Vivacta Bio, a spin-off company of Grit Biotherapeutics advancing in vivo CAR-T therapies for oncology and autoimmune diseases, has announced encouraging initial data from an investigator-initiated, first-in-human study of GT801, a T-LNP/mRNA–based in vivo CAR-T candidate targeting CD19.
The results were presented at the 2025 American Society of Hematology (ASH) annual meeting in Orlando, Florida, in an oral session by Pin Wang, chief scientific officer of Grit Biotherapeutics.
The presentation, “Precision In Vivo CAR-T Generation via CLAMP-Enabled mRNA Delivery: Toward Scalable and Translatable Cell Therapy,” highlighted early clinical activity of GT801 and its potential to reshape CAR-T treatment delivery.
The phase 1 investigator-initiated study is evaluating the safety, tolerability, and preliminary efficacy of repeat GT801 dosing in patients with relapsed or refractory CD19-positive B-cell malignancies. As of the November 30, 2025 data cutoff, two patients with non-Hodgkin’s lymphoma had completed multiple GT801 administrations without lymphodepleting chemotherapy, demonstrating the feasibility of generating functional CAR-T cells in vivo in the absence of cytotoxic conditioning.
Patient 1 received three doses of 0.5 mg, and Patient 2 received four doses of 1.5 mg. GT801 was generally well tolerated. Both patients showed high CAR expression within circulating T cells. Durable and repeatable CAR-T expansion was observed following each GT801 administration. No CAR expression was detected in peripheral blood monocytes, suggesting negligible off‑target delivery of GT801 and supporting high selectivity of the T‑LNP platform.
GT801 induced rapid and profound pharmacodynamic activity, resulting in deep B-cell depletion in peripheral blood and across multiple tissues, with B cells effectively cleared in bone marrow and lymph node biopsies. By Week 4 following the final GT801 infusion, both patients achieved a partial response based on investigator assessment.
“We are encouraged by the promising safety profile and compelling efficacy signals observed with GT801 in heavily pretreated NHL patients,” said Yarong Liu, founder and CEO of Vivacta Bio.
“These initial findings demonstrate GT801’s ability to generate potent, repeatable CAR-T responses without lymphodepleting chemotherapy – a major step forward for scalability, patient accessibility, and commercial viability.”
Jim Cornall is editor of Deeptech Digest and publisher at Ayr Coastal Media. He is an award-winning writer, editor, photographer, broadcaster, designer and author. Contact Jim here.