ancestim ancestim ancestim is a recombinant methionyl human stem cell factor, branded by amgen as stemgen. it was developed by amgen and sold to biovitrium, now swedish orphan biovitrum, in december, 2008. ancestimclinical dataahfs/drugs.cominternational drug namesroutes ofadministrations.c. injection only, premedication with h1 and h2 antihistamines and beta-receptor agonists for bronchodilationatc codel03aa12 (who) pharmacokinetic dataelimination half-life2.5 hexcretionrenal: 90%identifierscas number163545-26-4 nchemspidernoneuniipyb4q6jg41keggd02937 y ny (what is this?) (verify) it is a 166 amino acid protein produced by e. coli bacteria into which a gene has been inserted for soluble human stem cell factor. it has a monomeric molecular weight of approximately 18,500 daltons and normally exists as a noncovalently associated dimer. the protein has an amino acid sequence that is identical to the natural sequence predicted from human dna sequence analysis, except for the addition of an n-terminal methionine retained after expression in e. coli. because ancestim is produced in e. coli, it is nonglycosylated. ancestim is supplied as a sterile, white, preservative-free, lyophilised powder for reconstitution and administration as a subcutaneous (sc) injection and is indicated for use in combination with filgrastim for mobilizing peripheral hematopoietic stem cells for later transplantation in certain cancer patients.