Determinants in trimodality therapy for bladder cancer: Overcoming chemoradiotherapy resistance via ferroptosis.

Abstract

4599 Background: Expanding bladder preservation therapy can improve quality of life in patients with bladder cancer. This study aims to identify genetic determinants associated with trimodality therapy (TMT) for bladder preservation in bladder cancer (BC) patients and develop novel strategies to overcome chemoradiotherapy (CRT) resistance. Methods: Multi-omics analysis integrating RNA sequencing and whole exome sequencing (WES) was performed on clinical BC samples from 200 patients who underwent TMT in the OMPU-NCC dataset. The genomic profile of CRT-resistant BC cell lines was also analyzed. Ferroptosis signature scores were calculated using genes curated from the FerrDbV2 database. Results: WES revealed frequent alterations in DNA damage response (DDR) genes (Fig. 1A). Kaplan-Meier analysis showed significantly improved progression-free survival (PFS; HR 0.5840, 95% CI 0.3891-0.8765, P = 0.0157) and overall survival (OS; HR 0.5384, 95% CI 0.3331-0.8700, P = 0.0296) in patients with DDR alterations (Fig. 1B). Transcriptomic analysis identified distinct expression profiles between responders and progressors post-TMT. Gene Ontology analysis showed downregulation of immune response and lipid metabolism pathways in progressors (Fig. 2A). Analysis of the ferroptosis signature, which links these pathways, indicated that a high ferroptosis-suppressor signature score was correlated with worse survival outcomes (PFS: HR 2.713, 95% CI 1.818-4.047, P < 0.0001; OS: HR 2.311, 95% CI 1.502-3.557, P = 0.0001), in contrast to the driver signature (Fig. 2B). RNA-sequencing of cell lines revealed significant differences in ferroptosis signature between parental and CRT-resistant strains (Fig. 2C). The combination of the ferroptosis inducer and irradiation overcame resistance in the T24R cell line, which is enriched with ferroptosis-suppressor genes. Conclusions: Key survival determinants post-CRT were highlighted, positioning ferroptosis as a target for overcoming resistance (Fig. 2D). Combining ferroptosis inducers with irradiation could offer a new therapeutic avenue for expanding bladder preservation. Survival outcome after TMT according to DDR alteration and ferroptosis signature score. Status Number of patients PFS after TMT (median, months) HR (95% CI) OS after TMT (median, months) HR (95% CI) DDR intact 49 25 ref 48 ref DDR alteration 151 61 0.584 (0.389 to 0.877) NR 0.538 (0.333 to 0.870) Ferroptosis signature low 102 NR ref NR ref Ferroptosis signature high 98 16 2.713 (1.818 to 4.047) 27 2.311 (1.502 to 3.557) PFS = progression free survival, TMT = trimodality therapy, HR = hazard ratio, CI = confidence interval, OS = overall survival, DDR = DNA damage response, NR = not reached.