Does treatment with pembrolizumab (a checkpoint inhibitor) provide additional benefit for various types of previously treated cancers in children and adolescents?

Cancer develops as a result of the uncontrolled growth of tumor cells, which can displace and destroy healthy cells. The term “solid tumors” is used when an organ or tissue is affected (e.g., the kidney). Malignant tumors can also affect the blood and the hematopoietic system—in this case, the condition is referred to as a malignant hematological disease. Among other cells, lymphocytes may be affected. Among other cells, lymphocytes—a subgroup of white blood cells that are part of the immune system—may be affected. One of the immune system’s tasks is to recognize and fight these altered cells in the body. However, through various mechanisms, cancer cells are able to protect themselves from detection by the immune system. Among other things, cancer cells can bind to the body’s immune cells and disable them, preventing the immune system from recognizing them and allowing the cancer cells to continue multiplying unchecked. Pembrolizumab is an immunotherapy drug that acts as an antibody to block this binding site on immune cells, known as the PD-1 receptor. In this way, the drug helps the immune system recognize and fight the cancer cells. The drug has already been approved for numerous forms of these malignant tumors and has been studied in various clinical trials. It is highly effective in some cases, allowing malignant diseases to be kept under control for a long time or even permanently, even when pembrolizumab is used as monotherapy. However, limited data on safety and efficacy are currently available for children and adolescents, particularly in situations where prior treatment has been administered but the disease is now active again (recurrence) or does not respond to standard therapy (refractory).

This Phase 1/2 study is investigating the efficacy and safety of pembrolizumab as monotherapy in children. Pembrolizumab is administered via infusion every 3 weeks for up to 2 years or until the disease progresses. The study is open-label, meaning that both medical staff and patients know which medication is being administered. Follow-up as part of this study will continue for up to 10 years, during which the efficacy of the therapy and the occurrence of side effects from the medication will be monitored. The key factor is whether or when the disease progresses again while on therapy. The primary endpoint of the study is the overall response rate.

Patients between 6 months, 3 years, or 12 years of age (depending on the type of cancer) and 18 years of age with a malignant solid tumor, skin cancer (melanoma), or lymphomas (Hodgkin’s and non-Hodgkin’s lymphoma) are eligible to participate in the study. There must be no involvement of the central nervous system.