TRIM24 as therapeutic target in endocrine treatment resistant breast cancer (ChIP-Seq)

While ERα+ breast cancer treatment is considered effective, resistance to endocrine therapy is common. Since ERα is still the main driver in most therapy-resistance tumors, alternative therapeutic strategies are needed to disrupt ERα transcriptional activity. In this work, we position TRIM24 as therapeutic target in endocrine resistance, in its role as key player of the ERα transcriptional complex. TRIM24 interacts with ERα and other well-known ERα-cofactors to facilitate ERα chromatin interactions, and allows for maintenance of active histone marks including H3K23ac and H3K27ac. Consequently, genetic perturbation of TRIM24 abrogates ERα-driven transcriptional programs and reduces tumor cell proliferation capacity. Using a recently-developed degrader targeting TRIM24, ERα-driven transcriptional output and growth was blocked, effectively treating not only endocrine-responsive cell lines, but also drug resistant derivates thereof as well as cell line models bearing activating ESR1 point mutations. Finally, using human tumor-derived organoid models, we could show efficacy of TRIM24 degrader in the endocrine responsive and resistant setting. Overall, our study positions TRIM24 as a central component for integrity and activity of the ERα transcriptional complex, with degradation-mediated perturbation of TRIM24 as promising therapeutic avenue in the treatment of primary and endocrine resistance breast cancer.