Childhood cancer researcher of the year Lars Karlsson: “An award for the future”
Pediatrician Lars Karlsson, postdoctoral researcher at the University 91̽, is researching one of the most aggressive forms of childhood cancer, a type of brain tumor that still cannot be cured. For his work in developing innovative treatments, he is receiving the Swedish Childhood Cancer Fund’s award Childhood Cancer Researcher of the Year 2025.
“It is, of course, a great honor and very exciting. For me, it is a sign that people see the potential of modern immunotherapies in the treatment of solid tumors,” says Lars Karlsson, researcher at Sahlgrenska Center for Cancer Research (SCCR), The Institute of Clinical 91̽s.
CAR-T therapy involves reprogramming the immune system’s T cells (white blood cells) so that they can more effectively identify and fight cancer cells. The treatment has long been used against various forms of blood cancer, but research now shows that the technique could also work against solid tumors, including brain tumors.
Two years of full-time research at Stanford
Lars Karlsson became a certified specialist in pediatrics at Queen Silvia’s Children’s Hospital in 2023. For the past two years, he has been on leave from the Childhood Cancer Center to do full-time research in the United States. At Stanford University, he joined a research group led by Michelle Monje, a leading researcher in cancer neuroscience who is running a clinical trial on CAR-T therapy for children with pontine glioma.
Pontine glioma is a rare but aggressive brain tumor located in the brainstem. It most often affects children between the ages of four and eleven. The prognosis is grim. No child survives, and radiation prolongs life by only a few months. In Sweden, between eight and ten children are diagnosed each year.
One patient’s tumor disappeared completely
“It is a tragic course of disease. There have long been no ways to attack this, but now there are studies with positive results for some individuals who respond to the treatment,” says Lars Karlsson.
For one patient in the study, a 20-year-old American who was diagnosed four years earlier, the tumor has completely disappeared after treatment.
“The fact that one patient appears to have responded to the treatment and that the tumor is completely gone is very promising, but most do not get this effect. The next challenge is to find out why some respond and others do not, and what we can do to improve the treatment.”
A side effect that research has shown is that there may be an increased risk of bleeding in the tumor in connection with CAR-T therapy. Lars Karlsson has focused his research on how the tumor’s blood vessels could be influenced to prevent bleeding and possibly also improve the effectiveness of treatment.
“It is still early, but we are beginning to understand the mechanisms. In five years, I believe we will have come a long way with this.”
“A brave researcher”
What does it mean to you to be brave as a researcher?
“I do not see it that way. I have always thought that it is generally good to dare to take some risks. This is quite a new field of research. For better or worse, you do not feel part of the mainstream when working on something that not many others are researching. Of course, you may stand out.”
After two years in the United States, the family has now returned home and Lars Karlsson will continue his research at The Institute of Clinical 91̽s at the University 91̽ together with Helena Carén and Jonas Nilsson, while also working as a physician at the Childhood Cancer Center. Not letting go of the clinical side, working with colleagues and patients in the ward and clinic, is important to him.
“Working at the children’s hospital is, of course, close to my heart. Partly because working with children who have cancer feels meaningful, and partly because it is a university hospital where research can be conducted alongside clinical work.”
Researching from the top down
Lars Karlsson emphasizes that it is important to conduct research based on real-life conditions.
“I find that researchers with a biological background often start with a protein. They work from the bottom up. Clinical researchers, on the other hand, often start with the patient, from the top down. Both perspectives are important, and I believe we have much to gain by working together to achieve a holistic perspective.”
According to Lars Karlsson, the conditions at the Childhood Cancer Center are good for being at the forefront and applying the latest advances in pediatric oncology. He explains that the clinic has weekly meetings with the other childhood cancer centers in Sweden to discuss patients and treatments. The children’s hospital also houses Sweden’s only ATMP center for children, a network for sharing knowledge and promoting clinical research in cell and gene therapy.
“There are also Nordic, European, and other international networks to stay updated on changing practices and new treatments.”
A new era in cancer research
It will still take time before it is possible to successfully treat pontine glioma with CAR-T therapy, but Lars Karlsson sees the award from the Swedish Childhood Cancer Fund as recognition that the field is worth investing in.
“It is an award for the future, one could say. And it feels hopeful that there is expertise and willingness to build this up here at home as well,” he says, referring in part to the work with modern cell therapies taking place at Sahlgrenska University Hospital’s ATMP center and new national ATMP initiatives such as the newly established CCRM Nordic, GoCo West.
“We are stepping into a new era, and there is expertise to conduct research and develop new cell therapies. And it is positive that many around me can do this so that we can work together.”
Text: Sahlgrenska University Hospital
Through his work in an internationally leading research group in cancer neuroscience, Lars has been part of exploring new treatment methods where immunotherapy with CAR-T cells appears particularly promising.
He combines innovative techniques with carefully built sample collections and collected data, strengthening the foundation for new research advances. Lars has established strong collaborations, both nationally and internationally, and the results so far offer new hope for the treatment of these severe brain tumors.
For his promising work and courage with new, bold approaches in the treatment of incurable brain tumors in children, Lars Karlsson is awarded the Swedish Childhood Cancer Fund’s prize Childhood Cancer Researcher of the Year.
The award Childhood Cancer Researcher of the Year
The award was established by the Swedish Childhood Cancer Fund in 2024 to highlight a young and promising researcher in the field of childhood cancer. A researcher whose work leads to discoveries that have or may come to play a major role in research and care of children with cancer.
“Through the award Childhood Cancer Researcher of the Year, we want to increase knowledge about what childhood cancer researchers do and show how their research helps increase survival and improve quality of life for children with cancer,” says Britt-Marie Frost, director of research at the Swedish Childhood Cancer Fund.
