Biliary tract cancer (BTC) is a rare and aggressive malignancy with a grim prognosis, even for patients who undergo curative surgery. Despite surgical resection, the recurrence rate remains high, and 5-year overall survival (OS) rates are <10%. The current standard of care for adjuvant therapy of BTC after surgical resection is capecitabine. This is based on the UK BILCAP trial (EudraCT Number: 2005-003318-13), which showed a survival benefit for capecitabine in patients with resected biliary cancer despite not meeting its primary endpoint of improving OS in the intention-to-treat population. To explore more effective options, the ADJUBIL trial (NCT05239169) investigated the efficacy and safety of a combination of immune checkpoint inhibitors, durvalumab and tremelimumab, with or without capecitabine, in the adjuvant setting for resectable BTC.
The ADJUBIL trial was an open-label, multicenter, phase 2 study conducted in Germany. Patients with biliary tract cancer who had not received prior treatment and underwent curative surgery were randomized 1:1 into 2 groups: arm A received durvalumab, tremelimumab, and capecitabine, and arm B received durvalumab and tremelimumab without capecitabine. Durvalumab was administered at 1500 mg every 4 weeks for up to 12 months, whereas tremelimumab was given as a single 300-mg dose on day 1 of cycle 1. In arm A, capecitabine was administered at 1250 mg/m² twice daily on days 1 to 14 of each 21-day cycle for up to 8 cycles. The primary endpoint was recurrence-free survival (RFS) at 12 months, with secondary endpoints including OS and safety.
A total of 40 patients with resectable BTC (ECOG 0 or 1) were included in this study. The median age was 65 years in patients treated with capecitabine and 62 years in those who were not. At a median follow-up of 13.8 months, the results demonstrated that durvalumab and tremelimumab without capecitabine achieved RFS at 12 months (57.9%) compared with the combination with capecitabine (52.4%). Median RFS was 17.0 months for patients not utilizing capecitabine and 15.0 months for those who were utilizing capecitabine. One-year OS rates were comparable between the 2 arms, with 85% among patients treated with capecitabine and 84% in those who were not. However, patients treated with capecitabine had a higher toxicity burden, with 67% of patients experiencing at least 1 grade ≥3 adverse event, compared with 53% in patients treated with capecitabine. Similarly, treatment-related grade ≥3 adverse events were more frequent in patients treated with capecitabine (48%) compared with those who were not (32%).
The findings suggest that the addition of capecitabine to durvalumab and tremelimumab may be less favorable in terms of disease recurrence and increased toxicities for adjuvant therapy in the treatment of resectable BTC. The ADJUBIL trial demonstrated that durvalumab in combination with tremelimumab without capecitabine offers promising RFS with a manageable safety profile, and warrants further research.
Goetze TO, Vogel A, Gonzalez-Carmona, MA, et al. ADJUBIL: a phase II study of immunotherapy with durvalumab and tremelimumab in combination with capecitabine or without capecitabine in adjuvant situation for biliary tract cancer—the IKF/AIO-ADJUBIL trial. Presented at: 2025 ASCO Annual Meeting. May 30-June 3, 2025; Chicago, IL. Poster 422.
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