Transcriptomic change of ARDI1A mutant bladder cancer cell line treated with CPI-0209 or induced ARID1A expression

Advanced bladder cancer remains a difficult cancer to treat, and for the majority of patients, current standard treatments ultimately prove ineffective. These tumors frequently harbor mutations in the BAF complex subunit ARID1A, which has been reported to confer sensitivity to EZH2 inhibition in several tumor types. Here we describe the generation of CPI-0209, a best-in-class, orally available EZH2 inhibitor. We show that mutant bladder cancer lines harboring ARID1A loss of function (LOF) mutations are preferentially sensitive to inhibition of EZH2. Treatment with CPI-0209 not only elicits a significant monotherapeutic response in ARID1A mutant models, it also outperforms cisplatin and improves response in chemo-resistant models. These findings shine light on new therapeutic opportunities for patients with advanced urothelial carcinoma. HT1376-TetON control cells and a clonal HT1376-TetON-ARID1A cell line were induced with 50 ng/ml doxycycline for 24 hours and then treated for 4 days with DMSO or 250 nM CPI-0209.