title: Pharmacokinetics and in vitro and in vivo anti-tumor response of an interleukin-2-human serum albumin fusion protein in mice.
abstract: OBJECTIVE
  Albuleukin fusion protein is a recombinant human interleukin-2 (rIL-2) genetically fused to recombinant human serum albumin (rHSA). The pharmacokinetics and pharmacologic activity of Albuleukin were examined in mice to determine whether the fusion protein had the immunomodulatory and anti-tumor properties of rIL-2 as well as a prolonged serum half-life due to the rHSA.
  
  
  METHODS
  The effect of Albuleukin on lymphocyte proliferation, IL-2 receptor binding, and release of IFN-gamma from human NK cells were examined in vitro. For the pharmacokinetic analysis, Albuleukin and rIL-2 were administered intravenously (i.v.) and subcutaneously (s.c.) to BALB/c mice, both at a single dose of 500 microg/kg. The anti-tumor properties of Albuleukin were evaluated in a Renca tumor model in BALB/c mice and in a metastatic liver model of B16F10 melanoma in C57B1/6 mice. In the Renca tumor model, BALB/c mice were dosed intraperitoneally (i.p.) and s.c. with Albuleukin on days 12, 14, 16, 19, 21, and 23 and i.p. with rIL-2 daily for two periods of 5 days (days 10-14 and 17-21). In the B16 melanoma model, C57B1/6 mice were dosed s.c. with rIL-2 twice daily or Albuleukin every 48 h for 14 days.
  
  
  RESULTS
  In vitro, Albuleukin induced the proliferation of primary human and mouse T cells and B cells and primary human NK cells, competed with rIL-2 for binding to the IL-2 receptors, and induced the production of IFN-gamma from primary human NK cells. The s.c. bioavailability of Albuleukin was about 45% relative to the i.v. dose. Plasma half-life was prolonged and ranged from 6 to 8 h with Albuleukin, compared to 19-57 min with rIL-2. Total clearance of Albuleukin was about 50-fold slower than that of rIL-2 after i.v. dosing. In vivo, Albuleukin suppressed the growth of Renca tumors and induced a dense infiltration of CD4+ and CD8+ T cells. Both Albuleukin and rIL-2 significantly reduced the tumor burden in mice with hepatic B16F10 metastases. Albuleukin significantly reduced the incidence of residual macroscopic hepatic tumors, resulting in improved survival relative to controls and rIL-2.
  
  
  CONCLUSIONS
  Results from these studies suggest that the therapeutic efficacy of rIL-2 is improved in mice by prolonging its in vivo half-life through genetic fusion to albumin. Albuleukin, the fusion protein, had pronounced anti-tumor effects in Renca and hepatic melanoma tumor models without an increase in mortality. On the basis of its preclinical effects, Albuleukin was brought to the clinic to assess its therapeutic benefit in a variety of cancers.
authors.affiliation: Medtronic Vascular, Santa Rosa, CA, 95403, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Melder
authors.forename: Blaire L
authors.initials: BL
authors.lastname: Osborn
authors.forename: Todd
authors.initials: T
authors.lastname: Riccobene
authors.forename: Palanisamy
authors.initials: P
authors.lastname: Kanakaraj
authors.forename: Ping
authors.initials: P
authors.lastname: Wei
authors.forename: Guoxian
authors.initials: G
authors.lastname: Chen
authors.forename: David
authors.initials: D
authors.lastname: Stolow
authors.forename: Wendy Green
authors.initials: WG
authors.lastname: Halpern
authors.forename: Thi-Sau
authors.initials: TS
authors.lastname: Migone
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Krzysztof J
authors.initials: KJ
authors.lastname: Grzegorzewski
authors.forename: Gilles
authors.initials: G
authors.lastname: Gallant
mesh_terms: D000818:Animals; D005260:Female; D006207:Half-Life; D006801:Humans; D007376:Interleukin-2 / Q000493:pharmacokinetics / Q000494:pharmacology*; D008114:Liver Neoplasms, Experimental / Q000517:prevention & control / Q000556:secondary; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D008546:Melanoma, Experimental / Q000188:drug therapy; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000188:drug therapy*; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics / Q000494:pharmacology*; D012709:Serum Albumin / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins; D012709:Serum Albumin