PHILADELPHIA, PA — Tolerance Bio Inc. has secured global development rights to an experimental immune therapy from Japan’s Tanabe Pharma Corporation in a licensing agreement carrying potential milestone payments of approximately $560 million, expanding the Philadelphia biotechnology company’s clinical pipeline ahead of planned Phase 2 trials in 2027.
The agreement gives Tolerance Bio exclusive worldwide rights to develop and manufacture MT-2990, renamed TLB-33, and exclusive commercialization rights outside Japan. Tanabe Pharma will retain commercialization rights in its home market.
The transaction includes potential development and sales milestone payments totaling approximately $560 million, along with equity consideration and tiered royalties on net sales.
The milestone figure represents contingent payments tied to future development and commercial outcomes rather than an immediate transaction value.
TLB-33 is a monoclonal antibody designed to block interleukin-33, or IL-33, an immune signaling protein associated with inflammatory responses and tissue injury.
Tolerance Bio plans to evaluate whether inhibiting IL-33 can preserve thymic function and support immune resilience, extending the drug’s development into therapeutic applications involving the body’s immune system.
The thymus plays a central role in the maturation of T cells, which are essential to immune defense. Its function declines with age and can deteriorate during periods of inflammation, potentially affecting the body’s ability to respond to infections and other immune challenges.
TLB-33 has previously been evaluated in more than 150 participants across five clinical studies, generating safety, tolerability and pharmacologic data that Tolerance Bio intends to use in advancing the antibody into additional indications.
The company expects to begin Phase 2 clinical development in 2027, initially examining the drug’s potential to preserve thymic function. Other immune-related indications are also under consideration.
The acquisition of development rights follows Tolerance Bio’s recent licensing of efineptakin alfa, a long-acting interleukin-7 therapy developed by NeoImmuneTech.
The two programs target different immune pathways. TLB-33 is intended to inhibit inflammatory signaling associated with thymic deterioration, while the IL-7 program represents a separate approach to supporting immune function.
Together, the assets broaden Tolerance Bio’s clinical-stage development portfolio, which also encompasses research involving messenger RNA and cell-based therapies.
Francisco Leon, chief executive officer of Tolerance Bio, said the company sees a potential connection between IL-33 activity and the deterioration of thymic tissue during inflammatory conditions.
“IL-33 signaling has been implicated in thymic involution in inflammatory settings, and we believe that blocking IL-33 offers an opportunity to preserve thymic function and improve immune resilience,” Leon said.
The therapeutic approach remains under clinical investigation, with the planned Phase 2 program intended to evaluate whether the biological rationale translates into benefits for patients.
Tolerance Bio is also preparing to complete a financing round to support the clinical development of TLB-33 and efineptakin alfa.
The company has experience within its management team advancing existing clinical-stage compounds into new therapeutic indications, including work associated with Celimmune and Provention Bio.
TLB-33 is a human immunoglobulin G1 monoclonal antibody that binds to and neutralizes IL-33, a protein released in response to cellular stress or tissue damage.
The signaling pathway has been implicated in inflammatory processes associated with thymic dysfunction, including age-related decline and acute deterioration linked to certain immune conditions.
By licensing an antibody with existing human clinical data, Tolerance Bio is pursuing a development strategy built around repositioning previously studied compounds for potential new uses involving thymic preservation and immune health.
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