Sarepta's Duchenne gene therapy slows disease progression at three years

Adds CEO comments in paragraphs 4 and 5, background on disease in paragraph 6

By Mariam Sunny

Jan 26 (Reuters) - Sarepta Therapeutics' SRPT.O gene therapy for Duchenne muscular dystrophy slowed disease progression and showed sustained benefit in patients' ability to control and coordinate movement three years after treatment, sending its shares up more than 12%.

Elevidys helped patients, who were around nine years old on average and had not lost their ability to walk, perform tasks such as jumping and standing on one leg better than a pre-planned external control group of untreated patients.

The company said 52 patients who received Elevidys and remained in long-term follow‑up showed up to 73% reduction in the rate of decline on key functional measures such as time to rise from the floor and time to complete a 10-meter walk or run, compared with the external control group.

CEO Douglas Ingram said the long‑term data from the late-stage study not only confirm earlier signs of benefit but also test whether the therapy's advantages widen over time relative to how the disease naturally progresses.

He said the results highlight the importance of starting treatment early to alter the disease's course to avoid irreparable damage.

Duchenne is a hereditary neuromuscular disease that typically affects young boys and causes progressive muscle deterioration.

Sarepta has faced heightened scrutiny over the safety and effectiveness of Elevidys after two non-ambulatory teenage boys died due to acute liver failure linked to the therapy.

Oppenheimer analysts said while investors are generally skeptical of studies using external control groups, the data could improve physician and patient perceptions of Elevidys' benefit-risk profile and help accelerate commercial uptake.

Sarepta, which has been grappling with weakening sales, said no new safety issues were observed.

Elevidys is approved to treat ambulatory patients aged four and older, although it had failed to show a statistically significant improvement in motor function after 52 weeks in the late-stage study.

The therapy's label carries the U.S. health regulator's most serious safety warning for acute serious liver injury and acute failure of the organ, as well as stringent monitoring requirements after treatment.

(Reporting by Mariam Sunny in Bengaluru; Editing by Sriraj Kalluvila)

((Mariam.ESunny@thomsonreuters.com;))