Merck (MSD) is set to stop the Phase III KEYNOTE-598 trial of Keytruda in combination with ipilimumab (Yervoy) for treating patients with metastatic non-small cell lung cancer (NSCLC) whose tumours express PD-L1.

The latest decision follows an independent Data Monitoring Committee (DMC) recommendation, which determined that the benefit/risk profile of the combination did not support continuity of the trial.

Keytruda is an anti-PD-1 therapy that works by increasing the ability of the body’s immune system to help detect and fight tumour cells.

The randomised, double-blind trial evaluated Keytruda in combination with ipilimumab compared to Keytruda monotherapy for the first-line treatment of patients with metastatic NSCLC whose tumours express PD‑L1 with no EGFR or ALK genomic tumour aberrations.

An interim analysis data showed that Keytruda plus ipilimumab demonstrated no incremental benefit in overall survival (OS) or progression-free survival (PFS), the study’s dual primary endpoints as compared to Keytruda alone and crossed futility boundaries.

The combination was also linked to a higher incidence of adverse events (AEs) as compared to Keytruda monotherapy.

Merck will notify the study investigators of the DMC recommendation.

The DMC also recommended the patients of the study to discontinue treatment with ipilimumab/placebo.

Merck Research Laboratories senior vice-president and global clinical development head Dr Roy Baynes said: “It is very clear that in this study, the addition of ipilimumab did not add clinical benefit but did add toxicity.

“Keytruda monotherapy remains a standard of care for the treatment of certain patients with metastatic non-small cell lung cancer whose tumours express PD-L1.”

At present, over 1,200 trials are evaluating Keytruda across a wide variety of cancers and treatment settings.

In June, Merck reported that the Phase III KEYNOTE-361 trial analysing Keytruda plus chemotherapy failed to meet its pre-specified co-primary endpoints of OS and PFS for advanced or metastatic urothelial carcinoma.