Shares of Mesoblast (ASX:MSB) tanked as much as 58.3% down to A$0.455, preparing for the worst trading session ever observed in the company, if the current trends persist.

The plummet came after the U.S.

FDA declined the company’s developed cell therapy intended for children under 12 years.

The therapy focused on treating a type of complication that often arises in the aftermath of stem cell or bone marrow transplant.

Mesoblast mentioned that the health regulator requested additional data to justify the marketing approval of the lead product remestemcel-L.

The company had appealed to the FDA for an approval of a cell therapy purposed to treat children disparaged by a type of graft versus host disease (GvHD), whose symptoms either did not respond to standard steroid therapy or recurred while continuing treatment.

With this news, the value of Mesoblast’s shares fell to their lowest since August 10, 2005.

Despite this setback, Mesoblast previously topped the losses on the ASX All Ordinaries index and saw over 52.5 million shares change hands compared to the usual 30-day average volume of approximately 2.7 million shares.

Up until the latest closing, the shares of Mesoblast were up by 25.3% Year-To-Date.

Mesoblast is a biopharma company that specializes in developing innovative cellular medicines to treat serious and life-threatening inflammatory ailments.