Tolerance Bio licenses anti-IL-33 drug from Tanabe, with milestones of up to $560M

Tolerance Bio has expanded its thymus-targeted pipeline by licensing an anti-IL-33 antibody drug from Japan’s Tanabe Pharmaceutical.

According to Fierce Biotech on the 28th (local time), Tolerance Bio secured rights outside Japan to Tanabe Pharmaceutical’s investigational anti-IL-33 monoclonal antibody. The agreement includes milestone payments that could total up to $560 million (about 750.4 billion won). Specific financial terms were not disclosed.

The drug was previously known as MT-2990 and will be renamed TLB-33 under the agreement. Tanabe Pharmaceutical has evaluated the drug in five clinical trials involving more than 150 patients.

Tolerance Bio plans to advance TLB-33 into Phase 2 trials to assess its effects on preserving thymic function and enhancing immune resilience, while also exploring its potential in other immune disease indications.

Philadelphia-based Tolerance Bio launched in October 2024 with a $17.2 million seed investment. The company has focused on treating immune-mediated diseases by targeting the thymus.

Last month, the company signed an agreement with NeoImmuneTech worth up to $260 million to license efineptakin alfa, a long-acting IL-7 fusion protein. The decision was based on evidence that IL-7 promotes thymic function and T-cell differentiation, proliferation and survival.

In its announcement today, Tolerance Bio noted that IL-33 signaling contributes to thymic involution in inflammatory environments. The company believes that blocking IL-33 could preserve thymic function and enhance immune resilience.

Tolerance Bio CEO Francisco Leon said, “TLB-33 is an investigational antibody with substantial human safety and pharmacology data,” adding, “We will continue development by drawing on our team’s experience repositioning clinical-stage assets for high-value new indications.”

Leon added, “Together with our recently licensed long-acting IL-7 program, TLB-33 offers complementary approaches to preserving and restoring thymic function.”

The company plans to fund Phase 2 plans for TLB-33 and efineptakin alfa through a future financing round. Tolerance Bio said, “These programs are designed to preserve, regenerate and modulate thymic function,” adding, “We will build a leading therapeutic platform targeting thymic biology.”