The goal of this clinical study is to look at how lenacapavir (LEN) passes through the body and to assess the safety of LEN and emtricitabine/tenofovir disoproxil fumarate (F/TDF) for prevention of HIV in the cisgender women in the US.

The primary objectives of this study are: 1) to characterize the pharmacokinetics (PK) of LEN in United States (US) cisgender women; 2) to evaluate the safety of LEN and F/TDF for pre-exposure prophylaxis (PrEP) in US cisgender women; and 3) to evaluate the general acceptability of LEN injections and oral F/TDF in US cisgender women.

Key Inclusion Criteria:

• Report at least 1 episode of condomless vaginal or anal sex with a cisgender man in the 12 months before enrollment.

• Hepatitis B virus (HBV) surface antigen (HBsAg) negative.

• Self-report one or more of the following in the past 12 months (except for incarceration, which could have occurred in the past 5 years):

  1) Noninjection recreational drug use (ecstasy, cocaine, crack cocaine, methamphetamine, ketamine, 3,4-methylenedioxy-methamphetamine, or prescription drugs apart from those prescribed by a licensed provider); 2) Alcohol dependence (defined as Cut Down, Annoyed, Guilty, and Eye Opener score of 2); binge-drinking, defined as 4 or more drinks at a time; 3) History of STIs, such as gonorrhea, chlamydia, or syphilis; 4) Exchange of sex for commodities, such as drugs, money, or shelter; 5) Incarceration (jail or prison > 24 hours within the past 5 years); 6) Two or more sexual partners who were assigned male at birth; 7) Sexual partner assigned male at birth with history of either injection or noninjection recreational drug use, sexually transmitted infections (STIs), human immunodeficiency virus (HIV) diagnosis or unknown HIV status, additional sex partners during the course of his sexual relationship with the individual, or incarceration (jail or prison > 24 hours within the past 5 years)

• Negative local rapid HIV-1/2 antibody (Ab)/antigen (Ag) test, central HIV-1/2 Ab/Ag, and HIV-1 RNA quantitative nucleic acid amplification testing (NAAT).

• Estimated glomerular filtration rate (GFR) at least 60 mL/min at screening according to the Cockcroft-Gault formula for creatinine clearance (CLcr).

Key Exclusion Criteria:

• Self-reported history of previous positive results on an HIV test.
• One or more reactive or positive HIV test result at screening or enrollment, even if HIV infection is not confirmed.
• Past or current participation in HIV vaccine or HIV broadly neutralizing antibody study unless individual provides documentation of receipt of placebo (ie, not active product).
• Prior use of long-acting systemic pre-exposure prophylaxis (PrEP) (including cabotegravir (CAB) or islatravir studies).
• Acute viral hepatitis A or acute or chronic hepatitis B or C infection.
• Severe hepatic impairment or a history of or current clinical decompensated liver cirrhosis (eg, ascites, encephalopathy, variceal bleeding, etc).

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Cisgender female