Research in the past few years revealed how UV-light and the presence of papillomaviruses may lead to skin cancer. A recent study suggests that – surprisingly – HPV might be useful in preventing a type of the disease.
In 10 seconds? Immunity to certain strains of the Human Papillomavirus (HPV) may protect against Squamous Cell Carcinoma (SCC), the second most common form of skin cancer. This surprising discovery is especially good news for people with organ transplants. (Read the science)
So, why the surprise? Because we’ve learned that it’s our immune reaction to so-called beta-HPV that determines if we develop this type of skin cancer. The reaction is a result of UV light-exposure, i.e. spending too much time sunbathing or in the tanning salon. People who underwent organ transplant surgeries had to have their immune systems suppressed. This made them more susceptible to cancers resulting from viral infections, so the discovery gives us an idea of how to protect them and others. (Read the paper)
What’s the novelty here? The fact, that despite what we thought earlier, the presence of HPV is not enough to cause skin cancer. The authors of the recent paper found that when lab mice produced an immune response against their version of the Papilloma Virus, they did not develop SCC. Which means it’s not beta-HPV that opens the door to SCC in subjects with weakened immune systems. Rather, it’s the actual loss of immune function and the inability to resist the virus that increases the risk. (More on links between skin cancer and HPVs)
OK, but why is this significant? Because HPV is a so-called commensal virus, found on our skin and this is the first time we see that it can help ward off cancer – if there is immunity against it. This idea was backed up by scientists when they transplanted immune cells from healthy mice into immunosuppressed ones – making them resistant to skin cancer! (More on how UV can suppress the immune system)
Hang on, does this invalidate previous research? Not necessarily. Earlier research had established how ultraviolet radiation from sunlight could affect the immune system. It can, for example, suppress the adaptive cellular immune response, and thus contribute to the development of skin cancer by making the immune system unable to resist HPV. (Find out more)
How do we know this? Research was held back because papillomaviruses are ‘species-specific’. MumuPV1, the virus affecting mice – and allowing lab experiments - was discovered only recently. Once it was available, my team had found that it only caused skin warts in mice with a defective immune system, while not in healthy ones. But when healthy mice carrying the virus were exposed to UV light, they developed warts and SCC. So our earlier research had already established that UV caused defects in the immune system which made mice vulnerable to the papillomavirus. And this opened the the door for skin cancer. (Read more)
And what can we expect in the future? With the new research, scientists can turn their attention to creating immune cell-based vaccines. These, in turn, will be able to protect high-risk people from developing warts and skin cancers. The research can also contribute to making immune checkpoint inhibitor therapy - currently used for some skin cancers - more efficient.
How an HPV-vaccine killed off one woman’s skin cancer
Although we are still waiting for large scale clinical trials, an often-mentioned paper from 2018 details how treatment with an HPV vaccine cleared up Squamous Cell Carcinoma in a 97-year-old woman.
Because the size and the sheer number of her tumours, neither chemotherapy nor radiotherapy was a viable option for her, the clinic offered an experimental treatment on the understanding that it would do no harm.
A specialist injected an existing HPV vaccine (developed to prevent cervical, anal, vulvar and vaginal cancer) as an "off-label" treatment directly into the tumours of the patient.
According to the clinic and the case report, all of the tumours have disappeared over the 11 months-long treatment and they did not return.
(Psst, Ayushi distilled 10 research papers to save you 986.7 min)