Sintilimab plus nab-paclitaxel as second-line treatment for advanced biliary tract cancer: study protocol for an investigator-initiated phase 2 trial (NapaSinti trial).

Background: Biliary tract cancer (BTC) is a relatively rare but highly aggressive malignancy. However, there is currently no satisfactory second-line regimen for patients without specific genetic mutations. Nanoparticle albumin-bound paclitaxel, also known as nab-paclitaxel (Abraxane, Bristol Myers Squibb), has shown activity in patients with BTC. Studies investigating the immunogenic features of BTC suggested that checkpoint inhibition may lead to antitumor immune responses. In recent years, improved survival has been observed in patients treated with chemotherapy combined with immunotherapy across multiple cancer types, including BTC. This clinical trial aims to evaluate the efficacy and safety of second-line sintilimab in combination with nab-paclitaxel in advanced BTC patients.

Methods: The NapaSinti trial is a prospective, nonrandomized, open-label, phase 2 study conducted at a tertiary hospital in Chengdu, China. Eligible patients are those with histologically or cytologically confirmed locally advanced non-resectable or metastatic adenocarcinoma in the biliary tract (including intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, and gallbladder cancer), aged between 18 and 75 years, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, who have experienced disease progression after prior gemcitabine- or fluorouracil-based chemotherapy and have not received taxane or immune checkpoint inhibitor treatment. Enrolled patients will receive intravenous administration of sintilimab 200 mg on day 1 and nab-paclitaxel 125 mg/m2 on days 1 and 8, every three weeks. The primary endpoint is the objective response rate (ORR), while the secondary endpoints include overall survival (OS), progression-free survival (PFS), and safety. Exploratory objectives aim to identify biomarkers and molecular signatures for predicting response or prognosis. Using Simon's two-stage design, a total of 63 participants will be enrolled in the study. This trial was initiated in March 2022 in China.

Discussion: The NapaSinti trial evaluates the efficacy and safety of second-line sintilimab plus nab-paclitaxel for advanced biliary tract cancer. Additionally, the trial provides an opportunity for translational research.

Trial Registration: Chinese Clinical Trial Registry ChiCTR2100052118. Registered October 19, 2021.