Furthermore, analysis of known single-nucleotide polymorphisms revealed not only a change in expression of Cd22 but also that its expression became allele specific in tumors.
C61-LNP plus low dose TBI also yielded progression-free survival, tumor-free survival and overall survival outcomes in CD22ΔE12 × BCR-ABL double transgenic mice with advanced stage, radiation-resistant BPL with lymphomatous features that were significantly superior to those of mice treated with TBI alone or C61-LNP alone.
Forced expression of the mutant CD22ΔE12 protein in transgenic mice perturbs B-cell development, as evidenced by B-precursor/B-cell hyperplasia, and corrupts the regulation of gene expression, causing reduced expression levels of several genes with a tumor suppressor function.
These results suggest that in the tumor-bearing state a portion of the mucins in the bloodstream was taken up by the spleen and ligated to CD22 expressed on splenic B cells, which may have led to down-regulation of signal transduction.
The dimeric fusion protein killed several CD22(+) tumor cell lines with high efficacy (IC(50)=3-20 nM) and exhibited 9- to 48-fold stronger cytotoxicity than a monovalent rapLRI-scFv counterpart.
After 4-7 days of growth, these organotypic cultures were treated with media alone, SS1(dsFv)PE38, and a control immunotoxin RFB4(dsFv)PE38, which targets the CD22 antigen not present on gynecologic tumors, every other day x 3.
These data show that VpreB RNA expression is a marker of the malignant forms of precursor B cells, and that it appears at least as early as cytoplasmic CD22 and CD19 in tumors of the B-cell lineage.