Vivacta Biotechnology (Shanghai) Co Ltd (Vivacta Bio), a China-based company spun out of the in vivo CAR-T platform of Beijing Grit Biotherapeutics Co Ltd (Grit Bio), announced on Saturday that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to GT801, Vivacta Bio's lead investigational product, for the treatment of autoimmune haemolytic anaemia (AIHA).

The designation is claimed to mark an important step in GT801's development for autoimmune diseases, and enables potential access to incentives supporting GT801's further development in AIHA in the United States.

According to Vivacta Bio, recent clinical investigations of CD19 CAR-T in refractory AIHA have opened a new treatment avenue through B-cell depletion.

The company says that GT801 is an investigational in vivo CAR-T therapy that combines mRNA with T-cell-targeted lipid nanoparticle (LNP) delivery technology. By delivering mRNA encoding an anti-CD19 chimeric antigen receptor (CAR) into patients' T cells, GT801 is designed to generate CAR-T cells directly in the body to recognise and eliminate CD19-positive B cells.

Preliminary clinical results for GT801 in patients with autoimmune diseases were presented in a poster at the 2026 American Society of Gene & Cell Therapy (ASGCT) Annual Meeting. According to the company, two patients with AIHA both achieved complete response (CR) following GT801 treatment. One patient achieved CR at Week 4 and remained in CR at the Week 8 and Month 3 assessments; the other achieved CR at Week 10. Sustained peripheral B-cell depletion was also observed, together with increased haemoglobin levels and reductions in lactate dehydrogenase, indirect bilirubin and reticulocyte counts. These preliminary findings indicated promising clinical prospect of GT801 in AIHA.