Mesoblast’s Dream sours

Having continued to develop Revascor after its phase II failure, Mesoblast has smashed head first into the likeliest phase III outcome: also failure. In the 537-patient Dream-HF trial, the allogeneic cell therapy did not reduce recurrent non-fatal decompensated heart failure events, the trial’s primary endpoint, and Mesoblast’s shares closed down 15% on the Australian exchange today. Remarkably, the company still believes it has a path to approval, based on a 60% reduction in cardiac death, the eighth of 30 secondary endpoints listed on the study’s clinicaltrials.gov record. However, this reduction in mortality was seen only in a subgroup of 206 patients with class II heart failure, the milder group in the trial. Mesoblast has concluded that Revascor must reduce mortality by mechanisms distinct from those of existing drugs, which it says reduce hospitalisation rates but do not significantly impact cardiac mortality. Mesoblast says it will meet with the FDA to discuss Revascor’s registration, and while there is certainly great need for effective heart failure medicines, it seems unlikely that the FDA will be convinced by what can only be classed as an exploratory finding on a secondary endpoint in a minority of patients.