Clinical outcomes associated with once daily ritonavir-boosted darunavir in HIV infected patients harboring single or multi-class resistant virus

BACKGROUND: Limited data exist on the use of a potent boosted protease inhibitor plus <2 active nucleotide reverse transcriptase inhibitors without use of additional classes of ART in treatment experienced patients with background resistance. We evaluated the clinical outcomes in HIV-infected patients harboring single or multi-class resistant virus (NRTI ± PI and/or NNRTI) treated with once daily darunavir/ritonavir (DRV/r) plus tenofovir/emtracitabine (TDF/FTC). METHODS: This was a single-center, retrospective chart review of HIV-1 infected patients harboring single or multi-class resistant virus and receiving an ART regimen of TDF/FTC plus DRV/r administered as a once daily regimen > 24 weeks. The primary outcome was HIV viral load (VL) < 200 copies/mL (cp/mL) at last measurement. Additional endpoints included virologic rebound, re-suppression, and/or failure; VL < 40 cp/mL at last measurement; development of additional mutations. Virologic failure (VF) was defined as failure to achieve a VL < 200 cp/mL or achievement of VL < 200 cp/mL but with rebound to > 200 cp/mL on all successive VLs. RESULTS: 34 of 387 patients meet criteria for inclusion in the study and were receiving DRV 800 mg daily/r 100 mg daily with fixed combination TDF/FTC. All patients had baseline resistance to FTC (M184V/I), 12 (35.3%) had resistance to TDF, and none had high level DRV resistance. 27 (79%) achieved a VL < 200 cp/mL and 25 (74%) had a VL < 200 cp/mL at the last reading. 23 (68%) achieved a VL of < 40 cp/mL. VF occurred in 8/34 patients (24%) with the following baseline parameters: TDF resistance (2/8), low/ intermediate DRV resistance (2/8), and VL > 100,000 cp/mL (3/8). Both patients with baseline DRV resistance and VF demonstrated high level resistance to DRV on repeat genotype testing. Adherence was considered a major contributor to VF. CONCLUSION: The use of once daily DRV/r plus TDF/FTC in treatment experienced patients with single/multi-class resistant virus resulted in virologic suppression in over two-thirds of patients. VF was seen in nearly 25% of patients including development of high level DRV resistance. This combination is a potentially viable option in a patient population seeking a once-daily option to improve adherence. DISCLOSURES: All authors: No reported disclosures.