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A pioneering treatment that edits healthy immune cells to fight cancer has shown promise for adults and children with a rare and aggressive form of leukemia that “seemed incurable”.
About two-thirds of patients with T-cell acute lymphoblastic leukemia (T-ALL) enrolled in clinical trials of the treatment — known as BE-CAR7 — are now disease-free.
BE-CAR7 was developed by scientists Great Ormond Street Hospital (O Lord) and University College London (UCL).
This is a highly advanced version of immunotherapy known as CAR T-cell treatment.
CAR T-cell therapy typically involves a doctor collection T cells From a patient.
They are then modified in a laboratory, with proteins called chimeric antigen receptors (CARs) placed on the surface to recognize and kill the cancer.
The immune cells are then put back into the patient’s bloodstream using a drip.
However, developing CAR T-cell therapy for leukemia developing from abnormal T cells has been challenging.
BE-CAR7 uses healthy T cells obtained from a donor to create an “off-the-shelf” version of this treatment.
This new process of modifying T cells is called base editing, and it allows them to work after chemotherapy, as well as deactivate them to prevent attacks against normal cells.
Base-editing is an improved version of the gene-editing tool Crispr, which earned its inventors nobel prize to chemistry in 2020, and can change single letters of the DNA code inside living cells.
A clinical trial explored whether BE-CAR7 could cure leukemia before a planned bone marrow transplant, in the hope that it might prevent the cancer from returning.
Nine children and two adults with T-ALL were treated as part of the study at Gosh and King’s College Hospital.
Now, about 64% are disease-free, with the first patients stopping treatment after three years.
More than eight in 10 (82%) achieved deep remission and were able to undergo stem cell transplant without disease.
side effectsAccording to the researchers, side effects, including low blood counts and rashes, were tolerable.
Wasim Kassim, Professor of Cell and Gene Therapy at UCL and Honorary Consultant Immunologist at GOSH, said: “We have previously shown promising results using precision genome editing for children with aggressive blood cancers and this large number of patients confirms the impact of this type of treatment.
“We have shown that universal or ‘off-the-shelf’ base-edited CAR T-cells can seek out and destroy very resistant cases of CD7+ leukemia.”
Dr. Rob Chiesa, study investigator and bone marrow transplant consultant at GOSH, said: “Although most children with T-cell leukemia will respond well to standard treatment, about 20% may not.
“These are patients who desperately need better options and this research offers hope for a better prognosis for everyone suffering from this rare but aggressive form of blood cancer.”
BE-CAR7 was first awarded to 13-year-old Alyssa Tapley from Leicester in 2022.
He was diagnosed with T-cell leukemia in May 2021 and did not respond to standard treatments.
Alyssa, now 16, said: “I chose to take part in the research because I felt that, even if it didn’t work for me, it might help others.
“Years later, we know it worked and I’m doing really well.”
Dr Deborah Yallop, consultant haematologist at King’s College Hospital, said: “We have seen impressive responses in curing previously incurable leukemia – this is a very powerful approach.”
Alyssa now hopes to become a research scientist.
“I did all the things you’re supposed to do as a teenager,” he said.
“I’ve gone sailing, spent time away from home for my Duke of Edinburgh award, but even going to school is something I dreamed of when I was sick.
“I’m not taking anything for granted.
“Next on my list is to learn to drive, but my ultimate goal is to become a research scientist and be part of the next big discovery that can help people like me.”
The results of the clinical trial have been published in the New England Journal of Medicine and presented at the 67th American Society of Hematology annual meeting in Florida.
Commenting on the findings, Dr Tania Dexter, senior medical officer at stem cell charity Anthony Nolan, said: “The study results are promising, with the majority of patients achieving levels of remission allowing them to receive stem cell transplants.
“Given that these patients had a low chance of survival before the trial, these results bring hope that such treatments will continue to advance and become available to more patients.
“Like any novel cellular therapy, this Phase 1 trial is only an early indication of the treatment’s effectiveness and safety, and more work must be done to determine its broader clinical application.
“Yet the results are encouraging and demonstrate recent leaps in technology that are allowing us to meet even greater challenges in the treatment of blood cancers and blood disorders.”