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) -- A handful of pre-teen boys suffering with Duchenne muscular dystrophy have now been treated with

Sarepta Therapeutics'

(SRPT) - Get Sarepta Therapeutics, Inc. Report

eteplirsen for 84 weeks. The boys are still walking, defying the debilitating and progressive nature of a disease that would be forcing them into wheelchairs without treatment.

As with previous updates from Sarepta's eteplirsen study, no significant safety problems were reported. No serious adverse events, no hospitalizations or treatment discontinuations.

Well, there was one disruption in the study but it was actually more evidence of eteplirsen's profound benefit for DMD patients. Here's how Sarepta describes it:

One boy in the placebo/delayed-treatment cohort was not able to perform the 6MWT at the Week 84 clinic visit due to a physical injury unrelated to treatment, and therefore had no 6MWT data captured at the Week 84 time point. The boy has recovered from the injury, continues to be ambulatory and is expected to be evaluated on the 6MWT at future clinic visits.

Sarepta doesn't say, but the injured boy suffered a broken leg, according to people familiar with his case. The leg healed and the boy is walking again normally. Boys with DMD who break a leg aren't supposed to recover and walk again normally, but in this case, he is.

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After 84 weeks, DMD patients treated with eteplirsen are walking, on average, 9.2 meters less over six minutes than they were at the start of the study. When the same walk test was performed at 74 weeks, the decrease in walking distance was 2.2 meters, on average.

Another small group of DMD patients started the study on placebo and switched over to eteplirsen after 24 weeks. Initially, the walking ability of these boys declined while on placebo, but it's since stabilized following treatment with eteplirsen.

"We now have demonstrated stability of walking for over a year and a half in the original eteplirsen treatment cohort in boys who are now 11 years old on average, an age when many DMD boys have lost the ability to walk," said Sarepta CEO Chris Garabedian, in a statement. "In addition, the placebo/delayed-treatment cohort, which has now received eteplirsen for over a year, has demonstrated a stabilization in walking ability for 48 weeks compared with the precipitous decline observed earlier in the study before dystrophin was confirmed in these patients. Overall, we believe the data across all treatment cohorts are remarkably consistent and continue to support eteplirsen as a potential treatment option in DMD."

Sarepta continues to work work with the FDA to reach agreement on an accelerated approval filing strategy for eteplirsen.

Today's positive update from the eteplirsen study makes Sarepta's case even stronger.

Sarepta shares are up 5 percent to $40.10 in early Wednesday trading.

-- Reported by Adam Feuerstein in Boston.

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Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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