Oral leukoplakia is the most common potentially malignant oral disorder. Oral leukoplakia's malignant potential is independent of the histopathological grade, and the malignant transformation rate varies greatly from 3% to 50% even in the case of severe epithelial dysplasia. Ethnic & environmental variables may contribute to this variation. C-kit immunohistochemistry was performed on 15 oral leukoplakia (OL), two oral squamous cell carcinoma (OSCC), and two dentigerous cysts (DC). The objective of this study was to evaluate the c-kit expression in oral leukoplakia. The use of various immunohistochemical markers to differentiate between OLs with a high and low risk of malignant transformation has been investigated. Only four OL exhibited a faint cytoplasmic expression in basal cells. Whereas, OSCC and DC were devoid of c-kit expression. Thus, this may not be a unique marker for identifying OL at high-risk. Further research with larger sample size is required. Key Words: CD 117, Disease progression, Oral dysplasia, Oral leukoplakia, Risk prediction.
HPV-independent head and neck squamous cell carcinoma (HNSCC) is a common cancer globally. The overall response rate to anti-PD1 checkpoint inhibitors (CPIs) in HNSCC is ~16%. One major factor influencing the effectiveness of CPI is the level of tumor infiltrating T cells (TILs). Converting TILlow tumors to TILhigh tumors is thus critical to improve clinical outcome. Here we describe a novel DNA vaccines to facilitate the T-cell infiltration and control tumor growth. We evaluated the expression of target antigens and their respective immunogenicity in HNSCC patients. The efficacy of DNA vaccines targeting two novel antigens were evaluated with or without CPI using a syngeneic model. Most HNSCC patients (43/44) co-expressed MAGED4B and FJX1 and their respective tetramer-specific T cells were in the range of 0.06-0.12%. In a preclinical model, antigen-specific T cells were induced by DNA vaccines and increased T cell infiltration into the tumor, but not MDSC or regulatory T cells. The vaccines inhibited tumor growth and improved the outcome alone and upon combination with anti-PD1 and resulted in tumor clearance in approximately 75% of mice. Pre-existence of MAGED4B and FJX1-reactive T cells in HNSCC patients suggests that these widely expressed antigens are highly immunogenic and could be further expanded by vaccination. The DNA vaccines targeting these antigens induced robust T cell responses and with the anti-PD1 antibody conferring excellent tumor control. This opens up an opportunity for combination immunotherapy that might benefit a wider population of HNSCC patients in an antigen-specific manner.