Cyclin-dependent Kinase Pathway Research Articles

Rationale for the advancement of PI3K pathway inhibitors for personalized chordoma therapy.

Chordomas are rare and serious tumors with few effective treatments outside of aggressive surgery and radiation. Targeted therapies may present a more effective option for a subset of patients with lesions possessing certain genetic biomarkers. A small molecule inhibitor library was tested in patient-derived UM-Chor1 cells to identify targeted therapies with potential efficacy. Targeted exome sequencing of UM-Chor1 and UM-Chor2 cells was performed to investigate genetic aberrations in relevant pathways. Chordoma cell lines were treated with inhibitors of the phosphotidylinositol 3-kinase (PI3K), epidermal growth factor receptor (EGFR), and cyclin dependent kinase (CDK) pathways, and responses were determined using resazurin cell viability assays, Annexin V apoptosis assays, and western blotting. Pan-PI3K inhibitor BKM120 was also tested in five chordoma xenograft models. Unbiased small molecule profiling nominated PI3K-AKT-mTOR pathway inhibitors as a promising therapy in chordoma, and genetic analyses of UM-Chor1 and UM-Chor2 cell lines revealed aberrations in PTEN, EGFR, and CDKN2A. Treatment of UM-Chor1 and UM-Chor2 with targeted PI3K, EGFR, and CDK inhibitors inhibited growth and proliferation and induced apoptosis more robustly than imatinib, a currently used chordoma therapy. Furthermore, BKM120 significantly inhibited tumor growth in a subset of the xenograft models tested. Targeted therapies, especially those inhibiting PI3K, display promising effects in multiple chordoma cell line and xenograft models. Nevertheless, the limited effects of PI3K, EGFR, and CDK targeting agents in other models reveal the presence of resistance mechanisms, which motivates future research to both identify biomarkers of response and develop combination therapies.

CMET-33. PHASE II STUDY OF PALBOCICLIB IN BRAIN METASTASES HARBORING CDK PATHWAY ALTERATIONS

Abstract BACKGROUND Up to 25% of all cancer patients will develop brain metastases and prognosis remains poor. In preclinical work, we discovered that more than 50% brain metastases genomically diverge from primary tumors and harbor alterations in genes involved with cell cycle regulation. We thus initiated a phase II study to evaluate the efficacy and safety of the cyclin dependent kinase (CDK) 4/6 inhibitor, palbociclib, in patients with recurrent brain metastases with alterations in the CDK pathway (NCT02896335). METHODS The primary endpoint of the trial is the rate of intracranial benefit (defined as CR, PR, or SD, per RANO) at 8 weeks after the start of palbociclib. A Simon two-stage design was used to compare the rate of intracranial benefit for a null rate of 10% against an alternative of 30%. Fifteen patients were to be enrolled in the first stage. If fewer than 2 responders were observed, then the study would stop for insufficient evidence of efficacy. If 6 or more responders were observed among the total of 30, this treatment regimen would be considered worthy of further study. CSF, blood samples and tumor samples were collected to elucidate the genomic determinants of response to CDK inhibitors in the brain. RESULTS A total of 14 patients have been accrued (5 with breast cancer, 4 with melanoma, 3 esophageal and 2 with non-small cell lung cancer) thus far. One or more grade-3 or higher adverse events at least possibly related to treatment were seen in six (42%) patients, the majority being hematologic toxicities. At the time of the data analysis, eight (57%) patients had achieved intracranial benefit. Therefore, the study met primary endpoint. CONCLUSIONS In this unique, genomically-guided brain metastasis trial, we demonstrate that the CDK 4/6 inhibitor, palbociclib, is well-tolerated and has activity in patients with brain metastases.

The cyclin‑dependent kinase pathway involving CDK1 is a potential therapeutic target for cholangiocarcinoma.

Cholangiocarcinoma is an aggressive malignancy with high mortality, and effective therapeutic agents for this cancer are limited. Cyclin‑dependent kinase (CDK) pathways are therapeutic targets for various types of cancers; however, their involvement in cholangiocarcinoma remains unclear. The present study examined the biological significance of CDK pathways in cholangiocarcinoma. An immunohistochemical analysis of cholangiocarcinoma tissue sections revealed the upregulated expression of phosphorylated cyclin‑dependent kinase 1 (p‑CDK1), p‑CDK2, cyclin B1, and cyclin E1 in carcinoma cells. The nuclear expression of p‑CDK1 and cyclin B1 was positively correlated with the presence of lymph node metastasis and the clinical stage, and p‑CDK1 expression was also associated with poor patient survival. The treatment of human cholangiocarcinoma cell lines (CCKS‑1, TFK‑1 and HUCCT‑1) with the multi‑CDK inhibitor roscovitine decreased p‑CDK1 expression, inhibited cell proliferation, arrested the cell cycle at the G1 or G2/M phase, and significantly inhibited carcinoma cell invasion. Invivo studies using a murine xenograft model revealed that an intraperitoneal injection of roscovitine significantly inhibited cholangiocarcinoma cell growth. Roscovitine induced apoptosis in cholangiocarcinoma cells invitro and invivo. These results demonstrated the potential of the CDK pathway involving CDK1 as a therapeutic target for cholangiocarcinoma. Furthermore, the immunohistochemical expression of p‑CDK1 may be a useful prognostic marker of cholangiocarcinoma.

Transcriptomic characterization of endometrial cancer in order to find new therapeutic targets.

e17113 Background: There are unmet needs for targeted therapy in Endometrial Cancer (EC). The integrated genomic characterization of EC provided insights into disease biology. Our primary objective is to identify potential actionable pathways to target therapeutically in EC according to the microsatellite status (microsatellite instability high = MSI-H, and microsatellite stable/microsatellite instability low = MSS/MSI-L). Methods: 375 RNAs from the genomic profile of EC within the TCGA database were used to perform RNA-seq analysis. We analyzed RNA-sequencing data with edgeR package to filter and normalize the data, followed by the limma package with its Voom method, linear modeling and empirical Bayes moderation to asses differential expression. Reactome FI Cytoscape app was used to perform pathway and network-based data analysis. Results: According to the microsatellite status, two groups were identified: Group 1 = MSI-H (127 patients) and Group 2 = MSS/MSI-L (248 patients). Significant expression differences were found in 2141 genes. In the Group 1 we identified 1194 genes overexpressed and 947 genes overexpressed in the Group 2. Group 1 includes genes associated with cell proliferation. Group 2 includes genes associated with genomic instability and apoptosis evasion (table 1). Conclusions: In EC patients, Cyclin-dependent kinase (CDK) pathways could be a potential therapeutic target, especially in patients with MSI-H tumors. Further studies are necessary in order to evaluate the activity of CDKs inhibitors in this population.[Table: see text]

Multiplatform profiling of pancreatic neuroendocrine tumors (PanNETs) identifies novel co-occurring pathogenic alterations and associations with clinicopathologic factors.

211 Background: We correlated genomic, proteomic, and molecular pathway alterations with clinicopathologic factors and identified novel co-occurring pathogenic alterations of potential clinical relevance to PanNET management through multi-omic profiling. Methods: Perthera, Inc. deploys an IRB-approved registry that was utilized in partnership with PanCAN’s “Know Your Tumor” program. PanNETs having undergone molecular profiling for precision matched therapeutic purposes were screened. We performed correlative analyses by pairwise comparisons between pathogenic alterations or altered molecular pathways and clinicopathologic variables. Hierarchical clustering was used to visualize associations. The Kaplan-Meier method was used to estimate overall survival (OS) and survival differences across variables were analyzed by the log-rank test. Results: We included 33 patients with predominantly locally advanced and metastatic PanNETs from 12/2014-1/2018. Chromatin remodeling pathway and MEN1 alterations by next-generation sequencing (NGS) were less associated with having high-grade PanNETs, while MEN1 alterations were also less associated with metastatic disease at diagnosis (all Fisher’s exact two-tailed p ≤ 0.05). Several molecular pathway or pathogenic alterations correlated with worse OS: DNA repair pathway (log-rank p = 0.0022), RB1 alterations by NGS (p = 0.018), and TP53 alterations by NGS (p = 0.01). There were several significant co-occurring alterations (Fisher’s exact p ≤ 0.05): ERCC1 expression by immunohistochemistry (IHC) and DAXX (NGS), RB1 (NGS) and DNA repair pathway (NGS), and TS (IHC) and cyclin-dependent kinase pathway (NGS). Having an altered chromatin remodeling pathway was less associated with having an altered receptor tyrosine kinase (RTK) signaling pathway (Fisher’s exact p ≤ 0.05). Conclusions: We identified several molecular signatures of potential clinical significance for therapeutic targeting and prognostication in PanNETs warranting prospective validation. Our findings are hypothesis generating and can inform larger molecular profiling efforts in PanNETs.

CDK4/6 inhibitors in breast cancer therapy: Current practice and future opportunities.

Dysregulation of the cyclin dependent kinase pathway in luminal breast cancer creates a new therapeutic opportunity for estrogen receptor positive breast cancer. Initial pan-CDK inhibitors were associated with extensive toxicities but in recent years, the development of potent specific CDK inhibitors with favorable tolerability has driven renewed interests in this class of targeted therapies. Palbociclib, ribociclib and abemaciclib are specific CDK4/6 inhibitors that have been approved by the U.S. Food and Drug Administration for use in combination with endocrine therapy for women with advanced hormone receptor positive breast cancer. These three anticancer therapeutics were approved based on progression free survival benefit seen on phase III trials with the most common grade 3 treatment-related side effects being neutropenia, fatigue, nausea and diarrhea. Except for estrogen receptor positivity, no biomarkers predictive of response to CDK4/6 inhibitors have been identified to date. Based on mechanistic insights here described, CDK4/6 inhibitors are currently being explored in combination with other agents, including targeted therapies, immunotherapy and chemotherapy.

Clinically Targetable Mutation Status Associated with Local Control Following Radiation Treatment for Brain Metastases

Brain metastases can harbor genetic mutations distinct from the primary tumor. It is unclear whether brain metastasis that contain clinically targetable mutations confer a local control benefit following radiation therapy (RT). Thus, we examined targetable mutation status within patients with whole-exome sequenced brain metastases that received radiation and assessed association with RT response. We retrospectively reviewed 58 patients with brain metastases that received RT from 2003-2014 and underwent whole-exome sequencing of matched brain metastases, primary tumor, and normal tissues. We have previously reported that whole exome analysis evaluated 95,431 gene alterations across our entire dataset and found 330 that met TARGET criteria as being clinically informative. Association between clinical factors, genetic alternation status, and local control was evaluated by Cox regression analysis. We performed Kaplan-Meier to assess local failure and overall survival based on presence of clinically targetable mutation status. 58 patients within our dataset received intracranial radiation therapy for brain metastases. The median follow-up was 16.5 months. Thirteen patients received SRS alone, 25 patients received WBRT alone, and 20 patients received SRS and WBRT. Forty-eight lesions were treated with SRS, 31 lesions (65%) were treated with single fraction (median dose 18 Gy, range 16-22 Gy) and 17 lesions were treated with a hypofractionated regimen (25 Gy in 5 fractions). The median dose for WBRT was 35 Gy in 2.5 Gy fractions (range 30-39 Gy). The most common tumor histologies were lung adenocarcinoma (N=22, 38%) and breast carcinoma (N=14, 24%). Patients were identified with brain metastases that contained a potentially favorable mutation status for treatment sensitivity to inhibitors for the cyclin-dependent kinase (CDK) pathway (n= 27), the PI3K/AKT/mTOR pathway (n= 26), the Her2/EGFR pathway (n= 18), and the MAPK pathway (n= 18). Patients that received targeted therapy (n=18) and immunotherapy (n=3) comprised 36% of the dataset. 19 radiographic local failure events were observed with a median time to failure of 9.2 months (range, 1-40 months). A unique clinically actionable mutation was observed in 16 of 58 (29%) of brain metastases not detected in the clinically sampled primary tumor. Clinically actionable mutation status is associated with local control following radiation therapy for brain metastases. Prospective trials involving patients with genetically characterized brain metastases treated with targeted therapeutic strategies in combination with radiation are needed.

Clinical Benefit in Response to Palbociclib Treatment in Refractory Uterine Leiomyosarcomas with a Common CDKN2A Alteration.

Uterine leiomyosarcoma (uLMS) responds poorly to conventional chemotherapeutic agents, and personalized therapies have yet to be systematically explored. Comprehensive genomic profiling (CGP) can identify therapeutic targets and provide insight into the biology of this highly aggressive tumor. We report a case of uLMS treated with the CGP-matched therapy palbociclib, a CDK4/6 inhibitor, with sustained clinical benefit in this rare and deadly malignancy. This study analyzed 279 clinically advanced/recurrent uLMS samples. Median patient age was 54 years (range, 23-83 years). DNA was extracted from 40 µm of formalin-fixed, paraffin-embedded sections, and CGP was performed on hybridization-captured, adaptor ligation-based libraries for up to 405 cancer-related genes plus introns from up to 31 genes frequently rearranged in cancer. Sequencing data were analyzed for base pair substitutions, insertions/deletions, copy number alterations, and rearrangements. CGP shows that 97.1% of uLMS harbor at least one alteration, and approximately 57% harbor alterations in one or more therapeutically targetable pathways. CDKN2A mutations that inactivate p16INK4a were identified in 11% of uLMS. We report the first demonstration of clinical benefit in response to palbociclib treatment for a uLMS patient with a CDKN2A mutation, resulting in disease stabilization and significant symptom reduction. A patient with uLMS harboring a CDKN2A mutation experienced clinical benefit from treatment with palbociclib, and genomic analysis of 279 uLMS samples revealed that 19% of patients had mutations affecting the cyclin-dependent kinase (CDK) pathway. These observations provide a rationale for a clinical trial investigating treatment with CDK pathway inhibitors for uLMS harboring relevant genomic alterations. The Oncologist 2017;22:416-421Implications for Practice: Comprehensive genomic profiling (CGP) of individuals with uterine leiomyosarcoma (uLMS) indicates that nearly 20% of patients may harbor a mutation affecting the cyclin-dependent kinase (CDK) pathway. The case presented demonstrates that a CDK inhibitory drug may provide clinical benefit to such individuals. Given the lack of curative therapies for uLMS, CGP could be performed on all cases of advanced uLMS and a CDK inhibitor could be recommended (preferably as part of a clinical trial) for individuals harboring a mutation in the CDK pathway.

Cyclin D1 expression in peripheral T-cell lymphomas

AbstractCyclin D1 is an important regulator of the cell cycle and overexpression of this protein by immunohistochemistry is characteristically seen in mantle cell lymphoma and other B-cell neoplasms. However, little is known about the expression of this protein in T-cell lymphomas. Cyclin-dependent kinase pathway inhibitors are in development, therefore identifying cyclin D1-positive T-cell lymphomas may provide a therapeutic target in a disease where novel treatments are urgently needed. We collected 200 peripheral T-cell lymphomas from three institutions including the following types of cases: 34 anaplastic large cell lymphoma, ALK+, 44 anaplastic large cell lymphoma, ALK negative, 68 peripheral T-cell lymphomas, not otherwise specified, 24 angioimmunoblastic T-cell lymphomas, 7 extranodal NK/T-cell lymphomas, 4 enteropathy associated T-cell lymphomas, 3 hepatosplenic T-cell lymphomas, 12 cutaneous T-cell lymphomas, and 4 large granular lymphocytic leukemias. Immunohistochemical stains for cyclin D1 protein (SP4 clone) were performed on paraffin-embedded tissue. In a subset of cases, IGH/CCND1 fluorescence in situ hybridization analysis was also performed. Cyclin D1 staining was predominantly seen in anaplastic large cell lymphoma, including 8 of 34 cases with ALK+ anaplastic large cell lymphoma (24%), and 3 of 44 cases of ALK-negative (7%) anaplastic large cell lymphoma. Three cases of peripheral T-cell lymphoma, not otherwise specified, were also positive (3/68, 4%). All other T-cell lymphomas were negative for cyclin D1. In four of the cyclin D1-positive T-cell lymphomas by immunohistochemistry, fluorescence in situ hybridization analysis was negative for IGH/CCND1 translocation or extra copies of the CCND1 gene. Cyclin D1 overexpression by immunohistochemistry is not limited to B-cell lymphomas and is also observed in some peripheral T-cell lymphomas, particularly in anaplastic large cell lymphoma, ALK+. Cyclin D1 expression was not associated with extra copies or translocation of the CCND1 gene. Cyclin D1 overexpression may be the result of a post-translational phenomenon and may represent a potential therapeutic target using agents that target the cyclin-dependent kinase pathway.

ERpS294 is a biomarker of ligand or mutational ERα activation and a breast cancer target for CDK2 inhibition.

ERα phosphorylation at hinge site S294 (pS294) was recently shown to be essential for ER-dependent gene transcription and mediated by an unknown cyclin-dependent kinase (CDK). This study was undertaken to identify the exact CDK pathway mediating pS294 formation, and to determine if this phosphorylation event occurs with, and can be targeted to treat, the ligand-independent growth of breast cancers expressing endocrine-refractory ESR1 mutations. Using a newly developed anti-pS294 monoclonal antibody, a combination of CDK specific siRNA knockdown studies and a broad panel of CDK selective inhibitors against ligand (E2)-stimulated MCF7 cells, we first identified CDK2 as the primary mediator of pS294 formation and showed that CDK2-selective inhibitors like Dinaciclib, but not CDK4/6 inhibitors like Palbociclib, can selectively prevent pS294 formation and repress ER-dependent gene expression. We then expressed the ER-activating mutations ERmut(Y537S) and ERmut(D538G) in MCF7 cells, and demonstrated their ability to induce ligand-independent and tamoxifen-resistant growth, associated with constitutive and CDK2-dependent pS294 expression. Following robust growth of E2-independent and TAM-resistant MCF7mutER(Y537S) tumors in vivo, nude mice were also treated with either Dinaciclib or Palbociclib at doses and injection schedules unable to retard tumor growth as single agents; the TAM plus Palbociclib combination arrested further tumor growth without affecting pS294 formation, while the TAM plus Dinaciclib combination produced tumor regression associated with loss of pS294 expression. These findings, and our proposed mechanistic model, provide new rationale for the clinical evaluation of CDK2 inhibitors given in combination with endocrine agents as a new treatment strategy against ESR1 mutation expressing breast cancers.

Clinical Implications of the Progression-Free Survival Endpoint for Treatment of Hormone Receptor-Positive Advanced Breast Cancer.

: Hormonal therapy for advanced breast cancer (ABC) has evolved significantly since the introduction of tamoxifen more than 40 years ago. The availability of selective antiestrogen therapies has further improved treatment options for women with hormone receptor-positive (HR+) ABC. However, with the development of resistance to hormonal therapies, a new treatment paradigm has emerged based on our understanding of biological pathways involved in HR+ breast cancer and mechanisms of resistance to hormonal therapy. Recent drug development efforts have focused on combining hormonal treatment with agents that target mammalian target of rapamycin serine-threonine kinases and cyclin-dependent kinases. In parallel with the evolution of hormonal and targeted therapies, our understanding of the utility of clinical endpoints has deepened. Progression-free survival (PFS) is a primary endpoint well-understood by clinicians and is increasingly accepted as a surrogate for overall survival (OS) by the U.S. Food and Drug Administration. Yet the perceived clinical benefit of PFS to patients is less well understood. Patients may not grasp the implications of prolonged PFS, highlighting the reality that patient preference in treatment selection encompasses factors that extend beyond drug activity. This presents an opportunity for clinicians to discuss PFS with patients in the context of their treatment plans, clinical outcomes, and quality-of-life measures. The objective of this review is to explore the clinical validity of the PFS and OS endpoints and the clinical relevance of PFS and OS to patients, especially in light of drivers that led to a range of treatment options for patients with HR+ ABC. Advances in drug development during the past two decades have provided numerous options for treatment of advanced breast cancer that include monotherapy with endocrine modulating agents and dual therapy that combines endocrine therapy with an inhibitor targeting the mammalian target of rapamycin serine-threonine kinase or cyclin-dependent kinase pathways known to be involved with resistance. Clinical trial endpoints for breast cancer have evolved as well. Communication of progression-free survival, overall survival, and other outcomes with patients should incorporate the context of the individual's treatment plan and include discussion of response rate, side effects, and quality of life.

Cyclin-dependent kinase pathways as targets for women's cancer treatment.

In this article, we not only review the preclinical and clinical studies of cyclin-dependent kinase (CDK) 4/6 inhibitors in breast cancer, liposarcoma, mantel cell lymphoma, melanoma and germ cell tumors, but also examine promising preclinical data in glioblastoma, renal and ovarian cancer models that may provide directions for future development. Targeting CDKs has been the focus of considerable basic science and clinical research. The CDK 4/6 inhibitors are a novel class of therapeutics that target the CDK 4/6 kinases that promote transition through the cell cycle. Currently, palbociclib (PD0332991, Pfizer), abemaciclib (LY2835219, Lilly) and ribociclib (LEE011, Novartis) are being investigated in clinical trials. These oral agents offer the hope of clinical efficacy in many tumor types, and have been associated with minimal toxicity. Amplification/overexpression of cyclin D, loss of CDKN2A (p16) and amplification/overexpression of CDK4 are proposed biomarkers of improved response to CDK4/6 inhibition. Palbociclib, abemaciclib and ribociclib have demonstrated very promising clinical activity in breast cancer, liposarcoma, mantel cell lymphoma and melanoma. Moreover, CDK4/6 inhibitors have shown promising preclinical activity in glioblastoma, renal and ovarian cancer models that may provide directions for their future clinical development. Further preclinical and clinical research is needed to better understand mechanisms of resistance and develop rational combination therapies with other targeted agents.

Inhibitors of the Cyclin-Dependent Kinase and PIM Kinase Pathways in the Treatment of Myeloma.

Multiple myeloma (MM) cells are characterized by genomic alternations that lead to increased cell proliferation and resistance to therapeutic interventions. Up-regulation of cyclins is a characteristic finding in a significant proportion of myeloma patients, mediated through a variety of mechanisms including chromosomal translocations. Cyclins and the cyclin-dependent kinases (CDKs) play a critical role in the cell proliferation seen in MM, especially in the high-risk disease. Given this, CDK inhibitors have been evaluated in this disease, and studies so far have led to a mixed picture. Recent studies with targeted CDK inhibitors have shown early promise, and trials of these drugs in combination with other myeloma drugs are ongoing. The malignant plasma cells in MM are highly dependent on the microenvironment for their growth and survival. Multiple signaling pathways have been found to mediate the interactions between the microenvironment and the plasma cells, whether mediated through cytokines or adhesion molecules. The PIM kinase pathway appears to play a major role in the myeloma cell survival, and PIM kinase inhibitors have shown efficacy in the laboratory, and a recent clinical trial also demonstrates important clinical activity.

Overcoming Endocrine Resistance in Hormone-Receptor Positive Advanced Breast Cancer-The Emerging Role of CDK4/6 Inhibitors.

Dysregulation of the cyclin D and cyclin-dependent kinase (CDK) pathway in cancer cells may inhibit senescence and promote cellular proliferation. By using various different mechanisms, malignant cells may increase cyclin D-dependent activity. The cyclin D-cyclin-dependent kinases 4 and 6 (CDK4/6)-retinoblastoma (Rb) pathway controls the cell cycle restriction point, and is commonly dysregulated in breast cancer; making it a rational target for anticancer therapy. To date, three oral highly selective cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) are in various stages of clinical development: PD0332991 (palbociclib), LEE011 (ribociclib) and LY2835219 (abemaciclib). Results from phase I, II and III trials in hormone-receptor (HR)-positive breast cancer have been encouraging, demonstrating convincing efficacy and a tolerable side-effect profile (mainly uncomplicated neutropenia). This article will review the preclinical and clinical development of the CDK4/6i, as well as reviewing the existing preclinical evidence regarding combination of these agents with chemotherapy and other targeted therapies. Future and ongoing clinical trials, which may expand the potential application of these agents, will also be discussed. In summary, CDK4/6i are exciting compounds which may change the therapeutic landscape of HR-positive breast cancer.

In Silico Identification and In Vitro and In Vivo Validation of Anti-Psychotic Drug Fluspirilene as a Potential CDK2 Inhibitor and a Candidate Anti-Cancer Drug.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. Surgical resection and conventional chemotherapy and radiotherapy ultimately fail due to tumor recurrence and HCC’s resistance. The development of novel therapies against HCC is thus urgently required. The cyclin-dependent kinase (CDK) pathways are important and well-established targets for cancer treatment. In particular, CDK2 is a key factor regulating the cell cycle G1 to S transition and a hallmark for cancers. In this study, we utilized our free and open-source protein-ligand docking software, idock, prospectively to identify potential CDK2 inhibitors from 4,311 FDA-approved small molecule drugs using a repurposing strategy and an ensemble docking methodology. Sorted by average idock score, nine compounds were purchased and tested in vitro. Among them, the anti-psychotic drug fluspirilene exhibited the highest anti-proliferative effect in human hepatocellular carcinoma HepG2 and Huh7 cells. We demonstrated for the first time that fluspirilene treatment significantly increased the percentage of cells in G1 phase, and decreased the expressions of CDK2, cyclin E and Rb, as well as the phosphorylations of CDK2 on Thr160 and Rb on Ser795. We also examined the anti-cancer effect of fluspirilene in vivo in BALB/C nude mice subcutaneously xenografted with human hepatocellular carcinoma Huh7 cells. Our results showed that oral fluspirilene treatment significantly inhibited tumor growth. Fluspirilene (15 mg/kg) exhibited strong anti-tumor activity, comparable to that of the leading cancer drug 5-fluorouracil (10 mg/kg). Moreover, the cocktail treatment with fluspirilene and 5-fluorouracil exhibited the highest therapeutic effect. These results suggested for the first time that fluspirilene is a potential CDK2 inhibitor and a candidate anti-cancer drug for the treatment of human hepatocellular carcinoma. In view of the fact that fluspirilene has a long history of safe human use, our discovery of fluspirilene as a potential anti-HCC drug may present an immediately applicable clinical therapy.

PI3K/APC pathway and cyclin-dependent kinase pathway to predict complete responders in CRC patients treated with ADAPT therapy.

e14642 Background: Recent studies have demonstrated that aspirin or selective COX-2 inhibitor improves overall survival in colorectal cancer (CRC) patients with PIK3CA mutations. However, routine use of anti-inflammatory agents in metastatic CRC patients remains controversial. We showed that addition of celecoxib, a selective COX-2 inhibitor coupled with capecitabine in a two step ADAPT (activating dormant tumor cells and potentiate targeting) therapy led to complete responses (CR) and long-term survival in patients with stage IV CRC. We sought to determine genetic aberrations and related pathways as predictor of CR to ADAPT therapy. Methods: We retrospectively reviewed 54 ADAPT therapy treated patients with stage IV CRC patients and tested for a panel of 199 cancer-related genes (UW Oncoplex) with Illumina deep sequencing platform between 2002-2012 including 11 CR for chemo, 12 CR for chemo-radiation, and surgical CR patients (none CR). The median overall survival in these CR patients had reached 92.7 mo...

The Role of CDK4/6 Inhibition in Breast Cancer.

Imbalance of the cyclin D and cyclin-dependent kinase (CDK) pathway in cancer cells may result in diversion away from a pathway to senescence and toward a more proliferative phenotype. Cancer cells may increase cyclin D-dependent activity through a variety of mechanisms. Therapeutic inhibition of CDKs in tumors to negate their evasion of growth suppressors has been identified as a key anticancer strategy. In this review, we outline the development of CDK inhibitory therapy in breast cancer, including the initial experience with the pan-CDK inhibitor flavopiridol and the next generation of oral highly selective CDK4 and CDK6 inhibitors PD0332991 (palbociclib), LEE011 (ribociclib), and LY2835219 (abemaciclib). Data from phase I and II studies in estrogen receptor-positive (ER+) breast cancer demonstrate promising efficacy with manageable toxic effects, chiefly neutropenia. We discuss these studies and the phase III studies that are accruing or nearing completion. We describe the application of such therapy to other breast cancer settings, including HER2-positive breast cancer and the adjuvant treatment of early breast cancer. We also discuss potential concerns surrounding the combination of CDK inhibitors with chemotherapy and their effects on repair of double-strand DNA breaks in cancer cells. Oral highly selective CDK inhibitors show great promise in improving the outcomes of patients with ER+ breast cancer, although caution must apply to their combination with other agents and in the early breast cancer setting.

High nuclear/cytoplasmic ratio of Cdk1 expression predicts poor prognosis in colorectal cancer patients.

BackgroundCdk1 (cyclin-dependent kinase 1) is critical regulator of the G2-M checkpoint. Cyclin-dependent kinase pathways are considered possible targets for cancer treatment; however, the prognostic role of Cdk1 in colorectal cancer is still controversial. Therefore, we attempted to determine the impact of Cdk1 on the clinical outcome of colorectal cancer patients to further identify its role in colorectal cancer.MethodsCdk1 immunoreactivity was analyzed by immunohistochemistry (IHC) in 164 cancer specimens from primary colorectal cancer patients. The medium follow-up time after surgery was 3.7 years (range: 0.01 to 13.10 years). The prognostic value of Cdk1 on overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models.ResultsAll samples displayed detectable Cdk1 expression with predominant location in the cytoplasm and nucleus. A high Cdk1 nuclear/cytoplasmic (N/C) expression ratio was correlated with poor overall survival (5-year survival rate: 26.3% vs 46.9%, N/C ratio ≥1.5 vs N/C ratio <1.5, log-rank p = 0.027). Accordingly, a Cdk1 N/C expression ratio ≥1.5 was identified as an independent risk factor by multivariate analysis (hazard ratio = 1.712, P = 0.039).ConclusionsWe suggest that Cdk1 N/C expression ratio determined by IHC staining could be an independent prognostic marker for colorectal cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-951) contains supplementary material, which is available to authorized users.

Perturbations in PI3K pathway and cyclin dependent kinase (CDK) pathway to predict complete responders in CRC patients treated with ADAPT therapy.

3610 Background: Aspirin or selective COX-2 inhibitor may improve overall survival (OS) in colorectal cancer (CRC) patients with PIK3CA mutations. However, routine use of anti-inflammatory agents i...

EEN regulates the proliferation and survival of multiple myeloma cells by potentiating IGF-1 secretion

The molecular mechanisms of multiple myeloma are not well defined. EEN is an endocytosis-regulating molecule. Here we report that EEN regulates the proliferation and survival of multiple myeloma cells, by regulating IGF-1 secretion. In the present study, we observed that EEN expression paralleled with cell proliferation, EEN accelerated cell proliferation, facilitated cell cycle transition from G1 to S phase by regulating cyclin-dependent kinases (CDKs) pathway, and delayed cell apoptosis via Bcl2/Bax-mitochondrial pathway. Mechanistically, we found that EEN was indispensable for insulin-like growth factor-1 (IGF-1) secretion and the activation of protein kinase B-mammalian target of rapamycin (Akt-mTOR) pathway. Exogenous IGF-1 overcame the phenotype of EEN depletion, while IGF-1 neutralization overcame that of EEN over-expression. Collectively, these data suggest that EEN may play a pivotal role in excessive cell proliferation and insufficient cell apoptosis of bone marrow plasma cells in multiple myeloma. Therefore, EEN may represent a potential diagnostic marker or therapeutic target for multiple myeloma.