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

6031 Background: 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 mNPC patients where platinum-based chemotherapy has failed. Methods: This was a single-center, open-label, single-arm, phase II trial for mNPC patients progressed after at least one line of systemic therapy. Patients were enrolled and received sintilimab (200 mg) plus bevacizumab (7.5mg/kg) intravenously every 3 weeks. The primary end point was objective response rate (ORR) assessed by investigators following the guidelines of RECIST 1.1. Key secondary end points were progression-free survival (PFS), overall survival (OS), duration of response (DOR), and safety. This trial is registered with ClinicalTrials.gov (NCT04872582). Results: Thirty-three 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 AE was grade 1-2 hypothyroidism (42.4%). Treatment-related grade 3 or 4 adverse events (AEs) occurred in 7 patients (21.2%), including nasal necrosis (9%), hypertension (3%), pruritus (3%), total bilirubin increased (3%) and anaphylactic shock (3%). No treatment-related deaths and severe epistaxis occurred. Conclusions: This phase II trial showed that sintilimab plus bevacizumab demonstrated promising antitumor activity and manageable toxicities in mNPC patients after failure of platinum-based chemotherapy. Clinical trial information: NCT04872582 .