Cancer Fighting Viruses – the good guys

 

Oncolytic Immunotherapy uses oncolytic viruses are injected directly into tumors where they replicate inside tumor cells causing cell lysis ( replicates inside cancer cells and causes the cell to burst) and death.

 

This release intracellular proteins activating the innate immune system including sting and TLR pathway leading to antitumoral effects. The released tumor antigens are taken up by the antigen presenting cells which activate the T cells triggering an immediate immune response.

The T cells seek and destroy the cancer cells wherever in the body. Providing a systematic adaptive immune response- specific to a patient’s cancer.

This immune therapy is developed on a herpes simplex virus-derived platform and are armed with multiple genes including proteins intended to enhance cancer cell killing and promote an antitumoral immune response. These proteins contain- Anti-CTLA-4(antibody like molecule and co-stimulatory pathway activators that promote cancer killing and antitumoral response.

 

As compares with systematic delivered antibody-based response, direct delivery to these proteins to the tumor cells both reduce toxicity and increase efficacy   specifically when used with other anticancer agents – including immune checkpoint inhibitors.

Some disadvantages of other cancer treatments:

  1. Cancer therapy such as chemotherapy and radiotherapy usually damage our normal cells body cells
  2. Other therapies such as surgeries are not always accurate and thus might not remove the tumor completely and thus cancer redeveloped.

Why can our own body not detect the cancer cells?

Our body is unable at detecting cancer cells because cancer cells look our bodies normal cells to the immune system using viruses, we make our cancer cells visible.

Why are normal cells resistant to these viruses?

If the cell is attacked by the virus it produces interferon- which protects the cell and its neighboring cells. However, cancer cells are weak thus they cannot produce interferon- even if they are given interferon, they cannot respond to it.

Another way in which oncolytic viruses help kill cancer cells

Step1: Insertion of cancer cells in mouse #1

Step2: The mouse #1 develops a tumor

Step3: The oncolytic virus is injected in the mouse#1

Step 4: The tumor is cured

Step5: Isolate the spleen cells from the mice – these spleens contain immune cells

Step6: injection of the spleen cells into mouse#2 (note that no viruses are injected in      mouse#2)

Step7: Injection of tumor cells into mouse#2

Observation: the tumor can be induced as the mouse#2 has acquired immunity from the spleen cells of mouse#1 to protect itself from the tumor cells.

Further Research:

  • Scientists are researching more over how to increase the specificity of the virus.
  • Provide a faster immune response
  • Reduce Side effects
  • Growing them on an industrial scale

References

https://replimune.com/our-science/oncolytic-immunotherapy/

https://www.youtube.com/watch?v=nsoP4SPi2jY – Killing Cancer with Viruses: Patrick Lee at TEDx Halifax

https://www.youtube.com/watch?v=6tJJQgyso1I – oncolytic viral therapy

https://www.youtube.com/watch?v=xJvpDatBT4w – Institute of cancer research London

https://replimune.com/our-science/oncolytic-immunotherapy/

https://www.cancer.gov/news-events/cancer-currents-blog/2018/oncolytic-viruses-to-treat-cancer

 

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