Dr. Fumihiko Urano discusses why Wolfram syndrome can be difficult to study and how rare disease trials can better connect objective measures with patient experience.
Wolfram syndrome is a rare genetic disease that often starts in childhood. It typically begins with diabetes and vision loss caused by optic nerve damage. As the condition progresses, people may also develop hearing loss, bladder dysfunction, hormone imbalances and serious brain and nerve complications.
Currently, there are no approved treatments to slow or stop the disease. This makes early diagnosis, specialized care and clinical research vital. Because Wolfram syndrome affects many organ systems and varies between patients, it remains a major challenge for researchers.
Dr. Fumihiko Urano, MD, PhD, has studied Wolfram syndrome for more than two decades, including the cellular stress pathways that help explain why insulin-producing beta cells and certain nerve cells are especially vulnerable in the disease. He also led the HELIOS Phase II trial, which evaluated an investigational treatment candidate for its potential use to address cellular stress pathways involved in Wolfram syndrome.
Samuel E. Schechter Professor of Medicine
Division of Endocrinology, Metabolism & Lipid Research
WashU Medicine
In an exclusive Xtalks Clinical Edge interview, Dr. Urano, Principal Investigator of the HELIOS trial and Samuel E. Schechter Professor of Medicine in the Division of Endocrinology, Metabolism & Lipid Research at WashU Medicine, discussed what clinical researchers should understand about Wolfram syndrome, small open-label studies and the design considerations facing rare disease trials.
Why Wolfram Syndrome Remains a High-Unmet-Need Rare Disease
“Wolfram syndrome is a rare, progressive, monogenic neurodegenerative disease,” said Dr. Urano. “Monogenic means that a mutation in a single gene is sufficient to cause the disease.”
Dr. Urano explained that Wolfram syndrome usually stems from changes in the WFS1 gene. Wolframin, the protein encoded with the WFS1 gene, is associated with endoplasmic reticulum, the cellular compartment involved in protein folding and calcium handling. It is also linked to mitochondria, which help cells produce energy.
When WFS1 function is disrupted, cells with the heaviest workloads are hit first. This includes insulin-producing beta cells in the pancreas and nerve cells in the optic nerve and brain, helping explain why many patients develop diabetes and vision loss early in life.
These complications often accumulate over time. Patients may experience hearing loss, bladder dysfunction and hormone-related problems affecting the body’s ability to regulate water. Later in the disease course, progressive changes affecting the brainstem and cerebellum can lead to serious challenges with balance, breathing and swallowing.
“A family may see a child diagnosed with diabetes around age six, vision loss in the teens and steady accumulation of disability after that,” said Dr. Urano.
Current care focuses on managing diabetes and treating complications as they arise.
“We manage the diabetes with insulin and we treat complications as they arise, and we have nothing that slows down the underlying neurodegeneration,” said Dr. Urano.
“Because the disease affects multiple organ systems, including the pancreas, brain, eyes and bladder, there is no single clean readout that captures whether a patient is doing better.”
— Dr. Fumihiko Urano
He noted that the same cellular stress biology involved in Wolfram syndrome is also seen in more common conditions, including type 1 diabetes, type 2 diabetes and several neurodegenerative diseases.
Designing Trials Around a Multisystem, Slowly Progressive Disease
Recruitment is a major hurdle in Wolfram syndrome research. Patients are few and geographically dispersed, making enrollment and retention difficult.
Wolfram syndrome is unpredictable. Even among patients with the same genetic diagnosis, progression can vary substantially. This creates challenges for researchers trying to determine whether a participant is improving, stabilizing or declining.
“Because the disease affects multiple organ systems, pancreas, brain, eyes, bladder, there is no single clean readout that captures whether a patient is doing better,” said Dr. Urano.
Another issue is time. “From the patient’s perspective, they may not think it is slow. But from the FDA’s perspective, it is slowly progressive,” said Dr. Urano.
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Slowly progressive means a study may need to run long enough to detect change or use sensitive biomarkers to identify earlier signals.
Natural history data help researchers understand how the disease progresses without treatment.
“For many rare genetic diseases, we simply lack good quantitative data on how fast each feature declines,” said Dr. Urano. “That is why building a registry and longitudinal natural history dataset has been our priority.”
In addition, many people with Wolfram syndrome are children, which raises practical and ethical questions around consent, testing burden and which outcomes matter most to a growing child and their family.
Reading Signals in Small, Open-Label Rare Disease Studies
Rare disease trials often work with small data sets. HELIOS was a Phase II study sponsored by Amylyx Pharmaceuticals and conducted in collaboration with researchers at WashU Medicine with Dr. Urano serving as principal investigator, enrolling 12 adults with Wolfram syndrome in a single-site, single-arm, open-label design.
Dr. Urano emphasized that this type of study should be interpreted carefully. Without a placebo group, it can be difficult to know how much of a change is due to the investigational treatment, natural disease variability or the additional clinical attention participants receive during a study.
“We have to be honest about what the design can and cannot tell us,” said Dr. Urano. “A study like that is hypothesis-generating.”
Dr. Urano said small studies can be useful when results are consistent across multiple measures. In HELIOS, several independent measures moved in the same direction, including C-peptide, HbA1c, continuous glucose monitoring data and visual acuity.
“When multiple distinct readouts move the same way and they line up with known biology of the drug, that is more convincing than any single endpoint,” said Dr. Urano.
Natural history data can also help researchers see whether “staying the same” may be meaningful when decline is expected.
“Listening systematically to patients and clinicians is not soft at all. It is part of how you decide which outcomes are worth measuring in the first place and how you interpret them once you have them.”
— Dr. Fumihiko Urano
Making Clinical Outcomes Meaningful to Patients
Clinical tests can show biological changes, but they do not always show what those changes mean in daily life. Dr. Urano said this is especially important in a multisystem disease like Wolfram syndrome, where a measurable change may affect how a patient sees, manages blood sugar or functions day-to-day.
“A change that looks modest on the chart can be the difference between a teenager being able to read a screen or not, or between needing less insulin and having fewer dangerous hypoglycemia events,” said Dr. Urano.
HELIOS included qualitative interviews alongside objective endpoints, as well as global impression of change measures from both patients and clinicians. These interviews helped researchers understand whether objective changes were reflected in patients’ day-to-day experiences.
Patient perspective may help surface symptoms that standardized instruments may miss.
“Listening systematically to patients and clinicians is not soft at all,” said Dr. Urano. “It is part of how you decide which outcomes are worth measuring in the first place and how you interpret them once you have them.”
Building Strong Trials for Small Rare Disease Populations
When asked about future Phase III trial design, more generally, he said late-stage rare disease development must balance the need for strong evidence with the realities of enrolling and retaining a small, dispersed patient population.
“The central tension in late-stage rare disease development is rigor versus feasibility,” said Dr. Urano. “You want the cleanest possible evidence, which usually means randomization and a control, and you also have to actually enroll and retain a small, dispersed population without overburdening them.”
That means endpoint selection is critical. Endpoints should be objective, meaningful to patients and, where possible, validated. Trial assumptions should also be grounded in the expected effect size and natural history of the disease.
A concurrent placebo or comparator may be preferred when ethical and feasible. When a placebo arm is difficult, researchers may need to consider natural history data or external controls, with regulator alignment in advance.
In a multisystem disease, participants may require multiple tests. Consolidating visits, using remote or home-based assessments where appropriate and partnering with patient organizations early can help make a study more feasible.
“Feasible and rigorous are not opposites if you design for both from the beginning,” said Dr. Urano.
Wolfram syndrome offers a useful case study in the challenges of rare disease research.
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