Complementary epitopes and favorable developability of monoclonal anti-LAMP1 antibodies generated using two transgenic animal platforms.

Monoclonal antibodies (mAbs) for therapeutic applications should be as similar to native human antibodies as possible to minimize their immunogenicity in patients. Several transgenic animal platforms are available for the generation of fully human mAbs. Attributes such as specificity, efficacy and Chemistry, Manufacturing and Controls (CMC) developability of antibodies against a specific target are typically established for antibodies obtained from one platform only. In this study, monoclonal antibodies (mAbs) cross-reactive against human and cynomolgus LAMP1 were derived from the human immunoglobulin transgenic TRIANNI mouse and OmniChicken® platforms and assessed for their specificity, sequence diversity, ability to bind to and internalize into tumor cells, expected immunogenicity and CMC developability. Our results show that the two platforms were complementary at providing a large diversity of mAbs with respect to epitope coverage and antibody sequence diversity. Furthermore, most antibodies originating from either platform exhibited good manufacturability characteristics.

Intramuscular gene transfer of fibroblast growth factor-1 using improved pCOR plasmid design stimulates collateral formation in a rabbit ischemic hindlimb model.

Fibroblast growth factor 1 (FGF1) is an angiogenic factor known to play a role in the growth of arteries. The purpose of this study was to evaluate the usefulness of direct intramuscular injection of an optimized expression plasmid encoding FGF1 to augment collateral formation and tissue perfusion in a rabbit ischemic hindlimb model. Truncated FGF1 fused to the human fibroblast interferon (FIN) signal peptide was expressed from a newly designed plasmid backbone with an improved safety profile for gene therapy applications. In vitro, optimization of plasmid design yielded in a dramatic increase in expression efficiency for FGF1, independent of the presence of a signal peptide, as analyzed by Western Blotting. In vivo, successful transgene expression could be demonstrated by FGF1 immunostaining after gene application. FGF1 plasmid containing FIN signal peptide (100, 500, and 1,000 mug), when injected into ischemic muscle areas of rabbits 10 days after ligation of the external iliac artery, exhibited a pronounced therapeutic effect on collateral formation to the ischemic hindlimb in a dose-depending manner, as assessed by physiological (blood pressure ratio, maximal intra-arterial Doppler flow) and anatomical (angiographic score, histologic evaluation of capillary density) measurements 30 days after therapy, compared to saline or lacZ control plasmid. FGF1 plasmid without a signal peptide sequence resulted in a comparable therapeutic effect on collateral formation at comparable doses (500 and 1,000 mug). Our results indicate that intramuscular FGF1 gene application could be useful to stimulate collateral formation in a situation of chronic peripheral ischemia. The presence of a signal peptide does not seem to be obligatory to achieve bioactivity of intramuscular transfected FGF1. An optimized vector design improved both biosafety of gene transfer and expression efficiency of the transgene, rendering this vector highly suitable for human gene therapy. Therefore, this new generation vector encoding FGF1 might be useful as an alternative treatment for patients with chronic ischemic disorders not amenable to conventional therapy.