The cell cycle is an evolutionarily conserved process necessary for mammalian cell growth and development. Because cell-cycle aberrations are a hallmark of cancer, this process has been the target of ...anti-cancer therapeutics for decades. However, despite numerous clinical trials, cell-cycle-targeting agents have generally failed in the clinic. This review briefly examines past cell-cycle-targeted therapeutics and outlines how experience with these agents has provided valuable insight to refine and improve anti-mitotic strategies. An overview of emerging anti-mitotic approaches with promising pre-clinical results is provided, and the concept of exploiting the genomic instability of tumor cells through therapeutic inhibition of mitotic checkpoints is discussed. We believe this strategy has a high likelihood of success given its potential to enhance therapeutic index by targeting tumor-specific vulnerabilities. This reasoning stimulated our development of novel inhibitors targeting the critical regulators of genomic stability and the mitotic checkpoint: AURKA, PLK4, and Mps1/TTK.
Dominguez-Brauer et al. review the therapeutic potential of exploiting the genomic instability of tumor cells by inhibiting mitotic checkpoints as a strategy to selectively target tumor-specific vulnerabilities.
PLK4 was identified as a promising therapeutic target through a systematic approach that combined RNAi screening with gene expression analysis in human breast cancers and cell lines. A drug discovery ...program culminated in CFI-400945, a potent and selective PLK4 inhibitor. Cancer cells treated with CFI-400945 exhibit effects consistent with PLK4 kinase inhibition, including dysregulated centriole duplication, mitotic defects, and cell death. Oral administration of CFI-400945 to mice bearing human cancer xenografts results in the significant inhibition of tumor growth at doses that are well tolerated. Increased antitumor activity in vivo was observed in PTEN-deficient compared to PTEN wild-type cancer xenografts. Our findings provide a rationale for the clinical evaluation of CFI-400945 in patients with solid tumors, in particular those deficient in PTEN.
•CFI-400945 is a PLK4 small molecule inhibitor with significant anticancer activity•CFI-400945 causes dysregulated centriole duplication, mitotic errors, and cell death•CFI-400945 may represent a therapeutic option for a range of solid tumors
Mason et al. show that PLK4 is a potential therapeutic target in human cancers. Mason et al. further identify a PLK4 inhibitor, CFI-400945, and demonstrate its potential as a clinically useful cancer therapeutic.
Loss of cell-cycle control is a hallmark of human cancer. Cell-cycle checkpoints are essential for maintaining genome integrity and balanced growth and division. They are specifically deregulated in ...cancer cells and contain regulators that represent potential therapeutic targets. Monopolar spindle 1 (Mps1; also known as TTK protein kinase) is a core component of the spindle assembly checkpoint (SAC), a genome-surveillance mechanism that is important for cell survival, and has emerged as a candidate target for anticancer therapy. Here, we report the cellular and antitumor effects of CFI-402257, a potent (Mps1 K
i = 0.09 ± 0.02 nM; cellular Mps1 EC50 = 6.5 ± 0.5 nM), highly selective, and orally active small-molecule inhibitor of Mps1 that was identified through a drug-discovery program. Human cancer cells treated with CFI-402257 exhibit effects consistent with Mps1 kinase inhibition, specifically SAC inactivation, leading to chromosome missegregation, aneuploidy, and ultimately cell death. Oral administration of CFI-402257 in monotherapy or in combination with an anti-programmed cell death 1 (PD-1) antibody in mouse models of human cancer results in inhibition of tumor growth at doses that are well-tolerated. Our findings provide a rationale for the clinical evaluation of CFI-402257 in patients with solid tumors.
Myeloid cells contribute to tumor progression, but how the constellation of receptors they express regulates their functions within the tumor microenvironment (TME) is unclear. We demonstrate that ...Fcmr (Toso), the putative receptor for soluble IgM, modulates myeloid cell responses to cancer. In a syngeneic melanoma model, Fcmr ablation in myeloid cells suppressed tumor growth and extended mouse survival. Fcmr deficiency increased myeloid cell population density in this malignancy and enhanced anti-tumor immunity. Single-cell RNA sequencing of Fcmr-deficient tumor-associated mononuclear phagocytes revealed a unique subset with enhanced antigen processing/presenting properties. Conversely, Fcmr activity negatively regulated the activation and migratory capacity of myeloid cells in vivo, and T cell activation by bone marrow-derived dendritic cells in vitro. Therapeutic targeting of Fcmr during oncogenesis decreased tumor growth when used as a single agent or in combination with anti-PD-1. Thus, Fcmr regulates myeloid cell activation within the TME and may be a potential therapeutic target.
The acetamido and carboxamido substituted 3-(1H-indazol-3-yl)benzenesulfonamides are potent TTK inhibitors. However, they display modest ability to attenuate cancer cell growth; their ...physicochemical properties, and attendant pharmacokinetic parameters, are not drug-like. By eliminating the polar 3-sulfonamide group and grafting a heterocycle at the 4 position of the phenyl ring, potent inhibitors with oral exposure were obtained. An X-ray cocrystal structure and a refined binding model allowed for a structure guided approach. Systematic optimization resulted in novel TTK inhibitors, namely 3-(4-(heterocyclyl)phenyl)-1H-indazole-5-carboxamides. Compounds incorporating the 3-hydroxy-8-azabicyclo3.2.1octan-8-yl bicyclic system were potent (TTK IC50 < 10 nM, HCT116 GI50 < 0.1 μM), displayed low off-target activity (>500×), and microsomal stability (T 1/2 > 30 min). A subset was tested in rodent PK and mouse xenograft models of human cancer. Compound 75 (CFI-401870) recapitulated the phenotype of TTK RNAi, demonstrated in vivo tumor growth inhibition upon oral dosing, and was selected for preclinical evaluation.
The endogenous metabolite of estradiol, 2-Methoxyestradiol (2ME2), is an antimitotic and antiangiogenic cancer drug candidate that also exhibits disease-modifying activity in animal models of ...rheumatoid arthritis (RA). We found that 2ME2 dramatically suppresses development of mouse experimental autoimmune encephalomyelitis (EAE), a rodent model of multiple sclerosis (MS). 2ME2 inhibits in vitro lymphocyte activation, cytokine production, and proliferation in a dose-dependent fashion. 2ME2 treatment of lymphocytes specifically reduced the nuclear translocation and transcriptional activity of nuclear factor of activated T-cells (NFAT) c1, whereas NF-κB and activator protein 1 (AP-1) activation were not adversely affected. We therefore propose that 2ME2 attenuates EAE through disruption of the NFAT pathway and subsequent lymphocyte activation. By extension, our findings provide a molecular rationale for the use of 2ME2 as a tolerable oral immunomodulatory agent for the treatment of autoimmune disorders such as MS in humans.
The Aurora kinases are a family of conserved serine-threonine kinases with key roles in mitotic cell division. As with other promising anticancer targets, patient selection strategies to identify a ...responsive subtype will likely be required for successful clinical development of Aurora kinase inhibitors. The purpose of this study was to evaluate the antitumor activity of the Aurora and angiogenic kinase inhibitor ENMD-2076 against preclinical models of breast cancer with identification of candidate predictive biomarkers.
Twenty-nine breast cancer cell lines were exposed to ENMD-2076 and the effects on proliferation, apoptosis, and cell-cycle distribution were evaluated. In vitro activity was confirmed in MDA-MB-468 and MDA-MB-231 triple-negative breast cancer xenografts. Systematic gene expression analysis was used to identify up- and downregulated pathways in the sensitive and resistant cell lines, including within the triple-negative breast cancer subset.
ENMD-2076 showed antiproliferative activity against breast cancer cell lines, with more robust activity against cell lines lacking estrogen receptor expression and those without increased HER2 expression. Within the triple-negative breast cancer subset, cell lines with a p53 mutation and increased p53 expression were more sensitive to the cytotoxic and proapoptotic effects of ENMD-2076 exposure than cell lines with decreased p53 expression.
ENMD-2076 exhibited robust anticancer activity against models of triple-negative breast cancer and the candidate predictive biomarkers identified in this study may be useful in selecting patients for Aurora kinase inhibitors in the future.
Abstract Purpose The purpose was to assess the activity and side effect profile of ENMD-2076, an oral anti-angiogenic and anti-proliferative kinase inhibitor, in platinum-resistant recurrent ...epithelial ovarian cancer (EOC), fallopian tube or peritoneal cancer. Archival tumour tissue was obtained for correlative analyses. Experimental design This was an open-label single-arm Phase II study of single agent ENMD-2076 taken daily orally (PO). The primary objective was to determine the progression free survival (PFS) rate at 6 months of ENMD-2076 in platinum-resistant cancer based on RECIST v1.1. Secondary objectives included response rate (RR), duration of response, overall survival (OS) and safety. An exploratory analysis of archival tissue for mitotic index and angiogenesis was conducted in an attempt to identify a sensitive or resistant patient phenotype. Results 64 patients were enrolled, and the PFS rate at 6 months was 22% with a median time to progression of 3.6 months. The median number of prior regimens was 2. The most common adverse events were fatigue, hypertension and diarrhoea with the most common Grade 3/4 events being hypertension and fatigue. None of the markers of mitotic index or angiogenesis evaluated in the archival tissue samples were predictive of greater benefit or resistance to ENMD-2076 treatment. Conclusions ENMD-2076 has activity in platinum-resistant ovarian cancer, and observed toxicities were similar to other PO kinase inhibitors. Additional studies with ENMD-2076 are warranted, especially in combination with active chemotherapeutic agents in platinum-resistant patients. Further work to determine appropriate biomarkers for ENMD-2076 should be incorporated into new clinical studies.
Summary
ENMD‐2076 is a novel, orally‐active molecule that has been shown to have significant activity against aurora and multiple receptor tyrosine kinases. We investigated the activity of ENMD‐2076 ...against multiple myeloma (MM) cells in vitro and in vivo. ENMD‐2076 showed significant cytotoxicity against MM cell lines and primary cells, with minimal cytotoxicity to haematopoietic progenitors. ENMD‐2076 inhibited the phosphoinositide 3‐kinase/AKT pathway and downregulated survivin and X‐linked inhibitor of apoptosis as early as 6 h after treatment. With longer treatment (24–48 h), ENMD‐2076 also inhibited aurora A and B kinases, and induced G2/M cell cycle arrest. In non‐obese diabetic/severe combined immunodeficient mice implanted with H929 human plasmacytoma xenografts, oral treatment with ENMD‐2076 (50, 100, 200 mg/kg per day) resulted in a dose‐dependent inhibition of tumour growth. Immunohistochemical staining of excised tumours showed significant reduction in phospho‐Histone 3 (pH3), Ki‐67, and angiogenesis, and also a significant increase in cleaved caspase‐3 at all dose levels compared to tumours from vehicle‐treated mice. In addition, a significant reduction in p‐FGFR3 was observed on Western blot. ENMD‐2076 shows significant activity against MM cells in vitro and in vivo, and acts on several pathways important for myeloma cell growth and survival. These results provide preclinical rationale for clinical investigation of ENMD‐2076 in MM.
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