Response-adapted therapy for locally advanced nasopharyngeal carcinoma based on clinical response and circulating Epstein-Barr virus DNA level post induction chemotherapy.

Abstract

TPS6112 Background: For locally advanced nasopharyngeal carcinoma (NPC), the mainstay treatment is cisplatin-based concurrent chemoradiation (CCRT). Recent phase III clinical trials have demonstrated that induction chemotherapy (ICT) plus CCRT, compared with CCRT alone, further improved progression-free survival (PFS). However, not every patient has good response to ICT. Evidence has accumulated that those with poor response to ICT, or those with detectable Epstein-Barr Virus (EBV) DNA post ICT, correlated with poorer PFS. In addition, real-time monitoring of plasma EBV DNA response adds prognostic information, and has the potential utility for risk-adapted treatment intensification in NPC. The aim of this study is to clarify whether response-adapted strategy based on clinical efficacy and EBV DNA response confers survival benefit to patients with locally advanced NPC. Methods: This is an open-label, 3-arm, phase II study. Patients with pathologically confirmed, locally advanced NPC (III-IVA, excluding T3N0M0, 8th AJCC staging system), with pretreatment detectable plasma EBV DNA level and ECOS PS 0-1 were eligible. Patients will receive one cycle of GP-based ICT. After one cycle of ICT, plasma EBV DNA and head and neck MR are performed. Based on clinical efficacy (evaluated per RECIST 1.1 criteria) and changes of plasma EBV DNA after one cycle, patients will be divided into three arms. Patients with good response (Arm A: Early Responders, undetectable EBV DNA level and CR/PR) will directly receive CCRT. Patients with intermediate response (Arm B: Intermediate Responders, detectable EBV DNA and CR/PR/decreased SD; or undetectable EBV DNA yet without CR/PR) will be randomized to experiment subgroup (GP combined with Toripalimab for two additional cycles then CCRT and maintenance Toripalimab treatment) and standard subgroup (GP for two additional cycles then CCRT). Patients with poor response (Arm C: Treatment Resistant, increased EBV DNA level, or PD/enlarged SD) will be switched to TP regimen combined with Toripalimab, followed by CCRT and maintenance Toripalimab treatment. Sample size calculation is based on 2-year PFS rate for arm B as the primary endpoint (one-sided α = 0.10, power = 0.80). Our target sample size is estimated to be 198-240, among them 168 for arm B. Secondary endpoints include adverse events determined by CTCAE v5.0, ORR at 3 months post-CRT, 2-year locoregional recurrence-free survival (LRFS) rate, 2-year distant metastasis-free survival (DMFS) rate, 2-year overall survival (OS) rate, as well as quality of Life for arm B. Exploratory endpoints include 2-year PFS rate, LRFS rate, DMFS rate, OS rate, ORR at 3 months post-CRT, adverse effects, and quality of life for arm A and arm C. This trial opened to accrual in July 2022 and the recruitment is ongoing. Clinical trial information: NCT05628922 .