German doctors achieve breakthrough in treating childhood cancer

Tengrinews.kz – A 17-year-old patient named Milo has become the first teenager in the world with a solid tumor in whom no living cancer cells are detectable after a new immune cell therapy.
According to the DW Telegram channel, the boy from Thuringia had been fighting cancer for almost ten years — initially a malignant kidney tumor. Later, despite surgery and chemotherapy, the tumors spread to his liver, spleen, lungs and brain.
His last chance was an experimental immune cell therapy carried out in Heidelberg, at the Hopp Children’s Tumor Center (Hopp-Kindertumorzentrum).
As senior physician and medical director for cell and gene therapy Christian Seitz told the Rheinische Post, Milo’s tumor cells were found to have a specific protein. This made it possible for doctors to “train” the patient’s own T cells so that they would recognize and destroy precisely these cancer cells.

“Immune cells were extracted from the teenager’s blood, genetically modified and then infused back into his body. On 2 July 2025, Milo received the infusion of modified T cells. Just 12 days later, the first tumor foci stopped being visible on MRI, and after 120 days no detectable living cancer cells remained in the body,” the report says.

Doctors emphasize that for pediatric oncology this is a completely pioneering development. Until now, cellular immune therapies had officially been used in children almost exclusively for leukemias. Treating solid tissue tumors in this way had not previously been done — it required a special authorization from the authorities for an individual therapeutic experiment.
Milo, who is passionate about downhill mountain biking, resumed training not long after the therapy. He is now planning to complete school and dreams of studying medicine in Heidelberg in order to become a doctor himself. Childhood cancer is relatively rare — about 2,000 new cases per year in Germany — but it remains the second most common cause of death among children and adolescents, ARD writes.
Many drugs and methods effective in adults work poorly in children, because pediatric tumors are biologically different and often have fewer mutations.