Targeting USP7 to treat colorectal cancer

Using a panel of p53 CRISPR-knockout isogenic CRC models, we identified modest p53-dependent effects of AD04 on cell viability which correlated with increased p53 stabilisation and its transcriptional targets p21 and MDM2. Co-treatment with AD04 and 5FU induced a significant reduction in cell viability compared to treatment with AD04 or 5FU alone. Notably, this synergy was independent of p53 status.

We identified two independent mechanisms of synergy, in a p53 WT setting the synergy was dependent on caspase-8, but this was not the case in p53 mutant. We employed transcriptomic approaches to further characterise these effects. RNA-sequencing revealed TNFa signalling via NFΚB as a consistent pathway altered in response to both USP7 inhibition and its combination with 5FU.We further employed complex co-culture models to develop more clinically relevant models.

Again, we found that AD04 enhances the effects of 5FU, independent of p53. Moreover, co-cultures with activated T-cells further enhanced the effects of AD04/5FU in these co-cultures. Altogether, these results reveal a novel synergy between USP7 inhibition and 5FU that is not dependent on p53.<br><br><i>Thesis embargoed until 31 July 2030.</i>