Phase II clinical trial: Testing a new therapy to treat children with relapsed/ refractory cancers and immune system over-activation conditions

Whilst research has helped to improve the survival of children with many cancers, for those where their cancer fails to respond to initial treatment plans (refractory cancer), or where the cancer comes back following treatment (relapse), further treatment strategies are often limited in their ability to cure these patients. Haemophagocytic lympho-histiocytosis (HLH) and Macrophage Activation Syndrome (MAS) are life-threatening conditions which can occur alongside cancer and infections in children. They are caused by an activation of the immune system which causes high-grade fever and a sepsis-like condition. Current treatment is with untargeted, immunosuppressive chemotherapy, but the outlook is extremely poor with 25-50% of children with this condition not surviving. New research is critically needed for these groups of children to provide better treatment options leading to a cure.

Dr Mussai’s previous research has shown that in HLH/MAS there is an expansion of immune cells which drive the disease. They have also observed a similar effect in a wide range of aggressive cancers where the cells stop the child’s immune system from effectively attacking the cancer. These cells are identified by a marker called CD33. A drug called gemtuzumab ozogamicin (GO) which is already used for childhood blood cancers, is known to specifically target CD33 to help eradicate cancer cells.

Dr Mussai’s team will conduct a small clinical study to test the activity of GO in treating children with HLH/MAS (10 patients) and relapsed/refractory cancer (10 patients). Patients will be given GO once a week for 3 weeks, and the research team will measure the reduction of the CD33+ immune cells in the blood. They will also collect data on improvement in survival of these patients and other markers of their disease. It is hoped that the research evidence collected through this study will endorse a new therapy option for children who otherwise have no other treatment options.