Novel leukaemia therapy aims to treat sick kids before time runs out
A decade ago, CAR T cell therapy changed the world of cancer treatment, offering a personalised approach to patients with blood cancers such as leukaemia.
But getting that specialised treatment to patients is costly and time-consuming. It can take up to two months to harvest a patient’s T cells and reprogram them into cancer-fighters — a non-starter for many young patients with aggressive cancer.
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These patients “don’t have months or years to live ... they have weeks,” Mayo Clinic Blood and Marrow Transplantation and Cellular Therapies director Dr Mohamed Kharfan-Dabaja said. He was not part of the new research.
A novel approach to CAR T (chimeric antigen receptor T cell) therapy aims to cut down that turnaround time significantly.
Instead of reprogramming each patient’s cells, researchers are testing the safety of using universal, or “off-the-shelf”, CAR T cells from other patients, preprogrammed to fight cancer. These cells are then tweaked further using another gene-modifying technology — CRISPR — to ensure they are not rejected by the patient’s own immune system.
Scientists at University College London tested the safety of the experimental approach in six children — mostly toddlers — with advanced leukaemia. The research was published last week in the journal Science Translational Medicine.
Conventional treatments, such as chemotherapy, had already failed in the six children in the study, a phase 1 clinical trial. The goal was to determine whether the new approach was safe. The scientists will determine whether it is effective in future, larger studies.
“These are very difficult children to treat,” study author, London’s Great Ormond St Hospital for Children cell and gene therapy professor Wassim Qasim said.
The goal of the new treatment approach is not necessarily curative - instead, it is to get patients into remission so that they are well enough for a bone marrow stem cell transplant.
The new approach is a “bridge to transplant,” doctors said.
While not said not involved with the trial, St Jude Children’s Research Hospital in Memphis Department of Bone Marrow Transplantation and Cellular Therapy head Dr Stephen Gottschalk called the new research “exciting”.
“If they’re not in remission before transplant, their likelihood of relapse is probably 80 per cent,” he said.
Modifying the harvested T cells with CRISPR — a genetic tool that can cut-and-paste bits of DNA — and then preparing them for use can take about 12 days, Qasim said.
For most patients, the wait may be even shorter — just the time needed to thaw the prepared frozen T cells.
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“If we want to make these treatments available worldwide, off-the-shelf is going to be the way to provide them,” Qasim said.
The “off-the-shelf” approach also ensures there are enough T cells for the treatment.
“These young children are so small that it’s very difficult actually to collect cells,” Gottschalk said.
None of the children in the trial experienced dangerous side effects from the experimental treatment.
One particular side effect associated with CAR T therapy is called a cytokine storm, and it can be deadly. It occurs when the body’s immune system goes haywire in response to the therapy.
While four of the children in the study ultimately died, it was not because of the treatment or a cytokine storm, but from their cancer. Two entered remission and remain alive and well 18 months following treatment, Qasim said.
University of Texas associate professor Dr Kris Mahadeo, who was not involved with the study, said the early results were encouraging.
“The idea is to get all of these children to live full lives,” Mahadeo said. “That’s the promise of what we’re working toward.”
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