Classification and Mechanism of Action

Lenacapavir belongs to a new class of antiretroviral drugs known as capsid inhibitors.

The HIV capsid is a protein shell that protects the viral genetic material and plays a critical role during viral replication. Lenacapavir binds directly to the capsid protein and interferes with several stages of the viral life cycle, including:

1. Nuclear transport of viral DNA
2. Viral integration
3. Capsid assembly
4. Virus maturation and release

By targeting multiple replication steps simultaneously, lenacapavir remains effective even against HIV strains resistant to other antiretroviral drug classes.

Indications for Use

Lenacapavir currently has two major clinical roles:

1. Treatment of Multidrug-Resistant HIV Infection

Lenacapavir is approved for use in combination with other antiretroviral agents in heavily treatment-experienced adults with:

• Multidrug-resistant HIV
• Virologic failure
• Limited treatment options

It is not used as monotherapy for treatment but as part of combination therapy

2. HIV Pre-Exposure Prophylaxis (PrEP)

Lenacapavir is now recommended as a long-acting injectable option for HIV prevention.

In 2025:

• The FDA approved lenacapavir for PrEP
• The World Health Organization (WHO) recommended it globally
• It became the first twice-yearly injectable PrEP medicine

This represents a major shift from daily oral PrEP regimens.