Moxetumomab pasudotox

CD22 is a lineage-restricted B-cell antigen that is expressed solely in on B-chronic lymphocytic leukemia, hairy cell leukemia, acute lymphocytic leukemiathe and Burkitt's lymphoma. The predecessor of Moxetumab pasudotox (MxP), named BL22, was first created based on the antibody RFB4 which specifically binds to CD22. This antibody was used to generate a recombinant immunotoxin in which a stabilized Fv segment by a disulfide bond is fused to the Pseudomonas exotoxin A (PE38) which does not have the cell-binding portion.

MxP appears as an improved form of BL22 by the mutation of the Fv region and the antibody phage-displayed. As well the residues SSY in the heavy chain are mutated to THW. It was developed by Astra Zeneca and FDA approved on September 13, 2018, after being granted the status of Fast Track, Priority Review and Orphan Drug designations.

MxP is indicated for the treatment of adult patients with relapsed or refractory hairy cell leukemia (HCL) who received at least two prior systemic therapies including treatment with a purine nucleoside analog. The use of this drug is not recommended in patients with severe renal impairment (CrCl < 29 ml/min).

HCL is an uncommon type of lymphocytic leukemia that starts in B cells or B lymphocytes. It is characterized by an accumulation of abnormal B lymphocytes. HCL is called "hairy" as it produces hair-like projections in the surface of the cancer cells. A usual symptom in people having HCL is the presence of splenomegaly and less often hepatomegaly.