Combining the albumin-bilirubin (ALBI) score and ECOG performance status for enhanced prognostication in advanced biliary tract cancer treated with durvalumab-based immunochemotherapy.

485 Background: The Eastern Cooperative Oncology Group performance status (ECOG PS) is fundamental for prognostication in advanced biliary tract cancer (BTC). The albumin-bilirubin (ALBI) score objectively reflects hepatic reserve; however, its value in combination with ECOG PS for patients treated with durvalumab plus gemcitabine-cisplatin (GCD) remains unclear. Methods: We analyzed consecutive patients with advanced BTC treated with first-line GCD at three Taiwanese institutions between August 2021 and March 2025. Patients were stratified into cohort-specific ALBI tertiles (Q1–Q3). Survival outcomes were estimated using Kaplan–Meier and Cox regression analyses. Tumor response and adverse events were assessed using RECIST v1.1 and CTCAE v5.0, respectively. Predictive accuracy for 6- and 12-month overall survival (OS) was compared among ECOG PS, ALBI, and their combination using time-dependent area under the receiver operating characteristic curves (AUC) and the Akaike information criterion (AIC). Results: Among 172 patients, the median OS was 13.8 months and progression-free survival (PFS) was 5.1 months. OS decreased progressively from ALBI Q1 to Q3 (24.0, 14.4, and 5.9 months; p < 0.001). In multivariate analysis, ALBI Q3 (vs. Q1) remained independently associated with poorer OS (adjusted hazard ratio HR 2.16, p = 0.016). ALBI correlated with ECOG PS (p = 0.004), but each maintained independent prognostic value. Combined ALBI + ECOG yielded higher AUCs (0.750 at 6 months; 0.683 at 12 months) and lower AICs than either model alone. The median OS ranged from 24.0 months in patients with ECOG 0–1 and ALBI Q1 to 2.4 months in those with ECOG 2–3 and ALBI Q3. Higher ALBI scores predicted lower response rates and increased toxicities ≥ grade 3. Conclusions: Baseline ALBI score independently predicted survival, tumor response, and toxicity risk in patients with advanced BTC treated with GCD. Combining ALBI with ECOG PS improves prognostic discrimination and may guide treatment and stratification in advanced BTC.