US 2011/0086049 A1 · Receptor Modulators

Abstract

Method of identifying a modulator of CD28 comprising comparing a structural model of a candidate modulator with a structural model of CD28 to thereby determine whether the modulator will bind to CD28, wherein the structural model is derived from, or comprises, structural coordinates of a crystal of: (i) CD28, (ii) a fragment of CD28, or (iii) a homologue of (i) or (ii). The crystal of CD28 in a soluble form complexed with the Fab fragment of a mitogenic (superagonistic) antibody has been obtained and used for the determination of the 3D-structure of the receptor. The application also relates to modulators of superagonistic signalling for any receptor of the CD28 family, i.e. to superagonistic antibodies and chimeric proteins thereof, and to the screening of the superagonistic modulators. In the methods of screening, the binding of the candidate modulators to a portion of the receptor proximal to the cell membrane is investigated.

A composition of matter comprising:

(a) an isolated antibody that induces superagonistic signaling by a cell surface receptor, wherein said antibody binds to the extracellular portion of the receptor at a membrane proximal region and said receptor comprises a cytoplasmic domain which is dependent on an extrinsic protein kinase, wherein said antibody does not bind only the C′-D loop of human CD28;
(b) an isolated chimeric protein that induces superagonistic signaling by a cell surface receptor, which chimeric protein comprises:
(i) an amino acid sequence comprising a fragment of a ligand of the receptor, or a homologue of such a fragment, wherein the fragment or homologue is capable of binding to the extracellular portion of the receptor at a membrane proximal region, and (ii) an Fc region of an antibody, wherein said receptor comprises a cytoplasmic domain which is dependent on an extrinsic protein kinase;
(c) an isolated chimeric protein that induces superagonistic signaling by one or two types of cell surface receptor, said chimeric protein comprising two Fv regions of an antibody that may be the same or different, wherein at least one of the Fv regions is capable of binding to a first receptor, and the other Fv region either binds to (i) said first receptor, or (ii) a second type of cell surface receptor which is found on a cell that contacts a cell which expresses said first receptor, wherein said first receptor, and optionally also said second receptor, comprises a cytoplasmic domain which is dependent on an extrinsic protein kinase;
(d) an isolated peptide of 5 to 20 amino acids comprising a sequence that binds to an antibody that:
(A) that induces superagonistic signaling by a cell surface receptor, wherein said antibody binds to the extracellular portion of the receptor at a membrane proximal region and said receptor comprises a cytoplasmic domain which is dependent on an extrinsic protein kinase, wherein said antibody does not bind only the C′-D loop of human CD28;
(B) an isolated chimeric protein that induces superagonistic signaling by a cell surface receptor, which chimeric protein comprises:
(i) an amino acid sequence comprising a fragment of a ligand of the receptor, or a homologue of such a fragment, wherein the fragment or homologue is capable of binding to the extracellular portion of the receptor at a membrane proximal region, and (ii) an Fc region of an antibody, wherein said receptor comprises a cytoplasmic domain which is dependent on an extrinsic protein kinase;
or
(C) an isolated chimeric protein that induces superagonistic signaling by one or two types of cell surface receptor, said chimeric protein comprising two Fv regions of an antibody that may be the same or different, wherein at least one of the Fv regions is capable of binding to a first receptor, and the other Fv region either binds to (i) said first receptor, or (ii) a second type of cell surface receptor which is found on a cell that contacts a cell which expresses said first receptor, wherein said first receptor, and optionally also said second receptor, comprises a cytoplasmic domain which is dependent on an extrinsic protein kinase;
(e) a crystal comprising (i) CD28;
(ii) a fragment of CD28;
or (iii) a homologue of CD28 or a fragment thereof;
(f) a crystal comprising a CD28 specific antibody or an antigen binding fragment of said antibody bound to:
(i) CD28;
(ii) a fragment of CD28;
or (iii) a homologue of CD28 or a fragment of thereof;
(g) a crystal having the structural coordinates shown in Table 4;
(h) machine-readable data storage medium comprising a data storage material encoded with a machine readable data which when read by an appropriate machine displays a representation of a crystal:
(A) comprising (i) CD28;
(ii) a fragment of CD28;
or (iii) a homologue of CD28 or a fragment thereof;
(B) comprising a CD28 specific antibody or a fragment of said antibody bound to:(i) CD28;
(ii) a fragment of CD28;
or (iii) a homologue of CD28 or a fragment thereof;
or
(C) having the structural coordinates shown in Table 4;
or
(i) a computer program product comprising a program code means stored on a computer readable storage medium for comparing a structural model of a candidate modulator with a structural model of CD28 to thereby determine whether the modulator will bind to CD28, wherein the structural model is derived from, or comprises, structural coordinates of a crystal of:
(i) CD28, (ii) a fragment of CD28, or (iii) a homologue of CD28 or a fragment of CD28.

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Receptor Modulators

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Receptor Modulators

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Abstract

Claims19