Philadelphia-based Tolerance Bio, Inc. has licensed TLB-33 (MT-2990), a clinical-stage anti-IL-33 monoclonal antibody, from Japan-based Tanabe Pharma Corporation in a deal worth up to approximately USD 560 million in development and sales milestones, plus equity consideration and tiered royalties.
The deal gives Tolerance Bio a second clinical-stage thymus-focused program only weeks after licensing efineptakin alfa from NeoImmuneTech in a deal worth up to USD 260 million in milestones, as the firm rapidly builds a pipeline around preserving or restoring thymic function. TLB-33 is intended to block IL-33-associated thymic involution, while efineptakin alfa uses the IL-7 pathway to stimulate thymic and T-cell recovery.
Under the agreement, Tolerance Bio receives worldwide development and manufacturing rights to TLB-33 and exclusive commercialization rights outside Japan, while Tanabe retains Japanese commercialization rights. The antibody has already been evaluated in more than 150 subjects across five clinical studies, providing an existing human safety and pharmacology dataset. Tolerance Bio plans to begin Phase II development in 2027.
TLB-33 neutralizes IL-33, an inflammatory signaling protein released during tissue stress and injury. The company’s thymus-focused rationale is supported by preclinical research showing that IL-33 signaling can contribute to thymic involution during severe inflammation, while IL-33 blockade preserved thymic structure and T-cell immunity in animal models.