Otsuka Pharmaceutical Co. Ltd. reaped positive results from an open-label phase II study of repinatrabit (JNT-517) in adolescents with phenylketonuria (PKU), a rare disease marked by the inability to break down the amino acid phenylalanine.

At the current pace of innovation in the U.S. rare disease space, developing and approving therapies for just half of the 10,000-plus known rare diseases would take more than 160 years, Bradley Campbell, president and CEO of Amicus Therapeutics Inc., recently told the Senate Committee on Aging.

A lot of distance lies between talking regulatory flexibility and actually being flexible. That message was driven home again after Uniqure NV disclosed in its latest earnings report March 2 that the U.S. FDA wants a sham-controlled study before it will consider approval of the company’s gene therapy AMT-130 in Huntington’s, a rare disease currently affecting about 41,000 people in the U.S.