Aug 09, 2026 —
RiboX Therapeutics announced that the U.S. Food and Drug Administration has cleared its Investigational New Drug application for RXIM002, an investigational targeted LNP-delivered circular RNA-based in vivo CAR-T therapy for autoimmune cytopenias.
RiboX described RXIM002 as the world’s first circRNA-based in vivo CAR-T therapy to receive FDA IND clearance. The clearance supports initiation of the POPULUS-1 Phase 1 clinical trial, which will evaluate RXIM002 in patients with relapsed or refractory autoimmune cytopenias.
RXIM002 uses targeted lipid nanoparticles, or tLNPs, to deliver circular RNA encoding a CD19-targeting chimeric antigen receptor to T cells in vivo. The approach is designed to generate functional CAR-T cells directly inside the patient’s body, rather than requiring ex vivo T-cell collection, engineering, expansion, and reinfusion.
By enabling in situ generation of CAR-T cells, RXIM002 aims to bypass the complex and time-intensive manufacturing process used in conventional CAR-T therapies. In autoimmune disease, the therapy is designed to drive deep B-cell depletion, potentially supporting immune reset and durable drug-free remission.
The program was evaluated prior to IND submission in investigator-initiated trials in China involving autoimmune disease patients. RiboX submitted complete IIT data to the FDA as part of the IND package, including safety and early efficacy results from all treated patients. Follow-up remains ongoing, with some patients exceeding six months.
According to RiboX, the FDA permitted an accelerated dose-titration scheme and allowed a subcutaneous formulation as part of clinical development. The company said this could support a potentially outpatient treatment approach.
The POPULUS-1 trial will evaluate the safety, pharmacokinetics, pharmacodynamics, and early efficacy of RXIM002. The study will initially enroll patients with relapsed or refractory immune thrombocytopenia, or ITP, the most prevalent autoimmune cytopenia.
ITP is characterized by low platelet counts and increased risk of bruising and bleeding. The disease is driven by pathogenic autoantibodies associated with aberrant B-cell activation. RXIM002 is being developed to induce transient in vivo CAR-T-mediated depletion of pathogenic B cells while potentially preserving immune competence.
RiboX said the milestone supports its proprietary circular RNA and targeted LNP platforms, which are designed to enable durable expression, precision tissue targeting, and broad therapeutic applicability across multiple disease areas.
The IND clearance marks an important step for RNA-based in vivo cell therapy, combining circular RNA, targeted LNP delivery, and CAR-T biology in an off-the-shelf therapeutic format for autoimmune disease.
