Natural antibodies could combat devil facial tumour disease

For the past 20 years, Tasmanian devils have been under threat from devil facial tumour disease (DFTD) — a cancer that is spread from devil to devil via biting and has caused massive population declines.

Now, scientists believe they can stop the cancer using natural antibodies derived from a surprising source — the devil’s own immune system.

Writing in the journal Scientific Reports, Dr Beata Ujvari and colleagues explained that immunoglobulins such as IgG and IgM have been shown to induce antitumour cytotoxic activity in humans and animals. With this in mind, they set out to investigate the differences in molecules found in devils’ immune systems, comparing those that had DFTD and those that didn’t.

“We know from human and animal studies that certain natural antibodies are able to recognise and kill cancerous cells, so we wanted to see whether the presence of these molecules would also determine tumour development in Tasmanian devils,” said Dr Ujvari, from Deakin University’s Centre for Integrative Ecology.

The researchers’ analyses revealed that IgM and IgG expression levels, as well as IgM/IgG ratios, decreased with increasing devil age. Neither age, sex, IgM nor IgG expression levels affected devil DFTD status; however, devils with increased IgM relative to IgG expression levels had significantly lower DFTD prevalence.

“We can deduce, then, that devils with a higher natural antibody ratio are therefore less susceptible to the contagious cancer,” Dr Ujvari said.

Dr Ujvari said the results could potentially enable new treatment options, noting, “Antitumour vaccines that enhance the production of these natural antibodies, or direct treatment of the cancer with natural antibodies, could become a solution to help halt this disease.

“This process, known as ‘active immunotherapy’, is becoming more and more accepted in treating human cancers, and we think it could be the magic bullet in saving the Tasmanian devils from extinction.”

Image caption: Logistic relationship between Tasmanian devil DFTD status (1 = infected; 0 = uninfected) and IgM/IgG expression ratio.