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Capstan Therapeutics Announces Initiation of Phase 1 Trial of Lead In Vivo CAR-T Therapy, CPTX2309, for Treating Autoimmune Disease

juni 11, 2025

Human Health

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  • CPTX2309 is a targeted lipid nanoparticle that delivers an anti-CD19 CAR mRNA preferentially to CD8-expressing cytotoxic T cells
  • mRNA-based approach is designed to achieve rapid, deep, and transient B cell depletion without the need for chemotherapy, cell manipulation, viral vectors, and DNA integration
  •  First-in-human clinical trial underway to evaluate safety, tolerability, and pharmacodynamic activity of CPTX2309 in healthy volunteers

SAN DIEGO--(BUSINESS WIRE)--Capstan Therapeutics, Inc. (“Capstan”), a clinical-stage biotechnology company dedicated to advancing in vivo reprogramming of cells through RNA delivery using targeted lipid nanoparticles (tLNP), today announced successful dosing of the first participants in its Phase 1 trial of CPTX2309, Capstan’s lead anti-CD19 in vivo CAR-T candidate, for the treatment of B cell-mediated autoimmune disorders.

The Phase 1 trial will assess the safety, tolerability, pharmacokinetics, and pharmacodynamic activity (i.e., peripheral B cell depletion and recovery) of CPTX2309 treatment in healthy volunteers at various dose levels. Preclinical studies demonstrated rapid, deep, and transient B cell depletion in blood and tissues, which supported the clinical evaluation of CPTX2309 at the planned dose levels and regimens.

With CPTX2309, our therapeutic goal is to achieve immune reset through rapid and profound B cell depletion using a transient, tunable, and fully off-the-shelf in vivo CAR-T technology. The focus on a Phase 1 healthy volunteer population allows us to dose escalate efficiently, and importantly, underscores the potential safety advantages of an approach that does not involve lymphodepletion or permanent CAR integration into the genome. The objective of this trial is to determine a pharmacologically active dose (or doses) that can be advanced into Phase 2 studies to treat patients with autoimmune disease.

Ramin Farzaneh-Far

M.D., Chief Medical Officer at Capstan

Contacts

Investors:
Miguel Arcinas
Senior Vice President of Corporate Development
Capstan Therapeutics, Inc.
ir@capstantx.com

Media:
Rhiannon Jeselonis
Ten Bridge Communications
capstan@tenbridgecommunications.com