Two patients who received CAR-T gene therapy more than a decade ago are still in remission, the longest follow-up study of its kind has shown.
Researchers at the University of Pennsylvania, Philadelphia and Children's Hospital of Philadelphia found the patients were still in remission from the blood cancer they had been treated for, known as chronic lymphocytic leukaemia (CLL).
'This long-term remission is remarkable, and witnessing patients living cancer-free is a testament to the tremendous potency of this ''living drug'' that works effectively against cancer cells,' stated lead author Professor J Joseph Melenhorst.
CAR-T gene therapy involves extracting T-cells – immune system cells that are important in fighting against cancer cells – from a patient's blood. These T-cells are genetically engineered to have a gene that expresses, Chimeric Antigen Receptors (CARs), which will recognise targets on cancer cells and attack them. These engineered CAR-T cells are then infused into the patient to strengthen their immune response to cancer cells.
The study, published in the journal Nature, focused on the long-term monitoring of two patients who were part of the clinical trial for a CD19 CAR-T gene therapy. Subsequently, this was the first gene therapy for leukaemia approved by the US Food and Drug Administration (FDA), known as Kymriah in 2017 (see BioNews 916). It has been approved to treat certain types of lymphoma since 2018.
In 2010, both patients (Doug Olson and Bill Ludwig) showed complete remission, and this has now been sustained for more than a decade after treatment. Blood samples, taken and examined intermittently since 2010, showed that CAR-T cells could still be detected and were functional. By contrast, the cancer cells were found to be undetectable or highly suppressed within years of treatment.
'It could be that every last cancer cell was gone within three weeks of when we treated [the patient],' Professor Carl June – who is a pioneer in this experimental therapy, and one of the authors of this study – told a press briefing, as reported by IFL Science. 'Or it could be they keep coming up like whack-a-moles and get killed because these CAR-T cells are on patrol.'
He went on: 'I think basically all blood cancers will be treated with CAR-T cells over the next decade... because they're starting to move to frontline therapies, rather than end-of-the-line therapy as Doug Olson had back in 2010 when there was basically nothing else left in the toolbox. The big scientific challenge... is how to make this work in solid cancers. Solid cancers make up around 90 percent of all cancers.'