Abstract B164: A platform of metastatic bioluminescent PDX: Focus on HBCx14-Luc1 metastatic bioluminescent breast tumorgaft model for preclinical studies.
Authors: Bourre Ludovic , Bernes Mylène , Leven Enora , Yvonnet Vanessa , Déas Olivier , Lassalle Myriam , Judde Jean-Gabriel 
Published: August 2014

Background: The ability of tumor cells to spread and form metastases is one of the key parameters used to classify tumor aggressiveness. Metastasis detection at diagnosis or during followup post-surgery is associated with poor prognosis. The paucity of pertinent models to investigate the biology of metastasis renders problematic the set-up of anti-metastasis therapies. We took advantage of our human patient-derived xenograft (PDX) collection to develop models suitable to assess anti-metastatic therapy. To enable evaluation of metastasis response to treatment, we labeled tumors with lentivirus-mediated luciferase insertion, allowing longitudinal followup of metastasis formation by non-invasive imaging. A review of our metastatic bioluminescent PDX panel is described here with a particular focus on our most advanced bioluminescent breast model HBCx-14-Luc1.

Methods: Tumor cells from freshly excised PDXs were dissociated and transduced with a defective lentivirus bearing the firefly luciferase gene. One million transduced cells were injected subcutaneously into immunocompromised mice (Nude or SCID), tumor growth and metastasis formation were monitored throughout passages by whole body visualization and ex vivo organ imaging at the end point using the Xenogen IVIS® Lumina. Bioluminescence was measured every two weeks, over 8 to 20 weeks, to assess metastasis appearance and progression. The presence of metastases was confirmed by histological analysis.

Results: Lung metastases developed in a variety of PDX models (breast, prostate, pancreas, and melanoma) with different output according to the model and the mouse strain used. SCID mice were more permissive to metastasis development than nude mice. In our most advanced model, HBCx-14-Luc1, the influence of primary tumor resection was assessed on both lung metastasis apparition delay and frequency of metastasis positive mice. Regarding metastasis positive mice at the end point, no difference was observed between resected (7/8 positive at D88) and non-resected mice (11/13 at D93). However, while the first day of metastasis apparition was similar between non-resected (D48) and resected mice (D53), the number of metastasis positive mice at this early time-point was higher for the non-resected (7/8) compared to resected mice (3/18). Histological examination confirmed the adenocarcinomatous origin of metastases. Another breast PDX model, HBCx-5-Luc2, was metastatic for pancreas, brain, spleen, liver, lung, and bones as assessed by ex vivo screening. Additional PDX models were screened similarly to get a metastasis organ mapping.

Conclusions and Perspectives: Bioluminescent metastatic PDX models of various tumor histotypes were successfully established by growing luciferase-engineered PDXs subcutaneously into appropriate mouse strains. These models will provide a useful tool to explore the biology of metastasis and evaluate anti-metastatic therapies in a selection of organs.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B164.

Citation Format: Ludovic Bourre, Mylène Bernes, Enora Leven, Vanessa Yvonnet, Olivier Déas, Myriam Lassalle, Jean-Gabriel Judde. A platform of metastatic bioluminescent PDX: Focus on HBCx14-Luc1 metastatic bioluminescent breast tumorgaft model for preclinical studies. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B164.