Abstract 2270: RG7769 (PD1-TIM3), a novel heterodimeric avidity-driven T cell specific PD-1/TIM-3 bispecific antibody lacking Fc-mediated effector functions for dual checkpoint inhibition to reactivate dysfunctional T cells

Based on the unprecedented clinical efficacy of PD-1/PD-L1 pathway checkpoint inhibitors (CPI), non-redundant immune checkpoints like TIM-3, LAG-3, TIGIT or BTLA are currently being targeted, by combinatorial approaches using monospecific or bispecific antibodies. Up-regulation of TIM-3 has been described as an adaptive CPI resistance mechanism, and internal prevalence data on archival samples of CPI-naïve and -experienced patients showed co-expression of PD-1 and TIM-3 in various tumor types, consistent with literature reports. Here, we describe RG7769 (PD1-TIM3), a novel avidity driven heterodimeric PD-1/TIM-3 1+1 bispecific CrossMabVH-VL intentionally designed as high affinity PD-1 (KD 250 pM, 37°C) and low affinity TIM-3 (KD 130 nM, 37°C) Fab-moieties to specifically target PD-1+ and PD-1+ TIM-3+ T cells through avidity gain, while bypassing PD-1- TIM3+ myeloid and NK cells. In contrast to IgG4-based PD-1 antibodies and conventional IgG1-based TIM-3 Fc-effector function competent antibodies, RG7769 harbors a PG LALA containing heterodimeric KiH IgG1 Fc-region rendering the BsAb refractory to drug shaving by FcgR-expressing macrophages in the TME, while retaining IgG-pharmacokinetics. RG7769 binds to PD-1 with higher affinity than pembrolizumab and nivolumab. X-ray crystallography demonstrated that the humanized PD-1 binding Fab recognizes a unique glycosylated epitope on PD-1, and potently blocks the PD-1/PD-L1 and PD-1/PD-L2 interactions in both biochemical and reporter cell line assays. The humanized TIM-3 binding arm was identified for maximal functional activity using mixed lymphocyte reaction (MLR) assays. Compared with bivalent TIM-3 antibodies, RG7769 shows reduced binding to TIM-3+ myeloid and NK cells, but binds preferentially to dysfunctional T cells expressing PD-1 or both PD-1 and TIM-3, like tumor infiltrating lymphocytes (TILs) in the tumor microenvironment. By virtue of its monovalency, RG7769 induced low antibody internalization on activated T cells when compared with bivalent TIM-3 antibodies, overcoming a major cellular sink for TIM-3 antibodies. In functional assays, RG7769 showed increased IFN-γ secretion by in vitro generated tumor-specific T-cells, increased ex vivo tumor-specific effector functions of T cells from PBMCs of melanoma patients, and enhanced the anti-tumor-activity of TILs from melanoma patients when compared to the monospecific parental PD-1 antibody. Finally, RG7769 showed superior efficacy in controlling s.c. MC38 tumor growth in huPD-1/huTIM-3 transgenic C57/BL6 mice compared to the parental PD-1 antibody. In summary, these preclinical data support the use of RG7769 as a monotherapy and as combination partner for the treatment of patients with solid/hematological tumors. A phase I study is currently ongoing in patients with advanced metastatic solid tumors (NCT03708328).

Citation Format: Laura Laura Codarri Deak, Stefan Seeber, Mario Perro, Patrick Weber, Laura Lauener, Standford Chen, Sonja Offner, Stefan Dengl, Friederike Hesse, Adrian Zwick, Marco Boettger, Alexander Bujotzek, Jörg Benz, Guy Georges, Georg Fertig, Valeria Lifke, Jens Fischer, Stephane Leclair, Victor Levitsky, Marta Canamero, Juha Lindner, Sara Colombetti, Stefanie Bendels, Christophe Boetsch, Matthias Fueth, Merlind Muecke, Henry Kao, Pablo Umana, Christian Klein. RG7769 (PD1-TIM3), a novel heterodimeric avidity-driven T cell specific PD-1/TIM-3 bispecific antibody lacking Fc-mediated effector functions for dual checkpoint inhibition to reactivate dysfunctional T cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2270.

Abstract 1552: A novel PD1-IL2v immunocytokine for preferential cis-activation of IL-2R signaling on PD-1 expressing T cell subsets strongly potentiates anti-tumor T cell activity of PD-1 checkpoint inhibition and IL-2R-beta-gamma agonism

High-dose IL-2 is approved for patients with metastatic melanoma and renal cell cancer, but is associated with significant toxicity. We have described tumor-targeted CEA-IL2v and FAP-IL2v immunocytokines that are based on an engineered IL2v moiety with abolished binding to IL-2Ra (CD25) to avoid undesired CD25-mediated toxicities and Treg expansion. Their antibodies bind with high affinity to either CEA or FAP, which are broadly expressed in various tumors, and mediate retention/accumulation in malignant lesions. In an effort to further maximize the potency of IL-2R activation of T cells (aka signal 3) without the side effects of wildtype IL-2, we have generated PD1-IL2v that binds to the checkpoint inhibitor PD-1 and delivers IL2v preferentially in cis to PD-1+ T cells substituting binding to CD25. This enables high affinity IL2R signaling selectively in recently primed antigen specific TILs and stem-cell like subsets. Binding/competition experiments demonstrated that PD1-IL2v is 50-fold more potent than FAP-IL2v in inducing p-STAT5 in PD-1 positive T cells, whereas it has equivalent potency on PD-1 negative T cells. Notably, although Tregs can express low constitutive levels of PD-1, PD1-IL2v shows preferential binding to Teff vs. Tregs. Furthermore, PD1-IL2v can overcome Treg suppression of Tconv effector cells to a greater extent than PD-1, FAP-IL2v or their combination. For use in syngeneic mouse models muPD1-IL2v was generated. In an orthotopic pancreatic Panc02-Luciferase model administration of muPD1-IL2v (1 mg/kg IV, qw) resulted in rapid and complete elimination of tumor cells (loss of luciferase signal) and in long term survival (> 140 days) in 7/7 treated animals with protection from tumor cell re-challenge, whereas only 1/7 animals in the muPD-1 + muFAP-IL2v combination group (10 mg/kg + 2.5 mg/kg IV, qw) and none of the animals treated with the respective monotherapies showed long term survival. IHC showed that the improved outcome with muPD1-IL2v was related to a strong intra-tumoral increase of CD3+ CD8+ T cells expressing PD-1 and GrzB. In an immuno-PD study with s.c. Panc02 tumors muPD1-IL2v strongly increased the number of IFNg+ TNFa+ multifunctional and cytotoxic GrzB+ PD-1+ T cells in the tumor accompanied with a 20-fold increase in CD8/CD4 ratio and a strong increase in the CD8+ TEM population resulting in subsequent tumor control or remission in 50% of the animals, respectively. In summary, our data demonstrate that preferential cis-targeting of IL2v to PD-1+ antigen specific T cells with PD1-IL2v results in a strong potentiation of T cell response and anti-tumor efficacy as compared to the combination of PD-1 checkpoint inhibition with FAP-IL2v. These preclinical data establish PD1-IL2v as a promising next generation IL-2 for cancer immunotherapy.

Citation Format: Christian Klein, Laura Codarri-Deak, Valeria Nicolini, Stefan Seeber, Laura Lauener, Marine Richard, Esther Bommer, Maria Karagianni, Johannes Sam, Ramona Schlenker, Marisa Mariani, Petra Petra Schwalie, Sylvia Herter, Marina Bacac, Inja Waldhauer, Anne Freimoser-Grundschober, Volker Teichgraeber, Pablo Umana. A novel PD1-IL2v immunocytokine for preferential cis-activation of IL-2R signaling on PD-1 expressing T cell subsets strongly potentiates anti-tumor T cell activity of PD-1 checkpoint inhibition and IL-2R-beta-gamma agonism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1552.

Langerin+ DCs regulate innate IL-17 production in the oral mucosa during Candida albicans-mediated infection

The opportunistic fungal pathogen Candida albicans frequently causes diseases such as oropharyngeal candidiasis (OPC) in immunocompromised individuals. Although it is well appreciated that the cytokine IL-17 is crucial for protective immunity against OPC, the cellular source and the regulation of this cytokine during infection are still a matter of debate. Here, we directly visualized IL-17 production in the tongue of experimentally infected mice, thereby demonstrating that this key cytokine is expressed by three complementary subsets of CD90+ leukocytes: RAG-dependent αβ and γδ T cells, as well as RAG-independent ILCs. To determine the regulation of IL-17 production at the onset of OPC, we investigated in detail the myeloid compartment of the tongue and found a heterogeneous and dynamic mononuclear phagocyte (MNP) network in the infected tongue that consists of Zbtb46-Langerin- macrophages, Zbtb46+Langerin+ dendritic cells (DCs) and Ly6C+ inflammatory monocytes. Of those, the Langerin+ DC population stands out by its unique capacity to co-produce the cytokines IL-1β, IL-6 and IL-23, all of which promote IL-17 induction in response to C. albicans in the oral mucosa. The critical role of Langerin+ DCs for the innate IL-17 response was confirmed by depletion of this cellular subset in vivo, which compromised IL-17 induction during OPC. In conclusion, our work revealed key regulatory factors and their cellular sources of innate IL-17-dependent antifungal immunity in the oral mucosa.