How the U.S. FDA might view the latest Duchenne muscular dystrophy (DMD) phase III data with gene therapy RGX-202 became the question for Regenxbio Inc., shares of which  (NASDAQ:RGNX) closed May 14 at $6.25, down 38%, or $3.80, after the results were made public.

With top-line pivotal data with gene therapy RGX-202 for Duchenne muscular dystrophy (DMD) due in the next quarter, Regenxbio Inc. rolled out positive interim data from the phase I/II Affinity trial at the Muscular Dystrophy Association Clinical and Scientific Conference (MDA) in Orlando, Fla., where Bridgebio Pharma Inc., Capricor Therapeutics Inc., and Solid Biosciences Inc. also had clinical findings to talk about.

The regulatory clouds that have been darkening the U.S. FDA landscape of late for Uniqure NV’s gene therapy AMT-130 in Huntington’s disease may be parting a bit with the announced departure of Vinay Prasad as director of the agency’s CBER at the end of April.

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.

In handing a win to Regenxbio Inc., the U.S. Court of Appeals for the Federal Circuit also cleared some leaves from the 101 patent eligibility threshold after years of Supreme Court decisions cluttering the passageway.

With the PDUFA date fast approaching for Regenxbio Inc.’s gene therapy RGX-121, the U.S. FDA placed the drug on clinical hold along with another, RGX-111, after preliminary analysis of a single case of neoplasm (specifically, an intraventricular central nervous system tumor) in a participant treated in the phase I/II study with the latter treatment.

How the U.S. FDA might respond became a serious question for Wall Street as Sarepta Therapeutics Inc. made known a second death due to acute liver failure with gene therapy Elevidys (delandistrogene moxeparvovec), cleared for Duchenne muscular dystrophy (DMD). Shares of Cambridge, Mass.-based Sarepta (NASDAQ:SRPT) closed June 16 at $20.94, down $15.24, or 42%, as Wall Street digested the news.

Regenxbio Inc.’s gene therapy in treating Duchenne muscular dystrophy (DMD) produced positive initial phase I/II results from its first five patients. However, the company’s stock (NASDAQ:RGNX) shuddered on June 5 as shares closed at $8.36 each, a drop of 17% on the day.