Abstract INTRODUCTION AND OBJECTIVE: We previously discovered a first-in-class human Chondroitinase (Chase) that degrades chondroitin sulfate. This Chase is a splice variant of HYAL4 (V1) and promotes a malignant phenotype and chemoresistance in bladder cancer (BC) cells. We evaluated the diagnostic and prognostic potential of V1-Chase and its functions in driving treatment resistant BC in preclinical models. METHODS: Efficacy of the V1 (qPCR) and Chase (ELISA-like assay) was evaluated in three test and validation cohorts (total n = 925; BC=239; non-BC = 686). 40 cystectomy specimens from MIBC patients who received adjuvant Gemcitabine plus cisplatin (G+C) treatment. V1 was expressed in BC cell lines or silenced and the transfectants were analyzed for sensitivity to Gemcitabine (Gem) and Cisplatin. The mechanism of Gem resistance was evaluated in preclinical in vitro and in vivo models. RESULTS: Chase levels were 7-10-fold elevated in patients with BC compared to patients with benign genitourinary conditions, history of BC, or other cancers. In all three cohorts, Chase test detected BC with 92% sensitivity and 85% specificity. Chase test correctly diagnosed atypical cytology inferences. V1 induced an invasive stem cell phenotype. V1’s Chase activity induced Gem resistance in BC cells by cleaving CD44 and promoting intracellular JAK2/Stat3 signaling which caused up-regulation of cytidine deaminase (CDA). CDA induces Gem metabolism and efflux of dFdU, an inactive Gem metabolite. In patients with MIBC, V1/p-JAK2/CDA signature predicted failure to G+C adjuvant/salvage treatment (P0.0001). STAT3 and CDA inhibitors re-sensitized V1-expressing cells to Gem. Transcriptome and gene enrichment analyses showed V1 induces JAK-Stat3, inflammatory and invasion/metastasis gene signatures, which were validated in clinical specimens. V1-expressing tumors were Gem resistant but were re-sensitized to Gem treatment in combination with a CDA inhibitor. CONCLUSION: V1/Chase is a potential diagnostic and prognostic biomarker for bladder cancer and drives muscle-invasion, metastasis, and Gem resistance in BC. Inhibitors of the Chase signaling pathway overcome V1-induced Gem resistance, suggesting a precision-based treatment approach to improve treatment response. Support: 1R01CA283699-03 Citation Format: Dhasarathan Ganesan, Karina Aguilar, Tianyu yang, Bal L. Lokeshwar, Vinata B. Lokeshwar. Biomarker-guided treatment approach For advanced bladder cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7713.
Ganesan et al. (Fri,) studied this question.