Combining Radiotherapy with Chemotherapy and Immunotherapy as First-Line Treatment for De Novo Metastatic Nasopharyngeal Carcinoma: A Dual-Center Retrospective Analysis

Abstract

Local regional radiotherapy combined with systemic chemotherapy significantly improves the prognosis of patients with metastatic nasopharyngeal carcinoma (NPC). Immunochemotherapy has become the first-line treatment for initial metastatic NPC. This study evaluated the safety and efficacy of local regional radiotherapy combined with immunochemotherapy as the first-line treatment of metastatic NPC. Patients with histologically proven de novo metastatic NPC who received immunotherapy and chemotherapy followed by local-regional radiotherapy were included from 2 cancer centers. Toxicity and treatment response were assessed using CTCAE 5.0 and RECIST 1.1, respectively. Overall survival (OS) and progression free survival (PFS) were analyzed using the Kaplan-Meier method. From 2019 to 2021, a total of 16 patients were retrospectively analyzed. The median age was 44.5-year-old (range 16-76). Patients with ≥3 metastatic lesions accounts for 58.8%. Bone metastasis was the most common metastatic site. The chemotherapy regimens were paclitaxel/gemcitabine and cisplatin. Toripalimab, camrelizumab and sintilimab were used for immunotherapy. All patients completed the local regional radiotherapy with 69.96Gy for primary nasopharyngeal tumor and positive lymph nodes, 60.06Gy for high-risk region and 50ཞ54.45Gy for low-risk region. Seven patients underwent radiotherapy for metastatic lesions. The median follow-up was 20.5 months (range 6-38 months). Two-year OS was 100%. Three patients experienced distant progression. One-year and 2-year PFS rate was 93.8% and 76.7%, respectively. After combination of chemotherapy and immunotherapy, the overall response rate (ORR) was 93.7% with a complete response (CR) of 6.3%. At the end of radiotherapy, the ORR was 100%. Nine patients (56.3%) achieved CR. Radiotherapy related acute severe (grade 3 or higher) toxicity was dermatitis (1/16, 6.3%) and mucositis (2/16, 12.5%). Immunotherapy related hypophysitis and capillary hyperplasia was 6.3% and 6.3%, respectively. No long-term toxicity was observed. Loco-regional radiotherapy provided a promising efficacy with modest toxicity for patients with metastatic nasopharyngeal carcinoma who received immunochemotherapy.