But last September, Sarepta Therapeutics (NASDAQ: SRPT) became the first to win FDA approval of a Duchenne drug, eteplirsen (Exondys 51), and Marathon Pharmaceuticals followed with the second FDA-approved Duchenne-treating drug, deflazacort (Emflaza), earlier this month.
Sarepta’s drug is approved for a subset of Duchenne patients, roughly 13 percent with a specific genetic malfunction, for which it is supposed to slow the progression of the disease.
Gene therapy and gene editing offer a potentially much longer lasting solution by supplying genetic instructions for a patient’s body to produce a muscle-protecting protein, dystrophin, that people with Duchenne lack.
CRISPR-Cas9 is essentially a pair of molecular scissors guided to a cell’s nucleus by a strand of RNA, where it snips out a defective gene—in Exonics’s case, a mutation that prevents the production of dystrophin—and replaces it with a functioning one.
Olsen is the company’s chief science adviser.