Stefan Ries

A Novel Angiopoietin-2 Selective Fully Human Antibody with Potent Anti-Tumoral and Anti-Angiogenic Efficacy and Superior Side Effect Profile Compared to Pan-Angiopoietin-1/-2 Inhibitors

There is increasing experimental evidence for an important role of Angiopoietin-2 (Ang-2) in tumor angiogenesis and progression. In addition, Ang-2 is up-regulated in many cancer types and correlated with poor prognosis. To investigate the functional role of Ang-2 inhibition in tumor development and progression, we generated novel fully human antibodies that neutralize specifically the binding of Ang-2 to its receptor Tie2. The selected antibodies LC06 and LC08 recognize both rodent and human Ang-2 with high affinity, but LC06 shows a higher selectivity for Ang-2 over Ang-1 compared to LC08 which can be considered an Ang-2/Ang-1 cross-reactive antibody. Our data demonstrate that Ang-2 blockade results in potent tumor growth inhibition and pronounced tumor necrosis in subcutaneous and orthotopic tumor models. These effects are attended with a reduction of intratumoral microvessel density and tumor vessels characterized by fewer branches and increased pericyte coverage. Furthermore, anti-Ang-2 treatment strongly inhibits the dissemination of tumor cells to the lungs. Interestingly, in contrast to the Ang-2/Ang-1 cross-reactive antibody LC08 that leads to a regression of physiological vessels in the mouse trachea, the inhibition with the selective anti-Ang-2 antibody LC06 appears to be largely restricted to tumor vasculature without obvious effects on normal vasculature. Taken together, these data provide strong evidence for the selective Ang-2 antibody LC06 as promising new therapeutic agent for the treatment of various cancers.

A novel glycoengineered bispecific antibody format for targeted inhibition of epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor type I (IGF-1R) demonstrating unique molecular properties.

Background: Bispecific antibodies are currently emerging as a promising new class of cancer therapeutics. Results: The novel one-arm single chain Fab IgG bispecific antibody (XGFR) targeting IGF-1R and EGFR demonstrated potent signaling inhibition and enhanced ADCC induction. Conclusion: XGFR has shown in vitro and in vivo anti-tumor activity in pancreatic, lung, and colorectal mouse xenograft tumor models. Significance: Rational design can help to overcome low expression yields and impaired effector functions of bispecific antibodies. In the present study, we have developed a novel one-arm single chain Fab heterodimeric bispecific IgG (OAscFab-IgG) antibody format targeting the insulin-like growth factor receptor type I (IGF-1R) and the epidermal growth factor receptor (EGFR) with one binding site for each target antigen. The bispecific antibody XGFR is based on the “knob-into-hole” technology for heavy chain heterodimerization with one heavy chain consisting of a single chain Fab to prevent wrong pairing of light chains. XGFR was produced with high expression yields and showed simultaneous binding to IGF-1R and EGFR with high affinity. Due to monovalent binding of XGFR to IGF-1R, IGF-1R internalization was strongly reduced compared with the bivalent parental antibody, leading to enhanced Fc-mediated cellular cytotoxicity. To further increase immune effector functions triggered by XGFR, the Fc portion of the bispecific antibody was glycoengineered, which resulted in strong antibody-dependent cell-mediated cytotoxicity activity. XGFR-mediated inhibition of IGF-1R and EGFR phosphorylation as well as A549 tumor cell proliferation was highly effective and was comparable with a combined treatment with EGFR (GA201) and IGF-1R (R1507) antibodies. XGFR also demonstrated potent anti-tumor efficacy in multiple mouse xenograft tumor models with a complete growth inhibition of AsPC1 human pancreatic tumors and improved survival of SCID beige mice carrying A549 human lung tumors compared with treatment with antibodies targeting either IGF-1R or EGFR. In summary, we have applied rational antibody engineering technology to develop a heterodimeric OAscFab-IgG bispecific antibody, which combines potent signaling inhibition with antibody-dependent cell-mediated cytotoxicity induction and results in superior molecular properties over two established tetravalent bispecific formats.

Targeted delivery of interferon-α to hepatitis B virus-infected cells using T-cell receptor-like antibodies.

During antiviral therapy, specific delivery of interferon‐α (IFNα) to infected cells may increase its antiviral efficacy, trigger a localized immune reaction, and reduce the side effects caused by systemic administration. Two T‐cell receptor‐like antibodies (TCR‐L) able to selectively bind hepatitis B virus (HBV)‐infected hepatocytes of chronic hepatitis B patients and recognize core (HBc18‐27) and surface (HBs183‐91) HBV epitopes associated with different human leukocyte antigen (HLA)‐A*02 alleles (A*02:01, A*02:02, A*02:07, A*02:11) were generated. Each antibody was genetically linked to two IFNα molecules to produce TCR‐L/IFNα fusion proteins. We demonstrate that the fusion proteins triggered an IFNα response preferentially on the hepatocytes presenting the correct HBV‐peptide HLA‐complex and that the mechanism of the targeted IFNα response was dependent on the specific binding of the fusion proteins to the HLA/HBV peptide complexes through the TCR‐like variable regions of the antibodies. Conclusion: TCR‐L antibodies can be used to target cytokines to HBV‐infected hepatocytes in vitro. Fusion of IFNα to TCR‐L decreased the intrinsic biological activity of IFNα but preserved the overall specificity of the protein for the cognate HBV peptide/HLA complexes. This induction of an effective IFNα response selectively in HBV‐infected cells might have a therapeutic advantage in comparison to the currently used native or pegylated IFNα. (HEPATOLOGY 2012;56:2027–2038)

Prevention of hepatitis C virus infection and spread in human liver chimeric mice by an anti‐CD81 monoclonal antibody

CD81 is a required receptor for hepatitis C virus (HCV) infection of human hepatocytes in vitro. We generated several high‐affinity anti‐human CD81 monoclonal antibodies (mAbs) that demonstrated potent, specific, and cross‐genotype inhibition of HCV entry. One of these mAbs, K04, was administered to human liver chimeric mice before or after HCV infection to determine its ability to prevent HCV infection or spread of HCV infection, respectively. All vehicle control mice established HCV infection, reaching steady‐state levels of serum HCV RNA by day 21. Pretreatment of mice with K04 prevented HCV infection in all mice (n = 5). Treatment of mice with mAb K04 every 3 days for 21 days, starting at 6 hours postinfection, resulted in effective inhibition of virus spread. In 3 mice that were sacrificed on day 24, serum HCV levels remained detectable, below the limit of quantification (LOQ), indicating that infection was established, but virus spread was blocked, by the anti‐CD81 mAb. In 5 additional mice that were followed for a longer time, virus remained detectable, below LOQ, until days 24 and 30 in 4 of 5 mice. In the fifth mouse, viral load was quantifiable, but reduced to 64‐fold below the mean viral load in vehicle control at day 24. In addition, 2 of 5 mice cleared the infection by day 30 and 1 mouse had undetectable virus load from day 6 onward. Conclusion: These results demonstrate that CD81 is required for HCV infection and virus spread in vivo, and that anti‐CD81 antibodies such as K04 may have potential as broad‐spectrum antiviral agents for prevention and treatment of HCV infection. (Hepatology 2015;61:1136–1144)

Allosteric antibody inhibition of human hepsin protease

Hepsin is a type II transmembrane serine protease that is expressed in several human tissues. Overexpression of hepsin has been found to correlate with tumour progression and metastasis, which is so far best studied for prostate cancer, where more than 90% of such tumours show this characteristic. To enable improved future patient treatment, we have developed a monoclonal humanized antibody that selectively inhibits human hepsin and does not inhibit other related proteases. We found that our antibody, hH35, potently inhibits hepsin enzymatic activity at nanomolar concentrations. Kinetic characterization revealed non-linear, slow, tight-binding inhibition. This correlates with the crystal structure we obtained for the human hepsin-hH35 antibody Fab fragment complex, which showed that the antibody binds hepsin around α3-helix, located far from the active centre. The unique allosteric mode of inhibition of hH35 is distinct from the recently described HGFA (hepatocyte growth factor activator) allosteric antibody inhibition. We further explain how a small change in the antibody design induces dramatic structural rearrangements in the hepsin antigen upon binding, leading to complete enzyme inactivation.

Target-mediated drug disposition and prolonged liver accumulation of a novel humanized anti-CD81 monoclonal antibody in cynomolgus monkeys

CD81 is an essential receptor for hepatitis C virus (HCV). K21 is a novel high affinity anti-CD81 antibody with potent broad spectrum anti-HCV activity in vitro. The pharmacokinetics (PK), pharmacodynamics and liver distribution of K21 were characterized in cynomolgus monkeys after intravenous (i.v.) administration of K21. Characteristic target-mediated drug disposition (TMDD) was shown based on the PK profile of K21 and a semi-mechanistic TMDD model was used to analyze the data. From the TMDD model, the estimated size of the total target pool at baseline (Vc • Rbase) is 16 nmol/kg and the estimated apparent Michaelis-Menten constant (KM) is 4.01 nM. A simulation using estimated TMDD parameters indicated that the number of free receptors remains below 1% for at least 3 h after an i.v. bolus of 7 mg/kg. Experimentally, the availability of free CD81 on peripheral lymphocytes was measured by immunostaining with anti-CD81 antibody JS81. After K21 administration, a dose- and time-dependent reduction in free CD81 on peripheral lymphocytes was observed. Fewer than 3% of B cells could bind JS81 3 h after a 7 mg/kg dose. High concentrations of K21 were found in liver homogenates, and the liver/serum ratio of K21 increased time-dependently and reached ~160 at 168 h post-administration. The presence of K21 bound to hepatocytes was confirmed by immunohistochemistry. The fast serum clearance of K21 and accumulation in the liver are consistent with TMDD. The TMDD-driven liver accumulation of the anti-CD81 antibody K21 supports the further investigation of K21 as a therapeutic inhibitor of HCV entry.