dinaciclib and Triple-Negative-Breast-Neoplasms

Low molecular weight cyclin E (LMW-E) isoforms, overexpressed in a majority (~70 %) of triple-negative breast cancers (TNBC), were found in preclinical models to mediate tumorigenesis through binding and activation of CDK2. CDK1/CDK2 inhibitors, such as dinaciclib, combined with anthracyclines, were synergistic in decreasing viability of TNBC cell lines. Based on this data, a phase 1 study was conducted to determine the maximum tolerated dose of dinaciclib in combination with epirubicin in patients with metastatic TNBC.. Cohorts of at least 2 patients were treated with escalating doses of dinaciclib given on day 1 followed by standard dose of epirubicin given on day 2 of a 21 day cycle. No intra-patient dose escalation was allowed. An adaptive accrual design based upon toxicity during cycle 1 determined entry into therapy cohorts. The target acceptable dose limiting toxicity (DLT) to advance to the next treatment level was 30 %.. Between 9/18/2012 and 7/18/2013, 9 patients were enrolled and treated at MD Anderson Cancer Center. DLTs included febrile neutropenia (grade 3, n = 2), syncope (grade 3, n = 2) and vomiting (grade 3, n = 1). Dose escalation did not proceed past the second cohort due to toxicity. After further accrual, the first dose level was also found to be too toxic. No treatment responses were noted, median time to progression was 5.5 weeks (range 3-12 weeks). Thus, accrual was stopped rather than explore the -1 dose level.. The combination of dinaciclib and epirubicin is associated with substantial toxicities and does not appear to be an effective treatment option for TNBC.

Topics: Adult; Aged; Antibiotics, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Bridged Bicyclo Compounds, Heterocyclic; Cyclic N-Oxides; Cyclin-Dependent Kinases; Epirubicin; Female; Humans; Indolizines; Maximum Tolerated Dose; Middle Aged; Protein Kinase Inhibitors; Pyridinium Compounds; Treatment Outcome; Triple Negative Breast Neoplasms

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with low survival rate and a lack of biomarkers and targeted treatments. Here, we target pyruvate kinase M2 (PKM2), a key metabolic component of oncogenesis. In patients with TNBC, PKM2pS37 was identified as a prominent phosphoprotein corresponding to the aggressive breast cancer phenotype that showed a characteristic nuclear staining pattern and prognostic value. Phosphorylation of PKM2 at S37 was connected with a cyclin-dependent kinase (CDK) pathway in TNBC cells. In parallel, pyruvate kinase activator TEPP-46 bound PKM2pS37 and reduced its nuclear localization. In a TNBC mouse xenograft model, treatment with either TEPP-46 or the potent CDK inhibitor dinaciclib reduced tumor growth and diminished PKM2pS37. Combinations of dinaciclib with TEPP-46 reduced cell invasion, impaired redox balance, and triggered cancer cell death. Collectively, these data support an approach to identify PKM2pS37-positive TNBC and target the PKM2 regulatory axis as a potential treatment. SIGNIFICANCE: PKM2 phosphorylation marks aggressive breast cancer cell phenotypes and targeting PKM2pS37 could be an effective therapeutic approach for treating triple-negative breast cancer.

Topics: Active Transport, Cell Nucleus; Animals; Biomarkers, Tumor; Carrier Proteins; Cell Line, Tumor; Collagen; Cyclic N-Oxides; Drug Combinations; Genome, Human; Humans; Indolizines; Laminin; MCF-7 Cells; Membrane Proteins; Mice; Neoplasm Invasiveness; Neoplasm Transplantation; Neoplasms; Oxidation-Reduction; Phenotype; Phosphorylation; Protein Isoforms; Proteoglycans; Proteomics; Pyridazines; Pyridinium Compounds; Pyrroles; Pyruvate Kinase; Thyroid Hormone-Binding Proteins; Thyroid Hormones; Triple Negative Breast Neoplasms

Topics: Animals; Benzamides; Biphenyl Compounds; Bridged Bicyclo Compounds, Heterocyclic; Cyclic N-Oxides; Cyclin-Dependent Kinase 2; Enhancer of Zeste Homolog 2 Protein; Estrogen Receptor alpha; Female; Humans; Indolizines; Mammary Glands, Human; Mammary Neoplasms, Experimental; Mice; Mice, Transgenic; Morpholines; Phosphorylation; Pyridinium Compounds; Pyridones; Receptor, ErbB-2; Receptors, Progesterone; Triple Negative Breast Neoplasms

PARP inhibitors (PARPi) benefit only a fraction of breast cancer patients. Several of those patients exhibit intrinsic/acquired resistance mechanisms that limit efficacy of PARPi monotherapy. Here we show how the efficacy of PARPi in triple-negative breast cancers (TNBC) can be expanded by targeting MYC-induced oncogenic addiction. In BRCA-mutant/sporadic TNBC patients, amplification of the MYC gene is correlated with increased expression of the homologous DNA recombination enzyme RAD51 and tumors overexpressing both genes are associated with worse overall survival. Combining MYC blockade with PARPi yielded synthetic lethality in MYC-driven TNBC cells. Using the cyclin-dependent kinase inhibitor dinaciclib, which downregulates MYC expression, we found that combination with the PARPi niraparib increased DNA damage and downregulated homologous recombination, leading to subsequent downregulation of the epithelial-mesenchymal transition and cancer stem-like cell phenotypes. Notably, dinaciclib resensitized TBNC cells, which had acquired resistance to niraparib. We found that the synthetic lethal strategy employing dinaciclib and niraparib was also highly efficacious in ovarian, prostate, pancreatic, colon, and lung cancer cells. Taken together, our results show how blunting MYC oncogene addiction can leverage cancer cell sensitivity to PARPi, facilitating the clinical use of c-myc as a predictive biomarker for this treatment.

Topics: Animals; Apoptosis; BRCA1 Protein; BRCA2 Protein; Bridged Bicyclo Compounds, Heterocyclic; Cell Proliferation; Cyclic N-Oxides; DNA Damage; DNA Repair; Drug Resistance, Neoplasm; Drug Therapy, Combination; Female; Humans; Indolizines; Mice; Mice, Nude; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Proto-Oncogene Proteins c-myc; Pyridinium Compounds; Synthetic Lethal Mutations; Triple Negative Breast Neoplasms; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Poor prognosis in triple-negative breast cancer (TNBC) is due to an aggressive phenotype and lack of biomarker-driven targeted therapies. Overexpression of cyclin E and phosphorylated-CDK2 are correlated with poor survival in patients with TNBC, and the absence of CDK2 desensitizes cells to inhibition of Wee1 kinase, a key cell-cycle regulator. We hypothesize that cyclin E expression can predict response to therapies, which include the Wee1 kinase inhibitor, AZD1775.. Mono- and combination therapies with AZD1775 were evaluated in TNBC cell lines and multiple patient-derived xenograft (PDX) models with different cyclin E expression profiles. The mechanism(s) of cyclin E-mediated replicative stress were investigated following cyclin E induction or CRISPR/Cas9 knockout by a number of assays in multiple cell lines.. Cyclin E overexpression (i) is enriched in TNBCs with high recurrence rates, (ii) sensitizes TNBC cell lines and PDX models to AZD1775, (iii) leads to CDK2-dependent activation of DNA replication stress pathways, and (iv) increases Wee1 kinase activity. Moreover, treatment of cells with either CDK2 inhibitors or carboplatin leads to transient transcriptional induction of cyclin E (in cyclin E-low tumors) and result in DNA replicative stress. Such drug-mediated cyclin E induction in TNBC cells and PDX models sensitizes them to AZD1775 in a sequential treatment combination strategy.

Topics: Animals; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Cell Cycle Proteins; Cell Line, Tumor; Cyclic N-Oxides; Cyclin E; Disease Models, Animal; DNA Repair; DNA Replication; Drug Resistance, Neoplasm; Gene Expression; Humans; Indolizines; Mice; Mice, Knockout; Models, Biological; Nuclear Proteins; Prognosis; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyridinium Compounds; Pyrimidinones; Stress, Physiological; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays

Cyclin-dependent kinases (CDKs) are potential cancer therapeutic targets because of their critical role in promoting cell growth. Dinaciclib is a novel CDK inhibitor currently under clinical evaluation for the treatment of advanced malignancies. In this study, we demonstrated the anti-tumor activity of dinaciclib in triple negative breast cancer (TNBC) patient derived xenograft (PDX) and cell lines in vitro and in vivo. Treatment with dinaciclib induced cell cycle arrest at G2/M phase and marked apoptosis. These changes were accompanied by reduced phosphorylation of CDK1 and retinoblastoma (Rb) protein and decreased protein levels of cyclin B1, cMYC and survivin. We further demonstrated that siRNA knockdown of CDK9, the kinase subunit of positive transcription elongation factor b (P-TEFb), instead of CDK1 or CDK2, reduced the levels of cyclin B1 and MYC in TNBC cell lines. These data support the importance of CDK9, in addition to CDK1, in mediating the growth inhibitory effect of dinaciclib in TNBC. Further investigation of CDK9 as a therapeutic target in TNBC is needed.

Topics: Animals; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cyclic N-Oxides; Cyclin B1; Cyclin-Dependent Kinase 9; Cyclin-Dependent Kinases; Female; Gene Expression Regulation, Neoplastic; Humans; Indolizines; Inhibitor of Apoptosis Proteins; Mice, Inbred NOD; Mice, SCID; Phosphorylation; Proto-Oncogene Proteins c-myc; Pyridinium Compounds; Survivin; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays

Although poly(ADP-ribose) polymerase (PARP) inhibitors are active in homologous recombination (HR)-deficient cancers, their utility is limited by acquired resistance after restoration of HR. Here, we report that dinaciclib, an inhibitor of cyclin-dependent kinases (CDKs) 1, 2, 5, and 9, additionally has potent activity against CDK12, a transcriptional regulator of HR. In BRCA-mutated triple-negative breast cancer (TNBC) cells and patient-derived xenografts (PDXs), dinaciclib ablates restored HR and reverses PARP inhibitor resistance. Additionally, we show that de novo resistance to PARP inhibition in BRCA1-mutated cell lines and a PDX derived from a PARP-inhibitor-naive BRCA1 carrier is mediated by residual HR and is reversed by CDK12 inhibition. Finally, dinaciclib augments the degree of response in a PARP-inhibitor-sensitive model, converting tumor growth inhibition to durable regression. These results highlight the significance of HR disruption as a therapeutic strategy and support the broad use of combined CDK12 and PARP inhibition in TNBC.

Topics: Amino Acid Sequence; Animals; BRCA1 Protein; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Cyclic N-Oxides; Cyclin-Dependent Kinases; DNA Damage; DNA Repair; Drug Resistance, Neoplasm; Female; Gene Expression Regulation, Neoplastic; Gene Knockout Techniques; Homologous Recombination; Humans; Indolizines; Mice; Mutation; Poly(ADP-ribose) Polymerase Inhibitors; Protein Kinase Inhibitors; Pyridinium Compounds; RNA, Small Interfering; Transcription, Genetic; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays