Study to Compare an Oral Weekly Islatravir/Lenacapavir Regimen With Bictegravir/Emtricitabine/Tenofovir Alafenamide in Virologically Suppressed People With HIV-1

Key Inclusion Criteria: * HIV-1 RNA \< 50 copies/mL for ≥ 6 months before screening, as documented by: 1. One HIV-1 RNA \< 50 copies/mL immediately preceding the 24 week period prior to screening. 2. Within 24 weeks prior to screening, if HIV-1 RNA results are available, all levels must be \< 50 copies/mL. 3. During the 6 to 12 months period prior to screening, transient detectable viremia ≥ 50 copies/mL is acceptable ("blip"), as long as it is not confirmed on 2 consecutive visits. * Plasma HIV-1 RNA levels \< 50 copies/mL at screening. * Individuals are receiving B/F/TAF for ≥ 6 months prior to screening and willing to continue until Day 1. * Individuals assigned female at birth and of childbearing potential who engage in heterosexual intercourse must agree to use protocol-specified methods of contraception. Key Exclusion Criteria: * Prior virologic failure. * Prior use of, or exposure to ISL or LEN. * Active, serious infections requiring parenteral therapy within 30 days before randomization. * Active tuberculosis infection. * Acute hepatitis within 30 days before randomization. * Hepatitis B virus (HBV) infection as determined below at the screening visit: 1. Positive HBV surface antigen OR 2. Positive HBV core antibody and negative HBV surface antibody. Note: individuals found to be susceptible to HBV infection (eg negative hepatitis B surface antibody at the screening visit, regardless of prior HBV vaccination history) should be recommended to receive HBV vaccination. * Active hepatitis C virus (HCV) coinfection, defined as detectable HCV RNA. Note: individuals with prior/inactive HCV infection (defined as undetectable HCV RNA) may be enrolled. * Any of the following laboratory values at screening: 1. Creatinine clearance (CLcr) ≤ 30 mL/min according to the Cockcroft-Gault formula 2. Alanine aminotransferase \> 5 x upper limit of normal (ULN) 3. Direct bilirubin \> 1.5 x ULN 4. Platelets \< 50,000/μL 5. Hemoglobin \< 8.0 g/dL Note: Other protocol defined Inclusion/Exclusion criteria may apply.