Pfizer has officially entered the race to cure Duchenne muscular dystrophy with gene therapy, joining Cambridge-based Sarepta Therapeutics and Solid Biosciences as the only companies to use the experimental technology on a boy with the muscle-wasting disease.

Pfizer (NYSE: PFE) announced on Thursday that the first patient in a small, early-stage trial of its gene therapy drug had been dosed on March 22. Earlier this year, both Sarepta (Nasdaq: SRPT) and Solid Biosciences (Nasdaq: SLDB) began their own clinical studies of similar drugs, which are designed to insert healthy genes into a person’s cells to replace missing or faulty ones.

Solid, though, appears to have fallen behind. The company disclosed in March that the FDA had halted its trial due to safety concerns. Sarepta, which already has an approved drug for Duchenne that can help about 13 percent of patients, has not reported any safety issues in its gene therapy study.

Duchenne, which affects around 15,000 people in the U.S., is marked by the absence of dystrophin, a protein that protects muscle cells. Boys with Duchenne are slowly robbed of their movement. They typically die by their late teens or early 20s.

Pfizer, Sarepta and Solid Biosciences are each developing drugs made up of a shortened version of the dystrophin gene. This “microdystrophin” is designed to be delivered into a patient’s cells using a type of virus.

Pfizer got its Duchenne drug through its 2016 acquisition of North Carolina-based Bamboo Therapeutics. While Pfizer is headquartered in New York, and the trial is taking place at Duke University Medical Center, some of the research and development work took place at its office in Kendall Square.