Abstract 1656: CXCR4 antagonist-expressing liposomes reduce lung metastases and deliver drugs to CXCR4 expressing cells: a new drug-targeting device

Abstract

Abstract Introduction. CXCR4 is overexpressed in multiple tumors regulating metastatic dissemination. A new class of cyclic peptides antagonist for CXCR4 receptors was recently developed1. To improve peptide efficacy and increase its delivery delivery to target cancer cells the most active antagonist, Pep R, was coupled to PEGylated liposomes (PL). Experimental Procedures. PL conjugated to the liposomes (Lip-PepR) were prepared starting by athiolated derivative of antiCXCR4 peptides coupled to the pre-formed PL. Doxorubicin (DOX) was then encapsulated by remote loading method. Lip-PepR was evaluated through migration assay in A498 human renal cancer cell line in vitro and in an experimental animal model of pulmonary metastasis development in vivo (C57/BL mice injected with B16-CXCR4 cells and treated with 0.1 mg/kg Lipo-PepR and lipo-unconjucated i.v. twice a week for two weeks). DOX-encapsulating Lipo-PepR was evaluated in CXCR4 positive cells A498 and HT29 (human renal and colon cancer cell lines, respectivally) versus negative CXCR4 expressing cells FB-1(human anaplastic thyroid cell line), as mean cellular fluorescence. Finally, the cytotoxic effect of the lipo-DOX-PepR was examined, in A498, and HT29 cells. Results. To evaluate the antagonistic CXCR4 function of Lipo-PepR, migration assays were conducted in A498, CXCR4 expressing cells. A498 cells were treated with the PepR or with liposome preparation (Lipo-PepR) and induced to migrate toward the CXCR4 ligand CXCL12. PepR alone inhibited cell migration such as the CXCR4 antagonist, AMD3100 while the functionalized peptide, Lipo-PepR (10µM) more efficiently inhibited migration CXCL12-induced compared. To validate the Lipo-PepR efficacy in vivo, metastases development assays were conducted. C57/BL mice were injected with murine B16-hCXCR4 melanoma cells and treated twice a week iv with Lipo-PepR versus Peptide R alone. A significant reduction in lung metastases was detected in mice treated with Lipo-Pep R even with lower dose of the Lipo-PepR (0.1mg/kg) compared to the usually used (2mg/kg). Moreover, to allow a target selective drug delivery, Lipo-PepR liposomes were loaded with doxorubicin (DOX). A CXCR4 dependent higher DOX accumulation was registered in CXCR4 positive cells, A498 and HT29 resulting in a specific higher cytotoxicity. Conclusions. Liposomes conjugated- rationally designed CXCR4 antagonist were more efficient in inhibiting CXCR4 in vitro and in vivo. Moreover Lip-PepR loaded with a chemotherapeutic drug, such as DOX, demonstrated an enhanced drug accumulation into CXCR4 overexpressing cells. 1. Portella L et al. PLoS One. 2013 Sep 13;8(9):e74548 Citation Format: Caterina Ierano, Sara Lusa, Crescenzo D'Alterio, Giuseppina Salzano, Maria Napolitano, Maria Buoncervello, Massimo Spada, Daniele Macchia, Antonio Barbieri, Antonio Luciano, Lucia Gabriele, Giuseppe De Rosa, Stefania Scala. CXCR4 antagonist-expressing liposomes reduce lung metastases and deliver drugs to CXCR4 expressing cells: a new drug-targeting device. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1656. doi:10.1158/1538-7445.AM2014-1656