Analysis of Plasma Epstein-Barr Virus DNA and Clinical Outcomes to Pembrolizumab or Chemotherapy in Recurrent/Metastatic Nasopharyngeal Cancer in KEYNOTE-122

Cancer Med. 2026 Feb;15(2):e71496. doi: 10.1002/cam4.71496.

Abstract

Background: Plasma Epstein-Barr virus (EBV) DNA has clinical utility for prognosis, recurrence, surveillance, and treatment response in nasopharyngeal carcinoma (NPC). This exploratory analysis evaluated associations between plasma EBV DNA load and clinical outcomes in participants treated with pembrolizumab or chemotherapy in the phase 3 KEYNOTE-122 trial (NCT02611960).

Methods: Participants with platinum-pretreated, histologically confirmed, EBV-positive, recurrent/metastatic NPC were randomly assigned (1:1) to pembrolizumab 200 mg intravenously every 3 weeks (≤ 35 cycles) or standard of care (SOC; investigator's choice of capecitabine, gemcitabine, or docetaxel). Associations between baseline plasma EBV DNA load as a continuous variable and plasma EBV DNA fold change at cycle 2 day 1 (C2D1), with clinical outcomes (progression-free survival [PFS], overall survival [OS], and objective response rate [ORR]) were evaluated within each treatment arm. Nominal significance was prespecified at 0.05 for 1-sided p values.

Results: Of 228 treated participants, 215 (94.3%) had evaluable baseline plasma EBV DNA load data (pembrolizumab, 111; SOC, 104). Baseline plasma EBV DNA load was negatively associated with PFS and OS for pembrolizumab and SOC (both p < 0.005) but not ORR (p = 0.105, pembrolizumab; p = 0.473, SOC). Larger decreases in plasma EBV DNA load at C2D1 relative to baseline were associated with improved PFS, OS, and ORR for pembrolizumab and SOC (p ≤ 0.005).

Conclusions: Higher baseline plasma EBV DNA load was negatively associated with outcomes in participants with NPC treated with pembrolizumab or SOC. These findings provide additional support for plasma EBV DNA as a prognostic biomarker for NPC.

Trial registration: ClinicalTrials.gov, NCT02611960.

Keywords: Epstein–Barr virus; biomarkers; chemotherapy; nasopharyngeal carcinoma; pembrolizumab.

Publication types

  • Randomized Controlled Trial
  • Clinical Trial, Phase III
  • Multicenter Study

MeSH terms

  • Adult
  • Aged
  • Antibodies, Monoclonal, Humanized* / administration & dosage
  • Antibodies, Monoclonal, Humanized* / adverse effects
  • Antibodies, Monoclonal, Humanized* / therapeutic use
  • Antineoplastic Combined Chemotherapy Protocols* / adverse effects
  • Antineoplastic Combined Chemotherapy Protocols* / therapeutic use
  • Capecitabine / administration & dosage
  • DNA, Viral* / blood
  • Deoxycytidine / administration & dosage
  • Deoxycytidine / analogs & derivatives
  • Docetaxel / administration & dosage
  • Docetaxel / therapeutic use
  • Epstein-Barr Virus Infections* / complications
  • Epstein-Barr Virus Infections* / drug therapy
  • Epstein-Barr Virus Infections* / virology
  • Female
  • Gemcitabine
  • Herpesvirus 4, Human* / genetics
  • Humans
  • Male
  • Middle Aged
  • Nasopharyngeal Carcinoma* / blood
  • Nasopharyngeal Carcinoma* / drug therapy
  • Nasopharyngeal Carcinoma* / mortality
  • Nasopharyngeal Carcinoma* / virology
  • Nasopharyngeal Neoplasms* / blood
  • Nasopharyngeal Neoplasms* / drug therapy
  • Nasopharyngeal Neoplasms* / mortality
  • Nasopharyngeal Neoplasms* / pathology
  • Nasopharyngeal Neoplasms* / virology
  • Neoplasm Recurrence, Local* / drug therapy
  • Neoplasm Recurrence, Local* / virology
  • Treatment Outcome
  • Viral Load

Substances

  • Antibodies, Monoclonal, Humanized
  • pembrolizumab
  • DNA, Viral
  • Deoxycytidine
  • Gemcitabine
  • Docetaxel
  • Capecitabine

Associated data

  • ClinicalTrials.gov/NCT02611960

Grants and funding