Abstract A20: Development and pharmacological assessment of new models of orthotopic primary human uveal melanoma and retinoblastoma xenografts.

Abstract

Background: The treatment of both uveal melanoma and retinoblastoma could require enucleation in unfavorable prognostic disease. In order to allow pharmacological assessment of innovative intraocular treatments in more relevant and predictive models, we have developed preclinical orthotopic xenografts of both primary human uveal melanoma (UM) and retinoblastoma (Rb) into immunodeficient mice. Materials and methods: Orthotopic models of human UM and Rb have been developed from two panels of subcutaneous xenografts previously established and characterized in the laboratory (Némati et al 2010; Aerts et al 2010), i.e. 6 UM models (MP34, MP41, MP42, MP55, MP65, and MM26) and 3 Rb models (RB102, RB111, and RB200). Mice bearing xenografts were sacrificed and tumors were dissected to obtain a suspension of fresh tumor cells at a concentration of 8000 cells/l in DMEM serum-free medium. Under intraperitoneal anesthesia, 2 l of cell suspension was injected into the subretinal space of the right eye for 3 groups of mice using a 32G needle via a Hamilton syringe. Each group was constituted by 3 to 6 SCID mice. After sub-retinal injection, ophthalmic examination of the mice was performed weekly. When tumor cells invaded vitreal cavity and anterior chamber, the mice were sacrificed for ophthalmological pathological analyzes. Finally, using the RB200 model, we have then evaluated the efficacy of 2 μl intraocular administration of bevacizumab (25 mg/kg/week for 4 weeks), melphalan (500 μg/kg/week for 4 weeks), and carboplatin (100 μg/kg/week for 4 weeks). Results: The 6 UM cells developed in all injected eyes, 6 to 10 weeks after orthotopic transplantation. Pathological analyzes confirmed UM diagnosis and conservation of histological sub-type, i.e. epithelioid and/or spindle cell, than in corresponding patient's tumors and subcutaneous xenografts. Liver tissues examination is on-going. Rb tumor cells developed in all injected eyes 4 to 6 weeks after orthotopic transplantation for RB102 and RB200. In contrast, no tumor growth was observed in injected eyes of the RB111 model. Pathological examination of the injected eyes confirmed the presence of a massive infiltration of the retina, vitreous and anterior chamber by retinoblastoma cells. Finally, we have observed a high efficacy of intraocular administration of carboplatin (17% of intraocular tumors), but not bevacizumab (100%) nor melphalan (67%), in the RB200 model than in the control group. Conclusions: We have developed relevant and available preclinical models of human UM and Rb that allow pharmacological assessment of intraocular standard therapies. We will now evaluate innovative therapeutic approaches in such a tumor situation. Némati et al. Clin Cancer Res 2010;16:2352–2362. Aerts et al. Photodiagnosis Photodyn Ther 2010;7:275–283. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A20.