Expression of Cancer testis Antigens in Tumor-adjacent Normal Liver Predicts Post-resection Recurrence of Hepatocellular Carcinoma

Background: High recurrence rates after resection of hepatocellular cancer (HCC) with curative intent and lack of effective therapy for advanced disease impair clinical outcomes of HCC. Cancer/testis antigens (CTAs) are suitable targets for cancer immunotherapy if selectively expressed in tumor cells. The aims of this study were to establish a panel of CTAs that are frequently and selectively expressed in tumors of HCC-patients, and to investigate whether CTAs might be expressed in tumor-free liver tissues of HCC-patients.Methods: Surgically-resected tumor and paired tumor-free (TFL) tissues of HCC patients (n=100), healthy livers (n=21), and other healthy tissues (n=22 different tissues) were assessed for mRNA expression of 49 carefully selected CTAs by RT-qPCR. Protein expression of 5 CTAs was determined by immunohistochemistry (n=78).Results: Twelve CTAs were expressed at mRNA level in ≥10% of HCC-tumor tissues and not in healthy tissues except testis. In tumors, mRNA and protein of ≥ 1 CTA was expressed in 78% and 71% of HCC-patients, respectively. In TFL, CTA mRNA and protein expression was found in 45% and 30% of HCC-patients, respectively. Interestingly, CTA expression in TFL was an independent negative prognostic factor for HCC-recurrence and survival after tumor resection.Conclusions: We established a novel panel of 12 testis-restricted CTAs expressed in tumors of most HCC-patients, that can be safely used for immunotherapeutic targeting of HCC. The increased risk of HCC recurrence in patients with CTA expression in TFL suggests that CTA-expressing (pre-)malignant cells may be a source of HCC recurrence. Therefore, immunotherapeutic targeting of these antigens should be considered as adjuvant therapy to prevent HCC-recurrence after tumor resection. Lay summary:Expression of multiple defined cancer testis antigens in non-cancerous liver tissue is associated with significantly increased cancer-recurrence and worse patient survival after tumor resection. We propose that immunotherapeutic targeting of these antigens may prevent HCC recurrence after tumor resection.