On June 2, 2025 Calidi Biotherapeutics Inc. (NYSE American: CLDI) ("Calidi"), a clinical-stage biotechnology company pioneering the development of systemic oncolytic targeted immunotherapies with the ability to deliver genetic payloads, reported the presentation of its lead RedTail platform candidate, CLD-401, at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting (Press release, Calidi Biotherapeutics, JUN 2, 2025, View Source [SID1234653601]).
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Calidi has previously demonstrated its pioneering efforts in developing an enveloped form of its proprietary oncolytic virus that is significantly more resistant to immune clearance than non-enveloped forms, allowing for systemic delivery and efficacy in syngeneic tumor-bearing pre-clinical models. Calidi has further advanced this technology with CLD-401, its first therapeutic candidate from the RedTail platform. New data presented at the meeting demonstrate a novel genetic modification in which a chimeric CD55 receptor is incorporated into the envelope shielding the virus. Because CD55 receptor expression acts as a robust inhibitor of complement, this modification further enhances the virus’s resistance to rapid clearance by the humoral immune system following intravenous administration.
In addition, the RedTail viral platform also allows for the delivery of potent genetic payloads directly into the tumor microenvironment. CLD-401 expresses an IL-15 superagonist, a next-generation cytokine known to activate and expand natural killer (NK) cells and CD8+ T cells—key components of the immune system with demonstrated clinical efficacy.
"The integration of CD55 into our RedTail platform marks a major advancement in systemic virotherapy," said Antonio F. Santidrian, PhD, Chief Scientific Officer and Head of Technical Operations at Calidi. "By improving the shielding of the virus from complement-mediated destruction, we enhance its stability in circulation and enable the in situ expression of immune-activating payloads—such as the IL-15 superagonist—directly within the tumor microenvironment, where they can stimulate a robust antitumor immune response."
"RedTail is the result of over a decade of focused innovation at Calidi," added Eric Poma, PhD, Chief Executive Officer. "Our systemic approach overcomes the limitations of traditional intratumoral oncolytic viruses and enables the treatment of metastatic cancers through intravenous administration. The use of a chimeric CD55 enhancement is a critical enabler of this vision."
Calidi is currently conducting IND-enabling studies for CLD-401 and anticipates submitting an Investigational New Drug (IND) application in the second half of 2026. The company is also actively pursuing strategic partnerships to accelerate clinical development and broaden the impact of its RedTail platform
A copy of the ASCO (Free ASCO Whitepaper) poster featuring the CD55 data is available.