Shares of biotech Sarepta Therapeutics shot off to the moon Tuesday after the company announced early data on its experimental gene therapy to treat Duchenne muscular dystrophy. Sarepta stock was up as much as 67% during trading, settling closer to a 35% bump later in the afternoon, or just under $140 per share.

The investor frenzy was galvanized by some promising, though very preliminary, data presented at the firm’s first-ever R&D day. Sarepta’s treatment, for now dubbed AAVrh74.MHCK7.micro-Dystrophin--yes, you read that right--was reportedly able to dramatically cut the levels of an enzyme called creatine kinase (CK) associated with muscle damage while also significantly boosting the production of micro-dystrophin, which assists basic movement functions, in the patients who took it. Duchenne muscular dystrophy is a nasty, muscle-wasting disease that usually claims its victim’s lives by their mid-20s, eating away at their muscles by barring the production of dystrophin.

“I have been waiting my entire 49-year career to find a therapy that dramatically reduces CK levels and creates significant levels of dystrophin,” said Dr. Jerry Mendell of Nationwide Children’s Hospital said in a statement announcing the early stage gene therapy clinical trial results. “Although the data are early and preliminary, these results, if they persist and are confirmed in additional patients, will represent an unprecedented advancement in the treatment of DMD.”

A number of biopharma analysts and medical experts were stunned by Sarepta’s preliminary results themselves. “In biotech sometimes we get to witness history unfolding. Man, how technologies are improving so quickly,” tweeted Brad Loncar, CEO of Loncar Investments and an avid biotech industry watcher. JPMorgan analyst Anupam Rama said the results “meaningfully beat even the highest of expectations.”

Mendell’s point about the results’ preliminary nature is also worth keeping in mind. This early gene therapy study involved just three patients--although, granted, trials for rare disorders like Duchenne muscular dystrophy have very limited patient pools. But Sarepta also has a bit of a controversial history at the Food and Drug Administration (FDA). Its pioneering approval for a different muscular dystrophy treatment called Exondys 51 drew plenty of blowback from critics (and was cleared by a razor thin margin despite the initial objections of the FDA’s own advisers) who argued it didn’t show significant benefit.

An initial reading of the tea leaves suggests some more optimism about Sarepta’s new Duchenne gene therapy. The question is whether or not the early results will persist.

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