Amryt Pharma shares surged in London and New York after the firm reported positive clinical results for its key pipeline product.
The Irish-led firm said Filsuvez, its prospective treatment for a currently incurable skin-blistering disorder, had performed strongly in a phase three trial. It involved 223 patients, including 156 children, in 28 countries over a 27-month span.
The disease, epidermolysis bullosa (EB), afflicts an estimated 30,000 people in the US - the most likely initial market - and 500,000 worldwide.
Chief executive Joe Wiley said Filsuvez, if approved by US and EU authorities, would become the first drug for a global market worth more than $1bn (€850m).
Filsuvez would be protected from competition for seven years in the US market and 10 years in the EU.
Mr Wiley said the trial outcome represents "a significant milestone for Amryt".
The announcement coincided with Amryt's official exit yesterday from the Euronext Dublin stock exchange. Amryt made the move following its July listing on the Nasdaq Global Select Market. It also trades on London's AIM market.
Amryt's shares surged more than 30pc overnight on the Nasdaq and settled yesterday below $14 a share, still up 24pc. Its London-listed shares rose 50pc in early trade and closed at 218 pence, up 36pc.
Most of Amryt's investors today are based in the US, where the firm also has most of its operations following its September 2019 takeover of the bankrupt Aegerion Pharmaceuticals in Boston.
The doctor who led the Filsuvez trial, Prof Johannes Kern of the Royal Melbourne Hospital in Australia, said EB is "an incredibly distressing condition" involving chronic wounds that do not heal.
It is a genetic skin disorder that causes the skin layers and internal body linings to separate. No drug currently treats the condition effectively.
"I am very excited by the possibility that a treatment such as Filsuvez could potentially accelerate wound healing and alleviate the symptoms for those affected," Prof Kern said.