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

Published OnlineFirst November 17, 2020; DOI: 10.1158/1078-0432.CCR-20-2845

CLINICAL CANCER RESEARCH | TRANSLATIONAL CANCER MECHANISMS AND THERAPY

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 A C Michael J. Gifﬁn1, Keegan Cooke1, Edward K. Lobenhofer2, Juan Estrada1, Jinghui Zhan1, Petra Deegen3, Melissa Thomas4, Christopher M. Murawsky5, Jonathan Werner2, Siyuan Liu1, Fei Lee6, Oliver Homann7, Matthias Friedrich3, Joshua T. Pearson8, Tobias Raum9, Yajing Yang1, Sean Caenepeel1, Jennitte Stevens10, Pedro J. Beltran1, Jude Canon1, Angela Coxon1, Julie M. Bailis6, and Paul E. Hughes1

ABSTRACT ◥ Purpose: Small-cell lung cancer (SCLC) is an aggressive neuro- Results: AMG 757 showed potent and specific killing of even endocrine tumor with a high relapse rate, limited therapeutic those SCLC cell lines with very low DLL3 expression (<1,000 options, and poor prognosis. We investigated the antitumor activity molecules per cell). AMG 757 effectively engaged systemically of AMG 757, a half-life extended bispecific T-cell engager molecule administered human T cells, induced T-cell activation, and redir- targeting delta-like ligand 3 (DLL3)—a target that is selectively ected T cells to lyse tumor cells to promote significant tumor expressed in SCLC tumors, but with minimal normal tissue regression and complete responses in PDX models of SCLC and expression. in orthotopic models of established primary lung SCLC and met- Experimental Design: AMG 757 efficacy was evaluated in SCLC astatic liver lesions. AMG 757 was well tolerated with no AMG 757- cell lines and in orthotopic and patient-derived xenograft (PDX) related adverse findings up to the highest tested dose (4.5 mg/kg mouse SCLC models. Following AMG 757 administration, changes weekly) in NHP. AMG 757 exhibits an extended half-life in NHP, in tumor volume, pharmacodynamic changes in tumor-infiltrating which is projected to enable intermittent administration in patients. T cells (TILs), and the spatial relationship between the appearance Conclusions: AMG 757 has a compelling safety and efficacy of TILs and tumor histology were examined. Tolerability was profile in preclinical studies making it a viable option for targeting assessed in nonhuman primates (NHPs). DLL3-expressing SCLC tumors in the clinical setting.

Introduction Small-cell lung cancer (SCLC) is an aggressive neuroendocrine 1Oncology Research, Amgen Research, Thousand Oaks, California. 2Translational tumor prone to early metastasis, accounting for 10%–15% of all lung Safety & Bioanalytical Sciences, Amgen Research, Thousand Oaks, California. cancers (1–3) and associated with poor 5-year survival (4). Disease 3Translational Safety & Bioanalytical Sciences, Amgen Research (Munich) 4 relapse and resistance to therapy are common following an initial GmbH, Munich, Germany. Therapeutic Discovery, Amgen Research, South San response to etoposide and platinum-based chemotherapy with or Francisco, California. 5Therapeutic Discovery, Amgen Research, Burnaby, British Columbia, Canada. 6Oncology Research, Amgen Research, South San Francisco, without radiotherapy (5). Immune checkpoint blockade has increased California. 7Genome Analysis Unit, Amgen Research, South San Francisco, overall survival (OS) in SCLC despite relatively modest response California. 8Pharmacokinetics & Drug Metabolism, Amgen Research, South San rates (6–9). The anti-programmed cell death-1 (anti–PD-1) antibodies Francisco, California. 9Therapeutic Discovery, Amgen Research (Munich) GmbH, nivolumab and pembrolizumab received accelerated approval in the 10 Munich, Germany. Therapeutic Discovery, Amgen Research, Thousand Oaks, United States for the treatment of metastatic SCLC with progression California. on or after platinum-based chemotherapy and at least one other line of Note: Supplementary data for this article are available at Clinical Cancer therapy (10, 11); however, subsequent studies did not confirm Research Online (http://clincancerres.aacrjournals.org/). increased OS (12, 13). The promise of targeted therapies has also not M.J. Giffin and K. Cooke contributed equally to this article. yet been realized in SCLC; a DLL3-targeted antibody–drug conjugate Current address for Michael J. Giffin, Process Development, Amgen Inc., Thou- with early evidence of clinical activity demonstrated no benefitina sand Oaks, California; current address for Joshua T. Pearson, Pharmacodynam- subsequent phase III trial (14). Therapeutic agents with different ics, Pharmacokinetics, and Drug, Merck Research Labs, South San Francisco, mechanisms of action are still urgently needed for patients with SCLC. California; and current address for Pedro J. Beltran, Discovery Biology, UNITY Bispecific T-cell engager (BiTE) molecules are a clinically validated Biotechnology, South San Francisco, California. therapeutic modality that redirect a patient’s T cells to kill tumor Corresponding Authors: Paul E. Hughes, Amgen Research, One Amgen Center cells (15). Blinatumomab, the first BiTE molecule in clinical develop- Drive, Thousand Oaks, CA 91320–1799. Phone: 805–447–1137; Fax: 805-498- ment, is approved for the treatment of relapsed/refractory B-cell 5666; E-mail: [email protected]; and Julie M. Bailis, Amgen Research, 1120 – – – precursor acute lymphoblastic leukemia (16 18) and also demon- Veterans Blvd, South San Francisco, CA 94080. Phone: 650 244 2361; E-mail: fi – [email protected] strates ef cacy in non-Hodgkin lymphoma (19 21). The BiTE molecule AMG 420, which targets BCMA, demonstrated a 70% response Clin Cancer Res 2020;XX:XX–XX rate in multiple myeloma with 50% minimal residual disease–negative doi: 10.1158/1078-0432.CCR-20-2845 complete responses at the maximum tolerated dose in a phase I study 2020 American Association for Cancer Research. (22). In solid tumors, therapeutic index has been a major challenge for

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Translational Relevance Methods Cell lines Small-cell lung cancer (SCLC) is an aggressive neuroendo- DMS 79, NCI-H2171, NCI-H889, SHP-77, NCI-H211, NCI-H460, crine malignancy that is associated with a high relapse rate and HEK-293, and Chinese hamster ovary (CHO) cell lines were purchas- dismal prognosis. Recent immunotherapeutic approaches using ed from the American Type Culture Collection, NCI-H82 from the immune checkpoint inhibitors have only modestly improved DSMZ-German Collection of Microorganisms and Cell Cultures, and clinical outcomes. AMG 757 is a first-in-class, half-life-extended COR-L279 from Sigma-Aldrich. Cell lines were analyzed for authen- bispecific T-cell engager molecule that redirects T cells to ticity using DNA-fingerprinting techniques such as short tandem specifically kill DLL3-expressing tumor cells. In biologically repeat profiling. All cell lines tested negative for mycoplasma con- relevant orthotopic and patient-derived xenograft SCLC disease tamination. Research Resource Identifiers for cell lines are listed in models, AMG 757 promoted significant tumor regression and Supplementary Tables (Supplementary Table S1). complete antitumor responses against established tumors. The antitumor effect of AMG 757 is linked to its ability to promote intratumoral infiltration of activated T cells and facilitate T-cell– Cell-based assays fi fl mediated killing of DLL3-expressing SCLC tumors. This, together DLL3 expression levels on cell lines were quanti ed in ow cyto- with its acceptable nonclinical safety profile, suggest that AMG 757 metry experiments using standard receptor quantitation methods may be a promising novel option for SCLC therapy. AMG 757 is (QIFIKIT assay [Dako] or Quantum Simply Cellular assay [Bangs currently under evaluation in a phase I clinical study Laboratories]) and analyzed using BD FACSDiva and GraphPad Prism (NCT03319940) for patients with SCLC. or QuickCals software (see Supplementary Methods). Transfected HEK-293 cells were plated at 5,000 cells/well and treated with activated T cells at 50,000 cells/well (10:1 effector to target [E:T] cell ratio) and BiTE molecules at 50 ng/mL final concen- the successful development of T-cell bispecific antibodies (23, 24). tration, titrated 4-fold across the plate (12-point titration curve) in Development of AMG 110 (MT110), which targets EpCAM, was duplicate. After incubation for 20 hours, cell viability was measured discontinued due to on-target, dose-limiting toxicity in the liver and with the Steady-Glo Luciferase assay (Promega). Effector cells (2 105 human or NHP PBMC or isolated human gastrointestinal tract (24). The clinical activity of the CEA-targeting T- þ cell bispecific antibody, cibisatamab, is also associated with dose- CD3 T cells) were cocultured with Vybrant (Thermo Fisher Scien- fi – limiting on-target toxicity in gastrointestinal tissues (23). These data ti c) DiO/Dil labeled target cell lines at an E:T cell ratio of 2:1 or 5:1 fl highlight the need to identify therapeutic targets with tumor-specific and serial dilutions of AMG 757 in 96-well, at-bottom plates. fi or tumor-selective expression profiles (23, 24). Cells were cultured for 48 hours at 37 C in a 5% CO2 humidi ed To identify potential BiTE molecule targets in SCLC, we profiled incubator and washed with FACS buffer. PBMCs were stained with a fluorochrome-labeled anti-CD14 antibody (BD Biosciences) to define predicted cell surface proteins for differential expression in a panel of þ SCLC tumors versus an array of normal tissues and identified the DiO /CD14 target cells (30 minutes; 4 C), washed with FACS buffer, m m Notch ligand, delta-like ligand 3 (DLL3). DLL3 is expressed during and resuspended in 100 L of FACS buffer containing 0.5 g/mL fl embryonic development (25–28), and together with achaete-scute propidium iodide. All ow cytometry experiments were analyzed fl complex homolog 1, a transcription factor that regulates DLL3 expres- using FACSCanto II or LSRFortessa ow cytometers and the fi sion, is required for neuroendocrine differentiation and SCLC BD FACSDiva software (BD Biosciences) and data were tted to a fi – tumorigenesis (29–31). We generated BiTE molecules targeting DLL3 four-parameter nonlinear t model sigmoidal dose response curve fl to explore T-cell–redirected lysis against SCLC tumors. We initially (GraphPad Prism). T-cell activation was evaluated by ow cytometry – evaluated an anti-DLL3 BiTE molecule in the original tandem single- after incubation as described for T-cell dependent cellular cytotoxicity (TDCC) assays. T cells were washed and stained protected from light chain variable fragment (scFv) format (32), which requires administration via continuous intravenous (cIV) infusion due to its short half- for 30 minutes at 4 C for CD4, CD8, and the activation markers CD69, life (33, 34). We then developed AMG 757, a half-life extended (HLE) CD71, PD-1, and PD-L1 using directly conjugated antibodies. For BiTE molecule, by fusing an immunoglobulin G (IgG) crystallizable evaluation of granzyme B and perforin expression, cells stained for fi fi fragment (Fc) domain to the core BiTE molecule structure, which cell surface CD4 and CD8 were xed and permeabilized (Cyto x/ enables longer dosing intervals in patients. Cytoperm, BD Biosciences) and then stained with FITC-conjugated Here, we describe the potent, specific activity of an anti-DLL3 BiTE anti-granzyme B and allophycocyanin-conjugated anti-perforin anti- fl molecule and AMG 757 against SCLC cell lines in vitro, including bodies. Cells were analyzed by ow cytometry. Cytokine levels were high sensitivity for cells with low levels of DLL3 expression (<1,000 analyzed from supernatants of cytotoxicity assays using human DLL3 molecules per cell). We demonstrate that once weekly admin- and NHP Th1/Th2 cytometric bead arrays (BD Biosciences; see istration of AMG 757 drives T-cell activation and expansion in Supplementary Methods). established patient-derived xenograft (PDX) and orthotopic SCLC tumors in mouse models, leading to significant tumor regression Mouse model studies including complete antitumor responses. We report that AMG 757 All research protocols were approved by the Amgen Institu- is well tolerated in nonhuman primate (NHP) toxicology studies tional Animal Care and Use Committee (IACUC) (Study number: with no AMG 757-related adverse findings up to the highest dose 2009–00046). level tested (4.5 mg/kg administered weekly), and that AMG 757 For the admixture xenograft studies, mice were inoculated in exhibits an extended half-life. The potency and sensitivity of AMG 757 the subcutaneous flank with a mixture of 5 106 luciferase-labeled þ in SCLC models, together with favorable nonclinical safety and NCI-H82 or SHP-77 tumor cells and 1 106 human CD3 T cells on pharmacokinetic (PK) profiles, suggests that AMG 757 has potential study day 0. Mice were administered 0.5 mg/kg BiTE molecule by as a DLL3-targeted immune therapy for SCLC. intraperitoneal injection daily from day 1 through day 11. Tumor

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measurements and body weights were collected twice a week through- further evaluated on the basis of literature, predicted extracellular out the study. domain structure, and feasibility of antibody generation. The Notch For the PDX models, female NOD.Cg-Prkdcscid Il2rgtm1Sug/JicTac ligand DLL3, a type I membrane protein expressed primarily during (NOG) mice (Taconic) were implanted subcutaneously with patient- development (31), was prioritized for further evaluation. We contin- derived SCLC tumor fragments (LXFS 1129 and LXFS 538; Charles ued to obtain and analyze comparative data on the DLL3 expression River Laboratories). After an induction period of 41 and 29 days, profile as additional normal tissue samples and updated gene models respectively, when the average tumor volume was 94–123 mm3, mice became available. The final analysis showed that DLL3 RNA was were randomized into two groups and administered activated human detected at fragments per kilobase of transcript per million mapped þ CD3 T cells (2 107) by intravenous infusion on study day 0. Human reads (FPKM) ≥1 in 82% of primary and metastatic SCLC tumors þ CD3 T cells, isolated from PBMCs from two different donors using (maximum FPKM, 116; median, 11.5), and expressed at low levels in negative selection, were purchased from AllCells and activated in vitro the brain, spinal cord, pituitary gland, and testis (FPKM, 1.06–6.55; using IL2 and CD3/CD28/CD2 (STEMCELL Technologies). T-cell Supplementary Fig. S1A). expansion was monitored by cell count, and T-cell activation was Saunders and colleagues first reported identification of DLL3 as a assessed by measuring CD25 expression by flow cytometry. The PDX therapeutic target based on prevalent mRNA expression in SCLC and models used T cells from two different donors, one of which was used large-cell neuroendocrine tumors and limited expression in normal in the admixture xenograft studies. For the PDX efficacy models, mice brain, pancreatic, and esophageal tissues (29). Given prior clinical (n ¼ 9–10/group) were administered 3 mg/kg BiTE molecules by experience with solid tumor BiTE molecule targets, our parallel studies intraperitoneal injection on days 1, 8, and 15. Tumor volumes and had focused on obtaining a detailed understanding of DLL3 protein body weights were measured twice a week until study end at day 23. For expression in normal tissues (Supplementary Table S3). Immuno- pharmacodynamic analysis, mice were administered a single dose of histochemistry (IHC) analysis confirmed DLL3 expression in neurons 3 mg/kg BiTE molecules on day 1 by intraperitoneal injection. At in the human brain (cerebrum, cerebellum, hypothalamus, and hip- 96 hours postdose, tumors were collected and dissociated for analysis pocampus), secretory cells of the human and NHP anterior pituitary of tumor-infiltrating T cells. Additional details are provided in the and the NHP pars intermedia, and human and NHP pancreatic islets, Supplementary Methods. consistent with the mRNA profile. DLL3 staining in these normal Female NOD-scid IL2Rgammanull (NSG) mice (The Jackson Lab- tissues was of weak (1þ) to mild (2þ) intensity and predominantly oratory), 6–7 weeks of age, were inoculated intravenously by tail vein cytoplasmic (Supplementary Fig. S2). The low, mainly cytoplasmic injection with 1 106 SHP-77 Luc cells or 5 104 NCI-H82 Luc cells localization of DLL3 on normal tissues is not expected to be accessible on day 0. On day 7, mice were imaged ventrally and randomized into to BiTE molecule activity. treatment groups (n ¼ 10/group) using the deterministic method In SCLC tumors, 30 of 35 (86%) of samples revealed DLL3 (Studylog Systems, Inc). Each mouse was injected intravenously with expression by immunostaining (Supplementary Fig. S1B), consistent þ 2 107 CD3 human T cells on study day 7, prepared as described with the RNA-seq data (Supplementary Fig. S1A). The DLL3 staining above. BiTE molecules were dosed intraperitoneally once a week for a pattern was homogeneous in both membrane and cytoplasm. Among total of two doses (study days 8 and 15). Bioluminescence imaging the DLL3-positive tumors, staining intensity was weak (1þ)in10 (BLI) quantifications of the ventral lung area and body weights were (28%), mild (2þ) in 14 (40%), and intense (3þ) in 6 (17%) tumors, collected twice a week throughout the study. In the NCI-H82 Luc with > 90% of neoplastic cells staining positive for DLL3 in most model, livers were excised on day 22, and visible metastases were samples. The intensity of immunostaining did not correlate with enumerated using a dissecting microscope. tumor stage, grade, or other clinical factors. DLL3 mRNA and protein For pharmacodynamic analysis of SHP-77 orthotopic tumors, mice were also detected in other solid tumor types, including melanoma and were inoculated with SHP-77 cells as described above and then injected glioblastoma (Supplementary Fig. S3). The prevalent membrane- þ intravenously with 2 107 CD3 human T cells on study day 32. On associated staining of DLL3 in SCLC tumors, together with its low, study day 36, the mice were imaged ventrally and randomized to mainly cytoplasmic expression in a few normal tissues, supported the treatment groups (n ¼ 4/group) and then treated with a single dose of advancement of DLL3 as a target for a BiTE molecule. 3 mg/kg BiTE molecule by intraperitoneal injection. Tumor dissoci- In SCLC cell lines, RNA-seq analysis showed a range of DLL3 ation and analysis are described in Supplementary Methods. expression levels (Supplementary Fig. S1A). Flow cytometry analysis of DLL3 cell surface expression showed generally low levels of DLL3, NHP in vivo pharmacokinetics ranging from approximately 800 DLL3 molecules/cell (NCI-H211) to All research protocols were approved by the Institutional Animal an estimated 3,222 DLL3 molecules/cell (SHP-77) based on quanti- Care and Use Committee (NHP toxicology study number: 121424, tative flow cytometry analysis (Supplementary Table S4). These data NHP PK study number: 121985). PK analysis is described in the were concordant with the DLL3 IHC data (Supplementary Fig. S1C), Supplementary Methods. with intense staining (3þ) of the SHP-77 cell line and weak staining A complete list of reagents and their catalog numbers are listed in (1þ) of the NCI-H211 cell line. DLL3 mRNA and protein were not Supplementary Tables (Supplementary Table S2). detected in the NSCLC cell line NCI-H460, a tumor type where DLL3 expression has not been reported. Collectively, these studies estab- Results lished that DLL3 expression in SCLC cell lines and tumors are similar. DLL3 is an optimal BiTE molecule target We used RNA sequencing (RNA-seq) to profile 28 SCLC primary Anti-DLL3 BiTE molecule binding and activity in vitro and metastatic tumor samples, and approximately 250 normal tissue We generated an anti-DLL3 BiTE molecule for proof of concept samples representing an extensive panel of tissues, to identify potential (Fig. 1A). This anti-DLL3 BiTE molecule had high binding affinity for targets with differential tumor expression using gene-ranking heur- human and NHP DLL3 and CD3, with equilibrium dissociation istics that prioritized target prevalence in tumors and minimal expres- constants (KD) of 3.0 nmol/L and 3.1 nmol/L for human and NHP sion in essential normal tissues. Genes in the preliminary list were then DLL3, and 4.6 nmol/L and 4.4 nmol/L for human and NHP CD3,

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respectively. The anti-DLL3 BiTE molecule demonstrated potent molecule (P ¼ 0.0001; Fig. 1D). In the NCI-H82 xenograft model, activity in TDCC assays against HEK-293 cells transiently transfected which expresses 1,290 DLL3 molecules per cell, mice treated daily to express DLL3, with a half maximal effective concentration (EC50) with the anti-DLL3 BiTE molecule at 0.5 mg/kg had 75% TGI value of 2.2 pmol/L (Fig. 1B). This activity was DLL3-dependent, as no compared with mice treated with the control molecule (P < 0.0001; cell killing activity was observed against mock-transfected HEK-293 Fig. 1E). Together, these studies indicate that an anti-DLL3 BiTE cells (EC50 > 1 nmol/L; Fig. 1B). The anti-DLL3 BiTE molecule molecule can effectively engage human T cells in xenograft tumors – induced cell killing across SCLC cell lines with EC50 values of 18 to inhibit tumor growth. 203 pmol/L (Fig. 1C). These studies validate the approach of targeting DLL3-expressing target cells with a BiTE molecule. AMG 757 binding and activity in vitro AMG 757 was designed to retain the potency and sensitivity of the Anti-DLL3 BiTE molecule antitumor activity in anti-DLL3 BiTE molecule and to have an increased serum half-life to xenograft models facilitate longer dosing intervals. The extended half-life of AMG 757 The in vivo activity of the anti-DLL3 BiTE molecule was initially results from incorporation of a stable, effector-functionless Fc domain assessed in admixture xenograft models, where SCLC tumor cells at the carboxy terminus of the molecule (Fig. 2A; ref. 36). mixed with human T cells were implanted subcutaneously into The binding affinity of AMG 757 to human and NHP DLL3 was mice. The anti-DLL3 BiTE molecule was administered daily due 0.64 0.05 nmol/L and 0.50 0.01 nmol/L, respectively, and AMG to its short half-life. An anti-Mec14 BiTE molecule (35) was used 757 binding affinity to human and NHP CD3 was 14.9 0.4 nmol/L as a negative control. In the SHP-77 xenograft model, which and 12.0 0.3 nmol/L, respectively (Supplementary Table S5). TDCC expresses 3,222 DLL3 molecules per cell (Supplementary assays demonstrated that the in vitro cell potency of AMG 757 Table S4), mice treated daily with 0.5 mg/kg of the anti-DLL3 against DLL3-positive SCLC cell lines was similar to that of the anti- BiTE molecule showed 89% tumor growth inhibition (TGI) after DLL3 BiTE molecule and specific for DLL3-positive cells, with no 15 days compared with mice treated with the anti-Mec14 BiTE evidence of cytotoxicity againsttheNCI-H460celllinethatdoes

Figure 1. The canonical anti-DLL3 BiTE molecule exhibits DLL3-specific activity in vitro and in vivo. A, Schematic representation of the BiTE molecule format (light blue, anti- DLL3 scFv; green, anti-CD3 scFv). B, Dose–response curves of the anti-DLL3 BiTE molecule against HEK-293 cells transiently transfected with a DLL3-expressing vector (HEK-293/DLL3) or mock-transfected (HEK-293/mock). Cells were cocultivated in duplicate with preactivated human pan-T cells at an E:T cell ratio of 10:1 and a dose range of anti-DLL3 BiTE molecule for 20 hours. Specific cytotoxicity was assessed by flow cytometry. C, Dose–response curves of the anti-DLL3 BiTE molecule against representative luciferase-labeled SCLC cell lines. Cells were cocultivated in duplicate with human pan-T cells at an E:T cell ratio of 10:1 and increasing concentrations of anti-DLL3 BiTE molecule for 48 hours. Specific cytotoxicity was assessed with a luminescence readout. The anti-DLL3 BiTE molecule inhibits growth of SHP-77 tumors (D) and NCI-H82 tumors (E). Tumor cells mixed with human T cells were implanted subcutaneously (day 0) and then treated with either the anti-DLL3 BiTE molecule or a control (nontargeting) Mec14 BiTE molecule daily starting on day 1 of the study. , P ¼ 0.0001; , P < 0.0001. Data shown in C represent mean values and SEM for duplicate samples. Data in D and E represent mean SEM, n ¼ 10 mice/cohort. Data in D and E are representative of two and one independent studies, respectively.

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Figure 2. AMG 757 has potent, specific cytotoxic activity against DLL3-expressing SCLC cell lines in vitro. A, Schematic representation of the HLE BiTE format (light blue, anti- DLL3 scFv; green, anti-CD3 scFv; dark blue, Fc domain). B, AMG 757 has similar activity in vitro as the anti-DLL3 BiTE molecule. BiTE molecules were incubated with human pan-T cells and DLL3-positive SHP-77 cells or DLL3-negative NCI-H460 cells at a 10:1 E:T cell ratio, and cell viability was assessed by a luciferase readout after 48 hours. C, Dose–response curves of AMG 757 against representative SCLC cell lines. Cells were cocultivated with human PBMC from multiple human donors at an E:T cell ratio of 5:1 and a dose range of AMG 757 for 48 hours. Target cell lysis was assessed by flow cytometry. D, Cross-reactivity of AMG 757 with NHP effector cells. AMG 757 was incubated with NHP PBMCs (cyPBMC #F1, #F2, #F5, and #F6) and human SCLC target cells at a 5:1 E:T cell ratio for 48 hours. Cell viability was assessed by flow cytometry. The mean values and SEM for duplicate samples are shown in B–D. not express DLL3 (Fig. 2B). AMG 757 effectively engaged human redirected lysis was accompanied a production of proinflammatory T cells to kill SCLC cell lines, including those with very low DLL3 cytokines (Fig. 3C). DLL3 cell surface expression on the corresponding expression levels (<1,000 molecules/cell; Fig. 2C; Supplementary human tumor cell lines is shown in Fig. 3D and in Supplementary Table S4). AMG 757 induced potent cell killing with either human Table S4. Together, these data demonstrate the AMG 757 mechanism or NHP effector cells, with EC50 values within 1- to 7-fold for each of action. cell line, confirming the cross-reactivity of AMG 757 with NHP CD3 (Fig. 2D; Supplementary Table S5). Anti-DLL3 BiTE molecules are well tolerated in NHP AMG 757-dependent cytotoxicity was associated with hallmarks of The cross-reactivity of the anti-DLL3 BiTE molecule and AMG 757 BiTE molecule target engagement, including T-cell activation, cyto- with NHP DLL3 and CD3 established NHP as a relevant model for kine production, and release of cytotoxic granules (Fig. 3). AMG 757 evaluation of the tolerability of these molecules in vivo. The anti-DLL3 increased granzyme B levels and cytotoxicity over time, with maximal BiTE molecule was evaluated in an exploratory, step-dose, nontermi- signal observed at 48 hours (Fig. 3A). Markers of T-cell activation or nal safety study in NHP. Animals received the anti-DLL3 BiTE inflammation, CD69, CD71, PD-1, and PD-L1 (37–39) were upregu- molecule by cIV infusion at doses up to 100 mg/day for 7 days. All lated following AMG 757 treatment (Fig. 3B). AMG 757-mediated doses evaluated were well tolerated, consistent with the idea that the

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Figure 3. AMG 757 activates T cells and promotes cytokine production and T-cell–redirected lysis. A, Granzyme B activation and cytotoxicity of AMG 757 against the SHP-77 cell line cocultivated with human PBMCs at time points from 4 to 72 hours (E:T, 2:1). B, AMG 757-induced expression of activation markers on human T cells. SHP-77 cells were cocultivated with puriﬁed human CD3þ T cells at an E:T cell ratio of 5:1 with a dose range of AMG 757 for 48 hours. T-cell activation was evaluated by ﬂow cytometry. C, AMG 757-induced cytokine release by human PBMCs. Human PBMCs (n ¼ 2) were cocultivated with NCI-H2171, NCI-H889, and SHP-77 tumor cells at an E:T cell ratio of 5:1 and a dose range of AMG 757 concentrations for 48 hours. Levels of cytokines in the cell culture supernatants were measured with the human CBA Th1/Th2 II kit (Becton Dickinson). D, Flow cytometry analysis of DLL3 expression in NCI-2171, NCI-H889, and SHP-77 cell lines. Unstained, cells that were not stained with any antibody; 2nd Ab, cells stained with secondary antibody (anti-mouse FITC) only; DLL3, cells stained with primary DLL3 antibody and secondary anti-mouse FITC antibody.

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and LXFS 538 PDX models of SCLC, which express DLL3 at levels similar to that of NCI-H82 cells (Supplementary Fig. S5A and S5B). Immunocompromised mice bearing established LXFS 1129 tumors received a single administration of human T cells and were then treated with AMG 757 once weekly for 3 weeks. AMG 757 treatment led to 83% tumor regression, including complete responses in eight of 10 mice by day 23, and an overall significant reduction in tumor volume compared with that in mice which received a control HLE BiTE molecule (P < 0.0001; Fig. 5A). In the LXFS 538 model, AMG 757 treatment induced 98% tumor regression, including complete responses in eight of 10 mice by day 21, and an overall significant reduction in tumor volume compared with that in mice which received the control HLE BiTE molecule (P < 0.0001; Fig. 5B). The mice in the LXFS 538 study treated with AMG 757 were observed through day 32 (17 days after the last AMG 757 dose), at which point nine of 10 mice had complete responses, with one mouse having a residual (<5mm3) mass that had remained static for 2 weeks. At this last time point, both the human T cells and AMG 757 would have been cleared from circulation. We developed orthotopic SCLC models to further explore AMG 757 antitumor activity. These models recapitulate the biologic compart- Figure 4. ment of primary SCLC tumors and, like the PDX model, require that AMG 757 exhibits an extended serum half-life. The PK profile of a single 12 mg/kg human T cells administered systemically traffic to the tumor site for intravenous bolus infusion of AMG 757 was analyzed in NHP. AMG 757 serum concentrations at the time points indicated were measured by an immunoassay BiTE molecule target engagement. Consistent with primary SCLC measuring total levels of AMG 757 and were interpolated from a standard curve. tumors, the SHP-77 orthotopic model is characterized by tumor growth in the lungs but the lesions are not visible macroscopically. In contrast, the NCI-H82 orthotopic model mimics SCLC metastatic low level, cytoplasmic DLL3 expression in normal NHP tissues is disease with discrete, visible tumors primarily in the liver. Both models inaccessible to BiTE molecule binding. used cell lines engineered to express luciferase to enable visualization of The PK profile of AMG 757 in NHP was characterized in a single- tumor burden by BLI. Human T cells were administered once, and dose study. After a single 12 mg/kg dose of AMG 757, serum con- BiTE molecules were administered weekly by intravenous infusion to centrations of AMG 757 decreased in a biphasic manner, with a mean immunocompromised mice bearing established orthotopic tumors. clearance of 0.487 mL/hour/kg and a steady-state volume of distri- AMG 757 treatment significantly inhibited growth of established bution of 146 mL/kg (Fig. 4). The maximum serum concentration was orthotopic SHP-77 lung tumors (P < 0.0008; Fig. 5C and D). BLI 0.239 mg/mL and the area under the concentration–time curve was imaging on day 22 revealed that mice treated with AMG 757 exhibited 16.7 hours mg/mL. The trough exposure level after 336 hours significant TGI (Fig. 5D). The minimal BLI signal that persisted in (14 days) was approximately 10-fold higher than the mean in vitro the AMG 757-treated mice at the end of the study might reflect EC50 of AMG 757 across SCLC cell lines. The mean half-life of AMG residual nodules or cell debris. Tumors in mice treated with vehicle 757 was 234 hours (9.8 days). These data confirm that AMG 757 has an alone or with a control HLE BiTE molecule continued to grow extended half-life relative to the anti-DLL3 BiTE molecule. (Fig. 5C and D). In the NCI-H82 orthotopic liver model, AMG 757 AMG 757 was assessed in a 1-month repeat dose toxicology study in treatment significantly inhibited growth of liver metastases com- NHP. Weekly doses of AMG 757 up to 4.5 mg/kg were well tolerated pared with vehicle or control HLE BiTE molecule–treated groups at and no AMG 757-related adverse findings were observed (40). Taken day 22 (P < 0.0001; Fig. 5E). BLI imaging on day 22 revealed a together, the NHP studies suggest that AMG 757 has the potential to marked decrease in tumor mass after AMG 757 treatment (Fig. 5F). achieve high exposures that may be required for effective antitumor Strikingly, no lesions were visible in the liver at day 23 following activity in the clinic. AMG 757 treatment, suggesting complete response to treatment (Fig. 5G and H). In contrast, the vehicle and control HLE BiTE Anti-DLL3 BiTE molecules drive tumor regression in mouse molecule–treated cohorts contained multiple liver lesions (mean of models of SCLC 41.5 and 41.8 lesions, respectively; P < 0.0001; Fig. 5G and H). To demonstrate proof of concept of AMG 757 in vivo, we evaluated antitumor activity in an admixture WM266-4 xenograft model, where AMG 757 engages tumor-infiltrating T cells human T cells and WM266-4 tumor cells were mixed and implanted The pharmacodynamic effects of AMG 757 treatment on T cells subcutaneously in immunodeficient mice. Administration of AMG 757 infiltrating SCLC tumors was evaluated. In the LXFS 538 PDX model, at 0.1, 0.5, or 3 mg/kg every 5 days significantly inhibited tumor we used flow cytometry to assess T-cell numbers and markers of growth in this model (Supplementary Fig. S4). We next used PDX activation from T cells isolated from disaggregated tumor tissue. models to assess the activity of AMG 757 against established SCLC A single dose of AMG 757 led to a statistically significant increase þ þ tumors. PDX tumors replicate the heterogeneity and architecture of in the absolute number of human CD4 and CD8 T cells in human tumors in a mouse model (41), and systemic administration of the tumors at 4 days posttreatment compared with treatment with þ human T cells to mice bearing PDX tumors enables assessment of the control HLE BiTE molecule (CD4 , mean 77,098 vs. 1,601 cells; þ T-cell–mediated antitumor activity, as AMG 757 does not cross react P ¼ 0.004; CD8 , mean 263,289 vs. 2,686 cells; P ¼ 0.012; Fig. 6A). The with mouse CD3. We evaluated AMG 757 activity in the LXFS 1129 T-cell activation markers CD25, CD69, and PD-1 were significantly

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Figure 5. AMG 757 inhibits growth of established PDX and orthotopic SCLC tumors. A and B, Evaluation of AMG 757 antitumor activity against PDX tumors. NOG mice bearing established patient-derived LXFS 1129 (A) and LXFS 538 (B) SCLC tumors were implanted with human T cells on study day 0 and then treated with 3 mg/kg AMG 757 or control HLE BiTE molecule once weekly for 3 weeks beginning on day 1. , P < 0.0001. C, Evaluation of AMG 757 activity against lung tumors in the SHP-77 orthotopic model. NSG mice were implanted with human T cells on study day 7 and then treated with 3 mg/kg AMG 757 or control HLE BiTE molecule once weekly for 2 weeks beginning on day 8. BLI (photons/second) from a region of interest (ROI) on the upper chest/lung region of the mice is shown. , P < 0.0008. Data are representative of two independent experiments. D, Luminescence images of three representative mice from each group in C at day 7 (pretreatment) and day 22 are shown. E, Evaluation of AMG 757 activity against metastatic liver lesions in the NCI-H82 orthotopic model. BLI (photons/second) from a ROI on the central chest region of each mouse is shown. , P < 0.0001. F, Luminescence images of three representative mice from each group from E at day 7 (pretreatment) and day 22 are shown. G, Photos of three representative livers from each group from E at day 23 are shown. H, The number of visible liver lesions from different treatment groups in E on day 23 of study were compared. , P < 0.0001. Data in A–C and E represent mean SEM, n ¼ 9–10 mice/cohort. Data represent mean SD, n ¼ 10 mice/cohort. Data described in A, B, E,andH were derived from one independent study each. Red arrows in A, B, C,andE indicate AMG 757 or control HLE BiTE molecule or vehicle dosing.

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þ þ upregulated (P < 0.0001) in CD4 and CD8 T cells in the AMG 757- after administration of AMG 757 in metastatic liver lesions from the þ treated group compared with the control HLE BiTE molecule–treated NCI-H82 xenograft SCLC model (CD4 , mean of 1,080 vs. 78.2 cells/ þ group in LXFS 538 PDX tumors (Fig. 6B and C). mg of tumor tissue; P < 0.0001; CD8 , mean of 1,597 vs. 89.6 cells/mg Similarly, in the SHP-77 orthotopic model, a signiﬁcant increase in of tumor tissue; P < 0.0001; Fig. 6E) when compared with the number þ þ human CD4 and CD8 T-cell counts in the disaggregated lung tissue of cells from groups receiving HLE BiTE molecule. occurred 7 days posttreatment with AMG 757 compared with those While a signiﬁcant upregulation of the T-cell activation markers þ from the control HLE BiTE molecule–treated group (CD4 , mean CD25, CD69, PD-1, and 4-1BB was observed on T cells from meta- þ 60 vs. 7.9 cells/mg of lung tissue; P ¼ 0.013; CD8 , mean 117.8 vs. static liver lesions from the AMG 757-treated group in the NCI-H82 16.7 cells/mg of lung tissue; P ¼ 0.018; Fig. 6D), and 72 hours model, this increase was not observed in T cells from the disaggregated

Figure 6. AMG 757 induces T-cell activation and tumor infiltration. A, Evaluation of T-cell infiltration into LXFS 538 PDX tumors 96 hours after treatment with AMG 757 or a control HLE BiTE molecule. , P ¼ 0.012; , P ¼ 0.004. B, Activation of human CD4þ T cells isolated from LXFS 538 PDX tumors 96 hours after treatment with AMG 757 or a control HLE BiTE molecule. , P ¼ 0.001; , P < 0.0005. C, Activation of human CD8þ T cells isolated from LXFS 538 PDX tumors 96 hours after treatment with AMG 757 or a control HLE BiTE molecule. , P ¼ 0.002; , P < 0.0001. D, Evaluation of T-cell infiltration into SHP-77 tumors in lungs 168 hours after treatment with AMG 757 or a control HLE BiTE molecule. , P < 0.05. E, Evaluation of T-cell infiltration into NCI-H82 metastatic liver tumors 72 hours after treatment with AMG 757 or a control HLE BiTE molecule. , P < 0.0001. F, Activation of human CD4þ T cells isolated from mouse livers harboring NCI-H82 tumors 72 hours after treatment with AMG 757 or a control HLE BiTE molecule. , P ¼ 0.001; , P < 0.0001. G, Activation of human CD8þ T cells isolated from mouse livers harboring NCI-H82 tumors 72 hours after treatment with either AMG 757 or a control HLE BiTE molecule. , P < 0.0001 H, Representative photomicrographs of hematoxylin and eosin–stained liver with NCI-H82 orthotopic tumors 72 hours after treatment with AMG 757 or a control HLE BiTE molecule. Magnification is 8 (top left and top right; scale bar ¼ 100 mm) and 40 (bottom left and bottom right; scale bar ¼ 50 mm). T, NCI-H82 tumor; L, normal liver; dotted line, margin between NCI-H82 tumor and normal liver; , tumor periphery with viable and degenerate inflammatory cells, necrotic cellular debris, and collapsed stroma. I, Representative photomicrographs of IHC staining for CD4 and CD8 (as shown by brown staining) in livers with NCI-H82 orthotopic tumors from mice treated with AMG 757 or a control BiTE molecule. Magnification is 8 (scale bar ¼ 100 mm). Data represent mean SD, n ¼ 4–6 mice/cohort. The data described in A–C, H,andI represent a single study and data in D–G represent two independent studies.

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lung tissue from the SHP-77 orthotopic model (Fig. 6F and G; DLL3 expression (45). Despite early clinical activity of rovalpituzumab Supplementary Fig. S6). This may be due to the fact that the total teserine (12%–18% objective response rates; refs. 45, 46), treatment population of lung-resident T cells was analyzed in the SHP-77 was associated with dose-limiting adverse events, including pleural orthotopic model rather than T cells specific to the lung tumors. and pericardial effusion and skin reactions, which limited treatment to NCI-H82 tumors from mice treated with AMG 757 and the two cycles on average (45). These findings were also attributed to PBD, control HLE BiTE molecule were compared to evaluate tumor and development of rovalpituzumab tesirine was halted after a phase morphology and the spatial relationship between infiltrating T III study showed no survival benefit (14). The toxicity profile of cells and tumor cells. In hematoxylin- and eosin–stained sections, rovalpituzumab tesirine in preclinical and clinical studies is, therefore, NCI-H82 tumors treated with AMG 757 had a qualitative increase not associated with DLL3 expression (46). While recent advances in in infiltrating lymphocytes dispersed throughout the tumor and in linker technology, antibody design, and payload optimization may the tumor periphery. While the control HLE BiTE molecule-treated improve the therapeutic index of an ADC targeting DLL3, the rela- tumors were well-demarcated and composed primarily of viable tively low abundance of DLL3 suggests that it could be challenging to neoplastic cells, AMG 757-treated tumors exhibited viable and deliver sufficient amounts of a toxic payload to DLL3-positive SCLC degenerate inflammatory cells, necrotic cellular debris, and col- tumors without dose-limiting toxicity caused by unconjugated pay- lapsed stroma in the periphery (Fig. 6H). IHC demonstrated that load. The combination of activity in preclinical tumor models and þ þ the infiltrating lymphocytes were CD4 and CD8 T cells (Fig. 6I). preliminary safety data in cynomolgus monkeys highlight the promise Collectively, the orthotopic models demonstrate that AMG 757 can of targeting DLL3 with a BiTE molecule. In addition to AMG 757, promote T-cell trafficking to tumors in different compartments and chimeric antigen receptor (CAR)-T cells targeting DLL3 in SCLC and engage T cells to DLL3-expressing SCLC cells, enabling complete other neuroendocrine tumors are in development, and DLL3-targeted antitumor responses against established SCLC tumors. radioimmunoconjugates are also being explored (31, 47). The treatment paradigm in SCLC has recently changed with the approval of PD-1/PD-L1 immune checkpoint inhibitors in multiple Discussion settings, including as part of first-line therapy in combination with AMG 757 is a first-in-class HLE BiTE immuno-oncology therapy chemotherapy (8, 48). Although these approvals represent a significant targeting DLL3 for the treatment of SCLC. Here, we demonstrate that advancement in SCLC treatment, the overall response rates remain AMG 757 engages T cells to induce potent redirected lysis of SCLC low. AMG 757 provides an option for therapeutic targeting of DLL3- cells in vitro and significant antitumor activity in mouse models of expressing SCLC cells by a mechanism that is completely distinct from primary and metastatic SCLC. In vitro, AMG 757 had potent cell that of immune checkpoint inhibitors. AMG 757 demonstrates killing activity against SCLC cells with as low as <1,000 DLL3 receptors engagement of T cells and direct T-cell–mediated killing of established per cell. In vivo, AMG 757 engaged human T cells administered tumors, and also the potential to promote T-cell infiltration into systemically and DLL3-expressing tumor cells to promote tumor tumors. AMG 757 therefore may also be considered for combination regression. In our models, AMG 757 monotherapy cleared established therapy with anti–PD-1/PD-L1 inhibitors in patients where it may tumors including visible metastases, and only residual nodules were enhance the activity of immune checkpoint inhibitors (15, 49); bli- detected even in the LXFS 538 model, where the mice remained on natumomab and other BiTE molecules have been shown to upregulate study 17 days after the last treatment of AMG 757. However, as our the PD-1/PD-L1 axis and patients may benefit from combination tumor models use immunocompromised mice, and the human T cells therapy with immune checkpoint inhibitors (50). AMG 757 provides a administered once at the start of our studies do not persist beyond a few new option for SCLC therapy with a compelling nonclinical safety: weeks, these models are not suitable for the longer-term evaluation efficacy profile, and clinical evaluation in patients with SCLC is necessary to uncover mechanisms of resistance to AMG 757. The ongoing (NCT03319940). impact of DLL3 expression levels and the tumor microenvironment on AMG 757 activity and potential resistance mechanisms will be further Authors’ Disclosures assessed in patients with SCLC. M.J. Giffin reports nonfinancial support from Scott Medical Communications, A 1-month repeat dose NHP toxicology study showed that LLC and Cactus Life Sciences, part of Cactus Communications during the conduct of AMG 757 was well tolerated at 4.5 mg/kg, a dose with exposure levels the study; in addition, M.J. Giffin reports employment and stock ownership in Amgen. K. Cooke is an Amgen employee and owns Amgen stock. E.K. Lobenhofer reports that far exceed the mean in vitro cell EC50 values, with no AMG 757- nonfinancial support from Scott Medical Communications, LLC and Cactus Life related adverse findings. Given the high affinity binding of AMG 757 Sciences, part of Cactus Communications, during the conduct of the study; in to NHP DLL3 and CD3, and the potent activity of NHP effector cells addition, E.K. Lobenhofer reports employment and stock ownership in Amgen, in redirected lysis of SCLC tumor cells, the in vivo safety profile Inc. J.C. Estrada is an Amgen employee and owns Amgen stock. J. Zhan is an Amgen strongly suggests that DLL3 expressed on normal tissues is largely employee and owns Amgen stock. P. Deegen reports nonfinancial support from Scott inaccessible to AMG 757 target engagement. BiTE molecules may Medical Communications, LLC and Cactus Life Sciences, part of Cactus access targets expressed in the brain, as blinatumomab has been Communications, during the conduct of the study; in addition, P. Deegen reports employment and stock ownership in Amgen. M. Thomas reports nonfinancial detected in the brain and can be associated with neurologic events, support from Scott Medical Communications, LLC and Cactus Life Sciences, part and an EGFRvIII-targeting BiTE molecule, AMG 596, is in develop- of Cactus Communications, during the conduct of the study; in addition, M. Thomas ment for glioblastoma (42–44). reports employment and stock ownership in Amgen. C.M. Murawsky reports The safety profile of AMG 757 in NHP is very different from that of nonfinancial support from Scott Medical Communications, LLC and from Cactus another DLL3-targeted therapy, the antibody-drug conjugate (ADC) Life Sciences, part of Cactus Communications, during the conduct of the study; rovalpituzumab tesirine. Safety-related findings in preclinical toxicol- in addition, C.M. Murawsky reports employment and stock ownership in Amgen. J. Werner reports nonfinancial support from Scott Medical Communications and ogy studies with rovalpituzumab tesirine included myelosuppression, Cactus Life Sciences during the conduct of the study; in addition, J. Werner reports kidney degeneration, and thickening and hyperpigmentation of the employment and stock ownership in Amgen. S. Liu reports nonfinancial support from skin (29). These adverse effects were attributed to the cytotoxic payload Scott Medical Communications, LLC and Cactus Life Sciences, part of Cactus of the molecule, pyrrolobenzodiazepine (PBD), and were not related to Communications, during the conduct of the study; in addition, S. Liu reports

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employment and stock ownership in Amgen. F. Lee reports nonfinancial support writing-review and editing. P. Deegen: Formal analysis, supervision, validation, from Scott Medical Communications, LLC during the conduct of the study; and investigation, visualization, methodology, writing-review and editing. M. Thomas: reports employment and stock ownership in Amgen. O. Homann reports Resources, formal analysis, supervision, validation, investigation, methodology, nonfinancial support from Scott Medical Communications, LLC and Cactus Life writing-review and editing. C.M. Murawsky: Resources, data curation, formal Sciences, part of Cactus Communications, during the conduct of the study; analysis, supervision, validation, investigation, methodology, writing-review in addition, O. Homann reports employment and stock ownership in Amgen. and editing. J. Werner: Data curation, validation, investigation, visualization, M. Friedrich reports nonfinancial support from Scott Medical Communications methodology, writing-review and editing. S. Liu: Validation, investigation, and Cactus Life Sciences during the conduct of the study; in addition, M. Friedrich has visualization, methodology, writing-review and editing. F. Lee: Validation, a patent for US20170349668A1 pending; and reports employment and stock investigation, visualization, methodology, writing-review and editing. ownership in Amgen. J.T. Pearson reports nonfinancial support from Scott O. Homann: Conceptualization, data curation, software, formal analysis, Medical Communications, LLC and Cactus Life Sciences during the conduct validation, investigation, visualization, methodology, writing-original draft, of the study; personal fees from Merck & Co outside the submitted work; in writing-review and editing. M. Friedrich: Conceptualization, formal analysis, addition, J.T. Pearson also reports past employment (ending December 3, 2018) validation, investigation, visualization, methodology, writing-review and editing. and stock ownership in Amgen. T. Raum reports nonfinancial support from Scott J.T. Pearson: Formal analysis, validation, investigation, visualization, Medical Communications, LLC and Cactus Communications during the conduct of methodology, writing-original draft, writing-review and editing. T. Raum: Formal the study; in addition, T. Raum has a patent for US20170037130 pending; in addition, analysis, supervision, validation, visualization, methodology, writing-original draft, T. Raum is an Amgen employee and has stock ownership in Amgen. S. Caenepeel writing-review and editing. Y. Yang: Formal analysis, validation, investigation, reports nonfinancial support from Scott Medical Communications, LLC and Cactus visualization, methodology, writing-review and editing. S. Caenepeel: Formal Life Sciences, part of Cactus Communications during the conduct of the study; in analysis, validation, investigation, visualization, methodology, writing-review addition, S. Caenepeel reports employment and stock ownership in Amgen. J. Stevens and editing. J. Stevens: Formal analysis, supervision, validation, visualization, reports nonfinancial support from Scott Medical Communications, LLC during methodology, writing-review and editing. P.J. Beltran: Supervision, writing- the conduct of the study; in addition, J. Stevens reports employment and stock review and editing. J. Canon: Supervision, writing-review and editing. A. Coxon: ownership in Amgen. P.J. Beltran reports nonfinancial support from Scott Medical Conceptualization, supervision, validation, writing-review and editing. J.M. Bailis: Communications and Cactus Communications during the conduct of the study; other Conceptualization, formal analysis, supervision, validation, visualization, from Amgen outside the submitted work. J. Canon reports nonfinancial support from methodology, writing-original draft, writing-review and editing. P.E. Hughes: Scott Medical Communications, LLC and Cactus Life Sciences during the conduct of Conceptualization, resources, formal analysis, supervision, writing-original draft, the study; in addition, J. Canon was an employee and stock holder of Amgen. J.M. writing-review and editing. Bailis reports nonfinancial support from Scott Medical Communications, LLC and Cactus Life Sciences, part of Cactus Communications, during the conduct of the Acknowledgments study; in addition, J.M. Bailis is an employee of Amgen, Inc. and holds stock The results shown here are based, in part, on data generated by the TCGA ownership in Amgen, Inc. P. Hughes reports nonfinancial support from Scott Research Network (https://www.cancer.gov/tcga). The authors acknowledge Medical Communications, LLC and Cactus Life Sciences, part of Cactus Karen Hettwer, Rodolfo Yabut, Roberto Guzman, David Smith, Joachim Wahl, Communications during the conduct of the study; in addition, P. Hughes is a Kathy Manchulenko, Tao Osgood, Melody Richardson, and Amy Gilbert for shareholder and employee of Amgen Inc. No disclosures were reported by the technical support. Medical writing support was provided by Ben Scott, PhD (Scott other authors. Medical Communications, LLC), Sukanya Raghuraman, PhD (Cactus Life Sciences, part of Cactus Communications), Micah Robinson, PhD (Amgen Inc.), Authors’ Contributions and Jacqueline Sayyah (Amgen, Inc.). This study was funded by Amgen Inc. We thankMarkSalvati,PhD,andMarie-AnneDamietteSmit,MD,MS,forcritical fi M.J. Gif n: Conceptualization, formal analysis, supervision, validation, review of the manuscript. investigation, visualization, methodology, writing-original draft, writing-review and editing. K. Cooke: Conceptualization, resources, formal analysis, supervision, The costs of publication of this article were defrayed in part by the payment of page validation, investigation, visualization, methodology, writing-original draft, writing- charges. This article must therefore be hereby marked advertisement in accordance review and editing. E.K. Lobenhofer: Conceptualization, data curation, formal with 18 U.S.C. Section 1734 solely to indicate this fact. analysis, supervision, validation, investigation, visualization, methodology, writing-original draft, writing-review and editing. J. Estrada: Formal analysis, validation, investigation, visualization, methodology, writing-review and editing. Received July 21, 2020; revised October 21, 2020; accepted November 13, 2020; J. Zhan: Formal analysis, validation, investigation, visualization, methodology, published first September 30, 2020.

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OF12 Clin Cancer Res; 2020 CLINICAL CANCER RESEARCH

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, Keegan Cooke, Edward K. Lobenhofer, et al.

Clin Cancer Res Published OnlineFirst November 17, 2020.

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