It is noted that this cooperation does not form a connected transaction, nor a material asset restructuring under the Administrative Measures on Material Asset Restructuring of Listed Companies. Therefore, there is no legal barriers to implement this cooperation.

Interleukin-2 (IL-2) was discovered in 1976 and was known as T-cell growth factor (TCGF). It is a globular glycoprotein vital in maintaining the function of T lymphocytes and natural killer (NK) cells. Produced mainly by activated T cells, IL-2 promotes T cell proliferation and differentiation, maintains T cell activity, stimulates the production, proliferation, and activation of NK cells, induces the production of cytotoxic T lymphocytes (CTL), as well as induces and activates lymphokine-activated killer cells (LAK) and tumor-infiltrating lymphocytes. Therefore, it has excellent antiviral and anticancer effects and potential for broad clinical applications.

However, the currently marketed wild-type IL-2 products, when at low doses, will preferentially bind to high-affinity receptors on the surface of Treg cells, producing immunosuppression and falling short of the expected therapeutic effect. Whereas high doses of IL-2 will neutralize the immunosuppression brought about by Treg activation by activating a large number of effector T cells, but resulting in higher toxicity and more side effects, as well as apoptosis.

Leto Laboratories innovated a unique approach to eliminate the binding to the IL2 Rα. It introduced additional disulfide bonds to IL-2 itself which not only enables IL-2 to be more structurally stable but also forms a barrier that allows it to disrupt the binding to IL-2Ra with minimal alteration.

Though the mutated molecules are unable to bind to endogenous α receptors in vivo, they can still bind to β and γ receptor subunits. Therefore, lowering or eliminating the interaction of IL-2 with α receptor subunits can be important in promoting therapeutic efficacy and reducing side effects of treatment in cancer patients. This project is currently under preclinical development.

This cooperation enriches TopAlliance’s R&D pipeline for cancer treatment, optimizes its arrangement in market strategy, and offers therapeutic options to the unmet clinical needs, bringing positive effects on its ongoing operations.