Dose–response curves of PD-1 and LAG-3 blockade in the PD-1/LAG-3 Jurkat reporter cell line.

BACKGROUND:This first-in-human clinical study explored lomvastomig, an immunoglobulin G1-based Fc-silenced bispecific antibody that simultaneously blocks the immune checkpoint receptors programmed cell death protein 1 (PD-1) and T-cell immunoglobulin domain and mucin domain-3. METHODS:Lomvastomig was characterized in cell cultures and preclinically in cancer mouse models. The phase 1, open-label, multicenter clinical study of lomvastomig included a dose-escalation part in patients with advanced and/or metastatic solid tumors and an expansion part with four tumor-specific cohorts, which enrolled checkpoint inhibitor (CPI)-experienced patients with melanoma and non-small-cell lung cancer (NSCLC) and CPI-naïve patients with SCLC and esophageal squamous cell carcinoma (ESCC). Primary and secondary objectives included safety/tolerability, maximum tolerated dose (MTD)/recommended dose for expansion (RDE), pharmacokinetics, drug receptor occupancy, and antitumor activity. RESULTS:39 and 95 patients were enrolled in the dose-escalation and expansion parts, respectively. Lomvastomig was well tolerated up to the highest tested dose of 2,100 mg every 2 weeks (Q2W). One dose-limiting toxicity was reported at 1,200 mg (grade 3 troponin T increase). No MTD was reached, and 2,100 mg Q2W was established as the RDE. Linear pharmacokinetics across the studied dose range suggested target saturation. Peripheral blood drug receptor occupancy on CD3+ and CD8+ was saturated at >90% throughout treatment for doses ≥70 mg. Objective responses were observed at 2,100 mg lomvastomig during dose-escalation (21%; n=19), and in the CPI-experienced melanoma (8%, n=38) and CPI-naïve ESCC (20%, n=15) expansion cohorts. CONCLUSIONS:Lomvastomig had a tolerable and manageable safety profile at 2,100 mg Q2W. Clinical activity was limited in CPI-experienced patients with melanoma and NSCLC, while an encouraging signal was observed in CPI-naïve patients with ESCC. TRIAL REGISTRATION NUMBER:NCT03708328 (registration date: 2018-10-09).

Tobemstomig provides TGI and eradication in several mouse tumor models by favoring the expansion of cytotoxic CD4 and CD8 TILs over Tregs. In vivo efficacy studies in CD34+ humanized NSG mice bearing subcutaneous or intramammary fat pad tumors treated for 4 weeks with the indicated treatments. A, Tumor growth curves of WSU subcutaneous tumors in humanized control mice and mice treated with the indicated therapies (n = 10 mice per treatment group, mean ± SEM). aPD-1, anti–PD-1. B, Tumor growth curves of OCI-Ly18 subcutaneous tumors in humanized control mice and mice treated with the indicated therapies (n = 14 mice per treatment group, mean ± SEM). C, Tumor growth curves of BC004 intramammary fat pad tumors in humanized control mice and mice treated with the indicated therapies (n = 14 mice per treatment group, mean ± SEM). D, Tumor growth curves of BxPC-3 subcutaneous tumors in humanized control mice and mice treated with the indicated therapies (n = 10 mice per treatment group, mean ± SEM). E, Representative contour plot depicting the effect of different treatments on CD4 and CD8 frequencies (gated on CD3+ T cells), Tregs (FOXP3+) vs. cytotoxic (granzyme B+) CD4 TILs (gated on CD4+ T cells), and proliferating (Ki67+) vs. cytotoxic (granzyme B+) CD8 TILs (gated on CD8+ T cells) isolated from BxPC-3 tumors. F–Q, Immunopharmacodynamic study depicting the effect of different treatments on CD45+ cells, CD4 and CD8 frequencies (gated on CD45+CD3+ T cells), Tregs (FOXP3+) vs. cytotoxic [granzyme B+ (GrzB+)] CD4 TILs, and proliferating (Ki67+) vs. cytotoxic (granzyme B+) CD8 TILs, expressed either as frequencies within the CD4+ or CD8+ T-cell gate, respectively (I, K, and O–Q), as frequencies within CD45+CD3+ T cells (J and L), or as intratumoral ratios (M and N), isolated from BxPC-3 tumors. The Kruskal–Wallis with Dunn post hoc test was used to compare TGI across treatment groups in the various mouse tumor models. The Mann–Whitney U test was used to compare TGI between tobemstomig and parental anti–PD-1. One-way ANOVA with the Tukey multiple comparison test was used to compare treatment effects on TIL subsets (*, P < 0.05; **, P < 0.01; ***, P < 0.001).

Abstract Checkpoint inhibitors targeting PD-1 have shown unprecedented clinical efficacy in several cancer indications and therefore have, revolutionized the standard of care. However, despite this advancement, only ~20-30% of the patients derive durable benefit from such a treatment. One of the suggested reasons for this limited success is the expression/activation of compensatory inhibitory pathways such as LAG-3 on tumor-reactive T cells. Therefore, it is envisioned that simultaneous antagonism of PD-1 and LAG-3 receptors would overcome this adaptive resistance mechanism and allow a more profound reinvigoration of tumor-reactive T cells. LAG-3 is constitutively expressed by regulatory T cells (on Tregs) and it has been reported that its blockade increases Treg suppressive function which could potentially off-sets the benefit of blocking LAG-3 on tumor-reactive CD8 T cells.We therefore developed a 1+1 PD1-LAG3 bispecific antibody, Tobemstomig, with a unique PD-1 binder recognizing a glycoepitope and more than 20 fold higher affinity than the LAG-3 binder which recognizes a novel and differentiated binding epitope (E3). This difference in affinities allows for an avidity driven selectivity gain to PD-1 and LAG-3 double positive T cells over and the following advantages over monospecific and other bispecific aPD-1/-L1 and aLAG-3 antibodies:1.improved targeting to tumor-reactive T cells rather than Tregs due to the selectivity gain and different expression patterns of PD-1 and LAG-3 on these two T cell types, 2.reduced internalization, 3.resistance to drug-shaving by macrophages due to Fc -silencing via P329G LALA,4.increased in vitro T cell effector functions even in the presence of Tregs, 5.in-vivo targeting and expansion of CD8 TILs, including stem-like T cells, and increase in T cell effector functions and6.superior in vivo tumor control/eradication compared to combination of monospecific anti-PD1 and anti-LAG3 antibodies,in several mouse models including Panc02 in syngeneic huPD-1xhuLAG3 dtg mice and BXPC3, WSU, OCI-Ly18 and BC004 in humanized mice Tobemstomig has completed dose escalation and is currently tested in a composite proof of concept Ph2 trial in several solid tumor indications. Citation Format: Laura Codarri-Deak, Patrick Aaron Weber, Valeria Nicolini, Christian Klein, Pablo Umana, Stefan Seeber, Mario Perro, Stephane Leclair. Tobemstomig, a novel bispecific checkpoint inhibitory antibody to preferentially block PD-1 and LAG-3 on CD8 TILs over Tregs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7534.

Expansion and differentiation of antigen-experienced PD-1+TCF-1+ stem-like CD8+ T cells into effector cells is critical for the success of immunotherapies based on PD-1 blockade1-4. Hashimoto et al. have shown that, in chronic infections, administration of the cytokine interleukin (IL)-2 triggers an alternative differentiation path of stem-like T cells towards a distinct population of 'better effector' CD8+ T cells similar to those generated in an acute infection5. IL-2 binding to the IL-2 receptor α-chain (CD25) was essential in triggering this alternative differentiation path and expanding better effectors with distinct transcriptional and epigenetic profiles. However, constitutive expression of CD25 on regulatory T cells and some endothelial cells also contributes to unwanted systemic effects from IL-2 therapy. Therefore, engineered IL-2 receptor β- and γ-chain (IL-2Rβγ)-biased agonists are currently being developed6-10. Here we show that IL-2Rβγ-biased agonists are unable to preferentially expand better effector T cells in cancer models and describe PD1-IL2v, a new immunocytokine that overcomes the need for CD25 binding by docking in cis to PD-1. Cis binding of PD1-IL2v to PD-1 and IL-2Rβγ on the same cell recovers the ability to differentiate stem-like CD8+ T cells into better effectors in the absence of CD25 binding in both chronic infection and cancer models and provides superior efficacy. By contrast, PD-1- or PD-L1-blocking antibodies alone, or their combination with clinically relevant doses of non-PD-1-targeted IL2v, cannot expand this unique subset of better effector T cells and instead lead to the accumulation of terminally differentiated, exhausted T cells. These findings provide the basis for the development of a new generation of PD-1 cis-targeted IL-2R agonists with enhanced therapeutic potential for the treatment of cancer and chronic infections.

Background Next-generation cancer immunotherapies are designed to broaden the therapeutic repertoire by targeting new immune checkpoints including lymphocyte-activation gene 3 (LAG-3) and T cell immunoglobulin and mucin-domain containing-3 (TIM-3). Yet, the molecular and cellular mechanisms by which either receptor functions to mediate its inhibitory effects are still poorly understood. Similarly, little is known on the differential effects of dual, compared with single, checkpoint inhibition.Methods We here performed in-depth characterization, including multicolor flow cytometry, single cell RNA sequencing and multiplex supernatant analysis, using tumor single cell suspensions from patients with cancer treated ex vivo with novel bispecific antibodies targeting programmed cell death protein 1 (PD-1) and TIM-3 (PD1-TIM3), PD-1 and LAG-3 (PD1-LAG3), or with anti-PD-1.Results We identified patient samples which were responsive to PD1-TIM3, PD1-LAG3 or anti-PD-1 using an in vitro approach, validated by the analysis of 659 soluble proteins and enrichment for an anti-PD-1 responder signature. We found increased abundance of an activated (HLA-DR+CD25+GranzymeB+) CD8+ T cell subset and of proliferating CD8+ T cells, in response to bispecific antibody or anti-PD-1 treatment. Bispecific antibodies, but not anti-PD-1, significantly increased the abundance of a proliferating natural killer cell subset, which exhibited enrichment for a tissue-residency signature. Key phenotypic and transcriptional changes occurred in a PD-1+CXCL13+CD4+ T cell subset, in response to all treatments, including increased interleukin-17 secretion and signaling toward plasma cells. Interestingly, LAG-3 protein upregulation was detected as a unique pharmacodynamic effect mediated by PD1-LAG3, but not by PD1-TIM3 or anti-PD-1.Conclusions Our in vitro system reliably assessed responses to bispecific antibodies co-targeting PD-1 together with LAG-3 or TIM-3 using patients’ tumor infiltrating immune cells and revealed transcriptional and phenotypic imprinting by bispecific antibody formats currently tested in early clinical trials.

Expansion of antigen-specific effector CD8 T cells is central to the control of chronic viral infections and cancer. In particular, differentiation of antigen-experienced, PD-1+TCF-1+ stem -like CD8 T cells, termed here “resource T cells”, into effector cells is critical for the success of immunotherapies based on immune checkpoint PD-1 signaling blockade1-4. In the accompanying article, Hashimoto et al. show that in chronic infections, administration of the cytokine interleukin- 2 (IL-2) triggers an alternative differentiation path from resource T cells leading to the expansion of a distinct population of effector CD8 T cells, termed “better effectors”, which are similar to effector cells generated in an acute infection. IL-2 binding to the non-signaling component of its receptor, IL-2Rα-chain, also known as CD25, was essential to trigger this alternative differentiation path and to expand better effectors with distinct transcriptional and epigenetic profiles. However, as IL-2 binding to CD25 constitutively expressed on immunosuppressive regulatory T cells and on some endothelial cells contributes to unwanted systemic effects of IL-2 therapy that have hampered its broad clinical application, a new generation of engineered IL-2Rβγ-biased agonists with reduced/abolished CD25 binding is currently being developed5-9. Here we show that IL-2Rβγ-biased agonists devoid of CD25 binding are unable to preferentially expand better effectors in cancer models, and describe a novel antibody-cytokine fusion protein, PD1-IL2v, that overcomes the need for CD25 binding by using PD-1 binding in cis in order to generate this distinct effector cell population. PD1-IL2v comprises an engineered IL-2 variant devoid of CD25 binding, fused to a high affinity PD-1 blocking antibody. In cis binding of PD1-IL2v to PD-1 and IL-2Rβγ on the same cell surface recovers the ability to differentiate resource CD8 T cells into better effectors in the absence of CD25 binding in both chronic infection and cancer models, while providing superior treatment efficacy. In contrast, PD-1/-L1 blocking antibodies alone, or their combination with clinically relevant doses of IL-2-based molecules with abolished CD25 binding and not targeted to PD-1, could not expand this unique subset of better effector T cells, and rather led to the accumulation of terminally-differentiated, exhausted T cells. These findings provide the basis for the development of a new generation of IL-2R agonists with enhanced therapeutic potential for the treatment of cancer and chronic infections.

Receptor occupancy (RO) assessment by flow cytometry is an important pharmacodynamic (PD) biomarker in the clinical development of large molecules such as monoclonal therapeutic antibodies (mAbs). The total-drug-bound RO assay format directly assesses mAb binding to cell surface targets using anti-drug detection antibodies. Here, we generated a flow cytometry detection antibody specifically binding to mAbs of the IgG1 P329GLALA backbone. Using this reagent, we developed a total-drug-bound RO assay format for RG7769, a bi-specific P329GLALA containing mAb targeting PD-1 and TIM3 on T cells. In its fit-for-purpose validated version, this RO assay has been used in the Phase-I dose escalation study of RG7769, informing on peripheral T cell RO and RG7769 antibody binding capacity (ABC). We assessed RG7769 RO in checkpoint-inhibitor (CPI) naïve patients and anti-PD-1 CPI experienced patients using our novel assay. Here, we show that in both groups, complete T cell RO can be achieved (~100%). However, we found that the maximum number of T cell binding sites for RG7769 pre-dosing was roughly twofold lower in patients recently having undergone anti-PD-1 treatment. We show that this is due to steric hindrance exerted by competing mAbs masking the available drug binding sites. Our findings highlight the importance of quantitative mAb assessment in addition to relative RO especially in the context of patients who have previously received anti-PD-1 treatment.

Abstract 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.

In this article, Artopoeus' translation of the Byzantine novel by Eustathios Makrembolites is read as a meta-poetic contribution to the developing genre of the novel in the late 16th century. Artopoeus uses the erudite source which is relying heavily on ancient models, and inserts it into his contemporary discourse - his Ismenius offers reflections on how to read and what to gain from reading a novel, presented in lengthy paratextual reading instructions (one of them written by Fischart) and with special emphasis on the ekphrastic value of the story.

In this article, Artopoeus’ translation of the Byzantine novel by Eustathios Makrembolites is read as a meta-poetic contribution to the developing genre of the novel in the late 16th century. Artopoeus uses the erudite source which is relying heavily on ancient models, and inserts it into his contemporary discourse – his Ismenius offers reflections on how to read and what to gain from reading a novel, presented in lengthy paratextual reading instructions (one of them written by Fischart) and with special emphasis on the ekphrastic value of the story.

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.

PURPOSE:The Göttingen minipig is a relevant non-rodent species for regulatory toxicological studies. Yet, its use with therapeutic antibodies has been limited by the unknown binding properties of human immunoglobulins (huIgG) to porcine Fc gamma receptors (poFcγR) influencing safety and efficacy readouts. Therefore, knowing IgG-FcγR interactions in the animal model is a prerequisite for the use of minipigs in preclinical safety and efficacy studies with therapeutic antibodies.METHODS:Here, we describe the cloning and expression of poFcγRs and their interactions with free and complexed human therapeutic IgG1 by surface plasmon resonance and flow cytometry.RESULTS:We show here that poFcγRIa, poFcγRIIa, and poFcγRIIb bind huIgG1 antibodies with comparable affinities as corresponding huFcγRs. Importantly, poFcγRs bind huIgG immune complexes with high avidity, thus probably allowing human-like effector functions. However, poFcγRIIIa binds poIgG1a but not to huIgG1.CONCLUSIONS:The lack of binding of poFcγRIIIa to huIgG1 might cause underestimation of FcγRIIIa-mediated efficacy or toxicity as mediated by porcine natural killer cells. Therefore, the suitability of minipigs in preclinical studies with human therapeutic antibodies has to be assessed case by case. Our results facilitate the use of Göttingen minipigs for assessment of human therapeutic antibodies in preclinical studies.