Efficacy and safety of sintilimab plus bevacizumab in metastatic nasopharyngeal carcinoma after failure of platinum-based chemotherapy: an open-label phase 2 study

There are limited treatment options for patients with metastatic nasopharyngeal carcinoma (mNPC) after failure of platinum-based chemotherapy. In this trial, we assessed the efficacy and safety of sintilimab plus bevacizumab in patients with mNPC where platinum-based chemotherapy has been ineffective.This was a single-centre, open-label, single-arm, phase 2 trial in Guangzhou, China for patients with mNPC progressed after at least one line of systemic therapy. Eligible patients were between 18 and 75 years old, were histologically confirmed differentiated or undifferentiated non-keratinized NPC, were ineffective after platinum-based chemotherapy, and they had at least one measurable metastatic lesion assessed with Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST V.1.1) by investigators and unsuitable for local surgery or radiotherapy. Key exclusion criterion was previous treatment with anti-PD-1/PD-L1 antibodies plus anti-VEGF antibodies and high risk of hemorrhage or nasopharyngeal necrosis. Patients were enrolled and received sintilimab (200 mg) plus bevacizumab (7.5 mg/kg) intravenously every 3 weeks. Intention-to-treat population was included in primary endpoint analyses and safety analyses. The primary endpoint was objective response rate (ORR) assessed by investigators following the guidelines of RECIST V1.1. Key secondary endpoints were progression-free survival (PFS), overall survival (OS), duration of response (DOR), and safety. This trial is registered with ClinicalTrials.gov (NCT04872582).Between July 29, 2021 and August 16, 2022, 33 patients were enrolled. Median age was 46 years (range, 18-64 years), and 63.6% of patients had previously received two or more lines of chemotherapy for metastatic disease. Median follow-up was 7.6 months (range, 4.1-17.5 months). ORR was 54.5% (95% CI, 36.4-71.9%) with 3 complete responses (9.1%) and 15 partial responses (45.5%). Median PFS was 6.8 months (95% CI, 5.2 months to not estimable). Median DOR was 7.2 months (95% CI, 4.4 months to not estimable). Median OS was not reached. The most common potential immune-related adverse event (AE) was Grade 1-2 hypothyroidism (42.4%). Treatment-related grade 3 or 4 AEs occurred in 7 patients (21.2%), including nasal necrosis (3/33), hypertension (1/33), pruritus (1/33), total bilirubin increased (1/33) and anaphylactic shock (1/33). No treatment-related deaths and severe epistaxis occurred.This phase 2 trial showed that sintilimab plus bevacizumab demonstrated promising antitumour activity and manageable toxicities in patients with mNPC after failure of platinum-based chemotherapy. Further trials are warranted, and the detailed mechanisms need to be elucidated.The Guangdong Basic and Applied Basic Research Foundation, the National Natural Science Foundation of China, the Natural Science Foundation of Guangdong Province, and the Science and Technology Planning Project of International Cooperation of Guangdong Province.