MSD’s Keytruda (pembrolizumab) made an impact at the European Society for Medical Oncology 2018 Congress as the company unveiled new Phase 3 data into its efficacy in the first-line treatment of recurrent or metastatic head and neck squamous cell carcinoma (HNSCC), revealing it met its primary endpoint.

In patients whose tumours expressed PD-L1 with a combined positive score (CPS) of at least 20, the findings demonstrated that, when used as a monotherapy, Keytruda improved overall survival (OS) rates by 39% compared to the EXTREME regimen of Merck KGaA’s Erbitux (cetuximab) plus cisplatin or carboplatin combined with 5-fluorouracil (5-FU). This equated to an extension of 14.9 months as a monotherapy compared to 10.7 months as part of the EXTREME regimen.

Additionally, the drug improved OS rates by 22% in patients PD-L1 tumours with a CPS score of at least 1 and when used in combination with chemotherapy, OS was improved by 23% regardless of PD-L1 status.

In the group with CPS of at least 20, objective response rate (ORR) stood at 23.3% for Keytruda as a monotherapy versus 36.1% for the EXTREME regimen. In the group with a CPS of at least 1, ORR was 19.1% for Keytruda compared to 34.9% for the regimen. There was no difference between the groups in regards to progression-free survival.

Lead investigator Barbara Burtness remarked: "Patients with PD-L1 expression live longer when they have initial treatment with Keytruda. It is thrilling to see these new data, which have the potential to alter the standard of care in the first-line treatment of head and neck cancer."

She continued: [Keytruda] appears to prolong life even when the cancer continues to grow, suggesting that it should be a first-line therapy in recurrent and metastatic head and neck cancer," adding: "whether [Keytruda] is given alone or with chemotherapy may depend on PD-L1 expression and we are conducting analyses to answer this question."