Author Manuscript Published OnlineFirst on November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Research Article AMG 757, a Half-Life Extended, DLL3-Targeted Bispecific T-Cell Engager, Shows High Potency and Sensitivity in Preclinical Models of Small Cell Lung Cancer Michael J. Giffin,1* Keegan Cooke,1* Edward K. Lobenhofer,2 Juan Estrada,1 Jinghui Zhan,1 Petra Deegen,3 Melissa Thomas,4 Christopher M. Murawsky,5 Jonathan Werner,2 Siyuan Liu,1 Fei Lee,6 Oliver Homann,7 Matthias Friedrich,3 Joshua T. Pearson,8 Tobias Raum,9 Yajing Yang,1 Sean Caenepeel,1 Jennitte Stevens,10 Pedro J. Beltran,1 Jude Canon,1 Angela Coxon,1 Julie M. Bailis,6 Paul E. Hughes1 1Oncology Research, Amgen Research, Thousand Oaks, CA, USA; 2Translational Safety & Bioanalytical Sciences, Amgen Research, Thousand Oaks, CA, USA; 3Translational Safety & Bioanalytical Sciences, Amgen Research (Munich) GmbH, Munich, Germany; 4Therapeutic Discovery, Amgen Research, South San Francisco, CA; 5Therapeutic Discovery, Amgen Research, Burnaby, BC, Canada; 6Oncology Research, Amgen Research, South San Francisco, CA, USA; 7Genome Analysis Unit, Amgen Research, South San Francisco, CA, USA; 8Pharmacokinetics & Drug Metabolism, Amgen Research, South San Francisco, CA, USA; 9Therapeutic Discovery, Amgen Research (Munich) GmbH, Munich, Germany; 10Therapeutic Discovery, Amgen Research, Thousand Oaks, CA, USA *Contributed equally to this work. Current address for Michael J. Giffin is Process Development, Amgen Inc., Thousand Oaks, CA, USA. Current address for Joshua T. Pearson is Pharmacodynamics, Pharmacokinetics, and Drug, Merck Research Labs, South San Francisco, CA, USA. Current address for Pedro J. Beltran is Discovery Biology, UNITY Biotechnology, South San Francisco, CA, USA Correspondence: Paul E. Hughes, Amgen Research, One Amgen Center Drive, Thousand Oaks, CA, USA 91320-1799; Tel: 1-805-447-1137; Email: [email protected]; Julie M. Bailis, Amgen Research, 1120 Veterans Blvd, South San Francisco, CA, USA 94080; Tel: 1-650-244-2361; Email: [email protected] Running title: AMG 757 in Preclinical Models of Small Cell Lung Cancer Keywords: SCLC, AMG 757, BiTE®, orthotopic model, DLL3 Financial support: This work was supported by Amgen Inc. Conflicts of interest: MJG, KC, EKL, JE, JZ, MT, CMM, JW, SL, FL, OH, JTP, YY, SC, JS, PJB, JC, AC, JMB, and PEH are or were employees of and own stock in Amgen Inc. PD, MF, and TR are employees of and own stock in Amgen Research (Munich) GmbH. Word count: 4999 (limit, 5000) 1 Downloaded from clincancerres.aacrjournals.org on September 23, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Figures: 6 (limit 6) Supplementary Files: 4 (limit, 8) References: 50 (limit, 50) 2 Downloaded from clincancerres.aacrjournals.org on September 23, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 1 Abstract 2 Purpose: Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor with a high 3 relapse rate, limited therapeutic options, and poor prognosis. We investigated the antitumor 4 activity of AMG 757, a half-life extended bispecific T-cell engager molecule targeting delta-like 5 ligand 3 (DLL3) — a target that is selectively expressed in SCLC tumors but with minimal 6 normal tissue expression. 7 Methods: AMG 757 efficacy was evaluated in SCLC cell lines and in orthotopic and patient- 8 derived xenograft (PDX) mouse SCLC models. Following AMG 757 administration, changes in 9 tumor volume, pharmacodynamic changes in tumor-infiltrating T cells (TILs), and the spatial 10 relationship between the appearance of TILs and tumor histology were examined. Tolerability 11 was assessed in nonhuman primates (NHP). 12 Results: AMG 757 showed potent and specific killing of even those SCLC cell lines with very 13 low DLL3 expression (< 1000 molecules per cell). AMG 757 effectively engaged systemically 14 administered human T cells, induced T cell activation, and redirected T cells to lyse tumor cells 15 to promote significant tumor regression and complete responses in PDX models of SCLC and in 16 orthotopic models of established primary lung SCLC and metastatic liver lesions. AMG 757 was 17 well tolerated with no AMG 757-related adverse findings up to the highest tested dose (4.5 18 mg/kg weekly) in NHP. AMG 757 exhibits an extended half-life in NHP which is projected to 19 enable intermittent administration in patients. 20 Conclusions: AMG 757 has a compelling safety and efficacy profile in preclinical studies 21 making it a viable option for targeting DLL3-expressing SCLC tumors in the clinical setting. 22 Abstract word count: 249/250 3 Downloaded from clincancerres.aacrjournals.org on September 23, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 1 Translational Relevance 2 Small cell lung cancer (SCLC) is an aggressive neuroendocrine malignancy that is associated 3 with a high relapse rate and dismal prognosis. Recent immunotherapeutic approaches using 4 immune checkpoint inhibitors have only modestly improved clinical outcomes. AMG 757 is a 5 first-in-class, half-life-extended bispecific T-cell engager that redirects T cells to specifically kill 6 DLL3-expressing tumor cells. In biologically relevant orthotopic and patient-derived xenograft 7 SCLC disease models, AMG 757 promoted significant tumor regression and complete antitumor 8 responses against established tumors. The antitumor effect of AMG 757 is linked to its ability to 9 promote intratumoral infiltration of activated T cells and facilitate T-cell mediated killing of DLL3- 10 expressing SCLC tumors. This, together with its acceptable nonclinical safety profile, suggest 11 that AMG 757 may be a promising novel option for SCLC therapy. AMG 757 is currently under 12 evaluation in a phase 1 clinical study (NCT03319940) for patients with SCLC. 13 Word count: 142/150 14 4 Downloaded from clincancerres.aacrjournals.org on September 23, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 1 Introduction 2 Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor prone to early 3 metastasis, accounting for 10%–15% of all lung cancers (1-3) and associated with poor 5-year 4 survival (4). Disease relapse and resistance to therapy are common following an initial response 5 to etoposide and platinum-based chemotherapy with or without radiation therapy (5). Immune 6 checkpoint blockade has increased overall survival (OS) in SCLC despite relatively modest 7 response rates (6-9). The anti-programmed cell death-1 (anti-PD-1) antibodies nivolumab and 8 pembrolizumab received accelerated approval in the United States for the treatment of 9 metastatic SCLC with progression on or after platinum-based chemotherapy and at least one 10 other line of therapy (10,11); however, subsequent studies did not confirm increased OS 11 (12,13). The promise of targeted therapies has also not yet been realized in SCLC; a DLL3- 12 targeted antibody drug conjugate with early evidence of clinical activity demonstrated no benefit 13 in a subsequent phase 3 trial (14). Therapeutic agents with different mechanisms of action are 14 still urgently needed for patients with SCLC. 15 Bispecific T-cell engager (BiTE®) molecules are a clinically validated therapeutic modality that 16 redirect a patient’s T cells to kill tumor cells (15). Blinatumomab, the first BiTE® molecule in 17 clinical development, is approved for the treatment of relapsed/refractory B-cell precursor acute 18 lymphoblastic leukemia (16-18) and also demonstrates efficacy in non-Hodgkin lymphoma (19- 19 21). The BiTE® molecule AMG 420, which targets BCMA, demonstrated a 70% response rate in 20 multiple myeloma with 50% minimal residual disease-negative complete responses at the 21 maximum tolerated dose in a phase 1 study (22). In solid tumors, therapeutic index has been a 22 major challenge for the successful development of T cell bispecific antibodies (23,24). 23 Development of AMG 110 (MT110), which targets EpCAM, was discontinued due to on-target, 24 dose-limiting toxicity in the liver and gastrointestinal tract (24). The clinical activity of the CEA- 5 Downloaded from clincancerres.aacrjournals.org on September 23, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 1 targeting T cell bispecific antibody, cibisatamab, is also associated with dose-limiting on-target 2 toxicity in gastrointestinal tissues (23). These data highlight the need to identify therapeutic 3 targets with tumor-specific or tumor-selective expression profiles (23,24). 4 To identify potential BiTE® molecule targets in SCLC, we profiled predicted cell surface proteins 5 for differential expression in a panel of SCLC tumors versus an array of normal tissues and 6 identified the Notch ligand, delta-like ligand 3 (DLL3). DLL3 is expressed during embryonic 7 development (25-28), and together with achaete-scute complex homologue 1, a transcription 8 factor that regulates DLL3 expression, is required for neuroendocrine differentiation and SCLC 9 tumorigenesis (29-31). We generated BiTE® molecules targeting DLL3 to explore T cell- 10 redirected lysis against SCLC tumors.