Tempest Therapeutics, Inc. (Nasdaq: TPST) announced details of its in vivo CAR-T platform and plans to advance its lead candidate, TPST-4003, into an investigator-initiated clinical trial targeting nervous system autoimmune diseases, according to a press release dated July 15, 2026.

The trial will initially focus on patients with myasthenia gravis and multiple sclerosis, with enrollment expected to cover approximately 10 patients. First patient dosing is anticipated in the fourth quarter of 2026, with initial safety and pharmacodynamic data expected in the first half of 2027 and an interim clinical update, including preliminary efficacy data, in the second half of 2027.

TPST-4003 is a preclinical product candidate that combines the company's CD7-targeted mRNA lipid nanoparticle delivery platform with a dual-targeting CD19/BCMA CAR architecture. The same CAR construct is used in TPST-2003, the company's clinical-stage program, which the company said achieved a 100% complete response rate in interim Phase 1/2a data.

The planned study will assess safety, cellular kinetics, and pharmacodynamic activity. Key measures include treatment-emergent adverse events, generation of CAR-T and CAR-NK cells, CAR transgene copy number, and the depth of CD19+ B-cell depletion. Exploratory assessments may include detection of CAR-positive immune cells in cerebrospinal fluid.

Initial study planning has involved discussions with six prospective clinical centers with experience in neurological autoimmune diseases.

Tempest also disclosed two additional preclinical programs: TPST-001, targeting non-B-cell hematologic malignancies, and TPST-002, targeting solid tumors.

"We are excited to announce the strategic prioritization of our next-generation in vivo CAR-T pipeline and our plan to advance TPST-4003 toward an anticipated first patient dosing later this year," said Matt Angel, Ph.D., President and Chief Executive Officer of Tempest.