ATTACK, a novel bispecific T cell-recruiting antibody with trivalent EGFR binding and monovalent CD3 binding for cancer immunotherapy

The redirection of T cell activity using bispecific antibodies is one of the most promising cancer immunotherapy approaches currently in development, but it is limited by cytokine storm-related toxicities, as well as the pharmacokinetics and tumor-penetrating capabilities of current bispecific antibody formats. Here, we have engineered the ATTACK (Asymmetric Tandem Trimerbody for T cell Activation and Cancer Killing), a novel T cell-recruiting bispecific antibody which combines three EGFR-binding single-domain antibodies (VHH; clone EgA1) with a single CD3-binding single-chain variable fragment (scFv; clone OKT3) in an intermediate molecular weight package. The two specificities are oriented in opposite directions in order to simultaneously engage cancer cells and T cell effectors, and thereby promote immunological synapse formation. EgA1 ATTACK was expressed as a homogenous, non-aggregating, soluble protein by mammalian cells and demonstrated an enhanced binding to EGFR, but not CD3, when compared to the previously characterized tandem bispecific antibody which has one EgA1 VHH and one OKT3 scFv per molecule. EgA1 ATTACK induced synapse formation and early signaling pathways downstream of TCR engagement at lower concentrations than the tandem VHH-scFv bispecific antibody. Furthermore, it demonstrated extremely potent, dose-dependent cytotoxicity when retargeting human T cells towards EGFR-expressing cells, with an efficacy over 15-fold higher than that of the tandem VHH-scFv bispecific antibody. These results suggest that the ATTACK is an ideal format for the development of the next-generation of T cell-redirecting bispecific antibodies

Tumor targeted 4-1BB agonist antibody-albumin fusions with high affinity to FcRn induce anti-tumor immunity without toxicity

17 p.-4 fig.-1 tab.-1 grph. abst.Costimulation of tumor-infiltrating T lymphocytes by anti-4-1BB monoclonal antibodies (mAbs) has shown anti-tumor activity in human trials, but can be associated with significant off-tumor toxicities involving FcγR interactions. Here, we introduce albumin-fused mouse and human bispecific antibodies with clinically favorable pharmacokinetics designed to confine 4-1BB costimulation to the tumor microenvironment. These Fc-free 4-1BB agonists consist of an EGFR-specific VHH antibody, a 4-1BB-specific scFv, and a human albumin sequence engineered for high FcRn binding connected in tandem (LiTCo-Albu). We demonstrate in vitro cognate target engagement, EGFR-specific costimulatory activity, and FcRn-driven cellular recycling similar to non-fused FcRn high-binding albumin. The mouse LiTCo-Albu exhibited a prolonged circulatory half-life and in vivo tumor inhibition, with no indication of 4-1BB mAb-associated toxicity. Furthermore, we show a greater therapeutic effect when used in combination with PD-1-blocking mAbs. These findings demonstrate the feasibility of tumor-specific LiTCo-Albu antibodies for safe and effective costimulatory strategies in cancer immunotherapy.Financial support for this work was obtained from the MCIN/AEI/10.13039/501100011033 (SAF2017-89437-P and PDC2021-121711-100 to LA-V, PID2019-104544GB-I00 to CA, and PID2020-113225GB-I00 to FJB), partially supported by the European Regional Development Fund (ERDF); the Carlos III Health Institute (ISCIII) (PI19/00132 to LS; PI20/01030 to BB), partially supported by the ERDF; the ISCIII-RICORS within the Next Generation EU program (plan de Recuperación, Transformación y Resilencia); the Spanish Association Against Cancer (AECC 19084 to LA-V); the CRIS Cancer Foundation (FCRIS-2018-0042 and FCRIS-2021-0090 to LA-V), the BBVA Foundation (Ayudas Fundación BBVA a Equipos de Investigación Científica SARS-CoV-2 years COVID-19 to LA-V); and the Fundació “La Caixa” (HR21-00761 project IL7R_LungCan to LA-V). AD, OAM, and KAH were funded by the Novo Nordisk Foundation, Grant; CEMBID (Center for Multifunctional Biomolecular Drug Design, Grant Number: NNF17OC0028070). OH was supported by an industrial PhD fellowship from the Comunidad de Madrid (IND2020/BMD-17668). AE-L was supported industrial PhD fellowship from the Carlos III Health Institute (IFI18/00045). CD-A was supported by a predoctoral fellowship from the Spanish Ministry of Science Innovation and Universities (PRE2018-083445). LR-P was supported by a predoctoral fellowship from the Immunology Chair, Universidad Francisco de Vitoria/Merck. LD-A was supported by a Rio Hortega fellowship from the Carlos III Health Institute (CM20/00004).Peer reviewe

A PD-L1/EGFR bispecific antibody combines immune checkpoint blockade and direct anti-cancer action for an enhanced anti-tumor response

Immune checkpoint blockade (ICB) with antibodies has shown durable clinical responses in a wide range of cancer types, but the overall response rate is still limited. Other effective therapeutic modalities to increase the ICB response rates are urgently needed. New bispecific antibody (bsAb) formats combining the ICB effect and a direct action on cancer cells could improve the efficacy of current immunotherapies. Here, we report the development of a PD-L1/EGFR symmetric bsAb by fusing a dual-targeting tandem trimmer body with the human IgG1 hinge and Fc regions. The bsAb was characterized in vitro and the antitumor efficacy was evaluated in humanized mice bearing xenografts of aggressive triple-negative breast cancer and lung cancer. The IgG-like hexavalent bsAb, designated IgTT-1E, was able to simultaneously bind both EGFR and PD-L1 antigens, inhibit EGF-mediated proliferation, effectively block PD-1/PD-L1 interaction, and induce strong antigen-specific antibody-dependent cellular cytotoxicity activity in vitro. Potent therapeutic efficacies of IgTT-1E in two different humanized mouse models were observed, where tumor growth control was associated with a significantly increased proportion of CD8+ T cells. These results support the development of IgTT-1E for the treatment of EGFR+ cancers.L.A-V. was supported by grants from the MCIN/AEI/10.13039/ 501100011033 (PID2020-117323RB-100 and PDC2021-121711-100), the Instituto de Salud Carlos III (DTS20/00089), the CRIS Cancer Foundation (FCRIS-2021-0090), the Spanish Association Against Cancer (PROYE19084ALVA), the Fundación ‘‘La Caixa’’ (HR21-00761 project IL7R_LungCan) and the Fundación de Investigación Biomédica 12 de Octubre Programa Investiga (2022-0082). B.B and L.S. were supported by grants PI20/01030 and PI19/00132 from the Instituto de Salud Carlos III (PI20/01030). FJB and MF-G were supported by grants PID2020- 113225GB-I00 and PRE2018-085788 funded by MCIN/AEI/10.13039/ 501100011033. L.R-P. was supported by a predoctoral fellowship from the Immunology Chair, Universidad Francisco de Vitoria/Merck. C. D-A. was supported by a predoctoral fellowship from the MCIN/AEI/ 10.13039/501100011033 (PRE2018-083445). L.D-A. was supported by a Rio Hortega fellowship from the Instituto de Salud Carlos III (CM20/ 00004). O.H. was supported by an industrial PhD fellowship from the Comunidad de Madrid (IND2020/BMD-17668). AE-L was supported industrial PhD fellowship from the Instituto de Salud Carlos III (IFI18/ 00045)Peer reviewe

Running title: Non-toxic broad anti-tumor activity of an EGFR×4-1BB bispecific trimerbod

32 p.-4 fig.Purpose: The induction of 4-1BB signaling by agonistic antibodies can drive the activation and proliferation of effector T cells and thereby enhance a T-cell–mediated antitumor response. Systemic administration of anti-4-1BB–agonistic IgGs, although effective preclinically, has not advanced in clinical development due to their severe hepatotoxicity.Experimental Design: Here, we generated a humanized EGFR-specific 4-1BB-agonistic trimerbody, which replaces the IgG Fc region with a human collagen homotrimerization domain. It was characterized by structural analysis and in vitro functional studies. We also assessed pharmacokinetics, antitumor efficacy, and toxicity in vivo.Results: In the presence of a T-cell receptor signal, the trimerbody provided potent T-cell costimulation that was strictly dependent on 4-1BB hyperclustering at the point of contact with a tumor antigen-displaying cell surface. It exhibits significant antitumor activity in vivo, without hepatotoxicity, in a wide range of human tumors including colorectal and breast cancer cell-derived xenografts, and non–small cell lung cancer patient-derived xenografts associated with increased tumor-infiltrating CD8+ T cells. The combination of the trimerbody with a PD-L1 blocker led to increased IFNγ secretion in vitro and resulted in tumor regression in humanized mice bearing aggressive triple-negative breast cancer.Conclusions: These results demonstrate the nontoxic broad antitumor activity of humanized Fc-free tumor-specific 4-1BB-agonistic trimerbodies and their synergy with checkpoint blockers, which may provide a way to elicit responses in most patients with cancer while avoiding Fc-mediated adverse reactions.This work was supported by grants from the European Union [IACT Project (602262), H2020-iNEXT (1676)]; the Spanish Ministry of Science, Innovation and Universities and the Spanish Ministry of Economy and Competitiveness (SAF2017-89437-P, CTQ2017-83810-R, RTC-2016-5118-1, RTC-2017-5944-1), partially supported by the European Regional Development Fund; the Carlos III Health Institute (PI16/00357), co-founded by the Plan Nacional de Investigación and the European Union; the CRIS Cancer Foundation (FCRIS-IFI-2018); and the Spanish Association Against Cancer (AECC, 19084). C. Domínguez-Alonso was supported by a predoctoral fellowship from the Spanish Ministry of Science, Innovation and Universities (PRE2018-083445). M. Zonca was supported by the Torres Quevedo Program from the Spanish Ministry of Economy and Competitiveness, co-founded by the European Social Fund (PTQ-16-08340).Peer reviewe

Dendritic Cell-Mediated Cross-Priming by a Bispecific Neutralizing Antibody Boosts Cytotoxic T Cell Responses and Protects Mice against SARS-CoV-2

17 p.-4 fig.Administration of neutralizing antibodies (nAbs) has proved to be effective by providing immediate protection against SARS-CoV-2. However, dual strategies combining virus neutralization and immune response stimulation to enhance specific cytotoxic T cell responses, such as dendritic cell (DC) cross-priming, represent a promising field but have not yet been explored. Here, a broadly nAb, TNT, are first generated by grafting an anti-RBD biparatopic tandem nanobody onto a trimerbody scaffold. Cryo-EM data show that the TNT structure allows simultaneous binding to all six RBD epitopes, demonstrating a high-avidity neutralizing interaction. Then, by C-terminal fusion of an anti-DNGR-1 scFv to TNT, the bispecific trimerbody TNTDNGR-1 is generated to target neutralized virions to type 1 conventional DCs (cDC1s) and promote T cell cross-priming. Therapeutic administration of TNTDNGR-1, but not TNT, protects K18-hACE2 mice from a lethal SARS-CoV-2 infection, boosting virus-specific humoral responses and CD8+ T cell responses. These results further strengthen the central role of interactions with immune cells in the virus-neutralizing antibody activity and demonstrate the therapeutic potential of the Fc-free strategy that can be used advantageously to provide both immediate and long-term protection against SARS-CoV-2 and other viral infections.SARS-CoV-2 B.1.351 and B.1.167.2 viruses used in this study were obtained through the European Virus Archive Global (EVA-GLOBAL) project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 653316. SARS-CoV-2 B.1 (MAD6 isolate) was kindly provided by José M. Honrubia and Luis Enjuanes (CNB-CSIC, Madrid, Spain). The authors thank Centro de Investigación en Sanidad Animal (CISA)-Instituto Nacional de Investigaciones Agrarias (INIA-CSIC) (Valdeolmos, Madrid, Spain) for the BSL-3 facilities. Research in LA-V laboratory was funded by the BBVA Foundation (Ayudas Fundación BBVA a Equipos de Investigación Científica SARS-CoV-2 y COVID-19); the MCIN/AEI/10.13039/501100011033 (PID2020-117323RB-I00 and PDC2021-121711-I00), partially supported by the European Regional Development Fund (ERDF); the Carlos III Health Institute (ISCIII) (DTS20/00089), partially supported by the ERDF, the Spanish Association Against Cancer (AECC 19084); the CRIS Cancer Foundation (FCRIS-IFI-2018 and FCRIS-2021-0090), the Fundación Caixa-Health Research (HR21-00761 project IL7R_LungCan), and the Comunidad de Madrid (P2022/BMD-7225 NEXT_GEN_CART_MAD-CM). Work in the DS laboratory was funded by the CNIC; the European Union's Horizon 2020 research and innovation program under grant agreement ERC-2016-Consolidator Grant 725091; MCIN/AEI/10.13039/501100011033 (PID2019-108157RB); Comunidad de Madrid (B2017/BMD-3733 Immunothercan-CM); Atresmedia (Constantes y Vitales prize); Fondo Solidario Juntos (Banco Santander); and “La Caixa” Foundation (LCF/PR/HR20/00075). The CNIC was supported by the ISCIII, the MCIN and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (CEX2020-001041-S funded by MCIN/AEI/10.13039/501100011033). Research in RD laboratory was supported by the ISCIII (PI2100989) and CIBERINFEC; the European Commission Horizon 2020 Framework Programme (grant numbers 731868 project VIRUSCAN FETPROACT-2016, and 101046084 project EPIC-CROWN-2); and the Fundación Caixa-Health Research (grant number HR18-00469 project StopEbola). Research in CNB-CSIC laboratory was funded by Fondo Supera COVID-19 (Crue Universidades-Banco Santander) grant, CIBERINFEC, and Spanish Research Council (CSIC) grant 202120E079 (to J.G.-A.), CSIC grant 2020E84 (to M.E.), MCIN/AEI/10.13039/501100011033 (PID2020-114481RB-I00 to J.G-A. and M.E.), and by the European Commission-NextGenerationEU, through CSIC's Global Health Platform (PTI Salud Global) to J.G.-A. and M.E. Work in the CIB-CSIC laboratory was supported by MCIN/AEI/10.13039/501100011033 (PID2019-104544GB-I00 and 2023AEP105 to CA, and PID2020-113225GB-I00 to F.J.B.). Cryo-EM data were collected at the Maryland Center for Advanced Molecular Analyses which was supported by MPOWER (The University of Maryland Strategic Partnership). I.H.-M. receives the support of a fellowship from la Caixa Foundation (ID 100010434, fellowship code: LCF/BQ/IN17/11620074) and from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 71367. L.R.-P. was supported by a predoctoral fellowship from the Immunology Chair, Universidad Francisco de Vitoria/Merck.Peer reviewe

A tumor-targeted trimeric 4-1BB-agonistic antibody induces potent anti-tumor immunity without systemic toxicity

The costimulation of immune cells using first-generation anti-4-1BB monoclonal antibodies (mAbs) has demonstrated anti-tumor activity in human trials. Further clinical development, however, is restricted by significant off-tumor toxicities associated with Fc gamma R interactions. Here, we have designed an Fc-free tumor-targeted 4-1BB-agonistic trimerbody, 1D8(N)/(C)EGa1, consisting of three anti-4-1BB single-chain variable fragments and three anti-EGFR single-domain antibodies positioned in an extended hexagonal conformation around the collagen XVIII homotrimerization domain. The1D8(N)/(C)EGa1 trimerbody demonstrated high-avidity binding to 4-1BB and EGFR and a potent in vitro costimulatory capacity in the presence of EGFR. The trimerbody rapidly accumulates in EGFR-positive tumors and exhibits anti-tumor activity similar to IgG-based 4-1BB-agonistic mAbs. Importantly, treatment with 1D8(N)/(C)EGa1 does not induce systemic inflammatory cytokine production or hepatotoxicity associated with IgG-based 4-1BB agonists. These results implicate Fc gamma R interactions in the 4-1BB-agonist-associated immune abnormalities, and promote the use of the non-canonical antibody presented in this work for safe and effective costimulatory strategies in cancer immunotherapy

Mutation-induced dimerization of transforming growth factor-β–induced protein may drive protein aggregation in granular corneal dystrophy

Protein aggregation in the outermost layers of the cornea, which can lead to cloudy vision and in severe cases blindness, is linked to mutations in the extracellular matrix protein transforming growth factor-β–induced protein (TGFBIp). Among the most frequent pathogenic mutations are R124H and R555W, both associated with granular corneal dystrophy (GCD) characterized by the early-onset formation of amorphous aggregates. The molecular mechanisms of protein aggregation in GCD are largely unknown. In this study, we determined the crystal structures of R124H, R555W, and the lattice corneal dystrophy-associated A546T. Although there were no changes in the monomeric TGFBIp structure of any mutant that would explain their propensity to aggregate, R124H and R555W demonstrated a new dimer interface in the crystal packing, which is not present in wildtype TGFBIp or A546T. This interface, as seen in both the R124H and R555W structures, involves residue 124 of the first TGFBIp molecule and 555 in the second. The interface is not permitted by the Arg124 and Arg555 residues of wildtype TGFBIp and may play a central role in the aggregation exhibited by R124H and R555W in vivo. Using cross-linking mass spectrometry and in-line size exclusion chromatography–small-angle X-ray scattering, we characterized a dimer formed by wildtype and mutant TGFBIps in solution. Dimerization in solution also involves interactions between the N- and C-terminal domains of two TGFBIp molecules but was not identical to the crystal packing dimerization. TGFBIp-targeted interventions that disrupt the R124H/R555W crystal packing dimer interface might offer new therapeutic opportunities to treat patients with GCD

Intramolecular trimerization, a novel strategy for making multispecific antibodies with controlled orientation of the antigen binding domains

Here, we describe a new strategy that allows the rapid and efficient engineering of mono and multispecific trivalent antibodies. By fusing single-domain antibodies from camelid heavy-chain-only immunoglobulins (VHHs) to the N-terminus of a human collagen XVIII trimerization domain (TIEXVIII) we produced monospecific trimerbodies that were efficiently secreted as soluble functional proteins by mammalian cells. The purified VHH-TIEXVIII trimerbodies were trimeric in solution and exhibited excellent antigen binding capacity. Furthermore, by connecting with two additional glycine-serine-based linkers three VHH-TIEXVIII modules on a single polypeptide chain, we present an approach for the rational design of multispecific tandem trimerbodies with defined stoichiometry and controlled orientation. Using this technology we report here the construction and characterization of a tandem VHH-based trimerbody capable of simultaneously binding to three different antigens: carcinoembryonic antigen (CEA), epidermal growth factor receptor (EGFR) and green fluorescence protein (GFP). Multispecific tandem VHH-based trimerbodies were well expressed in mammalian cells, had good biophysical properties and were capable of simultaneously binding their targeted antigens. Importantly, these antibodies were very effective in inhibiting the proliferation of human epidermoid carcinoma A431 cells. Multispecific VHH-based trimerbodies are therefore ideal candidates for future applications in various therapeutic areas.FJB was supported by a grant from the Ministerio de Economía y Competitividad (CTQ2014-56966-R). JB and BO were supported by a grant from the Ministerio de Economía y Competitividad (BIO2011-22568). AA-C and AB-T were supported by Programa Torres Quevedo from Ministerio de Economía y Competitividad, cofounded by the European Social Fund (PTQ09-01-01089 and PTQ11–04604, respectively). SLH is a recipient of the 2016 Novo Scholarship