Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is common in Southern China and South-East Asia. Immune checkpoint blockade (ICB) is being studied in NPC and initial monotherapy ICB studies show early promise. Currently, lack of representative NPC models limit the preclinical studies to evaluate the efficacy and safety of novel ICB and combination regimens. Hence, there is a need to develop and characterize a mouse model with human immune system for testing immunotherapy. Here, we engrafted NPC-PDX in immunodeficient NSG mice, with a successful growth rate of 16.7% (6 out of 36), and humanized mouse NPC-PDX model was established subsequently. Of note, EBV latent membrane protein-1 was retained in the NPC in both NSG and humanized mice as revealed by IHC staining. There was an increase in tumor-infiltrating CD4+ T cells and a decrease in CD8+ cytotoxic T cells in humanized mice, when compared to the immune cells profile in circulation. Intriguingly, the expression levels of various exhaustion markers, namely PD-1, CTLA4 and TIM-3 were upregulated, particularly in the tumor-infiltrating T cells. Therefore, the use of ICB, either alone or in combination, may restore the function of anti-tumor immune effector cells. Taken together, we have established a humanized mouse NPC-PDX model, which plausibly provides a robust platform to test for the efficacy and safety of ICB and combination therapy regimens.

Citation Format: Wai Nam LIU, Shin Yie FONG, Wilson Wei Sheng TAN, Sue Yee TAN, Min LIU, Narayanan Gopalakrishna IYER, Darren Wan-Teck LIM, Qingfeng CHEN. Establishment and characterization of humanized mouse NPC-PDX model for testing immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5060.