Alyssa Tapley, a 13-year-old girl from Leicester, was the 1st patient to receive a novel gene-edited cell therapy after her condition was refractory to standard treatments. Immune cells (T cells) from a healthy donor were given to her by doctors at Great Ormond Street Hospital (GOSH), in a procedure developed with scientists at University College London Great Ormond Street Institute of Child Health (UCL-GOS ICH), however these were “reprogrammed” through a technique called base editing so that they could recognize, attach to, and kill cancerous T cells in her body.
Alyssa’s leukaemia was no longer detectable only 28 days post-treatment. She subsequently underwent another bone marrow transplant to reconstitute her immune system at GOSH Hospital.
What Is “Base-Edited Cell Therapy”?
Simply put: doctors remove immune cells from a healthy person; they then substitute a few letters in those cells’ genetic code (without breaking the DNA strand) and insert a “homing device” that enables those cells to destroy only cancer cells — leaving healthy ones intact.
Since the cells are from a donor and have been modified in a controlled manner, they turn into an “off-the-shelf” product — that is, they could potentially be available for a number of patients quite soon rather than having to prepare individual cells for each patient.
What’s Happening Now — and Why It Matters
As per a 2025 report from GOSH, Alyssa Tapley is 16 years old at present, and she is still the only individual to have undergone this base-edited cell therapy.
Her leukemia is still in remission, and she has been given the go-ahead for long-term follow-up outside the hospital. She is, according to reports, back to being with friends and family and thus showing that the treatment has given her a new lease of life.
The triumph here provides solace to the patients with the most severe types of hematological malignancies — especially those for whom chemotherapy or transplant has failed — as it demonstrates that such a novel treatment is indeed possible and, perhaps, could be more widely accessible in the future.
Words of Caution — It’s Still Early
This treatment was succeeded only on one patient that is why the scientists are not 100% sure that this therapy can soundingly effective for the rest of the other patients. Medical professionals and researchers should be attentive and continuously monitor for possible side effects, health issues, or even relapse.
Why This Is Hopeful for the Future
Alyssa’s example is a perfect demonstration that advanced gene-editing and immunotherapy techniques may turn the tables even on the most seemingly unresolvable cases of leukemia, i.e., those that don’t respond to chemo and transplant.
If the further clinical trials deliver positive outcomes, this could be the beginning of the end for the cell therapy shortage problem, as new ‘off-the-shelf’ cell therapy products could be the way forward.