Conference Abstracts - The 8th International Cancer Congress
Vol. 6, Issue Supplement 2, 2026 · S1-2
Evaluating the Efficacy and Safety of S1-OXALIPLATIN in Patients of Unresectable and Metastatic Biliary Tract Malignancies with Hyperbilirubinemia - A Phase II Trial (SOX-GB)
Gaurav Prakash, MD,Harshith Sai Koneti, MD,Naveen Yadav, MD,Lakshay Tyagi, MD
Submission received: 2026-09-11 / Accepted: 2026-09-14 / Published: 2026-09-24
Abstract
Background
Gemcitabine-cisplatin, standard first-line therapy for advanced biliary tract cancer (BTC), is precluded by cisplatin nephrotoxicity in patients with acute kidney injury or persistent hyperbilirubinemia after biliary drainage, or when drainage is infeasible. S-1, an oral fluoropyrimidine, plus oxaliplatin (SOX) avoids renal toxicity and is established in other gastrointestinal cancers. Both agents can be dosed safely in hepatic/renal dysfunction, making SOX rational for this treatment-limited, often late-presenting BTC population.
Methods
SOX-GB is a single-arm phase II trial (PGIMER Chandigarh; CTRI/2026/04/108053) enrolling chemotherapy-naive adults (18-75y) with confirmed, measurable (RECIST 1.1) unresectable/metastatic BTC, ECOG PS 0-2, and hyperbilirubinemia (>2.75xULN) post-drainage or drainage infeasible. Treatment: S-1 20mg/m2 twice daily, days 1-14, plus oxaliplatin 85-100mg/m2 IV day 1, q21 days, up to 8 cycles. Primary endpoint: disease control rate (DCR; CR+PR+SD, RECIST 1.1) at 3 months. Secondary endpoints: PFS, bilirubin/CA19.9 kinetics, toxicity. Sample size uses Simon's optimal two-stage design (alpha=5%, power=80%; p0=5%, p1=20%): stage 1, 10 patients (stop if 0 responses); stage 2, total 29 (>=4 responses needed). Trial registration: CTRI/2026/04/108053
Results
As of the data cut-off, 21 patients had been enrolled and had started SOX. Among 16 response-evaluable patients, disease control occurred in 5 (2 PR, 3 SD); the remaining had progressive disease/ had dropped out due to poor performance status. Two discontinued early for poor performance status; one developed treatment-related cholangitis with AKI and altered sensorium, transitioning to palliative care. Cholangitis (n=3) and ascites (n=2) were the main toxicities; no treatment-related deaths occurred. The stage 1 activity threshold (>=1 response) was met; accrual continues toward the 29-patient stage 2 cohort.
Conclusion
Preliminary data suggest that SOX is feasible and tolerable, with an early disease-control signal in this hyperbilirubinemic, treatment-limited BTC population that is ineligible for standard chemotherapy. Enrolment in the study continues; mature DCR, PFS, and bilirubin/CA19.9 kinetics data are awaited.