The Well-Worn Path of ERTs

Last July, Ultragenyx Pharmaceutical (RARE) released positive results from a phase 3 study of its enzyme replacement therapy rhGUS (recombinant human beta-glucuronidase) in the lysosomal storage disorder, mucopolysaccharidosis 7 (MPS 7).

The phase 3 program doesn’t look anything like most other registration-grade programs you’re used to seeing. It included just 12 patients and had no defined primary endpoint, nor a defined control arm. In fact, the U.S. FDA advised Ultragenyx NOT to declare a primary endpoint, agreeing instead to evaluate the “totality of the data.” Ultragenyx will file for approval in the first half of this year, and the drug should receive an FDA decision within six months.