Blockade of bulky lymphoma‐associated CD55 expression by RNA interference overcomes resistance to complement‐dependent cytotoxicity with rituximab

Abstract

Recently, anti-CD20 (rituximab) and anti-Her2/neu (trastuzumab) antibodies have been developed and applied to the treatment of malignant lymphoma and breast cancer, respectively. However, bulky lymphoma is known to be resistant to rituximab therapy, and this needs to be overcome. Fresh lymphoma cells were collected from 30 patients with non-Hodgkin's lymphoma, the expression of CD20 and CD55 was examined by flow cytometry, and complement-dependent cytotoxicity (CDC) assays were carried out. Susceptibility to CDC with rituximab was decreased in a tumor size-dependent manner (r = -0.895, P < 0.0001), but not in a CD20-dependent manner (r = -0.076, P = 0.6807) using clinical samples. One complement-inhibitory protein, CD55, contributed to bulky lymphoma-related resistance to CDC with rituximab. A decrease in susceptibility to CDC with rituximab was statistically dependent on CD55 expression (r = -0.927, P < 0.0001) and the relationship between tumor size and CD55 expression showed a significant positive correlation (r = 0.921, P < 0.0001) using clinical samples. To overcome the resistance to rituximab by high expression of CD55 in bulky lymphoma masses, small interfering RNA (siRNA) was designed from the DNA sequence corresponding to nucleic acids 1-380 of the CD55 cDNA.

Superior Activity of Fusion Protein scFvRit:sFasL over Cotreatment with Rituximab and Fas Agonists

“…Primary refractory disease or the development of relapses after rituximab treatment has been attributed to several mechanisms, including intrinsic or acquired resistance to complement-dependent cytotoxicity due to overexpression of CD55 and CD59 (22)(23)(24). Because scFvRit:sFasL directly induces apoptosis, which solely requires the cross-linking of CD20 and Fas, scFvRit:sFasL may be particularly relevant for patients with poor or absent complementdependent cytotoxicity.…”

The dual role of complement in cancer and its implication in anti-tumor therapy

“…A decrease in susceptibility to CDC with rituximab was dependent on DAF expression in experiments utilizing an anti-CD55 mAb (96), strengthening the notion that pharmaceutical exploitation of mCRPs can lead to better treatment efficiencies. Moreover, tumor size was positively correlated with DAF expression levels in clinical samples (97,98). In an effort to further explore this mechanism, Zell et al (99) applied anti-sense phosphorothioate oligonucleotides (S-ODNs) to knock down the expression of CD55 in a number of tumor cell lines and found increased C3 opsonization of the cells together with enhanced CDC.…”

Regulation of complement and modulation of its activity in monoclonal antibody therapy of cancer

“…Knock-down of single or multiple mCRPs resulted in a significant increase of CDC in vitro of tumor cell lines of different origin. 80,81 A combination of chemicallystabilized anti-mCRP siRNAs using cationic lipoplexes and treatment with a mixture of anti-Her2 mAbs (trastuzumab and pertuzumab) targeting different epitopes resulted in augmented CDC, complement-mediated cell death and caspase activity and CDCC by macrophages of breast, ovarian, and lung cancer cell lines. 82 A potent CD59 inhibitor (rILYd4) sensitized normally rituximab-resistant lymphoma cells to CDC by rituximab 83 and ofatumumab.…”