In short
BMN 333 is an investigational medicine being studied for achondroplasia, a genetic condition that causes short stature. It is a long-acting C-type natriuretic peptide (CNP) given by subcutaneous injection, developed by BioMarin Pharmaceutical. One authorised Phase 4 trial is comparing BMN 333 against vosoritide in 185 children with achondroplasia.
BMN 333 is an investigational medicine being developed for achondroplasia, a rare genetic condition that affects bone growth and causes short stature. It is a long-acting C-type natriuretic peptide (CNP), a protein-based substance given by subcutaneous injection. BMN 333 has no marketing authorisation and is still being studied in clinical trials.
Key points
- BMN 333 is an investigational long-acting C-type natriuretic peptide (CNP) for achondroplasia.
- The registered trial is Phase 4 and compares BMN 333 with vosoritide.
- 185 children with achondroplasia are planned to take part.
- The main measure is annualised growth velocity (AGV) at Week 52.
- The trial is currently authorised but not yet recruiting.
- BMN 333 is given by subcutaneous injection.
What is BMN 333?
BMN 333 is a long-acting C-type natriuretic peptide (CNP), a protein-based substance developed by BioMarin Pharmaceutical. It is also known as BMN-333 and is classified as a natriuretic peptide replacement. In the EU Clinical Trials Information System, BMN 333 is recorded as an investigational substance with no marketing authorisation. A paediatric formulation of BMN 333 exists, reflecting that the condition it targets affects children.
How does BMN 333 work?
BMN 333 acts as a natriuretic peptide replacement. C-type natriuretic peptide is a natural protein that plays a role in regulating bone growth. In achondroplasia, a genetic change leads to overactivity of the fibroblast growth factor receptor 3 (FGFR3), which slows bone growth. By providing a long-acting form of CNP, BMN 333 is designed to counteract this effect and support normal bone growth.
Which conditions is BMN 333 studied for?
- Achondroplasia — the most common form of short-limbed dwarfism, caused by a genetic change affecting bone growth. BMN 333 is being studied in children with this condition.
- Hypochondroplasia — a related but milder form of short stature, where BMN 333 has reached Phase 1 studies.
How is BMN 333 given?
BMN 333 is given as a subcutaneous injection, meaning it is injected under the skin. The product used in the trial is a powder for solution for injection. The registered trial does not report the exact dose of BMN 333, as the dose is listed as 0.00 micrograms in the registry record, which indicates the dose was not reported.
What do the clinical trials show?
One clinical trial of BMN 333 is registered in the EU Clinical Trials Information System. It is a Phase 4 study that compares BMN 333 with vosoritide, an already authorised medicine for achondroplasia sold under the name Voxzogo. The trial plans to enrol 185 children with achondroplasia.
The trial has two parts. Phase 2 of the study evaluates the effect of three different doses of BMN 333 compared with vosoritide on annualised growth velocity (AGV), which measures how fast a child grows over a year. Phase 3 evaluates the effect of a selected dose of BMN 333 compared with vosoritide on AGV after 52 weeks of treatment.
The main outcome measure is annualised growth velocity at Week 52. The trial status is authorised, meaning it has received regulatory approval to proceed but is not yet recruiting participants.
What side effects are known?
The supplementary source does not provide a detailed list of side effects for BMN 333. Adverse events data have been reported in the development programme, but the available source does not specify which side effects have been observed. As an investigational medicine, the full safety profile of BMN 333 is still being established through clinical trials.