12th Jun 2026 10:05
(Alliance News) - GSK PLC on Friday announced that momelotinib has received orphan drug designation from the US Food & Drug Administration, and the European Medicines Agency, to treat VEXAS syndrome.
VEXAS, or "Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic" syndrome, is a rare and life-threatening haemato-inflammatory condition which currently has no approved treatment options.
"It is a highly symptomatic progressive condition with poor prognosis and a 30-40% five-year mortality rate," GSK added.
The London-based pharmaceutical company said the orphan drug designations, which are granted for new medications with the potential to treat or prevent rare disorders, were supported by retrospective case studies. These showed that Janus kinase or JAK inhibitors, like momelotinib, "may be an effective therapeutic option for VEXAS".
It also cited "evidence from a case report that indicated potential clinical benefit from treatment with momelotinib, including improvements in symptoms and VEXAS-related inflammation and haematological manifestations."
At the 2026 European Hematology Association Congress, which started on Thursday and ends on Sunday, GSK will present its study design for the planned phase 2/3 ATLAS trial. ATLAS will evaluate momelotinib's efficacy and safety as a VEXAS treatment, supporting global regulatory submissions, and is part of an ongoing programme studying momelotinib's potential for multiple haematological conditions.
Momelotinib is currently available as Ojjaara in the US, for intermediate- or high-risk myelofibrosis in adults with anaemia, and as Omjjara in the UK and EU, for myelofibrosis with disease-related splenomegaly or symptoms in adults with moderate to severe anaemia. It is also approved as Omjjara for myelofibrosis in Japan.
Shares in GSK traded 1.9% higher at 2,000.66 pence on Friday morning in London.
By Emma Curzon, Alliance News reporter
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