Bryan D. Anderson

Novel, potent and selective cyclin D1/CDK4 inhibitors: indolo[6,7-a]pyrrolo[3,4-c]carbazoles.

The synthesis and CDK inhibitory properties of a series of indolo[6,7-a]pyrrolo[3,4-c]carbazoles is reported. In addition to their potent CDK activity, the compounds display antiproliferative activity against two human cancer cell lines. These inhibitors also effect strong G1 arrest in these cell lines and inhibit Rb phosphorylation at Ser780 consistent with inhibition of cyclin D1/CDK4.

Optimization of a Dihydropyrrolopyrazole Series of Transforming Growth Factor-β Type I Receptor Kinase Domain Inhibitors: Discovery of an Orally Bioavailable Transforming Growth Factor-β Receptor Type I Inhibitor as Antitumor Agent

In our continuing effort to expand the SAR of the quinoline domain of dihydropyrrolopyrazole series, we have discovered compound 15d, which demonstrated the antitumor efficacy with oral bioavailability. This effort also demonstrated that the PK/PD in vivo target inhibition paradigm is an effective approach to assess potential for antitumor efficacy. The dihydropyrrolopyrazole inhibitor 15d (LY2109761) is representative of a novel series of antitumor agents.

Characterization of LY2228820 Dimesylate, a Potent and Selective Inhibitor of p38 MAPK with Antitumor Activity

p38α mitogen-activated protein kinase (MAPK) is activated in cancer cells in response to environmental factors, oncogenic stress, radiation, and chemotherapy. p38α MAPK phosphorylates a number of substrates, including MAPKAP-K2 (MK2), and regulates the production of cytokines in the tumor microenvironment, such as TNF-α, interleukin-1β (IL-1β), IL-6, and CXCL8 (IL-8). p38α MAPK is highly expressed in human cancers and may play a role in tumor growth, invasion, metastasis, and drug resistance. LY2228820 dimesylate (hereafter LY2228820), a trisubstituted imidazole derivative, is a potent and selective, ATP-competitive inhibitor of the α- and β-isoforms of p38 MAPK in vitro (IC50 = 5.3 and 3.2 nmol/L, respectively). In cell-based assays, LY2228820 potently and selectively inhibited phosphorylation of MK2 (Thr334) in anisomycin-stimulated HeLa cells (at 9.8 nmol/L by Western blot analysis) and anisomycin-induced mouse RAW264.7 macrophages (IC50 = 35.3 nmol/L) with no changes in phosphorylation of p38α MAPK, JNK, ERK1/2, c-Jun, ATF2, or c-Myc ≤ 10 μmol/L. LY2228820 also reduced TNF-α secretion by lipopolysaccharide/IFN-γ–stimulated macrophages (IC50 = 6.3 nmol/L). In mice transplanted with B16-F10 melanoma, tumor phospho-MK2 (p-MK2) was inhibited by LY2228820 in a dose-dependent manner [threshold effective dose (TED)70 = 11.2 mg/kg]. Significant target inhibition (>40% reduction in p-MK2) was maintained for 4 to 8 hours following a single 10 mg/kg oral dose. LY2228820 produced significant tumor growth delay in multiple in vivo cancer models (melanoma, non–small cell lung cancer, ovarian, glioma, myeloma, breast). In summary, LY2228820 is a p38 MAPK inhibitor, which has been optimized for potency, selectivity, drug-like properties (such as oral bioavailability), and efficacy in animal models of human cancer. Mol Cancer Ther; 13(2); 364–74. ©2013 AACR.

Abstract 4973: Discovery of LY3214996, a selective and novel ERK1/2 inhibitor with potent antitumor activities in cancer models with MAPK pathway alterations

The RAS/MAPK pathway is dysregulated in approximately 30% of human cancers, and the extracellular-signal-regulated kinases (ERK1 and ERK2) serves as key central nodes within this pathway. The feasibility and clinical impact of targeting the RAS/MAPK pathway has been demonstrated by the therapeutic success of BRAF and MEK inhibitors in BRAF V600E/K metastatic melanoma. However, resistance develops frequently through reactivation of the pathway. Therefore, simultaneous targeting of multiple effectors such as RAF, MEK and ERK in this pathway, offers a potential for enhanced efficacy while delaying and overcoming resistance. LY3214996 is a highly selective inhibitor of ERK1 and ERK2, with IC50 of 5 nM for both enzymes in biochemical assays. It potently inhibits cellular phospho-RSK1 in BRAF and RAS mutant cancer cell lines. In an unbiased tumor cell panel sensitivity profiling for inhibition of cell proliferation, tumor cells with MAPK pathway alterations including BRAF, NRAS or KRAS mutation are generally sensitivity to LY3214996. In tumor xenograft models, LY3214996 inhibits PD biomarker phospho-p90RSK1 in tumors and the PD effects are correlated with compound exposures and anti-tumor activities. LY3214996 shows either similar or superior anti-tumor activity as compared to other published ERK inhibitors in BRAF or RAS mutant cell lines and xenograft models. Oral administration of single-agent LY3214996 significantly inhibits tumor growth in vivo and is well tolerated in BRAF or NRAS mutant melanoma, BRAF or KRAS mutant colorectal, lung and pancreatic cancer xenografts or PDX models. Therefore, LY3214996 can be tailored for treatment of cancers with MAPK pathway alteration. In addition, LY3214996 has anti-tumor activity in a vemurafenib-resistant A375 melanoma xenograft model due to MAPK reactivation, may have potential for treatment of melanoma patients who have failed BRAF therapies. More importantly, LY3214996 can be combined with investigational and approved agents in preclinical models, particularly KRAS mutant models. Combination treatment of LY3214996 and CDK4/6 inhibitor abemaciclib was well tolerated and results in potent tumor growth inhibition or regression in multiple in vivo cancer models, including KRAS mutant colorectal and non-small cell lung cancers. Here, we first report the preclinical characterization of LY3214996, a novel small molecule ERK1/2 inhibitor currently in Phase I clinical trials in patients with advanced and metastatic cancers (NCT02857270). Citation Format: Shripad V. Bhagwat, William T. McMillen, Shufen Cai, Baohui Zhao, Matthew Whitesell, Lisa Kindler, Robert S. Flack, Wenjuan Wu, Karen Huss, Bryan Anderson, Xiu-Juan Yuan, Susan Jaken, Denis McCann, Brian Mathes, Andrew J. Dropsey, Jason Manro, Jennie Walgren, Eunice Yuen, Xueqian Gong, Michael J. Rodriguez, Jianping Huang, Ramon V. Tiu, Sajan Joseph, Sheng-Bin Peng. Discovery of LY3214996, a selective and novel ERK1/2 inhibitor with potent antitumor activities in cancer models with MAPK pathway alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4973. doi:10.1158/1538-7445.AM2017-4973

Preclinical assessment of galunisertib (LY2157299 monohydrate), a first-in-class transforming growth factor-β receptor type I inhibitor

Transforming growth factor-β (TGFβ) is an important driver of tumor growth via intrinsic and extrinsic mechanisms, and is therefore an attractive target for developing cancer therapeutics. Using preclinical models, we characterized the anti-tumor activity of a small molecule inhibitor of TGFβ receptor I (TGFβRI), galunisertib (LY2157299 monohydrate). Galunisertib demonstrated potent and selective inhibition of TGFβRI with corresponding inhibition of downstream signaling via inhibition of SMAD phosphorylation (pSMAD). Galunisertib also inhibited TGFβ-induced pSMAD in vivo, which enabled a pharmacokinetic/pharmacodynamic profile in Calu6 and EMT6-LM2 tumors. Galunisertib demonstrated anti-tumor activity including inhibition of tumor cell migration and mesenchymal phenotype, reversal of TGFβ-mediated immune-suppression, and tumor growth delay. A concentration-effect relationship was established with a dosing schedule to achieve the optimal level of target modulation. Finally, a rat model demonstrated a correlation between galunisertib-dependent inhibition of pSMAD in tumor tissues and in PBMCs, supporting the use of PBMCs for assessing pharmacodynamic effects. Galunisertib has been tested in several clinical studies with evidence of anti-tumor activity observed in subsets of patients. Here, we demonstrate that galunisertib inhibits a number of TGFβ-dependent functions leading to anti-tumor activity. The enhanced understanding of galunisertib provides rationale for further informed clinical development of TGFβ pathway inhibitors.

Abstract 955: LY3200882, a novel, highly selective TGFβRI small molecule inhibitor

The transforming growth factor β (TGFβ) signaling pathway is a pleiotropic cellular pathway that plays a critical role in cancer. In fact, aggressive tumors are typically associated with high ligand levels and thus associated with poor prognosis in various tumor types. Cancer cells use autocrine and paracrine TGFβ signaling to modulate tumor cells and the tumor microenvironment leading to a highly invasive and metastatic phenotype, inducing and increasing tumor vascularization, modulating the extracellular matrix in the stroma, and inhibiting immune surveillance and antitumor immunity. Clinical studies with galunisertib (aka LY2157299 monohydrate), a small molecule inhibitor targeting the TGFβ pathway, have provided proof of concept data supporting the role of TGFβ in cancer and the utility of targeting the TGFβ pathway. Here we describe the identification of LY3200882, a next generation small molecule inhibitor of TGF-β receptor type 1 (TGFβRI). The molecule is a potent, highly selective inhibitor of TGFβRI embodied in a structural platform with a synthetically scalable route. It is an ATP competitive inhibitor of the serine-threonine kinase domain of TGFβRI. Mechanism of action studies reveal revealed that LY3200882 inhibits various pro-tumorigenic activities. LY3200882 potently inhibits TGFβ mediated SMAD phosphorylation in vitro in tumor and immune cells and in vivo in subcutaneous tumors in a dose dependent fashion. In preclinical tumor models, LY3200882 showed potent anti-tumor activity in the orthotopic 4T1-LP model of triple negative breast cancer and this activity correlated with enhanced tumor infiltrating lymphocytes in the tumor microenvironment. Durable tumor regressions in the orthotopic 4T1-LP model were observed and rechallenge of congenic tumors resulted in complete rejection in all mice. In in vitro immune suppression assays, LY3200882 has shown the ability to rescue TGFβ1 suppressed or T regulatory cell suppressed naive T cell activity and restore proliferation. Therefore, LY3200882 shows promising activity as an immune modulatory agent. In addition, LY3200882 has shown anti-metastatic activity in vitro in migration assays as well as in vivo in an experimental metastasis tumor model (intravenous EMT6-LM2 model of triple negative breast cancer). Finally, LY3200882 shows combinatorial anti-tumor benefits with checkpoint inhibition (anti-PD-L1) in the syngeneic CT26 model. In conclusion, we have developed a novel potent and highly selective small molecule inhibitor of TGFβRI for the treatment of cancer. Citation Format: Huaxing Pei, Saravanan Parthasarathy, Sajan Joseph, William McMillen, Xiaohong Xu, Stephen Castaneda, Ivan Inigo, Karen Britt, Bryan Anderson, Gaiying Zhao, Scott Sawyer, Douglas Beight, Talbi Kaoudi, Chandrasekar Iyer, Huimin Bian, Amy Pappas, David Surguladze, David Schaer, Karim Benhadji, Michael Kalos, Kyla Driscoll. LY3200882, a novel, highly selective TGFβRI small molecule inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 955. doi:10.1158/1538-7445.AM2017-955

Abstract 3231: Identifying high quality, potent and selective pyrimidinylthienopyrrolone inhibitors of ERK1/2 kinase: LY3214996

The ERK/MAPK pathway plays a central role in the regulation of critical cellular processes and is activated in more than 30% of human cancers. While targeting upstream nodes with RAF and MEK inhibitors has proven effective clinically, resistance frequently develops through reactivation of the pathway. ERK inhibitors have the potential to address resistance caused by ERK reactivation. Herein, a potent, selective small molecule ERK1/2 inhibitor is described. LY3214996 possesses an optimal balance of potency (hERK1 IC50 5 nM, hERK2 IC50 5nM, pRSK IC50 0.43 µM), solubility (FaSSIF solubility at pH 6.5 0.133 µM), PK properties (dog, AUCoral 23800 nM*hr, CL 12.1 mL/min/kg, bioavailability 75.4%), IVTI (TED50 =16 mg/kg pRSK1) and demonstrated significant in vivo efficacy in several human cancer xenograft models. LY3214996 is currently undergoing early clinical evaluation. Citation Format: Gaiying Zhao, William T. McMillen, Shufen Cai, Baohui Zhao, Matthew Whitesell, Wenjuan Wu, Karen Huss, Bryan Anderson, Xiu-Juan Yuan, Susan Jaken, Lisa Kindler, Robert S. Flack, Denis McCann, Brian Mathes, Andrew J. Dropsey, Jennie Walgren, Eunice Yuen, Jason Manro, Xueqian Gong, Guillermo Cortez, Johnathan McLean, Michael J. Rodriguez, Ramon V. Tiu, Shripad V. Bhagwat, Sajan Joseph. Identifying high quality, potent and selective pyrimidinylthienopyrrolone inhibitors of ERK1/2 kinase: LY3214996 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3231. doi:10.1158/1538-7445.AM2017-3231

Abstract B235: Characterization of LY2228820 dimesylate, a potent and selective inhibitor of p38 MAPK with antitumor activity.

p38α mitogen-activated protein kinase (MAPK) is activated by cancer cells in response to environmental factors, such as oncogenic stress, radiation, and chemotherapy. p38α MAPK phosphorylates a number of substrates, including MAPKAP-K2 (MK2), and regulates the production/message stability of cytokines produced in the tumor microenvironment, such as TNFα, IL1 β, IL-6 and IL-8. p38α MAPK is activated and highly expressed in human cancers and may play a role in tumor growth, invasion and metastasis. LY2228820 dimesylate is a tri-substituted imidazole derivative that is a potent and ATP-competitive inhibitor of the α and β isoforms of p38 MAPK in vitro (IC50 = 5.3 nM and 3.2 nM, respectively). This compound displays > 1000-fold selectivity for p38α MAPK versus 179 other kinases tested (including p38δ and γ isoforms). In cell-based assays, LY2228820 dimesylate also potently and selectively inhibits phosphorylation of MK2 (Thr334) in TNFα-stimulated HeLa cells (IC50 = 8.1 nM) and anisomycin-induced mouse RAW264.7 macrophages (IC50 = 35.3 nM) with no changes in phosphorylation of p38α MAPK, JNK, ERK1/2, c-jun, ATF2 or cMyc at concentrations up to 10μM. LY2228820 dimesylate also reduces TNFα secretion by LPS/IFNγ-stimulated macrophages (IC50 = 6.3 nM). In mice transplanted with B16-F10 melanomas, phospho-MK2 was effectively inhibited by LY2228820 dimesylate in tumors in a dose-dependent manner (TMED70 = 19.4 mg/kg). Significant target inhibition (>40% inhibition of phospho-MK2) was maintained for approx. 4–8hrs following a single 10mg/kg oral dose. In a broad range of xenograft models (A-549 NSCLC, SK-OV-3 Ovarian, U-87MG Glioma, MDA-MB-468 Breast), LY2228820 dimesylate demonstrates significant tumor growth delay. In summary, LY2228820 dimesylate is a novel, potent and selective inhibitor of p38 MAPK with anti-tumor activity. Further studies are ongoing to determine its molecular mechanism(s) of action, potential for combination with standard-of-care agents, and potential clinical activity. 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 B235.