bkt140 and Disease-Models--Animal

CXCR4 plays an important role in the retention of stem cells within the bone marrow. BKT140 (4F-benzoyl-TN14003) is a 14-residue bio stable synthetic peptide, which binds CXCR4 with a greater affinity compared with plerixafor (4 vs. 84 nmol/L). Studies in mice demonstrated the efficient and superior mobilization and transplantation of stem cells collected with GCSF-BKT140, compared with those obtained when using stem cells obtained with each one of these mobilizing agent alone. These results have served as a platform for the present clinical phase I study.. Eighteen patients with multiple myeloma who were preparing for their first autologous stem cell transplantation were included. Patients received a standard multiple myeloma mobilization regimen, consisting of 3 to 4 g/m(2) cyclophosphamide (day 0), followed by granulocyte colony-stimulating factor (G-CSF) at 5 μg/kg/d starting on day 5 and administered between 8 and 10 pm until the end of stem cell collection. A single injection of BKT140 (0.006, 0.03, 0.1, 0.3, and 0.9 mg/kg) was administered subcutaneously on day 10 in the early morning, followed by G-CSF 12 hours later.. BKT140 was well tolerated at all concentrations, and none of the patients developed grade 3 and 4 toxicity. A single administration of BKT140 at the highest dose, 0.9 mg/kg, resulted in a robust mobilization and collection of CD34(+) cells (20.6 ± 6.9 × 10(6)/kg), which were obtained through a single apheresis. All transplanted patients received ∼5.3 × 10(6) CD34(+) cells/kg, which rapidly engrafted (n = 17). The median time to neutrophil and platelet recovery was 12 and 14 days, respectively, at the highest dose (0.9 mg/kg).. When combined with G-CSF, BKT140 is a safe and efficient stem cell mobilizer that enabled the collection of a high number of CD34(+) cells in 1 and 2 aphaeresis procedures, resulting in successful engraftment.

Topics: Adult; Animals; Antineoplastic Agents; Blood Cell Count; Cell Line, Tumor; Disease Models, Animal; Drug Synergism; Female; Granulocyte Colony-Stimulating Factor; Hematopoietic Stem Cell Mobilization; Hematopoietic Stem Cell Transplantation; Hematopoietic Stem Cells; Humans; Male; Mice; Middle Aged; Multiple Myeloma; Oligopeptides; Protein Binding; Receptors, CXCR4; Treatment Outcome

Functional role of CXCR4 in chronic myelogenous leukemia (CML) progression was evaluated. Elevated CXCR4 significantly increased the in vitro survival and proliferation in response to CXCL12. CXCR4 stimulation resulted in activation of extracellular signal-regulated kinase (Erk)-1/2, Akt, S6K, STAT3, and STAT5 prosurvival signaling pathways. In accordance, we found that in vitro treatment with CXCR4 antagonist BKT140 directly inhibited the cell growth and induced cell death of CML cells. Combination of BKT140 with suboptimal concentrations of imatinib significantly increased the anti-CML effect. BKT140 induced apoptotic cell death, decreasing the levels of HSP70 and HSP90 chaperones and antiapoptotic proteins BCL-2 and BCL-XL, subsequently promoting the release of mitochondrial factors cytochrome c and SMAC/Diablo. Bone marrow (BM) stromal cells (BMSC) markedly increased the proliferation of CML cells and protected them from imatinib-induced apoptosis. Furthermore, BMSCs elevated proto-oncogene BCL6 expression in the CML cells in response to imatinib treatment, suggesting the possible role of BCL6 in stroma-mediated TKI resistance. BKT140 reversed the protective effect of the stroma, effectively promoted apoptosis, and decreased BCL6 levels in CML cells cocultured with BMSCs. BKT140 administration in vivo effectively reduced the growth of subcutaneous K562-produced xenografts. Moreover, the combination of BKT140 with low-dose imatinib markedly inhibited tumor growth, achieving 95% suppression. Taken together, our data indicate the importance of CXCR4/CXCL12 axis in CML growth and CML-BM stroma interaction. CXCR4 inhibition with BKT140 antagonist efficiently cooperated with imatinib in vitro and in vivo. These results provide the rational basis for CXCR4-targeted therapy in combination with TKI to override drug resistance and suppress residual disease.

Topics: Animals; Apoptosis; Benzamides; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Chemokine CXCL12; Disease Models, Animal; Drug Synergism; Gene Expression; Humans; Imatinib Mesylate; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Mice; Mitochondria; Oligopeptides; Piperazines; Proto-Oncogene Mas; Pyrimidines; Receptors, CXCR4; Signal Transduction; Stromal Cells; Tumor Burden; Tumor Stem Cell Assay; Xenograft Model Antitumor Assays