title: Hydrocarbon double-stapling remedies the proteolytic instability of a lengthy peptide therapeutic.
abstract: The pharmacologic utility of lengthy peptides can be hindered by loss of bioactive structure and rapid proteolysis, which limits bioavailability. For example, enfuvirtide (Fuzeon, T20, DP178), a 36-amino acid peptide that inhibits human immunodeficiency virus type 1 (HIV-1) infection by effectively targeting the viral fusion apparatus, has been relegated to a salvage treatment option mostly due to poor in vivo stability and lack of oral bioavailability. To overcome the proteolytic shortcomings of long peptides as therapeutics, we examined the biophysical, biological, and pharmacologic impact of inserting all-hydrocarbon staples into an HIV-1 fusion inhibitor. We find that peptide double-stapling confers striking protease resistance that translates into markedly improved pharmacokinetic properties, including oral absorption. We determined that the hydrocarbon staples create a proteolytic shield by combining reinforcement of overall alpha-helical structure, which slows the kinetics of proteolysis, with complete blockade of peptide cleavage at constrained sites in the immediate vicinity of the staple. Importantly, double-stapling also optimizes the antiviral activity of HIV-1 fusion peptides and the antiproteolytic feature extends to other therapeutic peptide templates, such as the diabetes drug exenatide (Byetta). Thus, hydrocarbon double-stapling may unlock the therapeutic potential of natural bioactive polypeptides by transforming them into structurally fortified agents with enhanced bioavailability.
authors.affiliation: Department of Pediatric Oncology, Dana-Farber Cancer Institute and Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Bird
authors.forename: Navid
authors.initials: N
authors.lastname: Madani
authors.forename: Alisa F
authors.initials: AF
authors.lastname: Perry
authors.forename: Amy M
authors.initials: AM
authors.lastname: Princiotto
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Supko
authors.forename: Xiaoying
authors.initials: X
authors.lastname: He
authors.forename: Evripidis
authors.initials: E
authors.lastname: Gavathiotis
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Sodroski
authors.forename: Loren D
authors.initials: LD
authors.lastname: Walensky
mesh_terms: D019380:Anti-HIV Agents / Q000737:chemistry*; D001682:Biological Availability; D023581:HIV Fusion Inhibitors / Q000737:chemistry* / Q000493:pharmacokinetics; D015658:HIV Infections / Q000188:drug therapy / Q000517:prevention & control; D006801:Humans; D006838:Hydrocarbons / Q000737:chemistry* / Q000627:therapeutic use; D010455:Peptides / Q000493:pharmacokinetics* / Q000627:therapeutic use; D013329:Structure-Activity Relationship
chemical_list: D019380:Anti-HIV Agents; D023581:HIV Fusion Inhibitors; D006838:Hydrocarbons; D010455:Peptides