The enhanced in vitro hematopoietic activity of leridistim, a chimeric dual G-CSF and IL-3 receptor agonist

Abstract

The in vitro activity of leridistim was characterized for cell proliferation, generation of colony-forming units (CFU) and differentiation of CD34 + cells. In AML-193.1.3 cells, leridistim exhibited a significant increase in potency compared to rhG-CSF, SC-65303 (an IL-3 receptor agonist) or an equimolar combination of rhG-CSF and SC-65303. CFU-GM assays demonstrated that at 50% of the maximum response, the relative potency of leridistim was 12-fold greater than the combination of rhG-CSF and rhIL-3 and 44-fold more potent than rhG-CSF alone. In multi-lineage CFU assays, a combination of erythropoietin (rhEPO) and leridistim resulted in greater numbers of BFU-E, CFU-GEMM and CFU-Mk than rhEPO alone. Ex vivo culture of peripheral blood or bone marrow CD34 + cells with leridistim substantially increased total viable cells over cultures stimulated with rhG-CSF, SC-65303, or a combination of rhG-CSF and SC-65303. Culture with leridistim, resulted in a greater increase in myeloid (CD15 + /CD11b + ), monocytic (CD41 − /CD14 + ) and megakaryocytic (CD41 + /CD14 − ) precursor cells without depleting the progenitor pool (CD34 + /CD15 − /CD11b − ). These results demonstrate that leridistim is a more potent stimulator of hematopoietic proliferation and differentiation than the single receptor agonists (rhG-CSF and SC-65303) either alone or combined. These unique attributes suggest that leridistim may enhance hematopoietic reconstitution following myelosuppressive chemotherapy.

Signal transduction mediated by the Ras/Raf/MEK/ERK pathway from cytokine receptors to transcription factors: potential targeting for therapeutic intervention

“…[4][5][6][7][8] Among the various signaling pathways triggered by hematopoietic factors is the Ras/Raf/ MEK/ERK pathway, which has been shown by us as well as others to play important roles in cell proliferation and the prevention of apoptosis. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] An overview of the Ras/Raf/MEK/ ERK cascade is presented in Figure 1. Many of the members of this pathway, including Ras, Raf, and their downstream transcription factor targets NF-kB, AP-1, c-Myc and Ets-1 were initially identified as proto-oncogenes.…”

The Raf/MEK/ERK signal transduction cascade as a target for chemotherapeutic intervention in leukemia

“…101,102 Furthermore, chimeras between G-CSF and FLT-3 ligand have also been developed and show potential for preventing apoptosis in certain cells, as well as dendritic cells. 103,104 These types of studies should provide much needed insight into post-chemotherapeutic care in leukemia patients.…”

Requirement for the PI3K/Akt pathway in MEK1-mediated growth and prevention of apoptosis: identification of an Achilles heel in leukemia

“…[1][2][3][4][5][6] Hematopoietic cell lines have been isolated which require IL-3 or in some cases GM-CSF for survival and cell proliferation. 7 The murine FDC-P1 cell line is an IL-3/GM-CSFdependent cell line isolated from the bone marrow of a DBA/2 mouse.…”