A Proof of Concept Study of GSK3640254 in Human Immunodeficiency Virus-1 (HIV-1) Infected Treatment-naive Adults

Inclusion Criteria:

- Subject must be 18 to 65 years of age inclusive, at the time of signing the informed
consent.

- Subjects who are healthy (other than HIV infection) as determined by the Investigator
or medically qualified designee based on a medical evaluation including medical
history, laboratory tests, and cardiac monitoring.

- Screening Cluster of designation 4 positive (CD4+) T-cell count >=350 cells per
millimeter cube (cells/mm^3).

- Documented HIV infection and Screening plasma HIV-1 RNA >=5000 copies/milliliter (mL).
A single repeat of this test is allowed within a single Screening period to determine
eligibility.

- Treatment-naive: No anti-retrovirals (in combination or monotherapy) received after
the diagnosis of HIV-1 infection.

- Body weight >=50.0 kilograms (kg) (110 Pounds) for men and >=45.0 kg (99 pounds) for
women and body mass index (BMI) within the range 18.5-31.0 kg/meter square (kg/m^2)
(inclusive).

- Male or female: A male subject with a female partner of child-bearing potential or who
is breastfeeding or pregnant must agree to use contraception during the treatment
phase and for at least 14 weeks following the last dose (corresponding to the time
needed to eliminate study treatment for potential genotoxic and teratogenic study
treatments plus an additional 90 days [spermatogenesis cycle]). In addition, male
subjects must refrain from donating sperm during this period. A female subject is
eligible to participate if she is not pregnant, not breastfeeding, and not a woman of
childbearing potential (WOCBP).

- Capable of giving signed informed consent.

- For subjects enrolled in France: a subject will be eligible for inclusion in this
study only if either affiliated to or a beneficiary of a social security category.

Exclusion Criteria:

- Presence of Hepatitis B surface antigen (HBsAg) at screening or within 3 months prior
to starting study treatment.

- Positive Hepatitis C antibody test result at screening or within 3 months prior to
starting study treatment and positive on reflex to Hepatitis C RNA.

- ALT >2 times upper limit of normal (ULN). A single repeat of ALT is allowed within a
single Screening period to determine eligibility.

- Bilirubin >1.5 times ULN (isolated bilirubin >1.5 times ULN is acceptable if bilirubin
is fractionated and direct bilirubin <35 percent).

- Current or chronic history of liver disease, or known hepatic or biliary abnormalities
(with the exception of Gilbert's syndrome or asymptomatic gallstones);

- A pre-existing condition interfering with normal gastrointestinal anatomy or motility
(example given [e.g.], gastroesophageal reflux disease [GERD], gastric ulcers,
gastritis), hepatic and/or renal function, that could interfere with the absorption,
metabolism, and/or excretion of the study drugs or render the subject unable to take
oral study treatment.

- Any acute laboratory abnormality at screen which, in the opinion of the investigator,
should preclude participation in the study of an investigational compound.

- Any Grade 2-4 laboratory abnormality at screen, with the exception of creatine
phosphokinase (CPK) and lipid abnormalities (e.g., total cholesterol, triglycerides,
etc), and ALT (described above), will exclude a subject from the study unless the
investigator can provide a compelling explanation for the laboratory result(s) and has
the assent of the sponsor. A single repeat of any lab abnormality is allowed within a
single screening period to determine eligibility.

- Any pre-existing physical or psychiatric condition (including alcohol or drug abuse),
which, in the opinion of the investigator (with or without psychiatric evaluation),
could interfere with the subject's ability to comply with the dosing schedule and
protocol evaluations or which might compromise the safety of the subject.

- Medical history of cardiac arrhythmias or cardiac disease or a family or personal
history of long QT syndrome.

- History of sensitivity to any of the study medications, or components thereof or a
history of drug or other allergy that, in the opinion of the investigator or Medical
Monitor, contraindicates their participation.

- The subject has participated in a clinical trial and has received an investigational
product within the 30 days prior to the first dosing day in the current study.

- Any positive (abnormal) response confirmed by the investigator on a Screening
clinician- (or qualified designee-) administered Columbia Suicide Severity Rating
Scale (CSSRS).

- Any positive result for illicit drug use (e.g., cocaine, heroin) at Screening. A
positive screen for marijuana is not exclusionary, though if positive for
delta-9-tetrahydrocannabinol (THC).

- Where participation in the study would result in donation of blood or blood products
in excess of 500 mL within 56 days.

- Exposure to more than four new investigational drugs or vaccines within 12 months
prior to the first dosing day.

- Treatment with radiation therapy or cytotoxic chemotherapeutic agents within 30 days
of study drug administration or anticipated need for such treatment within the study.

- Ongoing malignancy other than cutaneous Kaposi's sarcoma, basal cell carcinoma, or
resected, non-invasive cutaneous squamous cell carcinoma, or cervical, anal or penile
intraepithelial neoplasia; or other localized malignancies require agreement between
the investigator and the study medical monitor for inclusion of the subject prior to
randomization.

- Treatment with immunomodulating agents (such as systemic corticosteroids,
interleukins, interferons) or any agent with known anti-HIV activity (such as
hydroxyurea or foscarnet) within 30 days of study drug administration.

- An active Center for Disease Control and Prevention (CDC) Category C disease except
cutaneous Kaposi's sarcoma not requiring systemic therapy during the trial.

- Treatment with any vaccine within 30 days prior to receiving study medication.

- Exclusion criteria for screening electrocardiogram (a single repeat is allowed for
eligibility determination): Heart rate of <45 or >100 beats per minute (bpm) for males
and <50 or >100 bpm for females; PR Interval of <120 or >200 milliseconds (msec) for
both males and females; QRS duration of <70 or >110 msec for both males and females;
QT interval corrected (QTc) for heart rate according to Fridericia's formula (QTcF) of
>450 msec for males and >470 msec for females. A heart rate from 100 to 110 bpm can be
rechecked by electrocardiogram or vitals within 30 minutes to verify eligibility. QTcF
is either machine read or manually over-read.

- Any significant arrhythmia or electrocardiogram finding (e.g., prior myocardial
infarction, sinoatrial pauses, bundle branch block, or conduction abnormality) which,
in the opinion of the Investigator OR ViiV Medical Monitor, will interfere with the
safety for the individual subject.