Thursday April 30 2015
The treatment destroyed previously resistant cancerous cells
"Prostate cancer resistant to conventional treatment could be all but wiped out by a therapy that boosts the immune system," the Daily Mail reports. The therapy, as yet only used in mice, enabled chemotherapy to destroy cancer cells in mice with previously treatment-resistant prostate cancer.
Abnormal body cells will usually be recognised by the immune system and destroyed. However, the fact the cancers develop and progress, and can be resistant to treatment, shows that something is preventing these cells from being destroyed.
Previous study has suggested that immune cells called B cells (which make antibodies) may have a role in making prostate tumours resistant to chemotherapy. This mouse study further investigated this by looking at different ways to suppress these B cells, using immune therapy or genetic techniques. It found that once these B cells were blocked or removed, a chemotherapy drug (oxaliplatin) was then able to attack and destroy mouse prostate tumours.
The researchers have dubbed this approach "chemoimmunotherapy", as it combines chemotherapy with immunotherapy (having an effect on the immune cells).
It is too soon to know whether "chemoimmunotherapy" could be the answer for progressive and treatment-resistant cancer in humans – prostate or any other type of cancer.
However, this study could aid further understanding of how the immune system tackles cancer, potentially leading to new treatment approaches.
Where did the story come from?
The study was carried out by researchers from the University of California, Institute of Immunology in Berlin, Medical University of Vienna and the University of Veterinary Medicine in Vienna. There is no information about external funding.
The study was published as a letter in the peer-reviewed scientific journal Nature (letters are short reports of new research that are of potential interest to other researchers).
Media coverage was fair, but over-optimistic, about the results being applicable to humans. It is exaggerating the results of this very early stage study to suggest that advanced prostate cancer could be “"wiped out", as suggested by both the Daily Telegraph and the Daily Mail.
To its credit, the Mail’s headline made it clear that the experiment was in mice. The Telegraph also mentioned this, below its headline.
What kind of research was this?
This was a laboratory experiment using mice, exploring how the body’s immune system deals with cancer.
Abnormal body cells will usually be recognised by the immune system and destroyed. However, the fact the cancers develop and progress, and can be resistant to treatment, shows that something is preventing these cells from being destroyed. The possible reasons are poorly understood.
Previous research suggested that immune system cells, called B cells (which make antibodies), may be involved in making prostate cancer cells progress and become resistant to chemotherapy. As the researchers point out, although early prostate cancer responds well to chemotherapy, this is not the case with advanced or established tumours.
The researchers aimed to look at whether by disabling or blocking the B cells in mice, chemotherapy may be more successful in activating the immune system to fight the cancer. This would be an approach of combined chemotherapy and immunotherapy – known as chemoimmunotherapy.
What did the research involve?
The research used mouse models of metastatic prostate cancer that were resistant to the chemotherapy drug oxaliplatin, which is used in the treatment of aggressive prostate cancer in humans.
The researchers looked at different ways of suppressing the development or activity of the B cells that are thought to block the activity of chemotherapy drugs. They blocked or removed the B cells using immune-modulating drugs or genetic engineering techniques. Treated and untreated mice were then given oxaliplatin for a three-week period to look at the effects.
The researchers also investigated which are the crucial B cells that require elimination, including looking at human prostate cancer samples.
What were the basic results?
Researchers found that when the B cells were blocked or removed, the mice prostate tumours were successfully treated with oxaliplatin.
The researchers were able to identify the exact type of B cells that were responsible for blocking treatment, and these cells were also found in human prostate cancer samples resistant to chemotherapy.
How did the researchers interpret the results?
The researchers say in an accompanying press release that their findings call for clinical testing of "this novel therapeutic approach."
They also point out that in addition to prostate cancer, similar immunosuppressive B cells can be detected in other human cancers. They say this indicates that B cell-mediated immunosuppression might be the reason several other cancers do not respond to treatment, raising hopes that the combination of chemotherapy and immunotherapy could have broader applications for other cancers.
This study has built on the findings of previous research that has suggested B immune cells could have a role in making prostate tumours resistant to chemotherapy. This mouse study further investigated this by looking at different ways to suppress these B cells, using immune therapy or genetic techniques. It found that once these B cells were blocked or removed, chemotherapy was able to attack and destroy aggressive prostate cancer cells in mice.
The potential for a new chemoimmunotherapy treatment approach for cancer is promising. However, the study is still at a very early stage. While mice studies can give an indication of how cellular processes work and how a treatment may work in humans, they are only indications, as there are inherent differences between the species. It is often the case that diseases in genetically engineered mice differ in key ways from the same disease in humans, so we can’t say whether the results of this study would be the same for humans.
It is too soon to know whether suppressing the B immune cell response could be the answer for progressive and treatment-resistant cancer in humans – prostate or any other type of cancer. It is also not known whether a safe and effective new immunotherapy treatment for cancer could be developed on the back of these results. Other immunosuppressants can cause a wide range of side effects, so the benefits of this treatment approach could be outweighed by the risks.
However, this study could further understanding of how the immune system tackles cancer, potentially leading to new treatment approaches.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.