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Kahraman M, Govek SP, Nagasawa JY, Lai A, Bonnefous C, Douglas K, Sensintaffar J, Liu N, Lee K, Aparicio A, Kaufman J, Qian J, Shao G, Prudente R, Joseph JD, Darimont B, Brigham D, Heyman R, Rix PJ, Hager JH, Smith ND. Maximizing ER-α Degradation Maximizes Activity in a Tamoxifen-Resistant Breast Cancer Model: Identification of GDC-0927. ACS Med Chem Lett 2019; 10:50-55. [PMID: 30655946 DOI: 10.1021/acsmedchemlett.8b00414] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 12/06/2018] [Indexed: 02/07/2023] Open
Abstract
The further optimization of ER-α degradation efficacy of a series of ER modulators by refining side-chain substitution led to efficacious selective estrogen receptor degraders (SERDs). A fluoromethyl azetidine group was found to be preferred and resulted in the identification of bis-phenol chromene 17ha. In a tamoxifen-resistant breast cancer xenograft model, 17ha (ER-α degradation efficacy = 97%) demonstrated tumor regression, together with robust reduction of intratumoral ER-α levels. However, despite superior oral exposure, 5a (ER-α degradation efficacy = 91%) had inferior activity. This result suggests that optimizing ER-α degradation efficacy leads to compounds with robust effects in a model of tamoxifen-resistant breast cancer. Compound 17ha (GDC-0927) was evaluated in clinical trials in women with metastatic estrogen receptor-positive breast cancer.
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Joseph JD, Darimont B, Zhou W, Arrazate A, Young A, Ingalla E, Walter K, Blake RA, Nonomiya J, Guan Z, Kategaya L, Govek SP, Lai AG, Kahraman M, Brigham D, Sensintaffar J, Lu N, Shao G, Qian J, Grillot K, Moon M, Prudente R, Bischoff E, Lee KJ, Bonnefous C, Douglas KL, Julien JD, Nagasawa JY, Aparicio A, Kaufman J, Haley B, Giltnane JM, Wertz IE, Lackner MR, Nannini MA, Sampath D, Schwarz L, Manning HC, Tantawy MN, Arteaga CL, Heyman RA, Rix PJ, Friedman L, Smith ND, Metcalfe C, Hager JH. Correction: The selective estrogen receptor downregulator GDC-0810 is efficacious in diverse models of ER+ breast cancer. eLife 2019; 8:44851. [PMID: 30614786 PMCID: PMC6322858 DOI: 10.7554/elife.44851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Nagasawa J, Govek S, Kahraman M, Lai A, Bonnefous C, Douglas K, Sensintaffar J, Lu N, Lee K, Aparicio A, Kaufman J, Qian J, Shao G, Prudente R, Joseph JD, Darimont B, Brigham D, Maheu K, Heyman R, Rix PJ, Hager JH, Smith ND. Identification of an Orally Bioavailable Chromene-Based Selective Estrogen Receptor Degrader (SERD) That Demonstrates Robust Activity in a Model of Tamoxifen-Resistant Breast Cancer. J Med Chem 2018; 61:7917-7928. [PMID: 30086626 DOI: 10.1021/acs.jmedchem.8b00921] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
About 75% of breast cancers are estrogen receptor alpha (ER-α) positive, and women typically initially respond well to antihormonal therapies such as tamoxifen and aromatase inhibitors, but resistance often emerges. Fulvestrant is a steroid-based, selective estrogen receptor degrader (SERD) that both antagonizes and degrades ER-α and shows some activity in patients who have progressed on antihormonal agents. However, fulvestrant must be administered by intramuscular injections that limit its efficacy. We describe the optimization of ER-α degradation efficacy of a chromene series of ER modulators resulting in highly potent and efficacious SERDs such as 14n. When examined in a xenograft model of tamoxifen-resistant breast cancer, 14n (ER-α degradation efficacy = 91%) demonstrated robust activity, while, despite superior oral exposure, 15g (ER-α degradation efficacy = 82%) was essentially inactive. This result suggests that optimizing ER-α degradation efficacy in the MCF-7 cell line leads to compounds with robust effects in models of tamoxifen-resistant breast cancer derived from an MCF-7 background.
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Kahraman M, Govek SP, Nagasawa JY, Lai A, Bonnefous C, Douglas K, Sensintaffar J, Lu N, Lee K, Aparicio A, Kaufman J, Qian J, Shao G, Prudente R, Joseph JD, Darimont B, Brigham D, Heyman R, Rix PJ, Hager JH, Smith ND, Blake RA, Chang J, Choo E, Daemen A, Friedman LS, Guan J, Hartman S, Ingalla E, Kiefer JR, Kleinheinz T, Labadie S, Metcalfe C, Mody V, Nannini M, Sampath D, Young A, Vinogradova M, Zhou W, Liang J, Wang X. Abstract 1648: Discovery and evolution of orally bioavailable selective estrogen receptor degraders for ER+ breast cancer: From GDC-0810 to GDC-0927. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-1648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Breast cancer is the most frequently diagnosed cancer among women and remains the second leading cause of cancer death in women. An estimated 70% of all breast cancers express estrogen receptor alpha (ERα); and endocrine therapies have validated ERα as a target for the treatment of breast cancer. Despite effective endocrine therapies, many patients eventually relapse and become resistant to standard of care treatments. Endocrine resistant tumors often remain dependent on ERα for growth and survival, as evidenced by their sensitivity to the selective estrogen receptor degrader (SERD), fulvestrant. However, fulvestrant may be limited in achieving maximal target occupancy due to pharmaceutical and pharmacokinetics properties which necessitates intramuscular route of administration. Consequently, SERDs with superior drug-like properties were sought to allow consistent and rapid achievement of maximal therapeutic exposure. GDC-0810 and GDC-0927 as first and second generation orally bioavailable SERDs were discovered through a prospective lead optimization on ERα degradation. The evolution from GDC-0810 to GDC-0927 will be described and provides new insights into ERα biology and biochemistry. By shifting away from the acrylic acid moiety in GDC-0810, GDC-0927 achieved increased potency and more consistent, complete suppression of ER signaling. Co-crystal structures of both GDC-0810 and GDC-0927 with ERα will be shared. Subsequent optimization of GDC-0927 resulting in improved pharmacokinetic properties will also be highlighted.
Citation Format: Mehmet Kahraman, Steven P. Govek, Johnny Y. Nagasawa, Andiliy Lai, Celine Bonnefous, Karensa Douglas, John Sensintaffar, Nhin Lu, KyoungJin Lee, Anna Aparicio, Josh Kaufman, Jing Qian, Gang Shao, Rene Prudente, James D. Joseph, Beatrice Darimont, Daniel Brigham, Richard Heyman, Peter J. Rix, Jeffrey H. Hager, Nicholas D. Smith, Robert A. Blake, Jae Chang, Edna Choo, Anneleen Daemen, Lori S. Friedman, Jane Guan, Steven Hartman, Ellen Ingalla, James R. Kiefer, Tracy Kleinheinz, Sharada Labadie, Ciara Metcalfe, Vidhi Mody, Michelle Nannini, Deepak Sampath, Amy Young, Maia Vinogradova, Wei Zhou, Jun Liang, Xiaojing Wang. Discovery and evolution of orally bioavailable selective estrogen receptor degraders for ER+ breast cancer: From GDC-0810 to GDC-0927 [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 1648.
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Affiliation(s)
| | | | | | | | | | | | | | - Nhin Lu
- Genentech Inc, South San Francisco, CA
| | | | | | | | - Jing Qian
- Genentech Inc, South San Francisco, CA
| | - Gang Shao
- Genentech Inc, South San Francisco, CA
| | | | | | | | | | | | | | | | | | | | - Jae Chang
- Genentech Inc, South San Francisco, CA
| | - Edna Choo
- Genentech Inc, South San Francisco, CA
| | | | | | - Jane Guan
- Genentech Inc, South San Francisco, CA
| | | | | | | | | | | | | | | | | | | | - Amy Young
- Genentech Inc, South San Francisco, CA
| | | | - Wei Zhou
- Genentech Inc, South San Francisco, CA
| | - Jun Liang
- Genentech Inc, South San Francisco, CA
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5
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Joseph JD, Darimont B, Zhou W, Arrazate A, Young A, Ingalla E, Walter K, Blake RA, Nonomiya J, Guan Z, Kategaya L, Govek SP, Lai AG, Kahraman M, Brigham D, Sensintaffar J, Lu N, Shao G, Qian J, Grillot K, Moon M, Prudente R, Bischoff E, Lee KJ, Bonnefous C, Douglas KL, Julien JD, Nagasawa JY, Aparicio A, Kaufman J, Haley B, Giltnane JM, Wertz IE, Lackner MR, Nannini MA, Sampath D, Schwarz L, Manning HC, Tantawy MN, Arteaga CL, Heyman RA, Rix PJ, Friedman L, Smith ND, Metcalfe C, Hager JH. The selective estrogen receptor downregulator GDC-0810 is efficacious in diverse models of ER+ breast cancer. eLife 2016; 5:15828. [PMID: 27410477 PMCID: PMC4961458 DOI: 10.7554/elife.15828] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 07/09/2016] [Indexed: 12/14/2022] Open
Abstract
ER-targeted therapeutics provide valuable treatment options for patients with ER+ breast cancer, however, current relapse and mortality rates emphasize the need for improved therapeutic strategies. The recent discovery of prevalent ESR1 mutations in relapsed tumors underscores a sustained reliance of advanced tumors on ERα signaling, and provides a strong rationale for continued targeting of ERα. Here we describe GDC-0810, a novel, non-steroidal, orally bioavailable selective ER downregulator (SERD), which was identified by prospectively optimizing ERα degradation, antagonism and pharmacokinetic properties. GDC-0810 induces a distinct ERα conformation, relative to that induced by currently approved therapeutics, suggesting a unique mechanism of action. GDC-0810 has robust in vitro and in vivo activity against a variety of human breast cancer cell lines and patient derived xenografts, including a tamoxifen-resistant model and those that harbor ERα mutations. GDC-0810 is currently being evaluated in Phase II clinical studies in women with ER+ breast cancer.
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Affiliation(s)
- James D Joseph
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Beatrice Darimont
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Wei Zhou
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Alfonso Arrazate
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Amy Young
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Ellen Ingalla
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Kimberly Walter
- Department of Oncology Biomarker Development, Genentech, South San Francisco, United States
| | - Robert A Blake
- Department of Biochemical and Cellular Pharmacology, Genentech, South San Francisco, United States
| | - Jim Nonomiya
- Department of Biochemical and Cellular Pharmacology, Genentech, South San Francisco, United States
| | - Zhengyu Guan
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Lorna Kategaya
- Departments of Discovery Oncology and Early Discovery Biochemistry, Genentech, South San Francisco, United States
| | - Steven P Govek
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Andiliy G Lai
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Mehmet Kahraman
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Dan Brigham
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - John Sensintaffar
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Nhin Lu
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Gang Shao
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Jing Qian
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Kate Grillot
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Michael Moon
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Rene Prudente
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Eric Bischoff
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Kyoung-Jin Lee
- Department of Drug Safety and Disposition, Seragon Pharmaceuticals, San Diego, United States
| | - Celine Bonnefous
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Karensa L Douglas
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Jackaline D Julien
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Johnny Y Nagasawa
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Anna Aparicio
- Department of Drug Safety and Disposition, Seragon Pharmaceuticals, San Diego, United States
| | - Josh Kaufman
- Department of Drug Safety and Disposition, Seragon Pharmaceuticals, San Diego, United States
| | - Benjamin Haley
- Department of Molecular Biology, Genentech, South San Francisco, United States
| | | | - Ingrid E Wertz
- Departments of Discovery Oncology and Early Discovery Biochemistry, Genentech, South San Francisco, United States
| | - Mark R Lackner
- Department of Oncology Biomarker Development, Genentech, South San Francisco, United States
| | - Michelle A Nannini
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Deepak Sampath
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Luis Schwarz
- Department of Medicine and Breast Cancer Program, Vanderbilt-Ingram Cancer Center, Nashville, United States
| | - Henry Charles Manning
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, United States
| | - Mohammed Noor Tantawy
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, United States
| | - Carlos L Arteaga
- Department of Medicine and Breast Cancer Program, Vanderbilt-Ingram Cancer Center, Nashville, United States
| | - Richard A Heyman
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
| | - Peter J Rix
- Department of Drug Safety and Disposition, Seragon Pharmaceuticals, San Diego, United States
| | - Lori Friedman
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Nicholas D Smith
- Department of Chemistry, Seragon Pharmaceuticals, San Diego, United States
| | - Ciara Metcalfe
- Department of Translational Oncology, Genentech, South San Francisco, United States
| | - Jeffrey H Hager
- Department of Biology, Seragon Pharmaceuticals, San Diego, United States
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6
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Govek SP, Nagasawa JY, Douglas KL, Lai AG, Kahraman M, Bonnefous C, Aparicio AM, Darimont BD, Grillot KL, Joseph JD, Kaufman JA, Lee KJ, Lu N, Moon MJ, Prudente RY, Sensintaffar J, Rix PJ, Hager JH, Smith ND. Optimization of an indazole series of selective estrogen receptor degraders: Tumor regression in a tamoxifen-resistant breast cancer xenograft. Bioorg Med Chem Lett 2015; 25:5163-7. [PMID: 26463130 DOI: 10.1016/j.bmcl.2015.09.074] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 09/26/2015] [Accepted: 09/30/2015] [Indexed: 10/22/2022]
Abstract
Selective estrogen receptor degraders (SERDs) have shown promise for the treatment of ER+ breast cancer. Disclosed herein is the continued optimization of our indazole series of SERDs. Exploration of ER degradation and antagonism in vitro followed by in vivo antagonism and oral exposure culminated in the discovery of indazoles 47 and 56, which induce tumor regression in a tamoxifen-resistant breast cancer xenograft.
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Affiliation(s)
- Steven P Govek
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States.
| | - Johnny Y Nagasawa
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Karensa L Douglas
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Andiliy G Lai
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Mehmet Kahraman
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Celine Bonnefous
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Anna M Aparicio
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Beatrice D Darimont
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Katherine L Grillot
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - James D Joseph
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Joshua A Kaufman
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Kyoung-Jin Lee
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Nhin Lu
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Michael J Moon
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Rene Y Prudente
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - John Sensintaffar
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Peter J Rix
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Jeffrey H Hager
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
| | - Nicholas D Smith
- Seragon Pharmaceuticals, Inc., 12780 El Camino Real, Suite 302, San Diego, CA 92130, United States
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7
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Lai A, Kahraman M, Govek S, Nagasawa J, Bonnefous C, Julien J, Douglas K, Sensintaffar J, Lu N, Lee KJ, Aparicio A, Kaufman J, Qian J, Shao G, Prudente R, Moon MJ, Joseph JD, Darimont B, Brigham D, Grillot K, Heyman R, Rix PJ, Hager JH, Smith ND. Identification of GDC-0810 (ARN-810), an Orally Bioavailable Selective Estrogen Receptor Degrader (SERD) that Demonstrates Robust Activity in Tamoxifen-Resistant Breast Cancer Xenografts. J Med Chem 2015; 58:4888-904. [PMID: 25879485 DOI: 10.1021/acs.jmedchem.5b00054] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Approximately 80% of breast cancers are estrogen receptor alpha (ER-α) positive, and although women typically initially respond well to antihormonal therapies such as tamoxifen and aromatase inhibitors, resistance often emerges. Although a variety of resistance mechanism may be at play in this state, there is evidence that in many cases the ER still plays a central role, including mutations in the ER leading to constitutively active receptor. Fulvestrant is a steroid-based, selective estrogen receptor degrader (SERD) that both antagonizes and degrades ER-α and is active in patients who have progressed on antihormonal agents. However, fulvestrant suffers from poor pharmaceutical properties and must be administered by intramuscular injections that limit the total amount of drug that can be administered and hence lead to the potential for incomplete receptor blockade. We describe the identification and characterization of a series of small-molecule, orally bioavailable SERDs which are potent antagonists and degraders of ER-α and in which the ER-α degrading properties were prospectively optimized. The lead compound 11l (GDC-0810 or ARN-810) demonstrates robust activity in models of tamoxifen-sensitive and tamoxifen-resistant breast cancer, and is currently in clinical trials in women with locally advanced or metastatic estrogen receptor-positive breast cancer.
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Affiliation(s)
- Andiliy Lai
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Mehmet Kahraman
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Steven Govek
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Johnny Nagasawa
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Celine Bonnefous
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Jackie Julien
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Karensa Douglas
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - John Sensintaffar
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Nhin Lu
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Kyoung-Jin Lee
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Anna Aparicio
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Josh Kaufman
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Jing Qian
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Gang Shao
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Rene Prudente
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Michael J Moon
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - James D Joseph
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Beatrice Darimont
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Daniel Brigham
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Kate Grillot
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Richard Heyman
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Peter J Rix
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Jeffrey H Hager
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
| | - Nicholas D Smith
- †Department of Chemistry, ‡Department of Biology, §Department of Drug Safety and Disposition, Seragon Pharmaceuticals, 12780 El Camino Real, Suite 302, San Diego, California 92130, United States
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8
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Joseph JD, Aparicio A, Kaufman J, Julien J, Bonnefous C, Smith ND, Rix P, Jung ME, Sawyers CL, Heyman RA, Hager JH, Clegg NJ, Sensintaffar J, Lu N, Grillot K, Bischoff E, Shao G, Qian J, Darimont B. Abstract C16: Targeting AR in castration-resistant prostate cancer: Development of ARN-509 and second-generation antiandrogen resistance models. Cancer Res 2012. [DOI: 10.1158/1538-7445.prca2012-c16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The androgen receptor (AR) plays a central role in the development and progression of prostate cancer. Recent studies demonstrate that AR remains essential in the majority of castration resistant prostate cancer (CRPC) after classical androgen ablation therapies have failed. The clinical efficacies of MDV3100 and abiraterone acetate, both of which target the AR pathway in the castrate resistant setting, support these findings. ARN-509 is a 2nd generation competitive AR antagonist that, unlike bicalutamide, maintains full antagonist activity in preclinical CRPC models. ARN-509 does not robustly induce AR nuclear localization or DNA binding. However, ARN-509 displays maximal efficacy in the LNCaP/AR xenograft model of CRPC at lower dose and steady state plasma concentrations compared to MDV3100, suggesting potential for higher therapeutic index and ability to deliver the maximally efficacious dose in man. To date, ARN-509 has shown promising antitumor activity in mCRPC patients enrolled in a Phase 1 study. Given that approximately 50% of CRPC patients have suboptimal response to MDV3100 and abiraterone acetate as well as the observation that resistance eventually develops in patients who initially respond to therapy, we sought to determine whether AR remains a viable therapeutic target in the MDV3100 and ARN-509 resistant setting. To this end, we generated several MDV3100 and ARN-509 resistant derivatives of the LNCaP and LNCaP/AR cell lines. While work is underway to determine the molecular mechanisms of resistance, a subset of cell lines does not require androgens for growth in vitro. These androgen independent derivatives express AR at levels comparable to LNCaP/AR (approximately 3X LNCaP) or 2-3 fold LNCaP-AR. When representative lines are injected into castrated mice, they demonstrate a decreased latency of tumor formation compared to the parental cell line both in the presence and absence of ARN-509. Importantly, in all lines tested, small interfering RNA mediated reduction in AR levels dramatically impaired the ability of the androgen independent resistant cell lines to proliferate in the absence of androgens. These data support the hypothesis that AR remains a viable therapeutic target for second generation anti-androgen resistant prostate cancer and is the first step toward establishing a platform to screen for next generation anti-androgens.
Citation Format: James D. Joseph, Anna Aparicio, Josh Kaufman, Jackie Julien, Celine Bonnefous, Nicholas D. Smith, Peter Rix, Michael E. Jung, Charles L. Sawyers, Richard A. Heyman, Jeffrey H. Hager, Nicola J. Clegg, John Sensintaffar, Nhin Lu, Kate Grillot, Eric Bischoff, Gang Shao, Jing Qian, Beatrice Darimont. Targeting AR in castration-resistant prostate cancer: Development of ARN-509 and second-generation antiandrogen resistance models [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C16.
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Affiliation(s)
- James D. Joseph
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Anna Aparicio
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Josh Kaufman
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Jackie Julien
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Celine Bonnefous
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Nicholas D. Smith
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Peter Rix
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Michael E. Jung
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Charles L. Sawyers
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Richard A. Heyman
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Jeffrey H. Hager
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Nicola J. Clegg
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - John Sensintaffar
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Nhin Lu
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Kate Grillot
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Eric Bischoff
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Gang Shao
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Jing Qian
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Beatrice Darimont
- 1Aragon Pharmaceuticals, San Diego, CA, 2University of California, Los Angeles, CA, 3Memorial Sloan-Kettering Cancer Center, New York, NY
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Clegg NJ, Wongvipat J, Joseph JD, Tran C, Ouk S, Dilhas A, Chen Y, Grillot K, Bischoff ED, Cai L, Aparicio A, Dorow S, Arora V, Shao G, Qian J, Zhao H, Yang G, Cao C, Sensintaffar J, Wasielewska T, Herbert MR, Bonnefous C, Darimont B, Scher HI, Smith-Jones P, Klang M, Smith ND, De Stanchina E, Wu N, Ouerfelli O, Rix PJ, Heyman RA, Jung ME, Sawyers CL, Hager JH. ARN-509: a novel antiandrogen for prostate cancer treatment. Cancer Res 2012; 72:1494-503. [PMID: 22266222 DOI: 10.1158/0008-5472.can-11-3948] [Citation(s) in RCA: 490] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Continued reliance on the androgen receptor (AR) is now understood as a core mechanism in castration-resistant prostate cancer (CRPC), the most advanced form of this disease. While established and novel AR pathway-targeting agents display clinical efficacy in metastatic CRPC, dose-limiting side effects remain problematic for all current agents. In this study, we report the discovery and development of ARN-509, a competitive AR inhibitor that is fully antagonistic to AR overexpression, a common and important feature of CRPC. ARN-509 was optimized for inhibition of AR transcriptional activity and prostate cancer cell proliferation, pharmacokinetics, and in vivo efficacy. In contrast to bicalutamide, ARN-509 lacked significant agonist activity in preclinical models of CRPC. Moreover, ARN-509 lacked inducing activity for AR nuclear localization or DNA binding. In a clinically valid murine xenograft model of human CRPC, ARN-509 showed greater efficacy than MDV3100. Maximal therapeutic response in this model was achieved at 30 mg/kg/d of ARN-509, whereas the same response required 100 mg/kg/d of MDV3100 and higher steady-state plasma concentrations. Thus, ARN-509 exhibits characteristics predicting a higher therapeutic index with a greater potential to reach maximally efficacious doses in man than current AR antagonists. Our findings offer preclinical proof of principle for ARN-509 as a promising therapeutic in both castration-sensitive and castration-resistant forms of prostate cancer.
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Affiliation(s)
- Nicola J Clegg
- Human Oncology & Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
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Darimont B, Govek S, Joseph J, Grillot K, Bischoff E, Aparicio A, Bonnefous C, Douglas K, Julien J, Kahraman M, Kaufman J, Lai A, Lee KJ, Lu N, Nagasawa J, Prudente R, Qian J, Sensintaffar J, Shao G, Heyman R, Rix P, Smith N, Hager J. Abstract A133: A novel class of selective estrogen receptor degraders regresses tumors in preclinical models of endocrine-resistant breast cancer. Mol Cancer Ther 2011. [DOI: 10.1158/1535-7163.targ-11-a133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
60–75% of all breast cancers express the estrogen receptor (ER) and thus are treated with anti-hormonal therapies that directly block ER function (e.g. Tamoxifen) or hormone synthesis (Aromatase Inhibitors). While these therapies are initially effective, acquired resistance invariably emerges. Importantly, the majority of these tumors continue to express and depend on ER for growth and survival, suggesting that novel approaches to target ER signaling have tremendous potential to treat endocrine-resistant disease. We have identified novel ER antagonists that induce degradation of ER at picomolar concentrations resulting in significant reduction in steady state ER protein levels in breast cancer cell lines. These compounds yield regression in both Tamoxifen-sensitive and - resistant models of breast cancer in vivo. Based on their unique in vitro profile, good pharmacokinetics and oral bioavailability, these compounds represent a novel class of Selective Estrogen Receptor Degraders (SERDs) that hold tremendous promise as a next generation therapy for the treatment of ER+ breast cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A133.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Nhin Lu
- 1Aragon Pharmaceuticals, San Diego, CA
| | | | | | - Jing Qian
- 1Aragon Pharmaceuticals, San Diego, CA
| | | | - Gang Shao
- 1Aragon Pharmaceuticals, San Diego, CA
| | | | - Peter Rix
- 1Aragon Pharmaceuticals, San Diego, CA
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11
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Rowe BA, Schaffhauser H, Morales S, Lubbers LS, Bonnefous C, Kamenecka TM, McQuiston J, Daggett LP. Transposition of three amino acids transforms the human metabotropic glutamate receptor (mGluR)-3-positive allosteric modulation site to mGluR2, and additional characterization of the mGluR2-positive allosteric modulation site. J Pharmacol Exp Ther 2008; 326:240-51. [PMID: 18430863 DOI: 10.1124/jpet.108.138271] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glutamate is a major neurotransmitter in the central nervous system, and abnormal glutamate neurotransmission has been implicated in many neurological disorders, including schizophrenia, Alzheimer's disease, Parkinson's disease, addiction, anxiety, depression, epilepsy, and pain. Metabotropic glutamate receptors (mGluRs) activate intracellular signaling cascades in a G protein-dependent manner, which offer the opportunity for developing drugs that regulate glutamate neurotransmission in a functionally selective manner. In the present study, we further characterize the human mGluR2 (hmGluR2) potentiator binding site by showing that the substitution of the three amino acids found to be required for hmGluR2 potentiation, specifically Ser(688), Gly(689), and Asn(735), with the homologous hmGluR3 amino acids, inactivates the positive allosteric modulator activity of several structurally unique mGluR2 potentiators. Based on the characterization of the hmGluR2 potentiator binding site, we developed a novel scintillation proximity assay that was able to discriminate between compounds that were hmGluR2-specific potentiators, and those that were active on both hmGluR2 and hmGluR3. In addition, we substituted Ser(688), Gly(689), and Asn(735) into hmGluR3 and created an active hmGluR2 allosteric modulation site on the hmGluR3 receptor.
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Affiliation(s)
- Blake A Rowe
- Merck Research Laboratories, West Point, Pennsylvania, USA.
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Abrahamsson M, Becker HC, Hammarström L, Bonnefous C, Chamchoumis C, Thummel RP. Six-Membered Ring Chelate Complexes of Ru(II): Structural and Photophysical Effects. Inorg Chem 2007; 46:10354-64. [DOI: 10.1021/ic7011827] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria Abrahamsson
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Hans-Christian Becker
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Leif Hammarström
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Celine Bonnefous
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Charles Chamchoumis
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Randolph P. Thummel
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
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Govek SP, Bonnefous C, Hutchinson JH, Kamenecka T, McQuiston J, Pracitto R, Zhao LX, Gardner MF, James JK, Daggett LP, Rowe BA, Schaffhauser H, Bristow LJ, Campbell UC, Rodriguez DE, Vernier JM. Benzazoles as allosteric potentiators of metabotropic glutamate receptor 2 (mGluR2): efficacy in an animal model for schizophrenia. Bioorg Med Chem Lett 2005; 15:4068-72. [PMID: 16005222 DOI: 10.1016/j.bmcl.2005.06.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Revised: 06/02/2005] [Accepted: 06/03/2005] [Indexed: 10/25/2022]
Abstract
Metabotropic glutamate receptor 2 (mGluR2) has been implicated in a variety of CNS disorders, including schizophrenia. Disclosed herein is the development of a new series of allosteric potentiators of mGluR2. Structure-activity relationship studies in conjunction with pharmacokinetic data led to the discovery of indole 5, which is active in an animal model for schizophrenia.
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Affiliation(s)
- Steven P Govek
- Merck Research Laboratories, 3535 General Atomics Court, San Diego, CA 92121, USA.
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Hamill TG, Krause S, Ryan C, Bonnefous C, Govek S, Seiders TJ, Cosford NDP, Roppe J, Kamenecka T, Patel S, Gibson RE, Sanabria S, Riffel K, Eng W, King C, Yang X, Green MD, O'Malley SS, Hargreaves R, Burns HD. Synthesis, characterization, and first successful monkey imaging studies of metabotropic glutamate receptor subtype 5 (mGluR5) PET radiotracers. Synapse 2005; 56:205-16. [PMID: 15803497 DOI: 10.1002/syn.20147] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Three metabotropic glutamate receptor subtype 5 (mGluR5) PET tracers have been labeled with either carbon-11 or fluorine-18 and their in vitro and in vivo behavior in rhesus monkey has been characterized. Each of these tracers share the common features of high affinity for mGluR5 (0.08-0.23 nM vs. rat mGluR5) and moderate lipophilicity (log P 2.8-3.4). Compound 1b was synthesized using a Suzuki or Stille coupling reaction with [11C]MeI. Compounds 2b and 3b were synthesized by a SNAr reaction using a 3-chlorobenzonitrile precursor. Autoradiographic studies in rhesus monkey brain slices using 2b and 3b showed specific binding in cortex, caudate, putamen, amygdala, hippocampus, most thalamic nuclei, and lower binding in the cerebellum. PET imaging studies in monkey showed that all three tracers readily enter the brain and provide an mGluR5-specific signal in all gray matter regions, including the cerebellum. The specific signal observed in the cerebellum was confirmed by the autoradiographic studies and saturation binding experiments that showed tracer binding in the cerebellum of rhesus monkeys. In vitro metabolism studies using the unlabeled compounds showed that 1a, 2a, and 3a are metabolized slower by human liver microsomes than by monkey liver microsomes. In vivo metabolism studies showed 3b to be long-lived in rhesus plasma with only one other more polar metabolite observed.
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Affiliation(s)
- Terence G Hamill
- Merck Research Laboratories, Imaging Research Department, West Point, PA 19486, USA.
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Hu YZ, Wilson MH, Zong R, Bonnefous C, McMillin DR, Thummel RP. A luminescent Pt(ii) complex with a terpyridine-like ligand involving a six-membered chelate ring. Dalton Trans 2005:354-8. [PMID: 15616726 DOI: 10.1039/b415021j] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ligand 2-(8'-quinolinyl)-1,10-phenanthroline (1) was prepared in 79% yield by the Friedlander condensation of 8-amino-7-quinolinecarbaldehyde and 8-acetylquinoline. The complex [Pt(1)Cl]+ was prepared and compared with the isomeric 2-(2'-quinolinyl)-1,10-phenanthroline (2) complex. An X-ray analysis indicated that the six-membered chelate ring in the tridentate complex resulted in a relief of angle strain as well as some non-planarity in the bound ligand 1. The control system for photophysical studies is [Pt3Cl]+ where denotes 2-(2'-pyridyl)-1,10-phenanthroline. Relative to the complex of 3, in dichloromethane solution [Pt(1)Cl]+ exhibits noticeably higher energy charge-transfer absorption but slightly lower energy emission. The gap between the onset of absorption and emission is larger because the emission from [Pt(1)Cl]+ originates from a triplet excited state with substantial intra-ligand character. At room temperature in deoxygenated dichloromethane, [Pt(1)Cl]+ has an excited-state lifetime of 310 ns vs. 230 ns for [Pt(1)Cl]+. Within the series, [Pt(1)Cl]+ also exhibits the largest activation barrier for thermally induced quenching at 2730 cm(-1) in fluid dichloromethane solution. However, the barrier is only about 50% larger than that found for [Pt(1)Cl]+. There is reduced ring strain in [Pt(1)Cl]+, but inter-ligand steric interactions weaken the ligand field.
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Affiliation(s)
- Yi-Zhen Hu
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana, 47907-2084, USA
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Abstract
Difficulty in cyclometalating 1-(2'-quinolinyl)pyrene and 1,3-di-(2'-quinolinyl)pyrene with Ru(II) led to a more detailed study of the cyclometalation process. A series of 2-aryl-1,10-phenanthrolines, where aryl = phenyl, 2-naphthyl, 1-anthracenyl, and 1-pyrenyl, were treated with [Ru(tpy)Cl(3)] to provide either the N5Cl complex [Ru(tpy)(L)Cl](+) or this same material as a mixture with the N5C cyclometalated species [Ru(tpy)L](+). Steric effects appear to govern the ability of the ligand to attain the near planar conformation required for cyclometalation. The bridged ligand 3,1'-dimethylene-2-(2'-pyrenyl)-1,10-phenanthroline was prepared along with a quinoline analogue. The former species was found to cyclometalate at the C1 of pyrene and afford the N5Cl complex. Both the N5C (P2(1)/n (monoclinic), a = 28.1102(11), b = 8.4638(3), c = 31.2908(12) A, Z = 8) and N5Cl (P-1 (triclinic), a = 11.7235 (10), b = 14.5306(12), c = 14.5725(12) A, Z = 2) complexes were analyzed by X-ray crystallography, and the N5Cl species evidenced a congested environment for pyrene, which is apparently stabilized by pi stacking with tpy. Similar reactions with a series of three 3,2'-bridged derivatives of 2-phenyl-1,10-phenanthroline provide both N5Cl and cyclometalated products in proportions which support the importance of pi stacking. The electronic absorption spectra and redox potentials for these complexes evidence strong sigma donation by the cyclometalated ligand and an apparent insensitivity to the orthogonal 2-aryl group.
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Affiliation(s)
- C Bonnefous
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA
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