Novel Anti- <i>BNLF2b</i> Antibody Screening and Early Detection of Nasopharyngeal Carcinoma

Importance: Tests for total antibodies specific to the Epstein-Barr virus (EBV) BNLF2b gene-encoded putative protein (P85-Ab) have shown high sensitivity and specificity for detecting newly diagnosed nasopharyngeal carcinoma (NPC). However, independent validation of these findings is important before considering clinical application. Objective: To compare the performance of P85-Ab testing for NPC detection with a combined Epstein-Barr virus-specific IgA antibody score and a circulating EBV DNA algorithm. Design, Setting, and Participants: This was a multicenter case-control study conducted from July 2010 to December 2014 at 6 medical centers in northern and central Taiwan. Participants were patients with NPC and controls who all provided blood samples for EBV biomarker testing. Data were analyzed from January 2025 to January 2026. Exposures: Total antibodies specific to P85-Ab. For comparison, EBV viral capsid antigen/nuclear antigen 1 (VCA-IgA/EBNA1-IgA) antibody score and the circulating EBV DNA algorithm results were evaluated from the same archived blood specimens collected at enrollment. Results: The analysis included 892 patients with NPC (mean [SD] age, 48.6 [11.1] years; 191 females [21.4%] and 701 males [78.6%]) and 1804 individuals in the control group (mean [SD] age, 48.1 [12.2] years; 542 females [30.0%] and 1262 males [70.0%]). P85-Ab demonstrated a sensitivity of 92.5% (95% CI, 90.7%-94.3%) and specificity of 98.7% (95% CI, 98.2%-99.2%), higher than the EBV VCA-IgA/EBNA1-IgA score (sensitivity, 88.4%; specificity, 94.9%) and comparable to the circulating EBV DNA algorithm (sensitivity, 93.2%; specificity, 98.1%). Sensitivity for early-stage NPC was higher for P85-Ab (93%) than for the other 2 methods (87%). P85-Ab performance remained high across age, sex, region, ethnicity, family history, and smoking subgroups. At NPC incidence rates of 20 to 100 per 100 000 person-years, the numbers needed to screen were similar across the 3 approaches: 5656 and 1131 for EBV VCA-IgA/EBNA1-IgA; 5365 and 1073 for EBV DNA; and 5405 and 1081 for P85-Ab. Positive predictive value (PPV) was 0.4% for the EBV antibody score, 1.0% for the EBV DNA algorithm, and 1.4% for the P85-Ab test; at an incidence of 100 per 100 000, the PPVs increased to 1.7%, 4.7%, and 6.6%, respectively. Conclusions and Relevance: This multicenter case-control study found that P85-Ab testing had high sensitivity and specificity for early detection of NPC, with performance better than or comparable to existing EBV-based screening methods. These findings support the potential use of P85-Ab testing as a practical biomarker for population-based NPC screening.