Persistent CD30 expression by embryonal carcinoma in the treatment time course: prognostic significance of a worthwhile target for personalized treatment

Purpose: CD30 is expressed by untreated embryonal carcinoma, supporting the rationale for a targeted approach. However, the reported chemotherapy induced switching off of CD30 noted on immunohistochemistry may affect its therapeutic potential for disease relapse. We evaluated persistent CD30 expression and its prognostic meaning in cases of post-chemotherapy residual disease. Materials and Methods: Paraffin blocks of surgical samples that yielded nonteratomatous viable cells after 1 or more cisplatin based chemotherapy treatments were retrieved and reassessed by 2 pathologists blinded to the study purpose. Multivariable analysis was done for prespecified factors. Results: A total of 49 cases of pure embryonal carcinoma or mixed germ cell tumor from August 1991 to August 2012 had full clinical data and suitable tissue available for analysis. Of the 35 cases (71.4%, 95% CI 56.7-83.4) with preserved CD30 positivity 14 (40.0%) showed residual disease after a median of 1 regimen (IQR 1-2). Five-year overall survival in CD30 positive and negative cases was 37.0% (95% CI 22.1-61.8) and 50.1% (95% CI 27.9-90.0, p = 0.078), while after first line treatment it was 23.2% (95% CI 8.6-62.5) and 47.6% (95% CI 18.8-100, p = 0.025), respectively. On multivariable analysis CD30 positivity was a significant prognostic factor for progression-free survival (HR 2.32, 95% CI 1.04-5.19) and overall survival (HR 2.77, 95% CI 1.05-7.29). Conclusions: CD30 was retained even after an intensive pretreatment load, confirming that it is a reliable treatment target. Its expression was associated with a significantly poorer prognosis in multiple relapse/chemoresistant cases and it was an independent prognostic factor for survival.