On November 4, 2025 Radiant Biotherapeutics, a biotechnology company committed to advancing a breakthrough antibody approach, the Multabody, for a broad range of therapeutic areas, including cancer and infectious diseases, reported new data at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) 40th Annual Meeting demonstrating its lead oncology candidate, RBT-101, exhibited robust, durable and complete tumor regression while avoiding liver toxicity, in a MC38 colorectal mouse tumor model.
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Radiant’s proprietary Multabody technology uniquely harnesses natural mechanisms to effectively engage multiple disease targets with unmatched strength, precise tunability, and exceptional breadth. 4-1BB is a clinically validated immune checkpoint target that elicits potent anti-tumor immunity and enhanced T cell responses but has eluded safe and effective therapeutic targeting by traditional 4-1BB agonists due to systemic and Fc-mediated liver toxicity. Radiant has leveraged its Multabody platform to develop RBT-101, a multivalent 4-1BB agonist that does not rely on traditional antibody methods to enhance potency, binding strength or durability.
Key Highlights from SITC (Free SITC Whitepaper) 2025 Poster Presentation:
RBT-101 achieved sustained complete tumor regression in MC38 colorectal mouse tumor model
RBT-101 demonstrated long-lived anti-tumor immunological memory; no detectable tumor growth was observed in mice that were re-challenged with MC38 tumor cells after previous successful treatment
RBT-101 demonstrated no signs of liver toxicity, in contrast to benchmark 4-1BB agonist urelumab
"Our data to be presented at SITC (Free SITC Whitepaper) demonstrates that RBT-101 achieves what first-generation 4-1BB agonists could not – delivering robust anti-tumor activity without liver toxicity," said Jo Hulme, Ph.D., CSO of Radiant. "This validates our Multabody platform’s potential to address a broad range of therapeutic targets while avoiding the inherent limitations of conventional antibody-based approaches, as RBT-101 drove potent, tunable and safe agonism of 4-1BB that more closely mimicked natural ligand biology. We look forward to the continued development of Multabodies as promising therapeutics in oncology and other disease areas."
The poster, titled "Multabodies: A next-generation approach for cancer immunotherapy and 4-1BB agonist therapy," will be presented onsite on Friday, November 7, 2025, and will also be available on the SITC (Free SITC Whitepaper) virtual meeting platform beginning November 7 at 9 a.m. ET.
(Press release, Radiant Biotherapeutics, NOV 4, 2025, View Source [SID1234659398])