Isaac Brownell, MD, PhD of the National Cancer Institute, Bethesda, MD discusses the virus associated with Merkel cell carcinoma and ongoing research into a potential vaccine for the disease during his attendance 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. Unlike in other skin cancers, Dr Brownell explains that Merkel cell carcinoma is associated with a virus, which may explain why the immune system is able to target so many of the tumors. Viruses express proteins which are not usually expressed in the body, which gives a natural target for the immune system. Because these tumors are driven by a virus and it is necessary for the viral proteins to be expressed, the tumor needs to figure out a way to protect itself from the immune detection of that viral protein, which may be another reason that checkpoint inhibitors are effective in Merkel cell carcinoma. The virus associated with Merkel cell carcinoma is abundant in the environment and can be found on most peoples skin and does not appear to cause any issues. During cancer, the virus is integrated into the host DNA and the virus proteins become mutated which drives tumor formation. Dr Brownell believes developing a vaccine against this virus would not likely be effective as there is not a strong correlation between infection and tumor formation. However, research into vaccines against the tumor formation are ongoing, with the aim to develop a vaccine specifically for patients with Merkel cell carcinoma, which would augment the immune response.