The use of oncolytic viruses to activate the immune system and help treat melanoma

Robert Andtbacka, MD, CM of the Huntsman Cancer Institute, Salt Lake City, UT discusses the use of oncolytic viruses at the 2016 World Congress on Cancers of the Skin (WCCS) and the Congress of the European Association of Dermato-Oncology (EADO) in Vienna, Austria. He begins by explaining that traditionally, vaccines for melanoma have not worked well and that is partly because we do not know which antigens are important to try and activate the immune system. This is, however, changing with oncolytic viruses, which are injected directly into the tumor. These viruses are often engineered to only replicate in tumour cells and not in normal cells. Once the oncolytic virus enters the tumor, they replicate inside the cell which leads to the lysis of the cell and the exposure of tumour associated antigens to the immune system. The immune system will then attack the melanoma at the injection site while also developing a memory to attack the melanoma at distant, non-injected sites. This allows the immune system to pick and chose which antigens are important to develop immunity. Prof. Andtbacka then goes on to discuss that data has been collected which proves that this does indeed work. The data shows that when the oncolytic virus is injected locally there is a strong activation of the immune system systemically in the patient’s body. This activation can be detected in the blood stream by looking at CD8 positive T-cells. When the T-cell receptors are looked at, we find that the antigens they are reacting against are melanoma antigens. He explains that there are recent studies in progress in which the activated T-cell receptors will be identified, augmented ex vivo and then transfered back into the patient to try and have a better responce.

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