**Study of Lenacapavir as a Once-Yearly Injection for HIV Pre-exposure Prophylaxis (PrEP)** This study aims to understand how the medicine **lenacapavir (LEN)**, given as a shot once a year, helps prevent HIV. HIV, or Human Immunodeficiency Virus, is a virus that can lead to the disease AIDS. **PrEP** stands for **Pre-exposure Prophylaxis**, which means taking medicine to prevent getting HIV. The study will look at how LEN is absorbed, changed, and removed by the body. To join the study, you must be at least 16 years old and have had certain types of sexual activity in the past 6 months. You cannot participate if you show signs of HIV or have certain liver problems. You also should not have taken some forms of LEN recently or participated in certain HIV studies before. **Key Points:** - The study involves getting a shot once a year. - You need to be willing to have regular medical check-ups. - The study is only for those who are not currently showing signs of HIV infection.