American scientists have succeeded in genetically modifying the immune systems of three cancer patients using Crispr genetic scissors, without creating any side effects. A first for this tool which is revolutionizing biomedical research.
These long-awaited results from a first clinical trial were published Thursday in the journal Science . They are only a very preliminary step and do not prove that Crispr can cure cancer, but show that the technology is, until proven otherwise, non-toxic. Researchers at the University of Pennsylvania (Penn) used Crispr, a molecular mechanism discovered in the early 2010s, to suppress three genes from certain cells in their patients' immune systems, so that these cells begin to recognize tumors, who otherwise are expert at growing incognito in the body.
Helping the immune system fight cancer
This technique belongs to the large category of treatments called immunotherapy, which has proven its effectiveness over the past decade: it helps the immune system to do the job it is supposed to do against cancer. It is often complementary to surgery, chemotherapy and radiotherapy, the other pillars of the anti-cancer arsenal.
Immunotherapy, in particular CAR T therapy, "has proven to be remarkable for patients who no longer have any options," said Edward Stadtmauer, a doctor at the University of Pennsylvania and responsible for this trial. . "Unfortunately, even with this technology, some patients do not see improvement," he says.
No serious side effects
Penn researchers recruited three of these patients. They took their T cells, a type of white blood cell, and then used Crispr scissors to remove genes that prevented them from doing their job of recognizing tumors. Then the genetically modified immune cells were reinjected into the patients. Nine months later, these cells were still there and without causing any serious side effects, which "proves the principle," according to Edward Stadtmauer. In the case of one patient, the duration was even a year, said the doctor.
"The big question that this study does not answer is whether cells modified by Crispr are effective against advanced cancers," write two researchers including the co-discoverer of Crispr, Jennifer Doudna, in a separate article published by Science . "All we can say is that we are able to make the genetic modification and reinject the cells safely," insists Edward Stadtmauer.
The patients' cancers have actually progressed, he told AFP. But these results demonstrate the value of Crispr, already used experimentally for other diseases, for example to treat people with blood diseases. Whatever happens, Crispr scissors are confirmed as "a revolutionary technique," says Dr. Stadtmauer. Many more studies will be announced in 2020 against cancer, he said.
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