Humoral and Cellular Immunotherapy in ALL in Children, Adolescents, and Young Adults

Although the event-free survival for children and adolescents with acute lymphoblastic leukemia (ALL) has dramatically improved over the past half century, it has plateaued over the past decade. Children and adolescents with refractory/relapsed ALL continue to have a dismal prognosis with hematopoietic stem cell transplant being their most viable option for cure. There is an obvious need for the development of novel agents to further enhance overall outcomes. In this review we focus on the development of humoral and cellular immunotherapeutic agents in the treatment of childhood, adolescent, and young adult ALL. Immunotherapy in various forms has shown immense promise. To date we have seen numerous safety studies using monoclonal antibody therapy, antibody conjugates, bispecific T cell and bispecific natural killer (NK) cell antibodies and genetically reengineered T and NK cells expressing targeted chimeric antigen receptors. Initial success has been found with the anti-CD20 monoclonal antibodies followed by promising results using anti-CD22 and anti-CD19 therapies alone or in combination. Genetic modification of T and NK cells to express targeted chimeric antigen receptors offers a novel immunotherapy option that demonstrates enhanced cytotoxicity in otherwise resistant tumor cells. There is great potential to combine immunotherapies to further improve overall cure rates in children, adolescents, and young adults with poor-risk ALL. A number of humoral and cellular immunotherapy strategies have been investigated and found to be effective, safe, and well tolerated. Ideally, the targeted approach of immunotherapy will result in an overall decrease in toxicities experienced by patients. Future studies are required to determine when in the course of treatment with humoral and cellular therapy will have the safest and optimal effect in ALL.