MUNICH – In patients with recurrent or metastatic head and neck squamous cell carcinoma expressing programmed death ligand-1 (PDL-1), the immune checkpoint inhibitor pembrolizumab alone or in combination with chemotherapy improved overall survival, compared with the EXTREME chemotherapy regimen, reported investigators in the Keynote 048 trial.
Overall survival (OS) among patients with a PD-L1 combined positive score (CPS) of 20 or greater treated with pembrolizumab (Keytruda) monotherapy was 14.9 months compared with 10.7 months for patients treated with the EXTREME regimen, a combination of cetuximab (Erbitux), carboplatin or cisplatin, and 5-fluorouracil.
A similar overall survival benefit was seen in patients with a CPS of 1 or greater, and in the total population of patients treated with pembrolizumab plus chemotherapy followed by pembrolizumab maintenance compared with EXTREME chemotherapy, Barbara Burtness, MD, of Yale Cancer Center, New Haven, Conn.
There were no differences in response rates between either pembrolizumab monotherapy or in combination compared with chemotherapy alone, but responses were more durable with the checkpoint inhibitor than with chemotherapy.
“Pembrolizumab alone and pembrolizumab given with platinum and 5-fluorouracil should represent new standards of care for the first-line treatment of metastatic head and neck carcinoma. Immune checkpoint monotherapy with pembrolizumab allows patients to live longer and has a better safety profile than the previous standard for those patients whose tumors express PD-L1,” she said at a briefing prior to her presentation of the data in a presidential symposium at the European Society for Medical Oncology Congress.
“This is the first time since 10 years that we show an improvement in survival for this group of patients,” said Jean-Pascal Machiels, MD, of University Clinic Saint-Luc, Brussels, the invited discussant for the briefing and the symposium.
The CPS is a ratio of PD-L1-positive tumor cells, lymphocytes, and macrophages to the total numbers of cells counted multiplied by 100. The investigators looked at progression-free survival (PFS) and OS in three cohorts of patients with squamous cell carcinomas of the oropharynx, oral cavity, hypopharynx, or larynx that were recurrent or metastatic and were incurable by local therapies. They compared pembrolizumab monotherapy with the EXTREME regimen, and pembrolizumab plus chemotherapy (as described in the following paragraph) with EXTREME.
A total of 882 patients were enrolled and stratified by PD-L1 expression (on 50% or greater of tumor cells, or less than 50%), p16 positive or negative status in the oropharynx, and Eastern Cooperative Oncology Group performance status of 0 or 1. The patients were then randomly assigned on a 1:1:1 basis to either pembrolizumab monotherapy at 200 mg every 3 weeks for up to 35 cycles, pembrolizumab plus a standard chemotherapy regimen (carboplatin to an area-under-the curve [AUC] of 5 or cisplatin 100 mg/m2 plus 5-FU 1000 mg/m2 per day for 4 days for six cycles, followed by pembrolizumab maintenance for up to 35 cycles or EXTREME (cetuximab at a loading dose of 400 mg/m2 followed by 250 mg/m2 once weekly plus the chemotherapy regimen described above, followed by maintenance cetuximab).