Full Analysis of the Mechanisms of VEGF-Targeted Drugs: How Anti-Angiogenic Therapy Is Changing Cancer Treatment

I. What is VEGF and Why Is It an Important Target?

VEGF is a key pro-angiogenic signaling molecule. By binding to VEGF receptors (VEGFR), it activates a series of intracellular signaling pathways that promote:

● Formation of new blood vessels (angiogenesis)

● Increased vascular permeability

● Proliferation and migration of endothelial cells

Within the tumor microenvironment, cancer cells often secrete large amounts of VEGF, enabling them to gain a “blood supply advantage,” which supports:

● Rapid tumor growth

● Metastatic spread

● Resistance to radiotherapy and chemotherapy

Therefore, blocking the VEGF signaling pathway is equivalent to cutting off the tumor’s “nutrient supply line,” making it a critical strategy in anticancer therapy.

II. Core Mechanisms of VEGF-Targeted Drugs

VEGF-targeted therapies exert antitumor effects mainly through three major mechanisms:

1️⃣ Ligand Neutralization

These drugs directly bind to VEGF molecules, preventing them from interacting with VEGFR and thereby blocking signal transduction at its source.

Key effects include:

● Inhibition of new blood vessel formation

● Reduction of tumor blood supply

● Induction of tumor hypoxia and necrosis

Representative drugs:

● Bevacizumab

● Ranibizumab

Among them, Bevacizumab was one of the earliest widely used anti-VEGF monoclonal antibodies and has been applied in the treatment of multiple cancers such as colorectal cancer, lung cancer, and renal cell carcinoma.

2️⃣ Inhibition of VEGFR Tyrosine Kinase Activity (VEGFR TKIs)

After VEGF binds to its receptor, the receptor’s tyrosine kinase domain becomes activated, triggering downstream signaling pathways such as:

● The MAPK pathway (promoting cell proliferation)

● The PI3K-AKT pathway (supporting cell survival and anti-apoptosis)

Small-molecule tyrosine kinase inhibitors (TKIs) can directly suppress VEGFR kinase activity, leading to:

● Inhibition of endothelial cell proliferation

● Suppression of tumor vascular network formation

● Multi-target inhibition (e.g., PDGFR, KIT)

Representative drugs include:

● Sunitinib

● Sorafenib

● Axitinib

These agents are characterized by oral administration and broad target inhibition, and they are commonly used in renal cell carcinoma and hepatocellular carcinoma.

3️⃣ VEGF Trap Mechanism

Certain fusion proteins function as “decoy receptors” with high affinity for VEGF, capturing VEGF molecules and preventing them from activating genuine VEGFR.

Typical drug:

● Aflibercept

Mechanistic features include:

● Binding simultaneously to VEGF-A, VEGF-B, and PlGF

● Inhibiting a broader spectrum of angiogenic signals

● Enhancing anti-angiogenic efficacy

This mechanism has shown important clinical value in the treatment of colorectal cancer and ophthalmic conditions such as macular degeneration.

III. Tumor Microenvironment Remodeling Induced by VEGF Inhibition

VEGF-targeted therapy not only suppresses tumor angiogenesis but also induces significant remodeling of the tumor microenvironment. For example, inhibition of abnormal blood vessel formation can promote “vessel normalization,” improving blood perfusion and enhancing the delivery of chemotherapeutic agents into tumor tissues. Meanwhile, VEGF inhibition can reduce tumor interstitial pressure, improve local oxygen supply, and mitigate hypoxia-induced drug resistance.

Furthermore, blocking VEGF signaling may modulate tumor-associated immunosuppressive environments, enhance immune cell infiltration, and strengthen antitumor immune responses. As a result, VEGF-targeted drugs are frequently used in combination therapy regimens, particularly alongside immune checkpoint inhibitors such as PD-1/PD-L1 inhibitors, to further improve overall treatment outcomes.

IV. Conclusion

Through multiple mechanisms—including neutralizing VEGF ligands, inhibiting VEGFR tyrosine kinase activity, and trapping VEGF signaling molecules—VEGF-targeted drugs effectively suppress tumor angiogenesis and have become an essential component of modern precision oncology.

With the continued advancement of combination immunotherapy and personalized medicine, the VEGF signaling pathway is expected to remain a key focus in future drug development and clinical cancer treatment strategies.