US-based pharmaceutical company MSD has reported outcomes from a Phase III trial of Keytruda (pembrolizumab) for treating resected, locally advanced head and neck squamous cell carcinoma (LA-HNSCC).

The KEYNOTE-689 trial demonstrated that Keytruda enhanced event-free survival (EFS) in individuals with LA-HNSCC when given as a perioperative treatment regimen.

The randomised, active-controlled trial enrolled 714 individuals with stage III or IVA, resected LA-HNSCC.

Its primary endpoint was EFS, while its secondary endpoints included overall survival (OS), major pathological response (mPR), safety, and pathological complete response.

Subjects in the open-label trial were randomised to receive either a combination therapy featuring Keytruda or standard of care (SOC) radiotherapy alone.

Findings from the initial interim analysis showed that when given as a perioperative treatment combined with SOC radiotherapy, Keytruda improved EFS against SOC radiotherapy alone.

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After a median follow-up at 38.3 months, the therapy had decreased the EFS event risk by 34% in subjects whose combined positive score (CPS) was ten or higher.

Keytruda’s safety profile was consistent with that found in prior studies, with no new safety signals identified.

MSD Research Laboratories senior vice-president and head of oncology, global clinical development Dr Marjorie Green said: “As the 12th positive pivotal trial for a Keytruda-based regimen in earlier-stage cancers, the results from KEYNOTE-689 are a testament to our commitment to address an unmet need in this important area of research.

“These compelling results illustrate the potential of this regimen to change the landscape of care for certain patients facing this challenging disease.”

Based on these results, a supplemental biologics licence application (sBLA) for Keytruda is currently under priority review by the US Food and Drug Administration (FDA), with a decision expected by 23 June 2025.

Last month, MSD and BioCity Biopharmaceuticals partnered to assess Keytruda in combination with BC3195 in a global Phase I/II study for advanced or metastatic solid tumours.