Adagene and Third Arc Bio Select First Lead Candidate

San Diego, California, and Suzhou, China, September 10, 2026

Adagene and Third Arc Bio Advance First Lead

The selection of the first lead candidate represents an important milestone in the collaboration and moves the program from discovery toward clinical development. Under the expanded agreement, Third Arc Bio will sponsor and fund clinical development of the selected candidate, increasing its role in advancing the program toward potential human testing. The amended collaboration also increases the total potential payments to Adagene, including development and commercial-based milestone payments. Financial terms for the expanded agreement were not disclosed in the announcement, but the increased potential payments reflect the broader scope of the partnership and progression of the program. Adagene will retain a no-cost option to develop and commercialize the candidate molecules in Greater China, Singapore and South Korea. This regional option could provide Adagene with future opportunities to participate directly in development and commercialization activities if the program advances successfully. The collaboration builds on the companies’ original agreement, under which Third Arc Bio received rights to utilize Adagene’s technology for masked CD3 T cell engagers. The partnership is focused on applying precision antibody engineering to next-generation T cell-based cancer therapies.

SAFEbody Technology Targets Tumor Microenvironment

Adagene’s SAFEbody® technology is designed to address an important challenge associated with antibody therapeutics and T cell engagers: achieving effective tumor targeting while limiting on-target, off-tumor toxicity. The technology uses a precision masking approach to shield an antibody’s binding domain until the therapeutic reaches the appropriate tumor microenvironment. Once activated within the tumor microenvironment, the masked antibody is designed to engage its intended target. This approach is intended to potentially provide a wider therapeutic index, allowing therapeutic activity to be concentrated within tumors while reducing unwanted interactions with healthy tissues. For CD3 T cell engagers, the technology has particular relevance because these therapies are designed to bring T cells into contact with cancer cells to promote tumor-cell killing. The ability to control where and when T cell engagement occurs could potentially help address safety and tolerability challenges associated with systemic immune activation. Adagene’s proprietary Dynamic Precision Library (DPL) platform combines NEObody®, SAFEbody® and POWERbody™ technologies. The company uses computational biology and artificial intelligence alongside antibody engineering to discover and develop differentiated antibody-based cancer immunotherapies.

Third Arc Bio Expands T Cell Engager Pipeline

The expanded collaboration adds to Third Arc Bio’s growing portfolio of T cell engager programs and extends the company’s development strategy into masked CD3 therapeutics. Third Arc Bio has previously described its pipeline as including CD3- and CD28-targeting T cell engagers, while the partnership with Adagene provides access to SAFEbody precision masking technology for additional tumor-associated targets. For Adagene, the first lead selection provides further validation of the potential application of SAFEbody technology across multiple antibody therapeutic modalities. The company states that its platform can be applied to Fc-enhanced antibodies, antibody-drug conjugates (ADCs) and bi- or multispecific T cell engagers. Adagene’s own clinical pipeline includes muzastotug (ADG126), a masked anti-CTLA-4 SAFEbody currently being evaluated in Phase 1b/2 and Phase 2 studies, particularly in combination with anti-PD-1 therapy for microsatellite stable metastatic colorectal cancer. The selection of the first lead candidate by Third Arc Bio marks a significant development milestone for the partnership. The next stage will focus on clinical development, with Third Arc Bio assuming responsibility for funding and sponsoring the program. Future preclinical, clinical and regulatory data will determine whether the masked CD3 T cell engager can progress toward broader development and potential commercialization.

Source: Adagene, Third Arc Bio press release