L1-CAM is commonly expressed in testicular germ cell tumours.

Germ cell tumors (GCT) are curable cancers, but 10-15% of patients with metastatic disease fail cisplatinbased first-line therapy. While therapeutic options have increased for various other cancers no therapeutic targets have emerged in cisplatin-refractory GCT. L1 cell adhesion molecule (L1-CAM) is commonly expressed in human malignancies and therefore a potential target, however its expression in GCT has not been studied so far. The aim of our study was to describe the expression of L1-CAM in a large series of testicular GCT. Immunohistochemistry was used to study L1-CAM expression in 325 testicular GCT, including 94 mixed GCT. L1-CAM expression was found in 38% of seminomas, 50% of yolk sac tumors, 19% of teratomas, 50% of choriocarcinomas, 67% of embryonal carcinoma. L1-CAM was expressed in 45% of germ cell neoplasias in situ but not in normal tissue. This common L1-CAM expression in testicular GCT might serve as an immunotherapeutic target in the future.