SMART - study on mutations and antiretroviral therapy: preliminary results

SMART has been designed to study resistance among naive, responder and non responder patients to 2 NRTIs. Responders were subjects with undetectable V L, or a reduction > 2 Log, after greater than or equal to 6 months of thera py. Treatment failure was defined by the detection of > 0.5 Log increase in VL after > 6 months of therapy. Mutations were evaluated by direct sequenc ing of the RT or by LiPA, only in patients with detectable viremia. Resista nce to NRTIs is low among naive individuals. In non responders subjects the re is an high rate of resistance to AZT and 3TC and a low rate of resistanc e to ddI and d4T; this might explain the majority of treatment failures. Re sistance to AZT and 3TC is high also in responders patients: at the moment, our data are inadequate to evaluate whether this could impair future thera pies or accelerate treatment failure. Resistance to d4T and ddI is low even among non responders patients.