An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a study treatment, whether or not considered related to the study treatment. SAE is defined as any untoward medical occurrence that, at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent disability/incapacity, or is a congenital anomaly/birth defect, other situations which involved medical or scientific judgment or is associated with liver injury and impaired liver function. SAEs are subset of AEs. A summary of number of participants with any AEs and SAEs is presented. AEs were coded using the Medical Dictionary for Regulatory Affairs (MedDRA dictionary).

The data for number of participants withdrawn due to AEs have been presented.

DLT is considered to be clinically relevant AE by investigator if it met at least one of the criteria: Grade(G)3 neutropenia for \>=5 days/G4 neutropenia of any duration, G3 or greater febrile neutropenia, G4 or greater anemia of any duration and thrombocytopenia, or G3 thrombocytopenia with bleeding, Alanine aminotransferase (ALT) \>3x upper limit of normal (ULN)+bilirubin, \>=2xULN or ALT between 3-5 X ULN with bilirubin \< 2Xuln but with hepatitis symptoms/rash, G3 nausea/vomiting/diarrhea that does not improve within 72 hour, G4 or greater nausea/vomiting/diarrhea, G3 or greater hypertension, G3 or greater clinically significant non-hematologic toxicity per National Cancer Institute -- Common Terminology Criteria for Adverse Events (NCICTCAE), Inability to receive at least 80% of scheduled doses in the DLT observation period due to toxicity, G2 or higher toxicity that occurs beyond 21 days which in the judgment of the investigator and GSK Medical Monitor was considered to be a DLT.

The number of participants who experienced any dose modifications (interruptions and reductions) of GSK3326595 have been presented.

Blood samples were collected for evaluation of clinical chemistry parameters. The summaries of worst-case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. The number of participants with decreases to low, changes to normal or no changes from Baseline, and increases to high values have been presented. Participants were counted twice if the participants have values that changed 'To Low' and 'To High', so the percentages may not add to 100%.

Blood samples were collected for evaluation of hematology parameters. The summaries of worst-case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v5.0. The number of participants with decreases to low, changes to normal or no changes from Baseline, and increases to high values have been presented. Participants were counted twice if the participants have values that changed 'To Low' and 'To High', so the percentages may not add to 100%.

Blood samples were collected for evaluation of coagulation parameters. The summaries of worst-case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v4.0. The number of participants with decreases to low, changes to normal or no changes from Baseline, and increases to high values have been presented. Participants were counted twice if the participants have values that changed 'To Low' and 'To High', so the percentages may not add to 100%.

Urine samples were collected for evaluation of urinalysis parameters. The summaries of worst-case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v5.0. The number of participants with no change or change to negative and change to positive have been presented.

Urine samples were collected from participants to assess urine pH levels.

Urine samples were collected from participants to assess urine specific gravity.

The abnormal vital sign ranges are: Heart Rate:- Low (\<60 beats per minute (bpm)), Normal (\>=60 bpm to \<=100 bpm), High (\>100 bpm); Temperature:- Low (\<=35 degree Celsius (°C)), Normal (\>35 °C and \<38 °C), High (\>=38 °C); Systolic Blood Pressure:- Low (\<90 millimeter of mercury (mmHg)), Normal (\>=90 mmHg to \<120 mmHg), High (\>=120 mmHg); Diastolic Blood Pressure:- Low (\<60 mmHg), Normal (\>=60 mmHg to \<80 mmHg), High (\>=80 mmHg). Participants were counted in the worst-case category and their value changes to (low, normal or high), unless there is no change in their category. Participants whose value category was unchanged (e.g., High to High), or whose value became normal, are recorded in the "To Normal or No Change" category. Participants were counted twice if the participants have values that changed 'To Low' and 'To High', so the percentages may not add to 100%.

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a study treatment, whether or not considered related to the study treatment. SAE is defined as any untoward medical occurrence that, at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent disability/incapacity, or was a congenital anomaly/birth defect, other situations which involve medical or scientific judgment or is associated with liver injury and impaired liver function. SAEs are subset of AEs. A summary of number of participants with any AEs and SAEs is presented. AEs were coded using the MedDRA dictionary.

The data for number of participants withdrawn due to AEs have been presented.

The number of participants who experienced any dose modifications (interruptions and reductions) of GSK3326595 and pembrolizumab have been presented.

Blood samples were collected for evaluation of clinical chemistry parameters. The summaries of worst case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v5.0. The number of participants with decreases to low, changes to normal or no changes from Baseline, and increases to high values have been presented.

Blood samples were collected for evaluation of hematology parameters. The summaries of worst case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v5.0. The number of participants with decreases to low, changes to normal or no changes from Baseline, and increases to high values have been presented.

Blood samples were collected for evaluation of coagulation parameters. The summaries of worst case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v5.0. The number of participants with 'decreases to low', 'changes to normal' or 'no changes from Baseline', and 'increases to high' values have been presented.

Urine samples were collected for evaluation of urinalysis parameters. The summaries of worst case change from Baseline with respect to normal range have been presented for only those laboratory tests that are gradable by CTCAE v5.0. The number of participants with no change or change to negative and change to positive values have been presented.

Urine samples were collected from participants to assess urine pH levels.

Urine samples were collected from participants to assess urine specific gravity.

The abnormal vital sign ranges are: Heart Rate:- Low \[\<60 bpm\], Normal (\>=60 bpm to \<=100 bpm), High (\>100 bpm); Temperature:- Low (\<=35 C), Normal (\>35 C and \<38 C), High (\>=38 C); Systolic Blood Pressure:- Low (\<90 mmHg), Normal (\>=90 mmHg to \<120 mmHg), High (\>=120 mmHg); Diastolic Blood Pressure:- Low (\<60 mmHg), Normal (\>=60 mmHg to \<80 mmHg), High (\>=80 mmHg). Participants were counted in the maximum worst case increase category that their value changes to (low, normal or high), unless there is no change in their category. Participants whose value category was unchanged (e.g., High to High), or whose value became normal, are recorded in the "To Normal or No Change" category. Participants were counted twice if the participants have values that changed 'To Low' and 'To High', so the percentages may not add to 100%.