Study 903 Introduction
Tenofovir disoproxil fumarate (tenofovir DF, TDF) is a nucleotide analogue that has been recently approved in the U.S. and E.U. for the treatment of HIV-1 infection
In vitro, tenofovir can select for the K65R mutation in HIV-1 RT which results in reduced susceptibility to tenofovir and some other NRTIs (see Results)
The K65R mutation also results in reduced enzymatic efficiency (decreased Kpol and Km) as well as reduced viral fitness (Selmi et al, 2001; White et al, 2002)
Clinical studies in treatment-experienced patients have shown that the K65R mutation occurs in approximately 3% of patients after up to 96 weeks of tenofovir DF therapy
- no increase in development of K65R over time
- development of K65R was not associated with HIV RNA rebound
- no evidence for development of other types of resistance mutations to tenofovir DF
The current study analyzes the development of resistance in treatment-naïve patients undergoing tenofovir DF therapy in combination with lamivudine (3TC) and efavirenz (EFV)