Background: We already described the polymorphisms in resistance of PI and Rt-mutation in B and non-B HIV-1 subtypes among a cohort of highly experienced patients failing HAART.  Despite similar prior ART, there were different patterns in primary and mostly secondary RT and PI resistance mutations. It is unknown whether these differences have clinical implications.  The objective of this study was to assess the virological response of a genotypically driven salvage therapy according to HIV-1 subtype.

Methods: In patients failing HAART PI, RT sequence analysis performed by HIV-Seq and confirmed by phylogenetic analysis (PHYLIP). For each patient, salvage therapy was discussed according to prior treatment history and genetopic resistance results. Retrogram 1.4 was used for genotypic resistance mutations on PI and RT genes. An intent-to-treat analysis was performed (with missing value = failure) to evaluate the virological response according to HIV-1 clades. Response to HAART was defined as VL, < 400 and < 50 copies/mL at 6 months.

Results: 121 patients with a median baseline VL of 12,900 copies/mL (50-850,000) and 290 CD4/mL³(1-1042) were prospectively evaluated. 64 had B clades and 57 non-B clades. Mean age was 40 years (22-71). There were 79 males, and 35 patients were of African origin. Virologic response was:

 

	<400	<50
Clade B	54.5%	47.4%
Clade non-B	45.54%	52.6%

 

Follow-up data at week 48 and subanalyses comparing clades A and C will be presented.

Conclusions: This study suggests that virological response to therapy is similar in patients carrying B and non-B clades.