Methods: An observational retrospective study conducted in an inner-city HIV clinic identified 10 patients on PI monotherapy who each had 2 GenoSure Archive® (Labcorp) resistance profiles performed. Gender, race, prior cART, and baseline VL and CD4+ count were captured. VL and CD4+ count were trended in the time period between resistance tests. These profiles were then compared checking for the emergence of new primary PI mutations.
Results: Seven out of 10 patients were African American, 2 were Hispanic, 1 was Caucasian, and half were male. The mean time interval between archived resistance tests was 6.87 months. During the time between resistance profiles, 9 were on darunavir and 1 switched from lopinavir to darunavir for less pill burden. Eight had an undetectable VL (defined by <50 copies/mL) at the first resistance test, 7 had undetectable VL at the second resistance test, and 6 remained undetectable over the entire period between profiles. There were 3 that demonstrated blips in VL and 1 that experienced virological failure between the two sets of resistance tests. One patient had an initial resistance profile showing primary resistance to lopinavir. No patients gained any primary PI mutations to darunavir.
Conclusion: The results of this study suggest that mainly darunavir-based PI monotherapy has good genetic barrier, even in the setting of virological failure. Larger studies examining similar data over longer durations are needed to confirm this finding.
T. Haddad, None
B. Learned, None
J. Slim, None