MOUSE SUPRACHOROIDAL ORTHOTOPIC MODEL FOR SPONTANEOUS METASTASIS OF UVEAL MELANOMA

Abstract

Purpose : Uveal melanoma (UM) is the most common intraocular malignancy in adults.
Currently, there is any effective therapeutic option for patients with metastatic disease since the UM is resistant to conventional chemotherapy and immune checkpoint blockade, showing poor response rates and limited overall survival.
Recent advances in the identification of early driver mutations and aberrant signaling pathways that contribute to the progression of UM, open new therapeutic strategies against specific targets.
To develop a mice xenograft model that mimics the metastatic process and that could to be used in pre-clinical studies to analyze the efficacy of new drugs or inhibitors that might interfere the growth of liver metastases.

Methods : We developed a xenograft model of human uveal melanoma in NSG (NOD-scidIL2Rgnull) strain mice that have severe immunodeficiency. UM cells have been orthotopically implanted in the suprachoroidal space by surgery of previously anesthetized mice. We had incorporated the luc2 gene into the cells and the bioluminescence signal in vivo was detected with the IVIS-LUMINA XR imaging system to follow the development of metastasis. Immunohistochemical studies were performed to verify the melanocytic origin.
Tissue samples were collected, paraffined, and immunohistochemical studies were performed to verify the melanocytic origin and cellular and molecular characteristics of the primary tumor and metastatic lesions developed in the mice.

Results : Our results show that 100% of mice injected with either 2x10⁵ OMM2.5 cells (n = 23) or MP # 41 cells (n = 24) have developed a primary tumor, which was detected at 10 ± 2 days after implantation. Enucleation of primary tumors was performed in all cases 16 ± 2 days after implantation. The bioluminiscence signal was detected at 23 ± 2 days and in liver at 31 ± 9 days after implantation of UM cells. Lung metastases were confirmed in 100% of the animals at necropsy (sacrifice per day 45 ± 11). Liver metastases were found in 87% of the animals that received OMM 2.5 cells and in 100% of those implanted with MP # 41. We also observed the presence of kidney metastases in 19% of mice on both lines. In contrast, only MP# 41 cells generated lymph node metastases.

Conclusions : We have successfully developed an in vivo mice metastatic model that allows to follow up the whole process of metastasis formation where new therapeutic strategies can be studied.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.