Selective high-performance liquid chromatographic purification of bispecific monoclonal antibodies

Immunoglobulin G in Platelet-Derived Wound Healing Factors

We intended to reformulate an existing platelet-derived wound healing formula to target each phase of the healing wound with the appropriate phase-specific molecules. A decreased perfusion of the skin, often associated with conditions such as thalassemia, sickle cell disease, diabetes mellitus, and chronic vascular disease, is the most common etiology of cutaneous ulcers and chronic wounds. We had previously shown that a PDWHF topically applied to a chronic nonhealing ulcer of a β-thalassemia homozygote stimulated and accelerated closure of the wound. The PDWHF was prepared from a pooled platelet concentrate of a matching blood group, consisting of a combination of platelet α-granule-derived factors. Processing of the apheresis-pooled platelets yielded various amounts of proteins (3.36 g/mL ± 0.25 (SD) (N = 10)) by the better lysis buffer method. Immunoglobulin G was found to be the most abundant α-granule-secreted protein. Equally broad quantities of the IgG (10.76 ± 12.66% (SD) (N = 10)) and IgG/albumin ratios (0.6 ± 0.4 (SD) (N = 10)) were quantified. We have developed a method using a reformulated lysis buffer followed by size exclusion chromatography and affinity chromatography to extract, identify, quantify, and purify IgG from activated platelets. IgG purification was confirmed by Western blot and flow cytometry. It was thought unlikely that the platelet IgG could be accounted for by adsorption of plasma protein, though the variable quantities could account for diversity in wound healing rates. The IgG could protect the wound even from subclinical infections and functionally advance healing. It may be useful in the management of skin ulcers in the early phase of wound healing.

Controlled conductivity at low pH in Protein L chromatography enables separation of bispecific and other antibody formats by their binding valency

The complex molecular formats of recent therapeutic antibodies, including bispecific antibodies, antibody fragments, and other fusion proteins, makes the task of purifying the desired molecules in a limited number of purification steps more and more challenging. Manufacturing these complicated biologics can be substantially improved in the affinity capture stage if the simple bind-and-elute mode is accompanied by targeted removal of the impurities, such as mis-paired antibodies and oligomers or aggregates. Here, we report a method, based on the binding valency to Protein L resin, of separating proteins during the elution step by simply controlling the conductivity at low pH. We show that the method efficiently separated targeted antibodies from mis-paired and aggregated species. Notably, the number of Protein L binding sites can be built into the molecule by design to facilitate the purification. This method may be useful for purifying various antibody formats at laboratory and manufacturing scales.

A Murine, Bispecific Monoclonal Antibody Simultaneously Recognizing β-Glucan and MP65 Determinants in Candida Species

There is a real medical need of new diagnostic tools for the early recognition of invasive Candida infections. We exploited a rather simple and rapid redox methodology to construct a bispecific monoclonal antibody (bsmAb) that combines a monoclonal antibody (mAb) directed against 1,3-β-D-glucan, a well-known, pan-fungal diagnostic biomarker, with a mAb recognizing MP65, a major immunogenic mannoprotein secreted by C.albicans and other Candida species. The bsmAb (MP65/bglu mAb) was successfully produced and purified at high yields and proved to bind and reveal simultaneously, with high sensitivity, the β-glucan and MP65 antigens in both purified and native forms. The MP65/bglu mAb is the first bispecific antibody generated against a fungal microorganism and may prove useful for the concurrent detection of different and clinically significant Candida biomarkers in patient sera.

Bispecific Antibodies: Molecules That Enable Novel Therapeutic Strategies

Bispecific antibodies are unique in the sense that they can bind simultaneously two different antigens. This property enables the development of therapeutic strategies that are not possible with conventional monoclonal antibodies. The large panel of imaginative bispecific antibody formats that has been developed reflects the strong interest for these molecules. Although in many cases the manufacturing of clinical grade material remains challenging, several bispecific antibody formats are currently in clinical trials.

Fucose removal from complex-type oligosaccharide enhances the antibody-dependent cellular cytotoxicity of single-gene-encoded bispecific antibody comprising of two single-chain antibodies linked to the antibody constant region

Bispecific antibodies (bsAbs) have the potential to extend binding selectivity, increase avidity and exert potent cytotoxicity due to the combination of dual specificities. scFv2-Fc type of single-gene-encoded bispecific antibody, composed of two different single-chain Fvs and an Fc, has been reported to be capable of binding to different antigens. The aim of this study was to determine the effect of fucose removal on effector functions of scFv2-Fc since fucose depletion from oligosaccharide of human IgG1 and scFv-Fc results in significant enhancement of ADCC. We generated novel single-gene-encoded bsAb with dual specificity against tumor associated glycoprotein (TAG)-72 and MUC1 mucin as fucose-negative scFv2-Fc from alpha-1,6-fucosyltransferase knock-out CHO cells and a highly fucosylated scFv2-Fc comparator from parental CHO cells. Expression, assembly and the antigen-binding activity of the scFv2-Fc were not influenced by removal of fucose. The fucose negative scFv2-Fc bound with higher avidity to FcgammaRIIIa and enhanced ADCC compared to the highly fucosylated scFv2-Fc. These results demonstrate that ADCC-enhancement by removal of fucose is effective in not only whole IgG1 and scFv-Fc, but also scFv2-Fc targeting two different antigens, and thus increases the potential of fucose-negative scFv2-Fcs as novel therapeutic candidates.

Optimizing expression and purification from cell culture medium of trispecific recombinant antibody derivatives

Antibody fragments offer the possibility to build multifunctional manifolds tailored to meet a large variety of needs. We optimized the production of a manifold consisting of one (bibody) or two (tribody) single-chain variable fragments coupled to the C-terminus of Fab chains. Different strong mammalian promoters were compared and the influence of expression media on production and recovery was investigated. Since the physical and chemical nature of these molecules largely depends on the nature of the antibody building blocks incorporated, a generally applicable process for the purification of recombinant antibody derivatives from serum containing mammalian cell culture medium was designed. To this end we compared protein L, hydroxyapatite, immobilized metal affinity chromatography, cation-exchange chromatography and hydrophobic charge induction chromatography.

Determination of canine beta2-microgloblin in plasma and urine by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay was developed for the determination of canine beta2-microglobulin (beta2-m) in plasma and urine. The detectable sensitivity for pure canine beta2-m was 0.05 microg/l and the analytical range was 0.1 to 50 microg/l. The mean analytical recovery when pure canine beta2-m was added to normal plasma was 101.9%. The mean analytical recovery in the urine was 102.1%. The intra-day variation coefficient was 3.1% in plasma, 4.3% in serum and 1.9% in urine. No difference was found between the concentration of beta2-m in plasma and serum (n=17). The concentration of beta2-m in the plasma of normal dogs was 1.82 +/- 0.57 mg/l (n=31). The mean excretion in 24 hr urine collected from normal dogs was 17.6 +/- 9.2 microg/l, 0.22 +/- 0.12 microg/kg of body weight or 14.2 +/- 9.4 microg/g of urine creatinine. The beta2-m creatinine index of random urine samples was 23.5 +/- 16.6 microg/g (n=26). There was a close correlation between the beta2-m creatinine index of 24 hr urine samples and that of random urine samples (r=0.872).

Single-step purification of bispecific monoclonal antibodies for immunotherapeutic use by hydrophobic interaction chromatography

A method for large scale production and single-step purification of bispecific antibodies is described. Hybrid-hybridomas were grown in hollow-fibre bioreactors with an average yield of 8 to 12 g of immunoglobulin per month. Bispecific antibodies were purified from the bioreactor supernatant by hydrophobic interaction chromatography which resolves bispecific antibodies, monospecific immunoglobulins, and culture medium supplements in one single chromatographic step. Proteins were analyzed by ELISA, SDS-PAGE, isoelectric focussing, indirect fluorescence staining, CTL-stimulation and T-cell proliferation assays. Finally, antibody preparations were checked for the presence of endotoxin and mouse DNA. Our results suggest that functional bispecific antibodies for use in therapeutic applications can be batch purified from bioreactor harvest by hydrophobic interaction chromatography in a single step. Compared to other methods such as affinity chromatography (protein A/G), ion-exchange or hydroxyapatite chromatography, our protocol offers a substantial reduction in labor time, cost, protein loss, and risk of contamination.

Bispecific monoclonal antibody anti-CD3 x anti-tenascin: an immunotherapeutic agent for human glioma

Besides surgery, the therapeutic possibilities for the treatment of human gliomas include adoptive cellular immunotherapy, radioimmunotherapy, immunotherapy mediated by chemoimmunoconjugates and, more recently, bispecific monoclonal antibodies (biMAbs). Anti-CD3 x anti-tenascin (TN) is the first reagent of a number of biMAbs under investigation for prospective use in vivo to maximize the cell-mediated cytolytic potential of glioma patients. This biMAb originated from the fusion of 2 parental hybridomas, made resistant by retrovirus-mediated infection to the different metabolic drugs, geneticin and methotrexate, respectively. The resulting hybrid hybridomas were selected on the basis of the double specificity for CD3 and TN, cloned several times and grown under continuous metabolic pressure. The different families of recombinant antibodies were then purified by high-pressure liquid chromatography on hydroxylapatite columns. Immunohistochemical studies on tumor specimens of different origin and histotype have shown that the selected biMAb presented a distribution pattern similar to that of the parental anti-TN MAb, maintaining the same staining homogeneity and intensity. Moreover, the mitogenic activity of anti-CD3 x anti-TN biMAb on peripheral blood mononuclear cells was similar to that featured by the parental anti-CD3 MAb. Furthermore, the hybrid molecule induced TNF-alpha gene expression in activated PBMC. Finally, the anti-CD3 x anti-TN featured the desired killer targeting ability, being able to induce a significantly increased cytotoxic activity against TN+ tumor cells.

Real-time kinetic analysis applied to the production of bispecific monoclonal antibodies for radioimmunodetection of cancer

An automated biosensor system designed for measuring molecular interactions in real-time and without labelling of the reactants has been used to evaluate the association/dissociation rate and affinity constants of bivalent monoclonal antibodies and a monovalent bispecific monoclonal antibody. Observed differences in affinity between parental and bispecific antibody produced were related to the association rate constants, since the dissociation rate constants were in the same range. Values were also closely related to radioimmunochemical data. These results indicate that the biosensor system, besides presenting several advantages for characterizing antigen-antibody interaction, is valuable for selecting monoclonal antibodies with properties which might be useful in the development of bispecific monoclonal antibodies.