On April 20, 2026 Calidi Biotherapeutics, Inc. (NYSE American: CLDI) ("Calidi" or the "Company"), a biotechnology company pioneering the development of targeted genetic medicines, reported new data at the American Association of Cancer Research (AACR) (Free AACR Whitepaper) annual meeting in San Diego, California on April 19, 2026. The Company demonstrated new data on its approach of simultaneously activating T-cells while inducing the expression of T-cell engagers specifically in situ in the tumor microenvironment ("TME"). The poster is available here.
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RedTail is Calidi’s systemically delivered virotherapy platform designed to selectively target tumors, remodel the TME, and enable high-level expression of therapeutic genetic payloads directly at the tumor site while limiting peripheral exposure. CLD-401, the lead candidate derived from the RedTail platform, is engineered to express high levels of IL-15 superagonist ("IL-15 SA"), a known CD8⁺ T-cell, NK cell, and gamma delta (γδ) T-cell activator, in the TME. The Company expects to file an IND for CLD-401 by the end of 2026.
Data presented at the AACR (Free AACR Whitepaper) meeting showcased RedTail viruses that can express both a functional T-cell engager, capable of binding targeted solid tumor cells, and IL-15 SA at high concentrations, allowing for simultaneous T-cell activation and high expression in situ of a T-cell engager. T-cell engagers have shown exceptional efficacy in hematological malignancies but have failed to show clinical benefit in solid tumors where the TME inhibits immune cell infiltration and T-cell activity. By remodeling the TME and driving T-cell activation in concert with expression of a T-cell engager, RedTail is designed to overcome these historical limitations.
The Company is developing CLD-501, a lead candidate targeting TROP2, a cell-surface glycoprotein. TROP2 expression in normal tissue and the high potential for off-tumor / on-target toxicity has made it a difficult target for T-cell engagers. The RedTail approach confines expression of the T-cell engager to the TME, limiting off-tumor interactions. The Company is pursuing additional T-cell engager targets like EGFR, EpCAM, and Nectin-4.
"Data presented at AACR (Free AACR Whitepaper) show the advances we have made with the RedTail platform, our first lead, CLD-401, and our progress in addressing a central challenge in immuno-oncology: how to deliver tumor-specific T-cell engagers effectively in solid tumors" said Eric Poma, PhD, Chief Executive Officer of Calidi. "We believe RedTail represents a major breakthrough in the ability to deliver genetic payloads, including in situ T-cell engagers in a targeted fashion to distal sites of disease through systemic administration."
"The data we presented at AACR (Free AACR Whitepaper) highlight the ability of the RedTail platform to functionally overexpress complex biologics including cytokines and T-cell engagers, and profoundly alter the tumor microenvironment" said Antonio F. Santidrian, PhD, Chief Scientific Officer and Head of Technical Operations at Calidi. "This tumor-restricted approach enables targeting of antigens such as TROP2, something that has not been effectively accomplished with existing T-cell engager therapies.
The Company continues to expand the functionality of the RedTail platform and is also actively pursuing strategic partnerships to accelerate clinical development and broaden the impact of its RedTail platform.
(Press release, Calidi Biotherapeutics, APR 20, 2026, View Source [SID1234664584])