Research autopsies reveal how incurable skin cancer resists treatment

Research conducted at UCLH has discovered how some skin cancers stop responding to treatment at the end of life.

Scientists hope that this new information about melanoma’s resistance to current treatments will ultimately deliver new treatments which give people with advanced cancer more time with their loved ones.

Lead investigator of the PEACE study at UCL, Dr Mariam Jamal-Hanjani, said: “These results present the most detailed picture yet of what melanoma looks like at the final stages of life. We can now see how the cancer evolves to spread to the brain and the liver, and how it can beat the most common treatment currently available for people with advanced disease.

“I am in awe of the people who have taken part in the PEACE study. Faced with the life-altering news of a terminal cancer diagnosis, they have shown huge courage by deciding to help science after their death in the hope that this will benefit future generations of patients.

“We now have a huge opportunity to look for new ways to treat advanced cancer. I’m excited about the prospect of more people with cancer having the precious gift of a longer life thanks to research.”

An in-depth analysis of 14 patients who died from incurable melanoma has revealed that changes to the order, structure and number of copies of tumour DNA could cause some skin cancers to resist treatment. These changes also explain how melanoma can spread to other parts of the body.

The research, published in the journal Cancer Discovery, was carried out at the Francis Crick Institute, UCL and The Royal Marsden, with research autopsies carried out soon after death at UCLH and Guys and St Thomas’ mortuaries.

The research is part of the Cancer Research UK-funded PEACE study, which is shedding light on the final stages of life with cancer by analysing tumour samples taken from autopsies with informed consent.

Additional funding for this research was provided by Melanoma Research Alliance, The Royal Marsden Cancer Charity and Rosetrees Trust.

Many people with advanced cancers have had previous treatment which wasn’t successful because the cancer found ways to overcome it. The findings have been welcomed by relatives of people who consented to take part in the PEACE study, to help others who are facing the emotional and physical pain of an advanced cancer diagnosis.

In the study, the scientists took 573 samples from 387 tumours from 14 patients with advanced melanoma.

All of the patients in the study had been treated with immune checkpoint inhibitor (ICI) drugs, which help the immune system to recognise and attack cancer cells. In all 14 patients, ICI drugs had stopped working by the time of their deaths.

The scientists read the genetic code of individual cells within the tumour samples, looking for patterns in how the code changed when the tumours spread and resisted treatment.

They found that 11 out of the 14 patients in the study had lost functioning genes that enable ICI drugs to help the immune system recognise and attack the cancer. This loss occurs because the cancer can either make multiple copies of defective versions of the genes, or use circular rings of DNA from outside the chromosome (called extrachromosomal DNA) to override normal copies of the genes.    

To date, this is the largest study of its kind to find out in detail the changes that occur within melanoma tumours at the final stages of life. So far, almost 400 patients have consented to the PEACE study and the scientists have performed over 230 autopsies. The researchers involved are currently analysing samples from people who died from other types of incurable cancer, to find out how cancers spread and why they stop responding to treatment.

Image credit: Francis Crick Institute. Image is from the PEACE study demonstrating the atypical, discohesive, plasmacytoid cells characteristic of metastatic melanoma.