GSK2982772 Study in Subjects With Ulcerative Colitis

Inclusion Criteria:

- Between 18 and 75 years of age inclusive, at the time of signing the informed consent.

- Subjects that do not have any medical conditions, other than active UC, that in the
opinion of the Investigator put the subject at unacceptable risk or interfere with
study assessments or integrity of the data. These medical conditions should be stable
at the time of screening and are expected to remain stable for the duration of the
study.

- Subject has had a confirmed diagnosis of active UC, as documented by complete
diagnostic colonoscopy to the terminal ileum (TI) with biopsy performed >=3 months
prior to screening. If diagnostic colonoscopy was not performed to the TI, it must be
documented by the principal investigator that the subject has diffuse inflammation
from the rectum extending proximally to the colon in a continuous and uniform way.

- A Complete Mayo Score of >=3 points and endoscopy sub score of 2 to 3 at screening,
despite concurrent treatment with at least 1 of the following (oral corticosteroids or
any oral 5-aminosalicylates (5-ASA) or purine analogues or all as defined): Oral 5-ASA
at a stable dose (equivalent to >=2.4 grams per day (g/day) of Asacol) for at least 4
weeks prior to first dose. Must remain on a stable dose until end of treatment; Purine
analogues (azathioprine, mercaptopurine, thiopurines) or methotrexate for at least 12
weeks prior to first dose. Must remain on a stable dose until end of treatment; Stable
low dose oral corticosteroid (up to 20 mg prednisolone or equivalent) for 2 weeks
prior to sigmoidoscopy. Must remain on a stable dose until end of treatment.

- If on rectal 5-ASA or corticosteroids, must remain on a stable dose for at least 4
weeks prior to first dose. Must remain on stable dose until the end of treatment.

- Subject is naive to any biological therapies for UC OR Subject may have had previous
exposure to a single anti-tumor necrosis factor (TNF) biologic agent which was
discontinued for reasons other than primary non-response more than 8 weeks (or 5
half-lives whichever is longer) prior to first dose OR Subject may have had previous
exposure to a single biologic agent (example, vedolizumab) in the context of a
previous clinical trial. The biologic agent must have been discontinued more than 8
weeks (or 5 half-lives whichever is longer) prior to first dose. Note: Exposure to a
single biologic agent is not required in addition to inclusion criteria listed above
(number fourth and fifth on the list).

- A body mass index (BMI) within range of 18.5 to 35 kilogram per meter square (kg/m^2)
(inclusive) at screening.

- Male and Female subjects:

Males: Male subjects with female partners of child bearing potential must comply with the
contraception requirements.

Females: A female subject is eligible to participate if she is not pregnant (as confirmed
by a negative serum human chorionic gonadotrophin (hCG) test), not lactating, and at least
one of the following conditions applies:

Non-reproductive potential defined as 1) Pre-menopausal females with one of the following:
Documented tubal ligation; Documented hysteroscopic tubal occlusion procedure with
follow-up confirmation of bilateral tubal occlusion; Hysterectomy; Documented Bilateral
Oophorectomy. 2) Postmenopausal defined as 12 months of spontaneous amenorrhea in
questionable cases a blood sample with simultaneous follicle stimulating hormone (FSH) and
estradiol levels consistent with menopause. Females on hormone replacement therapy (HRT)
and whose menopausal status is in doubt will be required to use one of the highly effective
contraception methods if they wish to continue their HRT during the study. Otherwise, they
must discontinue HRT to allow confirmation of post-menopausal status prior to study
enrolment.

Reproductive potential and agrees to follow one of the options listed in the Modified List
of Highly Effective Methods for Avoiding Pregnancy in Females of Reproductive Potential
(FRP) from 30 days prior to the first dose of study medication and until at least 2 days
after the last dose of study medication and completion of the follow-up visit. The
Investigator is responsible for ensuring that subjects understand how to properly use
methods of contraception.

- Capable of giving signed informed consent which includes compliance with the
requirements and restrictions listed in the consent form and protocol.

Exclusion Criteria:

- Subject with diagnosis of indeterminate colitis, Crohn's Disease, infectious colitis,
or ischemic colitis.

- Subject with fulminant UC, or UC limited to the rectum (disease extent <15 centimeters
(cm) from the anal verge).

- Subject with previous small bowel or colonic surgery(with exception of appendectomy),
histological evidence of colonic dysplasia or bowel stricture.

- Subject with colostomy, fistulae or known symptomatic stenosis of the intestine.

- Subject with toxic megacolon.

- Subject with positive Clostridium difficile toxin test or active/previous colonic
cytomegalo virus (CMV) infection.

- Subject with current history of suicidal ideation behavior (SIB) as measures using the
Columbia Suicide Severity Rating Scale (C-SSRS) or history of attempted suicide.

- An active infection, or a history of infections as follows:

Hospitalization for treatment of infection within 60 days before first dose (Day 1).

Currently on any suppressive therapy for a chronic infection (such as pneumocystis,
cytomegalovirus, herpes simplex virus, herpes zoster and atypical mycobacteria).

Use of parenteral (intravenous (IV) or intramuscular) antibiotics (antibacterials,
antivirals, antifungals, or antiparasitic agents) for an infection within 60 days before
first dose.

A history of opportunistic infections within 1 year of screening (example: pneumocystis
jirovecii, CMV pnemonitis, aspergillosis). This does not include infections that may occur
in immunocompetent individuals, such as fungal nail infections or vaginal candidiasis,
unless it is of an unusual severity or recurrent nature.

Recurrent or chronic infection or other active infection that, in the opinion of the
Investigator might cause this study to be detrimental to the patient.

History of tuberculosis (TB), irrespective of treatment status. A positive diagnostic TB
test at screening defined as a positive QuantiFERON-TB Gold test or T-spot test. In cases
where the QuantiFERON or T-spot test is indeterminate, the subject may have the test
repeated once, but they will not be eligible for the study unless the second test is
negative. In cases where the QuantiFERON or T-spot test is positive, but a follow-up chest
x-ray, locally read by a radiologist, shows no evidence of current or previous pulmonary
tuberculosis, the subject may be eligible for the study at the discretion of the
Investigator and GlaxoSmithKline (GSK) Medical Monitor.

- QTc >450 millisecond (msec) or QTc >480 msec for subjects with bundle branch block at
screening.

- ALT >2 times upper limit of normal (ULN) and bilirubin >1.5 times ULN (isolated
bilirubin >1.5 times ULN is acceptable if bilirubin is fractionated and direct
bilirubin <35 percent) at screening.

- Current active or chronic history of liver or biliary disease (with the exception of
Gilbert's syndrome or asymptomatic gallstones).

- Current or history of renal disease or estimated glomerular filtration rate (GFR) by
Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) calculation <60
milliliter per minute per 1.73 meter square (mL/min/1.73 m^2) at screening.

- Hereditary or acquired immunodeficiency disorder, including immunoglobulin deficiency
unless subject has a documented history of selective immunoglobulin A (IgA)
deficiency.

- A major organ transplant (example: heart, lung, kidney, liver) or hematopoietic stem
cell/marrow transplant.

- Any planned surgical procedure during the study.

- A history of malignant neoplasm within the last 5 years, except for adequately treated
non-metastatic cancers of the skin (basal or squamous cell) or carcinoma in situ of
the uterine cervix that has been fully treated and shows no evidence of recurrence.

- The subject has received treatment with the protocol listed prohibited therapies or
changes to those treatments, within the prescribed timeframe.

Other medications (including vitamins, herbal and dietary supplements) will be considered
on a case-by-case basis, and will be allowed if in the opinion of the Investigator the
medication will not interfere with the study procedures or compromise subject safety.

- History of alcohol or drug abuse that would interfere with the ability to comply with
the study.

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

- Received a live or attenuated vaccine within 30 days of randomization OR plan to
receive a vaccination during the study until 5 half-lives (or 2 days) plus 30 days
after receiving GSK2982772.

- The subject has participated in a clinical trial and has received an investigational
product within 30 days or 5 half-lives, whichever is longer before the first dose of
study medication, or plans to take part in another clinical trial (not inclusive of
any UC registry study where no study medication is being administered) at the same
time as participating in this clinical trial.

- Hemoglobin <10 grams per deciliter (g/dL); hematocrit <30 percent, white blood cell
count <=3,000 per millimeter cube (mm^3) (<=3.0 into 10^9 per liter); platelet count
<=100,000 per microliter (<=100 into 10^9 per liter); absolute neutrophil count <=1.5
into 10^9 per liter.

- Presence of hepatitis B surface antigen (HBsAg), positive hepatitis C antibody test
result at screening or within 3 months prior to first dose of study treatment. As
potential for and magnitude of immunosuppression with this compound is unknown,
subjects with presence of hepatitis B core antibody (HBcAb) should be excluded.

- A positive serology for human immunodeficiency virus (HIV) 1 or 2 at screening.

- Where participation in the study would result in donation of blood or blood products
in excess of 500 mL within 3 months.

- Exposure to more than 4 investigational medicinal products within 12 months prior to
the first dose.