Sarepta Therapeutics has just announced having obtained conditional marketing authorization (MA) in the United States for its antisense oligonucleotide SRP-4045 (casimersen – AMONDYS 45) in Duchenne muscular dystrophy (DMD). SRP-4045 targets skipping exon 45 of the DMD gene, an abnormality that affects 8% of boys with DMD.
A production of dystrophin but a clinical benefit to be demonstrated
In its press release dated February 25, 2021, the laboratory specifies that this conditional MA granted to SRP-4045 is based on the first results of the ESSENCE trial, still underway in several countries including France. This trial, which evaluates both SRP-4045 and SRP-5053, includes 222 boys with DMD aged 7 to 13 worldwide, half of them being affected by exon 45 skipping.
The results presented in March 2019 to the FDA in the MA application showed that the level of dystrophin in the muscles of boys after 48 weeks of treatment with SRP-4045 was increased by almost 1.8%. The demonstration of a clinical benefit in this population of boys is requested by the FDA for the MA to be final. In addition, SRP-4045 is well tolerated, without effects on renal function, and with some side effects such as respiratory infections, cough, fever, headache, joint pain in particular.