Polo-like Kinase Research Articles

Application of PLK1 and HOXA13 Gene Expression Levels in Urine in the Diagnosis of Non-muscle Invasive Bladder Cancer.

Bladder cancer is the most common urinary tract neoplasm, affecting many people annually. Current diagnostic and surveillance methods for bladder cancer are frequently invasive and lack sensitivity and specificity. This study aimed to develop an accurate and non-invasive urine-based gene expression assay, including fibroblast growth factor receptor 3 (FGFR3), homeobox A13 (HOXA13), and polo-like kinase 1 (PLK1), to diagnose non-muscle-invasive bladder cancer (NMIBC) at stages Ta and T1. The samples were acquired from 62 patients with NMIBC, 31 control individuals, and 31 patients with non-cancerous genitourinary tract diseases. The expression levels of three relevant genes were determined using quantitative RT-PCR. In addition, the sensitivity and specificity of the data for these genes were computed. Our results showed that PLK1, HOXA13, and FGFR3 expressions of genes were significantly elevated in patients compared to the control groups (p = 0.0001; p = 0.039). The sensitivity and specificity for the FGFR3 gene were 55% and 76%, respectively (p = 0.39). These parameters for HOXA13 were 100% and 93% (p = 0.0001) and for PLK1 were 100% and 86% (p = 0.0001) for diagnosing and monitoring NMIBC. HOXA13 and PLK 1 exhibited adequate specificity and sensitivity for diagnosis. The results of this research showed that despite the higher expression of these genes in urine, only HOXA13 and PLK1 had sufficient and proper specificity and sensitivity, so the urinary expression of these two genes can be used in future studies for diagnosis and monitoring in cancer bladder.

Abstract PO2-04-09: Combination of the PLK1 Inhibitor Onvansertib and the PI3Kα Inhibitor Alpelisib Overcomes Palbociclib Resistance in PIK3CA-mutated HR+ Breast Cancer

Abstract In the 1st line setting of hormone receptor-positive HER2 negative (HR+/HER2-) metastatic breast cancer, cyclin dependent kinase 4 and 6 (CDK4/6) inhibitors (palbociclib, abemaciclib and ribociclib) are typically used in combination with endocrine therapy. Though initially effective, acquired resistance to either CDK4/6 inhibitors or endocrine therapy eventually leads to disease relapse in most patients. Activating mutations in PIK3CA, the gene encoding alpha catalytic subunit of phosphatidylinositol-4,5-bisphosphat 3-kinase (PI3K) are found in approximately 40% of HR+ breast cancer patients and have been implicated in mediating resistance to CDK4/6 inhibitors. The PI3Kα inhibitor alpelisib is currently approved for PI3KCA-mutant HR+ breast cancer after progression on CDK4/6 inhibitors. However, drug-associated resistance mechanisms may limit its clinical benefit. Synergistic combination therapies have the potential to improve efficacy and overcome resistance mechanisms. Polo-like kinase 1 (PLK1) is a serine-threonine-protein kinase, key cell cycle regulator that controls G2/M entry and mitotic progression, and that has been shown to mediate resistance to palbociclib in HR+ breast cancer. Onvansertib is an oral and highly specific PLK1 inhibitor currently on clinical development in solid tumors and hematological malignancies. Here we evaluated the potential of onvansertib to increase the activity of alpelisib in PIK3CA-mutant HR+ breast cancer preclinical models. The combination of onvansertib and alpelisib synergistically inhibited cell viability and/or colony formation in three PI3KCA-mutant HR+ breast cancer cell lines, MCF-7 (PIK3CA E545K), EFM-19 (PIK3CA H1047L), and T-47D (PIK3CA 1047R). A significant increase in apoptosis was observed in cells treated with the combination compared to either agent alone. We next tested the combination of onvansertib and alpelisib in patient-derived xenograft (PDX) models. For this purpose, palbociclib-resistant PIK3CA-mutant HR+ breast cancer PDXs were established from primary breast tumor (PDX HBCx-86, PIK3CA E545K) or from metastatic bone biopsies of patients who had progressed on endocrine therapy plus palbociclib (HBCx-180, PIK3CA H1047R) or on PI3Kα inhibitor (HBCx-134palboR31, PIK3CA H1047R). PDX tumors were grafted subcutaneously in nude mice and mice were treated with vehicle, onvansertib (45 mg/kg, oral, 5 days a week), alpelisib (25mg/kg, oral, 5 days a week) or the combination. The combination was well tolerated and showed superior anti-tumor activity than the single agents in the 3 PDX models. In the HBCx-86 PDX, although none of the single agents showed activity, the combination induced potent tumor growth inhibition. In the metastasis-derived PDX HBCx-134palboR31, the combination treatment induced pronounced tumor regression in 62% of mice (5/8), with complete response in 25% (2/8), while mice treated with the single agents showed tumor progression. Finally, in the HBCx-180 PDX, established from a patient with primary resistance to palbociclib, the efficacy of the combination was greater and more durable, with significant survival advantage, compared to the monotherapies. Collectively, our preclinical findings suggest that co-targeting PLK1 and PI3Kα with onvansertib and alpelisib respectively, may constitute a promising therapeutic combination strategy for patients with PIK3CA-mutant HR+ breast cancer failing to respond to first-line standard of care therapies. Citation Format: Sreeja Sreekumar, Pierre Painsec, Davis Klein, Dalia Gonzalez, Laura Sourd, Elodie Montaudon, Tod Smeal, Elisabetta Marangoni, Maya Ridinger. Combination of the PLK1 Inhibitor Onvansertib and the PI3Kα Inhibitor Alpelisib Overcomes Palbociclib Resistance in PIK3CA-mutated HR+ Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-04-09.

Abstract PO1-04-14: PLK1 Inhibitor Onvansertib Extends the Response and Overcomes Resistance to Paclitaxel in Palbociclib-resistant HR+ Breast Cancer Patient-derived Xenografts

Abstract Paclitaxel is a first-line chemotherapy for hormone receptor positive (HR+) metastatic breast cancer patients after progression on a combination of endocrine and CDK4/6 inhibitor therapy. Response rate to paclitaxel ranges between 20-40%, and most patients progress due to intrinsic or acquired resistance, leaving them with limited treatment choices. Therapeutic strategies to overcome paclitaxel resistance and extend its clinical benefit are urgently needed. Paclitaxel-resistant tumors have increased expression of polo-like kinase 1 (PLK1), a serine-threonine-protein kinase that regulates mitosis and cell cycle progression. PLK1 has also been shown to mediate resistance to CDK4/6 inhibitor palbociclib in HR+ breast cancer. Onvansertib is an orally bioavailable, highly potent, and selective PLK1 inhibitor in clinical development. Onvansertib exhibited synergy in vitro and showed potent anti-tumor activity in vivo in combination with paclitaxel in ovarian cancer and triple negative breast cancer (TNBC) preclinical models. A phase 1b/2 clinical trial is ongoing to evaluate the safety and efficacy of onvansertib plus paclitaxel in advanced TNBC (NCT05383196). Here we investigated whether the potential of onvansertib and paclitaxel combination could be extended to HR+ breast cancer. Co-treatment with onvansertib and paclitaxel synergistically inhibited the viability of HR+ breast cancer cell lines (MCF-7, T-47D, EFM-19, CAMA-1, ZR-75-1). Compared to the single agents, the combination induced increased apoptosis. The combination was further tested in vivo in patient-derived xenograft (PDX) models. To this end, six HR+ breast cancer PDXs with intrinsic or acquired resistance to palbociclib were established from primary breast tumors (n=1) or metastatic bone biopsies (n=5). The PDX tumors were engrafted subcutaneously in nude mice and the effect of onvansertib (45 mg/kg, oral, 5 days a week) and paclitaxel (15-25mg/kg, IP, once a week) was investigated as monotherapy and in combination. The combination of onvansertib and paclitaxel was tolerated with minimal toxicity and showed enhanced anti-tumor activity compared to either agent alone in all 6 PDX models. Paclitaxel and onvansertib monotherapies had little to no anti-tumor activity in 4 out of 6 PDX models (HBCx124palboR25, HBCx-139 palboR5, HBCx-202 and HBCx-131). Importantly, the combination of onvansertib and paclitaxel induced strong anti-tumor activity in these 4 models. Tumor regression was observed in the 2 PDX models with acquired resistance to palbociclib, HBCx-124palboR25 and HBCx-139palboR5, with 62% (5/8 mice) and 54% (6/11 mice) complete response rates, respectively. The combination showed tumor stasis in HBCx-131 and induced tumor regression in HBCx-202, established from patient resistant to palbociclib. In 2 of the 6 PDXs, paclitaxel exhibited anti-tumor activity, inducing tumor regression in HBCx-137paboR26 and tumor stasis in HBCx-86. In comparison, the combination of onvansertib and paclitaxel had greater activity, inducing tumor regression in both models with a higher rate of complete response than the monotherapy. Complete response rates for paclitaxel versus the combination were 62% and 100% in the HBCx-137palboR26 model and 0% and 67% in the HBCx-86 model. Notably, the antitumor activity of the onvansertib and paclitaxel combination was very durable, showing a robust delay in tumor relapse after stopping therapy. Together, our data strongly support that combining paclitaxel with the PLK1 inhibitor onvansertib extends its benefit and overcomes paclitaxel resistance, and represents a promising therapeutic strategy for HR+ breast cancer patients after progression on a combination of endocrine and CDK4/6 inhibitor therapy. Citation Format: Maya Ridinger, Pierre Painsec, Sreeja Sreekumar, Dalia Gonzalez, Davis Klein, Laura Sourd, Elodie Montaudon, Paul Cottu, Tod Smeal, Elisabetta Marangoni. PLK1 Inhibitor Onvansertib Extends the Response and Overcomes Resistance to Paclitaxel in Palbociclib-resistant HR+ Breast Cancer Patient-derived Xenografts [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-04-14.

Exploring Novel PLK1 Inhibitors based on Computational Studies of 2,4-Diarylaminopyrimidine Derivatives

Background: Polo-like kinase 1 (PLK1) is an important target for anti-cancer drugs. A series of novel 2,4-diarylaminopyrimidine derivatives (DAPDs) as PLK1 inhibitors (PLKIs) with remarkable activities have been reported recently. Methods: A systemically computational study was performed on these DAPDs, including threedimensional quantitative structure-activity relationship (3D-QSAR) modeling, molecular docking, and molecular dynamics (MD) simulation. Results: The constructed 3D-QSAR models exhibited reliable predictability with satisfactory validation parameters. The dockings revealed the binding modes of DAPDs in PLK1 protein, and two key residue, Cys133 and Phe183, could interact with DAPDs by hydrogen bonds and π-π stacking, which might be significant for the activity of these PLKIs. Eight compounds with higher predicted activity than the most active DAPD-compound (16) were designed based on the 3D-QSAR models. These newly designed compounds also exhibited higher docking scores than compound 16 in the binding pocket of PLK1. The ADME predictions and MD simulations further indicated that two hit compounds with reasonable pharmacokinetics properties could stably bind with PLK1 and have the potential to become novel PLKIs. Conclusion: Two newly designed compounds might have the potential to be novel PLKIs. These results might provide important information for the design and development of novel PLKIs.

PLK1-activating IFI16-STING-TBK1 pathway induces apoptosis of intestinal epithelial cells in patients with intestinal Behçet's syndrome.

Inflammatory signals from immunological cells may cause damage to intestinal epithelial cells (IECs), resulting in intestinal inflammation and tissue impairment. Interferon-γ-inducible protein 16 (IFI16) was reported to be involved in the pathogenesis of Behçet's syndrome (BS). This study aimed to investigate how inflammatory cytokines released by immunological cells and IFI16 participate in the pathogenesis of intestinal BS. RNA sequencing and real-time quantitative PCR (qPCR) showed that the positive regulation of tumor necrosis factor-α (TNF-α) production in peripheral blood mononuclear cells (PBMCs) of intestinal BS patients may be related to the upregulation of polo like kinase 1 (PLK1) in PBMCs (P = 0.012). The plasma TNF-α protein level in intestinal BS was significantly higher than in healthy controls (HCs; P = 0.009). PBMCs of intestinal BS patients and HCs were co-cultured with human normal IECs (NCM460) to explore the interaction between immunological cells and IECs. Using IFI16 knockdown, PBMC-NCM460 co-culture, TNF-α neutralizing monoclonal antibody (mAb), stimulator of interferon genes (STING) agonist 2'3'-cGAMP, and the PLK1 inhibitor SBE 13 HCL, we found that PLK1 promotes the secretion of TNF-α from PBMCs of intestinal BS patients, which causes overexpression of IFI16 and induces apoptosis of IECs via the STING-TBK1 pathway. The expressions of IFI16, TNF-α, cleaved caspase 3, phosphorylated STING (pSTING) and phosphorylated tank binding kinase 1 (pTBK1) in the intestinal ulcer tissue of BS patients were significantly higher than that of HCs (all P < 0.05). PLK1 in PBMCs of intestinal BS patients increased TNF-α secretion, inducing IEC apoptosis via activation of the IFI16-STING-TBK1 pathway. PLK1 and the IFI16-STING-TBK1 pathway may be new therapeutic targets for intestinal BS.

Molecular docking and dynamics studies to identify novel active compounds targeting potential breast cancer receptor proteins from an indigenous herb Euphorbia thymifolia Linn

Background Breast cancer has become the most prevalent disease and its incidence has almost doubled in the Indian population. This increased burden demands new targeted therapies with novel compounds either synthetically produced or derived from indigenous plants, which could be a promising approach for the development of drugs. Euphorbia thymifolia L is a widely growing tropical herb that has been reported to have various ethnopharmacological properties, including anticancer properties. Therefore, the aim of the present study was to screen the phytoconstituents and identify the active compounds present in the methanolic extract of E. thymifolia (ME.ET) as ligands to inhibit potential protein targets implicated in breast cancer using an In-silico approach. Methods ME.ET was subjected to GC-MS analysis to screen the phytoconstituents, and the identified compounds were docked with protein targets such as extracellular signal-regulated kinases (ERK1), a serine/threonine kinase-1(AKT1), human epidermal growth factor 2 (HER2), estrogen receptor (ER), maternal embryonic leucine zipper kinase (MELK), polo-like kinase-1(PLK1), and protein tyrosine kinase (PTK6). Compounds with good docking scores were further subjected to dynamic studies to understand the protein ligand binding stability, ligand pathway calculation, and molecular mechanics energies combined with Poisson-Boltzmann (MM/PBSA) calculations using the Schrodinger suite. Results GC-MS analysis revealed the presence of 245 phytoconstituents, 219 of which were unique. When subjected to docking, these phytocompounds, namely 3,6,9,12-tetraoxatetradecane-1,14-diyl dibenzoate (TTDB) and succinic acid, 2-(dimethylamino) ethyl 4-isopropylphenyl ester (SADPE), showed good docking scores. Molecular dynamics studies showed a high affinity and low binding energy for TTDB with HER2, ERK1, and SADPE with ER. Conclusions Hence, in this study, we identified two lead compounds in E.thymifolia linn. Further invitro and invivo anticancer studies can be performed to confirm these results and to understand the molecular mechanism by which they exhibit anticancer activity against breast cancer.

Identification of naphthalimide-derivatives as novel PBD-targeted polo-like kinase 1 inhibitors with efficacy in drug-resistant lung cancer cells

Targeting polo-box domain (PBD) small molecule for polo-like kinase 1 (PLK1) inhibition is a viable alternative to target kinase domain (KD), which could avoid pan-selectivity and dose-limiting toxicity of ATP-competitive inhibitors. However, their efficacy in these settings is still low and inaccessible to clinical requirement. Herein, we utilized a structure-based high-throughput virtual screen to find novel chemical scaffold capable of inhibiting PLK1 via targeting PBD and identified an initial hit molecule compound 1a. Based on the lead compound 1a, a structural optimization approach was carried out and several series of derivatives with naphthalimide structural motif were synthesized. Compound 4Bb was identified as a new potent PLK1 inhibitor with a KD value of 0.29 μM. 4Bb could target PLK1 PBD to inhibit PLK1 activity and subsequently suppress the interaction of PLK1 with protein regulator of cytokinesis 1 (PRC1), finally leading to mitotic catastrophe in drug-resistant lung cancer cells. Furthermore, 4Bb could undergo nucleophilic substitution with the thiol group of glutathione (GSH) to disturb the redox homeostasis through exhausting GSH. By regulating cell cycle machinery and increasing cellular oxidative stress, 4Bb exhibited potent cytotoxicity to multiple cancer cells and drug-resistant cancer cells. Subcutaneous and oral administration of 4Bb could effectively inhibit the growth of drug-resistant tumors in vivo, doubling the survival time of tumor bearing mice without side effects in normal tissues. Thus, our study offers an orally-available, structurally-novel PLK1 inhibitor for drug-resistant lung cancer therapy.

An orchestra of machine learning methods reveals landmarks in single-cell data exemplified with aging fibroblasts.

In this work, a Python framework for characteristic feature extraction is developed and applied to gene expression data of human fibroblasts. Unlabeled feature selection objectively determines groups and minimal gene sets separating groups. ML explainability methods transform the features correlating with phenotypic differences into causal reasoning, supported by further pipeline and visualization tools, allowing user knowledge to boost causal reasoning. The purpose of the framework is to identify characteristic features that are causally related to phenotypic differences of single cells. The pipeline consists of several data science methods enriched with purposeful visualization of the intermediate results in order to check them systematically and infuse the domain knowledge about the investigated process. A specific focus is to extract a small but meaningful set of genes to facilitate causal reasoning for the phenotypic differences. One application could be drug target identification. For this purpose, the framework follows different steps: feature reduction (PFA), low dimensional embedding (UMAP), clustering ((H)DBSCAN), feature correlation (chi-square, mutual information), ML validation and explainability (SHAP, tree explainer). The pipeline is validated by identifying and correctly separating signature genes associated with aging in fibroblasts from single-cell gene expression measurements: PLK3, polo-like protein kinase 3; CCDC88A, Coiled-Coil Domain Containing 88A; STAT3, signal transducer and activator of transcription-3; ZNF7, Zinc Finger Protein 7; SLC24A2, solute carrier family 24 member 2 and lncRNA RP11-372K14.2. The code for the preprocessing step can be found in the GitHub repository https://github.com/AC-PHD/NoLabelPFA, along with the characteristic feature extraction https://github.com/LauritzR/characteristic-feature-extraction.

Proteasome activation is critical for cell death induced by inhibitors of polo-like kinase 1 (PLK1) in multiple cancers

Inhibitors of polo-like kinase (PLK) are currently being evaluated as anticancer drugs. However, the molecular mechanism of PLK inhibitor-induced cell death is not fully understood. In this study, we found that GW843682X and BI2536, two inhibitors of PLK1, significantly induced cell death in multiple type cells. The induction of cell death was related to the preferring expression of PLK1. However, in human umbilical vascular endothelial cells (HUVEC) and human colorectal carcinoma cells, which expressed higher levels of both PLK1 and PLK2, PLK1 inhibitors induced very low levels of cell death. Clinical analysis reveals PLK1 presence in 26 of 30 NPC tumor tissues. In in vivo NPC lung metastasis nude mouse models, PLK1 inhibitors decreased NPC progress. Mechanistically, the PLK1 inhibitor did not activate p53, and the cell death was not reversed by p53 inhibition. Moreover, PLK1 inhibitor-induced cell death was PARP- and caspase-independent. Although PLK1 inhibitors induced down-regulation of calpain inhibitor calpastatin and calpain was activated by PLK1 inhibition, calpain blocking did not reverse cell death induced by PLK1 inhibitors, suggesting the non-involvement of calpain. Surprisingly, we found that PLK1 inhibitors induced the activation of proteasome, and the treatment of cells with PLK1 inhibitors reduced the levels of ubiquitinated proteins. And proteasome inhibitors reversed cell death induced by PLK1 inhibitors in various cell types in which PLK1 was preferentially expressed. Moreover, PLK1 inhibition reversed the degradation of proteins including p53, caspase 8, PARP and calpastatin. These results suggest that the activation of proteasome is critical for cell death induced by PLK1 inhibition.

Nardilysin-regulated scission mechanism activates polo-like kinase 3 to suppress the development of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) develops through step-wise genetic and molecular alterations including Kras mutation and inactivation of various apoptotic pathways. Here, we find that development of apoptotic resistance and metastasis of KrasG12D-driven PDAC in mice is accelerated by deleting Plk3, explaining the often-reduced Plk3 expression in human PDAC. Importantly, a 41-kDa Plk3 (p41Plk3) that contains the entire kinase domain at the N-terminus (1-353 aa) is activated by scission of the precursor p72Plk3 at Arg354 by metalloendopeptidase nardilysin (NRDC), and the resulting p32Plk3 C-terminal Polo-box domain (PBD) is removed by proteasome degradation, preventing the inhibition of p41Plk3 by PBD. We find that p41Plk3 is the activated form of Plk3 that regulates a feed-forward mechanism to promote apoptosis and suppress PDAC and metastasis. p41Plk3 phosphorylates c-Fos on Thr164, which in turn induces expression of Plk3 and pro-apoptotic genes. These findings uncover an NRDC-regulated post-translational mechanism that activates Plk3, establishing a prototypic regulation by scission mechanism.

Abstract LB225: Regulation of breast cancer stem cell identity by PLK1 and FOXC2

Abstract One of the main drivers for the drastic reduction in survival rates caused by metastatic breast cancer is attributed to Epithelial-to-Mesenchymal Transition (EMT). During embryonic development and wound healing, EMT plays a vital role and during cancer pathogenesis, cancer cells reactivate this program to gain plasticity, migration, and invasion promoting metastasis. In addition, EMT also plays a crucial role in generating a subpopulation of highly resilient tumor cells known as cancer stem cells (CSCs). Moreover, following conventional treatment, residual tumor cells that remain after treatment tend to exhibit CSC properties. EMT-induced cancer stem cells exhibit heightened plasticity and stemness, significantly fueling the metastatic spread of cancer and enhancing the endurance and adaptability throughout the process of metastasis. Thus, understanding the molecular intricacies governing stem cell properties holds immense potential for developing targeted therapies to target metastasis and the development of resistance to treatments. To further elucidate EMT-induced cancer stem cell generation, our lab has demonstrated that the Polo-like kinase 1 (PLK1), an important G2/M regulator, plays an important role in the generation of CSCs through Forkhead box protein C2 (FOXC2). Most importantly, we have shown that the FOXC2 transcription factor, known to be crucial in embryonic development, now has emerging roles in metastatic cancer progression. FOXC2 is positioned at the center of the complex network of signal transduction pathways and functions downstream of most EMT-inducing transcription factors. FOXC2 is necessary for the acquisition and maintenance of stem cell property. In addition, we found that phosphorylation of FOXC2 by PLK1 stabilizes, and inhibition of PLK1 causes a decrease in FOXC2 and stemness in cancer cells. This led us to hypothesize that EMT-induced CSC generation is driven by the PLK1-FOXC2 axis. By expressing phosphomimetic and non-phosphorylatable FOXC2 mutants in breast cancer cell lines, we show that PLK1 phosphorylation is necessary for gaining stemness and an increase in symmetric self-renewal type of stem cell division. Evidence will be presented as to how we are targeting the PLK1-FOXC2 axis to make tumors sensitive to standard-of-care treatments. Citation Format: Joanna Joyce Maddela, Maria Castaneda, Petra den Hollander, Nick Kuburich, Sendurai Mani. Regulation of breast cancer stem cell identity by PLK1 and FOXC2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB225.

Abstract CT275: A phase 2, randomized, open-label study of onvansertib in combination with standard-of-care (SoC) versus SoC alone for first-line treatment of RAS-mutant metastatic colorectal cancer (mCRC)

Abstract Background: Chemotherapy in combination with bevacizumab (Bev) has been a standard first-line treatment for RAS-mutated mCRC patients for the last 2 decades. The prognosis of these patients remains poor. Onvansertib is an orally available, highly potent, and selective inhibitor of Polo-like kinase 1 (PLK1), currently in clinical development. In a Phase 1b/2 study, onvansertib in combination with FOLFIRI + Bev demonstrated safety and promising efficacy in the second-line treatment of KRAS-mutated mCRC patients (NCT03829410). A subgroup analysis showed that patients not exposed to Bev (Bev-naïve) in the first-line setting had superior clinical benefit compared to Bev-exposed patients. Based on this data, we propose to investigate the combination of onvansertib with SoC (chemo + Bev) in the first-line treatment of RAS-mutated, Bev-naïve mCRC patients. Methods: This exploratory Phase 2, open-label, randomized study is designed to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of 2 doses of onvansertib (20 mg and 30 mg) in combination with SoC (FOLFIRI + Bev or FOLFOX + Bev) versus SoC alone in patients with RAS-mutated metastatic and unresectable CRC in the first-line setting. Eligible participants must have histologically confirmed mCRC, KRAS or NRAS mutation, no previous systemic therapy in the metastatic setting, ECOG performance status of 0 or 1, measurable disease as defined per RECIST v1.1. Exclusion criteria include patients with BRAF-V600 mutations or microsatellite instability high/deficient mismatch repair, prior treatment with a VEGF inhibitor, previous oxaliplatin treatment within 12 months prior to randomization. The primary endpoint is objective response as determined according to RECIST v1.1 by an independent central review. Key secondary endpoints include progression-free survival and duration of response per independent central review. The study will enroll approximately 90 patients. Each patient will be randomized to be treated with onvansertib (20 mg or 30 mg) + SoC or SoC alone. The enrollment period for this study is approximately 12 months. Patients will be followed for overall survival for up to 1 year after the end of treatment. Trial is open and recruiting as of November 2023. This trial is registered as NCT06106308. Citation Format: Heinz-Josef Lenz, Benjamin Kuritzky, Anu Thummala, Stephan Kendall, Ravindranath Patel, Sreenivasa R. Chandana, Alisha H. Bent, Nancy Sherman, Ramanand Arun Subramanian, Fairooz Kabbinavar, Joel Randolph Hecht. A phase 2, randomized, open-label study of onvansertib in combination with standard-of-care (SoC) versus SoC alone for first-line treatment of RAS-mutant metastatic colorectal cancer (mCRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT275.

Abstract CT195: First-in-human phase 1 study of WEE1 inhibitor APR-1051 in patients with advanced solid tumors harboring cancer-associated gene alterations

Abstract Background: WEE1 tyrosine kinase plays a key role in cell cycle regulation and DNA damage responses, acting as a principal gatekeeper of the G1-S and G2-M cell cycle checkpoints. Thus, inhibition of WEE1 can result in high cyclin-dependent kinase 1 and 2 activities, leading to aberrant cell cycle progression. Increasing premature entry into mitosis and subsequent apoptosis via WEE1 inhibition is one potential approach to killing cancer cells effectively. APR-1051 is an orally bioavailable, highly potent, small molecule inhibitor of WEE1 that has demonstrated in vivo anti-proliferative activity in multiple cancer cell lines and high selectivity for WEE1 versus polo-like kinases 1, 2, and 3. Increased selectivity for WEE1 may reduce the myelosuppressive toxicity (e.g., limiting Grade 3 toxicities) reported with other WEE1 inhibitors. Methods: The primary aim of this multi-center, open-label Phase I study is to characterize the safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD)/maximum administered dose (MAD) and recommended Phase 2 dose (RP2D) of APR-1051 in patients with advanced solid tumors harboring cancer-associated gene alterations. Secondary objectives include evaluating the pharmacokinetic (PK) properties of APR-1051, assessing the effect of food on its PK, and its preliminary efficacy per RECIST version 1.1. The exploratory objective is to assess the pharmacodynamic effects of APR-1051. For dose escalation, an accelerated titration followed by a BOIN design will be utilized to determine the MAD/MTD. Upon completion of the dose escalation, two suitable doses and schedules of single-agent APR-1051 will be determined for further investigation in dose selection optimization. Key inclusion criteria are age at least 18 years with advanced solid tumor and cancer-associated gene alterations (e.g., amplification/overexpression of CCNE1 or CCNE2, deleterious mutations in FBXW7 or PPP2R1A), ECOG PS 0 or 1, and adequate organ function. Key exclusion criteria are cancer therapy within 3 weeks or at least 5 half-lives, prior radiation therapy at the target lesion except if evidence of disease progression, unresolved therapy-related AEs, investigational agent within 5 half-lives or 30 days of study drug, prior WEE1 inhibitor, CNS metastases or unstable involvement, secondary malignancies that are active and/or require therapy, and concomitant moderate/strong inhibitors/inducers of CYP3A4/5, MDR1, or BCRP. Up to 79 patients will be enrolled at 3 to 5 sites in the United States. Citation Format: Timothy A. Yap, Crystal Miller, David Stenehjem, Eric J. Brown, Mike Carleton, Nadeem Q. Mirza. First-in-human phase 1 study of WEE1 inhibitor APR-1051 in patients with advanced solid tumors harboring cancer-associated gene alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT195.

Design of novel PLK4 inhibitors as TRIM37-amplified breast cancer drugs using 3D-QSAR, molecular docking, and molecular dynamics simulation methods

ABSTRACT A mitosis-associated protein kinase, serine/threonine protein kinase polo-like kinase 4 (PLK4) is thought to be a promising target for the therapy of tripartite motif-containing 37 (TRIM37)-amplified breast cancer. The study's dataset for 3D-QSAR modelling included 37 derivatives of pyrazolo[3,4-d] pyrimidines, and the outcomes showed strong statistical significance (COMFA: q 2 =  0.744, r 2 =  0.997, r pred 2  = 0.702; CoMSIA: q 2 = 0.652, r 2 = 0.991, r pred 2  = 0.722). Findings from an analysis of isopotential maps using the COMFA and COMSIA models, ten novel small molecule inhibitors with potentially high activities were designed. To investigate the processes of interactions among the inhibitor molecules along with the receptor proteins, molecular docking and simulations of molecular dynamics were utilised. According to the results, the amino acids Cys92, Glu96, Asn94, and Asn103 may form hydrogen bonds with the ligands, which could enhance the small molecules’ inhibitory effect. Furthermore, MMPBSA calculations revealed that the newly created compounds have a higher binding affinity to the receptor proteins. Ultimately, these compounds also demonstrated good AMDET properties in pharmacokinetic parameter tests, indicating their promise as innovative medications for the management of breast cancer. These results offer the theoretical direction required to support the creation of effective PLK4 inhibitors.

Pan-cancer analysis of polo-like kinase family genes reveals polo-like kinase 1 as a novel oncogene in kidney renal papillary cell carcinoma

BackgroundPolo-like kinases (PLKs) are a kinase class of serine/threonine with five members that play crucial roles in cell cycle regulation. However, their biological functions, regulation, and expression remain unclear. This study revealed the molecular properties, oncogenic role, and clinical significance of PLK genes in pan-cancers, particularly in kidney renal papillary cell carcinoma (KIRP). MethodsWe evaluated the mutation landscape, expression level, and prognostic values of PLK genes using bioinformatics analyses and explored the association between the expression level of PLK genes and tumor microenvironment (TME), immune subtype, cancer immunotherapy, tumor stemness, and drug sensitivity. Finally, we verified the prognostic value in patients with KIRP through univariate and multivariate analyses and nomogram construction. ResultsPLK genes are extensively altered in pan-cancer, which may contribute to tumorigenesis. These genes are aberrantly expressed in some types of cancer, with PLK1 being overexpressed in 31 cancers. PLK expression is closely associated with the prognosis of various cancers. The expression level of PLK genes is related with sensitivity to diverse drugs and cancer immunity as well as cancer immunotherapy. Importantly, we verified that PLK1 was overexpressed in KIRP tissues and could be an unfavorable prognostic biomarker in patients with KIRP. Hence, PLK1 may serve as an oncogenic gene in KIRP and should be explored in future studies. ConclusionsOur study comprehensively reports the molecular characteristics and biological functions of PLK family gens across human cancers and recommends further investigation of these genes as potential biomarkers and therapeutic targets, especially in KIRP.

Design, Synthesis and Anticancer Activity of Substituted 1, 3-Thiazolidin-4-One Derivatives

Background: Cancer is the global cause of death worldwide. Anticancer drug development is the need in today’s scenario. Thiazolidine is the nucleus that shows several pharmacological activities like anticancer, anti-inflammatory, antioxidant, antibacterial, antifungal, antidiabetic, antihyperlipidemic, and antiarthritic activity. In the present work molecular docking Glide module (Schrodinger Inc., USA) has been used for ligand docking against the Polo-like kinase-1. The series of substituted 3-Benzothiazol-2-yl-2-phenyl)-thiazolidin-4-ones were synthesized by the microwave-assisted synthesis system (CEM, USA) and characterized by melting point, FT-IR, 1H NMR, 13C NMR, and HR-MS analysis. Results: Molecular docking studies shows good docking score as well as interactions. Among the synthesized compounds, BG2 had the highest docking score of -8.381, followed by BG8 (-8.19) and BG1 (-8.156). All the newly synthesized compounds were examined for their in vitro anticancer activity against breast cancer cell line MCF-7 by Sulforhodamine B (SRB) assay. Conclusion: BG1, BG2, BG3, BG4, BG5, BG8, BG9, BG10, BG11, BG12, and BG13 (GI50: &lt;80 µg/ml) exhibited significant cell growth inhibitory activity. These results indicate that compounds showing in-vitro activity by molecular docking studies and SRB assay could be lead compounds for further development of anticancer agents and suitable candidates for in-vivo anticancer activity.

Control of cell proliferation by memories of mitosis.

Mitotic duration is tightly constrained, and extended mitosis is characteristic of problematic cells prone to chromosome missegregation and genomic instability. We show here that mitotic extension leads to the formation of p53-binding protein 1 (53BP1)-ubiquitin-specific protease 28 (USP28)-p53 protein complexes that are transmitted to, and stably retained by, daughter cells. Complexes assembled through a Polo-like kinase 1-dependent mechanism during extended mitosis and elicited a p53 response in G1 that prevented the proliferation of the progeny of cells that experienced an approximately threefold extended mitosis or successive less extended mitoses. The ability to monitor mitotic extension was lost in p53-mutant cancers and some p53-wild-type (p53-WT) cancers, consistent with classification of TP53BP1 and USP28 as tumor suppressors. Cancers retaining the ability to monitor mitotic extension exhibited sensitivity to antimitotic agents.

Centrosomes and associated proteins in pathogenesis and treatment of breast cancer.

Breast cancer is the most prevalent malignancy among women worldwide. Despite significant advances in treatment, it remains one of the leading causes of female mortality. The inability to effectively treat advanced and/or treatment-resistant breast cancer demonstrates the need to develop novel treatment strategies and targeted therapies. Centrosomes and their associated proteins have been shown to play key roles in the pathogenesis of breast cancer and thus represent promising targets for drug and biomarker development. Centrosomes are fundamental cellular structures in the mammalian cell that are responsible for error-free execution of cell division. Centrosome amplification and aberrant expression of its associated proteins such as Polo-like kinases (PLKs), Aurora kinases (AURKs) and Cyclin-dependent kinases (CDKs) have been observed in various cancers, including breast cancer. These aberrations in breast cancer are thought to cause improper chromosomal segregation during mitosis, leading to chromosomal instability and uncontrolled cell division, allowing cancer cells to acquire new genetic changes that result in evasion of cell death and the promotion of tumor formation. Various chemical compounds developed against PLKs and AURKs have shown meaningful antitumorigenic effects in breast cancer cells in vitro and in vivo. The mechanism of action of these inhibitors is likely related to exacerbation of numerical genomic instability, such as aneuploidy or polyploidy. Furthermore, growing evidence demonstrates enhanced antitumorigenic effects when inhibitors specific to centrosome-associated proteins are used in combination with either radiation or chemotherapy drugs in breast cancer. This review focuses on the current knowledge regarding the roles of centrosome and centrosome-associated proteins in breast cancer pathogenesis and their utility as novel targets for breast cancer treatment.

A polo-like kinase 1 inhibitor enhances erastin sensitivity in head and neck squamous cell carcinoma cells in vitro.

Polo-like kinase 1 (PLK1) is a critical therapeutic target in the treatment of head and neck squamous cell carcinoma (HNSCC). The objective of this study was to investigate the therapeutic effect of the combination of BI 2536, a PLK1 inhibitor, and erastin, a ferroptosis inducer, in HNSCC. The proliferation, invasion, and migration abilities of Tu177 and FaDu cells upon exposure to BI 2536 and erastin, used in combination or alone, were tested. Fe2+, glutathione (GSH), and malondialdehyde (MDA) detection kits were used to determine whether the addition of BI 2536 enhanced the accumulation of Fe2+ and MDA, along with the depletion of GSH. Quantitative real-time PCR, western blot analyses were performed to investigate whether BI 2536 further altered the mRNA and expression level of ferroptosis genes. Furthermore, si PLK1 was used to investigate whether targeting PLK1 gene promoted erastin-induced ferroptosis. The combination of BI 2536 and erastin exerted a stronger cytotoxicity than treatment with a single agent. Compared with erastin treatment alone, the combination of BI 2536 and erastin lowered the ability of tumor cells to self-clone, invade, and migrate. BI 2536 enhanced the accumulation of Fe2+ and MDA, and the depletion of GSH. BI 2536 increased erastin-induced changes in ferroptosis-related gene mRNA and expression. Importantly, targeting PKL1 enhanced the anti-cancer effect of erastin. BI 2536 enhanced the sensitivity of HNSCC cells to erastin, which provides a new perspective for cancer treatment.

Abstract 3482: Single-cell transcriptome analysis reveals that PLK4 signature genes are highly associated with cancer proliferation and hotspot mutations in non-small cell lung cancer (NSCLC)

Abstract Background: Polo-like kinase 4 (PLK4) is a member of the polo-like kinase family known for its precise regulation during the cell cycle and its key role in centriole duplication, which is essential for proper cell division. Dysregulation of PLK4 is associated with abnormal centriole number, genomic instability and cancer development. In our previous study, we proposed PLK4 as a potential therapeutic target and biomarker for LUAD patients with TP53 mutations by bulk RNA-seq analysis and confirmed its association with drug resistance. In this study, we analyzed the expression of PLK4 and its association with cell cycle at the cellular level by scRNA-seq in NSCLC data. Methods: In a previous study, we analyzed NSCLC data from The Cancer Genome Atlas (TCGA) database using the UCSC Xena data portal. In this study, we analyzed E-MTAB-6653 dataset from the single cell expression atlas(https://www.ebi.ac.uk/gxa/sc/home). Results: In the previous study, we demonstrated that PLK4 expression is higher in primary tumors compared to normal tissues in NSCLC. Higher PLK4 expression in patients is associated with an unfavorable prognosis. Using genes highly correlated with PLK4, we confirmed a significant association between PLK4 and TP53 mutation by statistical analysis. Using the Drug Gene Interaction database, we observed an association between the drug resistance-related genes PBK and BIRC5 with PLK4, and these genes were also correlated with TP53 mutation. In this study, we investigated the association between PLK4 and the cell cycle using single cell RNA-seq. First, we performed data pre-processing to selectively isolate NSCLC cells. Using a set of 87 PLK4 signature genes obtained from previous research, we stratified the samples into PLK4 high and low groups based on the expression of these genes. We then analyzed cell cycle related genes in both groups and observed a higher expression of G2/M phase related genes in the PLK4 high group compared to the PLK4 low group. We also examined the expression of PLK4 signature genes based on pathological differences and found higher expression in tumor tissue compared to normal tissue. There was also an increasing expression gradient from the tumor margin to the tumor core. Finally, using Gene Ontology analysis of both groups, we confirmed the upregulation of genes associated with transcription and translation, as indicated by the GO terms obtained. Conclusion: In a previous study, the association between PLK4 expression, TP53 mutation and drug resistance was identified by bulk RNA-seq. In the current study, we used single cell RNA-seq to verify the correlation between PLK4 and cell cycle in NSCLC. In addition, we observed that the expression of PLK4 signature genes increased towards the tumor core based on pathological differences. Citation Format: Youngtaek Kim, Joon Yeon Hwang, YoungJoon Park, Dong Kwon Kim, Kwangmin Na, Seul Lee, Sujeong Baek, Seong-san Kang, Seung Min Yang, Mi Hyun Kim, Heekyung Han, Chai Young Lee, Yu Jin Han, Min Hee Hong, Jii Bum Lee, Sun Min Lim, Kyoung-Ho Pyo, Byoung Chul Cho. Single-cell transcriptome analysis reveals that PLK4 signature genes are highly associated with cancer proliferation and hotspot mutations in non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3482.