Gilead's Lenacapavir: Twice-Yearly HIV PrEP Could Be a $5B Product

Gilead Sciences already dominates HIV treatment with Biktarvy and Descovy. Lenacapavir could make Gilead the leader in HIV prevention — a market that’s barely been tapped.

The drug

Lenacapavir is a first-in-class capsid inhibitor — it targets the HIV capsid protein, disrupting multiple stages of the viral life cycle. It’s administered as a subcutaneous injection every six months.

For HIV PrEP (pre-exposure prophylaxis), lenacapavir would be the first twice-yearly preventive option. Current PrEP requires daily pills (Truvada, Descovy) or bimonthly injections (Apretude). A six-month injection could solve the adherence problem that limits PrEP uptake.

The data

The PURPOSE 2 trial enrolled 3,200 participants at high risk of HIV infection. Results:

• 0 infections in the lenacapavir group (n = 2,184)
• Standard of care comparison: 99% relative risk reduction vs. background incidence
• Safety: No serious adverse events related to the drug

The PURPOSE 1 trial (announced in 2024) showed the same result: 0 infections in 2,134 women. Two trials, 5,300+ participants, 0 infections. The efficacy is unprecedented.

The market

Global PrEP uptake is low. Of the 1.2 million people who could benefit from PrEP in the US, only ~300,000 are on it. The barriers: daily pill fatigue, stigma, and access.

A twice-yearly injection removes the adherence barrier. If lenacapavir is approved for PrEP, the market could expand 3–5x. Peak PrEP sales estimates range from $3–5 billion globally.

Gilead is also running the STAR study to test lenacapavir as a twice-yearly treatment (not just prevention) for people who already have HIV. That’s a separate $5B+ opportunity.

The risk

The science is strong. The risk is commercial:

1. Pricing: Lenacapavir is expensive to manufacture. If Gilead prices it too high, access programs and generics manufacturers (in developing countries) could limit revenue.
2. Access: Gilead has committed to licensing lenacapavir to generic manufacturers for 120 low-income countries. This is good for public health but limits the revenue model.
3. Competition: ViiV Healthcare’s cabotegravir (Apretude) is a bimonthly PrEP injection. Lenacapavir’s twice-yearly dosing is better, but Apretude has a head start.

What we’re watching

1. Phase 3 data (Q4 2026): Confirmatory data from the STAR study (twice-yearly treatment use).
2. PrEP filing: Gilead is expected to file for PrEP approval in 2027 based on the Purpose trials.
3. Pricing strategy: Will Gilead price lenacapavir at a premium to daily PrEP? At parity? The pricing decision will shape the market.
4. Access deals: Gilead’s licensing agreements for developing countries will affect both public perception and revenue.

Gilead’s stock is up 4% YTD, and lenacapavir is a key growth story beyond the oncology portfolio. The HIV franchise isn’t going away — it’s evolving.