Multipurpose antibody derivatives

Details Multipurpose antibody derivatives Multipurpose antibody derivatives

2000-07-24

2004-10-26

Helms, Larry R. (Department: 1642)

Chemistry: natural resins or derivatives; peptides or proteins;

Proteins, i.e., more than 100 amino acid residues

Blood proteins or globulins, e.g., proteoglycans, platelet...

C530S387100, C530S388100

Reexamination Certificate

active

06809185

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a class of molecules specified as novel multipurpose antibody derivatives. The invention further relates in particular to such antibody derivatives that have two or more antigen binding parts, derivatives that have at least two antigen binding parts, combined with at least one other function, such as a toxin, an enzyme, a cytokine, a hormone or a signalling molecule, and derivatives that have an antigen binding part, combined with at least two other functions.
BACKGROUND OF THE INVENTION
Due to their versatility, multipurpose antibody derivatives (mpAbs), such as bispecific antibodies (BsAb), immunotoxins and bifunctional antibodies are promising tools in the treatment of various (human) diseases. The first arm usually allows to specifically recognize a target cell (e.g. cancer cell) by means of an antigen binding function, while another determinant may be directed through an antigen binding function towards a second cell type (e.g. a cytotoxic T cell), or it may be a toxin, an enzyme (e.g. to locally cleave and activate a prodrug), a cytokine, a hormone or a signalling molecule.
The difficulty of producing functional BsAb in sufficient quantity and purity is still hampering the more general use of BsAb in clinical applications. When using the guadroma technology only 10% of the immunoglobulin pool is the correct, bispecific antibody. Therefore, time consuming and costly purification procedures are inevitable.
Chemical reassociation of antibody fragments suffers from loss of affinity by protein denaturation or unorthodox disulphide bond formation, as well as from the use of a chemical cross-linker, generating inactive, chemically modified structures.
Both these classical methods producing BsAb give rather low yields. Recombinant DNA methodology and antibody engineering has greatly facilitated the production of antibody derivatives in heterologous expression systems. By genetic fusion of various antibody fragments to generate BsAb, the normal tetrameric antibody structure (H+L)
2
is reduced. When the total Fc-portion is included, the self-association of the disulphide bridges in the hinge region reduces considerably the yield of heterodimeric BsAb. Hence purification away from bivalent, homodimeric by-products is still required. In order to improve the level of heterodimeric, bispecific product, a “Knobs-into-holes” principle has been developed to engineer the CH3 domains in the Fc-tail for preferential heterodimerization. The molecule proposed by Ridgway et al. (1996) comprises a complete Fc portion, which increases the molecular weight of the final protein beyond the optimal size for biodistribution. Furthermore, the Fc portion can interact with a multitude of Fc receptors present on various cells in the body, which can deviate the binding of this molecule to aspecific targets.
Small antibody-derivatives (such as sFv, bssFv, (diabodies) have the advantage of easy penetration in solid tumors; moreover, partly because of the absence of high disulphide containing hinge regions, they can be produced in high amounts in heterologous expression systems. However, due to their small size, these molecules are generally cleared too rapidly from the circulation to allow efficient accumulation at the tumor site, while molecules of intermediate size have improved serum stability and retain satisfactory tissue penetration.
In order to achieve medium sized heterodimers, sFv have been linked by incorporating an additional peptide, leucine zippers, amphiphatic helices or streptavidin. These heterodimerization extensions, however, might be immunogenic.
Similar problems are encountered in the preparation of immunotoxins and antibody derivatives having an enzymatic function. Monovalent single chain Fv fragments (sFv) or disulfide stabilized Fv fragments (dsFv) are predominantly used to construct toxin fusions. This results in weaker binding and poor internalization due to the monovalent binding, and rapid blood clearance due to the small molecule size.
DISCLOSURE OF INVENTION
In view of the above it is the object of the present invention to provide a class of molecules, specified as novel multipurpose antibody derivatives that can be efficiently prepared without many by-products, that have an intermediate size and that combine two or more antigenic binding sites, or one antigenic binding site with two or more other functions in one molecule.
This is achieved according to the invention by multipurpose antibody derivative, comprising the CL and VL domains of a first antibody with a desired first antigen binding specificity, the CH1 and VH domains of the said first antibody interacting with the CL and VL domains, and one or more other molecules having at least one further purpose coupled to one or more of the domains of the first antibody.
The invention is based on the potential of the specific VL-CL:VH-CH1 (referred to as “L:Fd”) interaction to drive disulphide-stabilized heterodimerization of recombinant antibody-derived fusion proteins. The use of the L:Fd interaction which can be both natural or chimeric to drive heterodimerization has several advantages. First of all, their natural heterodimeric interaction circumvents the need for protein engineering to achieve complementarity. Furthermore, the interaction is very strong, in contrast to L:L homodiners which are only poorly formed or Fd:Fd homodimers which were never detected in eukaryotic expression systems. Also, in bacterial expression systems the Fd chain alone is aberrantly folded (Ward, 1992). Finally, a single, natural disulphide bridge stabilizes the L:Fd heterodimer.
Each of the two domains of the light and heavy chain can be extended with another molecule (e.g. VL or VH region, a sFv, a toxin, an enzyme such as a prodrug cleaving enzyme, a cytokine, a hormone, a signalling molecule, etc.).
Thus, the invention relates to a class of molecules specified herein as novel “multipurpose antibody derivatives”. This class of molecules is created by heterodimerization of two constituting components. Heterodimerization is obtained by the specific heterotypic interaction of a chosen CH1-VH combination of immunoglobulin domains, with a chosen CL-VL combination of immunoglobulin domains. The VHCH1-VLCL interaction is proposed as a very efficient heterodimerization scaffold that could be efficiently produced. By choosing the tappropriate VH and VL domains in the VHCH1 and VLCL context, a binding specificity can be constituted by the heterodimerization scaffold itself. One or both of the comprising VHCH1 and VLCL chains can thus be extended at either the N- or the C-terminus or both with other molecules, such as a toxin, an enzyme, a cytokine, a hormone or a signalling molecule and derivatives that have an antigen binding part for the purpose of combining these molecules with each other.
The construction of the Fab part of the antibody, fixed to relatively simple molecules such as bacterial alkaline phosphatase, or a truncated mutant form of Pseudomonas exotoxin has been described before (Ducancel et al., 1993, Choe et al., 1994). However, unexpectedly it was found according to the invention that the L:Fd interaction is still able to drive the heterodimerization when one of the chains of the Fab is fused to a complex molecule as a single-chain antibody fragment. Even more unexpectedly, it was found that also both chains of the Fab may be fused to other molecules, without affecting the ability of the molecules to form preferentially heterodimers.
ScFv molecules consist of domains (VL and VH) of the same nature as can be found in the Fd and L chains, so wrongly formed non-functional derivatives could easily be expected. However, the findings as illustrated in the examples unexpectedly show that such molecules can be produced efficiently and is proven functional for all its components.
Surprisingly, this could be achieved with peptide linkers as short as a few amino acids. By excluding the hinge-region, dimerization of the Fab-scFv fusion is omitted. Homodimerization of some specificities might ind

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