ribociclib and Neoplasms--Germ-Cell-and-Embryonal

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.

Topics: Aminopyridines; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Cell Cycle; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase 6; Female; Humans; Liposarcoma; Lymphoma, Mantle-Cell; Melanoma; Neoplasms, Germ Cell and Embryonal; Piperazines; Protein Kinase Inhibitors; Purines; Pyridines; Signal Transduction

Germ cell tumours (GCTs) are the most common solid malignancies in young men. Although high cure rates can be achieved, metastases, resistance to cisplatin-based therapy and late toxicities still represent a lethal threat, arguing for the need of new therapeutic options. In this study, we analysed the potential of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors palbociclib and ribociclib (PaRi) as molecular drugs to treat cisplatin-resistant and -sensitive paediatric and adult GCTs.. Ten GCT cell lines, including cisplatin-resistant subclones and non-malignant controls, were treated with PaRi and screened for changes in viability (triphenyl tetrazolium chloride (XTT) assay), apoptosis rates (flow cytometry, caspase assay), the cell cycle (flow cytometry), the transcriptome (RNA-sequencing, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and on protein level (western blot). Expression profiling was performed on paediatric and adult GCT tissues (expression microarrays, qRT-PCR, immunohistochemistry, 'The Cancer Genome Atlas' database).. We demonstrate that adult GCTs highly express CDK4, while paediatric GCTs strongly express CDK6 instead. Thus, both GCT types are potentially treatable by PaRi. GCTs presented as highly sensitive towards PaRi, which caused a decrease in viability, cell cycle arrest and apoptosis. Although GCTs mainly arrested in the G1/G0 phase, some embryonal carcinoma cell lines were able to bypass the G1/S checkpoint and progressed to the G2/M phase. We found that upregulation of CDK3 and downregulation of many mitosis regulation factors, like the HAUS genes, might be responsible for bypassing the G1/S checkpoint and termination of mitosis, respectively. We postulate that GCT cells do not tolerate these alterations in the cell cycle and eventually induce apoptosis.. Our study highlights PaRi as therapeutic options for cisplatin-resistant and -sensitive paediatric and adult GCTs.

Topics: Adult; Aminopyridines; Cell Line, Tumor; Cell Proliferation; Cell Survival; Child; Cisplatin; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase 6; Drug Resistance, Neoplasm; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Male; Neoplasms, Germ Cell and Embryonal; Piperazines; Purines; Pyridines; Sequence Analysis, RNA; Up-Regulation