Scientists are claiming “extraordinary” success with engineering immune cells to target a specific type of blood cancer in their first clinical trials.
Among several dozen patients who would typically have only had months to live, early experimental trials that used the immune system’s T-cells to target cancers had “extraordinary results”.
In one study, 94 per cent of participants with acute lymphoblastic leukaemia (ALL) saw symptoms vanish completely. Patients with other blood cancers had response rates greater than 80 per cent, and more than half experienced complete remission.
Speaking at the annual meeting for the American Association for the Advancement for Science (AAAS), researcher Stanley Riddell said: “This is unprecedented in medicine, to be honest, to get response rates in this range in these very advanced patients.”
To administer the T-cell therapy, doctors remove immune cells from patients, tagging them with “receptor” molecules that target a specific cancer, as other T-cells target the flu or infections. They then infuse the cells back in the body.
“There are reasons to be optimistic, there are reasons to be pessimistic,” said Mr. Riddell, of the Fred Hutchinson Cancer Research Centre in Washington State. He added that the researchers believe that lowering the dose of T-cells can reduce the risk of side-effects.
“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,” he said.
Even more hopeful was researcher Chiara Bonini, who said she has not seen remission rates like those of recent trials in over 15 years.
“This is really a revolution,” she said.
“T-cells are a living drug, and in particular they have the potential to persist in our body for our whole lives,” she added.
Ms. Bonini, a haematologist at San Raffaele University in Milan, said in another study researchers had tracked the presence of “memory” T-cells between two to 14 years after they had been introduced into cancer patients for whom bone marrow transplants had failed to work.
“T-cells are a living drug, and in particular they have the potential to persist in our body for our whole lives. This is a living therapy,” Mr. Riddell said. “When you put it in the cells will undergo expansion in vivo,” he said.
Tests so far have only targeted certain blood cancers, and the researchers acknowledged they needed to work on tumours and track how long patients would remain in remission. Cancer cells can sometimes hide unnoticed by the body’s defences, or simply overwhelm them and throw the immune system into overdrive.
T-cell therapy is often considered an option of last resort because reprogramming the immune system can come with dangerous side-effects, including cytokine release syndrome (sCRS) — and overload defence cells. Twenty patients suffered symptoms of fever, hypotension and neurotoxicity due to sCRS, and two died, but the researchers noted that chemotherapy had failed in all the patients who participated in the new trials. — © Guardian Newspapers Limited, 201