Sunlenca (Lenacapavir) Monotherapy for HIV
Sunlenca (lenacapavir) should never be used as monotherapy for HIV treatment. Monotherapy with any antiretroviral agent, including lenacapavir, is contraindicated due to high rates of virologic rebound and rapid development of resistance mutations 1.
Why Monotherapy is Contraindicated
Rapid resistance development: Clinical trial data from the CAPELLA study demonstrated that all 8 participants who developed lenacapavir resistance mutations (M66I, K70H, or Q67H + K70R) were receiving unintended functional lenacapavir monotherapy at the time resistance emerged 2.
Historical precedent: Monotherapy with protease inhibitors or integrase strand transfer inhibitors as a maintenance strategy is explicitly not recommended because of higher rates of virologic rebound, often with resistant virus 1.
FDA-approved indication: Lenacapavir is approved only in combination with other antiretroviral agents for treatment of multidrug-resistant HIV-1 infection in heavily treatment-experienced adults 3, 4.
Required Combination Therapy
Lenacapavir must be used with at least one or two additional fully active agents to optimize efficacy and prevent treatment-emergent resistance 5.
For patients with multiclass drug resistance, lenacapavir should be combined with agents from different antiretroviral classes with novel mechanisms of action 6.
The goal is to construct a regimen with at least 2 fully active drugs from different classes whenever possible 6.
Even in heavily treatment-experienced patients with extensive resistance, adding a single active agent to a failing regimen is not recommended 1.
Common Pitfall to Avoid
The most critical error is allowing functional monotherapy to occur, even unintentionally. This can happen when:
- Companion drugs in the regimen have poor adherence (particularly self-administered oral medications) 5.
- Background regimen drugs are not fully active due to pre-existing resistance 2.
- Drug-drug interactions reduce the effectiveness of companion antiretrovirals 5.
Adherence support is critical for companion drugs to prevent the scenario of functional lenacapavir monotherapy, which rapidly selects for resistance 5.
Clinical Context
While lenacapavir's long-acting formulation (subcutaneous administration every 6 months) offers significant advantages for adherence compared to daily oral regimens 7, 8, this does not justify its use alone. The extended half-life (8-12 weeks) actually increases the risk if resistance develops, as subtherapeutic drug levels persist for prolonged periods 7.