In Vitro Evaluation of Targeted Antisense Lu-177 Radiotherapy

Background: The BCL2 proto-oncogene in non-Hodgkin's lymphoma is a dominant inhibitor of apoptosis. The goal of this work was to develop a Lu-177-labeled anti-BCL2-peptide nucleic acid (PNA) conjugate designed for dual modality NHL therapy, i.e., simultaneous down-regulation of BCL2-mediated resistance to apoptosis and delivery of cytotoxic internally emitted radiation. Materials and Methods: The effect of 1,4,7,10-tetraazacyclododecane-N,N',N ",N"'-tetra-acetic acid (DOTA)-anti-BCL2-Tyr(3)-octreotate was evaluated by uptake, efflux, proliferation, and viability assays, using Mec-1 lymphoma cells. In vitro dosimetry was modeled with a Monte Carlo projection. Results: Cellular efflux indicated moderate retention of radioactivity in the Mec-1 cells. Viability studies using the Lu-177-labeled PNA conjugate indicated a mass-dose dependence and strongly additive statistical effect in reducing cellular viability. Conclusion: These studies demonstrate the ability of a BCL2 antisense PNA conjugate to specifically target, be retained in, and reduce cellular viability in Mec-1 NHL cells. The results also hold promise for the development of a therapeutic radiopharmaceutical with potential dual modality function.