Introduction

We have previously shown that HPV E7 sensitizes cells to the inhibition of Aurora A/B kinases (AKi) and treatment is effective at eliminating early tumours and reducing late tumours [1, 2]. Functionally, AKi’s cause HPV cells to take 5X longer to traverse mitosis and key anti-apoptotic proteins degrade and apoptosis is induced. Here we wish to enhance the effect of AKi’s by adding inhibitors of Bcl-2, Bcl-XL and Mcl1. We also wish to test the combination of radiation therapy (RT) with AKi in cervical PDX models. ls.

Methods

Drugs were added to HeLa /Caski cells and cell viability via MTT and cell imaging undertaken. Dose-response curves and isobolograms for synergy were generated. A PDX expressing HPV16E7 was implanted orthotopically in the cervix and treated with RT (30Gy;2Gy/day), with or without Alisertib (30mg/kg/day) given concurrently with RT daily (3wks). Expression of anti-apoptotic and DNA damage response proteins were evaluated by western blot and IHC respectively.

Results

The combination of Alisertib and Venetoclax was more effective than either drug alone. Enhanced apoptosis was observed with increased PARP cleavage. A1210477 and A1331852 were similar. In the PDX model, RT plus Alisertib showed tumour growth delay compared with RT alone. Reduced lymph node metastasis was observed with Alisertib alone. Combination treatment resulted in the loss of RT-induced anti-apoptotic expression andenhanced γ-H2AX phosphorylation. Loss of Aurora activity reduced the ability of cells to manage DNA damage induced by RT.

Conclusions

Combination of AKi’s with Bcl-2 family inhibitors was highly effective at killing HPV cells, likely by accelerating apoptosis during mitotic delay. Alisertib may enhance RT response in patients and appears to reduce metastasis on its own. These studies present a promising approach to treating aggressive HPV cancers and may apply to other HPV-related cancers.

1. Martin D et al. MCT 2017;16:1934-41.

2. Gabrielli B, et al. MCT 2015;14:2753-61