Mirum

May 2026: Introducing Mirum Pharmaceuticals

Mirum Pharmaceuticals is a small, California-based biotechnology company focused on developing treatments for rare diseases. In May 2026, it acquired the global rights to zilurgisertib from Incyte.

Zilurgisertib is an investigational, oral, small molecule, activin receptor-like kinase 2 (ALK2) inhibitor for the treatment of FOP by targeting the ACVR1/ALK2 signalling pathway involved in abnormal bone formation.

This move has drawn significant attention within the FOP community, as Mirum’s experience in rare disease development positions it as a key player in the potential future of this programme, including its progression through regulatory review and possible access pathways for patients.

Visit their website: Mirum Pharmaceuticals: Relentlessly Rare

Read a letter from their CEO: Letter to the FOP Community

Mirum’s Pipeline: Pipeline

Announcement: Regulatory Progress for Zilurgisertib in FOP

US pharmaceutical company Incyte has, for some years, been developing zilurgisertib.

Results from their current PROGRESS Phase 2 trial in adults and young people with FOP appear to have been positive. Consequently, data from Part 1 of the PROGRESS trial (involving patients aged 12 and up) has been filed with the US Food and Drug Administration (FDA) for marketing approval in the USA with a decision date expected in September 2026.

Incyte are scheduled to present the data at a medical conference in Chicago June 2026 where we will learn more. While, there is no news yet about filing the data to UK regulatory agency (MHRA) or potential timelines for access in the UK, this remains a normal and exciting first step.

Acquisition by Mirum Pharmaceuticals

Furthermore, it was announced yesterday, 6^th May 2026, that Mirum Pharmaceuticals has entered into an exclusive licence of worldwide rights to zilurgisertib from Incyte. This is not unusual for Biotechs and small pharma companies. In this case, zilurgisertib will likely be a better fit in the portfolio of Mirum – which already markets rare disease medicines across a spectrum of conditions – whereas Incyte tends to specialise in blood diseases and cancer.

Essentially, Mirum has acquired zilurgisertib and there is every indication that they will aggressively continue the global development of this exciting potential therapy for people living with FOP.

FOP Friends look forward to working with Mirum in facilitating access to the UK FOP community.

Key milestones to anticipate

* August 2026: Anticipated presentation of trial results at the IFOPA’s FOP Drug Development Forum in Canada.

* September 26, 2026: The FDA’s target decision date (PDUFA) for the application.

While we currently await the formal publication of the trial results to better understand the treatment’s safety and effectiveness, there is a strong sense of hope that these details will be shared this summer. We look forward to the insights that will be provided during the upcoming forum in August.

If you have any questions, contact Andrew: Dr Andrew Rankin

More information visit: IFOPA

Note: PDUFA stands for the Prescription Drug User Fee Act

When a company, e.g Mirum or Incyte, files a New Drug Application (NDA), the FDA doesn’t just review it indefinitely. Under this Act, the FDA agrees to a specific deadline to finish its review and give an answer. This deadline is called the PDUFA date.

Because this drug was granted Priority Review, the FDA is legally committed to a faster 6-month timeline rather than the standard 10-month review.