Understanding Avastin and Its Role in Cancer Treatment

March 5, 2024

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Cancer remains one of the leading causes of death globally, with an estimated 10 million cancer-related deaths in 2020 alone. Fortunately, advances in cancer research have led to new and improved treatment options that can significantly improve outcomes for many patients. The mainstay treatments for cancer include surgery, chemotherapy, radiation therapy, and, more recently, immunotherapy and targeted therapies.

Avastin (bevacizumab) is one such targeted therapy that has transformed treatment for several advanced and metastatic cancers. But what exactly is Avastin, and how does it work? As a vascular endothelial growth factor (VEGF) inhibitor, Avastin has a unique mechanism of action compared to traditional chemotherapy or emerging immunotherapies.

This article provides an overview of Avastin, how it functions as a targeted therapy, key differences from immunotherapy, as well as some commonly asked questions about using Avastin for cancer treatment.

Avastin: Drug Classification and Function

Avastin (bevacizumab) is a humanized monoclonal antibody that inhibits angiogenesis by blocking vascular endothelial growth factor A (VEGF-A). VEGF-A plays a key role in the growth of new blood vessels, and increased signaling through this pathway is critical for solid tumor growth and metastasis.

By binding VEGF-A, Avastin essentially “chokes” the tumor’s blood supply, preventing further expansion of the vascular network that feeds tumor progression. It is the first anti-angiogenic therapy approved by the U.S. Food and Drug Administration (FDA) for treating various metastatic cancers.

Is Avastin an Immunotherapy?

No, Avastin is not an immunotherapy. While monoclonal antibodies like Avastin are sometimes classified under immunotherapy, Avastin does not stimulate the body’s immune defenses against cancer.

Instead, it is a targeted therapy that directly interferes with specific molecules and pathways involved in tumor growth and progression. The key difference is it does not engage immune cell function to attack the cancer.

Comparing Avastin to Immunotherapy

Immunotherapy leverages the immune system’s innate ability to recognize and destroy cancer cells, “taking the brakes off” immunosuppressive mechanisms that otherwise allow tumors to evade detection.

Checkpoint inhibitor immunotherapies like Keytruda (pembrolizumab) and Opdivo (nivolumab) block signals on immune T-cells that dampen anti-cancer responses, while CAR T-cell therapy involves engineering a patient’s T-cells to better recognize tumor cells.

In contrast, Avastin directly binds free VEGF-A to prevent signaling through VEGF receptors (VEGFRs) on vascular endothelial cells. This cuts off the tumor’s supply line of oxygen and nutrients carried by blood vessels, thereby slowing its unchecked growth and spread.

So while immunotherapy leverages general immune stimulation, Avastin has a precisely targeted effect on the VEGF angiogenesis pathway. Both can be powerful strategies, and may even have synergistic effects when used together in some contexts (see FAQ section).

Zirabev (Ziv-aflibercept) and MVAst: Understanding Similar Drugs

Alongside Avastin, there are a couple other drugs with similar mechanisms worth addressing briefly.

Zirabev (Ziv-aflibercept)

Like Avastin, Zirabev (ziv-aflibercept) is an anti-angiogenic agent that inhibits tumor vascularization by blocking VEGF signaling. Specifically, Zirabev binds not only VEGF-A like Avastin but also VEGF-B and PlGF (placenta growth factor).

So while quite similar in function, Zirabev may have slightly different therapeutic applications. But importantly, Zirabev is also not an immunotherapy.

MVAst (mirvetuximab soravtansine)

MVAst is an antibody-drug conjugate (ADC) combines targeting capacity of an antibody with anti-cancer activity of a chemotherapy agent. Early data suggests it shows promise for treating certain ovarian, lung and other cancers.

However, whether MVAst should be considered immunotherapy, chemotherapy, or targeted therapy is still under evaluation given its unique design. Like Avastin though, its mechanism does not involve general immune stimulation.

Frequently Asked Questions

What is the difference between Avastin and immunotherapy?

The key difference is Avastin is a targeted therapy that specifically blocks VEGF signaling to cut off blood supply to the tumor, while immunotherapy stimulates the immune system to attack cancer cells more broadly.

Can Avastin be used with immunotherapy?

Yes, there is emerging evidence that combining Avastin with immunotherapies like PD-1 inhibitors may improve outcomes for certain metastatic cancers. However, combination therapy should only be undertaken under guidance of your oncologist.

Is Zirabev the same as Avastin?

While Zirabev and Avastin are both anti-VEGF monoclonal antibodies used as anti-angiogenic agents, Zirabev binds VEGF-A along with other targets like VEGF-B and PlGF. So their therapeutic applications may differ somewhat when treating cancer.

What is MVAst, and how does it work?

MVAst is an investigational antibody-drug conjugate, but whether it qualifies as immunotherapy, chemotherapy, or targeted therapy is still under study. Its mechanism does involve antibody-directed targeting of tumor cells like Avastin though.

Where can I learn more about treatment options for my specific cancer type?

Reliable resources like the National Cancer Institute, American Cancer Society, and patient advocacy groups have detailed information on various cancer types and emerging treatments. But for personalized guidance, consulting your oncologist is critical.


  • Avastin (bevacizumab) is a pioneering targeted therapy and VEGF inhibitor used to treat certain metastatic cancers
  • It is not considered an immunotherapy as it does not stimulate anti-cancer immune responses
  • Avastin can be combined with some immunotherapies, but this should only be done under medical guidance
  • Similar drugs like Zirabev also inhibit VEGF signaling but may differ in therapeutic applications from Avastin
  • MVAst is an emerging antibody-drug conjugate, but whether immunotherapy or targeted therapy is still under evaluation
  • Accurate information is key, so consult a healthcare professional to understand your specific treatment landscape
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