On Jun. 30, 2025, AbbVie and Capstan Therapeutics announced a definitive agreement under which AbbVie will acquire Capstan, including CPTX2309, a potential first-in-class in vivo tLNP anti-CD19 CAR-T therapy candidate, currently in Phase 1, in development for the treatment of B cell-mediated autoimmune diseases. Additionally, AbbVie will acquire Capstan’s proprietary tLNP platform technology designed to deliver RNA payloads, such as mRNA, capable of engineering specific cell types in vivo.

B cells contribute to the pathogenesis of autoimmune diseases. CD19 is a cell surface receptor expressed on B cells and is a clinically validated target for B cell depletion using ex vivo CAR-T cell therapy in autoimmune diseases. CPTX2309, a product of Capstan’s proprietary technology platform that includes hepatic de-targeting, delivers an mRNA payload encoding an anti-CD19 CAR preferentially to reprogram CD8-expressing cytotoxic T cells.

This process is achieved in vivo, without the need for lymphodepletion preconditioning and complex ex vivo manufacturing. The in vivo-modified CD8-expressing T cells will transiently express the CD19 CAR and deplete B cells in the periphery and tissues.

Depletion of autoreactive antibody-producing pathogenic memory B cells and repopulation with naïve B cells, resulting in immune reset, has the potential to prevent disease progression and induce clinical remission.

Under the terms of the agreement, AbbVie will pay up to $2.1 billion in cash at closing to acquire Capstan, subject to certain customary adjustments. The transaction is subject to the satisfaction of customary closing conditions, including expiration of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act.