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Supplemental Figure 2. AMG 232 treatment causes p53 stabilization, and increased p21 and MDM2 proteins in p53 wild-type cells.

Supplemental Figure 3. Body weights of mice in xenograft efficacy studies

Supplemental Figure 1. AMG 232 chemical structure, and 3-D model of AMG 232 bound to MDM2 protein.

Supplementary Figure 2 from Identification of a Novel Recepteur d'Origine Nantais/c-Met Small-Molecule Kinase Inhibitor with Antitumor Activity In vivo

Supplementary Figure 1 from Identification of a Novel Recepteur d'Origine Nantais/c-Met Small-Molecule Kinase Inhibitor with Antitumor Activity In vivo

Recepteur d'origine nantais (RON) is a receptor tyrosine kinase closely related to c-Met. Both receptors are involved in cell proliferation, migration, and invasion, and there is evidence that both are deregulated in cancer. Receptor overexpression has been most frequently described, but other mechanisms can lead to the oncogenic activation of RON and c-Met. They include activating mutations or gene amplification for c-Met and constitutively active splicing variants for RON. We identified a novel inhibitor of RON and c-Met, compound I, and characterized its in vitro and in vivo activities. Compound I selectively and potently inhibited the kinase activity of RON and c-Met with IC50s of 9 and 4 nmol/L, respectively. Compound I inhibited hepatocyte growth factor–mediated and macrophage-stimulating protein–mediated signaling and cell migration in a dose-dependent manner. Compound I was tested in vivo in xenograft models that either were dependent on c-Met or expressed a constitutively active form of RON (RONΔ160 in HT-29). Compound I caused complete tumor growth inhibition in NIH3T3 TPR-Met and U-87 MG xenografts but showed only partial inhibition in HT-29 xenografts. The effect of compound I in HT-29 xenografts is consistent with the expression of the activating b-Raf V600E mutation, which activates the mitogen-activated protein kinase pathway downstream of RON. Importantly, tumor growth inhibition correlated with the inhibition of c-Met–dependent and RON-dependent signaling in tumors. Taken together, our results suggest that a small-molecule dual inhibitor of RON/c-Met has the potential to inhibit tumor growth and could therefore be useful for the treatment of patients with cancers where RON and/or c-Met are activated. [Cancer Res 2008;68(16):6680–7]

Supplementary Figure Legends 1-3 from Identification of a Novel Recepteur d'Origine Nantais/c-Met Small-Molecule Kinase Inhibitor with Antitumor Activity In vivo

Supplementary Figure 3 from Identification of a Novel Recepteur d'Origine Nantais/c-Met Small-Molecule Kinase Inhibitor with Antitumor Activity In vivo

KRAS is the most frequently mutated oncogene in cancer and encodes a key signalling protein in tumours1,2. The KRAS(G12C) mutant has a cysteine residue that has been exploited to design covalent inhibitors that have promising preclinical activity3–5. Here we optimized a series of inhibitors, using novel binding interactions to markedly enhance their potency and selectivity. Our efforts have led to the discovery of AMG 510, which is, to our knowledge, the first KRAS(G12C) inhibitor in clinical development. In preclinical analyses, treatment with AMG 510 led to the regression of KRASG12C tumours and improved the anti-tumour efficacy of chemotherapy and targeted agents. In immune-competent mice, treatment with AMG 510 resulted in a pro-inflammatory tumour microenvironment and produced durable cures alone as well as in combination with immune-checkpoint inhibitors. Cured mice rejected the growth of isogenic KRASG12D tumours, which suggests adaptive immunity against shared antigens. Furthermore, in clinical trials, AMG 510 demonstrated anti-tumour activity in the first dosing cohorts and represents a potentially transformative therapy for patients for whom effective treatments are lacking. Treatment of KRASG12C-mutant cancer cells with the KRAS(G12C) inhibitor AMG 510 leads to durable response in mice, and anti-tumour activity in patients suggests that AMG 510 could be effective in patients for whom treatments are currently lacking.

Background Metastatic castration-resistant prostate cancer (mCRPC) and Ewing sarcoma (EWS) are diseases for which immune therapies could potentially provide benefit. STEAP1 (Six Transmembrane Epithelial Antigen of the Prostate 1) is a cell surface protein with elevated expression in mCRPC 1 and EWS.2 Methods We designed AMG 509, a novel, half-life extended, STEAP1 x CD3 XmAb® 2+1 bispecific antibody to induce T cell-mediated cytotoxicity against STEAP1-expressing cancer cells. AMG 509 contains two identical anti-STEAP1 Fab domains, an anti-CD3 scFv domain, and an effectorless Fc domain that extends serum half-life. We characterized STEAP1 expression in normal and tumor tissues by immunohistochemistry, and we assessed the pharmacological properties of AMG 509 including binding, T cell-mediated redirected lysis, and in vivo antitumor activity. Results We detected high STEAP1 surface expression on 80% of primary prostate tumors (n=88), 89% of mCRPC lesions (n=114), including 84% of mCRPC bone metastases (n=31), and 63% of EWS samples (n=35). In contrast, in normal tissues (n=72), low STEAP1 expression was detected in only six other tissues, including the normal prostate. AMG 509 bound to recombinant human CD3e with a KD of 27.6 nM, and it bound specifically to 293T cells transfected with human STEAP1 with an EC50 of 3.8 nM. AMG 509 triggered potent T cell-redirected lysis of STEAP1-positive cancer cells, with a median EC50 of 37 pM across 19 cancer cell lines that endogenously express various levels of STEAP1. AMG 509-mediated cytotoxicity was specific, as it showed no activity against prostate cancer cells in which STEAP1 was knocked out. AMG 509 was 65-fold more potent in inducing the redirected lysis of prostate cancer cells in vitro than an XmAb® molecule with a single anti-STEAP1 Fab domain. AMG 509 had greater cytotoxic activity against high STEAP1-expressing cancer cells than against low STEAP1-expressing cancer cells, and it had minimal activity against normal cells. This preferential killing of high STEAP1-expressing cells is likely driven by the avidity conferred by the dual STEAP1-binding domains, a feature that may help reduce off-target effects in the clinic. In vivo, AMG 509 induced robust anti-tumor activity in prostate cancer and EWS mouse xenograft models, with concomitant CD8+ T-cell activation and expansion in tumors. Conclusions AMG 509 is a specific, first-in-class T cell-recruiting antibody with avidity-driven activity against STEAP1-positive malignancies. AMG 509 is currently being evaluated for safety, pharmacokinetics, and efficacy in a phase 1, first-in-human study in patients with mCRPC (NCT04221542). Acknowledgements The authors acknowledge Micah Robinson, PhD of Amgen Inc. for medical writing support. Trial Registration ClinicalTrials. gov Identifier: NCT04221542 Ethics Approval All animal experimental protocols were approved by an Institutional Animal Care and Use Committee (IACUC protocol number 2015-01243) and were conducted in accordance with the guidelines of the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC) (Amgen) or the standards of the Public Health Service (PHS) Policy on Humane Care and Use of Laboratory Animals (IACUC protocol number 15015x) in a facility certified with an Office of Laboratory Animal Welfare (OLAW) (UTHSA). References Grunewald TGP, Ranft A, Esposito I, Silva-Buttkus P da, Aichler M, Baumhoer D, Schaefer KL, Ottaviano L, Poremba C, Jundt G, Jurgens H, Dirksen U, Richter GHS, Burdach S. High STEAP1 expression is associated with improved outcome of Ewing’s sarcoma patients. Ann Oncol 2012; 23:2185–2190. Hubert RS, Vivanco I, Chen E, Rastegar S, Leong K, Mitchell SC, Madraswala R, Zhou Y, Kuo J, Raitano AB, Jakobvits A, Saffran SC, Afar DE. STEAP: a prostate-specific cell-surface antigen highly expressed in human prostate tumors. Proc Natl Acad Sci USA 1999;96:14523–14528.

Acute Myeloid Leukemia (AML) is the most common and aggressive acute leukemia in adults, with a 25% 5-year survival rate. FLT3 is the most frequently mutated gene in AML. About 25% of AML patients harbor FLT3 internal tandem duplication (ITD) mutations, and about 8 % of patients harbor FLT3 tyrosine kinase domain (TKD) mutations. Both FLT3-ITD and FLT3-TKD mutations constitutively activate the protein, which causes poor survival. Gilteritinib is a highly potent and selective oral FLT3 inhibitor recently approved by the FDA. Although gilteritinib showed strong single agent activity in AML patients with FLT3 mutations, the development of gilteritinib resistance limits the long-term efficacy of this treatment, indicating that combination therapy may be advantageous for AML patients with FLT3 mutations. FLT3 mutations are known to be anti-apoptotic. Myeloid cell leukemia-1 (MCL-1), an anti-apoptotic protein, expressed in a large percentage of the AML patient population, plays a critical role in AML cell survival and drug resistance. AMG 176 is a potent, selective and orally bioavailable MCL-1 inhibitor, which induces rapid commitment to apoptosis in AML. Here we demonstrated that AMG 176 and gilteritinib combination treatment synergistically targeted FLT3-ITD mutated AML. A strong synergistic effect (Combination index Citation Format: Xiaoyue Chen, Sean Caenepeel, Brian Belmontes, Patricia L. McElroy, Karen Rex, Tao Osgood, Paul Hughes. Efficacy of AMG 176 in combination with gilteritinib in preclinical models of acute myeloid leukemia [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 1050.

KRAS is the most frequently mutated oncogene in cancer and encodes a key signaling protein in tumors. The p.G12C mutation of KRAS is present in approximately 13% of lung adenocarcinoma, 3% of colorectal cancer, and 2% of other solid tumors. Sotorasib (formerly known as AMG 510), the first KRASG12C inhibitor to reach clinical testing in humans, has demonstrated evidence of clinical activity as a single agent in patients with non-small cell lung (NSCLC), colorectal (CRC), endometrial, and appendiceal carcinoma. Preclinically, sotorasib has shown significant tumor growth inhibition as a single agent in multiple CDX and PDX models. The clinically-validated strategy of combining multiple inhibitors in the MAPK pathway suggests that combination strategies could yield even better outcomes for patients. Specifically, the combination of sotorasib and other inhibitors in the MAPK and AKT signaling pathways might further enhance tumor cell killing and overcome potential resistance. To test this hypothesis, in vitro combination experiments were conducted in multiple KRAS p.G12C cell lines with combination matrices of sotorasib and inhibitors of HER kinases, EGFR, SOS1, SHP2, MEK, PI3K, or mTOR, as well as an inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6). The combination of sotorasib with multiple agents resulted in robust synergistic cell killing of KRAS p.G12C tumor cells in vitro. To understand whether these observations translated in vivo, we assessed combinations of sotorasib with a SHP-2 inhibitor or a HER kinase inhibitor in pharmacodynamic assays and efficacy models in tumor xenografts. Consistent with the synergy observed in vitro, sotorasib in combination with a HER kinase inhibitor (afatinib) or a SHP2 inhibitor (RMC-4550) in vivo resulted in enhanced inhibition of MAPK signaling as measured by p-ERK in NCI-H358 tumors. In efficacy studies using the NCI-H358 xenograft model, significantly enhanced anti-tumor activity was observed with a minimally efficacious dose of sotorasib in combination with afatinib, RMC-4550, or a CDK4/6 inhibitor (palbociclib). Furthermore, enhanced anti-tumor activity was observed with sotorasib in combination with a MEK inhibitor or with the anti-EGFR monoclonal antibody panitumumab in a CRC KRAS p.G12C PDX model. Taken together, these data support the clinical evaluation of combination treatment of sotorasib with analogous agents in patients with KRAS p.G12C tumors. Citation Format: Karen Rex, Anne Y. Saiki, Tyler Holt, Alla Verlinsky, Patricia L. McElroy, Tao Osgood, Ji-Rong Sun, Marwan G. Fakih, Upendra P. Dahal, Bernd Bruenner, Victor J. Cee, Brian A. Lanman, Jude Canon, J. Russell Lipford. Combination of the KRASG12C inhibitor sotorasib with targeted agents improves anti-tumor efficacy in KRAS p.G12C cancer 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 1057.

Sotorasib (formerly known as AMG 510), the first-in-class KRASG12C inhibitor, has demonstrated promising clinical efficacy in KRAS p.G12C mutant cancers. Sotorasib binds to KRASG12C through a unique interaction with a surface groove created by side-chain rotation of histidine 95 (His95). Characterization of sotorasib and other His95-groove binders revealed enhanced potency and selectivity as compared to other KRASG12C inhibitor scaffolds, which bind in the P2 pocket via hydrogen bonding with His95. The novel binding mode of sotorasib also translated to similar biochemical and cellular potencies against both NRASG12C and HRASG12C, which encode leucine and glutamine at position 95, respectively. In contrast, other KRASG12C inhibitor scaffolds demonstrated a dramatic loss of potency against NRASG12C and HRASG12C, suggesting that the alternate residues impacted the binding of these molecules in the P2 pocket. To extend characterization of the cellular effects of RAS ‘His95-groove' binders, we analyzed the expression of major histocompatibility complex (MHC) class I proteins and other inflammatory markers in multiple human and murine KRAS p.G12C cell lines. These studies revealed a partial dependency on the cytosolic DNA-sensing (cGAS/STING) pathway for the effects observed with some markers. Finally, His95-groove binders were evaluated for potential mechanisms of resistance to this class of KRASG12C inhibitors. In the mouse syngeneic Lewis Lung Carcinoma (LL/2) cell line, which carries both KRAS p.G12C and NRAS p.Q61H mutations, intrinsic resistance to KRASG12C inhibition was observed, but combination treatment with the MEK inhibitor trametinib demonstrated synergistic improvement in the effects on viability. MIA PaCa-2 and NCI-H358 models of acquired resistance to KRASG12C inhibition were also developed through long-term exposure to high concentrations of sotorasib. Characterization of these resistant cell lines indicated a requirement for constant exposure to sotorasib and also showed that the resistance was not due to genetic alterations but involved either overexpression of KRAS or bypass signaling through alternative pathways. Taken together, these data demonstrate that His95-binders like sotorasib display superior potency and off-target selectivity, as well as unique activity against all versions of RASG12C. In addition, characterization of potential resistance mechanisms to sotorasib will inform combination strategies in the clinic. Citation Format: Anne Y. Saiki, Deanna Mohn, Yu Li, Tao Osgood, Karen Rex, Hui-Ling Wang, Ivonne Archibeque, Christopher Mohr, Pragathi Achanta, Andres Plata Stapper, Aaron S. Rapaport, Jude Canon, Victor J. Cee, Brian A. Lanman, J. Russell Lipford. In vitro characterization of sotorasib and other RAS ‘His95-groove' binders and investigation of resistance mechanisms [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 1285.

The prosurvival BCL2 family member MCL1 is frequently dysregulated in cancer. To overcome the significant challenges associated with inhibition of MCL1 protein–protein interactions, we rigorously applied small-molecule conformational restriction, which culminated in the discovery of AMG 176, the first selective MCL1 inhibitor to be studied in humans. We demonstrate that MCL1 inhibition induces a rapid and committed step toward apoptosis in subsets of hematologic cancer cell lines, tumor xenograft models, and primary patient samples. With the use of a human MCL1 knock-in mouse, we demonstrate that MCL1 inhibition at active doses of AMG 176 is tolerated and correlates with clear pharmacodynamic effects, demonstrated by reductions in B cells, monocytes, and neutrophils. Furthermore, the combination of AMG 176 and venetoclax is synergistic in acute myeloid leukemia (AML) tumor models and in primary patient samples at tolerated doses. These results highlight the therapeutic promise of AMG 176 and the potential for combinations with other BH3 mimetics. Significance: AMG 176 is a potent, selective, and orally bioavailable MCL1 inhibitor that induces a rapid commitment to apoptosis in models of hematologic malignancies. The synergistic combination of AMG 176 and venetoclax demonstrates robust activity in models of AML at tolerated doses, highlighting the promise of BH3-mimetic combinations in hematologic cancers. See related commentary by Leber et al., p. 1511. This article is highlighted in the In This Issue feature, p. 1494

Structure-based rational design and extensive structure-activity relationship studies led to the discovery of AMG 232 (1), a potent piperidinone inhibitor of the MDM2-p53 association, which is currently being evaluated in human clinical trials for the treatment of cancer. Further modifications of 1, including replacing the carboxylic acid with a 4-amidobenzoic acid, afforded AM-7209 (25), featuring improved potency (KD from ITC competition was 38 pM, SJSA-1 EdU IC50 = 1.6 nM), remarkable pharmacokinetic properties, and in vivo antitumor activity in both the SJSA-1 osteosarcoma xenograft model (ED50 = 2.6 mg/kg QD) and the HCT-116 colorectal carcinoma xenograft model (ED50 = 10 mg/kg QD). In addition, 25 possesses distinct mechanisms of elimination compared to 1.

Continued optimization of the N-substituent in the piperidinone series provided potent piperidinone-pyridine inhibitors 6, 7, 14, and 15 with improved pharmacokinetic properties in rats. Reducing structure complexity of the N-alkyl substituent led to the discovery of 23, a potent and simplified inhibitor of MDM2. Compound 23 exhibits excellent pharmacokinetic properties and substantial in vivo antitumor activity in the SJSA-1 osteosarcoma xenograft mouse model.

While MDM2 inhibitors hold great promise as cancer therapeutics, drug resistance will likely limit their efficacy as single agents. To identify drug combinations that might circumvent resistance, we screened for agents that could synergize with MDM2 inhibition in the suppression of cell viability. We observed broad and robust synergy when combining MDM2 antagonists with either MEK or PI3K inhibitors. Synergy was not limited to cell lines harboring MAPK or PI3K pathway mutations, nor did it depend on which node of the PI3K axis was targeted. MDM2 inhibitors also synergized strongly with BH3 mimetics, BCR-ABL antagonists, and HDAC inhibitors. MDM2 inhibitor-mediated synergy with agents targeting these mechanisms was much more prevalent than previously appreciated, implying that clinical translation of these combinations could have far-reaching implications for public health. These findings highlight the importance of combinatorial drug targeting and provide a framework for the rational design of MDM2 inhibitor clinical trials.

We previously reported the discovery of AMG 232, a highly potent and selective piperidinone inhibitor of the MDM2-p53 interaction. Our continued search for potent and diverse analogues led to the discovery of novel morpholinone MDM2 inhibitors. This change to a morpholinone core has a significant impact on both potency and metabolic stability compared to the piperidinone series. Within this morpholinone series, AM-8735 emerged as an inhibitor with remarkable biochemical potency (HTRF IC50 = 0.4 nM) and cellular potency (SJSA-1 EdU IC50 = 25 nM), as well as pharmacokinetic properties. Compound 4 also shows excellent antitumor activity in the SJSA-1 osteosarcoma xenograft model with an ED50 of 41 mg/kg. Lead optimization toward the discovery of this inhibitor as well as key differences between the morpholinone and the piperidinone series will be described herein.

Acute myeloid leukemia (AML) is a heterogeneous malignancy involving the clonal expansion of abnormal myeloid progenitor cells. The anti-apoptotic BCL-2 protein family member MCL1 has been implicated in AML pathogenesis. AMG 176 is a potent and selective MCL1 inhibitor currently being evaluated in an AML Phase I clinical trial. Standard of care (SOC) treatment for AML involves “7+3” induction therapy with cytarabine and an anthracycline (i.e. doxorubicin). In patient’s ineligible for conventional induction therapy, the hypomethylating agent decitabine is a well-tolerated alternative. Here we investigate the activity of AMG 176 and AM-8621, a closely related analog of AMG 176 with similar potency and selectivity, in combination with SOC therapies in preclinical models of AML. We profiled a panel of AML cell lines (MOLM-13, MV-4-11, GDM-1 and EOL-1), testing AM-8621 in combination with cytarabine, doxorubicin and decitabine in 3-day viability assays. Evidence for synergistic activity was detected with each of the combinations across subsets of the cell lines. A time course of AM-8621 treatment revealed a rapid induction of caspase 3/7 activity, with significant increases observed within the first 2-4 hours of treatment while longer duration treatment (>8 hours) was required to activate caspase 3/7 with SOC agents. Combined treatment with AM-8621 and SOC agents exhibited significant improvements in caspase 3/7 activity beyond either single agent alone. To provide mechanistic insight into the ability of SOC agents to sensitize AML cell lines to AM-8621 treatment, signaling experiments were performed to characterize changes in BCL-2 protein family members following treatment with SOC agents. Clear changes in the levels of anti-apoptotic BCL-2 family members (MCL1, BCL-2 and BCL-XL), BH3-only domain containing proteins (BIM, NOXA, PUMA) and the executioner protein BAK were observed, providing insight into potential mechanisms of priming cells to MCL1 inhibition. Combinations of AMG 176 and each of the SOC therapies were also tested in a MOLM-13 orthotopic xenograft model of AML. Mice were treated with combinations of AMG 176 and cytarabine, decitabine or doxorubicin and compared against the single agent therapies. Significant reductions in tumor burden compared to single agent treatments were observed with the AMG 176 + doxorubicin (30% regression) and AMG 176 + decitabine (98% tumor growth inhibition) combinations. These data highlight the promise of combining AMG 176 with SOC therapies in the setting of AML. Citation Format: Sean Caenepeel, Brian Belmontes, Tao Osgood, Elaina Cajulis, Angela Coxon, Jude Canon, Paul E. Hughes. AMG 176 exhibits robust antitumor activity in combination with standard of care agents in models of acute myeloid leukemia [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 2180.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy involving the clonal expansion of immature myeloid cells. Dysregulated expression of the BCL-2 family of proteins has been implicated in AML pathogenesis. Specifically, the anti-apoptotic family members MCL1 and BCL-2 have been reported to play key roles in AML survival. The selective inhibition of these two proteins represents an emerging strategy in AML treatment. AMG 176 is a potent and selective MCL1 inhibitor currently being tested in an AML Phase I clinical trial. Here we describe the activity of AMG 176 and AM-8621, a structural analog, as single agents and in combination with the BCL-2 inhibitor venetoclax, in models of AML. AM-8621 and venetoclax were profiled as single agents against a panel of AML cell lines to characterize their dependency on MCL1 and BCL-2 for survival. A wide range of sensitivities to both compounds was observed, with several lines exhibiting dependency on both MCL1 and BCL-2 for survival, suggesting functional redundancy and a requirement for combined inhibition to maximize response. To test this hypothesis, we profiled a subset of cell lines with the combination of AM-8621 and venetoclax. A synergistic interaction was detected in each cell line, highlighting their codependence on MCL1 and BCL-2. We also evaluated the synergistic potential of this combination on primary AML patient samples. Here, freshly purified bone marrow aspirates were treated with equimolar concentrations of AM-8621 and venetoclax and compared against single agents in a flow cytometry based viability assay. Marked improvements in activity and potency were observed with the combination over either agent alone. We also tested the combination of AMG 176 and venetoclax in a MOLM-13 orthotopic xenograft model of AML. Mice were treated twice weekly with AMG 176 (60 mg/kg) and daily with venetoclax (100 mg/kg). While both single agents achieved significant reductions in MOLM-13 tumor burden (69% and 33% reduction in BLI respectively), the combination exhibited complete inhibition of tumor growth (100% reduction in BLI) and achieved tumor regression relative to the first day of dosing. We next characterized the effects of this combination on subsets of hematopoietic cells in vivo. The reduced affinity of AMG 176 for murine MCL1 (200-fold) required the use of a human MCL1 knock-in mouse for these studies. Terminal analysis of mice treated with the combination or AMG 176 alone showed significant decreases in peripheral blood B-cells and monocytes, whereas venetoclax alone exhibited significant reductions in B-cells only. Analysis of spleens revealed greater reductions in both cell types following treatment with the combination compared with either single agent. These data highlight the promise of combined MCL1 and BCL2 inhibition as a novel therapeutic strategy for the treatment of AML. Citation Format: Sean R. Caenepeel, Tao Osgood, Brian Belmontes, Jan Sun, Elaina Cajulis, Andrew Wei, Angela Coxon, Jude Canon, Paul Hughes. Combined inhibition of MCL1 and BCL-2 with AMG 176 and venetoclax induces anti-tumor effects in primary patient samples and models of acute myeloid leukemia [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 3972.

Hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, c-Met, have been implicated in the growth and progression of a variety of solid human tumors. Thus, inhibiting HGF/SF:c-Met signaling may provide a novel therapeutic approach for treating human tumors. We have generated and characterized fully human monoclonal antibodies that bind to and neutralize human HGF/SF. In this study, we tested the effects of the investigational, human anti-human HGF/SF monoclonal antibody, AMG 102, and a mixture of mouse anti-human HGF/SF monoclonal antibodies (Amix) on HGF/SF-mediated cell migration, proliferation, and invasion in vitro. Both agents had high HGF/SF-neutralizing activity in these cell-based assays. The HGF/SF:c-Met pathway has been implicated in the growth of sarcomas; thus, we also investigated the effect of AMG 102 on the growth of human leiomyosarcoma (SK-LMS-1) in HGF/SF transgenic C3H severe combined immunodeficient mice engineered to express high levels of human HGF/SF, as well as tumor growth of an autocrine variant of the SK-LMS-1 cell line (SK-LMS-1TO) in nude mice. The results indicate that interrupting autocrine and/or paracrine HGF/SF:c-Met signaling with AMG 102 has profound antitumor effects. These findings suggest that blocking HGF/SF:c-Met signaling may provide a potent intervention strategy to treat patients with HGF/SF:c-Met–dependent tumors. [Mol Cancer Ther 2009;8(10):2803–10]

Recepteur d'origine nantais (RON) is a receptor tyrosine kinase closely related to c-Met. Both receptors are involved in cell proliferation, migration, and invasion, and there is evidence that both are deregulated in cancer. Receptor overexpression has been most frequently described, but other mechanisms can lead to the oncogenic activation of RON and c-Met. They include activating mutations or gene amplification for c-Met and constitutively active splicing variants for RON. We identified a novel inhibitor of RON and c-Met, compound I, and characterized its in vitro and in vivo activities. Compound I selectively and potently inhibited the kinase activity of RON and c-Met with IC50s of 9 and 4 nmol/L, respectively. Compound I inhibited hepatocyte growth factor–mediated and macrophage-stimulating protein–mediated signaling and cell migration in a dose-dependent manner. Compound I was tested in vivo in xenograft models that either were dependent on c-Met or expressed a constitutively active form of RON (RONΔ160 in HT-29). Compound I caused complete tumor growth inhibition in NIH3T3 TPR-Met and U-87 MG xenografts but showed only partial inhibition in HT-29 xenografts. The effect of compound I in HT-29 xenografts is consistent with the expression of the activating b-Raf V600E mutation, which activates the mitogen-activated protein kinase pathway downstream of RON. Importantly, tumor growth inhibition correlated with the inhibition of c-Met–dependent and RON-dependent signaling in tumors. Taken together, our results suggest that a small-molecule dual inhibitor of RON/c-Met has the potential to inhibit tumor growth and could therefore be useful for the treatment of patients with cancers where RON and/or c-Met are activated. [Cancer Res 2008;68(16):6680–7]

p53 is a critical tumor suppressor and is the most frequently inactivated gene in human cancer. Inhibition of the interaction of p53 with its negative regulator MDM2 represents a promising clinical strategy to treat p53 wild-type tumors. AMG 232 is a potential best-in-class inhibitor of the MDM2–p53 interaction and is currently in clinical trials. We characterized the activity of AMG 232 and its effect on p53 signaling in several preclinical tumor models. AMG 232 binds the MDM2 protein with picomolar affinity and robustly induces p53 activity, leading to cell-cycle arrest and inhibition of tumor cell proliferation. AMG 232 treatment inhibited the in vivo growth of several tumor xenografts and led to complete and durable regression of MDM2-amplified SJSA-1 tumors via growth arrest and induction of apoptosis. Therapeutic combination studies of AMG 232 with chemotherapies that induce DNA damage and p53 activity resulted in significantly superior antitumor efficacy and regression, and markedly increased activation of p53 signaling in tumors. These preclinical data support the further evaluation of AMG 232 in clinical trials as both a monotherapy and in combination with standard-of-care cytotoxics. Mol Cancer Ther; 14(3); 649–58. ©2015 AACR.

We previously reported the discovery of potent and selective morpholinone and piperidinone inhibitors of the MDM2-p53 interaction. These inhibitors have in common a carboxylic acid moiety that engages in an electrostatic interaction with MDM2-His96. Our continued search for potent and diverse inhibitors led to the discovery of novel replacements for these acids uncovering new interactions with the MDM2 protein. In particular, using pyridine or thiazole as isosteres of the carboxylic acid moiety resulted in very potent analogues. From these, AM-6761 (4) emerged as a potent inhibitor with remarkable biochemical (HTRF IC50 = 0.1 nM) and cellular potency (SJSA-1 EdU IC50 = 16 nM), as well as favorable pharmacokinetic properties. Compound 4 also shows excellent antitumor activity in the SJSA-1 osteosarcoma xenograft model with an ED50 of 11 mg/kg. Optimization efforts toward the discovery of these inhibitors as well as the new interactions observed with the MDM2 protein are described herein.

Structural analysis of both the MDM2-p53 protein-protein interaction and several small molecules bound to MDM2 led to the design and synthesis of tetrasubstituted morpholinone 10, an MDM2 inhibitor with a biochemical IC50 of 1.0 μM. The cocrystal structure of 10 with MDM2 inspired two independent optimization strategies and resulted in the discovery of morpholinones 16 and 27 possessing distinct binding modes. Both analogues were potent MDM2 inhibitors in biochemical and cellular assays, and morpholinone 27 (IC50 = 0.10 μM) also displayed suitable PK profile for in vivo animal experiments. A pharmacodynamic (PD) experiment in mice implanted with human SJSA-1 tumors showed p21(WAF1) mRNA induction (2.7-fold over vehicle) upon oral dosing of 27 at 300 mg/kg.

AMG 232 is a potent inhibitor of the MDM2-p53 interaction and is a promising clinical candidate for treating tumors, in particular those harboring wild-type p53. AML represents a compelling indication for AMG 232 given the low rate of p53 mutation, frequent MDM2 overexpression, and unmet medical need. We evaluated the effect of AMG 232 treatment on AML tumors in vitro and in vivo, elucidated the mechanism of anti-tumor efficacy, and tested the effect of combining AMG 232 with targeted agents and chemotherapeutics. Combinations were identified based on evidence of in vitro synergy from cell based screens, or based on biological rationale and clinical opportunity with standard of care agents. Combinations evaluated included MEK inhibitors, and p53-inducing, DNA-damaging cytotoxics cytarabine, doxorubicin, and decitabine. In vitro assays demonstrated that AMG 232 as a single agent was effective at inducing cell death across a panel of p53 wild-type AML cell lines. The anti-tumor efficacy involved activation of the p53 pathway, robust inhibition of the cell cycle and induction of apoptosis. AMG 232 treatment caused AML tumor regression in vivo which was related to dose- and time-dependent induction of the p53 targets p21 and PUMA. The combination of AMG 232 and MEK inhibition resulted in synergistic tumor cell killing in vitro, and enhanced in vivo anti-tumor activity which was significantly better than either single agent. Combinations of AMG 232 with chemotherapies which induce DNA damage resulted in synergistic in vitro cell killing, and superior anti-tumor efficacy in vivo with increased induction of p53 signaling in tumors. These data support a clinical strategy for evaluating AMG 232 as a monotherapy and in combination with targeted and cytotoxic agents to treat AML patients. Citation Format: Jude R. Canon, Tao Osgood, Anne Y. Saiki, Jonathan D. Oliner. The MDM2 inhibitor AMG 232 causes tumor regression and potentiates the anti-tumor activity of MEK inhibition and DNA-damaging cytotoxic agents in preclinical models of acute myeloid leukemia. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3761.

Structure-based rational design led to the discovery of novel inhibitors of the MDM2–p53 protein–protein interaction. The affinity of these compounds for MDM2 was improved through conformational control of both the piperidinone ring and the appended N-alkyl substituent. Optimization afforded 29 (AM-8553), a potent and selective MDM2 inhibitor with excellent pharmacokinetic properties and in vivo efficacy.

The p53 tumor suppressor is controlled by MDM2, which binds p53 and negatively regulates its transcriptional activity and stability. Many tumors overproduce MDM2 to impair p53 function. Therefore, restoration of p53 activity by inhibiting p53-MDM2 binding represents an attractive, novel approach to cancer therapy. We previously reported the discovery of AM-8553, a potent and selective piperidinone inhibitor of the MDM2-p53 interaction (Rew et al. J. Med. Chem. 2012, 55, 4936). We report here continued optimization of the N-alkyl substituent of this series, focused in particular on a previously underutilized interaction in a shallow cleft on the MDM2 surface that led to the discovery of a variety of extremely potent sulfonamides such as 14 with an IC50 of 5.3 nM in the cell proliferation assay. The compound 14 interacts specifically with the p53-binding pocket of MDM2 and releases the p53 protein from negative control. Treatment of cancer cells expressing wild-type p53 with sulfonamide 14 stabilizes p53 and activates the p53 pathway, leading to cell cycle arrest and apoptosis. The compound 14 showed excellent efficacy and caused tumor regression in the SJSA-1 tumor xenograft model. Citation Format: Zhihong Li, Jiasheng Fu, Yosup Rew, Michael W. Gribble, Jude Canon, Ada Chen, John Eksterowicz, Xin Huang, Lixia Jin, Mei-Chu Lo, Lawrence R. McGee, Tao Osgood, Anne Y. Saiki, Paul Shaffer, Daqing Sun, Sarah Wortman, Qiuping Ye, Dongyin Yu, Xiaoning Zhao, Jing Zhou, Jonathan D. Oliner, Steve H. Olson, Julio C. Medina. Discovery of sulfonamide-piperidinones as potent inhibitors of the MDM2-p53 protein-protein interaction. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3663. doi:10.1158/1538-7445.AM2015-3663