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VIROLOGIC RESPONSE TO 2-DRUG ART REGIMENS AMONG TREATMENT-EXPERIENCED HIV+ PATIENTS
Gerald Pierone1, Cassidy Henegar2, Jennifer Fusco2, Vani Vannappagari3, Michael Aboud4, Leigh Ragone3, Gregory Fusco2
1Whole Family Health Center, Vero Beach, FL, USA,2Epividian, Durham, NC, USA,3ViiV Healthcare, Research Triangle Park, NC, USA,4ViiV Healthcare, London, UK
Drug-sparing regimens have the potential to reduce complexity, toxicity, and cost of antiretroviral therapy (ART). Our objectives were to describe two-drug regimen (2-DR) use among ART-experienced HIV+ patients in a large clinical cohort, and to compare virologic outcomes of 2-DRs and three-drug regimens (3-DRs) following switch during the study period.
Between 1/1/2010 and 6/30/2016, ART-experienced patients starting a new 2-DR or 3-DR, were selected from the OPERA cohort. Patients were observed from regimen start date (baseline) until regimen discontinuation (d/c), loss to follow-up, death, or study end (6/30/2017). Outcomes were stratified by viral load (VL) at baseline (switched while viremic: ≥50 copies/mL; stable switch: <50 copies/mL). Suppression during follow-up was defined as a VL <50 copies/mL; failure following suppression was defined as 2 consecutive VLs >200 copies/mL or a VL>200 copies/mL + d/c. Cox models for each outcome were fit to estimate adjusted hazard ratios (aHRs).
We identified 10,190 ART-experienced patients who switched during the study period; 1,337 (13%) switched to a 2-DR, and 8,853 (87%) to a 3-DR. At baseline, 2-DR patients were older, more likely to have AIDS, had been on ART longer and experienced more treatment lines, had more comorbidities, and were less likely to be a stable switch compared to 3-DRs (p<0.0001). The most common 2-DRs (55%) comprised a protease inhibitor and an integrase strand transfer inhibitor combination, regardless of baseline VL. Among those switching while viremic (2-DR: 612 (15%), 3-DR: 3566 (85%)), suppression during follow-up was comparable among patients on 2-DRs (61%) and 3-DRs (67%; aHR 1.00, 95% CI 0.88, 1.13) [Figure]. After achieving suppression during follow-up, 13% of 2-DR and 15% of 3-DR patients went on to experience a failure event. Among stable switch patients (2-DR: 723 (12%), 3-DR: 5285 (88%)), the difference in risk of virologic failure during follow-up was not statistically significant between 2-DR and 3-DR patients (10% vs. 11%; aHR 1.15, 95% CI 0.90, 1.48) [Figure].
Virologic outcomes were comparable between ART-experienced patients switching to two- and three-drug regimens, regardless of whether patients were virologically controlled at switch. These findings support the continued evaluation of 2-DRs in clinical trials and real-world settings. Long-term outcomes require further assessment.