Dear Ziad,
Several studies have showed that Neupogen and similar drugs don't increase the risk for leukemia or increased blast cells:
http://www.ncbi.nlm.nih.gov/pubmed/21900223
I have been taking Neupogen mostly 2 injections/week from Sept 2007 to Nov 2011 without increased blast cells in blood or bone marrow. For the moment I don't need Neupogen since I have responded well to Thalidomide.
Kind regards
Birgitta-A