UPMC, Ziff Back ai3Bio's $48M Launch Round Against Autoimmune T Cells

ai3Bio launched with a $48M Series A to develop therapies that eliminate disease-causing Th17 cells rather than only interrupting the inflammatory signals they produce. Founding investors UPMC Enterprises and Ziff Capital Partners led the round, announced September 29, 2026, with Cockrell Interests and Tanis Ventures participating. The company did not disclose a valuation, individual check sizes, or a prior financing history under the ai3Bio name.

The Watertown, Massachusetts company is advancing two preclinical platforms around the same cellular thesis. STARx, which stands for Selective T cell Apoptosis Therapy, uses an antibody-guided lipid nanoparticle to deliver engineered mRNA into CD161-positive T cells. The payload is designed to activate the cGAS-STING pathway inside the targeted cell and trigger apoptosis, a programmed cell-death process intended to clear the cell without the inflammatory damage associated with other forms of cell death. T Deplete works differently: its antibody binds the targeted cells and recruits natural killer cells to eliminate them through antibody-dependent cellular cytotoxicity, a mechanism already used by multiple approved antibody medicines.

Both platforms aim at CD161, which ai3Bio says its computational work identified as a marker shared by malfunctioning Th17 and related inflammatory T-cell populations. That is where the artificial intelligence in the company's name fits: a discovery platform used to study diseased tissue and identify a cellular marker common across the T-cell populations it wants to target.

The capital is earmarked for IND-enabling work toward an initial patient trial targeted for 2027, a stage that typically includes manufacturing development, toxicology, dose selection, regulatory preparation, and the assays needed to show whether the intended immune cells were depleted without unacceptable effects elsewhere.

The company reports that its lipid-nanoparticle technology removed disease-causing Th17 cells in tests using blood samples from patients with autoimmune disease, and that T Deplete showed efficacy in a non-human-primate autoimmune model. Both claims are preclinical and company-reported; no human safety or efficacy data have been disclosed.

The competitive backdrop is crowded but differently aimed. Many established autoimmune therapies inhibit cytokines such as IL-17, IL-23, or TNF, while several newer approaches deplete B cells. ai3Bio is testing whether selected pathogenic T cells can be removed directly. Research has connected dysregulated Th17 biology with psoriasis, inflammatory bowel disease, rheumatoid arthritis, and multiple sclerosis, though the role of these cells varies by disease and patient, and a 2025 U.S. prevalence study estimated that about 15 million Americans had at least one of 105 autoimmune diseases between 2011 and 2022.