YAP1 amplification as a prognostic factor of definitive chemoradiotherapy in nonsurgical esophageal squamous cell carcinoma.

BACKGROUND: Definitive chemoradiation therapy (dCRT) is the standard treatment for patients with nonsurgical esophageal squamous cell carcinoma (ESCC), yet patients have demonstrated great variations in their responses to dCRT and inevitably progressed following treatment. METHODS: To identify prognostic biomarkers, we performed targeted next-generation sequencing of 416 cancer-related genes on primary tumors from 47 nonsurgical ESCC patients prior to dCRT treatment. The association between genetic alterations and patients' local recurrence-free survival (LRFS), progression-free survival (PFS), and overall survival (OS) was analyzed. RESULTS: TP53 (78% of patients), NOTCH1 (32%), ARID1A (13%), FAT1 (13%), and CDKN2A (13%) were commonly mutated in ESCC patients, while gene amplifications frequently occurred in MCL1 (36%), FGF19 (34%), MYC (32%), CCND1 (27%), ZNF217 (15%), CDKN2A (13%), and YAP1 (11%). Univariate and multivariate analyses of clinical factors and genetic alterations indicated that sex is an independent prognostic factor, with males tending to have better LRFS (hazard ratio [HR], 0.25; 95%CI, 0.08-0.77, P = .015) and progression-free survival (PFS) (HR, 0.35; 95%CI, 0.13-0.93, P = .030) following dCRT. Meanwhile, YAP1 amplification (n = 7) was an adverse prognostic factor, and patients with this alteration demonstrated a tendency toward worse outcomes with shorter LRFS (HR, 4.06; 95%CI, 1.26-13.14, P = .019) and OS (HR, 2.78; 95%CI, 0.95-8.17, P = .062). In a subgroup analysis, while sex and M-stage were controlled, a much stronger negative effect of YAP1 amplification vs wild-type in LRFS was observed (log-rank P = .0067). CONCLUSION: The results suggested that YAP1 amplification is a potentially useful biomarker for predicting treatment outcomes and identifying patients with a high risk of relapse who should be closely monitored.