Systemic delivery of adeno-associated viral (AAV) vectors has traditionally been used in the clinic for liver-directed programs such as hemophilia A and hemophilia B. With the approval of Zolgensma® for the treatment of spinal muscular atrophy type I (SMA1), high dose systemic gene therapy has become a promising approach for systemic and neuromuscular transduction for various indications. Here, we discuss emerging findings on safety and efficacy from recent clinical trials utilizing high dose systemic gene therapy. In particular, we highlight previously unappreciated observations related to safety, and discuss possible causes and future directions.
