A multicenter randomized controlled trial (RCT) of adjuvant chemotherapy (CT) in nasopharyngeal carcinoma (NPC) with residual plasma EBV DNA (EBV DNA) following primary radiotherapy (RT) or chemoradiation (CRT).

Abstract

6002 Background: The benefit of adjuvant CT in NPC is unclear. Post-RT EBV DNA predicts poor survival and may be a biomarker of subclinical residual disease. We conducted a biomarker driven RCT using post-RT EBV DNA to select high risk NPC patients (pts) for adjuvant CT while sparing low risk pts from unnecessary toxicity. Methods: Eligible pts had biopsy proven NPC of AJCC (6th Ed) stage IIB-IVB, detectable EBV DNA ( > 0 copy/ml) at 6-8 weeks post-RT, no persistent locoregional disease or distant metastasis, ECOG 0 or 1, and adequate organ function. Pts were randomized with stratification for primary therapy (RT Vs CRT) and tumor stage (II/III Vs IV) to arm A (adjuvant cisplatin 40 mg/m2 and gemcitabine 1000 mg/m2, both given on D1+8 q3w x 6 cycles) or arm B (clinical follow-up). Primary endpoint was relapse free survival (RFS). With a hazard ratio (HR) of 2, 100 pts were required with a power of 0.8 and an alpha at 0.05. Results: From 9/2006 to 7/2015, 789 pts consented for EBV DNA screening, 218 (27.6%) pts had detectable EBV DNA, and 104 (13.2%) pts were randomized (arm A: 52; arm B: 52). The two arms were well balanced in baseline characteristics. 84.6% received prior neoadjuvant and/or concurrent CT and all received curative RT. Staging distribution: IIB 27.9%, III 37.5%, IVA 19.2%, IVB 15.4%. 8 pts refused adjuvant CT after randomization. Overall 69% and 50% completed 3 and 6 cycles of adjuvant CT respectively. After median follow up of 6.5 years (yr), the 3-yr and 5-yr survival outcomes were summarized in Table. Conclusions: In NPC pts who had residual EBV DNA after curative RT/CRT, adjuvant CT with cisplatin-gemcitabine did not improve survival. Clinical trial information: NCT00370890. [Table: see text]