Accumulation of HIV-1 Drug Resistance Mutations After First-Line Immunological Failure to Evaluate the Options of Recycling NRTI Drugs in Second-Line Treatment: A Study from South India.

Lack of HIV-1 viral load monitoring in resource-limited settings leads to the development of HIV drug resistance mutations, although WHO recommends viral load testing for monitoring as this helps in preserving future treatment options and also avoid unnecessary switching to more expensive drugs. A total of 101 patients attaining first-line treatment failure (FTF) were followed until second-line treatment failure (STF) to study the rate of accumulation of thymidine analogue mutations (TAMs), their future drug options, and genetic evolution. The result shows that predominant nucleos(t)ide reverse transcriptase inhibitor (NRTI) mutations were M184V/I (87.3% in FTF and 79% in STF) followed by TAMs (53.4% in FTF and 54.5% in STF). The rate of accumulation of TAMs was higher for a patient with TAMI [0.015 TAM per person-month (TPPM)], TAMII (0.042 TPPM), and 1 (0.005 TPPM) or 2 TAMs (0.008 TPPM) compared with a patient with both TAMs and 3 or >3 TAMs. Future ART options show that >50% of the patients can be considered for choices to recycle NRTIs in the second-line, and third-line therapy. We conclude that the patients who initiated thymidine analogue-based first-line before 2010 can be very well opted for AZT- and TDF-based second-line regimen in the future.