Mesoblast chief executive and founder Silviu Itescu says the US Food and Drug Administration has not put a “hold” on the clinical development program of its key remestemcel-L drug.

The biotech’s shares fell another 5.7 per cent on Wednesday morning to $1.57 after losing nearly 16 per cent on Tuesday. The slide began after the powerful US regulator raised more questions about its flagship experimental drug for treating acute graft versus host disease (SR-aGVHD) in children and acute respiratory distress syndrome (ARDS) in adults with COVID-19.