Prepared by: Prof. Dr. Younis Abdul Redha Al-Khafaji
Introduction:
In the world of modern medicine—where discoveries unfold rapidly and disciplines increasingly overlap—an idea has emerged that may, at first glance, seem paradoxical or even alarming: using viruses, long regarded as humanity’s enemies, as a treatment for one of the deadliest diseases of our time—cancer. Yet what appears to be a contradiction is, in fact, a remarkable example of human ingenuity in harnessing nature for our benefit.
Since the early 20th century, scientists observed that some cancer patients experienced temporary improvement after contracting viral infections. This observation sparked the pursuit of “oncolytic viruses”, leading to the development of what is now known as Oncolytic Virotherapy.
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What is Oncolytic Virotherapy?
Oncolytic virotherapy is a form of biological therapy that uses genetically engineered or carefully selected viruses to specifically target and destroy cancer cells—without harming healthy cells. These viruses rely on their natural ability to invade and replicate within cells, but they are modified so that they:
• Selectively target cancer cells, exploiting unique features of these cells such as weak immune defenses or overactive growth pathways.
• Lose their ability to infect normal cells, making them relatively safe for therapeutic use.
• Stimulate the immune system to recognize and attack the tumor, adding an immune-based dimension to the treatment.
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How Do These Viruses Work?
When the modified virus is injected into the tumor or bloodstream, it follows a specific process:
1. Attachment and Entry: The virus binds to receptors that are abundant on the surface of cancer cells and enters them.
2. Replication: Inside the cancer cell, the virus rapidly multiplies, exploiting the tumor’s favorable environment (such as a weak interferon response).
3. Lysis (Cell Explosion): After replication, the virus bursts the cancer cell open from within, releasing thousands of new viral particles that go on to infect nearby cancer cells.
4. Immune Activation: When the cells burst, they release their contents—including tumor antigens—which alert the immune system to attack the remaining cancer cells throughout the body. This process is known as the anti-tumor immune response.
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Examples of Viruses Used in Therapy
• T-VEC (Talimogene laherparepvec): A genetically modified herpes simplex virus (HSV-1) approved by the U.S. Food and Drug Administration (FDA) for treating advanced melanoma (skin cancer). It is injected directly into lesions and produces an immune-stimulating protein (GM-CSF).
• Adenoviruses: Engineered to target various cancers, including prostate and lung cancer.
• Measles Virus: Has shown promising results in clinical trials against ovarian cancer and multiple myeloma.
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Challenges and Future Prospects
Despite its enormous potential, oncolytic virotherapy still faces several challenges:
• Early immune response: The immune system may destroy the virus before it reaches the tumor.
• Delivery difficulties: It can be challenging to deliver the virus effectively to deep-seated or metastatic tumors.
• Tumor diversity: Genetic variability among tumors may reduce the effectiveness of certain viruses.
To overcome these hurdles, researchers are exploring:
• Combining virotherapy with immunotherapies, such as immune checkpoint inhibitors.
• Encapsulating viruses in nanomaterials to protect them as they travel through the body.
• Engineering “smart” viruses that respond to specific biological signals in the tumor microenvironment.
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Conclusion
The use of viruses to treat cancer is no longer science fiction—it is an emerging medical reality. This approach exemplifies how science can transform a “foe” into an “ally.” With ongoing advancements in genetic engineering and immunology, oncolytic virotherapy may soon become a cornerstone of cancer treatment protocols, offering new hope to millions of patients around the world.
Al-Mustaqbal University the First in Iraq