A potentially revolutionary therapy that trains the immune system to attack cancer has shown “extraordinary” results in early trials involving terminally ill patients.
In one study, 94% of participants with acute lymphoblastic leukaemia saw their symptoms vanish completely. Patients with other blood cancers saw response rates greater than 80%, with more than half experiencing complete remission.
The technique involves removing immune cells called T-cells from patients, tagging them “receptor” molecules that target cancer, and infusing them back in the body.
Scientists screened specially bred, genetically engineered mice for the targeting molecules, known as chimeric antigen receptors or Cars. Once attached to the T-cells, they reduce the chances of the cancer being able to shield itself from the immune system.
Lead scientist Prof Stanley Riddell, from the Fred Hutchinson Cancer Research Center in Seattle, US, said: “These are in patients that have failed everything. Most of the patients in our trial would be projected to have two to five months to live. This is extraordinary. This is unprecedented in medicine to be honest, to get response rates in this range in these very advanced patients.”
Prof Riddell, who was speaking at the American Association for the Advancement of Science (AAAS) annual meeting in Washington DC, described the results as a “potential paradigm shift” in cancer treatment.
So far, the technique has only been tried on patients with “liquid” blood cancers. Prof Riddell hopes to progress to patients with solid tumours, but points out that this will be challenging.
Meanwhile, a new study raises the prospect of vaccine-like treatments that protect against cancer for life.
Scientists identified and tracked rare immune sys-tem cells that could be programmed to keep cancer at bay over a period of many years.
The “stem memory” T-cells would keep patrolling the body looking out for enemy tumour cells. When any are encountered, they would be recognised and attacked.
Lead researcher Prof Chiara Bonini, from the University of Milan in Italy, said: “T-cells are a living drug, and in particular they have the potential to persist in our body for our whole lives.
“Some of these memory T-cells will persist through the entire life of the organism... Imagine translating this to cancer immunotherapy, to have memory T-cells that remember the cancer and are ready for it when it comes back.”
For such an approach to work, the memory T-cells would have to be primed by genetic modification to attack the target cancer.
Prof Bonini’s team studied 10 cancer patients who underwent bone marrow transplants and were infused with T-cells that were tagged so they could be tracked. Small numbers of the cells were still found to be circulating in the patients’ blood streams after 14 years.
Commenting on the study, British immunologist ProfDaniel Davis, from the University of Manchester, said: “These T-cells, the stem memory T-cells first identified in 2011, have stem cell-like properties and are thought to be important for long-lived immune responses. The implication is that infusing genetically modified versions of these particular T-cells ... could provide a long-lasting immune response against a person’s cancer.”
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