This is the so-called immune disease Severe Combined Immunodeficiency (SCID). Due to a DNA error in the blood stem cells, these patients do not make immune cells and the body cannot defend itself against infections. The developed stem cell gene therapy can correct this error in the DNA. “The repaired stem cells have subsequently grown into a well-functioning immune system in the patient’s body,” says Arjan Lankester, professor of Pediatrics and Stem Cell Transplantation. “The baby passed the treatment without any problems and the immune system responds well to the usual vaccinations for newborns.”

    Treatment with stem cells

    For the treatment, stem cells were collected from the baby three months after birth. A good version of the broken gene was then built into the DNA of these cells. A so-called lame virus was used for this. This virus was used as a wheelbarrow that puts the gene in the right place. Frank Staal, professor of Stem Cell Biology: “So the virus is really just the wheelbarrow that brings the gene to the right place.”

    The repaired cells were then returned to the patient. He was allowed to leave the hospital within a month. Staal and Lankester expect that the patient will be ‘cured for life’ with this one-off treatment.

    The Leiden researchers expect that the patient will be cured for life with this one-off treatment. Without treatment, children with SCID often die before their first year of life. “But the current treatment, namely stem cell transplantation, has a number of drawbacks. For example, a good donor is not always available and a transplant with cells from another person also entails the necessary risks,” says Professor Lankester. “Because in stem cell gene therapy the patient is his or her own donor, we circumvent these problems.”

    LUMC is a pioneer in the field of stem cell gene therapy

    The LUMC is one of the few hospitals in the Netherlands that has a license to make genetically modified cell products itself in a special laboratory. “This means that we are not dependent on the pharmaceutical industry, which means that we can somewhat limit the costs for the therapy,” says Staal.

    Still, stem cell gene therapy is ‘very expensive’. Staal: “Because the therapy is still being used in a research context, it costs the patient nothing. In the long term, the level of the price tag is still unclear.”

    The LUMC has been working on stem cell gene therapy for fifteen years. “The process had many ups and downs,” says Staal. It was an ’emotional moment’ when it appeared that the therapy was working. Lankester: “It is fantastic to see that we have now actually been able to help a patient.”

    Ultimately, the aim is to make this stem cell gene therapy available to patients across Europe. Lankester: “Our motto is: the cells travel, not the patient. In this way, patients and family, who are already having a hard time, do not have to move abroad for a few months. This is now sometimes the case for other forms of SCID.”

    Further research is needed to determine whether this groundbreaking therapy will become the new standard for SCID in the future.