At only 14 weeks old, Layla Richards was diagnosed with Infant Acute Lymphoblastic Leukemia (ALL). Typically ALL is treated with chemotherapy, but it can be ineffective in those with aggressive forms of the disease, when cancer cells hide from or are resistant to drug therapy. Layla was treated conventionally for a few months, but wasn’t responding – doctors eventually told the parents the prognosis did not look good.
Thankfully, researchers from the Great Ormond Street Hospital (GOSH) and the UCL Institute of Child Health’s (ICH) were developing an experimental treatment that used gene therapy to treat aggressive cancers like Layla’s. Thus far, it had only been tested on laboratory mice, but the parents decided to go through with it, since it seemed to be their only option. GOSH’s ethical committee approved the treatment, and now Layla is miraculously in remission.
All that was used to treat Layla was a one milliliter infusion of genetically altered UCART19 cells. These are essentially T-cells gathered from the immune system of healthy donors, programmed to attack and destroy leukemia cancer cells. This type of gene-editing is quite different from traditional gene therapy – genes are usually added to cells’ DNA for treatment.
The technology at work is called transcription activator-like effector nuclease, or TALENS. TALENS is considered to be a “molecular scissor” because the enzyme permits scientists to cut off DNA strands at specific sequences. For Layla’s treatment, the GOSH team employed the scissor to shut off the genes in donated T-cells that normally brought about the foreign cells’ rejection when transplanted. These designer cells were also altered for protection against chemotherapeutic drugs – the researchers’ gene-snipping made the cells invisible.
One large drawback is that Layla’s existing immune system had to be completely destroyed for the therapy to work. Although at this point in time doctors have confirmed Layla’s leukemia to be gone, she still required a bone marrow transplant to re-establish her immune system.
Additionally, this only represents a single successful case, and it’s a little early in the game to call this treatment a cancer cure-all. “We have only used this treatment on one very strong little girl, and we have to be cautious about claiming that this will be a suitable treatment option for all children. But, this is a landmark in the use of new gene engineering technology and the effects for this child have been staggering. If replicated, it could represent a huge step forward in treating leukaemia and other cancers,” explains Professor Waseem Qasim, Professor of Cell and Gene Therapy at UCL ICH and Consultant Immunologist at GOSH.
The therapy isn’t supposed to be a permanent fix, either. It’s meant to act as a “bridge” to keep patients alive until a T-cell donor match is found. There have also not been any formal, long-term clinical trials using this technique – however, the researchers expect to conduct larger scale trials in early 2016.