In a result that some immunologists are calling “revolutionary,” five cases of the severe autoimmune disease lupus have been sent into remission – and it’s all thanks to an experimental therapy previously known as a cancer treatment.
“We are very excited about these results,” said Georg Schett, a professor of rheumatology at Friedrich-Alexander University in Erlangen-Nuremberg and lead researcher on the project.
“Several other autoimmune diseases which are dependent on B cells and show autoantibodies may respond to this treatment,” he told The Guardian. “These include rheumatoid arthritis, myositis and systemic sclerosis… also diseases like multiple sclerosis may be very responsive to CAR T-cell treatment.”
But what is CAR T-cell therapy? It’s a fairly new treatment, usually used in the treatment of leukemia or lymphoma, which is both incredibly specialized and complex to administer, and almost astonishingly simple in concept. It's based on the miniature arms race that occurs between invading cancer cells and our body's own immune response to them: the immune system creates and deploys T-cells, a type of white blood cell which can hunt down and kill cancer cells in the body, while the cancer cells in turn can disguise themselves and hide from the incoming defenses.
Against that background, CAR T-cell therapy is basically a way to give those T-cells a helping hand – setting up a Special Forces squad, if you like. “[It] uses a patient's own T-cells, which are genetically modified in a lab, expanded into large numbers, and then reinfused back into the patient,” explained Chris McNamara, Consultant Hematologist at HCA Healthcare UK, in an explainer article on the treatment. “These new T-cells have a chimeric antigen receptor (CAR), which can identify protein on the surface of the cancer cells and destroy them.”
But the new breakthrough concerns lupus patients, not cancer patients. What prompted the researchers to make the leap from one to the other?
In lupus, as with other autoimmune diseases, the illness is caused by the immune system going haywire, sending out antibodies to attack healthy tissue as well as pathogens. It’s kind of the inverse of the cancer problem: it's not that the T-cells can't pick out the bad cells from the good ones now, but that B-cells – the other main type of white blood cell – are confusing good cells for bad.
But what if, instead of modifying T-cells to attack cancer cells, we could modify them to attack those misfiring B-cells? That’s what the team of researchers attempted – and according to their new paper, it was a huge success.
“CD19 CAR T-cell treatment does not only effectively deplete B-cells in patients with [lupus],” notes the paper, “but [it] also leads to drug-free remission of this systemic autoimmune disease.”
And even better: “the clinical effect of CAR T-cell treatment… remains present even after the patients reconstitute their B cells,” it adds. In fact, all five patients treated with CAR T-cell therapy have been in remission, and off medication, for between three and 17 months.
“That’s kind of unheard of,” Chris Wincup, a rheumatology and lupus specialist at King’s College London, who wasn’t involved in the study, told New Scientist. “This is incredibly exciting.”
While the researchers caution that it’s too soon to know how long the remissions will last, the result is already being seen by many as a cause for celebration – not only for people suffering from lupus but potentially for a wide range of autoimmune diseases.
“This is an excellent study,” said Rahul Roychoudhuri, an immunologist at the University of Cambridge, in the Guardian. “[It] promises to extend the scope of CAR T-cell therapy, which has thus far seen its major impact in the treatment of blood cancers, to autoimmune diseases like lupus which are in some patients poorly controlled with other medicines.”
“I am very excited at the prospects for this form of living therapy in indications beyond cancer.”
This study was published in the journal Nature.