization of protein microarray analyses, based on the simultaneous measurement of constant amounts of the blood proteins CEP and C1 A, intrinsically present in human serum, to compensate for interexperimental variations usually occurring in microarray analyses. The standardization leads to a significantly higher data reliability and reproducibility in intra- and interassay measurements. We further demonstrate that the DDI-microFIA can also be carried out in a single step by tagging of the analyte simultaneously with both capture and detection antibody and subsequent immobilization of the immunocomplex formed, on the DNA microarray capture matrix. This protocol significantly reduces handling time and costs of analysis.

A real-time immuno-PCR assay for routine ultrasensitive quantification of proteins

A fast and robust assay, based on the combination of the highly sensitive immuno-PCR (IPCR), employing standardized self-assembled DNA-protein conjugates as reagents, and the well-established, reliable, and fast real-time PCR detection by means of the TaqMan principle is introduced in this work. The use of anti-species immunoglobulin reagents allows one for easy adaptation of this assay to basically any existing ELISA application. The use of an internal competitor in the real-time IPCR (rtIPCR) further increases the sensitivity and significance of this assay; 0.1-0.01 amol (500-50 fg/mL) IgG from several species (mouse, rabbit, goat, and human) were detectable using direct, indirect, and sandwich model rtIPCR assays, thereby increasing the detection limit of the analogous ELISA tests about 100- to 1000-fold. The robustness of this method was demonstrated in two typical applications by detecting 40 pg/mL of the novel anti-cancer drug rViscumin in human plasma samples as well as 100 pg/mL of a research antibody in cell culture media. In both cases, a comparable ELISA was 1000-fold less sensitive.

Combination of DNA-directed immobilization and immuno-PCR: very sensitive antigen detection by means of self-assembled DNA-protein conjugates

An assay for very sensitive antigen detection is described which takes advantage of the self- assembly capabilities of semi-synthetic conjugates of DNA and proteins. The general scheme of this assay is similar to a two-sided (sandwich) enzyme-linked immunoassay (ELISA); however, covalent single-stranded DNA-streptavidin (STV) conjugates, capable of hybridizing to complementary surface-bound DNA oligomers, are utilized for the effective immobilization of either capture antibodies or antigens, rather than the chemi- or physisorption usually applied in ELISA. Immuno-PCR (IPCR) is employed as a method for signal generation, utilizing oligomeric reagents obtained by self-assembly of STV, biotinylated DNA and antibodies. In three different model systems, detecting human IgG, rabbit IgG or carcinoembryonic antigen, this combination allowed one to increase the sensitivity of the analogous ELISA approximately 1000-fold. For example, <0.1 amol/ micro l (15 pg/ml) of rabbit IgG was detectable. The immunoassay can be carried out in a single step by tagging the analyte with both reagents for capture and read-out simultaneously, thereby significantly reducing handling time and costs of analysis. Moreover, as the spatial selectivity of target immobilization is determined by the specificity of DNA base pairing, the assay is particularly suited for miniaturized microfluidics and lab-on-a-chip devices.