I have heard about the emergence of a new K65R mutation that seems to
present in patients on triple NRTI therapy. In the case of a patient on ddI,
tenofovir and 3TC, should I be worried about K65R?
A prior genotype showed M41L and L210L/W, and he is happy on his current regimen with a viral load of approximately 400 copies/mL.
Dr. Mark A. Wainberg responds:
You should at least be aware of the possibility that a K65R mutation may develop, and that this might lead to a rise in viral load. Since the patient is now doing well and likes the ddI/TDF/3TC regimen (as do I), I would not change anything right now. But keep watching because a K65R would probably be bad news for the TDF. Incidentally, K65R is not a new mutation-it was first described in 1994 in regard to ddC. What is new is its growing clinical relevance as a consequence of increased TDF usage.
