Elephants and cancer: getting it backwards

One News had a story tonight about elephants. This is how it starts

NZ anchor: An American researcher thinks he may have come up with a new weapon in the fight against cancer, inspired by a trip to the zoo. He remembered that elephants almost never get cancer and wondered whether what protects them could also help us.

US reporter: Elephants have survived 55 million years on this earth. They’ve evolved to beat cancer, and they might just help us beat it too

That’s a nice story, but it’s basically backwards from the more-plausible story in Nature News, and the (open-access) paper in JAMA.

The distinctive feature of elephant blood, according to either version of the story, is that elephants have many more copies of the tumour-suppressor gene p53. This gene makes a key protein in the mechanism that causes cells with DNA damage to kill themselves rather than reproducing and turning into tumours.  A large proportion of tumours have mutations in p53, and people who inherit a damaged copy of the gene tend to develop cancer (including some unusual forms) early in life.  We’ve known about p53 for a long time — decades — so while it is a target for drug development, it isn’t by any means a new target.  We haven’t got far with it because it’s hard to mimic the effect of a protein that acts inside the cell nucleus.

The story in Nature News is that the American researcher, Dr Jordan Schiffman, specialises in treating children with familial cancer, including ones who have inherited mutations in p53 (Li-Fraumeni syndrome). He heard a talk about elephants having many copies of p53. He then went to his local zoo to find out what the cancer rate was in elephants, and confirmed it was low.   This is important;  lots of people will tell you that sharks, for example, don’t get cancer, and that’s just not true.  Elephants, on the other hand, really do seem to have a surprisingly low rate of cancer.

Since elephants have a lot of cells and live a long time, you’d expect them to have a lot of chances to get cancer. Studying elephants makes sense as a way to find completely new ways of treating or preventing cancer. Unfortunately, it seems that a major reason elephants don’t get cancer  is that they have lots of redundant p53 genes, which isn’t a new treatment target. (Other reasons may be that they don’t smoke and they eat vegetarian diets.)

So, while it’s true that elephants have multiple copies of the p53 gene, everything else in the story is basically backwards. Looking for new cancer treatment targets in elephants is a good idea, but that’s isn’t quite what they did. The findings are good news for elephants but they are bad news for us; p53 isn’t a promising new treatment target, it’s one of the oldest ones we have.