Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
1998-06-30
2001-01-09
Chan, Christina Y. (Department: 1644)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C530S387300, C530S388730, C435S320100, C435S252300, C435S069600
Reexamination Certificate
active
06172213
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to immunoglobulin E (IgE), IgE antagonists, anti-IgE antibodies capable of binding to human IgE, and to a method of improving polypeptides, including anti-IgE antibodies.
IgE is a member of the immunoglobulin family that mediates allergic responses such as asthma, food allergies, type 1 hypersensitivity and the familiar sinus inflammation suffered on a widespread basis. IgE is secreted by, and expressed on the surface of B-cells or B-lymphocytes. IgE binds to B-cells (as well as to monocytes, eosinophils and platelets) through its Fc region to a low affinity IgE receptor, known as Fc&egr;RII. Upon exposure of a mammal to an allergen, B-cells bearing a surface-bound IgE antibody specific for the antigen are “activated” and developed into IgE-secreting plasma cells. The resulting allergen-specific IgE then circulates through the bloodstream and becomes bound to the surface of mast cells in tissues and basophils in the blood, through the high affinity receptor also known as Fc&egr;RI. The mast cells and basophils thereby become sensitized for the allergen. Subsequent exposure to the allergen causes a cross linking of the basophilic and mast cellular Fc&egr;RI which results in a release of histamine, leukotrienes and platelet activating factors, eosinophil and neutrophil chemotactic factors and the cytokines IL-
3
, IL-
4
, IL-
5
and GM-CSF which are responsible for clinical hypersensitivity and anaphylaxis.
The pathological condition hypersensitivity is characterized by an excessive immune response to (an) allergen(s) resulting in gross tissue changes if the allergen is present in relatively large amounts or if the humoral and cellular immune state is at a heightened level.
Physiological changes in anaphylactic hypersensitivity can include intense constriction of the bronchioles and bronchi of the lungs, contraction of smooth muscle and dilation of capillaries. Predisposition to this condition, however, appears to result from an interaction between genetic and environmental factors. Common environmental allergens which induce anaphylactic hypersensitivity are found in pollen, foods, house dust mites, animal danders, fungal spores and insect venoms. Atopic allergy is associated with anaphylactic hypersensitivity and includes the disorders, e.g., asthma, allergic rhinitis and conjunctivitis (hay fever), eczema, urticaria and food allergies. However anaphylactic shock, a dangerous life-threatening condition anaphylaxis is usually provoked by insect stings or parental medication.
Recently, a treatment strategy has been pursued for Type 1 hypersensitivity or anaphylactic hypersensitivity which attempts to block IgE from binding to the high-affinity receptor (Fc&egr;RI) found on basophils and mast cells, and thereby prevent the release of histamine and other anaphylactic factors resulting in the pathological condition.
WO 93/04173, published Mar. 4, 1993 describes human IgE/IgG
1
chimeras wherein IgG
1
residues are substituted for the analogous IgE residues. Applicants' copending application U.S. application Ser. No. 08/405,617 describes humanized anti-IgE antibodies wherein a murine antibody directed against human IgE (MaE
11
) was used to provide the CDR regions which were substituted into an IgG
1
immunoglobulin framework (rhuMaE
25
). A technique of humanization is described in Reichmann, L. et al., (1988)
Nature
332: 323 and in Jones, P. T. et al. (1986),
Nature
321: 522.
While humanization of murine antibodies has been established to provide anti-IgE molecules which provide similar affinity to IgE as murine MaE
11
without the immunogenic response elicited by the latter (Shields et al., (1995)
Int. Arch. Allergy Immunol.
107: 308-312), it has still not resulted in the construction of an anti-IgE with affinity for IgE which is decidedly better than MaE
11
or a murine anti-IgE.
Recombinant monoclonal antibodies are subject to degradation reactions that affect all polypeptides or proteins, such as isomerization of aspartic acid and asparagine residues. As shown the reaction scheme, below, aspartate residues (I) in —Asp-Gly— sequences can isomerize to isoaspartate (III) through a cyclic imide intermediate (II). (Geiger & Clarke,
J. Biol. Chem.
262: 785-794 (1987)). The carboxylic acid side chain of the aspartic acid (I) reacts with the amide nitrogen of the adjacent glycine to form a cyclic aspartic acid intermediate (II) which then forms into an -isoaspartic acid-glycine- residue(III). The equilibrium, rate, and pH dependence of this reaction have been studied in model peptides separated by reversed phase high performance liquid chromatography. (Oliyai & Borchardt,
Pharm Res.
10, 95-102 (1993)). The tendency to undergo isomerization is believed to also depend upon the local flexibility of the portion of the molecule containing the —Asp-Gly— sequence (Geiger & Clarke, supra).
An example of a known antibody which undergoes aspartic acid isomerization is the potent anti-IgE antibody known as rhuMabE-
25
(E-
25
). This event may occur spontaneously, but can be induced to occur when E-
25
is incubated at 37° C. for 21 days. The end result is the insertion of an additional methyl group into the polypeptide backbone of the antibody, which can result in conformational changes and reduction in binding affinity. A study of E-
25
with —c-Asp-Gly— and —iso-Asp-Gly— variants at position VL
32
-
33
indicated that while the isomerization event can be minimized by substitution of alanine or glutamic acid for residue VL
32
, the substitution itself results in a three-fold reduction in binding. Cacia et al., supra.
Thus, there exists a great need for the creation of improved polypeptides, including antibodies, which not only don't exhibit the “deactivating” event of aspartyl isomerization, but also display affinity to the target molecule (e.g., antigen) equal to or greater than the unimproved polypeptide's affinity.
SUMMARY
The present invention relates to a method for improving a polypeptide having affinity to a target molecule by a combination of steps, including: (1) the identification of aspartyl residues which are prone to isomerization; (2) the substitution of alternative residues and screening the resulting mutants for affinity against the target molecule. In a preferred embodiment, the method of substituting residues is affinity maturation with phage display (AMPD). In a further preferred embodiment the polypeptide is an antibody and the target molecule is an antigen. In a further preferred embodiment, the antibody is anti-IgE and the target molecule is IgE.
In an even more preferred embodiment, the invention relates to a method for improving the affinity of the anti-IgE antibody E-
25
by replacement of VL CDR-L
1
residue
32
Asp with Glu, along with the modification of VL CDR-L
1
residues
27
Gln,
28
Ser and
31
Tyr to Lys, Pro and Gly, respectively. In an even more preferred embodiment, the E-
25
anti-IgE antibody has additional modifications at residues VH CDR
2
:
53
Thr to Lys,
55
Asp to Ser,
57
Ser to Glu and
59
Asn to Lys.
In another embodiment, the invention relates to an anti-IgE antibody having improved affinity to IgE.
In a preferred embodiment, the anti-IgE antibody comprises heavy and light chain residues comprising the sequence fragments labeled “e
27
” and “e
26
” in FIG.
2
. Alternatively, the anti-IgE antibody comprises the full length heavy and light chain sequences labeled “E
27
” and “E
26
” in FIG.
12
.
The present invention also relates to a composition of improved affinity anti-IgE or functional fragments thereof having pharmaceutical utility. The present invention also relates to an article of manufacture comprising an improved affinity anti-IgE antibody.
In yet another embodiment, the present invention relates to a method of reducing or inhibiting the IgE-mediated production of histamine.
In yet another embodiment, the present invention also relates to a method of treating an IgE-mediated disorder by the administration of the antibodies of the invention or functi
Jardieu Paula M.
Lowe John
Lowman Henry B.
Presta Leonard G.
Chan Christina Y.
Ewoldt Gerald R.
Genentech Inc.
Svoboda Craig G.
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