Boosting immune system helps tumour fight
pharmafile | August 21, 2013 | News story | Research and Development, Sales and Marketing | CRUK, Cancer, Iressa, Yervoy, immune system
Researchers have found that a key protein used to control immune function could help the body to attack tumours.
This is according to a new pre-clinical study published in the Nature Medicine journal, which the paper’s authors believe will lead to new drugs that target the protein involved so the immune system shrinks tumours without affecting healthy tissue.
“This pre-clinical study demonstrates proof of principle that using a drug to regulate the function of a special, immunosuppressive subset of so-called T-regulatory (Treg) cells safely controls tumour growth,” explains study leader Dr Wayne Hancock, of the division of transplant immunology at the Children’s Hospital of Philadelphia (CHOP).
The researchers bred mice which lacked a chemical needed for Tregs to work effectively. They then used a drug which produced the same effect in normal mice. Previous studies have shown that Tregs are important for suppressing immune activity and can block the immune system’s ability to attack cancer.
In both experiments, the shift in the immune system restricted the growth of a type of lung cancer. “It really moves the field along toward a potentially major, new cancer immunotherapy,” said Dr Hancock.
The discovery of these cells came when researchers worked on a subset of cells called Foxp3+ Tregs. It appears there is a way to reduce tumour growth without promoting autoimmunity if you target a Treg enzyme called p300.
Catharine Paddock, PhD, explains: “The protein Foxp3 plays a key role in controlling how Tregs behave, and p300 is the trigger. By deleting the gene that expresses p300, the researchers found Treg cells safely limited tumour growth in mice.”
Notably, the researchers also achieved the same effects on p300 and Tregs in mice by using a drug that inhibits p300 in normal mice.
Dr Hancock said he will pursue further investigations into targeting p300 in immunotherapy.
But the trials are yet to be conducted in humans, meaning any potential treatment coming from this early-stage discovery could still be a decade away.
Dr Emma Smith, from Cancer Research UK, said: “Turning the power of our immune system against cancer is a promising field of research and something scientists around the world, including our own, are studying.
“These findings go another step towards developing new treatments that act in this way, but the research is still at an early stage and we don’t know yet whether this approach will be safe or effective in people.”
Cancer vaccines
Several oncology drugs are already on the market which target the immune system, including the world’s first cancer ‘vaccine’ Provenge, made by Dendreon for prostate cancer in 2010, and more recently Bristol-Myers Squibb’s Yervoy, which is indicated to treat late-stage melanoma.
These drugs have been touted as potential blockbusters and represent a new way of treating cancer. In this new era of personalised oncology medicine, new drugs such as Roche’s Avastin or AstraZeneca’s Iressa target specific mutations and signals that are causing tumours to grow, but can only help a small proportion of patients with that particular mutation.
But drugs like Yervoy can potentially work on everyone as it ‘teaches’ the body’s immune system to attack the cancer. But these treatments come at a high cost, with Yervoy’s price tag around $120,000 in the US for a full course of treatment.
Ben Adams
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