SUV is a mathematically derived ratio of tissue radioactivity concentration and the injected dose of radioactivity per kilogram of the participant's body weight at a given point in time. SUV was analyzed for each region of interest (ROI) such as liver, kidney, muscle, spleen, heart, lung, bladder, thymus, and if feasible blood and bone. A maximum of 4 PET scans were conducted in each participant. Mean SUV derived from PET-CT has been presented.

Pharmacokinetic (PK) Population comprised of participants in the Safety Population for whom a PK sample was obtained and analyzed, and/or for which a PET scan was completed. Only those participants available at the specified time points were analyzed represented by n=X in the category titles.

Volume of ROI is the volume specified in organs as measured in PET or CT images. Mean volume of ROI for each organ has been presented.

PK Population. Only those participants available at the specified time points were analyzed represented by n=X in the category titles.

PK parameters included AUC (0-t) and AUC (0-inf). AUC (0-t) and AUC (0-inf) for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting. AUC (0-t) and AUC (0-inf) for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included AUCex and AUMCex. AUCex and AUMCex for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting. AUCex and AUMCex for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included Cmax. Cmax for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included Cmax. Cmax for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included t1/2 and MRT. t1/2 and MRT for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting. t1/2 and MRT for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included lambda-z. Cmax for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included Vss and Vz. Vss and Vz for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting. Vss and Vz for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included AUMC (0-inf) and AUMC (0-t). AUMC (0-inf) and AUMC (0-t) for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included AUMC (0-inf) and AUMC (0-t). AUMC (0-inf) and AUMC (0-t) for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

PK parameters included clearance. Clearance for 89Zr-GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by scintillation counting. Clearance for GSK3128349 was calculated from the whole blood and plasma concentration-time data, measured by mass spectrometry.

PK Population. Only those participants available at the specified time points were analyzed.

Organ dose was defined as the amount of radiation delivered to a particular organ. Effective dose was defined as the tissue-weighted sum of the organ doses in all specified tissues and organs of the human body. The organ and effective dose is a fraction of milliSievert (mSv) and MegaBecquerel (MBq). The mean relative uptake of 89Zr-GSK3128349 in different organs for all participants across all PET scans is presented.

PK Population. Only those participants available at the specified time points were analyzed.

AE is any untoward medical occurrence in a participant or clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a medicinal product. For marketed medicinal products, this also includes failure to produce expected benefits (i.e., lack of efficacy), abuse or misuse. SAE is any untoward medical occurrence that, at any dose results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, or is a congenital anomaly/birth defect or is medically significant or is associated with liver injury or impaired liver function.

Safety Population which comprised of all participants who received a dose of 89Zr-GSK3128349.

The potential clinical concern range for clinical chemistry parameters were: glucose (low: < 3 millimole [mmol]/L and high: > 9 mmol/L), creatinine (high: Change from Baseline or Day 1 should be positive and > 44.2 mmol/L), phosphorous (low: < 0.8 mmol/L and high: > 1.6 mmol/L), magnesium (low: < 0.5 mmol/L and high: > 1.23 mmol/L), calcium (low: <2 mmoL/L and high: > 2.75 mmol/L), carbon dioxide content (low: < 18 mmol/L and high: > 32 mmol/L), albumin (low: < 30 mmol/L), potassium (low: < 3.0 mmol/L and high: > 5.5 mmol/L) and sodium (low: < 130 mmol/L and high: > 130 mmol/L). Number of participants with clinical chemistry abnormalities of potential clinical importance are presented

Safety Population.

The potential clinical concern range for hematology parameters were: Hemoglobin (low: > 25 gram per Liter change from Baseline/Day 1 and high: > 180 gram per Liter), lymphocytes (low: < 0.8 gigacells/L), hematocrit (low: > 0.075 ratio change from Baseline and high: > 0.54 ratio), neutrophil count (low: < 1.5*10^9/Liter), platelet count (low: < 100 gigacells/L and high: > 550 gigacells/L), white blood cell (WBC) count (low: < 3 gigacells/L and high: > 20 gigacells/L). Number of participants with hematology abnormalities of potential clinical importance are presented.

Safety Population.

ECG measurements were made with the participant in a supine position having rested in this position for at least 5 minutes before each reading. Triplicate 12-lead ECGS were obtained pre dose at Day 1 and single 12-lead ECGs will be obtained at other time points during the study. The potential clinical concern range for ECG parameters was as follows: Absolute corrected QT (QTc) interval (lower: >450 milliseconds [msec], >450 msec, >=480 msec and >=500 msec) and (higher: <=479 msec and <=499 msec); absolute PR interval (lower: <110 and higher >220 msec) and absolute QRS interval (lower: <75 msec and >110 msec). Number of participants with ECG values of potential clinical concern are presented.

Safety Population.

Vital signs included pulse rate, systolic and diastolic blood pressure and body temperature. All vital sign measurements were made with the participant in a supine position and rested in this position for at least 5 minutes before each reading. The potential clinical concern range for systolic blood pressure: <85 and >160 millimeters of mercury (mmHg), for diastolic: <45 and >100 mmHg and heart rate: <40 and >110 beats per minute. Number of participants with vital signs of potential clinical concern are presented.

Safety Population.

Blood samples for testing antibodies against GSK3128349 will be collected on Day 1 (pre-dose) and on Day 43. The actual date and time of each blood sample collection was recorded. The first blood sample was taken pre-dose on Day 1 to determine the presence, if any, of pre-existing Anti Drug Antibodies (ADAs). The presence of such antibodies was assessed using an electrochemiluminescent (ECL) immuno assay. If sera contain anti-GSK3128349 antibodies, they were further analyzed for the antibody specificity and titres. Number of participants who were found to have anti-GSK3128349 antibodies are presented.

Safety Population.

Blood samples for testing antibodies against GSK3128349 will be collected on Day 1 (pre-dose) and on Day 43. The actual date and time of each blood sample collection was recorded. The first blood sample was taken pre-dose on Day 1 to determine the presence, if any, of pre-existing ADAs. The presence of such antibodies and serum titers of anti-GSK3128349 antibodies was assessed using an ECL immuno-assay. If sera contain anti-GSK3128349 antibodies, they were further analyzed for the antibody specificity and titers.

Safety Population. Only those participants with positive anti-GSK3128349 antibody assay were analyzed.