Gilead Sciences is conducting five clinical trials to test lenacapavir for pre-exposure prophylaxis (PrEP). In 2022, the Food and Drug Administration approved lenacapavir (Sunlenca) for treatment-experienced people with resistant virus. It is also being tested for first-line therapy and HIV prevention. Participants in the PURPOSE trials will receive twice-yearly lenacapavir injections or daily PrEP pills. The studies will compare the rate of HIV acquisition among people who use either form of PrEP against the background rate. PURPOSE 1 enrolled adolescent girls and young women in Africa, while PURPOSE 2 enrolled cisgender and transgender men, transgender women and nonbinary people in the United States and six other countries who have sex with men. PURPOSE 3 and PURPOSE 4 are recruiting U.S. cisgender women and people who inject drugs. Finally, PURPOSE 5 will be conducted in France and the United Kingdom. If found to be effective, lenacapavir could become the longest-acting PrEP option, administered just once every six months.