ABSTRACT
PURPOSE: Neuroblastoma is a pediatric cancer that continues to exact significant morbidity and mortality. Recently, a number of cell-cycle proteins, particularly those within the Cyclin D/CDK4/CDK6/RB network, have been shown to exert oncogenic roles in neuroblastoma, suggesting that their therapeutic exploitation might improve patient outcomes. EXPERIMENTAL PROCEDURES: We evaluated the effect of dual CDK4/CDK6 inhibition on neuroblastoma viability using LEE011 (Novartis Oncology), a highly specific CDK4/6 inhibitor. RESULTS: Treatment with LEE011 significantly reduced proliferation in 12 of 17 human neuroblastoma-derived cell lines by inducing cytostasis at nanomolar concentrations (mean IC50 = 307 ± 68 nmol/L in sensitive lines). LEE011 caused cell-cycle arrest and cellular senescence that was attributed to dose-dependent decreases in phosphorylated RB and FOXM1, respectively. In addition, responsiveness of neuroblastoma xenografts to LEE011 translated to the in vivo setting in that there was a direct correlation of in vitro IC50 values with degree of subcutaneous xenograft growth delay. Although our data indicate that neuroblastomas sensitive to LEE011 were more likely to contain genomic amplification of MYCN (P = 0.01), the identification of additional clinically accessible biomarkers is of high importance. CONCLUSIONS: Taken together, our data show that LEE011 is active in a large subset of neuroblastoma cell line and xenograft models, and supports the clinical development of this CDK4/6 inhibitor as a therapy for patients with this disease. Clin Cancer Res; 19(22); 6173-82. ©2013 AACR.
Subject(s)
Aminopyridines/pharmacology , Cyclin-Dependent Kinase 4/antagonists & inhibitors , Cyclin-Dependent Kinase 6/antagonists & inhibitors , Neuroblastoma/drug therapy , Protein Kinase Inhibitors/therapeutic use , Purines/pharmacology , Animals , Apoptosis/drug effects , Cell Cycle Checkpoints/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Cellular Senescence/drug effects , Child , Cyclin-Dependent Kinase 4/genetics , Cyclin-Dependent Kinase 6/genetics , Forkhead Box Protein M1 , Forkhead Transcription Factors/metabolism , Humans , Mice , Mice, SCID , N-Myc Proto-Oncogene Protein , Neoplasm Transplantation , Neuroblastoma/genetics , Nuclear Proteins/genetics , Oncogene Proteins/genetics , Phosphorylation/drug effects , Polymorphism, Single Nucleotide , RNA Interference , RNA, Small Interfering , Retinoblastoma Protein/metabolism , Signal Transduction/drug effects , Transplantation, HeterologousABSTRACT
Activating mutations in the anaplastic lymphoma kinase (ALK) gene were recently discovered in neuroblastoma, a cancer of the developing autonomic nervous system that is the most commonly diagnosed malignancy in the first year of life. The most frequent ALK mutations in neuroblastoma cause amino acid substitutions (F1174L and R1275Q) in the intracellular tyrosine kinase domain of the intact ALK receptor. Identification of ALK as an oncogenic driver in neuroblastoma suggests that crizotinib (PF-02341066), a dual-specific inhibitor of the ALK and Met tyrosine kinases, will be useful in treating this malignancy. Here, we assessed the ability of crizotinib to inhibit proliferation of neuroblastoma cell lines and xenografts expressing mutated or wild-type ALK. Crizotinib inhibited proliferation of cell lines expressing either R1275Q-mutated ALK or amplified wild-type ALK. In contrast, cell lines harboring F1174L-mutated ALK were relatively resistant to crizotinib. Biochemical analyses revealed that this reduced susceptibility of F1174L-mutated ALK to crizotinib inhibition resulted from an increased adenosine triphosphate-binding affinity (as also seen in acquired resistance to epidermal growth factor receptor inhibitors). Thus, this effect should be surmountable with higher doses of crizotinib and/or with higher-affinity inhibitors.
