Transmitted Antiretroviral Drug Resistance to Integrase Strand Transfer Inhibitors Class in São Paulo Metropolitan Area, Brazil.

A newer integrase strand transfer inhibitor (INSTI) cabotegravir was recently approved for both therapy and prophylaxis and can play an essential role in the fight against AIDS. It shares similar resistance profile to dolutegravir, the cornerstone of Brazilian antiretroviral (ARV) treatment, with about 600 thousand people living with HIV in Brazil currently on regimens that contain this INSTI. Health services in the São Paulo metropolitan area are responsible for a large proportion of ARV dispensation in the country. Estimating transmitted drug resistance mutation (TDRM) in the area before cabotegravir introduction may provide a useful baseline information. Partial HIV-1 gene was sequenced (Sanger) from 192 newly diagnosed individuals from São Paulo and nearby cities (2020 to March 2023) at integrase, with 85 also at protease/reverse transcriptase regions. Retrotranscribed plasma RNA, amplified with nested PCR, was edited (Recall or Sequencher) and analyzed at Rega and Stanford db. Surveillance drug resistance mutations (SDRM) to INSTI class was detected in three cases (1.6%; 95% CI: 0.5%-5%), two E138K and one R263K, with 7.8% (95% CI: 5%-13%) with resistance mutations (major or accessory). SDRM for nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and PI classes were identified in 7 (8.2% CI: 95% 4%-16%) cases. Subtype B predominated (69%), followed by subtype C (16%), now the second most prevalent infection in this area. Among 131 patients treated for over 6 months, 92% were virally suppressed below 200 copies/mL, with low TCD4 counts independently associated to failure. SDRM to INSTI class is rare in the area. Intermediate rates of transmitted resistance to other ARV classes are comparable to previous estimates. Viral suppression rates may depend on TCD4 counts, another negative impact of late diagnosis in care that deserves more attention.