Nanobodies and Nanobody-Based Human Heavy Chain Antibodies As Antitumor Therapeutics

Abstract

Monoclonal antibodies have revolutionized cancer therapy. However, delivery to tumor cells in vivo is hampered by the large size (150 kDa) of conventional antibodies. The minimal target recognition module of a conventional antibody is composed of two non-covalently associated variable domains (VH and VL). The proper orientation of these domains is mediated by their hydrophobic interface and is stabilized by their linkage to disulfide-linked constant domains (CH1 and CL). VH and VL domains can be fused via a genetic linker into a single-chain variable fragment (scFv). scFv modules in turn can be fused to one another, e.g., to generate a bispecific T-cell engager, or they can be fused in various orientations to antibody hinge and Fc domains to generate bi- and multispecific antibodies. However, the inherent hydrophobic interaction of VH and VL domains limits the stability and solubility of engineered antibodies, often causing aggregation and/or mispairing of V-domains. Nanobodies (15 kDa) and nanobody-based human heavy chain antibodies (75 kDa) can overcome these limitations. Camelids naturally produce antibodies composed only of heavy chains in which the target recognition module is composed of a single variable domain (VHH or Nb). Advantageous features of nanobodies include their small size, high solubility, high stability, and excellent tissue penetration in vivo. Nanobodies can readily be linked genetically to Fc-domains, other nanobodies, peptide tags, or toxins and can be conjugated chemically at a specific site to drugs, radionuclides, photosensitizers, and nanoparticles. These properties make them particularly suited for specific and efficient targeting of tumors in vivo. Chimeric nanobody-heavy chain antibodies combine advantageous features of nanobodies and human Fc domains in about half the size of a conventional antibody. In this review, we discuss recent developments and perspectives for applications of nanobodies and nanobody-based human heavy chain antibodies as antitumor therapeutics.

Considerations for the Design of Antibody-Based Therapeutics

“…Even smaller than scFvs are single-domain antibodies (sdAbs), which are 15-kDa V L , V H , or V HH domains. 192 The most popular of these are V HH sdAbs, or nanobodies, which are derived from heavychain antibodies that are produced by camelids. These 80-kDa heavy-chain antibodies (so named because they lack light chains) contain a single antigen-binding domain, V HH , directly in the Nterminal of the hinge.…”

Single-domain antibodies as promising experimental tools in imaging and isolation of porcine epidemic diarrhea virus

“…In addition, sdAb is easily selected and cloned by selection systems such as phage, yeast, or ribosomal display (Harmsen and De Haard 2007;Muyldermans et al 2009). These attributes make sdAbs suitable for many medical, biotechnological, diagnostic, and therapeutic applications (Arbabi-Ghahroudi 2017; Bannas et al 2017;Beghein and Gettemans 2017;Gonzalez-Sapienza et al 2017).…”

Light-responsive monobodies for dynamic control of customizable protein binding

“…The high binding affinity and selectivity of antibodies and antibody-like proteins, such as monobodies, nanobodies, affibodies, anticalins and DARPins, have made them central tools of modern medicine, biotechnology, and basic and applied research 1–7 . Because of their ability to be raised, selected, or designed to bind practically any protein of interest 6,8,9 , these protein binders have found multiple applications in diagnostics 3,10,11 , therapeutics 4,12,13 and biologics manufacturing 14–16 . As such, they have revolutionized the way we treat disease 13,17–19 , purify proteins 20–23 , and study biological phenomena 9,24–27 .…”