Ligand-Mediated Selective Targeting of Adenovirus in Metastatic Breast Cancer – Bispecific Adaptor for Breast Cancer Virotherapy

Ligand-Mediated Selective Targeting of Adenovirus in Metastatic Breast Cancer

Introduction: The success of gene therapy relies on efficient and targeted delivery systems. Adenovirus vectors have a number of advantages for gene therapy. However, one main problem is their lack of tumor tropism. Many solid tumors and hematopoietic tumors over express the chemokine receptor CXCR4. Recent evidence has highlighted the role of CXCR4 in cancer, particularly in cancer metastasis. The present study addresses this issue by retargeting adenovirus to the breast cancer cells overexpressing CXCR4 receptor. We used sCAR-T4-CXCL12, a bispecific adaptor molecule with the ectodomain of CAR linked by the T4 fibritin trimerization motif to the human CXCR4 ligand CXCL12. We hypothesize sCAR-T4-SDF–1α would retarget adenovirus vectors to CXCR4-positive breast cancer metastases.

Material and Methods: Infectivity assays in the absence as well as presence of ligand were performed in human breast cancer MDA-MB–435 cells. Cells were infected with different titres of Ad-CMV-GFP-Luc with and without ligand. Cells were harvested and analysed for the GFP expression by fluorescent microscopy and flow cytometry.

Results: Quantification by flow cytometry demonstrated a dramatic 20- to 40-fold increase in the infectivity of cells both in a dose-dependent and time-dependent manner using the sCAR-T4-SDF–1α targeted adenovirus compared to the untargeted vector.

Conclusions: We showed that sCAR-T4-SDF–1α can significantly redirect an adenoviral gene therapy vector to breast cancer cells in culture. This bispecific ligand should, therefore, be a powerful agent to retarget adenovirus vectors to tumor metastases.

Bispecific Adaptor - Breast Cancer - CXCR4 - Transductional Targeting - Virotherapy