The immunotherapy drug Blinatumomab has shown to be an effective treatment for children and young adults with relapsed B-cell acute lymphoblastic leukaemia in a clinical trial led by the Children’s Oncology Group, part of the National Cancer Institute USA, and presented at the annual meeting at the American Society of Haematology.

The drug has shown to be more effective and less toxic than standard chemotherapy, with fewer severe side effects, longer survival, higher rates of undetectable residual disease, and more likely to proceed to a stem cell transplant. It works by binding CD19, a protein expressed on the surface of B-ALL cells, and CD3, an antigen expressed on T cells, to aid T cells in recognising the cancer cells and killing them by bringing them closer together.

Treatment for relapsed B-Cell acute lymphoblastic leukaemia (B-ALL) includes four to six weeks of chemotherapy. After this reinduction phase, patients typically undergo additional intensive chemotherapy or consolidation treatment. For half of the patients, a haematopoietic stem cell transplant is considered the best treatment depending on factors such as whether relapse occurred during initial treatment or shortly after it was completed. Chemotherapy can cause severe side effects in some patients and can sometimes be ineffective in reducing leukaemia levels enough for transplant, leading to a delayed or refused transplant. With longer waiting times for a transplant, patients are at an increased risk of cancer reoccurrence.

208 children and young adults aged 1-30 with relapsed B-ALL were randomly assigned to receive either two rounds of intensive chemotherapy or two 4-week rounds of treatment with the drug before proceeding to a transplant.

The blinatumomab group showed higher rates of overall 2-year disease-free survival and higher rates of overall survival at nearly 80%. There were fewer side effects, a higher rate of undetectable residual disease, and a higher rate of proceeding to stem cell transplant.

Blinatumomab has been approved by the U.S. Food and Drug Administration (FDA) and has been granted accelerated approval to the drug for some adults and children that are currently undergoing treatment for B-ALL. Future studies will combine blinatumomab with other immunotherapy drugs to investigate its effect on newly diagnosed B-ALL, rather than relapsed.

The results from this trial are promising and reinforce the important role that federally funded clinical trials in the US play in developing more effective treatments for children with cancer.