The protease inhibitor fosamprenavir [Lexiva, Telzir] is well tolerated and produces sustained virological responses, even in patients with advanced disease, according to the results of studies presented at the XV International AIDS Conference [Bangkok, Thailand; July 2004]. In an ongoing extension of the SOLO and NEAT studies (APV30005), fosamprenavir was found to have sustained efficacy after 96 weeks' treatment, with no new adverse events and limited resistance mutations. Furthermore, switching from amprenavir to fosamprenavir was also well tolerated and associated with sustained virological suppression.