FDA Grants Orphan Drug Designation to Vivacta Bio's In Vivo CAR-T Therapy GT801
The U.S. Food and Drug Administration has granted Orphan Drug Designation to GT801, an investigational in vivo CAR-T therapy from Vivacta Bio, for autoimmune hemolytic anemia (AIHA), the company announced. Vivacta Bio is a spin-out of Beijing Grit Biotherapeutics' in vivo CAR-T platform.
- The FDA granted Orphan Drug Designation to GT801 for autoimmune hemolytic anemia, according to Vivacta Bio.
- GT801 is an investigational anti-CD19 in vivo CAR-T therapy using mRNA and T-cell-targeted lipid nanoparticles.
- Two AIHA patients both achieved complete response in preliminary data presented at the 2026 ASGCT Annual Meeting.
- Possible incentives include tax credits for qualified trial expenses, user fee exemption and seven years of market exclusivity after approval.
- Vivacta Bio was established on June 25, 2025, as a spin-out of Grit Bio's in vivo CAR-T platform.
What the designation covers
Vivacta Biotechnology (Shanghai) Co., Ltd., known as Vivacta Bio, said the FDA has granted Orphan Drug Designation (ODD) to GT801, its lead investigational product, for the treatment of AIHA. According to the company, the designation is an important step in GT801's development for autoimmune diseases and enables potential access to incentives that support further development in AIHA in the United States.
The FDA program is intended to encourage the development of treatments for rare diseases. Subject to applicable requirements, sponsors of designated products may be eligible for tax credits for qualified clinical trial expenses, an exemption from marketing application user fees, and the potential for seven years of orphan drug market exclusivity following marketing approval, according to the release.
The disease and the treatment approach
AIHA is an autoimmune disorder in which autoantibodies drive excessive destruction of red blood cells. Symptoms may include anemia, fatigue and shortness of breath, and severe cases can be life-threatening. The company says some patients continue to have inadequate disease control despite multiple lines of therapy.
The release points to recent clinical investigations of CD19 CAR-T in refractory AIHA, which it says have opened a new treatment avenue through B-cell depletion. Simplifying treatment and improving access, while continuing to evaluate safety and efficacy, remain key areas for further development, according to the company.
GT801 is designed to work differently from conventional cell therapies. It combines mRNA with T-cell-targeted lipid nanoparticle (LNP) delivery technology. The mRNA encodes an anti-CD19 chimeric antigen receptor (CAR) and is delivered into patients' T cells, so that CAR-T cells are generated directly in the body to recognize and eliminate CD19-positive B cells.
Early clinical data
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. Two patients with AIHA both achieved complete response (CR) after GT801 treatment. One reached CR at Week 4 and remained in CR at the Week 8 and Month 3 assessments. The other reached CR at Week 10.
The company also reported sustained peripheral B-cell depletion, together with increased hemoglobin levels and reductions in lactate dehydrogenase, indirect bilirubin and reticulocyte counts. It describes these preliminary findings as indicating a promising clinical prospect for GT801 in AIHA. The data come from two patients, so they remain early.
Platform and company background
Vivacta Bio was established on June 25, 2025, and was spun out of Grit Bio's in vivo CAR-T platform. It focuses on in vivo CAR-T for oncology and autoimmune diseases. According to the company, expressing CAR directly in patients' T cells removes the need for cell isolation, ex vivo expansion and lymphodepletion, and could address the high costs, lengthy treatment timelines and toxicity associated with those steps.
The company describes GT801 as combining ionizable cationic lipids with its CLAMP technology platform, which features a T-cell-targeting VHH antibody, site-specific conjugation and precisely controlled ligand density. It says this design improves T cell targeting while limiting nonspecific uptake. GT801 is engineered to generate durable CAR-T cells in the patient and to support repeat dosing.
What it means
The designation does not signal approval, and GT801 remains investigational. It does give the program access to the FDA incentives described above if it proceeds in AIHA in the United States. Yarong Liu, Ph.D., Founder, Chairperson and Chief Executive Officer of Grit Bio, called it "an important milestone in the project's global development in autoimmune diseases." She said Grit Bio and Vivacta Bio will continue to "build a stronger body of clinical evidence" and make treatment options more accessible to patients.
