Ferroptosis suppression and its association with chemoradiotherapy resistance in muscle-invasive bladder cancer.

Abstract

839 Background: Chemoradiotherapy (CRT) within trimodality therapy (TMT) offers a curative-intent, bladder-preserving option for patients with muscle-invasive bladder cancer (MIBC), yet its long-term efficacy is limited by treatment resistance. While alterations in DNA damage response genes have been proposed as candidate radiosensitivity biomarkers, the broader molecular landscape influencing CRT outcomes remains unclear. Methods: We conducted comprehensive transcriptomic profiling of pre-treatment tumors from 179 patients undergoing TMT, representing the largest and most uniform bladder-preservation cohort analyzed to date, to delineate molecular determinants of CRT response. To complement the clinical analysis, CRT-resistant bladder cancer cell models were used to perform integrative RNA sequencing, lipidomic profiling, and genome-wide CRISPR/Cas9 loss-of-function screening. Results: Patients with disease progression showed significantly poorer survival than progression-free cases, accompanied by distinct immune- and lipid metabolism–related transcriptional programs. Integrating these findings, we derived a ferroptosis suppressor signature (FSS). High FSS expression correlated with poor CRT response, immune-excluded microenvironments, and inferior survival, and was enriched in Basal/Squamous subtypes, whereas FSS-low tumors were predominantly Luminal Unstable and immune-inflamed. Resistant cells mirrored these transcriptomic and metabolic traits and exhibited restored radiosensitivity upon ferroptosis induction. A CRISPR/Cas9 screen further identified key ferroptosis suppressor genes—including GPX4 , SLC7A11 , and NFE2L2 —as radiosensitizing vulnerabilities. Conclusions: This integrative clinical and functional analysis highlights ferroptosis suppression as a central molecular determinant of CRT resistance in bladder preservation therapy. Incorporating ferroptosis suppressor status alongside molecular subtype and immune contexture may enhance patient stratification and support personalized treatment decision-making in bladder-preserving approaches. Multivariable Cox regression for rPFS and OS. Variable HR (95% CI) for rPFS HR (95% CI) for OS FSS-high 2.73 (1.76–4.25) *** 2.83 (1.71–4.71) *** LVI (+) 1.76 (1.06–3.01) * 2.36 (1.25–4.45) ** Ba/Sq 1.88 (1.17–3.01) ** 1.21 (0.72–2.01) cT ≥T3 1.28 (0.82–2.00) 　 1.23 (0.74–2.03) Invasive (+) 1.68 (0.40–7.03) 　 0.95 (0.24–3.72) Grade (+) 1.62 (0.59–4.47) 　 1.08 (0.35–3.34) Age ≥75 0.59 (0.34–1.02) 　 0.73 (0.40–1.33) Concomitant CIS (+) 0.64 (0.34–1.20) 　 0.43 (0.18–1.02) 　 HR, hazard ratio; CI, confidence interval; rPFS, radiographic progression-free survival; OS, overall survival; FSS, ferroptosis suppresive signature; LVI, lynphvascular invasion; Ba/Sq, basal/squamous subtype; CIS, carcinoma in situ; *** P < 0.001; ** P < 0.01, * P < 0.05.