90P - Discovery of CMPD1 as a tumor-specific cytotoxic microtubule inhibitor

Background

Microtubule-targeting agents (MTAs) have been widely used as first- and second-line agents in various cancers for several decades. Furthermore, the value of MTAs is currently increasing due to their usefulness as combination drugs with immune checkpoint inhibitors. However, many development resources have been devoted to molecular-targeted agents, and the development of new MTAs has not progressed, leaving many patients struggling with the toxicity of existing MTAs. In other words, there is an urgent need to develop new microtubule inhibitors with high cancer-specificity.

Methods

Time-lapse images were taken every 2-3 minutes for 24-72 hours. Microtubules nucleated from GMPCPP-stabilized seeds were prepared and imaged using total internal reflection fluorescence (TIRF) microscopy (Ecklund KH et al. Nature Comm 2017 ). Tubulin polymerization activity, Trans-well migration assay were measured using the HTS-Tubulin Polymerization Assay Biochem Kit (Denver, CO, USA), CytoSelect 24-well cell invasion assay kits (Cell Biolabs). Orthotopic breast cancer model (MDA MB 231) and treatment - CMPD1 (i.p., 15 μg/mouse/inj, 10 times for 3 wks), Taxol (i.p., 5 mg/kg/inj, 10 times for 3 wks) were performed. Vascular invasion was identified by tumor cells within vessels in HE staining. RNAs Sequencing libraries were prepared with the TruSeq stranded mRNA kit and sequenced on NovaSeq6000 at Macrogen Japan.

Results

CMPD1, a known inhibitor of MAP kinase-activated protein kinase 2(MK2), rapidly induces microtubule depolymerization in several cancer cell-lines, resulting in robust prometaphase arrest. CMPD1 levels alter the fate of cancer cells, either inducing mitotic slippage or resulting in mitotic defects. CMPD1 inhibits microtubule polymerization and specifically induces microtubule depolymerization at the plus end in in vitro assays; resulting in significant inhibition of tumor growth, cancer cell migration, and invasion in both in vitro and in vivo. Furthermore, clinically relevant low doses of CMPD1 induced severe and prolonged mitotic failure specifically in cancer cells, but not in non-transformed cells, with only modest effects on microtubules in vitro.

Conclusions

CMPD1 has the potential to serve as a cancer cell-selective MTA chemotherapeutic agent.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

JSPS KAKENHI 21K08638.

Disclosure

All authors have declared no conflicts of interest.