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

Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

<p>Abstract</p> <p>Background</p> <p>β-cells are extremely rich in zinc and zinc homeostasis is regulated by zinc transporter proteins. β-cells are sensitive to cytokines, interleukin-1β (IL-1β) has been associated with β-cell dysfunction and -death in both type 1 and type 2 diabetes. This study explores the regulation of zinc transporters following cytokine exposure.</p> <p>Methods</p> <p>The effects of cytokines IL-1β, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) on zinc transporter gene expression were measured in INS-1-cells and rat pancreatic islets. Being the more sensitive transporter, we further explored ZnT8 (Slc30A8): the effect of ZnT8 over expression on cytokine induced apoptosis was investigated as well as expression of the insulin gene and two apoptosis associated genes, BAX and BCL2.</p> <p>Results</p> <p>Our results showed a dynamic response of genes responsible for β-cell zinc homeostasis to cytokines: IL-1β down regulated a number of zinc-transporters, most strikingly ZnT8 in both islets and INS-1 cells. The effect was even more pronounced when mixing the cytokines. TNF-α had little effect on zinc transporter expression. IFN-γ down regulated a number of zinc transporters. Insulin expression was down regulated by all cytokines. ZnT8 over expressing cells were more sensitive to IL-1β induced apoptosis whereas no differences were observed with IFN-γ, TNF-α, or a mixture of cytokines.</p> <p>Conclusion</p> <p>The zinc transporting system in β-cells is influenced by the exposure to cytokines. Particularly ZnT8, which has been associated with the development of diabetes, seems to be cytokine sensitive.</p

Programmable half-life and anti-tumour effects of bispecific T-cell engager-albumin fusions with tuned FcRn affinity

Abstract Fc-less bispecific T-cell engagers have reached the immuno-oncology market but necessitate continual infusion due to rapid clearance from the circulation. This work introduces a programmable serum half-life extension platform based on fusion of human albumin sequences engineered with either null (NB), wild type (WT) or high binding (HB) FcRn affinity combined with a bispecific T-cell engager. We demonstrate in a humanised FcRn/albumin double transgenic mouse model (AlbuMus) the ability to tune half-life based on the albumin sequence fused with a BiTE-like bispecific (anti-EGFR nanobody x anti-CD3 scFv) light T-cell engager (LiTE) construct [(t ½ 0.6 h (Fc-less LiTE), t ½ 19 hours (Albu-LiTE-NB), t ½ 26 hours (Albu-LiTE-WT), t ½ 37 hours (Albu-LiTE-HB)]. We show in vitro cognate target engagement, T-cell activation and discrimination in cellular cytotoxicity dependent on EGFR expression levels. Furthermore, greater growth inhibition of EGFR-positive BRAF mutated tumours was measured following a single dose of Albu-LiTE-HB construct compared to the Fc-less LiTE format and a full-length anti-EGFR monoclonal antibody in a new AlbuMus RAG1 knockout model introduced in this work. Programmable half-life extension facilitated by this albumin platform potentially offers long-lasting effects, better patient compliance and a method to tailor pharmacokinetics to maximise therapeutic efficacy and safety of immuno-oncology targeted biologics

G protein-coupled receptor 39 deficiency is associated with pancreatic islet dysfunction

G protein-coupled receptor (GPR)-39 is a seven-transmembrane receptor expressed mainly in endocrine and metabolic tissues that acts as a Zn(++) sensor signaling mainly through the G(q) and G(12/13) pathways. The expression of GPR39 is regulated by hepatocyte nuclear factor (HNF)-1α and HNF-4α, and in the present study, we addressed the importance of GPR39 for glucose homeostasis and pancreatic islets function. The expression and localization of GPR39 were characterized in the endocrine pancreas and pancreatic cell lines. Gpr39(−/−) mice were studied in vivo, especially in respect of glucose tolerance and insulin sensitivity, and in vitro in respect of islet architecture, gene expression, and insulin secretion. Gpr39 was down-regulated on differentiation of the pluripotent pancreatic cell line AR42J cells toward the exocrine phenotype but was along with Pdx-1 strongly up-regulated on differentiation toward the endocrine phenotype. Immunohistochemistry demonstrated that GRP39 is localized selectively in the insulin-storing cells of the pancreatic islets as well as in the duct cells of the exocrine pancreas. Gpr39(−/−) mice displayed normal insulin sensitivity but moderately impaired glucose tolerance both during oral and iv glucose tolerance tests, and Gpr39(−/−) mice had decreased plasma insulin response to oral glucose. Islet architecture was normal in the Gpr39 null mice, but expression of Pdx-1 and Hnf-1α was reduced. Isolated, perifused islets from Gpr39 null mice secreted less insulin in response to glucose stimulation than islets from wild-type littermates. It is concluded that GPR39 is involved in the control of endocrine pancreatic function, and it is suggested that this receptor could be a novel potential target for the treatment of diabetes