Durvalumab plus gemcitabine/cisplatin/nab-paclitaxel in resectable biliary tract cancer: A phase II, single-arm, open-label study (DurGAP).

e16260 Background: Biliary tract cancer (BTC) presents a formidable challenge, marked by its aggressive nature and dismal prognosis. While surgical resection remains the lone potentially curative option, 5-year survival rates have plateaued below 50%, largely due to high rates of recurrences and metastases. Given these sobering statistics, the imperative for neoadjuvant therapy to enhance outcomes is evident. Building upon the success of the TOPAZ-1 trial, which established durvalumab in combination with gemcitabine and cisplatin as a standard regimen for advanced BTC, this study seeks to assess the safety and efficacy of incorporating neoadjuvant durvalumab alongside gemcitabine, cisplatin, and Nab-paclitaxel for resectable BTC. Methods: Resectable, treatment-naïve BTC patients (pts) were enrolled and administered 3 cycles of neoadjuvant durvalumab (1000mg, iv, d1, q3w) + GAP (gemcitabine 1000mg/m 2 , cisplatin 25mg/m 2 , Nab-paclitaxel 100mg/m 2 , d1, d8, 21d cycle). Primary endpoints included assessing Adverse Events (AEs) and Objective Response Rate (ORR). Secondary endpoints comprised R0 resection rate, Recurrence-Free Survival (RFS), Overall Survival (OS). Results: Between Feb, 2023 to Jan, 2024, a total of 24 patients were enrolled, 12 (50.0%) were male, all with ECOG 0 and 18 (75.0%) presenting with N1 status. Median age: 65 years. Primary sites: intrahepatic (50.0%), extrahepatic (33.3%), gallbladder (16.7%). Median follow-up: 8.75 months; all pts received ≥2 neoadjuvant cycles. The ORR was 62.5%, with all 15 pts demonstrating partial responses (PR). The DCR was 87.5% with 15 PR and 6 stable disease (SD) responses. The most common treatment-related adverse events (TRAEs) were increased ALT/AST (28.6%), anemia (21.8%), hypoalbuminemia (16.0%). Grade ≥3 TRAEs occurred in 2 (8.3%) pts. 13 pts underwent resection, achieving R0 resection in 12 (92.3%) of cases, comprising 10 PR, 2 SD, and 1 pt deemed eligible for surgery post-assessment despite a PD response. 11 pts did not undergo resection, with reasons including patient refusal (4 PR, 1 SD), not meeting resection criteria (2 PD), lost to follow-up (1 PR, 1 SD), and still under active follow-up (2 SD). Conclusions: Neoadjuvant durvalumab combined with gemcitabine/cisplatin/Nab-paclitaxel demonstrated a promising ORR and DCR, with a tolerable safety profile, warranting further investigations in a larger cohort. Clinical trial information: NCT05640791 .