Genotypic analysis of second-line failures
Genotypic resistance testing was carried out among 24 participants (15 participants in the SOC arm vs 9 participants in the clinic-based assay arm) persistently failing a PI-based second-line regimen: atazanavir/ritonavir in 12, lopinavir/ritonavir in 11. One participant, who did not have PI or InSTI resistance mutations, was on darunavir + raltegravir + lamivudine/tenofovir disoproxil fumarate. Altogether, DRMs were identified in 19 of 24 (79%) participants, with 87% (13/15) in the SOC arm versus 67% (6/9) in the clinic-based SAMBA assay arm (p = 0.326, Fisher’s exact test).Major DRMs to PIs were identified in only 4/19 (21%). Resistance to NNRTIs was found in 17/19 (89%) of the participants, with G190A being the most common mutation, found in 8 (42%) participants. The most common NRTI mutation was M184V in 12/19 (63%). Dual class resistance to NRTIs and NNRTIs was detected in 10 (53%) participants, and 3/19 (16%) had multiclass drug resistance to PIs, NRTIs, and NNRTIs. Thymidine analogue mutations were less common in these 3 participants: Two had only a T215Y mutation and the other had the M41L and T215Y mutations.