The synergistic interaction between CD20 monoclonal antibodies and Histone Deacetylase inhibitors in B cell Non Hodgkin’s Lymphoma

Recent improvements in molecular sub typing of Non Hodgkin’s lymphomas<br/>have resulted in targeted therapies becoming incorporated into treatment<br/>paradigms. The anti-CD20 monoclonal antibody, Rituximab, has resulted in<br/>dramatic improvements in survival for patients with B cell Non Hodgkin’s<br/>lymphoma. Histone deacetylase inhibitors are a novel class of anti cancer<br/>agents targeting epigenetic regulation.<br/><br/>This thesis addresses the interaction between histone deacetylase inhibitors<br/>and anti-CD20 monoclonal antibodies, including Rituximab, both in vitro and<br/>in vivo. The initial approach identified synergistic induction of apoptosis in a<br/>number of B cell lines. In a Ramos xenograft model, combination treatment<br/>with suberoylanilide hydroxamic acid (SAHA) and Rituximab reduced tumour<br/>growth compared to either agent alone, without discernable toxicity. This<br/>effect appears specific to CD20 since monoclonal antibodies directed to other<br/>surface molecules (CD32b, CD22, CD37) did not exhibit cooperative effect.<br/>Analysis of apoptotic pathways demonstrated that PARP cleavage and<br/>caspase processing is significantly higher in cells receiving both treatments.<br/>Co-treatment of Ramos cells with the pan caspase inhibitor QVD-OPH<br/>abolished the synergy observed with CD20 monoclonal antibodies,<br/>suggesting that caspase processing is necessary for synergy. Treatment of<br/>Ramos cells stably transfected to overexpress Bcl-2 resulted in loss of<br/>synergy with Rituximab, but not with the type II CD20 mAb B1 (Tositumomab).<br/><br/>Gene expression array analysis of Ramos cells was performed. Geneset<br/>enrichment analysis identified significant regulation of NF?B target genes in<br/>some genesets (Rituximab Vs control, p&lt;0.001) with a number associated<br/>with apoptosis and B cell activation (Bcl2A1, LTA, CD69) which were<br/>confirmed using RT-Q-PCR.<br/><br/>This novel combination elicits the induction of apoptosis in vitro, potentially<br/>through regulation of Bcl-2 family proteins and should be tested in a phase<br/>I/II clinical trial.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2010

Author dc:creator

• Nolan, David Francis Luke

Advisor dc:contributor.advisor

• Packham, Graham