Study of MK-3475 (Pembrolizumab) in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma After Treatment With Platinum-based and Cetuximab Therapy (MK-3475-055/KEYNOTE-055)

ORR was assessed by RECIST 1.1 by performing imaging every 6-9 weeks after the first dose of treatment. ORR was defined as the percentage of participants in the analysis population who had a Complete Response (CR) defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or Partial Response (PR) defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. Participants with missing data were considered non-responders.

Participants with a strong PD-L1 expression status were evaluated for ORR by RECIST 1.1. The expression of PD-L1 was determined by immunohistochemistry (IHC) and strong PD-L1 positive was defined as a PD-L1 tumor proportion score ≥50%. ORR was assessed by performing imaging every 6-9 weeks after the first dose of treatment. ORR was defined as the percentage of participants in the analysis population who had a CR defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or PR defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. Participants with missing data were considered non-responders.

An AE was defined as any untoward medical occurrence in a participant administered a pharmaceutical product and which did not necessarily have to have a causal relationship with treatment. An AE could therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of the product, whether or not considered related to the product. Worsening of a preexisting condition temporally associated with the use of the product was also an AE. A serious adverse event (SAE) was an AE that resulted in death, was life threatening, resulted in persistent or significant disability/incapacity, resulted in or prolonged an existing inpatient hospitalization, was a congenital anomaly/birth defect, was a cancer, was associated with an overdose, or was another important medical event. Per protocol, analysis for this outcome measure was planned to be performed during the initial (first) course of therapy only.

An AE was defined as any untoward medical occurrence in a participant administered a pharmaceutical product and which did not necessarily have to have a causal relationship with treatment. An AE could therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of the product, whether or not considered related to the product. Worsening of a preexisting condition temporally associated with the use of the product was also an AE. A serious adverse event (SAE) was an AE that resulted in death, was life threatening, resulted in persistent or significant disability/incapacity, resulted in or prolonged an existing inpatient hospitalization, was a congenital anomaly/birth defect, was a cancer, was associated with an overdose, or was another important medical event. Per protocol, analysis for this outcome measure was planned to be performed during the initial (first) course of therapy only.

Participants with a positive PD-L1 expression status were evaluated for ORR by RECIST 1.1. PD-L1 expression was determined by IHC and PD-L1 positive was defined as a PD-L1 tumor proportion score ≥1%. ORR was assessed by performing imaging every 6-9 weeks after the first dose of treatment. ORR was defined as the percentage of participants in the analysis population who had a CR defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or PR defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. Participants with missing data were considered non-responders.

Participants with a HPV-positive tumor biopsy were evaluated for ORR by RECIST 1.1. ORR was assessed by performing imaging every 6-9 weeks after the first dose of treatment. ORR was defined as the percentage of participants in the analysis population who had a CR defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or PR defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. Participants with missing data were considered non-responders.

ORR was assessed by modified RECIST 1.1 by performing imaging every 6-9 weeks after the first dose of treatment. ORR was defined as the percentage of participants in the analysis population who had a CR defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or PR defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. If imaging shows disease progression (PD) imaging was repeated 4 weeks later to confirm progression. PD was defined as at least a 20% increase in the sum of diameters of target lesions and new measurable lesions, taking as reference the smallest sum recorded since treatment started. Participants with missing data were considered non-responders.

Participants with a positive PD-L1 expression status were evaluated for ORR by modified RECIST 1.1. PD-L1 expression was determined by IHC and PD-L1 positive was defined as a tumor proportion score ≥1%. ORR was assessed by performing imaging every 6-9 weeks after the first dose of treatment. ORR was defined as the percentage of participants in the analysis population who had a CR defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or PR defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. If imaging shows disease progression (PD) imaging was repeated 4 weeks later to confirm progression. PD was defined as at least a 20% increase in the sum of diameters of target lesions and new measurable lesions, taking as reference the smallest sum recorded since treatment started. Participants with missing data were considered non-responders.

Participants with a strong positive PD-L1 expression status were evaluated for ORR by modified RECIST 1.1. PD-L1 expression was determined by IHC and strong PD-L1 positive was defined as a tumor proportion score ≥50%. ORR was defined as the percentage of participants in the analysis population who had a CR defined as a disappearance of all target lesions with pathological lymph nodes having a reduction in short axis to <10 mm or PR defined as at least a 30% decrease in the sum of diameters of target lesions, using the baseline sum diameters as a reference. If imaging shows disease progression (PD) imaging was repeated 4 weeks later to confirm progression. PD was defined as at least a 20% increase in the sum of diameters of target lesions and new measurable lesions, taking as reference the smallest sum recorded since treatment started. Participants with missing data were considered non-responders.

DOR was based on RECIST 1.1 and measured from the time measurement criteria were first met for CR/PR (whichever was first recorded) until the first date that recurrent or PD was objectively documented (taking as reference for PD the smallest measurements recorded on study). DOR was censored at the last tumor assessment date if a responder did not have PD or death. Non-responders were not included in the analysis. The lower and upper limits were estimated at the time of data cutoff. DOR was analyzed by the Kaplan-Meier method for censored data and reported in months.

Participants with a positive PD-L1 expression status were evaluated for DOR based on RECIST 1.1. PD-L1 expression was determined by IHC and PD-L1 positive was defined as a PD-L1 combined positive score ≥1%. DOR was measured from the time measurement criteria were first met for CR/PR (whichever was first recorded) until the first date that recurrent or PD was objectively documented (taking as reference for PD the smallest measurements recorded on study). DOR was censored at the last tumor assessment date if a responder did not have PD or death. Non-responders were not included in the analysis. The lower and upper limits were estimated at the time of data cutoff. DOR was analyzed by the Kaplan-Meier method for censored data and reported in months.

Participants with a strong PD-L1 expression status were evaluated for DOR based n RECIST 1.1. PD-L1 expression was determined by IHC and strong PD-L1 positive was defined as a PD-L1 tumor proportion score ≥50%. DOR was measured from the time measurement criteria were first met for CR/PR (whichever was first recorded) until the first date that recurrent or PD was objectively documented (taking as reference for PD the smallest measurements recorded on study). DOR was censored at the last tumor assessment date if a responder did not have PD or death. Non-responders were not included in the analysis. The lower and upper limits were estimated at the time of data cutoff. DOR was analyzed by the Kaplan-Meier method for censored data and reported in months.

PFS was defined as the time from the first day of study treatment to the first documented PD per RECIST 1.1 or death due to any cause, whichever occurred first. Using RECIST 1.1, PD was defined as either a 20% relative increase in the sum of diameters of target lesions, taking as reference the smallest sum on study OR an absolute increase of >5 mm the sum of lesions, OR the appearance of new lesions. PFS was analyzed by the Kaplan-Meier method for censored data and reported in months. Participant data were censored at last assessment.

Participants with a positive PD-L1 expression status were evaluated for PFS. PD-L1 expression was determined by IHC and PD-L1 positive was defined as a PD-L1 combined positive score ≥1%. PFS was defined as the time from the first day of study treatment to the first documented PD per RECIST 1.1 or death due to any cause, whichever occurred first. Using RECIST 1.1, PD was defined as either a 20% relative increase in the sum of diameters of target lesions, taking as reference the smallest sum on study OR an absolute increase of >5 mm the sum of lesions, OR the appearance of new lesions. PFS was analyzed by the Kaplan-Meier method for censored data and reported in months. Participant data were censored at last assessment.

Participants with a strong PD-L1 expression status were evaluated for PFS by modified RECIST 1.1. PD-L1 expression was determined by IHC and strong PD-L1 positive was defined as a PD-L1 tumor proportion score ≥50%. PFS was defined as the time from the first day of study treatment to the first documented PD per RECIST 1.1 or death due to any cause, whichever occurred first. Using RECIST 1.1, PD was defined as either a 20% relative increase in the sum of diameters of target lesions, taking as reference the smallest sum on study OR an absolute increase of >5 mm the sum of lesions, OR the appearance of new lesions. PFS was analyzed by the Kaplan-Meier method for censored data and reported in months. Participant data were censored at last assessment.

OS was defined as the time from the first day of study treatment to death due to any cause. OS was analyzed by the Kaplan-Meier method for censored data and reported in months. Participant data were censored at last assessment.

Participants with a positive PD-L1 expression status were evaluated for OS. PD-L1 expression was determined by IHC and PD-L1 positive was defined as a PD-L1 combined positive score ≥1%. OS was defined as the time from the first day of study treatment to death due to any cause. OS was analyzed by the Kaplan-Meier method for censored data and reported in months. Participant data were censored at last assessment.

Participants with a strong PD-L1 expression status were evaluated for OS. PD-L1 expression was determined by IHC and strong PD-L1 positive was defined as a PD-L1 tumor proportion score ≥50%. OS was defined as the time from the first day of study treatment to death due to any cause. OS was analyzed by the Kaplan-Meier method for censored data and reported in months. Participant data were censored at last assessment.