Is a lopinavir/indinavir-based therapy adequate for salvage in the case of a patient who was initially on AZT/3TC for 6 months in 1997 followed by ddI/d4t/IDV combination and who is now in clinical and virological failure? What about adding on an NNRTI - EFZ? Will abacavir be useful here, or will the prior use of ZDV/3TC make it unlikely to be useful? This situation is also in a resource-poor country.
Dr. David Katzenstein responds:
It is likely that this patient developed the M184V mutation and likely a few of the "AZT resistance" mutations while on AZT+3TC and then had a good response to the indinavir ddI/d4T combination. If the patient has been suppressed (> 500 copies/mL by an RNA test) for a long time on ddI/d4T + indinavir, then it is unlikely that he or she has developed extensive nucleoside resistance. If there has been a long period of virologic "failure" (on ddI/d4T and indinavir) then the probabilities of NRTI resistance and the "fixation" of M184V are much higher.
To choose an additional drug to add to a salvage regimen with indinavir/lopinavir +EFV, you could certainly consider abacavir, although (if it is available) the new nucleotide analog tenofovir would be a convenient alternative. If cost is not limiting, continuing 3TC + either abacavir or tenofovir may provide additional activity.
