Currently, for diseases like FEVR, existing methods (laser, surgery) can only address complications (such as bleeding, detachment) but cannot fundamentally correct vascular developmental defects. Therapies targeting the underlying cause are completely lacking. However, in 2024, Boehringer Ingelheim licensed the FZD4 agonist SZN-413 for a potential total of $599 million. This is not just a single project deal but signifies strong recognition by a top pharmaceutical company of the entire target's biology and translational pathway. The development of SZN-413 indicates a new direction in the treatment of ophthalmic diseases.Next, let's get to know the FZD4 (Frizzled-4) target.

Yes-associated protein (YAP) is an oncoprotein that exists in an inactive form in the cytoplasm. As a key effector of the Hippo signaling pathway, it plays a central role in cell proliferation and differentiation regulation. Its abnormal activation drives tumorigenesis and is closely associated with tumor malignancy, recurrence, metastasis, and chemotherapy resistance.

CD19 is a type I transmembrane glycoprotein of the immunoglobulin superfamily, serving as a B cell-specific marker. It is continuously expressed throughout B cell development but disappears upon terminal differentiation into plasma cells. As it lacks intrinsic kinase activity, CD19 needs to form a B cell co-receptor complex with proteins such as CD21 and CD81 to function. Acting as a co-receptor for the B cell receptor (BCR), when the BCR recognizes an antigen, CD19 cooperates to bring the antigen protein closer and strengthens binding. It then rapidly activates kinases like Lyn, which are connected to its intracellular domain, while powerfully recruiting and activating key downstream signaling molecules such as PI3K, Vav, and PLC-γ. Through this mechanism, CD19 enhances BCR-mediated signal transduction, significantly lowers the activation threshold for B cells, and makes immune responses more sensitive and efficient.

c-MET is a receptor tyrosine kinase encoded by the MET proto-oncogene. It consists of an extracellular ligand-binding domain, a transmembrane region, and an intracellular tyrosine kinase domain, and is primarily located on the cell surface. Its sole ligand is Hepatocyte Growth Factor (HGF). Under normal physiological conditions, binding with its ligand HGF activates downstream signaling pathways, regulating cell proliferation, migration, differentiation, survival, and tissue repair. This is crucial for embryonic development and maintaining tissue homeostasis in adults. However, when the MET gene undergoes mutation, amplification, overexpression, or exon 14 skipping, the c-MET signaling pathway becomes abnormally and constitutively activated. This drives tumor growth, invasion, metastasis, and angiogenesis, and is also a key mechanism of resistance to EGFR-targeted therapies.