Australian researchers have discovered that removing copper from the blood can destroy some of the deadliest cancers that are resistant to immunotherapy using models of the disease.
Dr.Orazio Vittorio and his team from Children's Cancer Institute in Sydney and UNSW Sydney published the findings today in the journal Cancer Research.
While immunotherapy, a treatment that works through a patient's immune system to kill the cancers, has proven to be a breakthrough for many cancer patients, offering real hope and for some even a cure -- some cancers camouflage themselves from current immunotherapies by expressing the aptly titled Programmed Death Ligand or PD-L1.
It is known that cancer cells such as brain cancer "feed" on copper, often having up to six times the normal levels of the metal inside the tumor cells. Dr. Vittorio and colleagues, including Professor Maria Kavallaris AM, studied tumor samples from more than 90 patients with neuroblastoma and 90 patients with gliomas. Both these cancers have high mortality rates and to date have not responded well to cancer immunotherapy. Neuroblastoma accounts for 15% of total childhood cancer deaths and only 50% of patients with high-risk neuroblastoma patients survive their disease. Glioblastoma has the worst survival rate of all cancers, with only 5% of patients surviving 5 years past their diagnosis.
According to Dr. Vittorio, these two cancers express PD-L1 as a way to hide from the immune system, explaining why these two cancers are so deadly.
By looking at the human biopsies the researchers found a correlation between high levels of copper and increased expression of PD-L1. The researchers then showed for the first time that copper levels could control the expression of PD-L1 in cancer cells.
The researchers went on to use an analog of a drug, called TETA, which is currently used in the treatment of Wilson's Disease, which is a rare genetic disorder characterized by excess copper stored in various body tissues. They used this drug in animal models of neuroblastoma and glioblastoma to reduce the amount to copper in the tumor cells, leading to a reduction in the expression of PD-L1.
"When these mice were given immunotherapy there was a significant reduction in the size of their tumors," Dr. Vittorio said.
"Given that TETA is already in use in a number of clinical conditions and it is inexpensive and easy to manufacture, this may offer a viable treatment alternative for those cancers that are resistant to current immunotherapies."
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