are there any new trials for progressive muscle atrophy?

My son age 41 was diagnosed with progressive muscle atrophy on 11-10-25. he has lost a lot of muscle mass and cant use his arms, shoulders much and has a hard time using his fingers on his left hand. his right hand still works a bit. Hoping to find out if there is anything out that can help bring back the use of all of his limbs. so far he can still eat and swallow and is walking good. he is taking a medication that is supposed to slow the progression but hoping there is something out there that can help him get back the use of his hands, fingers, arms & shoulders. thank you