A Phase 2 Clinical Study to Evaluate the Pharmacokinetics, Safety, and Efficacy of Doravirine and Doravirine/Lamivudine/Tenofovir Disoproxil Fumarate in Participants With HIV-1, Who Are 4 Weeks to Less Than 12 Years of Age and Weigh Less Than 45 kg
This is a single-group, open-label, multi-site study in pediatric participants with human immunodeficiency virus type 1 (HIV-1) infection, aged 4 weeks to \<12 years and weighing \<45 kg, who are treatment-naive (TN) or have been virologically suppressed (VS) on stable combination antiretroviral therapy (cART) for ≥3 months with no history of treatment failure. The primary objectives are: * To evaluate the steady state pharmacokinetics (PK) of doravirine (DOR) \[MK-1439\] when given in combination with 2 nucleoside/nucleotide analog reverse transcriptase inhibitors (NRTIs) or as part of the fixed-dose combination (FDC) of DOR/lamivudine (3TC)/tenofovir disproxil fumarate (TDF) in participants ≥6 to \<12 years and weighing ≥14 to \<45 kg. * To evaluate the safety and tolerability of DOR when given with 2 NRTIs or as part of the FDC of DOR/3TC/TDF, in participants ≥6 to 12 years and weighing ≥14 to \<45 kg, through Week 24.
• Has human immunodeficiency virus type 1 (HIV-1) infection confirmed at screening
• Has appropriate treatment history defined as treatment-naïve (TN) or with documented virologic suppression (HIV-1 ribonucleic acid \[RNA\] \<50 copies/mL) on stable combination antiretroviral therapy (cART) for ≥3 months
• Body weight is \>3 kg to \<45 kg
• If female, is not pregnant or breastfeeding, and one of the following applies:
• Is not a woman of childbearing potential (WOCBP)
• Is a WOCBP using an acceptable form of contraception, or is abstinent
• If a WOCBP must have a negative pregnancy test (urine or serum) within 24 hours of the first dose of study intervention
⁃ Study Extension Inclusion Criteria:
• Has completed the Week 96 visit
• Is considered, in the opinion of the investigator, to have derived benefit from treatment with doravirine (DOR) plus the 2 nucleoside/nucleotide analog reverse transcriptase inhibitor (NRTIs) selected by the investigator, or doravirine/lamivudine/tenofovir disoproxil fumarate (DOR/3TC/TDF), by Week 96 of the study
• Is considered, in the opinion of the investigator, to be a clinically appropriate candidate for additional treatment with DOR regimens (DOR plus 2 NRTIs selected by the investigator or DOR/3TC/TDF)
• Understands the procedures in the study extension and has provided (or have the participant's legally acceptable representative, if applicable, provide) documented informed consent/assent to enter the study extension and continue treatment with DOR regimens (DOR plus 2 NRTIs selected by the investigator or DOR/3TC/TDF) until it is available locally in countries participating in the study or for up to an additional 224 weeks (whichever comes first)