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Luus L, Hurov K, Lahdenranta J, Shah C, Devlen A, Kristensson J, Brown P, Bray C, Cohen H, Campbell C, Mudd G, Upadhyaya P, McDonnell K, Xu H, Jeffrey P, Brandish PE, Keen N. Abstract 1832: EphA2-dependent CD137 agonism and anti-tumor efficacy by BT7455, a Bicycle tumor-targeted immune cell agonist®. Cancer Res 2023. [DOI: 10.1158/1538-7445.am2023-1832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Abstract
We have developed a new class of modular synthetic drugs, termed Bicycle® tumor-targeted immune cell agonists (Bicycle® TICAs), which are multi-specific molecules composed of constrained bicyclic peptides (Bicycles)1. The first molecule of this class, BT7480, a Nectin-4-dependent CD137 (4-1BB) agonist, entered clinical trials in 2021 in patients with solid tumors associated with Nectin-4 expression. Compelling preclinical data characterizing BT74802 led us to develop a second Bicycle TICA® molecule, BT7455, which is designed to deliver highly potent CD137 agonism to Ephrin receptor A2 (EphA2)-positive cancers. EphA2 is a receptor tyrosine kinase overexpressed in several human cancers and high expression correlates with poor clinical prognosis in certain cancer types3,4. BT7455 pharmacology was assessed in vitro using surface plasmon resonance, receptor occupancy assays, and PBMC/tumor cell co-culture bioactivity assays. BT7455 in vivo activity was evaluated in efficacy studies in syngeneic EphA2-positive mouse tumor models and pharmacodynamic studies using transcriptional profiling of the tumor immune microenvironment. BT7455 engages EphA2 and CD137 with high affinity resulting in potent EphA2-dependent production of interleukin-2 (IL-2) and interferon gamma (IFNγ) in human PBMC/tumor cell co-culture assays. Treatment of MC38 tumor bearing immunocompetent mice with BT7455 using an intermittent dosing regimen led to robust anti-tumor activity, including complete responses. Gene expression profiling of BT7455-treated tumors revealed modulation of the tumor immune microenvironment, including a rapid increase in cytokine expression (both myeloid and T cell origin) and an increase in cytotoxic cell scores. The kinetics and extent of the immune microenvironment modulation differentiated BT7455 from both a checkpoint inhibitor (anti-mouse PD-1) as well as an anti-CD137 agonist antibody (urelumab analogue). To pinpoint the cells responsible for the early bursts of cytokine and chemokine gene expression, we depleted CD8-positive T cells from the mice prior to CD137 Bicycle TICA® treatment. We found that the early increase in gene expression of distinct chemokines was not dependent on CD8-positive T cells. We have now turned to single-cell RNA sequencing of CD137 Bicycle TICA®-treated tumors to further probe the mechanistic underpinning of this novel finding. In summary, BT7455 is a highly potent EphA2-dependent CD137 agonist with optimal target binding, pharmacologic, and pharmacokinetic properties that enable intermittent dosing for curative effect through modulation of the tumor immune microenvironment in syngeneic mouse models. BT7455 is currently being evaluated in IND-enabling studies. 1Upadhyaya P, et al. JITC 2021; 9:e001762. 2Hurov K, et al. JITC 2021; 9:e002883. 3Campbell C, et al. Cancer Res 2020; 80:5300 4Xiao, et al. J Hematol Oncol 2020; 13:114.
Citation Format: Lia Luus, Kristen Hurov, Johanna Lahdenranta, Chinmayee Shah, Anna Devlen, Julia Kristensson, Peter Brown, Cara Bray, Heather Cohen, Carly Campbell, Gemma Mudd, Punit Upadhyaya, Kevin McDonnell, Hongmei Xu, Phil Jeffrey, Philip E. Brandish, Nicholas Keen. EphA2-dependent CD137 agonism and anti-tumor efficacy by BT7455, a Bicycle tumor-targeted immune cell agonist® [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1832.
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Rigby M, Bennett G, Chen L, Mudd GE, Harrison H, Beswick PJ, Van Rietschoten K, Watcham SM, Scott HS, Brown AN, Park PU, Campbell C, Haines E, Lahdenranta J, Skynner MJ, Jeffrey P, Keen N, Lee K. BT8009; A Nectin-4 Targeting Bicycle Toxin Conjugate for Treatment of Solid Tumors. Mol Cancer Ther 2022; 21:1747-1756. [PMID: 36112771 PMCID: PMC9940631 DOI: 10.1158/1535-7163.mct-21-0875] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 07/01/2022] [Accepted: 09/09/2022] [Indexed: 01/12/2023]
Abstract
Multiple tumor types overexpress Nectin-4 and the antibody-drug conjugate (ADC), enfortumab vedotin (EV) shows striking efficacy in clinical trials for metastatic urothelial cancer, which expresses high levels of Nectin-4, validating Nectin-4 as a clinical target for toxin delivery in this indication. Despite excellent data in urothelial cancer, little efficacy data are reported for EV in other Nectin-4 expressing tumors and EV therapy can produce significant toxicities in many patients, frequently leading to discontinuation of treatment. Thus, additional approaches to this target with the potential to extend utility and reduce toxicity are warranted. We describe the preclinical development of BT8009, a "Bicycle Toxin Conjugate" (BTC) consisting of a Nectin-4-binding bicyclic peptide, a cleavable linker system and the cell penetrant toxin mono-methylauristatin E (MMAE). BT8009 shows significant antitumor activity in preclinical tumor models, across a variety of cancer indications and is well tolerated in preclinical safety studies. In several models, it shows superior or equivalent antitumor activity to an EV analog. As a small hydrophilic peptide-based drug BT8009 rapidly diffuses from the systemic circulation, through tissues to penetrate the tumor and target tumor cells. It is renally eliminated from the circulation, with a half-life of 1-2 hours in rat and non-human primate. These physical and PK characteristics differentiate BT8009 from ADCs and may provide benefit in terms of tumor penetration and reduced systemic exposure. BT8009 is currently in a Phase 1/2 multicenter clinical trial across the US, Canada, and Europe, enrolling patients with advanced solid tumors associated with Nectin-4 expression.
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Cohen H, Bray C, Kanakia D, Lahdenranta J, Upadhyaya P, Hurov K, Kristensson J, Jobaliya C, Bannish G, Cotty A, McDonnell K, Hirschberg S, Hazard S, Smethurst D, Keen N, Blakemore SJ. Abstract A65: Development of a CD137 receptor occupancy assay to support the Phase I/II study of BT7480, a Bicycle® tumor-targeted immune cell agonist ® (Bicycle TICA™). Cancer Immunol Res 2022. [DOI: 10.1158/2326-6074.tumimm22-a65] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Abstract
Bicycles are fully synthetic constrained peptides with antibody-like affinities that target selectively, readily penetrate tumor tissue, have relatively short half-lives, and can be chemically linked together to generate multifunctional molecules. BT7480 is a Bicycle TICA™ being developed as a first-in-class CD137 therapeutic for the treatment of human cancers associated with Nectin-4 expression and is currently being investigated in an ongoing Phase I/II clinical trial. Monitoring target engagement for a given therapeutic can be a key factor in recommending the Phase II dose. While flow cytometry-based receptor occupancy (RO) assays are commonly used to monitor target engagement in the clinic, a CD137-specific RO assay presents several important challenges that have historically hampered monitoring RO in the clinic including the dynamic expression of CD137 on unstimulated and stimulated T cells, the low frequency of CD137+ cells in human blood and limited reagents to confidently detect CD137+ cells in the presence of CD137-targeting drugs. To address these challenges, a fit-for-purpose 14-plex flow cytometry panel was developed that incorporates a fluorescently labelled CD137-specific binding Bicycle®. This Bicycle® was shown to directly compete with a Bicycle TICA™ for binding to CD137, but not with a fluorescently labelled anti-CD137 antibody, thereby enabling simultaneous detection of various CD137+ immune cell types as well as receptor occupancy by BT7480 in a single blood sample. Panel performance was tested across blood-based sample matrices routinely used in the clinic including EDTA and Cyto-Chex® blood collection tubes and Cell Preparation Tubes (CPT) (n=3 each). CPT were selected as the optimal sample matrix based on sample viability and highest detection of CD137 antibody+ and CD137 Bicycle®+ cells. Ex vivo RO assessments in anti-CD3 stimulated and unstimulated healthy human blood demonstrated dose-dependent detection of BT7480-occupied CD137, as well as the detection of >1000 CD137+ cells with sample viability >70% (n=5 each). The optimized method and dose-dependent detection of CD137+ cells and BT7480-occupied CD137 were further verified in unstimulated lung cancer patient whole blood samples (n≥5). Results from this study represent the first report of a clinic-ready CD137 RO assay and the first flow cytometry assay using fluorescently labelled Bicycle® reagents and demonstrate the utility of the Bicycle® CD137 RO assay to monitor target engagement in the BT7480 first-in-human clinical trial.
Citation Format: Heather Cohen, Cara Bray, Drasti Kanakia, Johanna Lahdenranta, Punit Upadhyaya, Kristen Hurov, Julia Kristensson, Chintan Jobaliya, Greg Bannish, Adam Cotty, Kevin McDonnell, Sandra Hirschberg, Sebastien Hazard, Dominic Smethurst, Nicholas Keen, Stephen J Blakemore. Development of a CD137 receptor occupancy assay to support the Phase I/II study of BT7480, a Bicycle® tumor-targeted immune cell agonist ® (Bicycle TICA™) [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr A65.
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Upadhyaya P, Kristensson J, Lahdenranta J, Repash E, Ma J, Kublin J, Mudd GE, Luus L, Jeffrey P, Hurov K, McDonnell K, Keen N. Discovery and Optimization of a Synthetic Class of Nectin-4-Targeted CD137 Agonists for Immuno-oncology. J Med Chem 2022; 65:9858-9872. [PMID: 35819182 PMCID: PMC9340768 DOI: 10.1021/acs.jmedchem.2c00505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
![]()
CD137 (4-1BB) is a co-stimulatory receptor on immune
cells and
Nectin-4 is a cell adhesion molecule that is overexpressed in multiple
tumor types. Using a series of poly(ethylene glycol) (PEG)-based linkers,
synthetic bicyclic peptides targeting CD137 were conjugated to Bicycles targeting Nectin-4. The resulting bispecific molecules
were potent CD137 agonists that require the presence of both Nectin-4-expressing
tumor cells and CD137-expressing immune cells for activity. A multipronged
approach was taken to optimize these Bicycle tumor-targeted
immune cell agonists by exploring the impact of chemical configuration,
binding affinity, and pharmacokinetics on CD137 agonism and antitumor
activity. This effort resulted in the discovery of BT7480, which elicited
robust CD137 agonism and maximum antitumor activity in syngeneic mouse
models. A tumor-targeted approach to CD137 agonism using low-molecular-weight,
short-acting molecules with high tumor penetration is a yet unexplored
path in the clinic, where emerging data suggest that persistent target
engagement, characteristic of biologics, may lead to suboptimal immune
response.
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Dufort FJ, Leitheiser CJ, Mudd G, Kristensson J, Rezvaya A, Gaynor K, Uhlenbroich S, Urbonas L, Scott H, Chen L, Harrison H, Skynner M, McDonnell K, Brandish PE, Keen N. Abstract 4233: Generation of a Bicycle NK-TICA™, a novel NK cell engaging molecule designed to induce targeted tumor cytotoxicity. Cancer Res 2022. [DOI: 10.1158/1538-7445.am2022-4233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The tumor specific activation of natural killer (NK) cells is an area of active investigation in immune oncology, but to date has relied on complex biologic modalities (e.g., antibodies, fusion proteins, or cell therapies). NK cells are highly responsive immune cells that can detect and eliminate tumor cells and bridge innate to adaptive immune responses. Bicycles® are small (ca.1.5kDa), chemically synthetic, structurally constrained peptides discovered via phage display and optimized using structure-driven design and medicinal chemistry approaches. We have applied the Bicycle platform technology to identify Bicycles® that bind specifically to the key activating receptor, NKp46. When chemically coupled to tumor antigen binding Bicycles, this results in highly potent, antigen-dependent receptor activation and NK cell activation. We term this new class of fully synthetic molecules NK-TICAs and we will describe herein their discovery and evaluation.We demonstrate potent, selective binding of our Bicycles to receptor-expressing cells and the capability of the bifunctional molecule to induce NK cell function in vitro. With Bicycle’s novel NK-TICA™ compound, we demonstrate the engagement of NK cells, the specific activation and function of NK cells, and enhanced tumor cytotoxicity in a tumor target- and dose-dependent manner.In conclusion, NK-TICAs drive NK cell-mediated tumor cell killing and cytokine production in vitro and as such have the potential to catalyze the development of durable anti-tumor immunity in tumor types not well served by current therapies. We hypothesize that utilization of Bicycle NK-TICA™ as a multifunctional immune cell engager will promote the modulation of NK cells, as well as the infiltration and anti-tumor activity of NK cells in solid tumors. The data presented here provide initial proof of concept for the application of our Bicycle technology to drive NK cell-mediated tumor immunity.
Citation Format: Fay J. Dufort, Christopher J. Leitheiser, Gemma Mudd, Julia Kristensson, Alexandra Rezvaya, Katie Gaynor, Sandra Uhlenbroich, Liudvikas Urbonas, Heather Scott, Liuhong Chen, Helen Harrison, Michael Skynner, Kevin McDonnell, Philip E. Brandish, Nicholas Keen. Generation of a Bicycle NK-TICA™, a novel NK cell engaging molecule designed to induce targeted tumor cytotoxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4233.
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Cohen H, Kanakia D, Lahdenranta J, Upadhyaya P, Hurov K, Kristensson J, Jobaliya C, Bannish G, Cotty A, McDonnell K, Hirschberg S, Brandish P, Hazard S, Smethurst D, Keen N, Blakemore SJ. Abstract 1976: Development of a CD137 receptor occupancy assay to support the phase I/II study of BT7480, a Bicycle tumor-targeted immune cell agonist™ ( Bicycle TICA®). Cancer Res 2022. [DOI: 10.1158/1538-7445.am2022-1976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Bicycles are fully synthetic constrained peptides with antibody-like affinities that target selectively, readily penetrate tumor tissue, have relatively short half-lives, and can be chemically linked together to generate multifunctional molecules. BT7480 is a Bicycle TICA® being developed as a first-in-class CD137 therapeutic for the treatment of human cancers associated with Nectin-4 expression which is currently being investigated in an ongoing phase I/II clinical trial. Monitoring target engagement for a given therapeutic can be a key factor in recommending the phase II dose. While flow cytometry-based receptor occupancy (RO) assays are commonly used to monitor target engagement in the clinic, a CD137-specific RO assay presents several important challenges that have historically hampered monitoring RO in the clinic including the dynamic expression of CD137 on unstimulated and stimulated T cells, the low frequency of CD137+ cells in human blood and limited reagents to confidently detect CD137+ cells in the presence of CD137-targeting drugs. To address these challenges, a fit-for-purpose 14-plex flow cytometry panel was developed that incorporates a fluorescently labelled CD137-specific binding Bicycle®. This CD137 Bicycle® was shown to directly compete with BT7480 for binding to CD137, but not with fluorescently labelled anti-CD137 antibody, thereby enabling simultaneous detection of various CD137+ immune cell types as well as receptor occupancy by BT7480 in a single blood sample. Panel performance was tested across blood-based sample matrices routinely used in the clinic including EDTA and Cyto-Chex® blood collection tubes and Cell Preparation Tubes (CPT) (n=3 each). CPT were selected as the optimal sample matrix based on sample viability and highest detection of CD137 antibody+ and CD137 Bicycle® + cells. Ex vivo RO assessments in anti-CD3 stimulated and unstimulated healthy human blood, demonstrated dose-dependent detection of CD137 RO by BT7480 and the detection of >1000 CD137+ cells with sample viability >70% (n=5 each). The optimized method and dose-dependent detection of CD137+ cells and RO by BT7480 was further verified in unstimulated lung cancer patient whole blood samples (n=5). Results from this study represent the first report of a clinic-ready CD137 RO assay and the first flow cytometry assay using fluorescently labelled Bicycle® reagents and demonstrate the utility of the Bicycle® CD137 RO assay to monitor target engagement in the BT7480 first-in-human clinical trial.
Citation Format: Heather Cohen, Drasti Kanakia, Johanna Lahdenranta, Punit Upadhyaya, Kristen Hurov, Julia Kristensson, Chintan Jobaliya, Greg Bannish, Adam Cotty, Kevin McDonnell, Sandra Hirschberg, Phil Brandish, Sebastien Hazard, Dominic Smethurst, Nicholas Keen, Stephen J. Blakemore. Development of a CD137 receptor occupancy assay to support the phase I/II study of BT7480, a Bicycle tumor-targeted immune cell agonist™ (Bicycle TICA®) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1976.
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Hurov K, Lahdenranta J, Upadhyaya P, Haines E, Cohen H, Repash E, Kanakia D, Ma J, Kristensson J, You F, Campbell C, Witty D, Kelly M, Blakemore S, Jeffrey P, McDonnell K, Brandish P, Keen N. BT7480, a novel fully synthetic Bicycle tumor-targeted immune cell agonist™ ( Bicycle TICA™) induces tumor localized CD137 agonism. J Immunother Cancer 2021; 9:jitc-2021-002883. [PMID: 34725211 PMCID: PMC8562524 DOI: 10.1136/jitc-2021-002883] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2021] [Indexed: 12/30/2022] Open
Abstract
Background CD137 (4-1BB) is an immune costimulatory receptor with high therapeutic potential in cancer. We are creating tumor target-dependent CD137 agonists using a novel chemical approach based on fully synthetic constrained bicyclic peptide (Bicycle®) technology. Nectin-4 is overexpressed in multiple human cancers that may benefit from CD137 agonism. To this end, we have developed BT7480, a novel, first-in-class, Nectin-4/CD137 Bicycle tumor-targeted immune cell agonist™ (Bicycle TICA™). Methods Nectin-4 and CD137 co-expression analyses in primary human cancer samples was performed. Chemical conjugation of two CD137 Bicycles to a Nectin-4 Bicycle led to BT7480, which was then evaluated using a suite of in vitro and in vivo assays to characterize its pharmacology and mechanism of action. Results Transcriptional profiling revealed that Nectin-4 and CD137 were co-expressed in a variety of human cancers with high unmet need and spatial proteomic imaging found CD137-expressing immune cells were deeply penetrant within the tumor near Nectin-4-expressing cancer cells. BT7480 binds potently, specifically, and simultaneously to Nectin-4 and CD137. In co-cultures of human peripheral blood mononuclear cells and tumor cells, this co-ligation causes robust Nectin-4-dependent CD137 agonism that is more potent than an anti-CD137 antibody agonist. Treatment of immunocompetent mice bearing Nectin-4-expressing tumors with BT7480 elicited a profound reprogramming of the tumor immune microenvironment including an early and rapid myeloid cell activation that precedes T cell infiltration and upregulation of cytotoxicity-related genes. BT7480 induces complete tumor regressions and resistance to tumor re-challenge. Importantly, antitumor activity is not dependent on continuous high drug levels in the plasma since a once weekly dosing cycle provides maximum antitumor activity despite minimal drug remaining in the plasma after day 2. BT7480 appears well tolerated in both rats and non-human primates at doses far greater than those expected to be clinically relevant, including absence of the hepatic toxicity observed with non-targeted CD137 agonists. Conclusion BT7480 is a highly potent Nectin-4-dependent CD137 agonist that produces complete regressions and antitumor immunity with only intermittent drug exposure in syngeneic mouse tumor models and is well tolerated in preclinical safety species. This work supports the clinical investigation of BT7480 for the treatment of cancer in humans.
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Dufort F, Leitheiser C, Mudd G, Kristensson J, Rezvaya A, Repash E, Haines E, Gaynor K, Uhlenbroich S, Urbonas L, Allen H, Harrison H, Chen L, Brandish P, McDonnell K, Keen N. 789 Generation of a Bicycle NK-TICA™, a novel NK cell engaging molecule to enhance targeted tumor cytotoxicity. J Immunother Cancer 2021. [DOI: 10.1136/jitc-2021-sitc2021.789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BackgroundNatural killer (NK) cells are immune cells that can detect and eliminate tumor cells and bridge innate to adaptive immune responses. Tumor specific activation of NK cells is thus an area of active investigation in immune oncology, but to date has relied on complex biologic modalities (e.g., antibodies, fusion proteins, or cell therapies), each of which has inherent disadvantages in this application. Thus, alternative approaches are warranted. Bicycle® are small (ca. 1.5 kDa), chemically synthetic, structurally constrained peptides discovered via phage display and optimized using structure-driven design and medicinal chemistry approaches. We have now applied this technology to identify Bicycles that bind specifically to the key activating receptors, NKp46 and CD16a. When chemically coupled to tumor antigen binding Bicycles this results in highly potent, antigen-dependent receptor activation and NK cell activation. We term this new class of fully synthetic molecules Bicycle® natural killer- tumor-targeted immune cell agonists (NK-TICAs™) and we will describe their discovery and evaluation in this presentation.MethodsUsing our unique phage display screening platform, we have identified high affinity, selective binders to NKp46 and CD16a. By conjugating the Bicycle® NK cell-engaging binders to a model tumor antigen EphA2-binding Bicycle®, we have developed a bifunctional Bicycle NK-TICA™ molecule. In in vitro functional assays, we evaluated the ability of the Bicycle NK-TICAs™ to induce NK cell activation as well as cell-mediated cytotoxicity and cytokine production in NK-tumor co-culture assays.ResultsWe have developed a novel modular compound with high affinity and selectivity to NK cell receptors with specific tumor targeting capability. We demonstrate potent, selective binding of our Bicycles to receptor-expressing cells and the capability of the bifunctional molecule to induce NK cell function. With Bicycle's novel NK-TICA™ compound, we demonstrate engagement of NK cells, specific activation and function of NK cells, and enhanced EphA2-expressing tumor cytotoxicity, in a dose dependent manner.ConclusionsBicycle NK-TICAs™ are novel therapeutic agents capable of enhancing the landscape of immune oncology. We hypothesize that utilization of Bicycle NK-TICA™ as a multifunctional immune cell engager will promote modulation of NK cells, and infiltration and anti-tumor activity of NK cells in solid tumors. The data presented here provide initial proof of concept for application of the Bicycle technology to drive NK cell-mediated tumor immunity.
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Cohen H, Campbell C, Hurov K, Lahdenranta J, Gelb T, Galbraith D, Rozelle D, Nagy M, Au Q, Parnell E, Brandish P, Hazard S, Smethurst D, Keen N, Blakemore S. 2 Quantitation of CD137 and Nectin-4 expression across multiple tumor types to support indication selection for BT7480, a Bicycle tumor-targeted immune cell agonist™ ( Bicycle TICA™). J Immunother Cancer 2021. [DOI: 10.1136/jitc-2021-sitc2021.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BackgroundBicycles are fully synthetic constrained peptides with antibody-like affinities that target selectively, readily penetrate tumor tissue, have relatively short half-lives, and can be chemically linked together to generate multifunctional molecules. BT7480 is a Bicycle TICA™ that binds both CD137 on immune cells and Nectin-4 on cancer cells to deliver a potent anti-tumor immune signal in Nectin-4 expressing tumors. Nectin-4 has been reported to be highly expressed in a wide range of human solid tumors, however the expression of CD137, abundance and localization of CD137+ immune cells in Nectin-4+ tumors are unknowns. A translational and informatics pipeline was established to interrogate the human tumor microenvironment to identify patient populations most likely to benefit from BT7480, which is being developed as a potential first-in-class molecule for the treatment of high unmet need cancers associated with Nectin-4 expression.MethodsTCGA RNAseq data for Nectin-4 and CD137 were analyzed from ~10,000 samples across 36 human cancers. Using a proprietary Nectin-4 mAb and MultiOmyx™ technology, a 19-plexed immunofluorescence assay was developed to simultaneously quantify the presence of Nectin-4+ and CD137+ cells, identify immune cell subsets and their spatial topography in 43 human tumor FFPE samples from HNSCC, lung, bladder, and breast cancers. Each FFPE slide was presented to a pathologist for tissue annotation and selection of regions of interest for image analysis. Proprietary deep learning-based workflows were applied to identify stroma and tumor regions, individual cells and perform cell classification for phenotypes of interest.ResultsRNA expression analysis indicated co-expression of Nectin-4 and CD137 in several tumor types with >50% tumors within NSCLC, HNSCC, breast, esophageal, and ovarian cancers expressing high levels of both targets. Spatial proteomic studies in HNSCC, lung, breast and bladder cancer samples demonstrated that Nectin-4 and CD137 co-expression at the protein level (>1% positive cells) was detected in 74% samples tested. CD137+ cells in Nectin-4+ tumors were identified as CD4+ T cells (37.6%), CD8+ T cells (16.8%) and CD68+ macrophages (5.9%). A subset of CD137+ cells (32.7%) were found to be deeply tumor penetrant and within close proximity of Nectin-4+ tumor cells across all indications tested.ConclusionsResults from this study support prioritization of indications for BT7480 clinical development and the utility of the MultiOmyx™ assay to monitor Nectin-4 and CD137 expression and to demonstrate proof-of-mechanism for the BT7480 FIH clinical trial expected to start in 2H-2021.
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Upadhyaya P, Mudd G, Hurov K, Lahdenranta J, Repash E, Kristensson J, McDonnell K, Brandish P, Jeffrey P, Keen N. 888 An integrative approach to optimize a synthetic EphA2/CD137 agonist: balancing potency, physiochemical properties, and pharmacokinetics to achieve robust anti-tumor activity. J Immunother Cancer 2021. [DOI: 10.1136/jitc-2021-sitc2021.888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BackgroundCD137 (4-1BB) is a resurging target in immunotherapy after the first generation of monoclonal antibodies were limited by hepatotoxicity1 or lack of efficacy.2 A new generation of CD137 agonists are now in clinical development but they exclusively utilize large molecules derived from recombinant technology and are associated with long circulating terminal half-lives.3–6 Unlike checkpoint inhibition where complete saturation of the receptors drives the reversal of immunosuppression, intermittent target engagement that reflects the physiological context of T cell co-stimulation may be more appropriate for a CD137 agonist.7 Bicyclic peptides or Bicycles are a class of small (MW~2kDa), highly constrained peptides characterized by formation of two loops cyclized around a symmetric scaffold. To develop a differentiated tumor antigen dependent CD137 agonist for treating EphA2 expressing solid tumors, we integrated structure activity relationship (SAR) data from biochemical binding studies and in-vitro and in-vivo models to understand the relationship between exposure, target engagement and preclinical efficacy.MethodsOver 150 different EphA2/CD137 tumor-targeted immune cell agonists (Bicycle TICAs) were synthesized by linking Bicycle® binders to EphA2 to those binding CD137.8 The molecules were assessed in vitro using a CD137 reporter assay and by measuring cytokine production from primary human PBMC in tumor cell co-cultures. The pharmacokinetics were evaluated in rodents using Phoenix WinNonlin. The in vivo activity was determined in syngeneic mouse tumor models by measuring tumor growth kinetics and using tumor immune cell and transcriptional profiling by IHC and NanoString.ResultsEvaluation of the Bicycle TICAs in co-culture assays with EphA2-expressing tumor cell lines and Jurkat reporter cells overexpressing CD137 or human PBMCs demonstrated that constructs bearing two CD137 binding Bicycles to one EphA2 binding Bicycle (1:2 format) were more potent than the 1:1 format.8 Several Bicycle TICAs with amino acid substitutions to the EphA2 binding Bicycle maintained sub-nanomolar potency in-vitro and exhibited a plasma terminal half-life (t1/2) in rodents ranging from 0.4 and 4.0 h. Modifications that conferred aqueous solubility of greater than 10 mg/mL were considered suitable for further development. Treatment of MC38 tumors in immunocompetent mice with this series of molecules demonstrated that low MW Bicycle TICAs with sub-nanomolar potency and a t½ of ~1 h in mouse maintained target coverages necessary to produce robust modulation of the tumor immune microenvironment and tumor regression.ConclusionsA differentiated EphA2-dependent CD137 agonist was developed that exploits intermittent rather than continuous exposure for robust anti-tumor activity.ReferencesSegal NH, Logan TF, Hodi FS, et al. Results from an integrated safety analysis of urelumab, an agonist anti-CD137 monoclonal antibody. Clin Cancer Res 2017;23(8):1929–1936.Segal NH, Aiwu RH, Toshihiko D, et al. Phase I study of single-agent utomilumab (PF-05082566), a 4-1BB/CD137 agonist, in patients with advanced cancer. Clin Cancer Res 2018;24(8):1816–1823.Chester C, Sanmamed MF, Wang J, Melero I. Immunotherapy targeting 4-1BB: mechanistic rationale, clinical results, and future strategies. Blood 2018;131(1):49–57.Hinner MJ, Aiba RSB, Jaquin TJ, et al. Tumor-localized costimulatory T-cell engagement by the 4-1BB/HER2 bispecific antibody-anticalin fusion PRS-343. Clin Cancer Res 2019;25(19):5878–5889.Claus C, Ferrara, C, Xu W, et al. Tumor-targeted 4-1BB agonists for combination with T cell bispecific antibodies as off-the-shelf therapy. Sci Transl Med 2019;11(496):eaav5989.Eskiocak U, Guzman W, Wolf B, et al. Differentiated agonistic antibody targeting CD137 eradicates large tumors without hepatotoxicity. JCI Insight 2020;5(5):e133647.Mayes PA, Hance KW, Hoos A. The promise and challenges of immune agonist antibody development in cancer. Nat Rev Drug Discov 2018;17:509–27.Upadhyaya P, Lahdenranta J, Hurov K, et al. Anticancer immunity induced by a synthetic tumor-targeted CD137 agonist. J Immunother Cancer 2021;9:e001762.
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Hurov K, Lahdenranta J, Upadhyaya P, Kanakia D, Repash E, You F, Ma J, Haines E, Cohen H, McDonnell K, Brandish PE, Jeffrey P, Keen N. Abstract 1728: Nectin-4-dependent immune cell stimulation and anti-tumor efficacy by BT7480, a Nectin-4/CD137 Bicycle®tumor-targeted immune cell agonist (TICA™). Cancer Res 2021. [DOI: 10.1158/1538-7445.am2021-1728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The costimulatory immune receptor CD137 (4-1BB/TNFRSF9) has been recognized for its potential as a drug target in cancer alongside checkpoint inhibitors, but this promise has not been realized for patients due to toxicity (principally hepatic toxicity) and limited efficacy of current biologic based therapies [1,2]. Thus, alternative approaches to this important target are warranted. Next generation strategies are focused on bispecific approaches aimed at promoting target-mediated clustering of CD137 to limit systemic and liver toxicities [3-4]. Bicycles® are small, structurally constrained peptides discovered via phage display and optimized using structure-driven design and medicinal chemistry approaches. We have applied this disruptive technology to the problem, identifying CD137 Bicycles and chemically linking these to tumor antigen binding Bicycles to generate multifunctional “bispecific” like molecules that induce tumor antigen dependent, tumor localized agonism of CD137. We termed these Tumor-targeted Immune Cell Agonists (TICAs™). BT7480 is a TICA that was designed to deliver highly potent CD137 agonism to Nectin-4 overexpressing tumor tissue. Nectin-4 is expressed at high levels in bladder, breast, and lung tumors and at low levels in normal tissue and thus is an attractive target for localized immunotherapy. BT7480 binds potently to Nectin-4 expressing cells and engages CD137 expressed on immune cells in trans, leading to robust Nectin-4-dependent CD137 agonism in primary human PBMC/tumor cell co-culture assays. Treatment of Nectin-4 expressing tumors in immunocompetent mice with BT7480 induces complete tumor regressions and subsequent resistance to tumor re-challenge. Using flow cytometry, immunohistochemistry, and transcriptional profiling, we demonstrate that BT7480 treatment leads to profound reprogramming of the tumor immune microenvironment including increased T cell infiltration and upregulation of a cytotoxic cell gene signature. We also observed an increase in the macrophage cell score and interestingly, time course evaluation revealed a unique mechanism of action - rapid activation of myeloid cells (<24h) concomitant with a pulse of chemokine and cytokine secretion peaking at 2-3 days, leading to a dramatic infiltration of cytotoxic T cells on days 4-5. This is distinct from the reported clinical behavior of checkpoint inhibitors. In summary, BT7480 is a novel Nectin-4/CD137 TICA that represents a new generation of chemically synthetic tumor antigen targeted CD137 agonists and the compound is currently in preclinical development. 1. Segal NH, Logan TF, Hodi FS, et al. Clin Cancer Res. 2017;23(8):1929-1936. 2. Chester et al. Blood 2018;131(1): 49-57. 3. Hinner et al. Clin Cancer Res. 2019; 25(19): 5878-5889. 4. Claus C, Ferrara, C, Xu W, et al. Sci Transl Med. 2019; 11(496): eaav5989.
Citation Format: Kristen Hurov, Johanna Lahdenranta, Punit Upadhyaya, Drasti Kanakia, Elizabeth Repash, Fanglei You, Jun Ma, Eric Haines, Heather Cohen, Kevin McDonnell, Philip E. Brandish, Phil Jeffrey, Nicholas Keen. Nectin-4-dependent immune cell stimulation and anti-tumor efficacy by BT7480, a Nectin-4/CD137 Bicycle®tumor-targeted immune cell agonist (TICA™) [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 1728.
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Lahdenranta J, Bennett G, Huxley P, Mudd G, Upadhyaya P, Jeffrey P, Keen N. Abstract 1319: Rapid accumulation of cytotoxic payload in tumor tissue drives BT5528 activity in tumor models. Cancer Res 2021. [DOI: 10.1158/1538-7445.am2021-1319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
BT5528 was developed as a Bicycle® toxin conjugate to deliver monomethyl auristatin E (MMAE) -payload to EphA2 overexpressing tumors. It consists of a bicyclic peptide targeting the tumor antigen EphA2, linked to the cytotoxin MMAE via a molecular spacer and cleavable linker. Administration of BT5528 results in rapid uptake of payload into EphA2 overexpressing xenograft tumors associated with persistent toxin levels in tumor tissue and limited systemic exposure of both parent drug and payload (1). BT5528 showed a favorable preclinical profile supporting the initiation of a first-in-human Phase I/II study (NCT04180371) to investigate safety and efficacy of BT5528 in indications with evidence of EphA2 expression including non-small-cell lung cancer (NSCLC), ovarian cancer, triple-negative breast cancer (TNBC), gastric/upper gastrointestinal (GI), pancreatic and urothelial cancers (2). We have used EphA2 overexpressing tumor xenograft models in both mice and rats to elucidate the relative differences between toxin payload delivery and systemic exposure of BT5528. Comparison of payload-delivery and systemic exposure from EphA2 -targeted Bicycle toxin conjugate and antibody-drug conjugate (ADC) demonstrate the differentiation of these toxin-payload delivery platforms. ADC payload delivery depends upon a sustained plateau-like pharmacokinetic (PK) profile that exposes target and potentially nontarget organs to intact ADC for several days. In contrast, BT5528 achieves prolonged toxin delivery to tumors, following transient exposure in plasma of less than one hour. A Phase I/II study of BT5528 in patients with solid tumors is ongoing, which will investigate if this PK novel, differentiated pharmacokinetic profile, unique to Bicycle toxin conjugates, gives rise to a favorable balance of efficacy and safety. References: 1. Bennett et al. Mol. Cancer Ther. 2020;19:1385-942. 2. Bendell et al. TPS3655 Journal of Clinical Oncology 38, no. 15_suppl
Citation Format: Johanna Lahdenranta, Gavin Bennett, Philip Huxley, Gemma Mudd, Punit Upadhyaya, Phil Jeffrey, Nicholas Keen. Rapid accumulation of cytotoxic payload in tumor tissue drives BT5528 activity in tumor models [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 1319.
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Lahdenranta J, Blakemore SJ, Hurov K, Grenley MO, Upadhyaya P, Campbell C, Repash E, Haines E, Brandish PE, Klinghoffer RA, Keen N. Abstract 1724: Microinjection of Nectin-4/CD137 tumor-targeted immune cell agonist (TICA™) activates the local tumor microenvironment. Cancer Res 2021. [DOI: 10.1158/1538-7445.am2021-1724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
A new generation of both systemic and targeted CD137 agonists are entering clinical development following agonistic anti-CD137 (4-1BB) antibody development nearly a decade ago. However, each of these molecules rely on biologic agents with potentially suboptimal properties for CD137 agonism due to their relatively large size and long circulating half-lives which may limit their tissue penetration, cause sustained agonism resulting in overstimulation and activation-induced lymphocyte cell death. Fully synthetic constrained bicyclic peptides (Bicycles™) with antibody-like affinities and target selectivity are uniquely suited to circumvent limitations of other targeted CD137 agonistic therapeutics. BT7480 and BCY11864 are tumor targeted immune cell agonists (TICA) designed to deliver a highly potent CD137 agonist to Nectin-4 overexpressing tumors with a flexible dosing schedule maximizing anti-tumor activity while circumventing the need for continuous systemic exposure. The Comparative In Vivo Oncology (CIVO) platform has been developed to enable in situ investigation of multiple microdosed drugs simultaneously in human tumors with safety and feasibility of this platform recently demonstrated in patients with soft tissue sarcomas. CIVO percutaneously injects drug microdoses directly into tumor tissue as trackable columns where tissue can be analyzed after resection for the effect of the drug treatment in the tumor. Here we report on an evaluation of the feasibility of using the CIVO -platform to demonstrate the mechanism of action of our tumor target-dependent CD137 agonist TICAs. Both BT7480 and BCY11864 demonstrate extremely potent Nectin-4-dependent CD137 agonism in primary human PBMC/tumor cell co-culture assays. Systemic administration of BT7480 in Nectin-4 expressing tumors in immunocompetent mice leads to profound reprogramming of the tumor immune microenvironment including a rapid increase in T cell chemotactic cytokine transcripts and macrophage gene signatures followed by an increase in cytotoxic cell gene signature and increase in intratumoral CD8+ T cells. CIVO was used to demonstrate the in vivo mechanism of action of a Nectin-4/CD137 TICA. Micro-injection of BCY11864 into Nectin-4 expressing tumors in immunocompetent mice led to dose dependent induction of immune activation markers in the tumor microenvironment and activation of the tumor resident cytotoxic T cells was evident 24 hours after BCY11864 micro-injection. Akin to our findings with transcriptional profiling of the tumor response to BT7480, BCY11864 activity was shown not to be limited to T cells but also included other CD137 positive cell populations such as myeloid and NK cells. We hypothesize that tumor targeted CD137 agonism may lead to initial myeloid cell response that enhances the cytotoxic T cell recruitment and activation in the tumor tissue.
Citation Format: Johanna Lahdenranta, Stephen J. Blakemore, Kristen Hurov, Marc O. Grenley, Punit Upadhyaya, Carly Campbell, Elizabeth Repash, Eric Haines, Philip E. Brandish, Richard A. Klinghoffer, Nicholas Keen. Microinjection of Nectin-4/CD137 tumor-targeted immune cell agonist (TICA™) activates the local tumor microenvironment [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 1724.
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Kanakia DN, Upadhyaya P, Lahdenranta J, Repash E, Haines E, McDonnell K, Hurov K, Brandish P, Keen N. Abstract PO076: Development of a CD137 (4-1BB) receptor occupancy assay using fluorescently labelled Bicycles®. Cancer Immunol Res 2021. [DOI: 10.1158/2326-6074.tumimm20-po076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Receptor occupancy (RO) assays are designed to quantify the binding of therapeutics to their cell surface targets and are frequently used to generate both pre-clinical and clinical pharmacodynamic biomarker data. Flow cytometry is a commonly used technique to measure receptor occupancy on immune cell populations within fresh blood specimens. Yet, receptor occupancy assays are subject to numerous technical and logistical challenges. To ensure that reliable and high-quality results are generated from receptor occupancy assays, careful assay design and key reagent selection, characterization, and utilization are of critical importance. Antibodies are commonly conjugated with fluorophores and used in receptor occupancy assays for related therapeutics. Bicycles® are a new therapeutic modality - fully synthetic, constrained bicyclic peptides with high affinity and excellent target selectivity. Here, we describe a novel utility for fluorescently-labeled Bicycles in the development of a CD137 (4-1BB) receptor occupancy assay. CD137 is a member of the TNFR superfamily involved in stimulation of several immune cell types, including T cells and NK cells. CD137 is well validated pre-clinically, as agonism with anti-CD137 antibodies is effective in vivo, however, clinical utility to date has been limited by dose dependent hepatotoxicity. We have demonstrated that tumor-targeted immune cell agonists (TICAsTM) comprised of CD137 binding Bicycles coupled to tumor antigen binding Bicycles exert anti tumoral properties with a favorable safety profile. Here, we demonstrate another functionality for the Bicycle platform, as a measurement of CD137 TICA target engagement and receptor occupancy. Using fluorescently-labeled CD137 Bicycles, we measured RO on immune populations in isolated human peripheral blood mononuclear cells (PBMCs), as well as in whole blood. The assay shows high specificity as no Bicycle binding was observed in CD137 negative cell populations. Additionally, RO was shown to be dependent on the presence of CD137-binding Bicycles. Together, this novel approach of measuring receptor occupancy may be used to inform on both the pre-clinical and clinical therapeutic properties of Bicycle TICAs.
Citation Format: Drasti N. Kanakia, Punit Upadhyaya, Johanna Lahdenranta, Elizabeth Repash, Eric Haines, Kevin McDonnell, Kristen Hurov, Philip Brandish, Nicholas Keen. Development of a CD137 (4-1BB) receptor occupancy assay using fluorescently labelled Bicycles® [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO076.
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Repash EM, Upadhyaya P, Lahdenranta J, Kublin J, Ma J, Kleyman M, Chen L, Haines E, Battula S, McDonnell K, Hurov K, Brandish P, Keen N. Abstract PO077: BT7480, a novel fully synthetic tumor-targeted immune cell agonist (TICA™) induces tumor localized 4-1BB agonism. Cancer Immunol Res 2021. [DOI: 10.1158/2326-6074.tumimm20-po077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Harnessing costimulatory molecules expressed on T and NK cells namely 4-1BB (CD137/TNFRSF9) is ideal for cancer immunotherapy. Despite promise preclinically, 4-1BB agonistic antibodies, were unable to demarcate hepatoxicity from efficacy in the clinic. Bispecific approaches promote target-mediated clustering of 4-1BB while limiting systemic and liver toxicity. Bicycles® are novel, fully synthetic, constrained bicyclic peptides with high affinity and selectivity to their targets. Their small size (~2kDa) and tunable pharmacokinetic parameters allow Bicycles to have superior tumor penetration and de-risk hepatoxicity concerns due to a renal clearance mechanism. We hypothesized that clustering and activation of 4-1BB could be attained by conjugating a 4-1BB binding Bicycle to a tumor antigen targeting Bicycle promoting a potent tumor-localized immune response. BT7480 is a tumor-targeted immune cell agonist (TICA™) targeting Nectin-4 and agonizing 4-1BB. Nectin-4 (PVRL4) is highly expressed in numerous tumor indications with unmet clinical needs. In an engineered 4-1BB reporter system, we found BT7480 induced potent 4-1BB agonism correlating to target antigen surface expression on the co-cultured tumor cells. Moreover, BT7480 induces cytokine secretion, including interleukin-2 and interferon gamma, in immune cell co-culture in the presence of tumor antigen. This activity is strictly dependent on Nectin-4 expression on tumor cells and the ability of the TICA to bind to both Nectin-4 and 4-1BB. In a MC38 (Nectin-4-expressing) syngeneic mouse model, intermittent dosing of BT7480 led to robust anti-tumor efficacy (22 out of 24 complete responders (CRs)). Importantly, a memory response was established in CR mice as resistance to a re-challenge with MC38 tumors was observed. Additionally, BT7480 led to increased intratumoral T cell infiltration without elevation of liver enzymes in a CT26 (Nectin-4-expressing) syngeneic mouse model. In non-human primates (NHPs), BT7480 exhibits dose linear exposure and is well tolerated up to 10mpk. BT7480 represents a new generation of chemically synthetic tumor antigen targeted 4-1BB agonists with potent efficacy and a favorable safety profile.
Citation Format: Elizabeth M. Repash, Punit Upadhyaya, Johanna Lahdenranta, Jessica Kublin, Jun Ma, Marianna Kleyman, Liuhong Chen, Eric Haines, Sailaja Battula, Kevin McDonnell, Kristen Hurov, Philip Brandish, Nicholas Keen. BT7480, a novel fully synthetic tumor-targeted immune cell agonist (TICA™) induces tumor localized 4-1BB agonism [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO077.
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Upadhyaya P, Lahdenranta J, Hurov K, Battula S, Dods R, Haines E, Kleyman M, Kristensson J, Kublin J, Lani R, Ma J, Mudd G, Repash E, Van Rietschoten K, Stephen T, You F, Harrison H, Chen L, McDonnell K, Brandish P, Keen N. Anticancer immunity induced by a synthetic tumor-targeted CD137 agonist. J Immunother Cancer 2021; 9:jitc-2020-001762. [PMID: 33500260 PMCID: PMC7839861 DOI: 10.1136/jitc-2020-001762] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2020] [Indexed: 12/13/2022] Open
Abstract
Background In contrast to immune checkpoint inhibitors, the use of antibodies as agonists of immune costimulatory receptors as cancer therapeutics has largely failed. We sought to address this problem using a new class of modular synthetic drugs, termed tumor-targeted immune cell agonists (TICAs), based on constrained bicyclic peptides (Bicycles). Methods Phage libraries displaying Bicycles were panned for binders against tumor necrosis factor (TNF) superfamily receptors CD137 and OX40, and tumor antigens EphA2, Nectin-4 and programmed death ligand 1. The CD137 and OX40 Bicycles were chemically conjugated to tumor antigen Bicycles with different linkers and stoichiometric ratios of binders to obtain a library of low molecular weight TICAs (MW <8 kDa). The TICAs were evaluated in a suite of in vitro and in vivo assays to characterize their pharmacology and mechanism of action. Results Linking Bicycles against costimulatory receptors (e.g., CD137) to Bicycles against tumor antigens (e.g., EphA2) created potent agonists that activated the receptors selectively in the presence of tumor cells expressing these antigens. An EphA2/CD137 TICA (BCY12491) efficiently costimulated human peripheral blood mononuclear cells in vitro in the presence of EphA2 expressing tumor cell lines as measured by the increased secretion of interferon γ and interleukin-2. Treatment of C57/Bl6 mice transgenic for the human CD137 extracellular domain (huCD137) bearing EphA2-expressing MC38 tumors with BCY12491 resulted in the infiltration of CD8+ T cells, elimination of tumors and generation of immunological memory. BCY12491 was cleared quickly from the circulation (plasma t1/2 in mice of 1–2 hr), yet intermittent dosing proved effective. Conclusion Tumor target-dependent CD137 agonism using a novel chemical approach (TICAs) afforded elimination of tumors with only intermittent dosing suggesting potential for a wide therapeutic index in humans. This work unlocks a new path to effective cancer immunotherapy via agonism of TNF superfamily receptors.
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Battula S, Mudd G, Upadhyaya P, Kristensson J, Kleyman M, Repash E, Kublin J, Ma J, Haines E, Hurov K, Chen L, Lahdenranta J, Beswick P, McDonnell K, Keen N. Abstract 6703: A fully synthetic EphA2/4-1BB tumor-targeted immune cell agonist (TICATM) induces tumor localized 4-1BB agonism. Cancer Res 2020. [DOI: 10.1158/1538-7445.am2020-6703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
4-1BB (CD137) is a member of the TNFR superfamily involved in stimulation of several immune cell types, including T cells and NK cells. CD137 is well validated pre-clinically, as agonism with anti-CD137 antibodies is effective in vivo [1], however, clinical utility to date has been limited by dose dependent hepatotoxicity. Bicycles® are a new therapeutic modality - fully synthetic, constrained bicyclic peptides with high affinity and excellent target selectivity.
We hypothesized that Bicycle CD137 agonists that lack Fc domains and exhibit rapid renal elimination may induce CD137 mediated anti-tumor activity while avoiding liver toxicity. Initially, we identified and optimized CD137 specific Bicycle agonists which, when multimerized together, induced CD137 mediated anti-tumor activity [2]. We have built on this initial approach and developed second generation molecules to enable potent stimulation of immune cells exclusively at the tumor site. These tumor-targeted immune cell agonists (TICAsTM) comprise CD137 binding Bicycles coupled to tumor antigen binding Bicycles.
Erythropoietin-producing hepatocellular A2 receptor (EphA2) is a tumor target overexpressed in several human cancers and its overexpression correlates with poor clinical prognosis. Here, we present new preclinical data demonstrating the potent immunomodulatory activity of dual targeting EphA2/CD137 TICAs. EphA2/CD137 TICAs engage EphA2 and CD137 with high affinity resulting in picomolar potency in co-culture assays consisting of cancer cell lines endogenously expressing EphA2, and CD137 Jurkat NF-kB/luciferase reporter cells. Moreover, EphA2/CD137 TICAs potentiate cytokine secretion (e.g. IFNγ) in immune cell co-culture experiments and promote caspase activity in T cell mediated cell killing assays. In vivo, EphA2/CD137 TICA (BCY9173), when dosed at 15 mg/kg (BID) to PBMC-humanized mice bearing HT29 xenografts, increased CD8+ T cells in tumors but not in plasma, suggesting local tumor target specific stimulation of T cells without systemic CD137 agonism. Intermittent dosing with various regimens of BCY12491, an EphA2/CD137 TICA, demonstrated robust anti-tumor activity including complete responses (CR) in 10/12 animals in a syngeneic humanized CD137 MC38 mouse model. Importantly, CR mice are resistant to re-challenge with MC38 tumor cells demonstrating a memory response, a phenomenon which has been previously reported for CD137 agonists [1]. Our EphA2/CD137 TICAs have shown the potential to precisely and potently stimulate immune cells in tumors without systemic immune activation.
This provides a strong rationale to further develop first-in-class Bicycle TICAs to potentially treat EphA2 expressing cancers.
References
1. Melero I, Shuford WW, Newby SA, Aruffo A, Ledbetter JA, Hellström KE, Mittler RS, Chen L. Monoclonal antibodies against the 4-1BB T-cell activation molecule eradicate established tumors. Nat Med. 1997; 3(6): 682-5
2. K. Hurov, P. Upadhyaya, J. Kublin, M. Kleyman, X. Zhou, J. Kristensson, G. Mudd, K. Rietschoten, S. Watcham, R. Lani, W. F. An, T. Stephen, E. Haines, J. Lahdenranta, L. Chen, S. Battula, K. McDonnell, P. Park, and N. Keen. Activation of 4-1BB using multivalent and tumour targeted bicyclic peptides; Poster 2019 Annual AACR meeting, Cancer Research, DOI: 10.1158/1538-7445.AM2019-3257 Published July 2019
Citation Format: Sailaja Battula, Gemma Mudd, Punit Upadhyaya, Julia Kristensson, Marianna Kleyman, Elizabeth Repash, Jessica Kublin, Jun Ma, Eric Haines, Kristen Hurov, Liuhong Chen, Johanna Lahdenranta, Paul Beswick, Kevin McDonnell, Nicholas Keen. A fully synthetic EphA2/4-1BB tumor-targeted immune cell agonist (TICATM) induces tumor localized 4-1BB agonism [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 6703.
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Hurov K, Upadhyaya P, Lahdenranta J, Kublin J, Ma J, Repash E, Kleyman M, Kristensson J, Chen L, Haines E, Battula S, McDonnell K, Keen N. Abstract 5552: BT7480, a novel fully synthetic tumor-targeted immune cell agonist (TICATM) induces tumor localized 4-1BB agonism. Cancer Res 2020. [DOI: 10.1158/1538-7445.am2020-5552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Costimulatory molecules expressed on activated T and NK cells such as 4-1BB (CD137/TNFRSF9) can be leveraged for cancer immunotherapy. Despite compelling preclinical data, 4-1BB agonistic antibodies have been hampered by failure to delineate hepatoxicity from efficacy in the clinic [1,2]. Next generation strategies are focused on bispecific approaches aimed at promoting target-mediated clustering of 4-1BB to limit systemic and liver effects [3,4]. Bicycles® are fully synthetic, constrained bicyclic peptides that have antibody-like affinity and selectivity to their targets. Unlike traditional biologic approaches, the small size (~2 kDa) and tunable pharmacokinetic (PK) parameters of Bicycles enable superior tumor penetration and allow exploration into the relationship between pulsatile dosing and 4-1BB activation while de-risking hepatoxicity concerns due to a differentiated renal elimination mechanism combined with a tumor-localized immune response. We hypothesized that clustering and activation of 4-1BB could be achieved by conjugating a 4-1BB binding Bicycle to a tumor antigen targeting Bicycle. BT7480 is a tumor-targeted immune cell agonist (TICATM) targeting Nectin-4 and agonizing 4-1BB. Nectin-4 (PVRL4) is highly expressed on numerous tumors with unmet medical need, including bladder, pancreatic, breast, ovarian, esophageal, and lung. BT7480 exhibits highly potent 4-1BB agonism in an engineered 4-1BB reporter system that correlates with Nectin-4 surface expression on the co-cultured tumor cells. In addition, BT7480 induces robust production of interleukin-2 (IL-2) and interferon gamma (IFNγ) in primary PBMC/tumor cell co-culture assays. This activity is strictly dependent on the tumor cells expressing Nectin-4 and on the ability of the TICA to bind to both Nectin-4 and 4-1BB. Nectin-4/4-1BB TICAs are also target-specific immune cell stimulators of patient-derived lung tumors with an intact immune microenvironment. Intermittent dosing of BT7480 led to robust anti-tumor efficacy with 22 out of 24 complete responders (CRs) in a MC38 (Nectin-4-expressing) syngeneic mouse model. Importantly, a memory response was established as the CR mice were resistant to re-challenge with MC38 tumors. Additionally, BT7480 led to increased intratumoral T cell infiltration without elevation of liver enzymes in a CT26 (Nectin-4-expressing) syngeneic mouse model. In non-human primates (NHPs), BT7480 exhibits dose linear exposure and is well tolerated up to 10mpk. Further dose-range finding and safety analysis in NHPs is currently ongoing. BT7480 represents a new generation of chemically synthetic tumor antigen targeted 4-1BB agonists. References 1. Segal NH, Logan TF, Hodi FS, et al. Results from an integrated safety analysis of urelumab, an agonist anti-CD137 monoclonal antibody. Clin Cancer Res. 2017;23(8):1929-1936. 2. Chester et al. Immunotherapy targeting 4-1BB: mechanistic rationale, clinical results, and future strategies. Blood 2018;131(1): 49-57. 3. Hinner et al. Tumor-localized costimulatory T-cell engagement by the 4-1BB/HER2 bispecific antibody-anticalin fusion PRS-343. Clin Cancer Res. 2019; 25(19): 5878-5889. 4. Claus C, Ferrara, C, Xu W, et al. Tumor-targeted 4-1BB agonists for combination with T cell bispecific antibodies as off-the-shelf therapy. Sci Transl Med. 2019; 11(496): eaav5989.
Citation Format: Kristen Hurov, Punit Upadhyaya, Johanna Lahdenranta, Jessica Kublin, Jun Ma, Elizabeth Repash, Marianna Kleyman, Julia Kristensson, Liuhong Chen, Eric Haines, Sailaja Battula, Kevin McDonnell, Nicholas Keen. BT7480, a novel fully synthetic tumor-targeted immune cell agonist (TICATM) induces tumor localized 4-1BB agonism [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 5552.
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Bennett G, Brown A, Mudd G, Huxley P, Van Rietschoten K, Pavan S, Chen L, Watcham S, Lahdenranta J, Keen N. MMAE Delivery Using the Bicycle Toxin Conjugate BT5528. Mol Cancer Ther 2020; 19:1385-1394. [PMID: 32398269 DOI: 10.1158/1535-7163.mct-19-1092] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/24/2020] [Accepted: 04/29/2020] [Indexed: 11/16/2022]
Abstract
The EphA2 receptor is found at high levels in tumors and low levels in normal tissue and high EphA2 expression in biopsies is a predictor of poor outcome in patients. Drug discovery groups have therefore sought to develop EphA2-based therapies using small molecule, peptide, and nanoparticle-based approaches (1-3). However, until now only EphA2-targeting antibody-drug conjugates (ADC) have entered clinical development. For example, MEDI-547 is an EphA2-targeting ADC that displayed encouraging antitumor activity in preclinical models and progressed to phase I clinical testing in man. Here we describe the development of BT5528, a bicyclic peptide ("Bicycle") conjugated to the auristatin derivative maleimidocaproyl-monomethyl auristatin E to generate the Bicycle toxin conjugate BT5528. The report compares and contrasts the Pharmacokinetics (PK) characteristics of antibody and Bicycle-based targeting systems and discusses how the PK and payload characteristics of different delivery systems impact the efficacy-toxicity trade off which is key to the development of successful cancer therapies. We show that BT5528 gives rise to rapid update into tumors and fast renal elimination followed by persistent toxin levels in tumors without prolonged exposure of parent drug in the vasculature. This fast in, fast out kinetics gave rise to more favorable toxicology findings in rats and monkeys than were observed with MEDI-547 in preclinical and clinical studies.Graphical Abstract: http://mct.aacrjournals.org/content/molcanther/19/7/1385/F1.large.jpg.
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Rigby M, Beswick P, Mudd G, Rietschoten KV, Chen L, Watcham SM, Allen H, Brown A, Harrison H, Bennett G, Jeffrey P, Park PU, Koehler M, Keen N. Abstract 4479: BT8009: A bicyclic peptide toxin conjugate targeting Nectin-4 (PVRL4) displays efficacy in preclinical tumor models. Cancer Res 2019. [DOI: 10.1158/1538-7445.am2019-4479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
We have identified a Nectin-4 targeting peptide for delivery of cytotoxic agents to Nectin-4 expressing tumors. Nectin-4 is a cell adhesion molecule, that is highly expressed in certain tumor types, including bladder, TNBC and NSCLC, but has a restricted distribution in normal tissue. Bicycles® are small (1.5kDa) fully synthetic, structurally constrained, peptide drugs that combine the affinity of antibodies with the pharmacokinetic properties of small molecules. The Bicycle phage display platform was utilised to rapidly identify a high affinity (18 nM) and highly selective bicyclic Nectin-4 binding peptide. Synthetic modification of the initial lead peptide improved affinity (0.3 nM), hydrophilicity and stability. The optimised peptide is conjugated through an inert sarcosine spacer chain and a cleavable linker to the toxin MMAE, to form the Bicycle Toxin Conjugate (BTC) BT8009. Once bound to cell surface Nectin-4, the linker system is cleaved by peptidases (e.g. cathepsin B) upregulated in the tumor micro environment. Full structure of BT8009 will be disclosed within the presentation. Fluorescence polarisation and surface plasmon resonance show BT8009 has low nanomolar affinity (3nM) for Nectin-4 and high selectivity (>1000 fold) over Nectins 1-3, and the 5 nectin-like, family members. Good affinity for the cognate native protein is maintained across the preclinical safety species. High content imaging of cultures of MDA-MB-468 cells, demonstrates binding of the BTC to cell membrane. In vivo, BT8009 is well tolerated in mouse and rat and shows regressions across a range of cell and patient derived xenograft models. Efficacy correlates with the expression level of Nectin-4 on the tumor cells, and the dose delivered. In the MDA-MB-468 (TNBC) CDX model full tumor regression was seen with weekly i.v. administration of 3 mg/k g i.v. (4 doses), with no tumor regrowth out to 70 days post last dose. Similar efficacy was seen in two NSCLC PDX models (adenocarcinoma and squamous cell carcinoma) with full regression attained in both. Near full regression was seen in a squamous cell esophageal cancer PDX. Larger tumors show a similar degree of sensitivity to the BTC, with rapid tumor regression from a volume of 800 mm3. As a small peptide BT8009 undergoes rapid clearance from the plasma with minimal exposure to non-targeted organs. After a single dose, MMAE has been shown to be retained within tumor tissue in excess of 60 h, at exposure levels significantly greater than corresponding plasma and other tissue levels. Bicycle Toxin Conjugates represent a novel treatment modality for nectin-4 expressing tumors with excellent efficacy in several mouse xenograft models.
Citation Format: Mike Rigby, Paul Beswick, Gemma Mudd, Katerine Van Rietschoten, Liuhong Chen, Sophie M. Watcham, Heather Allen, Amy Brown, Helen Harrison, Gavin Bennett, Phil Jeffrey, Peter U. Park, Maria Koehler, Nicholas Keen. BT8009: A bicyclic peptide toxin conjugate targeting Nectin-4 (PVRL4) displays efficacy in preclinical tumor models [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 4479.
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Hurov KE, Upadhyaya P, Kublin J, Zhou X, Kristensson J, Lani R, Mudd G, Rietschoten KV, An F, Lahdenranta J, Chen L, Bennett G, McDonnell K, Park P, Keen N. Abstract 3257: Activation of CD137 using multivalent and tumor targeted Bicyclic peptides. Cancer Res 2019. [DOI: 10.1158/1538-7445.am2019-3257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
CD137 (4-1BB/TNFRSF9) is a costimulatory T-cell receptor belonging to the TNF receptor superfamily. Agonistic anti-CD137 antibodies have shown potent, often curative anti-tumor activity in preclinical models. Two human anti-CD137 antibodies, urelumab and utomilumab are currently undergoing clinical testing. Urelumab has shown several single-agent, partial responses, but its use has been hampered by hepatoxicity, while utomilumab has shown little or no single agent activity.
Bicycles® are a new class of drugs - fully synthetic, constrained bicyclic peptides that combine the attributes of antibodies, small molecules, and peptides by delivering high affinity, selectivity, and rapid clearance. Their small size (1.5-2 kDa) delivers advantages in tumor penetration, and renal elimination may avoid the liver and GI toxicity often associated with other drug modalities, including certain antibodies. We hypothesized that fully synthetic Bicycle CD137 agonists with rapid clearance, minimal liver exposure and no Fc receptor interaction may induce CD137 mediated anti-tumor activity while avoiding liver toxicity.
A high affinity lead BCY3814 (KD ~30 nM) that binds to the CD137 ligand-binding site was identified. CD137 activation requires receptor crosslinking, thus multivalent binding would be expected to recapitulate the action of the natural trimeric ligand. We envisioned that CD137 agonism could be achieved directly by using multimeric CD137 Bicycles or in a tumor targeted fashion with bispecific or “heterotandem” Bicycles. The synthetic simplicity and highly modular nature of the Bicycle® platform enabled us to rapidly explore both formats.
To generate a “pure” CD137 agonist we synthesized >50 different multimeric variants of BCY3814 with chemical linkers of various lengths and rigidity and using different sites of attachments, while maintaining a compact size (<15 kDa). Tumor targeted CD137 agonists were generated as heterotandems, whereby BCY3814 is conjugated to a tumor antigen targeting Bicycle. In this design, the CD137 Bicycle only induces CD137 agonism after the molecule binds to a tumor cell with high receptor expression.
We discovered Bicycle multimers that exhibit a range of potencies in a cell-based CD137-dependent reporter assay, activate human T cells in vitro as indicated by increased cytokine release, and show biological activity in vivo. Bicycle heterotandems targeting Nectin-4 and EphA2 exhibited highly potent and tumor cell specific activity in both the cell-based reporter assay and the human T cell assay. Selected CD137 multimers and heterotandems are being tested further in humanized mouse models for T cell activation, anti-tumor activity, and liver safety. These molecules are promising, novel cancer immunotherapy candidates and importantly, they pave the way for development of synthetic agonists of other TNF receptors that can be targeted to the local tumor microenvironment.
Citation Format: Kristen E. Hurov, Punit Upadhyaya, Jessica Kublin, Xueyuan Zhou, Julia Kristensson, Rachid Lani, Gemma Mudd, Katerine van Rietschoten, Frank An, Johanna Lahdenranta, Liuhong Chen, Gavin Bennett, Kevin McDonnell, Peter Park, Nicholas Keen. Activation of CD137 using multivalent and tumor targeted Bicyclic peptides [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 3257.
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Stuart DD, Shao W, Mishina Y, Feng Y, Caponigro G, Cooke VG, Rivera S, Shen F, Korn J, Griner LAM, Nishiguchi G, Taft B, Wan L, Subramanian S, Lou Y, Setti L, Burger M, Tamez V, Rico A, Aversa R, Tellew J, Haling JR, Polyakov V, Lambert A, Zang R, Abbema AV, Hekmat-Nejad M, Amiri P, Singh M, Keen N, Dillon MP, Lees E, Sellers WR, Ramurthy S. Abstract DDT01-04: Pharmacological profile and anti-tumor properties of LXH254, a highly selective RAF kinase inhibitor. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-ddt01-04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The mitogen-activated protein kinase (MAPK) signaling pathway is frequently activated in human cancers due to genetic alterations that can occur at multiple nodes, the most prevalent of which are mutations in RAS or BRAF. While BRAFV600 mutant tumors are responsive to RAF inhibitors such as dabrafenib and vemurafenib, these drugs are ineffective in RAS mutant cancers and tumors expressing other RAF mutations. CRAF kinase functions as a critical effector in mutant RAS and Class II/III BRAF mutant tumors and plays a role in feedback-mediated pathway reactivation following MEK inhibition. Thus, selective inhibitors that potently inhibit the activity of CRAF could be both effective in blocking mutant RAS and BRAF signaling and in inhibiting feedback-mediated activation in combination with a MEK inhibitor. LXH254 is a type II ATP-competitive inhibitor that inhibits both B- and CRAF kinase activities at picomolar concentrations with a high degree of selectivity against a panel of 456 human kinases and in cell-based assays. LXH254 not only inhibits MAPK signaling activity in tumor models harboring BRAFV600 mutation, but also inhibits mutant N- and KRAS-driven signaling due to its ability to inhibit both RAF monomers and dimers with similar potencies. LXH254 is orally bioavailable, demonstrates a direct PK/PD relationship and causes tumor regression in multiple cell line and primary human tumor derived xenograft models at well-tolerated doses. LXH254 represents a next generation RAF inhibitor that is differentiated from other RAF inhibitors in this class due to the high degree of selectivity. In preclinical efficacy and toxicology studies, LXH254 demonstrated a relatively wide therapeutic index which should enable effective interrogation of RAF inhibition in patients with decreased risk for off-target toxicity. LXH254 is currently in a Phase I trial in patients with solid tumors expressing MAPK pathway mutations.
Citation Format: Darrin D. Stuart, Wenlin Shao, Yuji Mishina, Yun Feng, Giordano Caponigro, Vesselina G. Cooke, Stacey Rivera, Fang Shen, Joshua Korn, Lesley A. Mathews Griner, Giselle Nishiguchi, Benjamin Taft, Lifeng Wan, Sharadha Subramanian, Yan Lou, Lina Setti, Matthew Burger, Victor Tamez, Alice Rico, Robert Aversa, John Tellew, Jacob R. Haling, Valery Polyakov, Amy Lambert, Richard Zang, Ann Van Abbema, Mohamad Hekmat-Nejad, Payman Amiri, Mallika Singh, Nicholas Keen, Michael P. Dillon, Emma Lees, William R. Sellers, Savithri Ramurthy. Pharmacological profile and anti-tumor properties of LXH254, a highly selective RAF kinase inhibitor [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 DDT01-04.
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Bennett G, Huxley P, Brown A, Mudd G, Rietschoten KV, Pavan S, Chen L, Watcham SM, Park PU, Keen N. Abstract 5855: Bicycle Drug Conjugates targeting EphA2 for the treatment of solid tumors: Discovery and selection of BT5528. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-5855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Ephrin receptor A2 (EphA2) is a member of the Ephrin receptor family of cell-cell junction proteins and is both highly overexpressed in several solid tumors and associated with poor prognosis in patients. Bicycles® are novel therapeutic agents: bicyclic peptides constrained via a chemical scaffold, which confer structural stability leading to high affinity and selectivity usually associated with antibodies. Bicycles can be elaborated to carry payloads to a specific target and their relatively small size (1.5-3 kDa) allows rapid tissue penetration and extravasation. Bicycle binders for EphA2 were identified using a proprietary phage display peptide technology consisting of highly diverse phage libraries of Bicycles. Initial screening identified Bicycle binders with high affinity for EphA2. EphA2 binding Bicycles were conjugated to cytotoxic payload via a cleavable linker to form a Bicycle Toxin Conjugate (BTC) and evaluated for EphA2 dependent cytotoxicity in vitro and in vivo. Efficacy was seen in EphA2-expressing xenograft models, but toxicity was seen at higher doses. These Bicycles were highly plasma protein bound, and relatively lipophilic. Visualization of Bicycle distribution by microPET showed localization to tumor, but with significant distribution to liver. Subsequent screening with a wider range of phage libraries and scaffolds identified Bicycle binders with alternate structures, lower PPB and lipophilicity. Crystal structures of these Bicycles bound to EphA2 enabled rational design to enhance potency and drug-like properties. Visualization of bio-distribution of these optimised Bicycles by microPET showed localization to tumor, with negligible localization to liver and renal clearance. A range of Bicycle Toxin Conjugates were produced by linking bicycle binders to cleavable linkers and toxin payloads. A series of BTCs were developed with DM1 payload, with linkers ranging from uncleavable to unhindered disulfide. Similarly, a series of BTCs were developed with MMAE payload, using uncleavable linker and a variety of cleavable peptidic linkers with different enzyme sensitivity. Binding affinity is maintained to EphA2 protein and cells expressing EphA2. BTC efficacy was evaluated in EphA2-expressing xenograft models, initially the HT-1080 fibrosarcoma model, but also MDA-MB-231 triple-negative breast cancer and NCI-H1975 lung cancer models. Efficacy was seen from 1mg/kg qw and complete regression of tumors from 2 weeks dosing at 2mg/kg qw. No efficacy was seen in xenograft models without EphA2 expression (eg MOLP-8).From >75 BTCs evaluated, BT5528 was chosen as a candidate molecule to progress to in-depth preclinical profiling. The development of Bicycle Toxin Conjugates against EphA2 allows fast and efficient targeting of solid tumors while sparing non-tumor tissues.
Citation Format: Gavin Bennett, Philip Huxley, Amy Brown, Gemma Mudd, Katerine van Rietschoten, Silvia Pavan, Liuhong Chen, Sophie M. Watcham, Peter U. Park, Nicholas Keen. Bicycle Drug Conjugates targeting EphA2 for the treatment of solid tumors: Discovery and selection of BT5528 [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 5855.
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Park PU, Lani R, Mudd G, Kristensson J, Rietschoten KV, An WF, Bennett G, McDonnell K, Keen N. Abstract 3756: Small synthetic, multivalent bicyclic peptides that activate T cell costimulatory protein CD137. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-3756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
CD137 (4-1BB/TNFRSF9) belongs to the TNF receptor superfamily and provides costimulatory signaling for T cells and NK cells. Agonistic anti-CD137 antibodies have shown potent, often curative anti-tumor activity in preclinical models. These effects are mainly mediated by cytotoxic T cells and generate long lasting, memory responses. Two human anti-CD137 antibodies urelumab and utomilumab are currently undergoing clinical testing. Urelumab has shown several single-agent, partial responses, but its use has been hampered by hepatoxicity, whilst utomilumab lacks hepatotoxicity, but it has shown little or no single agent activity.
Bicycles® are a new class of drugs - fully synthetic, constrained bicyclic peptides that have antibody-like, high affinity and exquisite target specificity unachievable with conventional small molecule approaches. The Bicycle platform uses phage display and chemical optimization to rapidly identify and mature binders for affinity and physicochemical properties. Their small size (1.5-2 kDa) delivers advantages in tumor penetration, and rapid renal elimination may avoid the liver and GI toxicity often associated with other drug modalities, including certain antibodies. We hypothesized that a fully synthetic Bicycle CD137 agonist with rapid renal clearance, minimal liver interaction and no Fc receptor interaction may induce CD137 mediated anti-tumor activity while avoiding liver toxicity.
1015 Bicycles were screened on phage against recombinant CD137. After phage and chemical optimization, a high affinity lead BCY3814 (KD ~30 nM) was selected. BCY3814 competes for binding with the CD137 ligand and utomilumab (known to bind to CD137 ligand binding site) but does not compete with urelumab which binds an alternative epitope. In common with many TNF receptors, CD137 activation requires receptor crosslinking, thus multivalent binders would be expected to recapitulate the action of its natural trimeric ligand. Uniquely, the versatility of the Bicycle format allowed us to rapidly generate more than 50 different bi-, tri- and tetra-valent variants of BCY3814 with chemical linkers and hinges of various lengths and rigidity using different sites of attachments, while maintaining a compact size (<15 kDa). We developed molecules exhibiting a wide range of potency and efficacy in cell-based CD137 activation assays. Several of these synthetic Bicycle CD137 agonists were 10-fold more potent than the clinical antibodies or the natural ligand. These potent Bicycles are being tested in a humanized CD137 mouse model to demonstrate anti-tumour activity with reduced liver toxicity. We hypothesise that such molecules will be promising, novel cancer immunotherapy candidates and pave the way for development of synthetic agonists of other TNF receptors.
Citation Format: Peter U. Park, Rachid Lani, Gemma Mudd, Julia Kristensson, Katerine Van Rietschoten, W. Frank An, Gavin Bennett, Kevin McDonnell, Nicholas Keen. Small synthetic, multivalent bicyclic peptides that activate T cell costimulatory protein CD137 [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 3756.
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Shao W, Mishina YM, Feng Y, Caponigro G, Cooke VG, Rivera S, Wang Y, Shen F, Korn JM, Mathews Griner LA, Nishiguchi G, Rico A, Tellew J, Haling JR, Aversa R, Polyakov V, Zang R, Hekmat-Nejad M, Amiri P, Singh M, Keen N, Dillon MP, Lees E, Ramurthy S, Sellers WR, Stuart DD. Antitumor Properties of RAF709, a Highly Selective and Potent Inhibitor of RAF Kinase Dimers, in Tumors Driven by Mutant RAS or BRAF. Cancer Res 2018; 78:1537-1548. [PMID: 29343524 DOI: 10.1158/0008-5472.can-17-2033] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 11/22/2017] [Accepted: 01/11/2018] [Indexed: 11/16/2022]
Abstract
Resistance to the RAF inhibitor vemurafenib arises commonly in melanomas driven by the activated BRAF oncogene. Here, we report antitumor properties of RAF709, a novel ATP-competitive kinase inhibitor with high potency and selectivity against RAF kinases. RAF709 exhibited a mode of RAF inhibition distinct from RAF monomer inhibitors such as vemurafenib, showing equal activity against both RAF monomers and dimers. As a result, RAF709 inhibited MAPK signaling activity in tumor models harboring either BRAFV600 alterations or mutant N- and KRAS-driven signaling, with minimal paradoxical activation of wild-type RAF. In cell lines and murine xenograft models, RAF709 demonstrated selective antitumor activity in tumor cells harboring BRAF or RAS mutations compared with cells with wild-type BRAF and RAS genes. RAF709 demonstrated a direct pharmacokinetic/pharmacodynamic relationship in in vivo tumor models harboring KRAS mutation. Furthermore, RAF709 elicited regression of primary human tumor-derived xenograft models with BRAF, NRAS, or KRAS mutations with excellent tolerability. Our results support further development of inhibitors like RAF709, which represents a next-generation RAF inhibitor with unique biochemical and cellular properties that enables antitumor activities in RAS-mutant tumors.Significance: In an effort to develop RAF inhibitors with the appropriate pharmacological properties to treat RAS mutant tumors, RAF709, a compound with potency, selectivity, and in vivo properties, was developed that will allow preclinical therapeutic hypothesis testing, but also provide an excellent probe to further unravel the complexities of RAF kinase signaling. Cancer Res; 78(6); 1537-48. ©2018 AACR.
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