title: Emerging patterns and implications of HIV-1 integrase inhibitor resistance.
abstract: OBJECTIVE
  This review highlights recent data on the pathways of resistance that impact the clinical activity of first-generation and second-generation integrase inhibitors.
  
  
  RESULTS
  Raltegravir (RAL) and elvitegravir (EVG) are highly efficacious in first-line antiretroviral therapy, with small numbers of virological failures observed in clinical trials. Durable activity in treatment-experienced patients requires a fully supportive background regimen. RAL and EVG show a low-to-moderate genetic barrier to resistance and extensive cross-resistance, which preclude their sequential use. Resistance to dolutegravir (DTG) is not selected as readily in vitro and has not emerged in studies of treatment-naïve patients to date. Both in vitro and in vivo, DTG retains activity against several RAL and EVG resistant strains, but susceptibility is variably impaired by multiple mutations within the G148 pathway, which are common after RAL or EVG failure. Cross-resistance can be partially overcome by doubling DTG dosing to twice daily, but durability of responses remains dependent on a supportive background regimen. There is variability in the integrase gene of circulating HIV strains, which does not appear to reduce drug activity, although it may influence the emergence and evolution of integrase resistance. Transmission of integrase resistance remains rare but surveillance is required.
  
  
  CONCLUSIONS
  Integrase inhibitors provide a potent option for the treatment of HIV infection. Drug resistance remains a challenge, which may be partially overcome by the introduction of second-generation compounds. Prompt management of RAL and EVG failure is required to prevent the accumulation of multiple resistance mutations that reduce DTG susceptibility.
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Liverpool, UK. geretti@liverpool.ac.uk
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Geretti
authors.forename: Daniele
authors.initials: D
authors.lastname: Armenia
authors.forename: Francesca
authors.initials: F
authors.lastname: Ceccherini-Silberstein
mesh_terms: D024882:Drug Resistance, Viral; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology*; D019427:HIV Integrase / Q000235:genetics / Q000378:metabolism*; D019428:HIV Integrase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans
chemical_list: D019428:HIV Integrase Inhibitors; D019427:HIV Integrase; C514801:p31 integrase protein, Human immunodeficiency virus 1