Trial of Nivolumab vs Therapy of Investigator's Choice in Recurrent or Metastatic Head and Neck Carcinoma (CheckMate 141)

OS was defined as the time from randomization to the date of death from any cause. Participants were censored at the date they were last known to be alive and at the date of randomization if they were randomized but had no follow-up. Median OS time was calculated using Kaplan-Meier (KM) method.

PFS was defined as the time between the date of randomization and the first date of documented progression, as determined by the investigator (as per Response Evaluation Criteria In Solid Tumors (RECIST1.1)), or death due to any cause, whichever occurs first. Progressive Disease: at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. The sum must demonstrate an absolute increase of at least 5mm. Participants who:

• Die without a reported progression were considered to have progressed on the date of their death.
• Did not progress or die were censored on the date of their last evaluable tumor assessment.
• Without any on study tumor assessments and did not die were censored on their date of randomization.
• Received subsequent systemic anti-cancer therapy prior to documented progression were censored at the date of the last tumor assessment prior to the initiation of the new therapy.

ORR was defined as the percentage of randomized participants who achieved a best response of complete response (CR) or partial response (PR) using the RECIST1.1 criteria as per investigator assessment. Complete Response (CR): Disappearance of all target lesions. Partial Response (PR): At least a 30% decrease in the sum of diameters of target lesions.