Abstract
Purpose: :
Anti-angiogenic molecules have been successfully used in the treatment of wet AMD. However, only about 30% of treated patients gain 3 lines of vision. The presence of 70% afflicted patients suggests a separate mechanism in wet AMD pathology not addressed by standard anti-VEGF therapies. The current study was carried out to explore the concept of a combination therapy - the simultaneous delivery of two biotherapeutics, each with different bioactivities, from one device. An example of a clinically relevant dual-secreting biologic device would be one that produces an anti-angiogenic VEGF antagonist and also the neuroprotective cytokine, CNTF, as dual mode therapy for Wet AMD with underlying photoreceptor lesions.
Methods: :
An iterative transfection strategy was used to create combination VEGF antagonist / CNTF cell lines. VEGF antagonist expression vectors were cloned, then transfected into NTC-200 cells followed by screening for highest productivity. Top producing VEGF antagonist cell lines were subsequently expanded, transfected with CNTF expression vectors and screened for top CNTF producers. Dual producing VEGF antagonist / CNTF cell lines were obtained and subsequently encapsulated to create Neurotech ocular ECT implants. The rate of protein secretion was determined by ELISA.
Results: :
Dual biologic producing clonal cell lines exhibited robust recombinant protein secretion, with levels of some cell lines approaching 15 pcd for VEGF antagonist, and 0.5 pcd for CNTF cytokine. Cell lines were then encapsulated, and production of recombinant proteins from individual ECT devices were detected.
Conclusions: :
Proof-of-concept, dual-secreting cell line studies suggest that Neurotech ECT devices may be an effective method of delivering biologics in a combinatorial approach where such therapies may be preferable, such as a case for Wet / Dry AMD.
Keywords: vascular endothelial growth factor • neuroprotection • retinal pigment epithelium