The MPS Society is deeply disappointed to learn of the FDA’s Complete Response Letter to Ultragenyx, which will significantly delay the progression of the UXIII clinical trial. While this setback is frustrating, we want to make one thing clear to our community across the UK and around the world: this delay is due to technical and manufacturing issues, not due to the science, data, or the promise of this treatment.
Ultragenyx has already committed to addressing the concerns raised, and we have full confidence in their team to address any issues as swiftly and safely as possible.
But this moment is bigger than a single trial. It is a stark reminder that rare diseases are a global challenge, not confined by borders. The barriers we face regulatory, logistical, scientific are shared across nations, and so must be our response.
We urge our global rare disease community to stand with us - families, clinicians, researchers, regulators, industry leaders - because we can no longer afford to work in silos. We must demand smarter, faster and more ethical clinical trial pathways that serve the people at the heart of this: our children, our families, our future.
In several MPS diseases, we already have powerful tools like the heparan sulfate biomarker that can detect treatment effects early. These biomarkers not only help demonstrate efficacy but can also signal when a treatment is not working, avoiding unnecessary delays, costs, and unethical trial designs that are ill-suited to small, vulnerable patient populations.
We call for the urgent integration of biomarker-based trial models, which offer more rapid, cost-effective and patient-centred approaches. Let us be clear: we are not asking for shortcuts. We are asking for innovation, urgency and accountability.
In light of recent World Health Organization (WHO) recognition of the unique challenges rare disease communities face, we call on global regulators, scientific leaders, and healthcare systems to work with us, not against the clock, but against the loss of time these children cannot afford.
The MPS Society is committed to fostering cross-border collaboration, and we reaffirm our pledge:
To amplify the voices of our community
To demand ethical, efficient clinical trials
And to work with all partners who share our mission to help people “Live a Rare Life Better”
Now is the time. Let’s move forward together.
