Abstract 394: Rapid and persistant neutrophil mobilization by novel CXCR4 peptide antagonists
Authors: Portella Luigi , Napolitano Maria , Riccio Anna , D'Alterio Crescenzo , Polimeno Marianeve , Calemma Rosa , Antignani Elena , Trotta Annamaria , Barbieri Antonio , Gala Marianna , Luciano Antonio , Marcacci Gianpaolo , Amodeo Pietro , Vitale Rosa Maria , De Luca Stefania , Arra Claudio , Castello Giuseppe , Scala Stefania 
Published: August 2014

Introduction: The CXCR4 inhibitor AMD3100 is FDA-approved to provide stem cell mobilization for autologous transplantation in NHL and Multiple Myeloma patients. Newly designed CXCR4 inhibitory molecules, named Hys-7 inv, Phe-7 inv and Hys-OH, were recently discovered and validated in in vitro and in vivo studies (patent MI2010A-000093). Aim of the study was to evaluate the role of new CXCR4 inhibitors in hematopoietic stem cell and neutrophil mobilization.

Experimental procedures: 60 DBA/2 female were injected subcutaneously with 5 or 30 mg/kg of CXCR4 antagonist in comparison with AMD3100 (3 or 20 mg/kg). Blood was collected at 1, 2, 6 and 24 hours from the treatment. Neutrophilis were evaluated trough flow cytometry (Ly-6G+ cells) and colony forming unit assay (CFU) of the mobilized stem cell were performed. Bone marrow was also evaluated through flow cytometry and cytological analysis.

Results: Hys-7 inv, Phe-7 inv and Hys-OH, cyclic peptides CXCR4 antagonists, induced potent stem cell and neutrophils mobilization compared with AMD3100. Treatment resulted in a rapid and dose related increment in neutrophils count as well as hematopoietic stem and progenitor cells increase in peripheral blood (2 to 5 fold increase). Although Hys-7inv and Hys-OH induced neutrophils increment similar to AMD3100 the kinetic was different. AMD3100 (20 mg/kg) mobilized Ly-6G cells within 1 hour but transiently (no increase at 24 hours); instead Hys-7inv and Hys-OH mobilized Ly-6G within 2 hours lasting up to 24 hours. Interestingly, Phe-7 inv increased neutrophils mobilization within 1 hour lasting up to 24 hours. AMD3100 treated bone marrow showed an increase in progenitor cells myelo-committed (from 1.5 to 3 fold increase) and polimorphonuclear cells (PMN) (1.5 to 2.5 fold increase) and a reduction in mature-lymphocyte (0.4 to 0.28 fold increase); CXCR4 inhibitor peptides increased the immature myelo-committed progenitor cells (from 2 to 3 fold increase VS control) compared with AMD3100 (1.5 fold increase VS control) reducing PMN (1.5 to 1.65 fold increase) compared to AMD3100 (2.5 fold increase).

CFU showed increased colonies in peripheral blood from mice treated with cyclic-peptides (from 2.5 to 4 fold increase) compared to AMD3100 (3.5 fold increase); the highest number of CFU was reached earlier in mice treated with Hys-7inv, Phe-7 inv and Hys-OH rapidly (within 1h) versus AMD3100 (6 hours).

Conclusions: In vivo studies demonstrated that three newly synthesized CXCR4 inhibitors increased neutrophil and hematopoietic stem cells release from the bone marrow with different kinetic and duration compared to the FDA approved stem cell mobilizer AMD3100. Ongoing experiments are evaluating advantages in mobilizing precursors cells with CXCR4 cyclic-peptides antagonists compared to AMD3100.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 394. doi:10.1158/1538-7445.AM2011-394