Switching from Prezcobix + Tivicay to Biktarvy
Yes, a virologically suppressed patient on Prezcobix (darunavir/cobicistat) and Tivicay (dolutegravir) can be switched to Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide), provided there is no documented integrase inhibitor resistance and creatinine clearance is ≥30 mL/min.
Key Considerations Before Switching
Before making this switch, you must review several critical factors 1:
- Resistance testing history: Confirm no prior NRTI or integrase inhibitor resistance mutations
- Hepatitis B co-infection status: If HBV positive, the switch is appropriate as Biktarvy contains tenofovir alafenamide and emtricitabine (both active against HBV)
- Renal function: Biktarvy requires CrCl ≥30 mL/min 2
- Co-medications: Review for drug-drug interactions, particularly since you're removing cobicistat (a strong CYP3A4 inhibitor)
Why This Switch Makes Sense
Regimen Simplification
The current regimen (Prezcobix + Tivicay) represents a 4-drug regimen (darunavir + cobicistat + dolutegravir + whatever NRTI backbone is present). Switching to Biktarvy consolidates this into a single-tablet, 3-drug regimen taken once daily, which improves adherence and reduces pill burden.
Evidence Supporting the Switch
Guideline support: The 2020 IAS-USA guidelines explicitly state that individuals with virologic suppression receiving boosted protease inhibitor regimens plus 2 NRTIs can be switched to dolutegravir or bictegravir-based regimens regardless of known or likely prior NRTI resistance, provided there is no history of integrase inhibitor resistance 3.
Real-world data: A large French cohort study (N=9,827) demonstrated that switching to bictegravir/TAF/FTC in virologically suppressed patients showed no significant increased risk of virologic failure (HR 1.29; 95% CI: 0.97-1.7, p=0.08), even in the presence of tenofovir resistance mutations 4. Importantly, M184V mutations and tenofovir resistance had no effect on virologic failure rates.
Clinical trial data: Multiple studies confirm high efficacy when switching to Biktarvy from various regimens, with virologic suppression rates of 95-96% at 48 weeks 5, 6, 7.
Important Caveats
Resistance Considerations
While the guidelines support this switch even with NRTI resistance 3, patients with documented integrase inhibitor resistance should NOT be switched to Biktarvy 2. Since your patient is currently on dolutegravir (Tivicay), if they have been virologically suppressed, integrase resistance is unlikely.
Monitoring After Switch
- Check HIV viral load at 1 month after switching to ensure maintained suppression 1
- Monitor more closely in the first year if there are any concerns about adherence or if historical NRTI resistance is present 3
Drug-Drug Interactions
Removing cobicistat (a pharmacokinetic booster) may affect levels of other medications the patient is taking. Biktarvy has minimal drug-drug interactions compared to boosted regimens, which is generally advantageous 8.
Hepatitis B Co-infection
If the patient has HBV co-infection, this switch is particularly appropriate because Biktarvy contains both tenofovir alafenamide and emtricitabine, maintaining dual HBV suppression 1, 9.
Contraindications to This Switch
Do NOT switch if:
- CrCl <30 mL/min (unless on chronic hemodialysis with documented viral suppression) 2
- Documented integrase inhibitor resistance 2
- Severe hepatic impairment (Child-Pugh Class C) 2
- Active virologic failure or HIV RNA >50 copies/mL
Practical Implementation
- Verify viral suppression: Confirm HIV RNA <50 copies/mL for at least 3 months
- Check renal function: Ensure CrCl ≥30 mL/min
- Review resistance history: Confirm no integrase inhibitor resistance
- Assess HBV status: If positive, document that dual HBV therapy will be maintained
- Review co-medications: Adjust doses of drugs previously affected by cobicistat
- Make the switch: Simply discontinue Prezcobix + Tivicay and start Biktarvy 50/200/25 mg once daily
- Follow-up: Check viral load at 4 weeks post-switch
The FDA label explicitly supports using Biktarvy "to replace the current antiretroviral regimen in those who are virologically-suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no known or suspected resistance to bictegravir or tenofovir" 2.