A Study of Nivolumab Plus Brentuximab Vedotin in Patients Between 5 and 30 Years Old, With Hodgkin's Lymphoma (cHL), Relapsed or Refractory From First Line Treatment

Overall Response Rate (ORR) Following 4 Cycles of Nivolumab + Brentuximab Vedotin Treatment by Blinded Independent Centralized Review (BICR)

Overall response rate (ORR) is defined as the percent of all response-evaluable participants who, assessed by the BICR, achieved a best response of complete metabolic response (CMR) or partial metabolic response (PMR). Complete metabolic response (CMR): * Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale * New lesions: No * Bone marrow: No FDG-avid disease Partial metabolic response (PMR): * Lymph nodes/extralymphatic: Score 4 or 5, reduced uptake from baseline * New lesions: None * Bone marrow: Residual uptake higher than normal, reduced from baseline. Participants who came off early for toxicity without CMR or PMR were evaluable.

Time frame: From first dose to PMR or CMR within 4 cycles of therapy, or the completion of four cycles of therapy (N+Bv x4) (up to approximately 12 weeks).

Progression Free Survival (PFS) Rate at 3 Years by Blinded Independent Centralized Review (BICR)

Progression Free Survival (PFS) is the time from the date of first treatment to the date of first documented disease progression by BICR or death. Progressive Disease (PD): Lymph Nodes and Lesions: new growth or increase of \>= 50% in size from nadir. New or growing lesions outside the lymph nodes. Spleen: Significant increase in spleen size, either from a previously enlarged state or from normal size. New Lesions: Yes Bone Marrow: New or returning FDG-avid disease. Participants who neither progressed nor died were censored at the last adequate tumor assessment. Participants who started subsequent anticancer therapy (that is not part of high dose chemotherapy followed by autologous stem cell transplant (HDCT/ASCT) Consolidation Therapy for R2 Cohort) without a prior reported progression or death were censored at the last tumor assessment prior to initiation of the subsequent anticancer therapy. Based on Kaplan-Meier Estimates.

Time frame: At 3 years post first dose of study therapy

Duration of Response (DOR) by Blinded Independent Centralized Review (BICR)

Duration of response (DOR) is the time from first complete metabolic response or partial metabolic response (CMR or PMR) to event free survival EFS (Cohort 1)/progression free survival PFS (Cohort 2) event. For participants with no event, DOR was censored on the date of last tumor assessment. Participants who started subsequent anticancer therapy (not part of high-dose chemotherapy followed by autologous stem cell transplant HDCT/ASCT) without a prior reported EFS/PFS event were censored at the last tumor assessment prior to initiation of the subsequent therapy. Complete metabolic response (CMR): * Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale * New lesions: No * Bone marrow: No FDG-avid disease Partial metabolic response (PMR): * Lymph nodes/extralymphatic: Score 4 or 5, reduced uptake from baseline * New lesions: None * Bone marrow: Residual uptake higher than normal, reduced from baseline. Based on Kaplan-Meier estimates

Time frame: From first dose until disease progression, start of subsequent anti-cancer therapy, or or death due to any cause (up to approximately 86 months)

Complete Metabolic Response (CMR) Rate at Any Time Prior to Radiation Therapy by Investigator - Cohort 1

The complete metabolic response (CMR) rate is defined as the percent of all response-evaluable participants who, assessed by the investigator, achieved best response of CMR. Complete metabolic response (CMR): * Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale * New lesions: No * Bone marrow: No FDG-avid disease Participants who come off early for toxicity without a CMR were evaluable. Confidence interval is based on the Clopper and Pearson method

Time frame: From first dose to complete metabolic response or the completion of six cycles of therapy (up to approximately 18 weeks).

Event-free Survival (EFS) Rate at 3 Years by Investigator - Cohort 1

Event Free Survival (EFS) is the time from the first treatment to the earliest occurrence of composite events including: Disease progression (PD), Failure to achieve complete metabolic response (CMR) after 4 cycles of N+Bv and 2 cycles of Bv+B, Secondary malignancy, Death . PD : Lymph Nodes and Lesions: new growth or increase of \>= 50% in size from nadir. New or growing lesions outside the lymph nodes. Spleen: Significant increase in spleen size, either from a previously enlarged state or from normal size. New Lesions: Yes Bone Marrow: New or returning FDG-avid disease CMR: Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale New lesions: No Bone marrow: No FDG-avid disease Participants without an "event" were censored at the last tumor assessment. Those who started subsequent anticancer therapy without a prior "event" were censored at the last tumor assessment prior to or upon starting subsequent therapy. Based on Kaplan-Meier Estimates.

Time frame: At 3 years post first dose of study therapy

Complete Metabolic Response (CMR) Rate at Any Time Prior to High Dose Chemotherapy Followed by Autologous Stem Cell Treatment (HDCT/ASCT) by Investigator - Cohort 2

The complete metabolic response (CMR) rate is defined as the percent of all response-evaluable participants who, assessed by the investigator, achieved best response of CMR. Complete metabolic response (CMR): * Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale * New lesions: No * Bone marrow: No FDG-avid disease Participants who came off study treatment early for toxicity without a CMR were evaluable. Confidence interval is based on the Clopper and Pearson method.

Time frame: From first dose to complete metabolic response or the completion of six cycles of therapy (up to approximately 18 weeks)

Overall Response Rate (ORR) Following 4 Cycles of Nivolumab + Brentuximab Vedotin Treatment by Investigator

Overall response rate (ORR) is defined as the percent of all response-evaluable participants who, assessed by the investigator, achieve a best response of complete metabolic response (CMR) or partial metabolic response (PMR). Complete metabolic response (CMR): * Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale * New lesions: No * Bone marrow: No FDG-avid disease Partial metabolic response: * Lymph nodes/extralymphatic: Score 4 or 5, reduced uptake from baseline * New lesions: None * Bone marrow: Residual uptake higher than normal, reduced from baseline Participants who came off early for toxicity without CMR or PMR were evaluable.

Time frame: From first dose to PMR or CMR within 4 cycles of therapy, or the completion of four cycles of therapy (N+Bv x4) (up to approximately 12 weeks).

Progression Free Survival (PFS) Rate at 3 Years by Investigator

Progression Free Survival (PFS) is the time from the date of first treatment to the date of first documented disease progression by investigator or death. Progressive Disease (PD): Lymph Nodes and Lesions: new growth or increase of \>= 50% in size from nadir. New or growing lesions outside the lymph nodes. Spleen: Significant increase in spleen size, either from a previously enlarged state or from normal size. New Lesions: Yes Bone Marrow: New or returning FDG-avid disease. Participants who neither progressed nor died were be censored at the last adequate tumor assessment. Participants who started subsequent anticancer therapy (that is not part of high dose chemotherapy followed by autologous stem cell transplant (HDCT/ASCT) Consolidation Therapy forR2 Cohort) without a prior reported progression or death were censored at the last tumor assessment prior to initiation of the subsequent anticancer therapy. Based on Kaplan-Meier Estimates.

Time frame: At 3 years post first dose

Duration of Response (DOR) by Investigator

Duration of response (DOR) is the time from first complete metabolic response or partial metabolic response (CMR or PMR) to event free survival EFS (Cohort 1)/progression free survival PFS (Cohort 2) event. For participants with no event, the DOR was censored on the date of last tumor assessment. Participants who started subsequent anticancer therapy (not part of high-dose chemotherapy followed by autologous stem cell transplant HDCT/ASCT) without a prior reported EFS/PFS event were censored at the last tumor assessment prior to initiation of the subsequent anticancer therapy. Complete metabolic response (CMR): * Lymph nodes/extralymphatic sites: Score 1, 2, 3 with/without residual mass on 5-point scale * New lesions: No * Bone marrow: No FDG-avid disease Partial metabolic response: * Lymph nodes/extralymphatic: Score 4 or 5, reduced uptake from baseline * New lesions: None * Bone marrow: Residual uptake higher than normal, reduced from baseline. Based on Kaplan-Meier estimates.

Time frame: From first dose until disease progression, start of subsequent anti-cancer therapy, or or death due to any cause (up to approximately 86 months)

The Number of Participants With Adverse Events (AEs)

An Adverse Event (AE) is defined as any new untoward medical occurrence or worsening of a preexisting medical condition in a clinical investigation participant administered study drug and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (such as an abnormal laboratory finding), symptom, or disease temporally associated with the use of study drug, whether or not considered related to the study drug.

Time frame: From first dose to 30 days post last dose (an average of 4 months up until a maximum of 7 months).

The Number of Participants With Serious Adverse Events (SAEs)

A Serious Adverse Event (SAE) is defined as any untoward medical occurrence that, at any dose: * Results in death * Is life-threatening (defined as an event in which the participant was at risk of death at the time of the event; it does not refer to an event which hypothetically might have caused death if it were more severe) * Requires inpatient hospitalization or causes prolongation of existing hospitalization * Results in persistent or significant disability/incapacity * Is a congenital anomaly/birth defect * Is an important medical event.

Time frame: From first dose to 30 days post last dose (an average of 4 months up until a maximum of 7 months)

The Number of Participants With Abnormal Laboratory Values for Specific Thyroid Tests

The Number of Participants with Abnormal Laboratory Values for Specific Thyroid Tests.

Time frame: From first dose to 30 days post last dose (an average of 4 months up until a maximum of 7 months)

The Number of Participants With Abnormal Laboratory Values for Liver Tests

The Number of Participants with Abnormal Laboratory Values for Liver Tests.

Time frame: From first dose to 30 days post last dose (an average of 4 months up until a maximum of 7 months)

Number of Participants With Abnormal Vital Signs Reported as Adverse Events

Temperature, blood pressure, and heart rate abnormalities reported as adverse events.

Time frame: From first dose to 100 days after last dose of study therapy (assessed for an average of 7 months up until a maximum of 10 months).