Potent antibody therapeutics by design

Bromohydrin pyrophosphate enhances antibody-dependent cell-mediated cytotoxicity induced by therapeutic antibodies

In human blood, 1% to 5% of lymphocytes are gammadelta T cells; they mostly express the gammadelta T-cell receptor (TCR)Vgamma9, recognize nonpeptide phosphoantigens (PAgs) produced by microbes and tumor cells, and mediate different modes of lytic activities directed against tumor target cells. Antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by cytolytic lymphoid cells is essential for the clinical activity of anticancer monoclonal antibodies (mAbs), but whether PAgs affect ADCC by gammadelta T cells is unknown. Here we report that, in association with the CD20(+)-specific mAb rituximab (RTX), the synthetic PAg bromohydrin pyrophosphate (BrHPP) increased TCRVgamma9(+) cell binding to CD20(+) lymphoma cells in vitro. This combination activated phospho-ZAP70 and phospho-ERK1/2 signaling in TCRVgamma9(+) cells and strongly enhanced their ADCC activity. We obtained similar results with BrHPP in the context of the mAbs alemtuzumab and trastuzumab. Furthermore, BrHPP enhanced RTX-mediated depletion of CD20(+) cells in vitro from peripheral blood mononuclear cells of healthy subjects and enhanced ADCC by gammadelta T cells from patients with chronic lymphocytic leukemia. In cynomolgus macaques, a regimen combining RTX, BrHPP, and IL2 activated TCRVgamma9(+) lymphocytes and enhanced B-cell depletion from blood and lymph nodes. Thus, the combination with BrHPP PAg is able to improve the efficacy of cancer immunotherapy by therapeutic mAbs.

Engineering therapeutic monoclonal antibodies

During last two decades, the chimerization and humanization of monoclonal antibodies (mAbs) have led to the approval of several for the treatment of cancer, autoimmune diseases, and transplant rejection. Additional approaches have been used to further improve their in vivo activity. These include combining them with other modalities such as chemotherapy and redesigning them for improved pharmacokinetics, effector function, and signaling activity. The latter has taken advantage of new insights emerging from an increased understanding of the cellular and molecular mechanisms that are involved in the interaction of immunoglobulin G with Fc receptors and complement as well as the negative signaling resulting from the hypercrosslinking of their target antigens. Hence, mAbs have been redesigned to include mutations in their Fc portions, thereby endowing them with enhanced or decreased effector functions and more desirable pharmacokinetic properties. Their valency has been increased to decrease their dissociation rate from cells and enhance their ability to induce apoptosis and cell cycle arrest. In this review we discuss these redesigned mAbs and current data concerning their evaluation both in vitro and in vivo.

Preclinical characterization of SGN-70, a humanized antibody directed against CD70

PURPOSE

CD70 (CD27L) is a member of the tumor necrosis factor family aberrantly expressed on a number of hematologic malignancies and some carcinomas. CD70 expression on malignant cells coupled with its highly restricted expression on normal cells makes CD70 an attractive target for monoclonal antibody (mAb)-based therapies. We developed a humanized anti-CD70 antibody, SGN-70, and herein describe the antitumor activities of this mAb.

EXPERIMENTAL DESIGN

CD70 expression on primary tumors was evaluated by immunohistochemical staining of Hodgkin lymphoma, non-Hodgkin lymphoma, multiple myeloma, and renal cell carcinoma tissue microarrays. The CD70-binding and cytotoxic activities of SGN-70 were tested in vitro using a number of cell-based assays. The in vivo antitumor properties of SGN-70 were tested in severe combined immunodeficient mice bearing disseminated lymphoma and multiple myeloma xenografts. Mechanism-of-action studies were conducted using SGN-70v, a variant mAb with equivalent target-binding activity but impaired Fcgamma receptor binding compared with SGN-70.

RESULTS

Immunohistochemical analysis identified CD70 expression on approximately 40% of multiple myeloma isolates and confirmed CD70 expression on a high percentage of Hodgkin lymphoma Reed-Sternberg cells, non-Hodgkin lymphoma, and renal cell carcinoma tumors. SGN-70 lysed CD70+ tumor cells via Fc-dependent functions, including antibody-dependent cellular cytotoxicity and phagocytosis and complement fixation. In vivo, SGN-70 treatment significantly decreased tumor burden and prolonged survival of tumor-bearing mice.

CONCLUSIONS

SGN-70 is a novel humanized IgG1 mAb undergoing clinical development for the treatment of CD70+ cancers. SGN-70 possesses Fc-dependent antibody effector functions and mediates antitumor activity in vivo.

Conditional deletion of the MHC class I-related receptor FcRn reveals the sites of IgG homeostasis in mice

The MHC class I-related receptor FcRn regulates the levels and persistence of IgG in vivo. This receptor salvages IgG from lysosomal degradation within cells, and the binding properties of an IgG for FcRn correlate with in vivo half-life. FcRn is expressed at multiple different sites throughout adult life. However, the cell types and sites at which FcRn maintains IgG homeostasis are not well defined. Toward understanding the sites of FcRn function, we have generated a mouse strain in which this Fc receptor can be conditionally deleted. In combination with mice that express Cre recombinase under the control of the Tie2 promoter (Tie2-Cre), the effect of site-specific deletion of floxed FcRn in endothelial and hematopoietic cells on IgG persistence was analyzed. The pharmacokinetics and steady-state levels of IgG in Tie2-Cre mice that are homozygous for the floxed FcRn allele reveal a complete loss of FcRn function in regulating the half-lives of wild-type IgG. The primary sites for the maintenance of endogenous IgGs in mice are therefore endothelial and hematopoietic cells.

Translational strategies for development of monoclonal antibodies from discovery to the clinic

Successful strategies for the development of monoclonal antibodies require integration of knowledge with respect to target antigen properties, antibody design criteria such as affinity, isotype selection, Fc domain engineering, PK/PD properties and antibody cross-reactivity across species from the early stages of antibody development. Biophysical measurements are one of the critical components necessary for the design of effective translational strategies for lead selection and evaluation of relevant animal species for preclinical safety and efficacy studies. Incorporation of effective translational strategies from the early stages of the antibody development process is a necessity; when considered it not only reduces development time and cost, but also fosters implementation of rational decision-making throughout all phases of antibody development.

Identification of new accessible tumor antigens in human colon cancer by ex vivo protein biotinylation and comparative mass spectrometry analysis

One of the most promising new strategies for the development of efficacious cancer therapies relies on the targeted delivery of biopharmaceutical to the tumor environment by the use of selective and specific antibodies. The identification of accessible perivascular proteins selectively overexpressed in cancer tissue may facilitate the development of antibody-based biopharmaceutical administration. This approach is potentially highly selective and specific, combining the presence of tumor biomarkers readily accessible from the blood vessels and the high rate of angiogenesis characteristic of cancer tissues. We performed ex vivo perfusions of surgically resected human colon cancer using a reactive ester derivative of biotin, thus achieving a selective covalent modification of accessible proteins in vascular structures and stroma. After extraction and purification, biotinylated proteins were digested and the resulting peptides submitted to a comparative mass spectrometry-based proteomic analysis, revealing quantitative differences between normal and cancer colon. Sixty-seven of the total 367 proteins identified were found to be preferentially expressed at the tumor site. We generated human monoclonal antibodies against 2 potential tumor targets, NGAL and GW112, and we proved their selective expression in cancer colon and not or barely in healthy tissues. This article presents the first proteomic analysis of human colorectal cancer structures readily accessible from the tumor vasculature, revealing the overexpression of novel tumor antigens which may serve as selective targets for antibody-based imaging and therapeutic biomolecular strategies.

Potent antitumor activity of the anti-CD19 auristatin antibody drug conjugate hBU12-vcMMAE against rituximab-sensitive and -resistant lymphomas

Despite major advances in the treatment of non-Hodgkin lymphoma (NHL), including the use of chemotherapeutic agents and the anti-CD20 antibody rituximab, the majority of patients eventually relapse, and salvage treatments with non-cross-resistant compounds are needed to further improve patient survival. Here, we evaluated the antitumor effects of the microtubule destabilizing agent monomethyl auristatin E (MMAE) conjugated to the humanized anti-CD19 antibody hBU12 via a protease-sensitive valine-citrulline (vc) dipeptide linker. hBU12-vcMMAE induced potent tumor cell killing against rituximab-sensitive and -resistant NHL cell lines. CD19 can form heterodimers with CD21, and high levels of CD21 were reported to interfere negatively with the activity of CD19-targeted therapeutics. However, we observed comparable internalization, intracellular trafficking, and drug release in CD21(low) and CD21(high), rituximab-sensitive and -refractory lymphomas treated with hBU12-vcMMAE. Furthermore, high rates of durable regressions in mice implanted with these tumors were observed, suggesting that both rituximab resistance and CD21 expression levels do not impact on the activity of hBU12-vcMMAE. Combined, our data suggest that hBU12-vcMMAE may represent a promising addition to the treatment options for rituximab refractory NHL and other hematologic malignancies, including acute lymphoblastic leukemia.

Therapeutic antibodies: current state and future trends--is a paradigm change coming soon?

Antibody-based therapeutics currently enjoy unprecedented success, growth in research and revenues, and recognition of their potential. It appears that the promise of the "magic bullet" has largely been realized. There are currently 22 monoclonal antibodies (mAbs) approved by the United States Food and Drug Administration (FDA) for clinical use and hundreds are in clinical trials for treatment of various diseases including cancers, immune disorders, and infections. The revenues from the top five therapeutic antibodies (Rituxan, Remicade, Herceptin, Humira, and Avastin) nearly doubled from $6.4 billion in 2004 to $11.7 billion in 2006. During the last several years major pharmaceutical companies raced to acquire antibody companies, with a recent example of MedImmune being purchased for $15.6 billion by AstraZeneca. These therapeutic and business successes reflect the major advances in antibody engineering which have resulted in the generation of safe, specific, high-affinity, and non-immunogenic antibodies during the last three decades. Currently, second and third generations of antibodies are under development, mostly to improve already existing antibody specificities. However, although the refinement of already known methodologies is certainly of great importance for potential clinical use, there are no conceptually new developments in the last decade comparable, for example, to the development of antibody libraries, phage display, domain antibodies (dAbs), and antibody humanization to name a few. A fundamental question is then whether there will be another change in the paradigm of research as happened 1-2 decades ago or the current trend of gradual improvement of already developed methodologies and therapeutic antibodies will continue. Although any prediction could prove incorrect, it appears that conceptually new methodologies are needed to overcome the fundamental problems of drug (antibody) resistance due to genetic or/and epigenetic alterations in cancer and chronic infections, as well as problems related to access to targets and complexity of biological systems. If new methodologies are not developed, it is likely that gradual saturation will occur in the pipeline of conceptually new antibody therapeutics. In this scenario we will witness an increase in combination of targets and antibodies, and further attempts to personalize targeted treatments by using appropriate biomarkers as well as to develop novel scaffolds with properties that are superior to those of the antibodies now in clinical use.

Improving antibody binding affinity and specificity for therapeutic development

Affinity maturation is an important part of the therapeutic antibody development process as in vivo activity often requires high binding affinity. Here, we describe a targeted approach for affinity improvement of therapeutic antibodies. Sets of CDR residues that are solvent accessible and relatively diverse in natural antibodies are targeted for diversification. Degenerate oligonucleotides are used to generate combinatorial phage-displayed antibody libraries with varying degree of diversity at randomized positions from which high-affinity antibodies can be selected. An advantage of using antibodies for therapy is their exquisite target specificity, which enables selective antigen binding and reduces off-target effects. However, it can be useful, and often it is necessary, to generate cross-reactive antibodies binding to not only the human antigen but also the corresponding non-human primate or rodent orthologs. Such cross-reactive antibodies can be used to validate the therapeutic targeting and examine the safety profile in preclinical animal models before committing to a costly development track. We show how affinity improvement and cross-species binding can be achieved in a one-step process.

Anti-CD22 Onconase: preparation and characterization

Antibodies can be conjugated to effector molecules to derive targeted therapeutics with properties such as cell-specific cytotoxicity. The murine anti-CD22 antibody RFB4 linked to a member of the ribonuclease A superfamily, Onconase (Onc), becomes a potential drug candidate for non-Hodgkin's lymphoma. Onc is currently in Phase III clinical trials for unresectable malignant mesothelioma but conjugation to RFB4 considerably enhances its specificity for CD22+ lymphomas. RFB4-targeted Onc is effective in preclinical models, causes little non-specific toxicities in mice, and has favorable formulation properties. Derivatization and conjugation of RFB4 and Onc have been optimized.

Chapter 4: Multitasking by exploitation of intracellular transport functions the many faces of FcRn

The MHC Class I-related receptor, FcRn, transports antibodies of the immunoglobulin G (IgG) class within and across a diverse array of different cell types. Through this transport, FcRn serves multiple roles throughout adult life that extend well beyond its earlier defined function of transcytosing IgGs from mother to offspring. These roles include the maintenance of IgG levels and the delivery of antigen in the form of immune complexes to degradative compartments within cells. Recent studies have led to significant advances in knowledge of the intracellular trafficking of FcRn and (engineered) IgGs at both the molecular and cellular levels. The engineering of FcRn-IgG (or Fc) interactions to generate antibodies of increased longevity represents an area of active interest, particularly in the light of the expanding use of antibodies in therapy. The strict pH dependence of FcRn-IgG interactions, with binding at pH 6 that becomes essentially undetectable as near neutral pH is approached, is essential for efficient transport. The requirement for retention of low affinity at near neutral pH increases the complexity of engineering antibodies for increased half-life. Conversely, engineered IgGs that have gained significant binding for FcRn at this pH can be potent inhibitors of FcRn that lower endogenous IgG levels and have multiple potential uses as therapeutics. In addition, molecular studies of FcRn-IgG interactions indicate that mice have limitations as preclinical models for FcRn function, primarily due to cross-species differences in FcRn-binding specificity.

Mass spectrometry for structural characterization of therapeutic antibodies

Antibodies, also known as immunoglobulins, have emerged as one of the most promising classes of therapeutics in the biopharmaceutical industry. The need for complete characterization of the quality attributes of these molecules requires sophisticated techniques. Mass spectrometry (MS) has become an essential analytical tool for the structural characterization of therapeutic antibodies, due to its superior resolution over other analytical techniques. It has been widely used in virtually all phases of antibody development. Structural features determined by MS include amino acid sequence, disulfide linkages, carbohydrate structure and profile, and many different post-translational, in-process, and in-storage modifications. In this review, we will discuss various MS-based techniques for the structural characterization of monoclonal antibodies. These techniques are categorized as mass determination of intact antibodies, and as middle-up, bottom-up, top-down, and middle-down structural characterizations. Each of these techniques has its advantages and disadvantages in terms of structural resolution, sequence coverage, sample consumption, and effort required for analyses. The role of MS in glycan structural characterization and profiling will also be discussed.

Therapeutic window of an EpCAM/CD3-specific BiTE antibody in mice is determined by a subpopulation of EpCAM-expressing lymphocytes that is absent in humans

MuS110 is a BiTE antibody bispecific for murine EpCAM (CD326) and murine CD3. A recent study has shown that microS110 has significant anti tumor activity at well-tolerated doses as low as 5 microg/kg in orthotopic breast and lung cancer models (Amann et al. in Cancer Res 68:143-151, 2008). Here, we have explored the safety profile of microS110 at higher doses. Escalation to 50 microg/kg microS110 caused in mice transient loss of body weight, and transient piloerection, hypomotility, hypothermia and diarrhoea. These clinical signs coincided with serum peaks of TNF-alpha, IL-6, IL-2, IFN-gamma and IL-4, and an increase of surface markers for T cell activation. Because activation of T cells in response to BiTE antibodies is typically dependent on target cells, we analyzed mouse blood for the presence of EpCAM(+) cells. Various mouse strains presented with a subpopulation of 2-3% EpCAM(+) blood cells, mostly B and T lymphocytes, which was not detected in human blood samples. In vitro experiments in which the number of EpCAM(+) cells in blood samples was either reduced or increased suggested that both T cell activation and cytokine release in response to microS110 was dependent on the number of target-expressing cells. In support for a role of EpCAM(+) lymphocytes in the observed side effects, reduction of EpCAM(+) blood cells in mice via a low-dose pre treatment with microS110 dramatically increased the tolerability of animals up to at least 500 microg/kg of the BiTE antibody. This high tolerability to microS110 occurred in the presence of non-compromised T cells. No damage to EpCAM(+) epithelial tissues was evident from histopathological examination of animals daily injected with 100 microg/kg microS110 for 28 days. In summary, these observations suggest that side effects of microS110 in mice were largely caused by an acute T cell activation that was triggered by a subpopulation of EpCAM(+) lymphocytes. Because humans have extremely low numbers of EpCAM(+) cells in blood, this toxicity of an EpCAM-specific BiTE may be specific for mice.

Practical considerations for nonclinical safety evaluation of therapeutic monoclonal antibodies

Monoclonal antibodies (mAbs) are a well established class of therapeutics as evidenced by a large number of FDA approved mAbs for the treatment of cancers and autoimmune diseases. Monoclonal antibodies that are molecularly engineered for enhanced functions and pharmacokinetic properties are routinely being considered for development by many biotechnology companies. Safety evaluation of current generation of mAbs poses new challenges due to the highly complex nature of engineering aspects and variability induced by the diverse recombinant cell systems to generate them. This review provides a basic outline for nonclinical safety evaluation of therapeutic antibodies. Important considerations for planning a preclinical program, the types of nonclinical safety studies, and a general timeline for their conduct in relation to clinical trials are described. A list of relevant regulatory documents issued by government agencies is also provided. Adoption of these principles will greatly enhance the quality and relevance of the nonclinical safety data generated and will facilitate future development of mAb therapeutics.

Production of chimeric heavy-chain antibodies

Antibody has become a major category of therapeutics. However, IgG, the primary molecular format of existing antibody drugs, has some major shortcomings such as undesirable pharmacokinetics, high dose requirement, and high production cost, partially due to its large molecular size. Much efforts have been made to address these issues, which usually led to antibodies or antibody fragments with smaller size. However, in most cases these changes also resulted in complete or partial deletion of fragment crystallizable (Fc), which is known to be crucial for a long serum half-life through binding to FcRn and antibody-mediated cell killing through binding to Fcgamma receptors and complement. Single-domain antibodies (sdAbs) derived from camelid heavy-chain antibodies (HCAbs) provide an excellent building block for constructing antibodies with moderate size yet with an intact Fc. We describe in this chapter the construction, production, and purification of chimeric HCAbs (cHCAbs), that is, fusion of camelid sdAb to human Fc. The cHCAb has a molecular size approximately half that of IgG (80 kDa vs. 150 kDa). Production is achieved through a transient expression with a human embryonic kidney (HEK) expression system, which can rapidly provide hundreds of milligrams to low-gram quantities of soluble and glycosylated recombinant antibodies for early-stage drug development.

Single-chain Fv phage display propensity exhibits strong positive correlation with overall expression levels

Background

Single chain Fvs (scFvs) are widely applied in research, diagnostics and therapeutic settings. Display and selection from combinatorial libraries is the main route to their discovery and many factors influence the success of this process. They exhibit low thermodynamic stability, resulting in low levels of premature cytosolic folding or aggregation which facilitates sec YEG-mediated translocation and phage in E. coli. However, there is little data analysing how this is related to and influenced by scFv protein expression.

Results

We characterised the relationship between overall scFv expression and display propensity for a panel of 15 anti-tetanus toxin scFvs and found a strong positive correlation (Rho = 0.88, p < 0.005) between the two parameters. Display propensity, overall expression and soluble localisation to the periplasm and extracellular fractions were clone specific characteristics which varied despite high levels of sequence homology. There was no correlation between display of scFv or its expression in non-fused (free) form with soluble scFv localisation to the periplasm or culture supernatant. This suggests that divergence in the fate of scFv-pIII and non-fused scFv after translocation to the periplasm accounts for the observed disparity. Differential degrees of periplasmic aggregation of non-fused scFv between clones may affect the partitioning of scFv in the periplasm and culture supernatant abrogating any correlation. We suggest that these factors do not apply to the scFv-pIII fusion since it remains anchored to the bacterial inner membrane as part of the innate phage packaging and budding process.

Conclusion

We conclude that in the absence of premature cytosolic aggregation or folding, the propensity of a scFv to be displayed on phage is directly related to its overall expression level and is thus indirectly influenced by factors such as codon bias, mRNA abundance or putative DNA motifs affecting expression. This suggests that scFvs capable of high overall expression and display levels may not produce high yields of non phage-fused soluble protein in either the periplasmic or extracellular fractions of E. coli. This should be considered when screening clones selected from combinatorial libraries for further study.

The nucleotide and amino acid sequences of the anti-tetanus toxin scFvs have been deposited in the EMBL data base: accession numbers-C1: AM749134, C2: AM749135, C3: AM749136, C4: AM749137, C5: AM749138, N1: AM749139, N2: AM749140, N3: AM749141, N4: AM749142, N5: AM749143 J1; AM749144, J2: AM749145, J3: AM749146, J4: AM749147, J5: AM749148.

Antibody-mediated delivery of interleukin-2 to the stroma of breast cancer strongly enhances the potency of chemotherapy

PURPOSE

There is an interest in the discovery of biopharmaceuticals, which are well tolerated and which potentiate the action of anthracyclines and taxanes in breast cancer therapy.

EXPERIMENTAL DESIGN

We have produced a recombinant fusion protein, composed of the human antibody fragment scFv(F16) fused to human interleukin-2 (F16-IL2), and tested its therapeutic performance in the MDA-MB-231 xenograft model of human breast cancer. The F16 antibody is specific to the alternatively spliced A1 domain of tenascin-C, which is virtually undetectable in normal tissues but is strongly expressed in the neovasculature and stroma of breast cancer.

RESULTS

When used as monotherapy, F16-IL2 displayed a strikingly superior therapeutic benefit compared with unconjugated recombinant IL-2. The administration of doxorubicin either before (8 days, 24 h, or 2 h) or simultaneously with the injection of F16-IL2 did not decrease the accumulation of immunocytokine in the tumor as measured by quantitative biodistribution analysis. Therapy experiments, featuring five once per week coadministrations of 20 mug F16-IL2 and doxorubicin, showed a statistically significant reduction of tumor growth rate and prolongation of survival at a 4 mg/kg doxorubicin dose but not at a 1 mg/kg dose. By contrast, combination of F16-IL2 with paclitaxel (5 and 1 mg/kg) exhibited a significant therapeutic benefit compared with paclitaxel alone at both dose levels. F16-IL2, alone or in combination with doxorubicin, was well tolerated in cynomolgus monkeys at doses equivalent to the ones now used in clinical studies.

CONCLUSIONS

F16-IL2 may represent a new useful biopharmaceutical for the treatment of breast cancer.

A general method for the selection of high-level scFv and IgG antibody expression by stably transfected mammalian cells

The isolation of mammalian cell lines capable of high-yield expression of recombinant antibodies is typically performed by screening multiple individual clones by limiting dilution techniques. A number of experimental strategies have recently been devised to identify high-expressing clones, but protocols are often difficult to implement, time consuming, costly and limited in terms of number of clones which can be screened. In this article, we describe new vectors for the expression of recombinant antibodies in IgG format and in other formats, based on the single-chain Fv module, as well as a high-throughput screening procedure, based on the direct staining of antibodies transiting the membrane of a stably transfected cell, followed by preparative sorting using a high-speed cell sorter. This procedure allows, in one step, to deposit single cells into individual wells of a 96-well microtiter plate (thus facilitating cloning) and to preferentially recover those rare cell populations which express dramatically higher levels of recombinant antibody. Using cell cultures followed by affinity purification techniques, we could confirm that the new vectors and the new screening procedure reliably yield high-expression clones and homogenous protein preparations. We expect that these techniques should find broad applicability for both academic and industrial antibody engineering research.

Complete eradication of human B-cell lymphoma xenografts using rituximab in combination with the immunocytokine L19-IL2

The antibody-mediated delivery of therapeutic agents to sites of angiogenesis is an attractive strategy for anticancer therapy, but is largely unexplored in hematologic malignancies. In the present study, we show that the extra domain B (EDB) of fibronectin, a marker of angiogenesis, is expressed in B-cell non-Hodgkin lymphoma (NHL) and that the human monoclonal anti-EDB antibody L19 can selectively localize to the lymphoma-associated subendothelial extracellular matrix. In vivo, the preferential accumulation of the antibody at the tumor site was confirmed by quantitative biodistribution analyses with radioiodinated antibody preparations. The fusion protein L19-IL2, which mediates the delivery of interleukin-2 (IL-2) to the neovasculature, displayed a superior antilymphoma activity compared with unconjugated IL-2 in localized and systemic xenograft models of NHL. When coadministered with rituximab, L19-IL2 induced complete remissions of established localized lymphomas and provided long-lasting protection from disseminated lymphoma. The combined use of rituximab and L19-IL2, which dramatically increases the infiltration of immune effector cells in lymphomas, may deserve clinical investigations, facilitated by the fact that L19-IL2 is currently being studied in phase II clinical trials in patients with solid tumors.

Generation of potent neutralizing human monoclonal antibodies against cytomegalovirus infection from immune B cells

Background

Human monoclonal antibodies (mAbs) generated as a result of the immune response are likely to be the most effective therapeutic antibodies, particularly in the case of infectious diseases against which the immune response is protective.

Human cytomegalovirus (HCMV) is an ubiquitous opportunistic virus that is the most serious pathogenic agent in transplant patients. The available therapeutic armamentarium (e.g. HCMV hyperimmune globulins or antivirals) is associated with severe side effects and the emergence of drug-resistant strains; therefore, neutralizing human mAb may be a decisive alternative in the prevention of primary and re-activated HCMV infections in these patients.

Results

The purpose of this study was to generate neutralizing mAb against HCMV from the immunological repertoire of immune donors. To this aim, we designed an efficient technology relying on two discrete and sequential steps: first, human B-lymphocytes are stimulated with TLR9-agonists and IL-2; second, after both additives are removed, the cells are infected with EBV. Using this strategy we obtained 29 clones secreting IgG neutralizing the HCMV infectivity; four among these were further characterized. All of the mAbs neutralize the infection in different combinations of HCMV strains and target cells, with a potency ~20 fold higher than that of the HCMV hyperimmune globulins, currently used in transplant recipients. Recombinant human monoclonal IgG1 suitable as a prophylactic or therapeutic tool in clinical applications has been generated.

Conclusion

The technology described has proven to be more reproducible, efficient and rapid than previously reported techniques, and can be adopted at low overall costs by any cell biology laboratory for the development of fully human mAbs for immunotherapeutic uses.

Improved tumor targeting of anti-epidermal growth factor receptor Nanobodies through albumin binding: taking advantage of modular Nanobody technology

The approximately 15-kDa variable domains of camelid heavy-chain-only antibodies (called Nanobodies) can easily be formatted as multivalent or multispecific single-chain proteins. Because of fast excretion, however, they are less suitable for therapy of cancer. In this study, we aimed for improved tumor targeting of a bivalent anti-epidermal growth factor receptor (EGFR) Nanobody (alphaEGFR-alphaEGFR) by fusion to a Nanobody unit binding to albumin (alphaAlb). Biodistributions of alphaEGFR-alphaEGFR, alphaEGFR-alphaEGFR-alphaAlb ( approximately 50 kDa), alphaTNF-alphaTNF-alphaAlb (control, binding tumor necrosis factor-alpha), and the approximately 150-kDa anti-EGFR antibody cetuximab were compared in A431 xenograft-bearing mice. The proteins were radiolabeled with (177)Lu to facilitate quantification. Tumor uptake of (177)Lu-alphaEGFR-alphaEGFR decreased from 5.0 +/- 1.4 to 1.1 +/- 0.1 %ID/g between 6 and 72 h after injection. Due to its rapid blood clearance, tumor-to-blood ratios >80 were obtained within 6 h after injection. Blood clearance became dramatically slower and tumor uptake became significantly higher by introduction of alphaAlb. Blood levels of alphaEGFR-alphaEGFR-alphaAlb were 21.2 +/- 2.5, 11.9 +/- 0.6, and 4.0 +/- 1.4 and tumor levels were 19.4 +/- 5.5, 35.2 +/- 7.5, and 28.0 +/- 6.8 %ID/g at 6, 24, and 72 h after injection, respectively. Tumor uptake was at least as high as for cetuximab (15.5 +/- 3.9, 27.1 +/- 7.9, and 25.6 +/- 6.1 %ID/g) and significantly higher than for alphaTNF-alphaTNF-alphaAlb. alphaEGFR-alphaEGFR-alphaAlb showed faster and deeper tumor penetration than cetuximab. These data show that simple fusion of alphaEGFR and alphaAlb building blocks results in a bifunctional Nanobody format, which seems more favorable for therapy as far as pharmacokinetics and tumor deposition are concerned.

Mouse-human chimeric anti-Tn IgG1 induced anti-tumor activity against Jurkat cells in vitro and in vivo

Tn-antigen (alpha-N-acetyl-galactosamine(GalNAc)-Ser/Thr) is a cancer-associated carbohydrate antigen expressed in various epithelial and hematological cancers, and although a number of anti-Tn IgG and IgM antibodies have been generated, they have not been fully validated for cancer immunotherapy. In this study, we generated a novel murine anti-Tn IgG1 monoclonal antibody, KM3413, by immunization of mucins purified from a culture supernatant of LS180: a human colon cancer cell line. The binding of KM3413 was detected against consecutive Tn-antigens (Tn3 and Tn2), but not against monovalent antigens (Tn1). The affinity (K(D)) of KM3413 was determined to be about 10(-7) M with BIAcore. Cross-reactivity against type-A blood antigen, which shares a sugar residue, alpha-linked GalNAc, with Tn-antigen, was not detected. Next, we generated mouse-human chimeric IgG1 of KM3413 (cKM3413) and evaluated its anti-tumor activities against Jurkat: a human T-lymphoid leukemia cell line. In vitro assay revealed that cKM3413 induced antibody-dependent cellular cytotoxicity (ADCC) and direct killing activity with cross-link antibody. Furthermore, treatment of cKM3413 (1 or 10 mg/kg) showed significantly better survival of Jurkat-inoculated C.B-17/lcr-scid Jcl mice compared with controls using PBS treatment (p<0.001). These results suggest that humanized antibody against clustered Tn-antigens is a promising therapeutic antibody against Tn-positive cancers.

Within peripheral blood mononuclear cells, antibody-dependent cellular cytotoxicity of rituximab-opsonized Daudi cells is promoted by NK cells and inhibited by monocytes due to shaving

Treatment of chronic lymphocytic leukemia patients with anti-CD20 mAb rituximab (RTX) leads to substantial CD20 loss on circulating malignant B cells soon after completion of the RTX infusion. This CD20 loss, which we term shaving, can compromise the therapeutic efficacy of RTX, and in vitro models reveal that shaving is mediated by effector cells which express Fc gammaRI. THP-1 monocytes and PBMC promote shaving, but PBMC also kill antibody-opsonized cells by antibody-dependent cellular cytotoxicity (ADCC), a reaction generally considered to be due to NK cells. We hypothesized that within PBMC, monocytes and NK cells would have substantially different and competing activities with respect ADCC or shaving, thereby either enhancing or inhibiting the therapeutic action of RTX. We measured ADCC and RTX removal from RTX-opsonized Daudi cells promoted by PBMC, or mediated by NK cells and monocytes. NK cells take up RTX and CD20 from RTX-opsonized B cells, and mediate ADCC. PBMC depleted of NK cells show little ADCC activity, whereas PBMC depleted of monocytes have greater ADCC than the PBMC. Pre-treatment of RTX-opsonized B cells with THP-1 cells or monocytes suppresses NK cell-mediated ADCC, and blockade of Fc gammaRI on monocytes or THP-1 cells abrogates their ability to suppress ADCC. Our results indicate NK cells are the principal cells in PBMC that kill RTX-opsonized B cells, and that monocytes can suppress ADCC by promoting shaving. These results suggest that RTX-based immunotherapy of cancer may be enhanced based on paradigms which include infusion of compatible NK cells and inhibition of monocyte shaving activity.

High accuracy 3D quantum dot tracking with multifocal plane microscopy for the study of fast intracellular dynamics in live cells

Single particle tracking in three dimensions in a live cell environment holds the promise of revealing important new biological insights. However, conventional microscopy-based imaging techniques are not well suited for fast three-dimensional (3D) tracking of single particles in cells. Previously we developed an imaging modality multifocal plane microscopy (MUM) to image fast intracellular dynamics in three dimensions in live cells. Here, we introduce an algorithm, the MUM localization algorithm (MUMLA), to determine the 3D position of a point source that is imaged using MUM. We validate MUMLA through simulated and experimental data and show that the 3D position of quantum dots can be determined over a wide spatial range. We demonstrate that MUMLA indeed provides the best possible accuracy with which the 3D position can be determined. Our analysis shows that MUM overcomes the poor depth discrimination of the conventional microscope, and thereby paves the way for high accuracy tracking of nanoparticles in a live cell environment. Here, using MUM and MUMLA we report for the first time the full 3D trajectories of QD-labeled antibody molecules undergoing endocytosis in live cells from the plasma membrane to the sorting endosome deep inside the cell.

AllergoOncology: the role of IgE-mediated allergy in cancer

Epidemiological studies have suggested inverse associations between allergic diseases and malignancies. As a proof of concept for the capability of immunoglobulin E (IgE) to destruct tumor cells, several experimental strategies have evolved to specifically target this antibody class towards relevant tumor antigens. It could be demonstrated that IgE antibodies specific to overexpressed tumor antigens have been superior to any other immunoglobulin class with respect to antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP) reactions. In an alternative approach, IgE nonspecifically attached to tumor cells proved to be a powerful adjuvant establishing tumor-specific immune memory. Active Th2 immunity could also be achieved by applying an oral immunization regimen using mimotopes, i.e. epitope mimics of tumor antigens. The induced IgE antibodies could be cross-linked by live tumor cells leading to tumoricidic mediator release. Thus, IgE antibodies may not only act in natural tumor surveillance, but could possibly also be exploited for tumor control in active and passive immunotherapy settings. Thereby, eosinophils, mast cells and macrophages can be armed with the cytophilic IgE and become potent anti-tumor effectors, able to trace viable tumor cells in the tissues. It is strongly suggested that the evolving new field AllergoOncology will give new insights into the role of IgE-mediated allergy in malignancies, possibly opening new avenues for tumor therapy.

NK cell-mediated targeting of human cancer and possibilities for new means of immunotherapy

Insights into the molecular basis for natural killer (NK) cell recognition of human cancer have been obtained in recent years. Here, we review current knowledge on the molecular specificity and function of human NK cells. Evidence for NK cell targeting of human tumors is provided and new strategies for NK cell-based immunotherapy against human cancer are discussed. Based on current knowledge, we foresee a development where more cancers may be subject to treatment with drugs or other immunomodulatory agents affecting NK cells, either directly or indirectly. We also envisage a possibility that certain forms of cancers may be subject to treatment with adoptively transferred NK cells, either alone or in combination with other therapeutic interventions.

Potent anticarcinoma activity of the humanized anti-CD70 antibody h1F6 conjugated to the tubulin inhibitor auristatin via an uncleavable linker

PURPOSE

The antitubulin agent monomethyl auristatin F (MMAF) induces potent antitumor effects when conjugated via protease cleavable linkers to antibodies targeting internalizing, tumor-specific cell surface antigens. Humanized 1F6 (h1F6) is a humanized monoclonal antibody targeting CD70, a member of the tumor necrosis factor family that is expressed on hematologic malignancies and carcinomas. Here, we tested h1F6-maleimidocaproyl (mc) MMAF conjugates, consisting of an uncleavable mc linker, for their ability to interfere with the growth of CD70-positive carcinomas.

EXPERIMENTAL DESIGN

To evaluate the optimal drug per antibody ratio, we conjugated either four or eight MMAF molecules to the cysteines that comprise the interchain disulfides of h1F6 and determined antitumor activities in vitro and in xenografted mice. The tumor types tested included glioblastoma, patient-derived renal cell carcinoma (RCC) cell isolates, and standard RCC tumor cell lines.

RESULTS

All h1F6-mcMMAF conjugates potently interfered with the growth of all carcinomas in vitro and resulted in complete responses of RCC tumors implanted orthotopically or s.c. in mice. In vitro, h1F6-mcMMAF(8) was generally more potent than h1F6-mcMMAF(4). However, h1F6-mcMMAF(4) displayed equal or better efficacy than h1F6-mcMMAF(8) when administered to tumor-bearing mice.

CONCLUSIONS

We showed that h1F6-mcMMAF conjugates inhibited the growth of human carcinomas and that increased drug loading, while improving potency in vitro, did not substantially affect the pharmacodynamic and pharmacokinetic properties in vivo. Based on these findings, h1F6-mcMMAF(4), designated SGN-75, has been identified as a potential antibody-drug conjugate for clinical development.

Comparative immunohistochemistry of L19 and F16 in non-small cell lung cancer and mesothelioma: two human antibodies investigated in clinical trials in patients with cancer

The antibody-mediated targeted delivery of therapeutics to tumor sites is an attractive avenue for combating cancer while sparing normal tissues. Indeed, five derivatives of the human monoclonal antibodies L19 and F16, specific to splice isoforms of fibronectin and tenascin-C, are currently being investigated in clinical trials in patients with malignancies. Until now, a comparative immunohistochemical analysis of these antibodies, which recognize components of the modified extracellular matrix, was missing. Here, we report that the majority of NSCLC and mesothelioma specimens are stained with both antibodies in the stroma, while non-tumoral lung and mesothelium samples rarely exhibit reactivity with either L19 or F16. In our analysis, the anti-tenascin F16 antibody was found to generally exhibit a stronger staining of desmoplastic stroma surrounding tumor. This superior performance was found to be particularly striking in the case of low-grade non-small cell lung cancer.

Antibody fucosylation differentially impacts cytotoxicity mediated by NK and PMN effector cells

Glycosylation of the antibody Fc fragment is essential for Fc receptor–mediated activity. Carbohydrate heterogeneity is known to modulate the activity of effector cells in the blood, in which fucosylation particularly affects NK cell–mediated killing. Here, we investigated how the glycosylation profile of 2F8, a human IgG1 monoclonal antibody against epidermal growth factor receptor in clinical development, impacted effector function. Various 2F8 batches differing in fucosylation, galactosylation, and sialylation of the complex-type oligosaccharides in the Fc fragment were investigated. Our results confirmed that low fucose levels enhance mononuclear cell–mediated antibody-mediated cellular cytotoxicity (ADCC). In contrast, polymorphonuclear cells were found to preferentially kill via high-fucosylated antibody. Whole blood ADCC assays, containing both types of effector cells, revealed little differences in tumor cell killing between both batches. Significantly, however, high-fucose antibody induced superior ADCC in blood from granulocyte colony-stimulating factor–primed donors containing higher numbers of activated polymorphonuclear cells. In conclusion, our data demonstrated for the first time that lack of fucose does not generally increase the ADCC activity of therapeutic antibodies and that the impact of Fc glycosylation on ADCC is critically dependent on the recruited effector cell type.

Preparation and use of therapeutic antibodies primarily of human origin

Therapeutic antibodies include polyclonal immunoglobulins isolated from regular or high-titered human plasma, sera from immunized animals, and monoclonal antibodies. This array of therapeutic antibodies is used for the prevention and treatment of many infectious diseases, antibody immunodeficiencies, autoimmune and inflammatory diseases, neurological disorders, and cancers. Polyclonal human immunoglobulins are available for intramuscular injection (IGIM), intravenous infusion (IGIV) and subcutaneous infusion (SCIG). We review these products and detail the therapeutic use of polyclonal human antibodies in the treatment of antibody immunodeficiencies, including their occasional local side effects (tenderness, sterile abscesses), minor systemic side effects (chills, muscle aches, malaise, headaches) and major side effects (aseptic meningitis, nephropathy, thrombosis).

Recombinant antibodies for cancer therapy

BACKGROUND

Recombinant antibodies have evolved into successful therapeutics with 10 approved for cancer and more in the pipeline. Four of the top ten cancer therapy drugs are recombinant antibodies.

OBJECTIVES

To survey the current state-of-the-art highlighting the reasons for this success and looking ahead to the next generation of antibody therapy.

METHODS

An analysis was carried out to identify preclinical and clinical examples and the underlying concepts and mechanisms that have shown how to design better therapies.

RESULTS/CONCLUSIONS

Greater understanding of the molecular basis of cancer has led to improved antibodies and a greater selection of targets. Fine tuning of successful antibodies through modification of glycosylation, affinity, size and other parameters are paying dividends. Fc-engineering is likely to be predominant in the near future but conjugates, fragments and fusion proteins will continue to be developed and find their place in the arsenal of antibody therapeutics.

An engineered selenocysteine defines a unique class of antibody derivatives

Selenocysteine is cotranslationally inserted into proteins by recoding the stop codon UGA from termination to selenocysteine insertion. The nucleophilic selenol group of selenocysteine endows this rare amino acid with unique chemical reactivity that allows regiospecific covalent conjugation in the presence of the other natural amino acids. Using a mammalian expression system, we generated an IgG1-derived Fc fragment with a C-terminal selenocysteine in yields comparable to conventional monoclonal antibodies and conjugated it to an electrophilic derivative of a peptidomimetic that binds with high affinity and specificity to integrin alpha(4)beta(1). Through this conjugation, both the biological and chemical components are endowed with pharmacological advantages. We demonstrate that whereas the Fc protein increases the circulatory half-life from minutes to days and mediates transcytosis through binding to the neonatal Fc receptor, the peptidomimetic introduces cross-species binding to cell surface integrin alpha(4)beta(1) and blocks its interaction with vascular cell adhesion molecule-1. Compared with conventional monoclonal antibodies, our technology benefits economically from combining a generic biological component with a variable chemical component.

mRNA display selection of a high-affinity, modification-specific phospho-IkappaBalpha-binding fibronectin

The complexity of the human proteome is greatly expanded by post-translational modifications. New tools capable of recognizing these modifications in a sequence-specific fashion provide a route to purify these modified proteins, to alter protein trafficking, and to visualize signal transduction in real time. Here, we have evolved novel, modification-specific ligands that target phosphorylated IkappaBalpha. To do this, we employed mRNA display-based in vitro selection using a 30-trillion-member protein library based on the fibronectin type III domain. The selection yielded one fibronectin molecule, 10C17C25, that binds a phospho-IkappaBalpha peptide with K d = 18 nM and is over 1000-fold specific compared to the nonphosphorylated peptide. 10C17C25 specifically recognizes endogenous phosphorylated IkappaBalpha from mammalian cell extract and stabilizes phospho-IkappaBalpha in vivo. We also incorporated 10C17C25 into a FRET indicator that detects IkappaB kinase (IKK) activity in vitro, demonstrating the utility of selecting designed adaptors for kinase activity sensors.

Developing injectable immunoglobulins to treat cognitive impairment in Alzheimer's disease

BACKGROUND

Alzheimer's disease is a devastating disorder, clinically characterized by a comprehensive cognitive decline. The novel strategy of anti-amyloid-beta immunotherapy has been suggested following encouraging results obtained in murine models of Alzheimer's disease, in non-human primates, and in small-scale clinical trials.

OBJECTIVE

To examine the choice between active or passive anti-amyloid-beta immunization and the choice of the molecule to which the immune machinery should be targeted, which are central issues in future immune therapy of Alzheimer's disease.

METHODS

Research into the new area of Alzheimer's disease immune therapy is primarily based on in vivo and in vitro studies of murine models of Alzheimer's disease. The studies are hence limited to defined genetic deficiencies.

RESULTS/CONCLUSIONS

In humans, infusion of anti-amyloid-beta antibodies is considered a safer approach than active anti-amyloid-beta vaccination. Alzheimer's-disease-protective anti-amyloid-beta monoclonal antibodies should target specific epitopes within the amyloid beta(1 42) peptide, avoiding possibly harmful binding to the ubiquitous normal amyloid precursor protein. Since Alzheimer's disease immunotherapy requires repeated infusion of antibodies over a prolonged period of time, Alzheimer's disease patients will tolerate such antibodies provided the latter are exclusively of human origin. Human monoclonal antibodies that correspond to ubiquitous anti-amyloid-beta, present in all healthy humans, might bear important protective characteristics.

New magic bullets can hit more than one target

Monoclonal antibodies have emerged as an attractive and successful class of molecules for therapeutic intervention in several areas of human disease. However, evidence is accumulating that targeting a single protein, or single epitope on a protein, is not sufficient to achieve efficacy in certain diseases. The therapeutic range of monoclonal antibodies may therefore be more limited than anticipated. How can multiple antigen targeting be achieved and in what setting can it be beneficial? Intense efforts in antibody engineering have explored different ways to reach this goal and have yielded innovative classes of molecules presenting intrinsic advantages as well as challenges at different development stages.

Local secretion of anti-CTLA-4 enhances the therapeutic efficacy of a cancer immunotherapy with reduced evidence of systemic autoimmunity

Promising anti-tumor responses have been observed in the clinic using monoclonal antibodies (mAbs) that block immune checkpoints. One concern with these therapeutic agents remains the potential induction of immune breakthrough events (IBEs) resulting from the disruption of T cell homeostasis or the breaking of tolerance to self antigens. As an approach to maintaining anti-tumor responses but decreasing the likelihood of these events, the local expression of a mAb in combination with a GM-CSF-secreting cancer immunotherapy was evaluated. Using anti-cytotoxic T lymphocyte antigen (CTLA)-4 as a model antibody to test this hypothesis, tumor cell lines were generated that expressed the full-length mAb in addition to GM-CSF. Evaluation of these cell lines in two therapeutic tumor models revealed that local, cell-mediated delivery of anti-CTLA-4 from a GM-CSF-secreting tumor cell immunotherapy activated potent anti-tumor responses and prolonged overall survival at significantly lower serum mAb levels in the host. Furthermore, lowering the systemic exposure of the host to the immune modulatory mAb correlated with reduced evidence of systemic autoimmunity. This approach has broad utility for the delivery of mAbs or proteins locally from cellular immunotherapies to minimize IBEs while retaining the potent therapeutic effects of such combination treatments.

Tumor targeting by a multivalent single-chain Fv (scFv) anti-Lewis Y antibody construct

The use of single-chain variable fragment (scFv) constructs has been investigated in cancer radioimmunotherapy (RIT) and radioimmunodetection, as these molecules permit rapid tumor penetration and clearance from the serum relative to whole IgG. Multimerization of scFv constructs has demonstrated improvements in functional affinity (i.e., avidity) and maximal tumor uptake. In this paper, we report the first biodistribution and pharmacokinetics studies of a noncovalent, direct-linked scFv (V(L)-0-V(H)) trimeric/tetrameric "multimer" of the anti-Lewis Y monoclonal antibody, hu3S193. The in vitro binding and in vivo biodistribution of the hu3S193 multimer was characterized alongside the hu3S193 F(ab')(2) following radiolabeling with the Indium-111 ((111)In) radioisotope. Immunoreactivities of the radiolabeled multimer and F(ab')(2) were 73% and 53.2%, and binding affinities (K(a)) were 1.58 x 10(7) M(1) and 4.31 x 10(6) M (1) for the multimer and F(ab')(2), respectively. Maximal tumor uptake in Le(y)-positive MCF-7 breast cancer xenografted BALB/c nude mice was 12.6 +/- 2.5 percent injected dose/per gram (%ID/g) at 6 hours postinjection for the multimer and 15.7 +/- 2.1 %ID/g at 24 hours postinjection for the F(ab')(2). However, limited in vitro stability and high renal localization of radiolabeled constructs were observed, which, despite the observed tumor targeting of the hu3S193 multimer, most likely preclude its use in RIT and imaging modalities.

Getting specific: monoclonal antibodies in multiple sclerosis

For more than a decade the only therapies that were available for multiple sclerosis (MS) were two immunomodulatory drugs-interferon beta and glatiramer acetate-and the immunosuppressant mitoxantrone. Natalizumab, a monoclonal antibody against alpha4 integrin, has been approved by the US Food and Drug Administration and the European Medicines Agency on the basis of its higher efficacy than the available treatments and its good safety profile. Monoclonal antibodies that are already licensed to treat other diseases, such as cancer and autoimmune diseases, are being tested for the treatment of MS. Additionally, novel targets are currently being investigated for MS. The therapeutic use of monoclonal antibodies was initially viewed with great scepticism owing to the high rates of sensitisation against mouse proteins, their pharmacokinetic properties, and the difficulties in their production. However, most of these problems have been overcome, and monoclonal antibodies are now among the most promising therapies for MS.

When binding is enough: nonactivating antibody formats

Most therapeutic antibodies currently used in the clinic are based on the human IgG1 format, which is a bivalent molecule that efficiently interacts with the immune system's effector functions. In clinical applications where binding to the target alone is sufficient for therapeutic efficacy; however, engagement of the immune system is not required and may even cause unwanted side-effects. Likewise, bivalent binding to the target may negatively influence the therapeutic efficacy of an antibody. Here we discuss the state of the art for antibody-based therapeutics, designed to be nonactivating (i.e. do not engage the innate immune system's effector functions), in both monovalent and bivalent formats.

Protein engineering strategies for sustained glucagon-like peptide-1 receptor-dependent control of glucose homeostasis

OBJECTIVE

We have developed a novel platform for display and delivery of bioactive peptides that links the biological properties of the peptide to the pharmacokinetic properties of an antibody. Peptides engineered in the MIMETIBODY platform have improved biochemical and biophysical properties that are quite distinct from those of Fc-fusion proteins. CNTO736 is a glucagon-like peptide 1 (GLP-1) receptor agonist engineered in our MIMETIBODY platform. It retains many activities of native GLP-1 yet has a significantly enhanced pharmacokinetic profile. Our goal was to develop a long-acting GLP-1 receptor agonist with sustained efficacy.

RESEARCH DESIGN AND METHODS

In vitro and in vivo activity of CNTO736 was evaluated using a variety of rodent cell lines and diabetic animal models.

RESULTS

Acute pharmacodynamic studies in diabetic rodents demonstrate that CNTO736 reduces fasting and postprandial glucose, decreases gastric emptying, and inhibits food intake in a GLP-1 receptor-specific manner. Reduction of food intake following CNTO736 dosing is coincident with detection of the molecule in the circumventricular organs of the brain and activation of c-fos in regions protected by the blood-brain barrier. Diabetic rodents dosed chronically with CNTO736 have lower fasting and postprandial glucose and reduced body weight.

CONCLUSIONS

Taken together, our data demonstrate that CNTO736 produces a spectrum of GLP-1 receptor-dependent actions while exhibiting significantly improved pharmacokinetics relative to the native GLP-1 peptide.