Sarepta Therapeutics Inc. shares rose more than 60 percent to $26.24 on Wednesday after the company said it would start a rolling submission of its new drug application (NDA) for the Duchenne muscular dystrophy (DMD) drug eteplirsen. Nonclinical and chemistry, manufacturing and controls components of the NDA will be turned in by the end of this week, the company said, with the final clinical data component planned for submission by midyear.

The milestone follows an unexpected delay in Sarepta's progress last fall when U.S. regulators asked the company for additional data on the therapy, and the latest news could help the company catch up with competitor Biomarin Pharmaceutical Inc., which finished off a rolling NDA for its own exon 51-skipping DMD therapy, drisapersen, less than a month ago. (See BioWorld Today, Oct. 28, 2014, and April 29, 2015.)

"Should FDA accept the completed eteplirsen rolling NDA, we think there would be an absolutely crucial advisory committee meeting that may almost entirely determine the approvability of the application," Cowen and Co. analyst Ritu Baral wrote in a research note.

Sarepta's interim CEO and chief medical officer, Edward Kaye, was unavailable for comment. Former President and CEO Chris Garabedian stepped down earlier this year, also resigning his board seat.

Deutsche Bank research analyst Robyn Karnauskas characterized the NDA news as "incrementally positive," while noting that it's still "only the first step in many to successfully complete the NDA." Assuming a mid-2015 completion of the eteplirsen NDA, she suggested the therapy could be approved as soon as early 2016, after potential back-to-back FDA advisory committee panels for eteplirsen and drisapersen this fall.

Further uncertainty could lie in the resolution of ongoing intellectual property battles relating to eteplirsen. In 2014, the U.S. Patent and Trademark Office's Patent Trial and Appeal Board declared various patent interferences between certain patents held by Sarepta under a license from the University of Western Australia and patent applications held by Prosensa Holding NV, now part of Biomarin, under a license from Academisch Ziekenhuis Leiden related to exon 51- and exon 53-skipping therapies designed to treat DMD. (See BioWorld Today, Nov. 25, 2014.)

Prosensa also has rights to a European patent relating to the induction of exon skipping in eukaryotic cells. While Sarapta opposed the patent in the Opposition Division of the European Patent Office and succeeded in November 2011 in invalidating some of the patent's claims, the Opposition Division maintained in amended form certain claims of the patent relating to the treatment of DMD by skipping dystrophin exons 51 and 46.

Both Sarepta and Prosensa appealed the decision in June 2013, but with a final resolution still pending, the patent may provide the basis for Prosensa or other parties to assert that eteplirsen infringes on the patent, Sarepta said in a February regulatory filing.

As Sarepta eyes filing a marketing authorization application for eteplirsen in Europe, the company is working to both sort out the IP issues there and to secure a meeting with EMA authorities to present them with the additional data the company prepared for the FDA. That will likely happen within the next few months.

Among analysts covering Sarepta's shares, 10 (including Karnauskas) recommend holding on to them for now, while four analysts recommend buying and five others rate the shares a "strong buy," or equivalent. Among the 19 analysts tracked by Thomson Reuters, the median 12-month target price for Sarepta shares is $27.50, not far from its current value.

As the company continues to move toward completing the eteplirsen NDA, it is also starting enrollment for study 4658-203, testing the therapy in patients ages 4 to 6; working toward full enrollment of study 4658-301, a confirmatory phase III study of eteplirsen; and both parts of study 4053-101 in Europe, which is testing SRP-4053, a potential therapy to treat DMD in boys with genotypes amenable to exon 53 skipping.

Sarepta had more than $167 million in cash and investments at the end of the first quarter, a balance it expects will easily carry it into 2016. "In terms of an anticipated capital raise, we continue to be opportunistic with respect to our financing decisions, being mindful of our near- and midterm capital requirements, the broad capital market environment and the need to mitigate dilution where possible," Sarepta's chief financial officer, Sandy Mahatme, said on the company's most recent earnings call.