Merck KGaA's cancer vaccine L-BLP25 (formerly known as Stimuvax) has missed its primary endpoint in a late-stage non-small cell lung cancer trial, but helped certain subsets of patients.

The German group said the START trial involving more than 1,500 patients with unresectable, locally-advanced stage IIIa or IIIb NSCLC did not meet its aim to demonstrate a statistically significant improvement in overall survival. Further analyses are planned in the coming weeks to explore the potential benefit-risk profile of the vaccine in certain populations, Merck added.

The ongoing clinical programme of L-BLP25 which includes studies in the Asia Pacific region will continue, pending discussion with relevant regulatory agencies. The Darmstadt-based company quoted Frances Shepherd of the University of Toronto and coordinating investigator of the study, as saying that "it is disappointing that the START trial did not meet its primary endpoint, in particular for patients suffering from NSCLC".

However, she noted that "notable treatment effects were observed in certain subgroups of patients and warrant further investigation of L-BLP25". Nevertheless, investors are disappointed and Merck shares at 10.55 this morning (UK time) were down 3.4% to 98.12 euros.