Sarepta Therapeutics (SRPT -1.52%) could have a serious new competitor on the horizon. According to some fresh clinical data from Regenxbio (RGNX -5.84%), another biotech, the company is making headway with a gene therapy for Duchenne muscular dystrophy (DMD), the condition that's Sarepta's focus.
Does an upcoming new player on the scene pose a big-enough threat to Sarepta to justify selling the stock today? The answer is a bit more complicated than merely "no," so let's dive in and clarify the issue.
A new competitor looks to find a niche
Regenxbio's gene therapy program is called RGX-202, and it could provide a measure of long-lasting relief to patients with DMD. The concept of RGX-202, as well as Sarepta's Elevidys therapy, is to replace the dysfunctional copies of a patient's disease-related genes with synthetically designed functional versions, such that when those genes are expressed by cells, the correct protein is produced rather than a dysfunctional version. Then the patient's symptoms, like muscle weakness and mobility issues, hopefully start to abate.
While such an approach is unlikely to affect 100% of a patient's muscle cells, meaning that it probably won't be completely curative, fixing even a portion of the problem could be enough for patients to experience improvements to their functional mobility and their ability to take care of themselves. And if the genetic fixes the therapy does manage to make end up being durable, it has a real shot at slowing the pace of the disease's progression, which would be a major win even if other potential benefits didn't pan out.
Per some preliminary data it released March 5 from RGX-202's phase 1/2 clinical trial, of the four patients presently enrolled in the trial, two of them exhibited gene expression patterns at upwards of 75% of what would be expected in a healthy person. The gene-editing therapy accomplished the changes it set out to do, and no serious adverse events were reported.
Now, the company is gathering data about how effective the therapy is at actually restoring patients' muscle strength and functionality, with the phase 2 portion of the trial wrapping up mid-year and the phase 3 trial starting shortly thereafter, pending regulatory permission.
It is between very unlikely and impossible that the one-dose format advanced by Regenxbio is in any way compatible with co-administration with Sarepta's one-dose therapy Elevidys. People who receive one therapy will not be eligible to get the other. In other words, if Regenxbio can get its candidate commercialized sometime next year, and given that it has a fast-track regulatory designation as well as a pair of other designations, it could indeed conceivably eat into Sarepta's market share.
Don't jump the gun here, but be vigilant
Despite the favorable data shared by Regenxbio, it would be unwise to ditch your shares of Sarepta today. It has four medicines for DMD already on the market, more in its research and development (R&D) pipeline, and it brought in more than $1.2 billion in revenue in 2023.
This August, it could get regulators to agree with its petition to expand the eligible patient population for Elevidys to include people with DMD of all ages, rather than only treating toddlers. Sarepta is also seeking to convert its expedited approval for the drug into a full approval, and that would be a key catalyst for the stock if regulators are on board.
Furthermore, DMD is a difficult illness to treat. There is no guarantee that Regenxbio will be able to advance its candidate through late-stage clinical trials. And while the company was willing to share some of the early data that look favorable, that data did not actually indicate that patients were experiencing fewer symptoms, only that their candidate was effective at editing the targeted genes in some of the patients treated with it.
So it may not end up actually taking a bite out of Sarepta's business in the way that investors are fearing, though it's still very possible down the line.
