Novel antibody-based therapies for acute lymphoblastic leukemia

A major breakthrough in the treatment of acute lymphoblastic leukemia (ALL) was the availability of targeted therapies targeting either specific transcripts, such as bcr-abl fusion protein by tyrosine kinase inhibitors (TKIs), or specific antigens by mAbs. ALL blast cells express a variety of specific antigens (eg, CD19, CD20, CD22, CD33, and CD52) that serve as targets for mAbs. To date, the most data are available for anti-CD20 (rituximab), which has been combined with chemotherapy for the treatment of mature B-ALL/Burkitt lymphoma. Studies with rituximab have also been completed in B-precursor ALL. Another antigen, CD19, is of great interest due to a very high rate of expression in ALL. It can be targeted by a bispecific mAb, blinatumomab, directed against CD19 and CD3. Smaller studies or case reports are also available for the anti-CD52 (alemtuzumab), anti-CD22 (epratuzumab), and anti-CD33 (gemtuzumab) mAbs. Available data demonstrate that mAb therapy in ALL is a highly promising treatment approach. However, several details for an optimal treatment approach, such as the required level of antigen expression, timing, schedule, dosage, and stage of disease, still need to be defined.