A phase II clinical study of stereotactic radiotherapy (SRT) combined with chemotherapy and tislelizumab for the treatment of metastatic nasopharyngeal carcinoma.

Abstract

e18020 Background: In general, immune checkpoint inhibitors combined with chemotherapy can benefit patients with metastatic nasopharyngeal cancer (mNPC), but immunotherapy is still ineffective in some patients. Previously, studies have verified the safety and efficacy of local radiotherapy in newly diagnosed mNPC patients. In addition, radiotherapy can also enhance immune responses by changing the tumor microenvironment. This study preliminarily explores the efficacy and safety of stereotactic radiotherapy (SRT) combined with chemotherapy and tislelizumab (PD-1 inhibitor) in mNPC. Methods: A prospective, single-arm, single-center phase II study, thirty-seven cases were enrolled with pathological diagnosis of mNPC. The metastatic lesions received SRT (adjusted individually based on the size, location of the metastatic lesions, and the distance to adjacent critical organs) along with 4-6 cycles of chemotherapy combined with immunotherapy. For newly diagnosed metastatic patients, nasopharyngeal and metastatic lymph node GTV irradiation was performed after 4-6 cycles of chemotherapy and immunotherapy, followed by immunotherapy maintenance therapy until disease progression or for up to 2 years. The primary endpoint was progression-free survival (PFS) within the radiation field, and the secondary endpoints were objective response rate (ORR) and safety. Results: From October 2022 to June 2025, a total of 38 eligible patients were screened, which 30 patients underwent metastatic radiotherapy and 8 patients did not undergo metastatic radiotherapy due to personal reasons. Among the 38 patients, the mean age was 56 years and predominantly male (84.2%), meanwhile 65.8% patients were newly diagnosis with metastases. The median follow-up time for the 30 patients was 21.4 months, and the median PFS in target lesions has not yet been reached. 12 -month PFS rate in target lesions is 96% [89%-100%, 95% CI] and 24 -month PFS rate in target lesions is 78% [61%-100%, 95% CI]. After SRT for metastatic lesions, the efficacy could be evaluated in 27 patients, including 17 (63%, 95%CI 42%-80%) patients with CR, 9 patients with PR (33%, 95%CI 17%-54%), and 1(4%, 95%CI 0.19%-21%) patient with SD. The most common TEAEs are still chemotherapy related. Immune-related adverse reactions are mainly dermatitis, pneumonia, hepatitis, and hypothyroidism, all of which are mild. Conclusions: For patients with mNPC, receiving SRT for metastatic lesions along with chemotherapy and immunotherapy holds excellent prospects for local disease control. Clinical trial information: NCT05652192 .