This study is being conducted to assess the antiretroviral activity of a fixed-drug, single tablet, combination of Bictegravir 50mg/ Emtricitabine 200mg/ Tenofovir alafenamide 25mg (Biktarvy®) dosed twice daily in HIV-1 infected, ART-naïve patients with TB co-infection receiving a rifampicin-based tuberculosis (TB) treatment regimen. This study will assess the activity of Bictegravir and dolutegravir-containing ART regimens in patients with drug-susceptible TB through 48 weeks

Primary objective: To characterize viral suppression rates (proportion of patients with suppressed viral load) at week 24 in the BIC arm

Secondary objectives:

To characterize viral suppression rates at weeks 12, 24 and 48 in the standard of care treatment (SOC) arm (currently, TDF 300mg/3TC 300mg/DTG 50mg) and at weeks 12 and 48 in the BIC/FTC/TAF arm.

To compare the pharmacokinetics (PK) of BIC when given twice daily and co-administered with Rifampicin during tuberculosis treatment vs when given alone after discontinuation of Rifampicin

To assess the incidence of TB associated IRIS in each arm, through week 24.

To characterize the tolerability of treatment in each arm by assessing frequency of clinician-initiated treatment interruptions or switches through week 48.

To assess frequency of ART drug resistance mutations in participants with detectable viral load at study visit weeks 24 and 48.

Inclusion Criteria:

• Adults ≥ 18 years of age with Karnofsky score ≥ 70
• Confirmed rifampicin-susceptible tuberculosis and/or
• On first-line rifampicin-based tuberculosis treatment (not > 8 weeks at the time of enrolment)
• Documented HIV-1 infection, ART-naïve OR ART non-naïve (patients to have no exposure to ART medication at least ≥ 3 months at the time of enrollment)
• Estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m2
• Alanine aminotransferase (ALT) ≤3 times the upper limit of normal (ULN)
• Total bilirubin ≤2.5 times ULN
• Creatinine ≤2 times ULN
• Hemoglobin ≥ 7.0 g/dL (6.5 g/dL for females)
• Platelet count ≥ 50,000/mm3
• Absolute Neutrophil Count (ANC) ≥650/mm3
• Able and willing to provide written informed consent
• Female patients agree to use both a barrier and a non-barrier form of contraception during the study, starting at least 14 days prior to enrolment

Exclusion Criteria:

• Pregnancy or breastfeeding (or planned pregnancy within 12 months of study entry)
• Prior use of antiretroviral drugs for pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP) < 3 months at the time of enrolment
• Hepatitis B surface antigen positive OR Hepatitis B virus (HBV) infection OR active systemic infections (other than HIV-1 infection) requiring systemic antibiotic or antifungal therapy current or within 30 days prior to baseline that could, in the opinion of the investigator, interfere with study procedures or assessment of study outcomes
• Participants with a CD4+ cell count of < 50 cells/ μl
• Any verified Grade 4 laboratory abnormality, with the exception of, Grade 4 triglycerides. A single repeat test is allowed during the Screening period to verify a result
• Patients on metformin (> 500mg, 12hourly)
• Patients with an uncontrolled psychiatric co-morbidity. Patients who, in the investigator's judgment, pose a significant suicidality risk. Recent history of suicidal behavior and/or suicidal ideation may be considered as evidence of serious suicide risk
• Other condition or circumstance deemed by clinician/investigators to be detrimental to patient safety or study conduct
• Unwilling to be part of the main pharmacokinetic (PK) study and have PK blood draws done (NB there is a semi-intensive PK substudy which is optional)

Data generated under this project will be shared in accordance with CAPRISA, and NIH-SAMRC policies, including the NIH Data Sharing Policy. Research data that documents, supports, and validates research findings will be made available after the main findings from the final research data set have been accepted for publication.

Not longer than 12 months after first publication of results. In accordance with WHO stipulations, summary results or a link to summary results will be reported within the trial registration record within 12 months of the study completion date.

Access to databases and associated software tools generated under the project will be available for educational, research, and non-profit purposes from bona-fide researchers and/or research organisations.

From enrollment until end of follow-up, up to 48 weeks

Adverse events defined as DAIDS Toxicity Table

Non-comparative design