Riporto qui per conoscenza il testo dell’abstract che verrà presentato all’American Association for Cancer Research (AACR) il 3 aprile e dal titolo “The novel direct-acting vascular targeting agent NGR-TNF exerts in vivo antitumor activity by inducing endothelial and tumor cell death in the absence of proangiogenic bone-marrow derived cell recruitment”.
Per chi fosse interessato al meeting, i corpi del testo dei late breaker saranno resi noti il 30 marzo.
Presentation Time: Tuesday, Apr 03, 2012, 1:00 PM – 5:00 PM
Author Block: Paola Di Matteo1, Christina Hackl2, Christopher Jedeszko2, Simona Porcellini1, Barbara Valentinis1, Claudio Bordignon1, Catia Traversari1, Robert S. Kerbel2, Gian-Paolo Rizzardi1. 1Molmed S.p.A., Milano, Italy; 2Sunnybrook Health Sciences Centre, Molecular and Cellular Biology Research, and Department of Medical Biophysics, University of Toronto, Torondo, ON, Canada
Abstract Body: Treatment with either certain chemotherapy drugs at maximum tolerated dose (e.g. paclitaxel, cyclophosphamide, 5-FU), vascular-disrupting agents (VDAs; e.g. fosbretabulin, Oxi4503), or local irradiation can rapidly induce mobilization and subsequent tumor homing of proangiogenic bone marrow derived cells (BMDCs), such as circulating endothelial progenitor cells (CEPs), CD11b/Tie-2-expressing monocytes (TEMs), CD11b+Gr1+ neutrophils and myeloid-derived suppressor cells (MDSCs). Increase in several growth factors and chemokines, such as SDF-1, G-CSF as well as osteopontin, contribute to the mobilization of these BMDCs that can colonize the drug treated tumors preferentially at the viable tumor rim that characteristically remains after treatment with drugs such as VDAs. This process promotes angiogenesis and rapid tumor regrowth, thus diminishing the overall antitumor activities of the aforementioned treatments. NGR-TNF, presently in advanced clinical development, is a direct-acting vascular targeting agent coupling the CNGRCG peptide (NGR), homing to angiogenic blood vessels, and tumor necrosis factor alpha (TNF). Experiments performed in the Lewis lung carcinoma (LLC) model, suggested that when administrated at low doses, NGR-TNF causes a decrease of tumor blood vessels density and induces apoptosis of tumor cells without inducing cytokine-rebound and recruitment of pro-angiogenic BMDC. In order to extend these results, we investigated whether NGR-TNF fails to mobilize proangiogenic BMDC even after repeated treatments and in a highly aggressive and metastatic tumor model. LLC and 4T1 mammary gland carcinoma cells were subcutaneously implanted respectively into immunocompetent C57BL/6J or Balb/C mice. Blood was obtained by cardiac puncture or retro-orbital sinus bleeding, 4, 24 hours or 1 week after single or repeated treatments with either NGR-TNF at low and high dose or saline. Using flow cytometry CEPs were defined as CD45-/CD13+/flk-1+/CD117+/7AAD-, TEMs as CD45+/CD11b+/Tie2+ and MDSCs as CD45+/CD11b+/Gr1+ cells. At low doses, NGR-TNF exerts a control of 4T1 primary tumor growth, without inducing cytokine rebound and pro-angiogenic BMDCs mobilization. In addition, even after repeated administrations at low doses, NGR-TNF fails to mobilize or recruit to the tumor site different subtypes of BMDCs. Therefore, low doses of NGR-TNF exert an antitumor activity without inducing a reactive pro-angiogenic host response, and as such provide an explanation and the rationale for the successful use of lower dose NGR-TNF administration protocols in the clinic.