ORR is the percentage of participants who had a CR or PR prior to disease progression assessed by the investigator using IWG criteria. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The point estimate and 95% 2-sided exact confidence interval (CI) used the Clopper-Pearson method. An exact binomial test was conducted for each cohort versus a fixed control rate for each cohort.

CRR is the percentage of participants with complete remission as demonstrated by disappearance of all evidence of disease in the bone marrow, spleen, liver, and lymph nodes based on the IWG criteria using BICR. The analysis consisted of the point estimate and 95% 2-sided exact CI, separately by Cohort using the Clopper-Pearson method. Additional analyses were based on site assessment and by central review using the Lugano (2014) criteria.

CRR is the percentage of participants with complete remission as demonstrated by disappearance of all evidence of disease in the bone marrow, spleen, liver, and lymph nodes based on the Lugano criteria using BICR. The analysis consisted of the point estimate and 95% 2-sided exact CI, separately by Cohort using the Clopper-Pearson method. Additional analyses were based on site assessment and by central review using the Lugano (2014) criteria.

CRR is the percentage of participants with complete remission as demonstrated by disappearance of all evidence of disease in the bone marrow, spleen, liver, and lymph nodes assessed by the investigator using IWG criteria. The analysis consisted of the point estimate and 95% 2-sided exact CI, separately by Cohort using the Clopper-Pearson method. Additional analyses were based on site assessment and by central review using the Lugano (2014) criteria.

PFS is the time from first dose to the first documented progressive disease (PD) or death due to any cause, whichever occurs first based on BICR. For those who have PD, the true date of disease progression was approximated by the date of the first assessment at which PD is objectively documented per IWG criteria, regardless of discontinuation of study drug. Death is always considered as a confirmed PD event. The non-parametric Kaplan-Meier method was used to estimate the PFS curve with missing data censored at last assessment.

PFS is the time from first dose to the first documented progressive disease (PD) or death due to any cause, whichever occurs first assessed by the investigator based on the IWG criteria. For those who have PD, the true date of disease progression was approximated by the date of the first assessment at which PD is objectively documented per IWG criteria, regardless of discontinuation of study drug. Death is always considered as a confirmed PD event. The non-parametric Kaplan-Meier method was used to estimate the PFS curve with missing data censored at last assessment.

DOR for the subgroup of participants who achieved a CR or PR by independent central review, is the time from start of the first documentation of objective tumor response (CR or PR) to the first documentation of PD or to death due to any cause, whichever comes first based on BICR. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The analysis used the Kaplan-Meier method, with participants with response censored at their last assessment, and there was no progressive disease at the time of the last disease assessment.

DOR for the subgroup of participants who achieved a CR or PR by independent central review, is the time from start of the first documentation of objective tumor response (CR or PR) to the first documentation of PD or to death due to any cause, whichever comes first assessed by the investigator based on the IWG criteria. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The analysis used the Kaplan-Meier method, with participants with response censored at their last assessment, and there was no progressive disease at the time of the last disease assessment.

OS is the time from the first dose to death due to any cause. The Kaplan-Meier method was used to estimate the survival curve, separately by Cohort with missing data censored at last assessment.

Participants with RRcHL who failed to achieve a response to or progressed after auto-SCT and have not received BV post auto-SCT received pembrolizumab, 200 mg, IV Q3W on Day 1 of each 21-day cycle, up to 35 cycles for up to 24 months. These participants may or may not have received BV as part of primary treatment or salvage treatment.

Total of all reporting groups

Participants with RRcHL who were unable to achieve Complete Response (CR) or Partial Response (PR) to salvage chemotherapy and did not receive auto-SCT, but have relapsed after treatment with or failed to respond to BV received pembrolizumab, 200 mg, IV Q3W on Day 1 of each 21-day cycle up to 35 cycles, for up to 24 months.

Participants with RRcHL who failed to achieve a response to or progressed after auto-SCT and have not received BV post auto-SCT received pembrolizumab, 200 mg, IV Q3W on Day 1 of each 21-day cycle, up to 35 cycles for up to 24 months. These participants may or may not have received BV as part of primary treatment or salvage treatment.

An adverse event (AE) is any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it is considered related to the medical treatment or procedure, that occurs during the course of the study

All allocated participants who received at least 1 dose of study treatment.

An AE is any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it is considered related to the medical treatment or procedure, that occurs during the course of the study

All allocated participants who received at least 1 dose of study treatment

ORR is the percentage of participants who had a CR or PR prior to disease progression based on the Lugano criteria using BICR. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The point estimate and 95% 2-sided exact confidence interval (CI) used the Clopper-Pearson method. An exact binomial test was conducted for each cohort versus a fixed control rate for each cohort.

All allocated participants who received at least 1 dose of study treatment.

ORR is the percentage of participants who had a CR or PR prior to disease progression assessed by the investigator using IWG criteria. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The point estimate and 95% 2-sided exact confidence interval (CI) used the Clopper-Pearson method. An exact binomial test was conducted for each cohort versus a fixed control rate for each cohort.

All allocated participants who received at least 1 dose of study treatment.

CRR is the percentage of participants with complete remission as demonstrated by disappearance of all evidence of disease in the bone marrow, spleen, liver, and lymph nodes based on the IWG criteria using BICR. The analysis consisted of the point estimate and 95% 2-sided exact CI, separately by Cohort using the Clopper-Pearson method. Additional analyses were based on site assessment and by central review using the Lugano (2014) criteria.

All allocated participants who received at least 1 dose of study treatment.

CRR is the percentage of participants with complete remission as demonstrated by disappearance of all evidence of disease in the bone marrow, spleen, liver, and lymph nodes based on the Lugano criteria using BICR. The analysis consisted of the point estimate and 95% 2-sided exact CI, separately by Cohort using the Clopper-Pearson method. Additional analyses were based on site assessment and by central review using the Lugano (2014) criteria.

All allocated participants who received at least 1 dose of study treatment.

CRR is the percentage of participants with complete remission as demonstrated by disappearance of all evidence of disease in the bone marrow, spleen, liver, and lymph nodes assessed by the investigator using IWG criteria. The analysis consisted of the point estimate and 95% 2-sided exact CI, separately by Cohort using the Clopper-Pearson method. Additional analyses were based on site assessment and by central review using the Lugano (2014) criteria.

All allocated participants who received at least 1 dose of study treatment.

PFS is the time from first dose to the first documented progressive disease (PD) or death due to any cause, whichever occurs first based on BICR. For those who have PD, the true date of disease progression was approximated by the date of the first assessment at which PD is objectively documented per IWG criteria, regardless of discontinuation of study drug. Death is always considered as a confirmed PD event. The non-parametric Kaplan-Meier method was used to estimate the PFS curve with missing data censored at last assessment.

All allocated participants who received at least 1 dose of study treatment.

PFS is the time from first dose to the first documented progressive disease (PD) or death due to any cause, whichever occurs first assessed by the investigator based on the IWG criteria. For those who have PD, the true date of disease progression was approximated by the date of the first assessment at which PD is objectively documented per IWG criteria, regardless of discontinuation of study drug. Death is always considered as a confirmed PD event. The non-parametric Kaplan-Meier method was used to estimate the PFS curve with missing data censored at last assessment.

All allocated participants who received at least 1 dose of study treatment.

DOR for the subgroup of participants who achieved a CR or PR by independent central review, is the time from start of the first documentation of objective tumor response (CR or PR) to the first documentation of PD or to death due to any cause, whichever comes first based on BICR. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The analysis used the Kaplan-Meier method, with participants with response censored at their last assessment, and there was no progressive disease at the time of the last disease assessment.

All allocated participants who received at least 1 dose of study treatment and had a CR or PR response.

DOR for the subgroup of participants who achieved a CR or PR by independent central review, is the time from start of the first documentation of objective tumor response (CR or PR) to the first documentation of PD or to death due to any cause, whichever comes first assessed by the investigator based on the IWG criteria. CR is the disappearance of all evidence of disease and PR is the regression of measurable disease and no new sites. The analysis used the Kaplan-Meier method, with participants with response censored at their last assessment, and there was no progressive disease at the time of the last disease assessment.

All allocated participants who received at least 1 dose of study treatment and had a CR or PR response.

OS is the time from the first dose to death due to any cause. The Kaplan-Meier method was used to estimate the survival curve, separately by Cohort with missing data censored at last assessment.

All allocated participants who received at least 1 dose of study treatment.

Participants with RRcHL who were unable to achieve Complete Response (CR) or Partial Response (PR) to salvage chemotherapy and did not receive auto-SCT, but have relapsed after treatment with or failed to respond to BV received pembrolizumab, 200 mg, IV Q3W on Day 1 of each 21-day cycle up to 35 cycles, for up to 24 months.

Participants with RRcHL who failed to achieve a response to or progressed after auto-SCT and have not received BV post auto-SCT received pembrolizumab, 200 mg, IV Q3W on Day 1 of each 21-day cycle up to 35 cycles, for up to 24 months. These participants may or may not have received BV as part of primary treatment or salvage treatment.

Eligible participants allocated to the pembrolizumab first course in Cohort 1 who stopped (or completed) initial treatment with pembrolizumab after attaining confirmed CR, initiated a second course of pembrolizumab at the investigator's discretion at 200 mg on Day 1 of each 3 week cycle (Q3W) for up to 17 cycles up to approximately an additional year.

Eligible participants allocated to the pembrolizumab first course in Cohort 2 who stopped (or completed) initial treatment with pembrolizumab after attaining confirmed CR, initiated a second course of pembrolizumab at the investigator's discretion at 200 mg on Day 1 Q3W for up to 17 cycles up to approximately an additional year.

Eligible participants allocated to the pembrolizumab first course in Cohort 3 who stopped (or completed) initial treatment with pembrolizumab after attaining confirmed CR, initiated a second course of pembrolizumab at the investigator's discretion at 200 mg on Day 1 Q3W for up to 17 cycles up to approximately an additional year.