Immunohistochemical Expression of WT1 in Nasopharyngeal Carcinoma Among Filipino Patients in a Tertiary Hospital

Background. Nasopharyngeal carcinoma (NPC) is endemic in Southeast Asia and the Philippines. Novel treatments are desirable due to the high disease burden and adverse effects of existing modalities. Detection of WT1 expression via immunohistochemistry has been reported in many tumors. Moreover, immunotherapy via WT1 peptide vaccination has shown promising results in a wide range of malignancies. No studies on WT1 expression in NPC have been published in any population. Objective. Documenting WT1 expression in NPC via immunohistochemistry may provide insight into the possibility of using WT1 vaccination for this disease. Methodology. This was a retrospective descriptive study. All newly-diagnosed cases of NPC from 2016 to 2017 with samples stored in the Department of Laboratories of the Philippine General Hospital were considered. Cases were included based on specific criteria. The tumor classification of each case was reviewed and WT1 immunohistochemistry staining was performed. Assessment of the strength of WT1 immunostaining was conducted. The results were analyzed using Chi-square test for association with fisher exact correction. Results. A total of 57 cases were included, all of which were non-keratinizing squamous cell carcinomas (NK-SCCs). Forty-nine were undifferentiated type while eight were differentiated type. The mean age was 48 years. Two thirds were male, one third were female. Seventeen of the 57 cases (29.8%) were positive for WT1 immunostaining, and all were undifferentiated type. The majority (82.32%) of the positive cases showed cytoplasmic expression. There was a significant association between tumor classification and WT1 staining. Conclusion. Similar to studies conducted in other carcinomas, a considerable subset of NPCs express WT1. This finding opens other avenues for exploration, including the feasibility of WT1 peptide vaccination as a treatment option. Further studies on the associations between WT1 and NPC are recommended.