A Study of Pembrolizumab in Japanese Pediatric Participants With Solid Tumors or Lymphomas and Japanese Adult Participants With Merkel Cell Carcinoma (MK-3475-G21/KEYNOTE-G21)

An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE can therefore be any unfavourable and unintended sign (including an abnormal laboratory finding, for example), symptom, or disease temporally associated with the use of a study intervention. The number of participants with solid tumors or lymphomas who experience an AE will be reported.

An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE can therefore be any unfavourable and unintended sign (including an abnormal laboratory finding, for example), symptom, or disease temporally associated with the use of a study intervention. The number of participants with solid tumors or lymphomas who discontinue study treatment due to an AE will be reported.

AUC is defined as the area under the concentration-time curve of pembrolizumab. Blood samples will be collected at specified intervals for the determination of AUC. AUC in participants with solid tumors or lymphomas will be reported.

Cmax is defined as the maximum concentration of pembrolizumab reached. Blood samples will be collected at pre-specified intervals for the determination of Cmax. Cmax in participants with solid tumors or lymphomas will be reported.

Cmin is defined as the minimum concentration of pembrolizumab observed in plasma after its administration and just prior to administration of a subsequent dose. Blood samples will be collected at pre-specified timepoints to determine Cmin. Cmin in participants with solid tumors or lymphomas will be reported.

ORR is defined as complete response (CR: disappearance of all target lesions) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1 as assessed by blinded independent central review (BICR). ORR in participants with Merkel cell carcinoma will be reported.

ORR is defined as complete response (CR: disappearance of all target lesions) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1 by investigator assessment. ORR in participants with solid tumors will be reported.

ORR is defined as complete response (CR: all target lymph nodes must have regressed to normal size defined as ≤1.5 cm in longest diameter) or partial response (PR: ≥50% decrease in sum of products of diameters of target lesions from baseline, and no individual lesion meets the criteria for progression), per Lugano classification (Cheson et al, Journal of Clinical Oncology, 2014). ORR in participants with lymphomas as assessed by investigator will be reported.

For participants who demonstrate a complete response (CR: disappearance of all target lesions) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR is defined as the time from first documented evidence of CR or PR until progressive disease (PD) or death. Per RECIST 1.1, PD is defined as at least a 20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered PD. DOR per RECIST 1.1 by investigator assessment in participants with solid tumors will be reported.

For participants who demonstrate confirmed CR or PR, DOR is defined as the time from the first documented evidence of CR (all target lymph nodes must have regressed to normal size defined as ≤1.5 cm in longest diameter) or PR (≥50% decrease in sum of products of diameters of target lesions from baseline, and no individual lesion meets the criteria for progression) per Lugano classification (Cheson et al, Journal of Clinical Oncology, 2014) until progressive disease (PD: based on the progression of any single lesion and other certain requirements) or death due to any cause, whichever occurs first. DOR in participants with lymphomas as assessed by investigator will be reported.

DCR is defined, per RECIST 1.1, as the percentage of participants who have a CR or PR or stable disease (SD: Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease [PD: At least a 20% increase in the sum of diameters of target lesions and an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered PD]). DCR per RECIST 1.1 by investigator assessment in participants with solid tumors will be reported.

DCR is defined as confirmed CR (all target lymph nodes must have regressed to normal size defined as ≤1.5 cm in longest diameter), PR (≥50% decrease in sum of products of diameters of target lesions from baseline, and no individual lesion meets the criteria for progression), or stable disease (SD: Target lesions do not meet the criteria for CR or PR and no individual lesion meets the criteria for progression) per Lugano classification (Cheson et al, Journal of Clinical Oncology, 2014). DCR in participants with lymphomas as assessed by investigator will be reported.

PFS is defined as the time from randomization to the first documented progressive disease (PD) or death due to any cause, whichever occurs first as assessed by RECIST 1.1. PD is defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. The appearance of one or more new lesions is also considered PD. PFS per RECIST 1.1 by investigator assessment in participants with solid tumors will be reported.

PFS is defined as the time from randomization to the first documented progressive disease (PD) or death due to any cause, whichever occurs first as assessed by Lugano classification (Cheson et al, Journal of Clinical Oncology, 2014) by investigator. PD per Lugano classification is defined as based on the progression of any single lesion and other certain requirements. PFS in participants with solid tumors will be reported.

RFS is defined only for adjuvant melanoma participants as the time from first dose to recurrence of melanoma at any site (local, in-transit or regional lymph nodes or distant recurrence) per RECIST 1.1 by investigator assessment or death due to any cause, whichever occurs first. New incident cases of melanoma and second cancer diagnoses are not counted as events for recurrence-free survival. RFS in participants with solid tumors or lymphomas will be reported.

DMFS is defined only for adjuvant melanoma participants as the time from first dosing to the first diagnosis of a distant metastasis per RECIST 1.1 by investigator assessment or death (due to any cause), whichever occurs first. Distant metastasis refers to cancer that has spread from the original (primary) tumor and beyond local tissues and lymph nodes to distant organs or distant lymph nodes. DMFS in participants with solid tumors or lymphomas will be reported.

OS is defined as the time from the first dose of study intervention to death due to any cause. OS in participants with solid tumors or lymphomas will be reported.

Blood samples will be collected at multiple time points to determine the ADA response to pembrolizumab. The number of participants with ADA for pembrolizumab in participants with solid tumors or lymphomas will be reported.

ORR is defined as complete response (CR: disappearance of all target lesions) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1 by investigator assessment. ORR in participants with Merkel cell carcinoma will be reported.

For participants who demonstrate a complete response (CR: disappearance of all target lesions) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR is defined as the time from first documented evidence of CR or PR until progressive disease (PD) or death. Per RECIST 1.1, PD is defined as at least a 20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered PD. DOR per RECIST 1.1 by BICR in participants with Merkel cell carcinoma will be reported.

For participants who demonstrate a confirmed CR: disappearance of all target lesions or PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR is defined as the time from first documented evidence of CR or PR until progressive disease (PD) or death. Per RECIST 1.1, PD is defined as at least a 20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered PD. DOR by investigator assessment in participants with Merkel cell carcinoma will be reported.

DCR is defined, per RECIST 1.1, as the percentage of participants who have a CR or PR or stable disease (SD: Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease [PD: At least a 20% increase in the sum of diameters of target lesions and an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered PD]). DCR per RECIST 1.1 by BICR in participants with Merkel cell carcinoma will be reported.

DCR is defined, per RECIST 1.1, as the percentage of participants who have a CR or PR or stable disease (SD: Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD: At least a 20% increase in the sum of diameters of target lesions and an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered PD). DCR per RECIST 1.1 by investigator assessment in participants with Merkel cell carcinoma will be reported.

PFS is defined as the time from randomization to the first documented progressive disease (PD) or death due to any cause, whichever occurs first as assessed by RECIST 1.1. PD is defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. The appearance of one or more new lesions is also considered PD. PFS per RECIST 1.1 by BICR in participants with Merkel cell carcinoma will be reported.

PFS is defined as the time from randomization to the first documented progressive disease (PD) or death due to any cause, whichever occurs first as assessed by RECIST 1.1. PD is defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. The appearance of one or more new lesions is also considered PD. PFS per RECIST 1.1 by investigator assessment in participants with Merkel cell carcinoma will be reported.

OS is defined as the time from the first dose of study intervention to death due to any cause. OS in participants with Merkel cell carcinoma will be reported.

Cmax is defined as the maximum concentration of pembrolizumab reached. Blood samples will be collected at pre-specified intervals for the determination of Cmax. Cmax in participants with Merkel cell carcinoma will be reported.

Cmin is defined as the minimum concentration of pembrolizumab observed in plasma after its administration and just prior to administration of a subsequent dose. Blood samples will be collected at pre-specified timepoints to determine Cmin. Cmin in participants with Merkel cell carcinoma will be reported.

An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE can therefore be any unfavourable and unintended sign (including an abnormal laboratory finding, for example), symptom, or disease temporally associated with the use of a study intervention. The number of participants with Merkel cell carcinoma who experience an AE will be reported.

An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE can therefore be any unfavourable and unintended sign (including an abnormal laboratory finding, for example), symptom, or disease temporally associated with the use of a study intervention. The number of participants with Merkel cell carcinoma who discontinue study treatment due to an AE will be reported.