(Reuters) -Shares of Sarepta sank 36% before the bell on Tuesday after a trial for two gene-targeted therapies for a muscle-wasting disease missed a key goal, deepening concerns about the company's treatment pipeline.

The latest setback comes after Sarepta's top-selling gene therapy, Elevidys, was briefly pulled from the market in July following the death of three patients from acute liver failure. The stock has lost about 80% of its value this year.

The latest trial enrolled 225 patients aged 6 to 13 with Duchenne muscular dystrophy (DMD) and tested casimersen and golodirsen, which belong to a class of drugs called phosphorodiamidate morpholino oligomers, or PMOs, designed to help produce functional dystrophin protein.

"The failure of the ... study exacerbates Sarepta's woes in the DMD space as both gene therapy and, now the PMO franchise, are likely to face increasing regulatory, payer, physician scrutiny," analysts at Baird said.

Duchenne muscular dystrophy is a rare genetic disorder that mostly affects boys, leading to progressive weakening of muscles over time.

"The miss is not entirely surprising, but adds some uncertainty around base business," said Brian Abrahams, head of global healthcare research at RBC Capital Markets.

"Pipeline may have potential, but remains early to meaningfully move the needle."

While patients showed numerical gains in climbing four steps after 96 weeks, the difference was not statistically significant.

Sarepta said the COVID-19 pandemic disrupted trial participation and data collection, potentially affecting the results and that it plans to meet with the U.S. Food and Drug Administration to discuss converting the drugs' current accelerated approvals into full approvals.

The company on Monday posted third-quarter revenue of $399.4 million, beating analysts' average expectation of $338.7 million.

(Reporting by Joel Jose in Bengaluru; Editing by Saumyadeb Chakrabarty)