Foundations of ART Management in Heavily Treatment–Experienced Patients

We will now investigate different situations in which we treat people who have underlying drug-resistant virus. The first situation includes those with first-line or second-line treatment failures. These data provide some guidance on how to treat those who are even more experienced.

These are data describing samples submitted to Monogram Biosciences for resistance testing.⁴ They describe the trends in drug resistance in the United States. The figure illustrates the proportion with 1-class, 2-class, 3-class, or 4-class resistance.

As we might have predicted, the greatest proportion have 1-class resistance; a smaller proportion have 2-class resistance; and the 3-class– and 4-class–resistant populations are much rarer.

Note that the trends are either flat or declining in all cases except 1-class resistance. This is consistent with the fact that, in recent years, we have better regimens—often with high barriers to resistance—so that resistant virus is less frequently selected.