Gene targeting as a therapeutic avenue in diseases mediated by the complement alternative pathway.

The complement alternative pathway (AP) is implicated in numerous diseases affecting many organs, ranging from the rare hematological disease paroxysmal nocturnal hemoglobinuria (PNH), to the common blinding disease age-related macular degeneration (AMD). Critically, the AP amplifies any activating trigger driving a downstream inflammatory response; thus, components of the pathway have become targets for drugs of varying modality. Recent validation from clinical trials using drug modalities such as inhibitory antibodies has paved the path for gene targeting of the AP or downstream effectors. Gene targeting in the complement field currently focuses on supplementation or suppression of complement regulators in AMD and PNH, largely because the eye and liver are highly amenable to drug delivery through local (eye) or systemic (liver) routes. Targeting the liver could facilitate treatment of numerous diseases as this organ generates most of the systemic complement pool. This review explains key concepts of RNA and DNA targeting and discusses assets in clinical development for the treatment of diseases driven by the alternative pathway, including the RNA-targeting therapeutics ALN-CC5, ARO-C3, and IONIS-FB-LRX, and the gene therapies GT005 and HMR59. These therapies are but the spearhead of potential drug candidates that might revolutionize the field in coming years.

Facile immunotargeting of nanoparticles against tumor antigens using site-specific biotinylated antibody fragments.

Nanotechnology is actively being developed for preclinical and clinical oncology applications. Nanoparticle-based immunotargeting against tumor antigens with antibodies or antibody fragments is designed to increase the nanoparticle concentration at the tumor site. However, chemical-based strategies for bioconjugating antibody fragments to nanoparticles typically result in a functionally heterogeneous population of conjugates due to alteration of amino acids within the antigen binding site. The loss of function can be prevented by expressing recombinant antibodies that contain a unique bioconjugation site, which is isolated from the antigen binding site. Biobodies are antibody fragments biosynthetically biotinylated by yeast at a specific biotin acceptor site and secreted into the culture supernatant. The high specificity and affinity between streptavidin-labeled nanoparticles and soluble biobodies allow self-assembly of immunotargeted nanoparticles directly in the yeast culture supernatant. Here, we demonstrate the versatility of biobodies for nanoparticle immunotargeting using streptavidin-labeled superparamagnetic iron oxide nanoparticles as a general, modular scaffold. Biobody-mediated targeting was performed against two antigens (mesothelin and TEM1) that are upregulated in solid tumors. The technology for biosynthetic biotinylation can be extended to proteins other than antibody fragments and adopted by fields outside of oncology for directed modification of any streptavidin-functionalized surface.