Investigating KIF20A as a therapeutic target in glioblastoma

Project Summary/Abstract Elevated expression of KIF20A, a mitotic kinesin required to promote cytokinesis, the final step of cell division, is a near-universal feature of human cancer. Increased KIF20A levels are associated with poor prognosis in multiple tumor types and correlate with chromosomal instability (CIN). Cancer cells are sensitive to loss of

KIF20A function via both small molecule (KIF20Ai) and CRISPR-mediated KIF20A knockout (KIF20A-KO) whereas RNAi-mediated depletion of KIF20A is generally tolerated and has not informed us of the enzyme’s role in CIN. We find that increasing KIF20Ai concentrations leads to a dose-dependent loss of viability that correlates

with an increase in mitotic duration caused by defective chromosome congression. While perturbing mitosis is a clinically relevant therapeutic strategy, current agents target microtubules and induce neurotoxicity, which limits the utility of these agents and precludes their use in tumors of the central nervous system. Glioblastoma (GBM;

isocitrate dehydrogenase [IDH]-wild-type) is an aggressive, highly proliferative brain tumor with limited treatment options. Radiotherapy is central to standard of care treatment for GBM. However, refractory cells ultimately lead to recurrence and highlight the need for new strategies. We and others have shown that perturbing mitosis is a

vulnerability of GBM cells and have demonstrated overexpression of KIF20A in these tumors. Indeed, we find that patient-derived models of GBM are sensitive to KIF20Ai. In contrast, non-transformed cells have low sensitivity to KIF20Ai. In addition, as mitotic cells are highly sensitive to radiotherapy, the mitotic arrest induced

by KIF20Ai offers the potential for radiosensitizing these tumors, enhancing the current standard of care. Based on these observations and our preliminary data, we hypothesize that cancer cells utilize a previously underappreciated activity of KIF20A to promote efficient mitotic progression and prevent CIN. Furthermore, we

postulate that blocking this function has therapeutic potential. The objective of this proposal is to further characterize the importance of KIF20A activity in early mitosis and investigate the impact of KIF20Ai as a potential new therapeutic strategy for GBM. Two Aims are proposed; 1) Define the requirement for KIF20A in

early mitosis by establishing the impact of KIF20A-KO on early mitosis, identifying the essential KIF20A function, and examining factors that dictate KIF20Ai sensitivity, 2) Determine the impact of KIF20Ai on tumor growth by comparing KIF20Ai to radiation and testing KIF20Ai as a radiosensitizer in orthotopic GBM PDX models. The

successful completion of this work will provide rationale to further explore 1) the cell biology of KIF20A and KIF20Ai, to further our understanding of CIN, and identify cellular characteristics and mechanisms that dictate sensitivity to KIF20Ai, and 2) the preclinical impact and translational potential of KIF20Ai as a non-microtubule-

targeting anti-mitotic strategy, both as a single agent and combination strategy in GBM and other tumor types.