The CD40 agonist HERA-CD40L results in enhanced activation of antigen presenting cells, promoting an anti-tumor effect alone and in combination with radiotherapy

Introduction

The ability to modulate and enhance the anti-tumor immune responses is critical in developing novel therapies in cancer. The Tumor Necrosis Factor (TNF) Receptor Super Family (TNFRSF) are potentially excellent targets for modulation which result in specific anti-tumor immune responses. CD40 is a member of the TNFRSF and several clinical therapies are under development. CD40 signaling plays a pivotal role in regulating the immune system from B cell responses to myeloid cell driven activation of T cells. The CD40 signaling axis is well characterized and here we compare next generation HERA-Ligands to conventional monoclonal antibody based immune modulation for the treatment of cancer.

Methods & results

HERA-CD40L is a novel molecule that targets CD40 mediated signal transduction and demonstrates a clear mode of action in generating an activated receptor complex via recruitment of TRAFs, cIAP1, and HOIP, leading to TRAF2 phosphorylation and ultimately resulting in the enhanced activation of key inflammatory/survival pathway and transcription factors such asNFkB, AKT, p38, ERK1/2, JNK, and STAT1 in dendritic cells. Furthermore, HERA-CD40L demonstrated a strong modulation of the tumor microenvironment (TME) via the increase in intratumoral CD8+ T cells and the functional switch from pro-tumor macrophages (TAMs) to anti-tumor macrophages that together results in a significant reduction of tumor growth in a CT26 mouse model. Furthermore, radiotherapy which may have an immunosuppressive modulation of the TME, was shown to have an immunostimulatory effect in combination with HERA-CD40L. Radiotherapy in combination with HERA-CD40L treatment resulted in an increase in detected intratumoral CD4+/8+ T cells compared to RT alone and, additionally, the repolarization of TAMs was also observed, resulting in an inhibition of tumor growth in a TRAMP-C1 mouse model.

Discussion

Taken together, HERA-CD40L resulted in activating signal transduction mechanisms in dendritic cells, resulting in an increase in intratumoral T cells and manipulation of the TME to be pro-inflammatory, repolarizing M2 macrophages to M1, enhancing tumor control.

Use of symptom-guided physical activity and exercise rehabilitation for COVID-19 and other postviral conditions

There are many similarities in symptoms between postviral conditions, including clinical features such as fatigue, reduced daily activity and postexertional symptom exacerbation. Unfavourable responses to exercise have influenced the wider debate on how to reintegrate physical activity (PA) and exercise while simultaneously managing symptoms during recovery from post-COVID-19 syndrome (or Long COVID). This has resulted in inconsistent advice from the scientific and clinical rehabilitation community on how and when to resume PA and exercise following COVID-19 illness. This article provides commentary on the following topics: (1) controversies surrounding graded exercise therapy as a treatment modality for post-COVID-19 rehabilitation; (2) evidence supporting PA promotion, resistance exercise and cardiorespiratory fitness for population health, and the consequences of physical inactivity in patients with complex rehabilitation needs; (3) population-based challenges for UK Defence Rehabilitation practitioners for the management of postviral conditions; and (4) 'symptom guided PA and exercise rehabilitation' as an appropriate treatment option for managing individuals with multifaceted medical needs.

Movement Foundations. The perceived impact of a digital rehabilitation tool for returning to fitness following a period of illness, including COVID-19 infection: a qualitative study

Digital interventions can increase physical activity (PA) levels in adults. However, the COVID-19 pandemic highlighted the complexities faced when guiding people to start or return to PA following illness or inactivity. A digital tool, Movement Foundations, was developed to provide remote guidance on building strength and capacity across functional movement patterns, with graduated progression based on user responses and input. This qualitative study aimed to explore the perceived impacts of using the tool. Nine participants aged over 35 years from the healthcare and academic healthcare sectors were recruited to use it and were subsequently interviewed. Thematic analysis identified three themes falling under the overarching concept of ‘Capability, Opportunity and Motivation—Behaviour (COM-B) Plus’, encompassing: skills and capacity for movement; opportunities, motivations and barriers for movement; and a personalised, safe space in which to develop. Participants felt that the digital tool increased their capacity and confidence in movement and positively impacted their daily activities. External factors such as illness and stress clouded perceptions of the impacts of PA. Time, work pressures and needing equipment were still considered significant barriers to PA. Still, participants appreciated the flexibility and non-prescriptive nature of the tool and felt that it helped movement to become opportunistic and habitual. Increased capacity for PA and feeling the subsequent physical and mental effects positively influenced motivation. Structure and guidance, with graduated progress, were seen as protective. Guided self-reflection helped participants understand their capacity and limitations with regard to movement and promoted motivation. Although acquiring technical skills to guide movement may be important for those recovering from illness, participants found that a structure promoting individualised guidance, graduated progression and guided self-reflection were important motivational factors for continuing use. Digital interventions should consider these aspects when seeking to promote habitual PA.

Abstract 1587: Generation and characterization of novel bispecific molecules combining single-chain-CD40L with anti-CEA, anti-CD95L or anti-PD-L1 targeting moieties

CD40 ligand is a member of the TNF superfamily (TNF-SF) and a key regulator of the immune system. Its cognate receptor CD40 is expressed on antigen-presenting cells and on many tumor types, and has emerged as an attractive target for immunological cancer treatment. We developed HERA-CD40L, a construct composed of a trivalent single-chain CD40L-receptor-binding-domain (scCD40L-RBD) linked to a silenced human IgG1-Fc-domain thereby generating a hexavalent molecule. We showed previously that HERA-CD40L mimics the natural ligand, thereby inducing potent agonistic activity which is independent of FcγR mediated crosslinking and superior to anti-CD40 benchmark antibodies. For combinatorial cancer immunotherapy we have created bispecific molecules by combining the HERA-CD40L scaffold with antibody derived domains targeting different classes of tumor associated antigens. These bispecific fusion proteins combine the potent co-stimulatory CD40-agonist with either direct tumor-cell targeting and/or additional immunomodulatory activities in the tumor microenvironment. To evaluate the different fusion protein formats, the tumor associated antigens CEA, PD-L1 and CD95L were chosen as model-targets. In addition to the hexavalent targeted HERA-CD40L, trivalent targeted fusion proteins, employing the scCD40L-RBD as building block, were created as well. All engineering prototypes were produced in CHO-S cells and purified, resulting in highly pure non-aggregating protein lots as demonstrated by SDS-PAGE and HPLC-SEC. Functional binding to their respective targets was shown by ELISA and to proof biological in vitro activity luciferase reporter gene assays were employed. The basic underlying immunological processes have been investigated in vitro. The trivalent CD40L, the trivalent CD40L-bispecifics anti-CD95L-scCD40L-RBD and anti-CEA-scCD40L-RBD as well as anti-CD40, anti-PD-L1 or anti-CD95L antibodies did not activate human monocytes, even if the antibodies were co-administered with trivalent CD40L. In contrast, the hexavalent HERA-CD40L, the hexavalent bifunctional CD40L-constructs and the trivalent anti-PD-L1-scCD40L-RBD-construct induced strong activation/maturation of the monocytes as indicated by CD83, CD86, HLA-DR upregulation which was accompanied by increased chemokine receptor (CD54, CCR7) and PD-L1 expression. When co-cultured with CD3 positive T cells, these pre-activated monocytes led to subsequent activation of CD4 as well as CD8 positive T cells, indicated by increased expression of CD25, CD69 and CD54. This clearly shows that the close proximity of anti-PD-L1 and trivalent CD40L within one molecule makes a huge difference for biological activity. Hence, these novel bispecific constructs are a promising therapeutic approach to promote anti-tumor immune responses.

Citation Format: Matthias Schroeder, Katharina Billian-Frey, Jaromir Sykora, Mauricio Redondo-Mueller, Karl Heinonen, Jamie Frankish, Christian Gieffers, Meinolf Thiemann, Oliver Hill. Generation and characterization of novel bispecific molecules combining single-chain-CD40L with anti-CEA, anti-CD95L or anti-PD-L1 targeting moieties [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1587.

Nanoscale FasL Organization on DNA Origami to Decipher Apoptosis Signal Activation in Cells

Cell signaling is initiated by characteristic protein patterns in the plasma membrane, but tools to decipher their molecular organization and activation are hitherto lacking. Among the well-known signaling pattern is the death inducing signaling complex with a predicted hexagonal receptor architecture. To probe this architecture, DNA origami-based nanoagents with nanometer precise arrangements of the death receptor ligand FasL are introduced and presented to cells. Mimicking different receptor geometries, these nanoagents act as signaling platforms inducing fastest time-to-death kinetics for hexagonal FasL arrangements with 10 nm inter-molecular spacing. Compared to naturally occurring soluble FasL, this trigger is faster and 100× more efficient. Nanoagents with different spacing, lower FasL number or higher coupling flexibility impede signaling. The results present DNA origami as versatile signaling scaffolds exhibiting unprecedented control over molecular number and geometry. They define molecular benchmarks in apoptosis signal initiation and constitute a new strategy to drive particular cell responses.

Abstract 4460: Novel bispecific molecules combining HERA-CD40L with anti-CEA or with anti-PD-L1 for targeting

CD40 ligand is a member of the TNF superfamily and a key regulator of the immune system. Its cognate receptor CD40 is expressed on antigen-presenting cells and on many tumor types, and has emerged as an attractive target for immunological cancer treatment. We have shown previously, that hexavalent HERA-CD40L is a potent CD40 agonist which is clearly superior over anti-CD40 benchmark antibodies and able to establish single agent anti-tumor immune responses both in vitro and in vivo. Since this compound qualifies as an ideal candidate for combinatorial cancer treatments we have created bispecific molecules by adding antibody derived targeting domains to the HERA-CD40L scaffold. These bispecific fusion proteins combine the potent co-stimulatory CD40-agonist with additional functionalities to enable tumor targeting and/or additional immuno-modulatory activities. To evaluate the different fusion protein formats in principle, the tumor associated antigens CEA and PD-L1 were chosen as targets. In addition to the hexavalent targeted HERA-CD40L, trivalent targeted fusion proteins employing the single-chain CD40L (scCD40L) as building block were created. Anti-CEA-HERA-CD40L, anti-CEA-trivalent scCD40L, anti-PD-L1-HERA-CD40L and anti-PD-L1-trivalent scCD40L were produced in CHO-S cells and purified resulting in highly pure non-aggregating protein lots as demonstrated by SDS-PAGE and HPLC-SEC. ELISA assays confirmed the specific binding to their targets - CD40 and CEA or CD40 and PD-L1, respectively. Employing a CD40 Luciferase reporter gene assay, hexavalent anti-CEA-HERA-CD40L showed a strong agonistic activity which was clearly superior to the anti-CEA-trivalent scCD40L- construct. Similarly, hexavalent anti-PD-L1-HERA-CD40L showed a strong agonistic activity in this assay which also was clearly superior to the anti-PD-L1-trivalent scCD40L construct. A PD-1/PD-L1 Luciferase reporter gene assay assessing the cellular activity of compounds interfering with PD-1/PD-L1 binding showed a clear activity for anti-PD-L1-HERA-CD40L. As expected for an assay assessing antagonistic activities, the activity of hexavalent anti-PD-L1-HERA-CD40L was in the same range as a reference anti-PD-L1 antibody and the anti-PD-L1-trimeric scCD40L- construct. Based on the in vitro data presented, the bispecific molecules combining HERA-CD40L with tumor targeting (anti-CEA) or with a checkpoint-blockade inhibitor (anti-PD-L1) are promising therapeutic approaches to promote anti-tumor immune responses.

Citation Format: Meinolf Thiemann, Katharina Billian-Frey, Matthias Schröder, Christian Merz, Jaromir Sykora, David M. Richards, Mauricio Redondo Müller, Julian P. Sefrin, Karl Heinonen, Christian Gieffers, Oliver Hill. Novel bispecific molecules combining HERA-CD40L with anti-CEA or with anti-PD-L1 for targeting [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 4460.

Abstract 4529: Neutralization of pro-apoptotic CD95L by Asunercept/APG101 does not impair anti-tumor immune responses

The CD95 ligand (CD95L) is frequently overexpressed in cancers and tumor-associated endothelia, but also other immune cells like MDSCs and Tregs. Binding of CD95L expressed on tumors or regulatory immune cells to activated CD95-expressing effector cells triggers activation-induced apoptosis (AICD) or impairs their proliferation. In contrast, most tumors do also express CD95, but are intrinsically resistant to CD95-induced apoptosis. Thus, CD95L in the tumor microenvironment greatly contributes to the observed immunosuppression and escape from tumor surveillance by the immune system, making CD95 a potential immune checkpoint. Asunercept (APG101) is a fully human fusion protein consisting of the extracellular domain of CD95 and the Fc-domain of human IgG1, which efficiently inhibits CD95/CD95L signaling. Clinical efficacy has been demonstrated in a controlled randomized phase 2 study in patients with recurrent glioblastoma. Here we examined the effects of APG101 on innate and adaptive immune cells and subsequent effects on tumor cell killing. Subtypes of in vitro differentiated macrophages generated with and without exposure to APG101 were functionally and phenotypically analyzed by ELISA and multi-color flow cytometry following various stimuli. APG101 did not alter differentiation patterns and response of M1- and M2-like macrophages in vitro. Direct co-culture of monocytes with tumor cells resulted in an M2/TAM-like phenotype which was not influenced by APG101, but re-programming to an M1-like state was achieved by addition of a CD40 agonist. Effects of APG101 on the proliferation and activation of CD8+ T cells in the presence of autologous CD4+ T(reg) cells and allogeneic APC was assessed by CFSE-dilution and multi-color flow cytometry, respectively. The proliferation rate of CD8 T cells in co-cultures with CD4 T(reg) cells in response to stimulation with APCs was increased in the presence of APG101. Real-time cell analysis was performed employing direct co-cultures of activated T cells and tumor cell lines. Tumor killing assays using direct co-cultures of in vitro activated T cells with and without APG101 demonstrate that tumor killing was not impaired by APG101.

Conclusion: Asunercept (APG101) is a potent inhibitor of pro-apoptotic/anti-proliferative CD95/CD95L signaling in immune cells and protects activated immune cells from activation induced cell death (AICD). Our results suggest that APG101 does not impair CD8 T cell activation, but rather supports their proliferation by disrupting CD95/CD95L interaction with regulatory T cells. Importantly, the primary anti-tumor killing mechanisms is most likely CD95L-independent and remains unaffected by the presence of APG101. The inhibition of CD95 signaling as an immune checkpoint represents an attractive and novel concept for immunologic treatment of tumors and the combination of Asunercept/APG101 with co-stimulatory TNFR-SF agonists is currently being investigated.

Citation Format: Christian Merz, Jaromir Sykora, Rebecca Hussong, Meinolf Thiemann, Oliver Hill, Christian Gieffers. Neutralization of pro-apoptotic CD95L by Asunercept/APG101 does not impair anti-tumor immune responses [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 4529.

Abstract 1076: Hexavalent HERA-CD40L induces a productive T cell-mediated anti-tumor immune response and shows superior activity in comparison to benchmark CD40 agonistic antibodies

TNF Receptor Superfamily members (TNF-R-SF), including CD40, are key regulators of the immune system and have been immunotherapeutic targets for over 20 years. CD40 signaling serves as an important co-stimulatory signal for antigen-presenting cells (APC). For the induction of a CD40 driven anti-tumor immune response multiple approaches, - most of them antibody based - are currently under investigation. However, the structural necessity of trimerization within the TNF-R-SF, defines bivalent antibodies generally as unfeasible inducers of signaling events within this protein family. To overcome the known inadequacies of antibodies, we developed HERA-CD40L, composed of two trivalent CD40L-receptor-binding domains, fused to a silenced human IgG1 Fc-domain. This hexavalent CD40 agonist mimics the natural ligand and enables efficient receptor clustering and superior signaling. HERA-CD40L treatment increased the pro-inflammatory state of all CD40-expressing cells examined. It promoted the licensing of dendritic cells (DC), macrophages, B cells and other APC. Comparison to benchmark antibodies revealed that HERA-CD40L elicited a stronger and more rapid activation of NFκB signaling in primary B cells. HERA-CD40L treatment, but not clinical benchmark antibodies triggered immediate NFκB, MAPK, PI3K and STAT-1 signaling in primary monocyte-derived immature DC. As a result, HERA-CD40L induced upregulation of activation markers and co-stimulatory molecules in B cells and DC. Using SEC fractionation followed by a CD40 reporter assay, we could furthermore demonstrate that the activity of a clinical benchmark antibody derived exclusively from antibody aggregates. In vitro HERA-CD40L treatment converted immature phagocytic macrophages into mature/professional APC and induced repolarization of M2- to M1-like macrophages. These findings were confirmed in vivo using a mouse surrogate (mmHERA-CD40L). Upon treatment of MC38-CEA and CT26wt syngeneic mouse models, we observed single agent anti-tumor efficacy. In the CT26wt model, mmHERA-CD40L treatment converted cold into hot tumors by increasing T cell infiltration. Furthermore, mmHERA-CD40L induced a strong dose dependent decrease of tumor associated pro-tumorigenic M2-macrophages indicating a profound reorganization of the tumor microenvironment. Both in vitro (human) and in vivo (mouse), HERA-CD40L increased antigen-specific immune system activation without affecting the non-specific immune cells. These data, together with pilot PD/safety results, demonstrate that the activity of HERA-CD40L is both potent and safe. In conclusion, HERA-CD40L is a potent agonist able to show single agent anti-tumor activity. The biological activity is distinct from and superior to clinical benchmark “agonistic” antibodies. HERA-CD40L has a well-defined mechanism of action, does not depend on Fc gamma receptor-mediated crosslinking and hence functions as a true agonist.

Citation Format: Christian Gieffers, David M. Richards, Jaromir Sykora, Christian Merz, Julian P. Sefrin, Katharina Billian-Frey, Karl Heinonen, Mauricio Redondo Müller, Matthias Schröder, Meinolf Thiemann, Oliver Hill. Hexavalent HERA-CD40L induces a productive T cell-mediated anti-tumor immune response and shows superior activity in comparison to benchmark CD40 agonistic antibodies [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 1076.

Concepts for agonistic targeting of CD40 in immuno-oncology

TNF Receptor Superfamily (TNF-R-SF) signaling is a structurally well-defined event that requires proper receptor clustering and trimerization. While the TNF-SF ligands naturally exist as trivalent functional units, the receptors are usually separated on the cell surface. Critically, receptor assembly into functional trimeric signaling complexes occurs through binding of the natural ligand unit. TNF-R-SF members, including CD40, have been key immunotherapeutic targets for over 20 years. CD40, expressed by antigen-presenting cells, endothelial cells, and many tumors, plays a fundamental role in connecting innate and adaptive immunity. The multiple investigated strategies to induce CD40 signaling can be broadly grouped into antibody-based or CD40L-based approaches. Currently, seven different antibodies and one CD40L-based hexavalent fusion protein are in active clinical trials. In this review, we describe the biology and structural properties of CD40, requirements for agonistic signal transduction through CD40 and summarize current attempts to exploit the CD40 signaling pathway for the treatment of cancer.

HERA-GITRL activates T cells and promotes anti-tumor efficacy independent of FcγR-binding functionality

Background

Glucocorticoid-induced TNFR-related protein (TNFRSF18, GITR, CD357), expressed by T cells, and its ligand (TNFSF18, GITRL), expressed by myeloid populations, provide co-stimulatory signals that boost T cell activity. Due to the important role that GITR plays in regulating immune functions, agonistic stimulation of GITR is a promising therapeutic concept. Multiple strategies to induce GITR signaling have been investigated. The limited clinical efficacy of antibody-based GITR agonists results from structural and functional characteristics of antibodies that are unsuitable for stimulating the well-defined trimeric members of the TNFRSF.

Methods

To overcome limitations of antibody-based TNFRSF agonists, we have developed HERA-GITRL, a fully human hexavalent TNF receptor agonist (HERA) targeting GITR and mimicking the natural signaling concept. HERA-GITRL is composed of a trivalent but single-chain GITRL-receptor-binding-domain (scGITRL-RBD) unit fused to an IgG1 derived silenced Fc-domain serving as dimerization scaffold. A specific mouse surrogate, mmHERA-GITRL, was also generated to examine in vivo activity in respective mouse tumor models.

Results

For functional characterization of HERA-GITRL in vitro, human immune cells were isolated from healthy-donor blood and stimulated with anti-CD3 antibody in the presence of HERA-GITRL. Consistently, HERA-GITRL increased the activity of T cells, including proliferation and differentiation, even in the presence of regulatory T cells.

In line with these findings, mmHERA-GITRL enhanced antigen-specific clonal expansion of both CD4+ (OT-II) and CD8+ (OT-I) T cells in vivo while having no effect on non-specific T cells. In addition, mmHERA-GITRL showed single-agent anti-tumor activity in two subcutaneous syngeneic colon cancer models (CT26wt and MC38-CEA). Importantly, this activity is independent of its FcγR-binding functionality, as both mmHERA-GITRL with a functional Fc- and a silenced Fc-domain showed similar tumor growth inhibition.

Finally, in a direct in vitro comparison to a bivalent clinical benchmark anti-GITR antibody and a trivalent GITRL, only the hexavalent HERA-GITRL showed full biological activity independent of additional crosslinking.

Conclusion

In this manuscript, we describe the development of HERA-GITRL, a true GITR agonist with a clearly defined mechanism of action. By clustering six receptor chains in a spatially well-defined manner, HERA-GITRL induces potent agonistic activity without being dependent on additional FcγR-mediated crosslinking.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0671-4) contains supplementary material, which is available to authorized users.

Abstract 4845: HERA-CD27L, a true CD27 agonist, is a hexavalent CD27 ligand that enhances T cell activation and induces potent anti-tumor immunity

Agonistic stimulation of TNFRSF members like CD27 is a promising strategy to boost anti-tumor responses. Although antibodies are effective inhibitors of signaling, they have shown minimal agonistic activity due to their limited binding domains, flexibility and the toxicity mediated by Fc/FcγR interactions. TNFRSF signaling is a structurally well-defined event that takes place during cell contact. The trimeric-trivalent TNFSF-receptor binding domain (TNFSF-RBD) on the conducting cell and the resulting multi-trimer-based receptor clustering on the receiving cell are essential for signaling. In contrast to antibodies, HERA-CD27L mimics the natural ligand and induces potent activity. In order to understand the activity of HERA-CD27L, human T cells were stimulated in the presence of HERA-CD27L, the trimeric CD27L or a clinical benchmark anti-CD27 antibody. In all assays, treatment with the hexavalent HERA-CD27L significantly boosted T cell activation, proliferation and differentiation. Furthermore, the hexavalent molecule was always superior to the trimeric CD27L and bivalent antibody. In fact, treatment with the anti-CD27 antibody resulted in significantly weaker proliferation compared to anti-CD3 antibody alone. To understand early events, we tested CD27 signaling using a reporter cell assay. Treatment with HERA-CD27L and CD27L resulted in high and intermediate, respectively, reporter activity. In contrast, the anti-CD27 antibody failed to show any signaling activity across a wide range of concentrations. Since most T cells express CD27, there is potential for non-specific T cell activation. This was examined by comparing OVA-specific and non-specific T cells in the same environment using the CD8+ “OT-I” T cell adoptive transfer mouse model. Following a single dose of HERA-CD27L, serial blood samples showed a significant and HERA-CD27L dose-dependent clonal expansion of OT-I T cells. OT-I T cells expressed high levels of activation markers, while the endogenous T cells failed to show any response. The potent single-agent anti-tumor efficacy of the hexavalent HERA-CD27L was demonstrated in two different mouse models. With CT26wt, HERA-CD27L also showed superior activity compared to anti-PD-1 antibody. Furthermore, combination of HERA-CD27L and anti-PD-1 antibody showed additive effects. Finally, early treatment with HERA-CD27L significantly increased overall survival, from 19 to 41 days, and tumor-free animals still alive at the end of the study were protected from tumor re-challenge. Various strategies have been proposed for targeting CD27 for cancer therapy. As we have shown here, the hexavalent HERA-CD27L has superior activity compared to bivalent antibodies. Altogether, HERA-CD27L shows single-agent anti-tumor efficacy, is well tolerated by multiple relevant species and the lead candidate is currently ready for GMP cell line development.

Citation Format: Julian P. Sefrin, David M. Richards, Katharina Billian-Frey, Karl Heinonen, Viola Marschall, Christian Merz, Mauricio Redondo Müller, Matthias Schröder, Jaromir Sykora, Meinolf Thiemann, Harald Fricke, Christian Gieffers, Oliver Hill. HERA-CD27L, a true CD27 agonist, is a hexavalent CD27 ligand that enhances T cell activation and induces potent anti-tumor immunity [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 4845.

A Single-Chain-Based Hexavalent CD27 Agonist Enhances T Cell Activation and Induces Anti-Tumor Immunity

Tumor necrosis factor receptor superfamily member 7 (TNFRSF7, CD27), expressed primarily by T cells, and its ligand CD27L (TNFSF7, CD70) provide co-stimulatory signals that boost T cell activation, differentiation, and survival. Agonistic stimulation of CD27 is therefore a promising therapeutic concept in immuno-oncology intended to boost and sustain T cell driven anti-tumor responses. Endogenous TNFSF/TNFRSF-based signal transmission is a structurally well-defined event that takes place during cell-to-cell-based contacts. It is well-established that the trimeric-trivalent TNFSF-receptor binding domain (TNFSF-RBD) exposed by the conducting cell and the resulting multi-trimer-based receptor clustering on the receiving cell are essential for agonistic signaling. Therefore, we have developed HERA-CD27L, a novel hexavalent TNF receptor agonist (HERA) targeting CD27 and mimicking the natural signaling concept. HERA-CD27L is composed of a trivalent but single-chain CD27L-receptor-binding-domain (scCD27L-RBD) fused to an IgG1 derived silenced Fc-domain serving as dimerization scaffold. The hexavalent agonist significantly boosted antigen-specific T cell responses while having no effect on non-specific T cells and was superior over stabilized recombinant trivalent CD27L. In addition, HERA-CD27L demonstrated potent single-agent anti-tumor efficacy in two different syngeneic tumor models, MC38-CEA and CT26wt. Furthermore, the combination of HERA-CD27L and an anti-PD-1 antibody showed additive anti-tumor effects highlighting the importance of both T cell activation and checkpoint inhibition in anti-tumor immunity. In this manuscript, we describe the development of HERA-CD27L, a true CD27 agonist with a clearly defined forward-signaling mechanism of action.

Abstract 1760: The hexavalent CD40 agonist HERA-CD40L augments multi-level crosstalk between T cells and antigen-presenting cells

Introduction: HERA-CD40L is a novel hexavalent CD40 agonist engineered with the HERA-Technology developed by Apogenix. We have previously shown that the natural binding mode via the receptor/ligand binding domains and the high clustering capacity for the cognate receptor clearly distinguish HERA-CD40L from other, e.g. antibody-based, CD40-targeting compounds. Here, we report on the effects of HERA-CD40L on crosstalk between T cells and antigen presenting cells (APC) and the functional consequences in vitro. Materials & Methods: Biological activity of CD40 agonists was analyzed using co-cultures of primary T cells with B cells or monocytes/macrophages. All primary cells were isolated by negative selection using magnetic sorting from healthy donor buffy coats. Expression of CD markers upon CD40 ligation on B cells and monocytes was analyzed by flow cytometry (FC). Monitoring of T cell-induced killing of tumor cells primed in direct co-cultures with APC was done on a real-time cell analysis system (xCELLigence). For analysis of phagocytosis, we developed an FC-based assay employing primary monocytes/macrophages and Jurkat A3 cells. Results: Treatment of primary B cells and monocytes with HERA-CD40L induced expression of co-stimulatory molecules, like CD86, and promotes M1 maturation of naïve (M0) monocytes. In vitro, treatment of alternatively activated M2 macrophages with HERA-CD40L induced an M2 to M1 phenotype switch (re-programming) which concurs with CD16 downregulation and a dose-dependent decrease of phagocytic activity of re-programmed macrophages compared to M0 or M2 macrophages. Primary B cells and M1 macrophages enhanced the proliferation and cytotoxic activity of naïve T cells in direct co-cultures in the presence of HERA-CD40L. The activating effect on T cells required direct cell-cell contact with APC and was not observed in indirect co-cultures. Functionally, neutralization of either MHC-I or CD80/CD86 in direct co-cultures inhibited full activation of the T cells in vitro as shown by kill assays with various tumor cell lines. Conclusion: The hexavalent CD40 agonist HERA-CD40L produced by the Apogenix HERA-Technology is a potent immune-regulator acting on B cells and myeloid cells. HERA-CD40L promotes activation of B cells, maturation of APC and induces an M2 to M1 phenotype switch which inhibits tolerance-inducing phagocytic activity of the repolarized macrophages in vitro. In response to CD40 ligation on APC, an efficient anti-tumor response is conferred to primary T cells through cell-cell interactions via MHC-I and CD80/CD86.

Citation Format: Christian Merz, Jaromir Sykora, Viola Marschall, David M. Richards, Meinolf Thiemann, Harald Fricke, Oliver Hill, Christian Gieffers. The hexavalent CD40 agonist HERA-CD40L augments multi-level crosstalk between T cells and antigen-presenting cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1760.

Abstract 3754: The novel hexavalent human CD137/4-1BB agonist HERA-CD137L promotes anti-cancer immunity by activating CD8 T cells while regulatory T cells are not affected

CD137/4-1BB is an inducible costimulatory receptor mainly expressed on immune cells following activation. Binding of the cognate ligand CD137L/4-1BBL leads to receptor trimerization and activation of signaling cascades involved in expansion and survival of T cells and myeloid cells as well as memory formation and protection against autoimmunity. Apogenix´ HERA technology is based on trivalent single-chain molecular mimics of the TNF-SF receptor binding domains fused to a silenced human IgG1-Fc-domain which serves exclusively as a dimerization scaffold. This results in hexavalent agonists replicating the natural receptor binding mode. Due to their inherent high receptor clustering capacity, HERA compounds are true agonists and their biological activity is, in contrast to bivalent anti-TNFR-SF antibodies, independent of FcR-mediated crosslinking events. HERA-CD137L was produced in CHO-S cells and purified resulting in highly pure non-aggregating protein lots. PK studies in mice demonstrated a terminal half-life of 75 hours indicating excellent in vivo stability. To study the effects on immune cells in vitro, T cells were isolated from healthy-donor buffy coats and stimulated with anti-CD3 antibody alone or in combination with HERA-CD137L. Using multicolor flow cytometry, we confirmed that expression of CD137 increased on CD8+ T cells following stimulation with anti-CD3 antibody. In accord with upregulation of the activation markers CD25 and CD69 and the memory marker CD45RO, treatment with HERA-CD137L enhanced proliferation of both CD4+ and CD8+ T cells, as determined by CFSE analysis. Intracellular accumulation of IFN-γ, TNF-α, Granzyme B and Perforin upon CD137 ligation was observed in CD8+ but not CD4+ T cells. HERA-CD137L treatment of THP-1 monocytes co-cultured with primary T cells also increased their cytotoxic activity against multiple tumor cell lines, including colorectal and mammary, as shown in a real-time live cell analysis (RTCA) assay. Primary human monocytes express low levels of CD137 and differentiation to macrophages in vitro did not increase expression. However, pro-inflammatory cytokines such as TNF-α and the chemokine CCL4 were secreted after stimulation with HERA-CD137L. RTCA assays further demonstrated enhanced antigen-specific killing of MDA-MB231 tumor cells by HERA-CD137L treated T cells. HERA-CD137L conveys its activity through effector T cell proliferation while regulatory T (Treg) cell proliferation or production of anti-inflammatory cytokines are not altered in Treg cell cultures. In contrast, HERA-CD137L prevented Treg-mediated suppression of effector T cells. Based on the in vitro data presented, HERA-CD137L is a promising candidate to promote anti-tumor immune responses either as single agent or in combination with other IO-compounds.

Citation Format: Meinolf Thiemann, Jaromir Sykora, David M. Richards, Christian Merz, Viola Marschall, Mauricio Redondo Mueller, Julian P. Sefrin, Karl Heinonen, Harald Fricke, Christian Gieffers, Oliver Hill. The novel hexavalent human CD137/4-1BB agonist HERA-CD137L promotes anti-cancer immunity by activating CD8 T cells while regulatory T cells are not affected [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3754.

Abstract 630: Novel hexavalent HVEM agonist HERA-LIGHT promotes T cell activation and expansion

The tumor necrosis factor superfamily (TNFSF) member LIGHT (TNFSF14) plays an important role in regulating the activity of immune cells, especially T cells. Several studies have shown that engagement of HVEM (herpesvirus entry mediator), one of the known receptors of LIGHT, can deliver a co-stimulatory signal to support T cell activation and expansion and promote tumor clearance. The HERA technology platform developed by Apogenix generates fully human hexavalent TNFSF fusion proteins that mimic the natural receptor binding mode in order to co-stimulate T cells. HERA ligands are pure agonists whose signaling capacity does not rely on secondary Fcγ-receptor crosslinking. Here we report the in vitro and in vivo properties of a novel HERA-LIGHT construct. Similar to all HERA fusion proteins, HERA-LIGHT has been engineered as a perfect molecular mimic of the natural ligand with high clustering capacity for the cognate receptor. The core unit consists of a single chain polypeptide comprising the three minimal LIGHT-subsequences necessary for folding into a functional trivalent receptor binding domain (RBD). By fusing a silenced IgG1 Fc-domain as a dimerization scaffold to the C-terminus of the RBD we generated HERA-LIGHT, a hexavalent fusion protein. HERA-LIGHT was expressed in CHO suspension cells followed by a lab-scale purification process including AFC- and SEC-based polishing, resulting in homogenous, aggregate-free protein lots. HERA-LIGHT was proven to bind both the human and murine HVEM receptor, as determined by ELISA. Qualitative analytics revealed excellent stability following heat- and pH-stress as well as freeze-thaw cycles. Analyzing serum samples from a PK study in CD1-mice, the terminal half-life of the compound was 36.5 hours. This short half-life, relative to antibodies, allows for fast-in/fast-out dynamics essential for improving combination therapy and reducing serious side effects associated with immune system overstimulation. In order to test biological activity, T cells were isolated by magnetic sorting from human PBMCs and treated with HERA-LIGHT in vitro. Flow cytometric analysis revealed that HERA-LIGHT enhanced activation and proliferation of naïve effector T cells (Teff) following stimulation with anti-CD3 antibody, as determined by CFSE dilution. Importantly, co-stimulation with HERA-LIGHT prevented regulatory T cell (Treg)-mediated suppression of Teff proliferation. In vivo, treatment with a murine surrogate of HERA-LIGHT resulted in significant tumor growth inhibition in a pilot study using the syngeneic CT-26 colorectal cancer model.In summary, the unique hexavalent design of HERA-LIGHT mediates efficient co-stimulation of Teff even in the presence of Treg cells and independent of secondary crosslinking events. Being true agonists, all HERA molecules are unique from current antibody-based concepts rendering them attractive candidates for cancer immunotherapy.

Citation Format: Julian P. Sefrin, David M. Richards, Jaromir Sykora, Meinolf Thiemann, Christian Merz, Viola Marschall, Mauricio Redondo Müller, Karl Heinonen, Harald Fricke, Christian Gieffers, Oliver Hill. Novel hexavalent HVEM agonist HERA-LIGHT promotes T cell activation and expansion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 630.

The novel TRAIL-receptor agonist APG350 exerts superior therapeutic activity in pancreatic cancer cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has raised attention as a novel anticancer therapeutic as it induces apoptosis preferentially in tumor cells. However, first-generation TRAIL-receptor agonists (TRAs), comprising recombinant TRAIL and agonistic receptor-specific antibodies, have not demonstrated anticancer activity in clinical studies. In fact, cancer cells are often resistant to conventional TRAs. Therefore, in addition to TRAIL-sensitizing strategies, next-generation TRAs with superior apoptotic activity are warranted. APG350 is a novel, highly potent TRAIL-receptor agonist with a hexavalent binding mode allowing the clustering of six TRAIL-receptors per drug molecule. Here we report on preclinical in vitro and in vivo studies testing the activity of APG350 on pancreatic ductal adenocarcinoma (PDAC) cells. We found that APG350 potently induced apoptosis of Colo357, PancTuI and Panc89 cells in vitro. In addition, APG350 treatment activated non-canonical TRAIL signaling pathways (MAPK, p38, JNK, ERK1/ERK2 and NF-κB) and induced the secretion of IL-8. Stable overexpression of Bcl-xL inhibited APG350-induced cell death and augmented activation of non-canonical pathways. Intriguingly, pre-treatment of Bcl-xL-overexpressing cells with the BH3-mimic Navitoclax restored their sensitivity to APG350. To study the effects of APG350 on PDAC cells in vivo, we applied two different orthotopic xenotransplantation mouse models, with and without primary tumor resection, representing adjuvant and palliative treatment regimes, respectively. APG350 treatment of established tumors (palliative treatment) significantly reduced tumor burden. These effects, however, were not seen in tumors with enforced overexpression of Bcl-xL. Upon primary tumor resection and subsequent APG350 treatment (adjuvant therapy), APG350 limited recurrent tumor growth and metastases. Importantly, therapeutic efficacy of APG350 treatment was more effective compared with treatment with soluble TRAIL in both models. In conclusion, APG350 represents a promising next-generation TRA for the treatment of PDAC. Moreover, our results suggest that combining APG350 with Navitoclax might be a succesfull strategy for cancers harboring mitochondrial apoptosis resistance.

Abstract 4963: Novel hexavalent GITR agonists stimulate T cells and enhance memory formation

Introduction: The co-stimulatory receptor GITR plays an important role in initiating the immune response in the lymph nodes and in maintaining the immune response in the tumor tissue. Binding of GITR to its natural ligand directly leads to increased anti-tumor T cell activation and their survival. It also reduces the suppressive abilities of Treg cells, further increasing the anti-tumor immune response. The HERA-technology developed by Apogenix targets the TNF-receptor superfamily and generates fully human hexavalent fusion proteins with high clustering capacity for the cognate receptor. Hexavalent HERA-ligands are pure agonists whose signaling capacity is independent of secondary Fcγ-receptor crosslinking. Here we report in vitro and in vivo properties of novel hexavalent HERA-GITRL constructs.

Experimental procedures: For the assessment of in vivo stability, serum samples from a PK study with three HERA-GITRL constructs in CD1-mice were analyzed with respect to their drug levels employing a specific ELISA assay. For functional characterization of HERA-GITRL in vitro, immune cells were isolated from healthy-donor blood samples and profiled by multicolor flow cytometry (MC-FC). Subsequently, immune cells were cultured in growth media containing different HERA-GITRL constructs and anti-CD3. Changes in activation and memory markers on T cells (e.g. CD25, CD69, CD45RA, CD45RO), their proliferation rate (CFSE assay) and the intracellular staining of cytokines (e.g. TNF-α and IFN-γ) was assessed by MC-FC.

Results: Minor modifications led to three HERA-GITRL drug candidates with unique pharmacokinetic properties / in vivo stability as explored in mice. Terminal half-life was between 61.7 and 200.6 hours. Stimulation of pan T cells as well as naïve CD4+ T-lymphocytes by anti-CD3 was further augmented by HERA-GITRL as demonstrated by CD69 and CD25 expression. This effect was accompanied by an increased proliferation and an increased memory formation. Furthermore, we observed an increased level of intracellular TNF-α and IFN-γ in naïve CD4+ T-lymphocytes incubated with anti-CD3 that could be further raised by the addition of HERA-GITRL.

Conclusion: HERA-GITRL demonstrate excellent in vivo stability. Their ability to enhance proliferation and activation of naïve CD4+ T cells and to induce memory formation render them as attractive candidates for immunotherapeutic treatments of cancer.

Citation Format: Meinolf Thiemann, Christian Gieffers, David M. Richards, Christian Merz, Karl Heinonen, Mauricio Redondo Mueller, Viola Marschall, Jaromir Sykora, Harald Fricke, Oliver Hill. Novel hexavalent GITR agonists stimulate T cells and enhance memory formation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4963. doi:10.1158/1538-7445.AM2017-4963

Abstract 1688: HERA-CD40L: A novel hexavalent CD40 agonist with superior biological activity

Introduction: Targeted therapeutics for cancer treatment are mostly developed as antibodies, however, the natural signaling complexes of the members of the TNF superfamily and their receptors consist of clusters of trimers. Consequently, most of these bivalent agonistic antibodies depend on Fc receptor mediated crosslinking for biological activity. The HERA-Technology developed by Apogenix generates hexavalent fusion proteins targeting the TNF-receptor superfamily with high clustering capacity for the cognate receptor, which overcomes this disadvantage of antibody-based drugs. Here we compared the efficacy of different CD40 agonist formats, including the novel HERA-CD40L and the functional consequences of differential receptor clustering.

Materials & Methods: Biological activity of CD40 agonists was compared using an engineered reporter cell line and by flow cytometric analysis of CD40-induced IκBα degradation in Ramos B cells. T lymphocytes and monocytes were isolated from buffy coats and expression of CD markers upon CD40 ligation was analysed by multicolor flow cytometry (MC-FC). Secretion of cytokines in response to CD40 ligation was determined by ELISA. Monitoring of T cell-induced killing of tumor cells in direct co-cultures employed a real-time cell analysis system (xCELLigence).

Results: Direct comparison of bivalent CD40 antibodies with trivalent CD40L and the hexavalent HERA-CD40L in two independent bioactivity assay formats demonstrated that only the hexavalent agonist was fully active without additional crosslinking. In contrast to HERA-CD40L, neither the bivalent agonistic CD40 antibody nor the trivalent CD40L were able to upregulate expression of activation markers on B cells or to induce secretion of proinflammatory cytokines such as IL-12 and TNFα by PBMCs. In vitro generated M2-macrophages acquired an M1 phenotype and enhanced proliferation of naïve CD4+ T cells in direct co-culture. Similarly, direct co-culture of CD4+ T cells with Ramos B cells in the presence of HERA-CD40L induced cytotoxic activity of CD4+ cells against tumor cells. The activating effect was dependent on cell-cell contacts and was not observed in indirect co-cultures. Importantly, only the hexavalent HERA-CD40L showed full biological activity without additional crosslinking.

Conclusion: The hexavalent CD40 agonist HERA-CD40L produced by Apogenix HERA-Technology platform triggers CD40 signaling on B cells and cells of the monocytic lineage, leads to direct cytolytic activation and proliferation of CD4+ T cells and shifts the M1/M2 balance towards proinflammatory conditions. Unlike bivalent CD40 antibodies or trivalent CD40L_ based agonists, the hexavalent HERA-CD40L forms highly clustered signaling complexes and thus exhibits superior biological activity over other agonistic formats without the need for Fc receptor mediated crosslinking.

Citation Format: Christian Merz, Jaromir Sykora, Meinolf Thiemann, Viola Marschall, Karl H. Heinonen, Harald Fricke, Christian Gieffers, Oliver Hill. HERA-CD40L: A novel hexavalent CD40 agonist with superior biological activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1688. doi:10.1158/1538-7445.AM2017-1688

Abstract 4690: Hexavalent CD27 agonists show single agent anti-tumor activity and enhanced memory formation in mouse syngeneic tumor models

Tumor necrosis factor receptor superfamily (TNFRSF) proteins are widely expressed by immune and tumor cells highlighting their importance in multiple locations and phases of the anti-tumor immune response. Apogenix has developed a proprietary technology platform for the construction of novel hexavalent TNFRSF agonists (HERA) for the treatment of cancer. HERA fusion proteins comprise a perfect molecular mimic of the TNFSF cytokine structure and are based on dimerization of trivalent single-chain TNFSF receptor-binding domains (scTNFSF-RBD) via a Fc-γ receptor (FcγR) binding deficient immunoglobulin Fc domain. As a result of this molecular design, HERA proteins are capable of clustering six receptors in a spatially well-defined manner. Signaling following treatment with the Apogenix HERA “scTNFSF-RBD-Fc fusion proteins” is entirely independent of secondary crosslinking through FcγRs that is required for many agonistic anti-TNFRSF antibodies. The HERA engineering concept has been successfully translated to TRAIL, GITRL, CD40L, LIGHT and CD27L resulting in agonists that are currently in development. CD27L is a potent co-stimulatory molecule that drives T cell activation and survival through interaction with its receptor (CD27). HERA-CD27L is expressed in CHO suspension cells followed by a lab-scale purification process that results in homogenous aggregate-free protein lots. The purified protein binds its respective target-receptor with high affinity. In vitro, HERA-CD27L was able to bind CD27 expressed on primary human CD4+ and CD8+ T cells. Binding significantly increased T cell expansion following αCD3/αCD28 stimulation and leads to increased expression of OX40 on CD4+ T cells and 4-1BB on CD8+ T cells, respectively. In vivo, a single dose of 10mg/kg HERA-CD27L increases clonal expansion of antigen-specific CD8+ T cells upon immunization with Ovalbumin (Ova) in the mouse OT-1 model with a kinetics leading to peak levels of >25% Ova-specific CD8+ T cells at day 6 after treatment. Anti-tumor efficacy of HERA-CD27 was evaluated in MC38-CEA and CT26 colorectal syngeneic murine tumor models. In both models treatment with HERA-CD27L resulted in a dose dependent inhibition of tumor growth. CT26 tumor bearing mice treated with 1mg/kg HERA-CD27L, twice weekly showed an 85% tumor-growth inhibition (TGI) compared to the control group. A significant TGI of 48% could be observed in the MC38-CEA model upon treatment with 10mg/kg, twice weekly. Analysis of peripheral lymphoid tissues in the MC38-CEA bearing mice could furthermore show that HERA-CD27L treatment is accompanied with enhanced memory formation in both CD4+ & CD8+ T cells. In summary, the data on the hexavalent HERA-CD27L indicate a potent immune cell driven anti tumor efficacy. Therefore, HERA-CD27 agonists could be applied for the treatment of cancer as a single agent or in combination with check-point Inhibitors.

Citation Format: Christian Gieffers, David Richards, Jaromir Sykora, Mauricio Redondo-Müller, Meinolf Thiemann, Christian Merz, Karl Heinonen Heinonen, Viola Marschall, Harald Fricke, Oliver Hill. Hexavalent CD27 agonists show single agent anti-tumor activity and enhanced memory formation in mouse syngeneic tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4690. doi:10.1158/1538-7445.AM2017-4690

Abstract A83: Hexavalent agonists targeting co-stimulatory receptors of the tumor necrosis factor superfamily

Tumor necrosis factor receptor superfamily (TNFRSF) proteins are widely expressed by immune and tumor cells highlighting their importance in multiple locations and phases of the anti-tumor immune response. Whereas agonistic stimulation of TRAIL-Receptor-1 or -2 can directly induce apoptosis in tumor cells, signaling through many TNFRSF members, such as CD40, CD27, OX40, HVEM, GITR and 4-1BB, results in co-stimulation of immune cells. Therefore, agonistic stimulation of certain members of the TNFRSF is considered to have a positive impact on immune-based therapeutic concepts in clinical oncology. Apogenix has developed a proprietary technology platform for the construction of novel hexavalent TNFRSF agonists (HERA) for the treatment of cancer. HERA fusion proteins are based on a perfect molecular mimic of the TNFSF cytokine structure. The HERA core unit consists of one single polypeptide chain comprising the three receptor-binding domain-forming subsequences (TNFSF-protomers). These single-chain TNFSF receptor-binding domains (scTNFSF-RBD) preserve the structural organization of the trimeric natural TNFSF cytokine and can be utilized to engineer fully human fusion-proteins in a modular manner. Fusing an IgG1 Fc-domain as a dimerization scaffold to the C-terminus of a scTNFSF-RBD creates a hexavalent agonist from two trivalent scTNFSF-RBDs. As a result of this molecular design, each molecule is capable of clustering six receptors in a spatially well-defined manner in close proximity to each other. Therefore, signaling following treatment with the Apogenix HERA scTNFSF-RBD-Fc fusion proteins in vivo is independent of secondary clustering through Fc-γ receptors that is required for many agonistic anti-TNFRSF antibodies (e.g., anti-TRAIL-R2 or anti-CD40). The described HERA engineering concept has been successfully translated to TRAIL, CD40L, LIGHT and CD27L resulting in hexavalent agonists suitable for further development. CD27-Ligand is a potent co-stimulatory molecule that drives T-cell activation and survival through interaction with its receptor (CD27). Here we show in vitro and in vivo data for APG1293 (scCD27L-RBD-Fc), a hexavalent CD27 agonist. APG1293 was expressed in CHO suspension cells followed by a lab-scale purification process including affinity chromatography and SEC-based polishing, resulting in homogenous aggregate-free protein lots. The purified protein binds its respective target-receptor with high affinity. In vivo stability/PK studies have been performed in addition to in vitro experiments with primary human and mouse lymphoid and myeloid cell populations. Specifically, APG1293 was able to bind CD27 expressed on primary human CD4+ and CD8+ T cells and importantly, binding significantly increased T-cell expansion following activation. In vivo the efficacy of APG1293 was evaluated in the colorectal syngeneic murine tumor models MC38-CEA and CT26. In both models APG1293 treatment resulted in a dose dependent tumor growth inhibition. In summary, the data on the hexavalent APG1293 indicate a potent immune cell driven anti tumor efficacy. Therefore, APG1293 could be applied as a single agent or in combination with check-point inhibitors.

Citation Format: Christian Gieffers, Christian Merz, David Richards, Mauricio Redondo, Viola Marschall, Jaromir Sykora, Meinolf Thiemann, Harald Fricke, Oliver Hill. Hexavalent agonists targeting co-stimulatory receptors of the tumor necrosis factor superfamily. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A83.

Abstract B48: Structure to function: comparison of CD40 agonist formats reveals superior immune-modulating properties of hexavalent scCD40L-RBD-Fc fusion protein APG1233

Introduction: Initiation and perpetuation of anti-tumor responses of the immune system are in the focus of current approaches to fight cancer. Manipulation of the tumor microenvironment, e.g. shifting the M1/M2 ratio towards M1 is one goal to support immunologic cancer treatment. Here we examined and compared the functional effects of bivalent agonistic anti-CD40 antibodies, homo-trimeric trivalent CD40-Ligand and the novel hexavalent CD40-agonist APG1233 on the maturation and differentiation of primary monocytes, B cells and T cell mediated tumor cell killing.

Materials and Methods: Following treatment with various CD40 agonists, cytokine secretion by monocytes, PBMCs and T cells from blood samples was assessed by ELISA. Monocytes isolated from healthy-donor blood samples were differentiated in vitro into either M1- or M2-type macrophages, or dendritic cells (DC) which was confirmed by multicolor flow-cytometry (MC-FC). Subsequently, we analyzed the respective M1- and M2-type macrophages and DCs regarding their ability to induce proliferation in a direct allogenic co-culture system with naïve CD4-positive T cells by a flow cytometry-based CFSE-assay. Macrophage plasticity, e.g. re-polarisation of M2-like to M1-like macrophages upon exposure to CD40 agonists was assessed by MC-FC. A real-time cell analysis system (Roche xCelligence RTCA DP) was used to attest T cell activation by CD40 stimulated B cells, resulting in killing of tumor cells in direct co-cultures.

Results: Stimulation of CD40 on PBMCs, T cells and monocytes increased secretion of cytokines (e.g. IL-12, TNFαa, CCL4) dependent on the agonist format and moreover was strictly dependent on Fc-crosslinking when using agonistic anti-CD40 mAb. In vitro, when the hexavalent APG1233 was added to the cytokine cocktail during the in vitro differentiation process, the appearance of M1-type macrophages was substantially increased. Moreover, M2-macrophages underwent conversion and acquired M1-type surface markers after exposure to APG1233. Finally, in direct co-culture of the in vitro differentiated cell populations with naïve CD4+ T cells, M1-macrophages induced strong lymphocyte proliferation, while the induction by monocytes and M2-macrophages was low. On a functional level, T lymphocytes co-cultured with M1 or DC acquired direct cytotoxic activity against tumor cells in a real-time cell analysis assay. Similarly, induction of cytolytic activity of purified T cells in vitro required the presence of both CD40 expressing B cells and APG1233.

Conclusion: Stimulation of CD40 on immune cells triggers development of anti-tumor responses, but efficacy of various agonist formats dramatically varies. Compared to trimeric CD40L formats and agonistic anti-CD40 mAbs, the novel hexavalent CD40 agonist APG1233 emerging from Apogenix HERA Technology platform excels as a strong inducer of B cell activation, M1-type macrophage differentiation and M2->M1 conversion. M1-macrophages generated in vitro are functional and enhance proliferation of naïve CD4+ T cells. CD40 stimulation on a CD40 expressing B cell line enhances its ability to activate T cells and trigger an anti-tumor response.

Citation Format: Christian Merz, Jaromir Sykora, Thamara Beyer, Stefanie Knorn, Harald Fricke, Christian Gieffers, Oliver Hill, David M. Richards. Structure to function: comparison of CD40 agonist formats reveals superior immune-modulating properties of hexavalent scCD40L-RBD-Fc fusion protein APG1233. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B48.

hvTRA, a novel TRAIL receptor agonist, induces apoptosis and sustained growth retardation in melanoma

In recent years, new treatment options for malignant melanoma patients have enhanced the overall survival for selected patients. Despite new hope, most melanoma patients still relapse with drug-resistant tumors or experience intrinsic resistance to the therapy. Therefore, novel treatment modalities beneficial for subgroups of patients are needed. TRAIL receptor agonists have been suggested as promising candidates for use in cancer treatment as they preferentially induce apoptosis in cancer cells. Unfortunately, the first generation of TRAIL receptor agonists showed poor clinical efficacy. hvTRA is a second-generation TRAIL receptor agonist with improved composition giving increased potency, and in the present study, we showed hvTRA-induced activation of apoptosis leading to an efficient and sustained reduction in melanoma cell growth in cell lines and xenograft models. Furthermore, the potential of hvTRA in a clinical setting was demonstrated by showing efficacy on tumor cells harvested from melanoma patients with lymph node metastasis in an ex vivo drug sensitivity assay. Inhibition of mutated BRAF has been shown to regulate proteins in the intrinsic apoptotic pathway, making the cells more susceptible for apoptosis induction. In an attempt to increase the efficacy of hvTRA, combination treatment with the mutated BRAF inhibitor vemurafenib was investigated. A synergistic effect by the combination was observed for several cell lines in vitro, and an initial cytotoxic effect was observed in vivo. Unfortunately, the initial increased reduction in tumor growth compared with hvTRA mono treatment was not sustained, and this was related to downregulation of the DR5 level by vemurafenib. Altogether, the presented data imply that hvTRA efficiently induce apoptosis and growth delay in melanoma models and patient material, and the potential of this TRAIL receptor agonist should be further evaluated for treatment of subgroups of melanoma patients.

Abstract B066: The hexavalent CD40 agonist APG1233 is a superior inducer of immune cell activation compared to trimeric formats or agonistic anti-CD40 antibodies

Introduction: The co-stimulatory receptor CD40 is strongly expressed on B cells, monocytes and antigen-presenting cells (APC). By promoting their maturation, activation and survival, CD40 signaling greatly contributes to anti-tumor responses of the immune system. The HERA-Technology developed by Apogenix is a powerful engineering platform for the production of modular fusion proteins targeting the TNF-receptor superfamily. Structurally, these novel ligands comprise a single-chain arrangement of three TNFSF protomers forming one TNFSF-receptor binding domain (RBD) with specific linkers and the Fc-part of human IgG as dimerization scaffold. The result is a stable and defined hexavalent receptor agonist with high clustering capacity for the cognate receptor. Here we compared the efficacy of different CD40 agonist formats, including the novel hexavalent scCD40L-RBD-Fc (APG1233), and the functional consequences of differential receptor clustering. In addition, the in vivo pharmacokinetics of the fully human APG1233 is compared with a chimeric mouse/human surrogate molecule APG1274.

Materials and Methods: Immune cells were isolated from healthy-donor blood samples and profiled by multicolor flow cytometry (MC-FC). Subsequently, immune cells were cultured in growth media containing various forms of CD40 agonists. Upregulation of activation markers on B cells and monocytes (e.g. CD69, CD86, HLA-DR) and T cell-induced killing of tumor cells in direct co-culture was assessed by MC-FC and employing a real-time cell analysis system (xCELLigence), respectively. Secretion of cytokines in response to CD40 ligation and the pharmacokinetic properties of the fully human APG1233 and the chimeric murine/human APG1274 were determined by ELISA.

Results: In vivo stability of APG1233 was demonstrated in a single dose mouse PK study revealing a terminal half-life of 84 hours. The human CD40L, however, does not bind murine CD40. Therefore, we used APG1274, a chimeric protein comprising the murine CD40L fused to human IgG and binding to mouse CD40, to determine serum pharmacokinetics. As a result of functional binding of APG1274 to murine CD40, the surrogate molecule is eliminated much quicker (t1/2 of 4 hours) demonstrating the specificity of both compounds. In vitro only the hexavalent APG1233 displayed activity in terms of stimulation of B cells, monocytes and PBMCs. In contrast, neither trimeric CD40L nor an agonistic antibody against CD40 were able to upregulate expression of activation markers. Similarly, the secretion of proinflammatory cytokines such as IL-12, CD95L and IFNγ by PBMCs was only stimulated after exposure to APG1233 and not in the presence of other CD40 agonists. In functional co-culture assays, after exposure to APG1233, in vitro generated M2-macrophages underwent conversion and acquired M1-type surface markers which strongly enhanced proliferation of naïve CD4+ T cells. Induction by M2-macrophages in this setup was much lower. Consistent with these data, only the hexavalent CD40 agonist APG1233 efficiently increased direct cytotoxic activity of immune cells against tumor cells measured by a real-time cell analysis assay.

Conclusion: The CD40 agonist APG1233 is a member of a novel class of hexavalent TNFRSF agonists which binds its target with high specificity, exhibits excellent in vivo stability and superior biological activity over other agonistic formats (e.g. agonistic antibodies).

Citation Format: Christian Merz, Jaromir Sykora, Meinolf Thiemann, David M. Richards, Thamara Beyer, Stefanie Kühn, Harald Fricke, Christian Gieffers, Oliver Hill. The hexavalent CD40 agonist APG1233 is a superior inducer of immune cell activation compared to trimeric formats or agonistic anti-CD40 antibodies [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B066.

Peripheral monocytes are functionally altered and invade the CNS in ALS patients

Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disease affecting primarily the upper and lower motor neurons. A common feature of all ALS cases is a well-characterized neuroinflammatory reaction within the central nervous system (CNS). However, much less is known about the role of the peripheral immune system and its interplay with CNS resident immune cells in motor neuron degeneration. Here, we characterized peripheral monocytes in both temporal and spatial dimensions of ALS pathogenesis. We found the circulating monocytes to be deregulated in ALS regarding subtype constitution, function and gene expression. Moreover, we show that CNS infiltration of peripheral monocytes correlates with improved motor neuron survival in a genetic ALS mouse model. Furthermore, application of human immunoglobulins or fusion proteins containing only the human Fc, but not the Fab antibody fragment, increased CNS invasion of peripheral monocytes and delayed the disease onset. Our results underline the importance of peripheral monocytes in ALS pathogenesis and are in agreement with a protective role of monocytes in the early phase of the disease. The possibility to boost this beneficial function of peripheral monocytes by application of human immunoglobulins should be evaluated in clinical trials.

Abstract 1204: A construction platform for hexavalent agonists targeting receptors of the tumor necrosis factor superfamily: Where death meets co-stimulation

Tumor necrosis factor receptor superfamily (TNFRSF) proteins are widely expressed by immune and tumor cells. Their importance in many locations and phases of the anti-tumor immune response is now broadly appreciated and several TNFR agonists are currently in preclinical and clinical development. Importantly, signaling through many TNFRSF members, such as CD40, CD27, OX40, 4-1BB, HVEM and GITR, is potentially associated with an enhanced anti tumor response via co-stimulation of immune cells.

Apogenix has established a development platform for a novel class of TNFRSF-agonists for the treatment of cancer. Unlike their natural homotrimeric counterparts, the Apogenix recombinant TNFSF proteins consist of one single polypeptide chain composed of three receptor-binding domain-forming protomers. These single-chain TNFSF receptor-binding domains (scTNFSF-RBD) are mimics of the three-dimensional organization of the natural TNFSF-cytokine and can be used to engineer fully human fusion-proteins from a modular toolbox. For example, fusing an IgG1 Fc-domain to the C-terminus of a scTNFSF-RBD creates a hexavalent agonist as the Fc-domain acts as a dimerization scaffold for two trivalent scTNFSF-RBDs. As a result of this molecular design, each drug molecule is capable of clustering six receptors in a spatially well-defined manner. Consequently, TNFSF receptor signaling following treatment with the Apogenix scTNFSF-RBD-Fc in vivo is independent of secondary clustering through Fc-γ receptors that is required for many anti-TNFRSF agonistic antibodies (e.g., anti-TRAILR2 or -CD40).

Following up the scTRAIL-RBD-Fc prototype, this engineering concept has now been successfully translated to CD40L and CD27L resulting in hexavalent agonists suitable for further development. Expression of the drug candidates in CHO suspension cells followed by an AFC and SEC-based lab-scale purification process resulted in homogenous aggregate-free protein lots. The purified proteins bind their respective target-receptors with high affinity. In vivo stability/PK studies have been performed in addition to in vitro experiments with primary human and mouse lymphoid and myeloid cell populations. Specifically, it was shown that scCD27L-RBD-Fc was able to bind CD27 expressed on primary human CD4+ and CD8+ T cells. Importantly, binding significantly increased T cell expansion following activation. Treatment with scCD40L-RBD-Fc induced differentiation of B cells and enhanced primary human monocyte differentiation into DCs or M1 macrophages.

Encouraged by the promising results obtained with TRAIL, CD40L, and CD27L, Apogenix is currently expanding the TNFRSF-agonist pipeline to target additional cell populations, locations and phases of the immune response in order to develop novel therapies to treat cancer and other conditions.

Citation Format: Christian Merz, Christian Gieffers, Michael Kluge, David M. Richards, Tim Schnyder, Jaromir Sykora, Meinolf Thiemann, Harald Fricke, Oliver Hill. A construction platform for hexavalent agonists targeting receptors of the tumor necrosis factor superfamily: Where death meets co-stimulation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1204.

Infiltration of circulating myeloid cells through CD95L contributes to neurodegeneration in mice

Gao et al. report that genetic or pharmacological blockade of CD95 ligand prevents infiltration of peripheral myeloid cells and thereby averts toxin-induced neurodegeneration in mice.

Neuroinflammation is increasingly recognized as a hallmark of neurodegeneration. Activated central nervous system–resident microglia and infiltrating immune cells contribute to the degeneration of dopaminergic neurons (DNs). However, how the inflammatory process leads to neuron loss and whether blocking this response would be beneficial to disease progression remains largely unknown. CD95 is a mediator of inflammation that has also been proposed as an apoptosis inducer in DNs, but previous studies using ubiquitous deletion of CD95 or CD95L in mouse models of neurodegeneration have generated conflicting results. Here we examine the role of CD95 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP)–induced neurodegeneration using tissue-specific deletion of CD95 or CD95L. We show that DN death is not mediated by CD95-induced apoptosis because deletion of CD95 in DNs does not influence MPTP-induced neurodegeneration. In contrast, deletion of CD95L in peripheral myeloid cells significantly protects against MPTP neurotoxicity and preserves striatal dopamine levels. Systemic pharmacological inhibition of CD95L dampens the peripheral innate response, reduces the accumulation of infiltrating myeloid cells, and efficiently prevents MPTP-induced DN death. Altogether, this study emphasizes the role of the peripheral innate immune response in neurodegeneration and identifies CD95 as potential pharmacological target for neurodegenerative disease.

CD95 promotes metastatic spread via Sck in pancreatic ductal adenocarcinoma

Cancer stem cells (CSCs) have been implicated in the initiation and maintenance of tumour growth as well as metastasis. Recent reports link stemness to epithelial–mesenchymal transition (EMT) in cancer. However, there is still little knowledge about the molecular markers of those events. In silico analysis of RNA profiles of 36 pancreatic ductal adenocarcinomas (PDAC) reveals an association of the expression of CD95 with EMT and stemness that was validated in CSCs isolated from PDAC surgical specimens. CD95 expression was also higher in metastatic pancreatic cells than in primary PDAC. Pharmacological inhibition of CD95 activity reduced PDAC growth and metastasis in CSC-derived xenografts and in a murine syngeneic model. On the mechanistic level, Sck was identified as a novel molecule indispensable for CD95's induction of cell cycle progression. This study uncovers CD95 as a marker of EMT and stemness in PDAC. It also addresses the molecular mechanism by which CD95 drives tumour growth and opens tantalizing therapeutic possibilities in PDAC.

Abstract 4986: APG101 inhibits CD95-Ligand induced invasion of glioblastoma in 3D-models in vitro and ex vivo

CD95 (APO-1/Fas) is a receptor that belongs to the Tumor Necrosis Factor Receptor Super Family (TNFRSF). Originally discovered as a death receptor inducing apoptosis upon binding to its ligand CD178 (CD95L/FasL), recent research indicates that CD95 also mediates non-apoptotic functions (e.g. liver regeneration, neuronal development, inflammation and cellular migration/invasion of tumor cells) depending on the cellular context. The potential impact on multiple cellular processes classifies the CD95 pathway as an attractive target for pharmacological interference. Apogenix developed APG101, a recombinant human fusion protein consisting of the extracellular domain of CD95 and the Fc-domain of an IgG antibody for the treatment of glioblastoma, a malignancy characterized by aggressive and invasive growth. Preclinical development activities to elucidate the mode of action of APG101 included the comparison of 3-dimensional in vitro and ex vivo models employing U87-MG and U373-MG cells on murine organotypic brain tissue cultures. Expression of CD95L and CD95 in these cells was reduced by semi-stable transfection of shRNA vectors to assess contribution of the CD95/CD95L system to invasion and proliferation of glioma cell lines and the anti-invasive effect of APG101 treatment. While knockdown of CD95 leads to death of U373-MG cells, we observed significant reduction of proliferation rates in U87-MG cells. The effect of CD95L knockdown on proliferation was only minor in U87-MG and was absent in U373-MG cells. Consistently, we found that treatment of glioma cells with APG101 had no effect on proliferation rates or cell cycle regulation of either cell line. The main effect of CD95L knockdown was a strongly reduced invasiveness of both cell lines in vitro and ex vivo. Invasiveness could be restored by exogenous addition of recombinant CD95L, and this induced invasion was inhibited in the presence of APG101. In contrast, a CD95L binding defective CD95-Fc mutant APG122 did not have an anti-invasive effect in our experimental models. We conclude that: Results obtained from the in vitro and ex vivo assay models reflect each other and are suitable to study the role of CD95 signaling in tumor cell invasion activation of CD95 on glioma cells by CD95L contributes to invasive spread of tumor cells to the surrounding brain tissue, and Apogenix drug APG101 is able to block the pro-invasive activity of CD95L. Based on these observations, an important mode of action for APG101 is inhibition of CD95 ligand induced invasion of glioma cells.

Citation Format: Christian Merz, Alexander Strecker, Jaromir Sykora, Oliver Hill, Gieffers Christian, Harald Fricke, Peter Angel, Heike Peterziel. APG101 inhibits CD95-Ligand induced invasion of glioblastoma in 3D-models in vitro and ex vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4986. doi:10.1158/1538-7445.AM2014-4986

APG350 induces superior clustering of TRAIL receptors and shows therapeutic antitumor efficacy independent of cross-linking via Fcγ receptors

Cancer cells can be specifically driven into apoptosis by activating Death-receptor-4 (DR4; TRAIL-R1) and/or Death-receptor-5 (DR5; TRAIL-R2). Albeit showing promising preclinical efficacy, first-generation protein therapeutics addressing this pathway, especially agonistic anti-DR4/DR5-monoclonal antibodies, have not been clinically successful to date. Due to their bivalent binding mode, effective apoptosis induction by agonistic TRAIL-R antibodies is achieved only upon additional events leading to antibody-multimer formation. The binding of these multimers to their target subsequently leads to effective receptor-clustering on cancer cells. The research results presented here report on a new class of TRAIL-receptor agonists overcoming this intrinsic limitation observed for antibodies in general. The main feature of these agonists is a TRAIL-mimic consisting of three TRAIL-protomer subsequences combined in one polypeptide chain, termed the single-chain TRAIL-receptor-binding domain (scTRAIL-RBD). In the active compounds, two scTRAIL-RBDs with three receptor binding sites each are brought molecularly in close proximity resulting in a fusion protein with a hexavalent binding mode. In the case of APG350-the prototype of this engineering concept-this is achieved by fusing the Fc-part of a human immunoglobulin G1 (IgG1)-mutein C-terminally to the scTRAIL-RBD polypeptide, thereby creating six receptor binding sites per drug molecule. In vitro, APG350 is a potent inducer of apoptosis on human tumor cell lines and primary tumor cells. In vivo, treatment of mice bearing Colo205-xenograft tumors with APG350 showed a dose-dependent antitumor efficacy. By dedicated muteins, we confirmed that the observed in vivo efficacy of the hexavalent scTRAIL-RBD fusion proteins is-in contrast to agonistic antibodies-independent of FcγR-based cross-linking events.

Abstract 3856: Dimerized single chain TRAIL-receptor agonists do not depend on Fc-gamma-receptor cross-linking for anti-tumor efficacy in vivo

APG350 is a TRAIL-receptor (TRAIL-R) agonist comprising two single-chain TRAIL-R binding domains (scTRAIL-RBD) that are dimerized via the Fc-part of a human IgG1-mutein thereby creating six receptor binding sites per molecule. This improved ability to form clusters on target cells composed of six TRAIL-Rs each, distinguishes APG350 from current clinical development candidates. In vitro, comparison of APG350 with recombinant APO2L/TRAIL and a TRAIL-R2 specific agonistic antibody revealed superior apoptosis induction for APG350 on primary and established human tumor cell-lines. Treatment of mice bearing Colo205 xenograft tumors with APG350, APO2L/TRAIL or an agonistic TRAIL-R2 specific antibody showed superior anti-tumor efficacy for APG350. Pronounced anti tumor efficacy was also shown on colon cancer stem cell (CSC) derived xenografts and successful APG350 re-treatment of relapsed CSC derived tumors demonstrated that tumors did not develop drug resistance. For most agonistic TRAIL-R antibodies effective apoptosis induction is achieved only upon additional cross-linking. SEC-based fractionation of a TRAIL-R2 specific agonistic antibody indicates a small amount of multimerized antibody that showed efficient apoptosis induction in vitro. However, the respective monomeric antibody showed poor apoptosis induction in vitro that could be enhanced upon cross-linking. In contrast apoptosis induction by APG350 was only marginally enhanced by cross-linking. Although monomeric agonistic TRAIL-R antibodies are poor apoptosis inducers in vitro, they show efficient apoptosis induction on xenograft tumors in vivo. A likely explanation for this difference is given by a recent publication showing that anti-tumor efficacy of an agonistic TRAIL-R2 specific antibody (Drozitumab) depends on cross-linking by Fcα-receptors (FcαR) in vivo. These data suggest that FcαR cross-linking might be a common requirement for the anti-tumor efficacy of agonistic TRAIL-R antibodies. To exclude that in vivo efficacy of APG350 depends on cross-linking by FcαRs we designed APG350-muteins with strongly reduced (APG808) or lacking FcαR binding (APG780). Side by side comparison of APG808, APG780 and APG350 in mice bearing Colo205-derived xenograft tumors showed identical anti-tumor efficacy for all respective proteins. Given that APG780 cannot bind to FcαRs these results suggest that the anti-tumor efficacy of APG808, APG780 and APG350 is solely based on the unique construction principle of the dimerized scTRAIL-RBD. APG350 induces superior clustering of TRAIL-Rs that in contrast to agonistic TRAIL-R antibodies does not require cross-linking via FcαRs for its potent anti-tumor efficacy. APG350 based dimerized scTRAIL-RBD formats may therefore have the capacity to bridge the current gap seen between preclinical and clinical efficacy for agonistic TRAIL-R specific antibodies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3856. doi:1538-7445.AM2012-3856

Abstract LB-232: APG350, a dimerized single chain TRAIL receptor agonist with enhanced functional properties

TRAIL (Apo2L) is a member of the Tumor Necrosis Factor Superfamily (TNF-SF) that induces apoptosis through binding to two closely related receptors, TRAIL-R1 and TRAIL-R2. Its unique ability of selective apoptosis induction in tumor cells makes TRAIL an attractive molecule for tumor therapy.

APG350 is a newly designed TRAIL-receptor agonist comprising two single-chain TRAIL-receptor binding domains (each consisting of three covalently linked TRAIL protomers) that are dimerized via the Fc-part of human IgG1. APG350 has six receptor binding sites per molecule and binds to both death inducing TRAIL receptors. In vitro, APG350 shows potent apoptosis induction on a wide subset of human tumor cell-lines, on cancer stem cells and on primary tumor cells. Mechanistically its improved ability to form clusters on target cells composed of six TRAIL-receptors each, distinguishes APG350 from current clinical development candidates. Agonistic antibodies like Conatumumab or Apomab are capable to bind two receptor chains per molecule, while recombinant TRAIL (e.g. Dulanermin) binds three receptor chains per molecule. Direct in vitro comparison of APG350 with recombinant TRAIL (APG400) and a TRAIL-R2 specific agonistic monoclonal antibody revealed superior apoptosis induction capacity for APG350.

Analysis of the PK-parameters in mice showed a half life of 23.1h for APG350 (1.04h for APG400) indicating a significantly improved PK in comparison to APG400. The half life of APG350 in a Cynomolgus monkey was 26.7h.

Comparative treatment of mice bearing Colo205 xenograft tumors with APG350 and APG400 employing one treatment cycle with five consecutive daily intravenous injections showed a superior efficacy of APG350 with respect to tumor volume reduction and number of tumor free animals. Even mice with initially large tumors (∼600 mm3) were treated effectively with APG350. Remarkably, APG350 also showed pronounced dose dependent anti tumor efficacy on xenograft-tumors derived from colon cancer stem cells (CSC). Furthermore large CSC-derived tumors could be treated effectively and successful re-treatment of previously responding tumors demonstrated that tumors did not gain drug resistance. In a pilot experiment APG350 treatment of mice bearing a slowly growing primary rectum tumor xenograft also showed a significant tumor volume reduction. In all in vivo studies APG350 was well tolerated at doses between 0.3–100mg/kg bw in mice and doses up to 10mg/kg bw in a Cynomolgus monkey. General tolerability and potential effects on liver toxicity were assessed by co-application of APG350 together with a crosslinking antibody in mice. This treatment evoked only minor clinical signs at high doses with no relevant increase in liver enzymes. Currently two non-GLP toxicology studies, a 4-week study in mice and a dose escalation study in Cynomolgus monkeys are ongoing to confirm tolerability in vivo.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-232. doi:10.1158/1538-7445.AM2011-LB-232

CD95-ligand on peripheral myeloid cells activates Syk kinase to trigger their recruitment to the inflammatory site

Injury to the central nervous system initiates an uncontrolled inflammatory response that results in both tissue repair and destruction. Here, we showed that, in rodents and humans, injury to the spinal cord triggered surface expression of CD95 ligand (CD95L, FasL) on peripheral blood myeloid cells. CD95L stimulation of CD95 on these cells activated phosphoinositide 3-kinase (PI3K) and metalloproteinase-9 (MMP-9) via recruitment and activation of Syk kinase, ultimately leading to increased migration. Exclusive CD95L deletion in myeloid cells greatly decreased the number of neutrophils and macrophages infiltrating the injured spinal cord or the inflamed peritoneum after thioglycollate injection. Importantly, deletion of myeloid CD95L, but not of CD95 on neural cells, led to functional recovery of spinal injured animals. Our results indicate that CD95L acts on peripheral myeloid cells to induce tissue damage. Thus, neutralization of CD95L should be considered as a means to create a controlled beneficial inflammatory response.

The design of potent and selective inhibitors of DPP-4: optimization of ADME properties by amide replacements

For a series of beta-homophenylalanine based inhibitors of dipeptidyl peptidase IV ADME properties were improved by the incorporation of amide replacements. These efforts led to a novel series of potent and selective inhibitors of DPP-4 that exhibit an attractive pharmacokinetic profile and show excellent efficacy in an animal model of diabetes.

Discovery of beta-homophenylalanine based pyrrolidin-2-ylmethyl amides and sulfonamides as highly potent and selective inhibitors of dipeptidyl peptidase IV

Modifications of DPP-4 inhibitor 5, that was discovered by structure based design, are described and structure-activity relationships discussed. With analogue 7k one of the most potent non-covalent inhibitors of DPP-4 reported to date (IC(50)=0.38nM) was discovered. X-ray structure of inhibitor 7k bound to DPP-4 revealed a hydrogen bonding interaction with Q553. First successful efforts in balancing overall properties, as demonstrated by improved metabolic stability, highlight the potential of this series.

Yes and PI3K bind CD95 to signal invasion of glioblastoma

Invasion of surrounding brain tissue by isolated tumor cells represents one of the main obstacles to a curative therapy of glioblastoma multiforme. Here we unravel a mechanism regulating glioma infiltration. Tumor interaction with the surrounding brain tissue induces CD95 Ligand expression. Binding of CD95 Ligand to CD95 on glioblastoma cells recruits the Src family member Yes and the p85 subunit of phosphatidylinositol 3-kinase to CD95, which signal invasion via the glycogen synthase kinase 3-beta pathway and subsequent expression of matrix metalloproteinases. In a murine syngeneic model of intracranial GBM, neutralization of CD95 activity dramatically reduced the number of invading cells. Our results uncover CD95 as an activator of PI3K and, most importantly, as a crucial trigger of basal invasion of glioblastoma in vivo.

The reversed binding of β-phenethylamine inhibitors of DPP-IV: X-ray structures and properties of novel fragment and elaborated inhibitors

The co-crystal structure of beta-phenethylamine fragment inhibitor 5 bound to DPP-IV revealed that the phenyl ring occupied the proline pocket of the enzyme. This finding provided the basis for a general hypothesis of a reverse binding mode for beta-phenethylamine-based DPP-IV inhibitors. Novel inhibitor design concepts that obviate substrate-like structure-activity relationships (SAR) were thereby enabled, and novel, potent inhibitors were discovered.

Design of helical proteins for real-time endoprotease assays

Proteases play a key role in cellular biology and have become priority targets for new pharmaceuticals. Thus, there is a high demand for specific, sensitive, and quick assays to monitor the activity of endoproteases. We designed affinity-tagged helical proteins with unique protease cleavage sites and thus constructed universal, molecularly defined, and uniform substrates for in vitro detection of IgA endoprotease. The substrate is a 10.5-kDa recombinant helical protein with a high-affinity (His)(6)-tag at the amino-terminal end. Further elements are a unique proteolytic recognition site and a C-terminal helical extension, which is cut off by the protease. Proteolytic action can be monitored in real time using surface plasmon resonance spectroscopy. Femtomole amounts of protease could be reliably and quantitatively detected within a few minutes after the start of the reaction. The detection signal changed linearly with the amount of protease and was independent of the applied sample flow rate. The biochip can be reversibly loaded with the recombinant protease substrate, so that the SPR assay is well-suited for automation. By substituting an HIV protease site for the recognition site of the IgAse, we also obtained a substrate for the quantitative and sensitive detection of HIV-1 endoprotease. Our substrate design is thus generally applicable.

Violence, homicide and suicide: strong correlation and wide variation across districts

BACKGROUND

The clinical assessment and management of the risk of violence and suicide by people with mental illness may have to focus on environmental as well as individual factors.

AIMS

To investigate possible associations between violence, homicide and suicide rates, population density and indices of deprivation, with particular reference to inner-city boroughs.

METHOD

Coroners' statistics in London for homicide and suicide were obtained, with police-reported homicide and violence rates as a validity check. Correlations were made between these data and population density, the Jarman under-privileged areas score, and the Mental Illness Needs Index for each of the 32 London boroughs.

RESULTS

Homicide rates had a 14.3-fold range, suicide a 4.4-fold range and interpersonal violence a 6.6-fold range. The variables under study were strongly correlated with each other. Rates were highest in boroughs with high population density and deprivation scores. The associations persisted when covarying for deprivation, age structure or population density.

CONCLUSIONS

Because violence, homicide and suicide are so closely correlated, they are likely to be valid indices of the differences between adjacent boroughs; this has implications for the delivery of preventive and mental health services and for clinical management of risk.

Porcine guanylin and uroguanylin: cDNA sequences, deduced amino acid sequences, and biological activity of the chemically synthesized peptides

Guanylin and uroguanylin are structurally related intestinal peptide hormones which were purified from a limited number of mammals and are capable of activating the particulate guanylate cyclase-C. Although the biological functions of guanylin and uroguanylin are not yet clarified in detail, they are involved in the regulation of the intestinal water and electrolyte balance. In order to verify the general importance of this hormone system in mammals, we cloned the corresponding cDNAs from pig. Here, we present the nucleotide sequences and the deduced amino acid sequences representing porcine guanylin and uroguanylin. The expression patterns of the corresponding genes, as shown by Northern hybridization and RT-PCR analysis, resemble those of the human homologues. Further, we demonstrate the bioactivity of both porcine peptide hormones by inducing the intracellular cGMP production in human T84 cells and by ion transport experiments using porcine intestinal mucosa in the Ussing chamber.