We recently heard that 91-year-old former US president Jimmy Carter’s melanomas that have spread to his brain and liver have disappeared.

Most people know that Mr Carter is extremely religious and although I am not disputing he may have received some upside help, especially with the initials 'JC', he also received some significant medical help.

That help was in the form of a rather new drug known as Keytruda with the more difficult name to pronounce Pembrolizumab, which is a monoclonal antibody that targets the activity of two specific chemicals that act as an invisible shield around tumour cells which allows the tumours to escape the detection by the immune system.

Basically the Keytruda disrupts this invisible shield effect and allows the immune system to recognise the tumours as being foreign and therefore attack the tumours.

A recent large study shows that Keytruda can shrink tumours by 90% in a third of patients. Another study of rather similar drugs Nivolumab and Ipillimumab, showed that 60% of patients had shrunk their tumours by a third.

It is important to also note that Mr Carter also received brain irradiation and had one of the tumours surgically removed from his liver.

The well-known Australian businessman Ron Walker also received Keytruda with great benefit. Interestingly I saw a patient a few weeks ago who had received Keytruda for transitional cell cancer that had attacked his kidneys and spread and again, he has received significant remission with this drug.

The only problem with Keytruda is it does cost around $10,000 per injection and some people need up to 10 injections for the effect.

Recently, the Australian Government approved Keytruda for specific indications on the PBS.