Abstract 4407: Next generation CDK2/9 inhibitor CYC065 triggers anaphase catastrophe in diverse aneuploid cancers and markedly inhibits growth and metastasis
Authors: Kawakami Masanori , Mustachio Lisa Maria , Chen Yulong , Chen Zibo , Roszik Jason , Liu Xi , Dmitrovsky Ethan 
Published: August 2019

Genetically-unstable cancer cells have supernumerary centrosomes and aneuploidy (a hallmark of cancer). CDK2 antagonism inhibits clustering of excessive centrosomes at mitosis leading to multipolar cell division and apoptotic death. This process is called anaphase catastrophe. Anaphase catastrophe affects preferentially aneuploid cancer cells while sparing normal cells with two centrosomes. CYC065 (Cyclacel) is a next-generation CDK2/9 inhibitor that is undergoing clinical trials. Here, we explored CYC065 activity against aneuploid lung and other cancers. CYC065 substantially inhibited growth, triggered apoptosis, and induced anaphase catastrophe in murine (ED1, LKR13, and 393P) and human (Hop62, A549, and H1299) lung cancer cells. In marked contrast, these effects were largely unseen in bipolar immortalized pulmonary epithelial (murine C10 and human BEAS-2B) cells. Notably, anaphase catastrophe was induced by CYC065-treatment even in pancreatic and colon cancers that are often driven by the KRAS oncoprotein. This suggests that engaging anaphase catastrophe is a general antineoplastic mechanism. Comprehensive expression analysis of nearly 300 growth-regulatory proteins was performed after CYC065 treatment in lung cancer cells using Reverse Phase Protein Arrays (RPPAs). In addition to known CDK targets (such as phosphorylated retinoblastoma protein), FAK phosphorylation and SAC phosphorylation that are known to regulate metastasis were unexpectedly down-regulated. Consistent with this finding, in vitro migration and invasion CYC065 treatment assays markedly inhibited migration and invasion of lung cancer cells. CYC065 anti-neoplastic effects were interrogated in mice. CYC065 significantly inhibited tumor growth in several lung cancer syngeneic xenografts and patient-derived xenografts (PDXs) and reduced metastasis of 344SQ lung cancer cells in a syngeneic tail-vein injection model. Immunohistochemistry (IHC) studies of resected PDX tumors revealed downregulation of p-CDK2 (Thr160) and MCL1 expression after CYC065 treatment which is consistent with CDK2/9 antagonism, respectively. In summary, CYC065 engages anaphase catastrophe and elicits marked antineoplastic effects in diverse cancers. These effects are due to mechanisms that confer after CDK2/9 inhibition, anaphase catastrophe, MCL1 down-regulation and suppression of proteins that regulate metastasis. Taken together, findings reveal that anaphase catastrophe is a general antineoplastic mechanism engaged in aneuploid cancers. Intriguingly, this mechanism is activated after CDK2/9 inhibition of lung and other cancers, including those driven by the KRAS oncoprotein.

Citation Format: Masanori Kawakami, Lisa Maria Mustachio, Yulong Chen, Zibo Chen, Jason Roszik, Xi Liu, Ethan Dmitrovsky. Next generation CDK2/9 inhibitor CYC065 triggers anaphase catastrophe in diverse aneuploid cancers and markedly inhibits growth and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4407.