Tests of a potentially revolutionary cancer therapy have had “extraordinary” results on terminally ill patients, scientists have revealed.
In one study, more than nine out of ten participants with a severe form of leukaemia saw their symptoms completely vanish.
Four out of five patients with some other blood cancers responded positively to the treatment and more than half ended up symptom free.
Lead scientist Professor Stanley Riddell, from the Fred Hutchinson Cancer Research Center in Seattle, US, said the results were among patients who were projected to have two to five months to live.
He said: “This is extraordinary. This is unprecedented in medicine to be honest, to get response rates in this range in these very advanced patients.”
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The technique involves removing immune cells called T-cells from patients, tagging them with “receptor” molecules that target cancer, and putting them back into the body in an infusion.
The targeting molecules, known as chimeric antigen receptors or Cars, came from specially bred genetically engineered mice.
Once attached to the T-cells, they reduce the ability of the cancer to shield itself from the body’s natural immune system.
Speaking at the American Association for the Advancement of Science (AAAS) annual meeting in Washington DC, Prof Riddell described the results as a “potential paradigm shift” in cancer treatment.
Much more work was required, he said, adding that it was not clear how long the symptom-free patients would remain in remission.
Prof Riddell hopes to try the therapy on patients suffering from cancers with solid tumours, but said they would present challenges.
Although the body’s natural immune system is geared to tackle cancer, it is often unable to. Sometimes, the body’s defences cannot recognise cancer cells or they find ingenious ways to mask their identity.
In the most promising of Prof Riddell’s studies, around 35 patients with acute lymphoblastic leukaemia (ALL) were treated with the modified cells.
Almost all – 94% – went into complete remission. Being in remission is not the same as saying they are cured, because the symptoms can return.
Here, medics are urging caution. Dr Yvonne Doyle, from Public Health England, said: “It’s an important breakthrough, in that it’s a new technology that seems to have developed something innovative.
“However, it is on 30 patients who are at a very advanced stage of a particular cancer. So what we need to know is does this work in a wider situation?”
The treatment is similar to a technique used with success last year on Layla Richards, a one-year-old girl with ALL, by doctors at Great Ormond Street Hospital, who described the results as “staggering”.
More than 40 patients with lymphoma were also treated.
Remission rates of more than 50% and response rates of more than 80% were seen in one group with non-Hodgkin’s lymphoma. Patients with chronic lymphocyte leukaemia demonstrated similar results.
Seven of the ALL patients suffered an immune reaction to the treatment, called cytokine release syndrome (sCRS), so badly they needed intensive care. Two died. The scientists are now trying to find ways to reduce the risk from sCRS.
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