Why Clone B20-4.1.1 is Essential for Preclinical TME Research

Vascular Endothelial Growth Factor (VEGF) is a primary driver of tumor angiogenesis. However, its role extends far beyond simply building new blood vessels to feed a growing tumor. VEGF is a potent immunosuppressor within the tumor microenvironment (TME), actively hindering dendritic cell maturation and blocking the infiltration of critical effector T-cells.

Because of this dual role, targeting VEGF has become a cornerstone of modern cancer therapy. For researchers modeling these therapies in immunocompetent mice, Anti-mouse VEGF Clone B20-4.1.1 is the gold standard.

What makes Clone B20-4.1.1 the preferred choice?

Originally developed by Genentech, B20-4.1.1 is a highly potent, cross-reactive monoclonal antibody that acts as the preclinical murine analog to the blockbuster drug Bevacizumab (Avastin). It effectively neutralizes VEGF-A, halting angiogenesis and helping to "normalize" the tumor vasculature.

The Power of Combinatorial Blockade with B20-4.1.1

Today, preclinical research rarely looks at anti-angiogenesis in a vacuum. Normalizing the tumor vasculature with B20-4.1.1 paves the way for immune cells to enter the tumor, making it the perfect partner for immune checkpoint blockades.

B20-4.1.1 has been frequently cited with the following highly synergistic clones in syngeneic mouse models:

• Anti-PD-1 (Clones 29F.1A12 & RMP1-14): Co-administering B20 with PD-1 blockade is currently one of the most heavily researched combinations in IO, designed to simultaneously normalize vasculature and reinvigorate exhausted CD8+ T-cells.
• Anti-CD8 (Clone 116-13.1): Frequently used alongside B20 to study the exact mechanics of T-cell trafficking and infiltration following VEGF blockade.
• Anti-CXCR3 (Clone CXCR3-173): Used in conjunction with B20-4.1.1 to evaluate how chemokine pathways assist in drawing T-cells past the endothelial barrier.
• Anti-DLL4 (Clone HMD4-2): For researchers focusing purely on angiogenesis, combining B20 with anti-DLL4 allows for a dual-blockade of both the VEGF and Notch pathways, completely starving the tumor of a functional vascular network.

Recent Citations using B20-4.1.1 in vivo

1) Immuno-Oncology Combination Therapy (February/March 2026)

Title: Digital spatial profiling reveals additive effects of triple therapy on tumor microenvironment: anti-PD-L1, anti-VEGF, and PARP inhibition in mouse models

Journal: Cancer Immunology, Immunotherapy (and PMC12882906)

How B20-4.1.1 was used: The researchers used B20-4.1.1 (dosed at 100 μg/mouse and 5 mg/kg i.p.) to block VEGF in immunocompetent murine models of colon adenocarcinoma (MC38) and ovarian cancer (HM-1). They found that adding B20-4.1.1 to their checkpoint blockade regimen significantly enhanced the infiltration of cytotoxic CD8+ T-cells into the tumors.

Other clones used in vivo: Anti-PD-L1 (Clone 10F.9G2): This was the primary checkpoint inhibitor used alongside B20-4.1.1

Isotype Controls: They utilized in vivo grade anti-mouse IgG2a and anti-mouse IgG.