US pharmaceutical company Merck & Co Inc (NYSE:MRK), known as MSD outside the US and Canada, on Monday announced new long-term data demonstrating sustained survival benefits of Keytruda (pembrolizumab) in patients with non-small cell lung cancer (NSCLC).

The findings, presented at the European Society for Medical Oncology (ESMO) Congress 2025, include results from several KEYNOTE clinical trials evaluating both perioperative and monotherapy treatment regimens.

Five-year exploratory data from the Phase 3 KEYNOTE-671 trial showed clinically meaningful improvements in overall survival and event-free survival when Keytruda was used with chemotherapy before surgery and continued as monotherapy afterward. The treatment achieved a hazard ratio of 0.74 for overall survival and 0.58 for event-free survival versus chemotherapy alone in patients with resectable stage II-IIIB NSCLC.

Eight- and ten-year follow-up analyses from KEYNOTE-024, -042, -001, and -010 confirmed that Keytruda monotherapy continued to improve survival outcomes in certain patients with locally advanced or metastatic NSCLC. Across these studies, Keytruda consistently outperformed chemotherapy in median overall survival, particularly among patients with higher tumour proportion scores.

According to Dr Heather Wakelee of Stanford Medicine, the durability of benefit supports pembrolizumab-based perioperative regimens as a standard of care for earlier-stage disease. Merck noted that these results reinforce Keytruda's established role across multiple tumour types, including melanoma, head and neck, bladder, and endometrial cancers.