154P - Neoadjuvant chemotherapy plus tislelizumab followed by adjuvant tislelizumab for locoregionally advanced nasopharyngeal carcinoma (NPC): A single-arm, phase II trial

Background

Prognosis of NPC with T4 or N3 remains unsatisfactory due to high-risk of distant metastasis. More effective treatment strategies are needed for these patients. GP plus immune checkpoint blockade regimen has been shown to improve the survival in recurrent or metastatic NPC We investigated the efficacy and safety of neoadjuvant with GP plus tislelizumab followed by concurrent chemoradiotherapy, and adjuvant treatment with tislelizumab, an anti-PD-1 monoclonal antibody, in previously untreated T4 or N3 NPC.

Methods

In this phase II, single-arm study, eligible patients aged 18-70 yrs who were diagnosed with stage IVa (AJCC 8^th) non-keratinizing nasopharyngeal received neoadjuvant therapy with gemcitabine (1000mg/m² on day 1,8), cisplatin (25 mg/m² on day 1-3) and tislelizumab (200mg) Q3W for 2 cycles followed by concurrent IMRT and cisplatin (100 mg/m²) Q3W during radiotherapy, then followed by adjuvant therapy with tislelizumab (200 mg) Q3W for 13 cycles. The primary endpoint was 2-years progression-free survival (PFS). The secondary endpoint included objective response rate (ORR), overall survival (OS), progression-free survival (PFS) and safety. This study planned to enroll 50 patients in 2 years.

Results

A total of 27 patients were enrolled from Sep. 2021 to Sep. 2022. 23 patients were evaluable for response assessment to neoadjuvant therapy with a median age of 49 (24-66) yrs and 82.6% (n=19) of male. According to RECIST1.1, 20 (87.0%) patients had objective response to neoadjuvant treatment, including 2 (8.7%) patient with CR, 18 (78.3%) patients with PR. The other 3 patients had SDa with a definition of tumor shrinkage occured and below a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters. The incidence of adverse events of grade 3 or 4 was in 52.2% (12/23) patients, including nausea (7 [30.4%]) leukopenia (3 [13.0%]) neutropenia (2 [8.7%]) and hepatotoxicity (2 [8.7%]). Long-term efficacy is awaited.

Conclusions

Neoadjuvant with tislelizumab plus GP and adjuvant tislelizumab treatment achieved an impressive ORR with manageable toxicities. Further follow-up is needed to confirm the long-term efficacy.

Clinical trial identification

NCT05448885.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.