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The September AIRR-C seminar is fast approaching! On September 28th at 7:00 PST/10:00 EST/16:00 CET, Pieter Meysman of the University of Antwerp will be discussing the applications of TCR-epitope prediction models and Felix Drost of Helmholtz Munich will be discussing the prediction of T cell receptor functionality against mutant epitopes.
Register now! The seminar will last approximately 90 minutes.
The Antibody Society is pleased to be affiliated with mAbs, a multi-disciplinary journal dedicated to advancing the art and science of antibody research and development. We hope you enjoy these summaries based on the abstracts of the most read papers published in a recent issue.
All the articles are open access; PDFs can be freely downloaded by following the links below.
In this review, Darowski et al. summarize emerging approaches that aim to further evolve CAR-T cell therapy based on combinations of so-called universal or modular CAR-(modCAR-)T cells, and their respective adaptor molecules (CAR-adaptors), which mediate the crosslinking between target and effector cells. The activity of such modCAR-T cells is entirely dependent on binding of the respective CAR-adaptor to both a tumor antigen and to the CAR-expressing T cell. Contrary to conventional CAR-T cells, where the immunological synapse is established by direct interaction of CAR and membrane-bound target, modCAR-T cells provide a highly flexible and customizable development of the CAR-T cell concept and offer an additional possibility to control T cell activity.
Using a sequence-based discovery platform, Trinklein et al. identified new anti-CD3 antibodies from humanized rats that bind to multiple epitopes and elicit varying levels of T-cell activation. In T-BsAb format, 12 different anti-CD3 arms induce equivalent levels of tumor cell lysis by primary T-cells, but potency varies by a thousand-fold. The lead CD3-targeting arm stimulates very low levels of cytokine release, but drives robust tumor antigen-specific killing in vitro and in a mouse xenograft model. This new CD3-targeting antibody underpins a next-generation T-BsAb platform in which potent cytotoxicity is uncoupled from high levels of cytokine release, which may lead to a wider therapeutic window in the clinic.
In this study by Gjetting et al., the Symplex antibody discovery platform was adapted to chicken immunoglobulin genes and combined with high-throughput humanization of antibody frameworks by “mass complementarity-determining region grafting”. Wild type chickens were immunized with an immune checkpoint inhibitor programmed cell death 1 (PD1) antigen, and a repertoire of 144 antibodies was generated. The PD1 antibody repertoire was successfully humanized, and the authors found that most humanized antibodies retained affinity largely similar to that of the parental chicken antibodies. The lead antibody Sym021 blocked PD-L1 and PD-L2 ligand binding, resulting in elevated T-cell cytokine production in vitro. Detailed epitope mapping showed that the epitope recognized by Sym021 was unique compared to the clinically approved PD1 antibodies pembrolizumab and nivolumab. Moreover, Sym021 bound human PD1 with a stronger affinity (30 pM) compared to nivolumab and pembrolizumab, while also cross-reacting with cynomolgus and mouse PD1. This enabled direct testing of Sym021 in the syngeneic mouse in vivo cancer models and evaluation of preclinical toxicology in cynomolgus monkeys. Preclinical in vivo evaluation in various murine and human tumor models demonstrated a pronounced anti-tumor effect of Sym021, supporting its current evaluation in a Phase 1 clinical trial.
Please join us at the Society’s annual meeting, Antibody Engineering & Therapeutics on December 11-15, 2017 at the Manchester Grand Hyatt, San Diego, CA!
Clinical successes of the checkpoint modulators have revived the ambition to cure cancer by manipulation of the tumor microenvironment, or by unleashing or even priming (novel) adaptive immune responses. Hence, understanding the tumor microenvironment is an increasingly vital theme in the field of antibody-based therapeutics. This theme is excitingly addressed during two sessions “Antibody-based innovations in the tumor microenvironment 1 & 2”, jointly chaired by Kerry Chester and Janine Schuurman, which will be held on Thursday December 14, 2017. The sessions’ antibody-focused complementary topics are intended to expand knowledge at the cutting edge of the tumor microenvironment field, and are anticipated to boost lively discussions and stimulate new lines of thinking.
Antibody-based innovations in the tumor microenvironment (I, morning session)
Chairwomen: Kerry Chester, Professor of Molecular Medicine, UCL Cancer Institute, University College London, United Kingdom, and Janine Schuurman, Vice President Research, Genmab, Utrecht, The Netherlands
The sessions will open with a presentation by John Anderson (UCL) who will examine current thinking on immune evasion as a hallmark of cancer and why the solid tumor microenvironment is particularly hostile to immunotherapeutic function of effector cells. He will explain that, unlike adult cancers, pediatric cancers generally arise with few mutations and tend to be insensitive to existing immune modulators. Treatment approaches designed to target cell surface antigens in combination with agents to reverse immune evasion are likely to be required for this special group of patients. New data will be presented in support of this hypothesis.
Syd Johnson (MacroGenics) will then share data on how to achieve co-stimulation of immune cells specifically within the tumor microenvironment using bispecific Dual-Affinity Re-Targeting (DART) and TRIDENT antibodies that bind both tumor-specific antigens and T-cell costimulatory molecules. Importantly, tumor binding is required to trigger costimulation. The talk will be illustrated with a case study showing how to achieve optimal tumor dependent T cell engagement by varying the relative position and valence of each antibody binding site in the molecule; manufacturability, stability and PK will also be addressed.
Natalia Arenas Ramirez (University Hospital Zurich) will then present an elegant antibody-based solution to problems associated with IL-2 immunotherapy. IL2 binding to the IL-2 receptor α (CD25) subunit leads to unwanted side effects, including stimulation of immunosuppressive Tregs. The talk will describe development of NARA1, an anti-IL-2 monoclonal antibody that acts as a high-affinity CD25 mimic, preferentially stimulating CD8+ cells while keeping the Tregs low. Potent antitumor responses are achieved.
After the Networking Break, Volker Schellenberger (Amunix) will present an interesting approach to achieving activation in the tumor environment using bispecific T-cell engagers based on the ProTIA (Protease Triggered Immune Activator) platform. ProTIA combines tumor binding, proteolytic activation and polymer targeting due to an attached XTEN. Amunix’ lead molecule, AMX-168, is expected to enter clinical development in 2018.
Next, Shautong Song (Icell Kealex Therapeutics) will showcase an innovative way to focus treatment within the tumor microenvironment via bi-specific T-cell engager-armed oncolytic vaccinia virus. The treatment has several modes of action: vaccinia virus can directly lyse tumor cells and bi-specific T-cell engagement directs T-cells to kill both tumor and by-stander cells. In addition, T-cell engagement promotes T-cell infiltration into tumors and the cytokines released upon activation create a pro-inflammatory microenvironment that inhibits tumor growth. The strategy provides a sophisticated means of reducing systemic side effects associated with bi-specific T-cell engagers.
To complete the morning session, Dane Wittrup (Massachusetts Institute of Technology) will explore how classical monoclonal anti-tumor antibodies, such as anti-HER2 or anti-CD20, synergize with immune oncology antibodies, such as anti-PD-1. This is achieved not only by delivery of tumor debris to antigen presenting cells for cross presentation, but also by creating a more inflammatory state and a localized cytokine storm in the tumor microenvironment.
Antibody-based innovations in the tumor microenvironment (II, afternoon session)
Chairwomen: Janine Schuurman, Vice President Research, Genmab, Utrecht, The Netherlands and Kerry Chester, Professor of Molecular Medicine, UCL Cancer Institute, University College London, United Kingdom
The afternoon session opens with a presentation centering on adaptive immune responses boosted by therapeutic cancer vaccines using RNA. Sebastian Kreiter (BioNTech) will focus on preclinical and clinical efforts to use personalized neoepitope vaccines in combination with immunomodulatory antibodies.
Edward Roberts (UCSF) will follow with a complementary line of thinking harnessing long term anti-tumor therapeutic effects. He will share data, including imaging data, to give us insights in the requirements for effective tumor antigen trafficking to the lymph nodes by the dendritic cells. These understandings may stimulate ideas for effective T cell priming approaches.
The TNFR super family (TNFR-SF) is a highly represented target class in the immunomodulatory targets space. Clustering is an important prerequisite for agonistic effects of antibodies against these targets. Nick Wilson (Agenus) will share emerging data on the role of antibody Fc and Fc-receptor biology to optimize the agonistic properties of antibodies against this target class.
Daratumumab, an anti-CD38 antibody that is approved for the treatment of relapsed / refractory myeloma, has multiple mechanisms of actions. Apart from rapid tumor cell reduction and direct anti-tumor effects, daratumumab significantly reduces CD38+ immune suppressive cells in the tumor microenvironment. Kate Sasser (Genmab) will focus on the immune modulatory activity of this antibody substantiated with data from in vitro evaluations and clinical studies.
Bispecific antibodies directed against both CD3and a tumor target can engage non-tumor-specific T cells, resulting in effective tumor-specific cell killing. Dirk Hose (Heidelberg University) will share data on a bispecific IgG-based molecule that targets CD3 and the B-cell maturation antigen (BCMA), which has been implicated in multiple myeloma. This presentation will cover the generation of this molecule and include early stage clinical learnings.
Anti-CD3 bispecifics can have severe toxicity profiles related to the expression profile of the tumor antigen. The last speaker of this full-day session on the tumor microenvironment will share data on the improvement of the therapeutic index of an anti-CD3 bispecific antibody also directed against a widely expressed antigen, epidermal growth factor receptor (EGFR). In this case study, Leila Boustany, (CytomX) will present the localization of the activity to the tumor microenvironment, which is accomplished by an engineering approach, i.e., a protease activatable EGFRxCD3 bispecific exploiting the protease activity present in the tumor microenvironment.
We anticipate that these complementary scientific insights focusing around antibody-based innovations in the tumor microenvironment will excite us all and inspire our forward-looking capabilities.
Interested in attending the meeting? Learn more from this PDF, which includes all session summaries written by the chairpersons.
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Post written by Whitney Shatz
T-cell recruitment for the treatment of cancer has garnered substantial interest over the past thirty years [1,2]. In this type of therapy, activated tumor-specific cytotoxic T-cell lymphocytes are directed to malignant tumor, and subsequently destroy them. Activation of this mechanism relies on T cells and tumor cells being in close proximity to one another. One popular strategy for bringing the cells together involves use of a bispecific antibody [3] where the dual-antigen specificity can enable simultaneous binding of a tumor-specific antigen along with an antigen present on a cytotoxic T-cell. In addition to having the advantage of enhanced functionality compared to a monospecific antibody, garnering dual specificity from single-agent therapy can simplify the development process, e.g., only one molecule needs to be approved. Two bispecific antibodies that take advantage of this principle have been approved: catumaxomab (Removab®) for the treatment of malignant ascites secondary to epithelial cancers and blinatumomab (Blincyto®) as second-line treatment for B cell acute lymphocytic leukemia (ALL).
Catumaxomab is a monoclonal IgG-like antibody [4]. It is termed trifunctional because one of the Fab arms binds epithelial tumor cells via the epithelial cell-adhesion molecule (EpCAM) antigen site, the other Fab arm binds cytotoxic T cells via the CD3 receptor, while the Fc acts as the third site of action, selectively engaging Fcγ receptor I-, IIa- or III on accessary cells. Thusly in this strategy, tumor cell destruction relies not only on T-cell lysis, but also on T-cell activation of accessory cells such as macrophages, dendritic cells and natural killer cells, which engage in destruction of tumor cells by various mechanisms such as perforin-mediated lysis, antibody-mediated phagocytosis and cytokine release. In 2009, catumaxomab became the first bispecific antibody to be approved, for use in Europe [4].
Blinatumomab, in contrast, is a bispecific T cell engager (BiTE) [5]. It is composed of two tandem single-chain variable fragments, each with unique specificity, fused together by a short flexible linker. One arm of this bispecific molecule binds CD3 on T cells while the other arm binds CD19, an antigen found on almost all B-lineage ALL cells and in many places throughout B cell differentiation. Bridging of the two antigens enables T-cell activation and exertion of cytotoxic activity by lysis of target B cells. Two advantages of this bispecific molecule are its small size, which results in fast systemic clearance and ensures close proximity of T cells to target cell, and its flexibility, which is thought to lead to efficient induction of T-cell activation by enabling optimal interaction with target epitopes on the two opposing cell membranes. In some cases, bifunctionality is preferred over trifunctionality because of concern that the Fc receptor interactions could potentially lead to dampening of the immune response. In 2014, blinatumomab became the first bispecific antibody approved for use in the United States. It is currently being evaluated in Phase 2 clinical trials for the treatment of other ALL-related diseases [6].
Nonetheless despite very encouraging preclinical results [7-9] and extensive clinical activities [10-13], additional successful outcomes in the clinic have not been forthcoming. Of the twenty novel bispecific antibodies that entered first-in-humans clinical studies in 2014-2015, approximately half invoke a T-cell recruiting mechanism. Despite this abundance, none of these have advanced beyond Phase 1. Thus far, toxicity and lack of significant anti-tumor response appear to be the primary barriers to advancement of these agents. Improving the selectivity of T-cell activation is being examined as a way to address toxicity issues. To increase the effectiveness of the agents, alternate dose administration strategies are being tested. For example, blinatumomab’s dosing was changed to continuous infusion instead of intravenous injection to ensure continuous activation of T cells against target cells [14]. In addition, use of T-cell recruiting bispecific antibodies as first in-line treatment or as a component of combination therapies are also being evaluated to determine whether significant gains in patient response can be achieved. If such gains can be achieved with these approaches, more T-cell activating bispecific antibodies that will successfully meet patient needs may be available in the future.
1. Staerz UD, Kanagawa O, Bevan M. Hybrid antibodies can target sites for attack by T cells. Nature 1985; 314:628–31.
2. Perez P, Hoffman RW, Shaw S, Bluestone JA, Segal DM. Specific targeting of cytotoxic T cells by anti-T3 linked to anti-target cell antibody. Nature 1985; 316:354–6.
3. Weidle UH, Kontermann RE, Brinkmann U. Tumor-antigen–binding bispecific antibodies for cancer treatment. Seminars in Oncology 2014; 41:653–60.
4. Linke R, Klein A, Seimetz D. Catumaxomab: Clinical development and future directions. mAbs 2014; 2:129–36.
5. Wolf E, Hofmeister R, Kufer P, Schlereth B, Baeuerle PA. BiTEs: bispecific antibody constructs with unique anti-tumor activity. Drug Discovery Today 2005; 10:1237–44.
6. Turner J, Schneider S. Blinatumomab: A new treatment for adults with relapsed acute lymphocytic leukemia. Clin J Oncol Nurs. 2016; 20:165–8.
7. Deo YM, Sundarapandiyan K, Keler T, Wallace PK, Graziano RF. Bispecific molecules directed to the Fc receptor for IgA (FcαRI, CD89) and tumor antigens efficiently promote cell-mediated cytotoxicity of tumor targets in whole blood. J Immunol 1998; 160:1677–86.
8. Löffler A, Kufer P, Lutterbüse R, Zettl F, Daniel PT, Schwenkenbecher JM, Riethmüller G, Dörken B, Bargou RC. A recombinant bispecific single-chain antibody, CD19 x CD3, induces rapid and high lymphoma-directed cytotoxicity by unstimulated T lymphocytes. Blood 2000; 95:2098–103.
9. Heiss MM, Ströhlein MA, Jäger M, Kimmig R, Burges A, Schoberth A, Jauch K-W, Schildberg F-W, Lindhofer H. Immunotherapy of malignant ascites with trifunctional antibodies. Int J Cancer 2005; 117:435–43.
10. Begent RH, Verhaar MJ, Chester KA, Casey JL, Green AJ, Napier MP, Hope-Stone LD, Cushen N, Keep PA, Johnson CJ, et al. Clinical evidence of efficient tumor targeting based on single-chain Fv antibody selected from a combinatorial library. Nat Med 1996; 2:979–84.
11. Burges A, Wimberger P, Kümper C, Gorbounova V. Effective relief of malignant ascites in patients with advanced ovarian cancer by a trifunctional anti-EpCAM× anti-CD3 antibody: a phase I/II study. Clin Cancer Res. 2007; 13:3899-905.
12. De Gast GC, Van Houten AA, Haagen IA, Klein S, De Weger RA, Van Dijk A, Phillips J, Clark M, Bast BJ. Clinical experience with CD3 X CD19 bispecific antibodies in patients with B cell malignancies. J Hematother. 1995;4:433-7.
13. Heiss MM, Murawa P, Koralewski P, Kutarska E, Kolesnik OO, Ivanchenko VV, Dudnichenko AS, Aleknaviciene B, Razbadauskas A, Gore M, et al. The trifunctional antibody catumaxomab for the treatment of malignant ascites due to epithelial cancer: Results of a prospective randomized phase II/III trial. Int J Cancer 2010; 127:2209–21.
14. Klinger M, Brandl C, Zugmaier G, Hijazi Y, Bargou RC, Topp MS, Gökbuget N, Neumann S, Goebeler M, Viardot A, et al. Immunopharmacologic response of patients with B-lineage acute lymphoblastic leukemia to continuous infusion of T cell–engaging CD19/CD3-bispecific BiTE antibody blinatumomab. Blood 2012; 119:6226–33.
