On March 16, 2026, GC801 injection, an IgG (immunoglobulin G) degrading enzyme drug independently developed by Beijing Genecradle Therapeutics Co., Ltd. (hereinafter referred to as "Genecradle Therapeutics"), received the implied clinical trial approval from the National Medical Products Administration (NMPA) (Application No.: CXSL2501108). The indication applied for in this submission is: pre-treatment AAV antibody depletion for type 2 spinal muscular atrophy (SMA) gene therapy. This marks the fifth Class 1 new drug and the eighth registered clinical trial submitted by Genecradle Therapeutics.

▲ Image source: Screenshot from the CDE official website

As an engineered IgG antibody-degrading enzyme, the core advantage of GC801 injection lies in its highly efficient and specific IgG-cleaving activity. Based on the natural IdeS enzyme, the drug has been engineered and optimized through modifications to the IdeS polypeptide sequence, enhancing its cleavage activity against human IgG. Compared to wild-type IdeS, GC801 achieves stronger efficacy at lower doses. GC801 catalyzes cleavage at the lower hinge region of the heavy chain of all human IgG subclasses, rendering pre-existing antibodies functionally inactive and enabling their rapid metabolic degradation by the body, thereby attenuating or eliminating critical immunological barriers for various therapeutic scenarios dependent on IgG antibody modulation.

The indication applied for in this GC801 submission—pre-treatment AAV antibody depletion for type 2 SMA gene therapy—addresses a significant unmet clinical need. Spinal muscular atrophy (SMA) is a rare neuromuscular disorder in which patients typically face progressive muscle weakness and motor dysfunction. AAV-mediated gene therapy has emerged as one of the most promising therapeutic strategies. GC101 adeno-associated virus injection, an AAV gene therapy drug independently developed by Genecradle Therapeutics for spinal muscular atrophy, has demonstrated significant efficacy advantages in Phase I–III clinical studies, providing SMA patients with a more convenient and innovative treatment option offering long-term benefits. However, statistics indicate that approximately 30%–60% of the general population (including patients with type 2 SMA) harbor pre-existing neutralizing antibodies (IgG) against various AAV serotypes. These antibodies may impede viral vector entry into target cells, thereby affecting the accessibility and efficacy of gene therapy while increasing safety risks. Currently, there remains a lack of direct, effective, and safely controllable strategies for clearing pre-existing AAV antibodies in clinical practice. The IND approval of GC801 is expected to provide a novel intervention approach to address this critical limiting factor, opening a "green channel" for gene therapy in such patients.