PRISM (Panitumumab Regimen In Second-line Monotherapy of Head and Neck Cancer)

Assessments are based on investigator's review of scans using a modified Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0. Objective response rate was defined as the percentage of participants with a best tumor response of complete response (CR) or partial response (PR) prior to initiation of subsequent anti-cancer therapy. CR or PR was confirmed no less than 28 days after the criteria for response were first met. CR: Disappearance of all target lesions, non-target lesions and no new lesions. PR: At least a 30% decrease in the size of target lesions and no progression of existing non-target lesions (defined as an increase in lesion size of ≥ 20%) and no new lesions, or, the disappearance of all target lesions and the persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease (PD) and no new lesions.

Time to response was defined as the time from Study Day 1 to the first CR or PR that was subsequently confirmed.

Duration of response was defined as the time from first confirmed CR or PR to the earliest date of disease progression per a modified version of the RECIST criteria (version 1.0). Participants not meeting the criteria for progression by the analysis data cut-off date were censored at the date of last evaluable disease assessment. Duration of response was analyzed using the Kaplan-Meier method.

PD: At least a 20% increase in the size of target lesions, or an increase of 20% or greater of non-target lesions and the lesion(s) measure ≥ 10 mm in one dimension at the time of progression, or any new lesions.

Rate of disease control was defined as the percentage of participants with CR, PR, or stable disease (SD), as defined by a modified version of the RECIST criteria (version 1.0), prior to initiation of subsequent anti-cancer therapy.

SD: Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD of target lesions and no progression of non-target lesions and no new lesions, or, if no target lesions were identified at screening, the persistence of one or more non-target lesion(s) not qualifying for either CR or PD.

Time to progression was defined as the time from Day 1 to the date of disease progression using a modified version of the RECIST criteria (version 1.0). Participants not meeting the criteria for progression by the analysis data cut-off date were censored at the date of last evaluable disease assessment. Time to progression was analyzed using the Kaplan-Meier method.

PFS was defined as the time from Day 1 to the first date of disease progression, as defined by a modified version of the RECIST criteria (version 1.0), or death due to any cause (whichever comes first). Participants who were alive who did not meet the criteria for progression by the analysis data cut-off date were censored at the date of last evaluable disease assessment.

PFS was analyzed using the Kaplan-Meier method.

Overall Survival was defined as the time from Day 1 to the date of death. For participants who did not die while on study, or were lost to follow-up, survival was censored at the end of study, or the date of last contact (whichever was first).

The severity of each adverse event (AE) was graded using the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 (where grade 1=mild, grade 2=moderate, grade 3=severe, grade 4=life-threatening and grade 5=fatal) with the exception of some dermatology/skin AEs that were graded using the CTCAE v3.0 with modifications. Serious AEs include any event that was fatal, life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, a congenital anomaly/birth defect, or other significant medical hazard. Treatment-related adverse events (TRAEs) are those for which the investigator considered there to be a reasonable possibility that the event may have been caused by study drug.