Mesoblast has placed its shares in a trading halt ahead of a crucial overnight meeting of the Oncologic Drugs Advisory Committee of the US healthcare regulator the Food and Drug Administration (FDA).

After an all day meeting Thursday, the FDA's Advisory Committee is scheduled to vote on whether the available clinical evidence is sufficient to approve Mesoblast's Ryoncil drug for the treatment of acute-Graft Versus Host Disease in children.

The company has suggested the vote is due around 7am AEST, with an analyst call to be potentially held around 10.30am Friday.

Mesoblast also has a secondary listing on the Nasdaq stock exchange.