Hsu C, et al. - In patients with recurrent or metastatic nasopharyngeal carcinoma (RM-NPC) that expressed programmed death-ligand 1 (PD-L1), the safety profile and antitumor activity of the anti-programmed death 1 receptor monoclonal antibody, pembrolizumab, was explored. Here, pembrolizumab demonstrated antitumor activity and a manageable safety profile in these patients.

Methods

• Researchers performed a nonrandomized, multicohort, phase Ib trial (KEYNOTE-028 study) of pembrolizumab in patients with PD-L1–positive advanced solid tumors.
• For the NPC cohort, key eligibility criteria included unresectable or metastatic disease, failure on prior standard therapy, and PD-L1 expression in 1% or more of tumor cells or tumor-infiltrating lymphocytes.
• They administered pembrolizumab 10 mg/kg to patients every 2 weeks up to 2 years or until disease progression or unacceptable toxicity.
• Objective response rate (ORR) per investigator review was assessed as the primary end point.
• In accordance to Response Evaluation Criteria in Solid Tumors (RECIST; version 1.1), tumor response was assessed every 8 weeks for the first 6 months and every 12 weeks thereafter.

Results

• Pembrolizumab was administered to 27 patients.
• Data revealed that median age of patients was 52.0 years (range, 18 to 68 years); 92.6% received prior therapies for RM-NPC; 70.4% had received 3 or more therapies.
• Over a median follow-up of 20 months, 7 and 14 patients indicated partial response and stable disease, respectively, for an ORR of 25.9% (95% CI, 11.1 to 46.3).
• Similar (26.3%) ORR was revealed by central review.
• In 15% or more of patients, drug-related adverse events occurred, these included rash (25.9%), pruritus (25.9%), pain (22.2%), hypothyroidism (18.5%), and fatigue (18.5%).
• Eight patients (29.6%) experienced grade ≥ 3 drug-related adverse events, and there was one drug-related death (sepsis).
• Two patients remained on pembrolizumab treatment as of the data cutoff (June 20, 2016).