title: Clinical manufacturing of recombinant human interleukin 15. I. Production cell line development and protein expression in E. coli with stop codon optimization.
abstract: Interleukin 15 (IL-15) has shown remarkable biological properties of promoting NK- and T-cell activation and proliferation, as well as enhancing antitumor immunity of CD8(+) T cells in preclinical models. Here, we report the development of an E. coli cell line to express recombinant human Interleukin-15 (rhIL-15) for clinical manufacturing. Human IL-15 cDNA sequence was inserted into a pET28b plasmid and expressed in several E. coli BL21 strains. Through product quality comparisons among several E. coli strains, including E. coli BL21(DE3), BL21(DE3)pLysS, BLR(DE3)pLysS, and BL21-AI, E. coli BL21-AI was selected for clinical manufacturing. Expression optimization was carried out at shake flask and 20-L fermenter scales, and the product was expressed as inclusion bodies that were solubilized, refolded, and purified to yield active rhIL-15. Stop codons of the expression construct were further investigated after 15-20% of the purified rhIL-15 showed an extraneous peak corresponding to an extra tryptophan residue based on peptide mapping and mass spectrometry analysis. It was determined that the presence of an extra tryptophan was due to a stop codon wobble effect, which could be eliminated by replacing TGA (opal) stop codon with TAA (ochre). As a novel strategy, a simple method of demonstrating lack of tRNA suppressors in the production host cells was developed to validate the cells in this study. The E. coli BL21-AI cells containing the rhIL-15 coding sequence with a triplet stop codon TAATAATGA were banked for further clinical manufacturing.
authors.affiliation: Biopharmaceutical Development Program, SAIC-Frederick Inc., National Cancer Institute at Frederick, Frederick, MD 21702, USA.
authors.forename: Vinay V
authors.initials: VV
authors.lastname: Vyas
authors.forename: Dominic
authors.initials: D
authors.lastname: Esposito
authors.forename: Terry L
authors.initials: TL
authors.lastname: Sumpter
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Broadt
authors.forename: James
authors.initials: J
authors.lastname: Hartley
authors.forename: George C
authors.initials: GC
authors.lastname: Knapp
authors.forename: Wei
authors.initials: W
authors.lastname: Cheng
authors.forename: Man-Shiow
authors.initials: MS
authors.lastname: Jiang
authors.forename: John M
authors.initials: JM
authors.lastname: Roach
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Yang
authors.forename: Steven L
authors.initials: SL
authors.lastname: Giardina
authors.forename: George
authors.initials: G
authors.lastname: Mitra
authors.forename: Jason L
authors.initials: JL
authors.lastname: Yovandich
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Creekmore
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Waldmann
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zhu
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects; D018388:Codon, Terminator; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D019409:Interleukin-15 / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018388:Codon, Terminator; D019409:Interleukin-15; D011994:Recombinant Proteins