WO2020186256A1 - Methods of treating immunoglobulin a nephropathy (igan) using axl decoy receptors - Google Patents

Abstract

Compositions and methods are provided for treating immunoglobulin A nephropathy (IgAN) in a mammal by administering a therapeutic dose of a pharmaceutical composition that inhibits AXL protein activity, for example by inhibition of the binding interaction between AXL and its ligand GAS6.

Description

METHODS OF TREATING IMMUNOGLOBULIN A NEPHROPATHY (IGAN)

USING AXL DECOY RECEPTORS

RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Provisional Application No. 62/818,107, filed on March 14, 2019, incorporated in its entirety by reference herein.

SEQUENCE LISTING

[0002] The instant application contains a Sequence Listing in the form of a“paper copy”

(PDF File) and a file containing the referenced sequences (SEQ D NOS: 1 and 2) in computer readable form (ST25 format text file) which is submitted herein. The Sequence Listing is shown using standard three letter code for amino acids, as defined in 37 C.F.R. 1.822.

TECHNICAL FIELD

[0003] Mesangial proliferation is a common feature of many glomerular diseases, such as diabetic nephropathy, IgA nephropathy (IgAN), Lupus Nephritis and membranoproliferative glomerulonephritis (Striker et al., Lab Invest 64:446^456, 1991 ). IgAN is a nonsystemic renal disease that is characterized by predominant IgA deposition in the glomerular mesangium, causing mesangial proliferation and fibrosis. IgAN is the most common cause of primary glomerulonephritis worldwide and responsible for 10% of patients on dialysis affecting approximately 150,000-180,000 people in the United States. IgAN is caused by IgA deposits in the kidneys, causing mesangial proliferation and fibrosis. Up to 50% of patients with IgAN develop end-stage renal disease and require dialysis within 20 years of diagnosis. Although IgAN is considered an immune complex disease resulting from IgA-immune complex (IgA-IC) glomerular damage, the cause of the disease and the pathogenic mechanisms that propagate this disease are unknown.

[0004] There are no approved drugs for the treatment of IgA nephropathy and only a few therapies are currently in development. Three current development programs target the complement pathway: Omeros Corporation is conducting a phase 3 clinical trial with an injectable MASP-2 inhibitor; Novartis AG is conducting a phase 2 clinical trial with their oral compound, LNP023; and Apellis Pharmaceuticals, Inc. is conducting a phase 2 clinical trial with APL2. Two other programs target B cell activity: EMD Serono Research & Development Institute, Inc. is testing Atacicept in a phase 2 clinical trial and Visterra Inc. is in the midst of testing VIS649in a phase I healthy volunteer clinical trial. There is a high unmet medical need for treatment for IgAN as there are currently no therapies approved drugs for treatment of IgAN.

[0005] Patent documents 13/554,954; 13/595,936; 13/714,875; 13/950, 1 1 1 ;

14/712,731 ; 14/650,852; 14/650,854; 14/910,565; US201 1/022125; US2013/056435;

US2012/069841 ; US2013/074809; US2013/074786; US2013/074796; US2015/0315553 are herein specifically incorporated by reference for all teachings.

DISCLOSURE OF THE INVENTION

[0006] In one aspect, the present invention provides methods for the treatment of immunoglobulin A nephropathy (IgAN), comprising the administration of a soluble AXL polypeptide according to a regimen determined to reduce proteinuria compared to control (baseline prior to treatment). In some embodiments, proteinuria is reduced by at least about 10% to at least about 90% compared to control. In some embodiments, the methods prolong time to requiring dialysis as compared to control.

[0007] In some embodiments, the soluble AXL polypeptide is a soluble AXL variant polypeptide, wherein said soluble AXL variant polypeptide lacks the AXL transmembrane domain, lacks a functional fibronectin (FN) domain, has one or more Ig1 domain, has one or more Ig2 domain, and wherein said AXL variant polypeptide exhibits increased affinity of the AXL variant polypeptide binding to GAS6 compared to wild-type AXL.

[0008] In some embodiments, the soluble AXL polypeptide is a soluble AXL variant polypeptide, wherein said soluble AXL variant polypeptide lacks the AXL transmembrane domain, lacks a functional fibronectin (FN) domain, has one Ig 1 domain, lacks a functional Ig2 domain and wherein said AXL variant polypeptide exhibits increased affinity of the AXL variant polypeptide binding to GAS6 compared to wild-type AXL.

[0009] In some embodiments, the AXL variant polypeptide is a fusion protein comprising an Fc domain. In some embodiments, the variant polypeptide lacks the AXL intracellular domain. In some embodiments, the soluble AXL variant polypeptide further lacks a functional fibronectin (FN) domain and wherein said variant polypeptide exhibits increased affinity of the polypeptide binding to GAS6. In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification relative to the wild-type AXL sequence.

[0010] In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification within a region selected from the group consisting of 1 ) between 15-50, 2) between 60-120, and 3) between 125-135 of the wild-type AXL sequence (SEQ ID NO:1 ).

[0011] In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification at position 19, 23, 26, 27, 32, 33, 38, 44, 61 , 65, 72, 74, 78, 79, 86, 87, 88, 90, 92, 97, 98, 105, 109, 1 12, 1 13, 1 16, 1 18, or 127 of the wild-type AXL sequence (SEQ ID NO: 1 ) or a combination thereof.

[0012] In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification selected from the group consisting of 1 ) A19T, 2) T23M, 3) E26G,

4) E27G or E27K 5) G32S, 6) N33S, 7) T38I, 8) T44A, 9) H61 Y, 10) D65N, 1 1 ) A72V, 12)

S74N, 13) Q78E, 14) V79M, 15) Q86R, 16) D87G, 17) D88N, 18) I90M or I90V, 19) V92A,

V92G or V92D, 20) I97R, 21 ) T98A or T98P, 22) T105M, 23) Q109R, 24) V1 12A, 25) F1 13L,

26) H1 16R, 27) T1 18A, 28) G127R or G127E, and 29) G129E and a combination thereof.

[0013] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) valine 92; and (d) glycine 127.

[0014] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) aspartic acid 87 and (b) valine 92.

[0015] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) valine 92; (d) glycine 127 and (e) alanine 72.

[0016] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following position:

alanine 72.

[0017] In some embodiments, the AXL variant polypeptide glycine 32 residue is replaced with a serine residue, aspartic acid 87 residue is replaced with a glycine residue, valine 92 residue is replaced with an alanine residue, or glycine 127 residue is replaced with an arginine residue or a combination thereof. [0018] In some embodiments, the AXL variant polypeptide residue aspartic acid 87 residue is replaced with a glycine residue or valine 92 residue is replaced with an alanine residue or a combination thereof.

[0019] In some embodiments, the AXL variant polypeptide alanine 72 residue is replaced with a valine residue.

[0020] In some embodiments, the AXL variant polypeptide glycine 32 residue is replaced with a serine residue, aspartic acid 87 residue is replaced with a glycine residue, valine 92 residue is replaced with an alanine residue, glycine 127 residue is replaced with an arginine residue or an alanine 72 residue is replaced with a valine residue or a combination thereof.

[0021] In some embodiments, the AXL variant comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glutamic acid 26; (b) valine 79; (c) valine 92; and (d) glycine 127.

[0022] In some embodiments, the AXL variant polypeptide glutamic acid 26 residue is replaced with a glycine residue, valine 79 residue is replaced with a methionine residue, valine 92 residue is replaced with an alanine residue, or glycine 127 residue is replaced with an arginine residue or a combination thereof.

[0023] In some embodiments, the AXL variant polypeptide comprises at least an amino acid region selected from the group consisting of amino acid region 19-437, 130-437, 19-132,

21 -121 , 26-132, 26-121 and 1 -437 of the wild-type AXL polypeptide (SEQ ID NO: 1 ), and wherein one or more amino acid modifications occur in said amino acid region.

[0024] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; and (d) valine 92.

[0025] In some embodiments, the AXL variant polypeptide glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, and valine 92 is replaced with an alanine residue, or a combination thereof.

[0026] In some embodiments, the soluble AXL polypeptide is a fusion protein further comprising an Fc domain and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; and (d) valine 92.

[0027] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, and valine 92 is replaced with an alanine residue, or a combination thereof.

[0028] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; (d) valine 92; and (e) glycine 127.

[0029] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, valine 92 is replaced with an alanine residue, and glycine 127 is replaced with an arginine residue or a combination thereof.

[0030] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, lacks a functional FN domain, and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; (d) valine 92; and (e) glycine 127.

[0031] In some embodiments, the soluble AXL variant is a fusion protein comprising an

Fc domain, lacks a functional FN domain, and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, valine 92 is replaced with an alanine residue, and glycine 127 is replaced with an arginine residue or a combination thereof.

[0032] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, lacks a functional FN domain, lacks an Ig2 domain, and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72 and (d) valine 92.

[0033] In some embodiments, the soluble AXL variant is a fusion protein comprising an

Fc domain, lacks a functional FN domain, lacks an Ig2 domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, and valine 92 is replaced with an alanine residue or a combination thereof.

[0034] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, lacks a functional FN domain, lacks an Ig2 domain, and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; (d) valine 92; and (e) glycine 127.

[0035] In some embodiments, the soluble AXL variant is a fusion protein comprising an

Fc domain, lacks a functional FN domain, lacks an Ig2 domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, valine 92 is replaced with an alanine residue, and glycine 127 is replaced with an arginine residue or a combination thereof.

[0036] In some embodiments, the soluble AXL variant polypeptide has an affinity of at least about 1 x 10⁸ M, 1 x 10⁹ M, 1 x 10 ¹⁰ M, 1 x 10 ¹¹ M or 1 x 10 ¹² M for GAS6.

[0037] In some embodiments, the soluble AXL variant polypeptide exhibits an affinity to

GAS6 that is at least about 5-fold stronger, at least about 10-fold stronger or at least about 20- fold stronger than the affinity of the wild-type AXL polypeptide.

[0038] In some embodiments, the soluble AXL variant polypeptide further comprises a linker. In some embodiments, the linker comprises one or more (GLY)₄SER units. In some embodiments, the linker comprises 1 , 2, 3 or 5 (GLY)₄SER units. In some embodiments, the linker comprises 1 (GLY)₄SER unit.

[0039] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, a linker, lacks a functional FN domain, and having the amino acid sequence set forth in SEQ ID NO: 2.

[0040] In some embodiments, the dose of the soluble AXL variant polypeptide administered to the patient is selected from the group consisting of about 0.5, of about 1.0, of about 1.5, of about 2.0, of about 2.5, of about 3.0, of about 3.5, of about 4.0, of about 4.5, of about 5.0, of about 5.5, of about 6.0, of about 6.5, of about 7.0, of about 7.5, of about 8.0, of about 8.5, of about 9.0, of about 9.5, of about 10.0 mg/kg, of about 10.5, of about 1 1.0, of about

1 1 .5, of about 12.0, of about 12.5, of about 13.0, of about 13.5, of about 14.0, of about 14.5, of about 15.0, of about 15.5, of about 16.0, of about 16.5, of about 17.0, of about 17.5, of about 18.0, of about 18.5, of about 19.0 mg/kg, of about 19.5, and of about 20.0 mg/kg. In some embodiments, the treatment regimen entails administration once per week. In some

embodiments, the treatment regimen entails administration once per every two weeks. In some embodiments, the treatment regimen entails administration once per every three weeks. In some embodiments, the treatment regimen entails administration once per month or once every 3 to 6 months. [0041] In another aspect, the present invention provides methods for the treatment of

IgAN, comprising the administration of a soluble AXL variant polypeptide that lacks the AXL transmembrane domain and has at least one mutation relative to wild-type AXL that increases affinity of the AXL polypeptide binding to GAS6 compared to wild-type AXL, in combination with a second anti-lgAN therapy. The AXL variant polypeptide may be administered prior to, concurrently with, or following the second therapy.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1. depicts serum GAS6 being elevated in IgAN patients.

MODE(S) FOR CARRYING OUT THE INVENTION

Definitions

[0043] Unless otherwise defined herein, scientific and technical terms used in connection with the present invention shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular. Generally,

nomenclatures used in connection with, and techniques of, cell and tissue culture, molecular biology, immunology, microbiology, genetics and protein and nucleic acid chemistry and hybridization described herein are those commonly used and well known in the art. The methods and techniques of the present invention are generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification unless otherwise indicated. See, e.g., Green and Sambrook, Molecular Cloning: A Laboratory Manual, 4th ed., Cold Spring Flarbor Laboratory Press, Cold Spring Harbor, N.Y. (2012), incorporated herein by reference. Enzymatic reactions and purification techniques are performed according to manufacturer's specifications, as commonly accomplished in the art or as described herein. The nomenclature used in connection with, and the laboratory procedures and techniques of, analytical chemistry, synthetic organic chemistry, and medicinal and pharmaceutical chemistry described herein are those commonly used and well known in the art. Standard techniques are used for chemical syntheses, chemical analyses, pharmaceutical preparation, formulation, and delivery, and treatment of subjects.

[0044] "In combination with", "combination therapy" and "combination products" refer, in certain embodiments, to the concurrent administration to a patient of a first therapeutic and the compounds as used herein. In some embodiments, the combination products are administered non-concurrently. When administered in combination, each component can be administered at the same time or sequentially in any order at different points in time. Thus, each component can be administered separately but sufficiently closely in time so as to provide the desired therapeutic effect.

[0045] The compounds having the desired pharmacological activity may be

administered in a physiologically acceptable carrier to a host to modulate AXL/GAS6 function. The therapeutic agents may be administered in a variety of ways, orally, topically, parenterally e.g. intravenous, subcutaneously, intraperitoneally, by viral infection, intravascularly, etc.

Intravenous delivery is of particular interest. Depending upon the manner of introduction, the compounds may be formulated in a variety of ways. The concentration of therapeutically active compound in the formulation may vary from about 0.1 -100 wt.%.

[0046] The pharmaceutical compositions can be prepared in various forms, such as granules, tablets, pills, suppositories, capsules, suspensions, salves, lotions and the like.

Pharmaceutical grade organic or inorganic carriers and/or diluents suitable for oral and topical use can be used to make up compositions containing the therapeutically-active compounds. Diluents known to the art include aqueous media, vegetable and animal oils and fats.

Stabilizing agents, wetting and emulsifying agents, salts for varying the osmotic pressure or buffers for securing an adequate pH value, and skin penetration enhancers can be used as auxiliary agents.

[0047] "Inhibitors," "activators," and "modulators" of AXL or its ligand GAS6 are used to refer to inhibitory, activating, or modulating molecules, respectively, identified using in vitro and in vivo assays for receptor or ligand binding or signaling, e.g., ligands, receptors, agonists, antagonists, and their homologs and mimetics.

[0048] The terms "polypeptide," "peptide" and "protein" are used interchangeably herein to refer to a polymer of two or more amino acid residues. The terms apply to amino acid polymers in which one or more amino acid residue is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymers. The terms“antibody” and “antibodies” are used interchangeably herein and refer to a polypeptide capable of interacting with and/or binding to another molecule, often referred to as an antigen. Antibodies can include, for example“antigen-binding polypeptides” or“target-molecule binding polypeptides.” Antigens of the present invention can include for example any polypeptides described in the present invention.

[0049] The term "amino acid" refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those amino acids that are later modified, e.g., hydroxyproline, gamma- carboxyglutamate, and O-phosphoserine. Amino acid analogs refer to compounds that have the same basic chemical structure as a naturally occurring amino acid, i.e., an a-carbon that is bound to a hydrogen, a carboxyl group, an amino group, and an R group, e.g., homoserine, norleucine, methionine sulfoxide, methionine methyl sulfonium. Such analogs have modified R groups {e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as a naturally occurring amino acid. Amino acid mimetics refers to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that functions in a manner similar to a naturally occurring amino acid. All single letters used in the present invention to represent amino acids are used according to recognized amino acid symbols routinely used in the field, e.g., A means Alanine, C means Cysteine, etc.

An amino acid is represented by a single letter before and after the relevant position to reflect the change from original amino acid (before the position) to changed amino acid (after position). For example, A19T means that amino acid alanine at position 19 is changed to threonine.

[0050] The terms“subject,”“individual,” and“patient” are used interchangeably herein to refer to a mammal being assessed for treatment and/or being treated. In an embodiment, the mammal is a human. The terms“subject,”“individual,” and“patient” thus encompass individuals having IgAN. Subjects may be human, but also include other mammals, particularly those mammals useful as laboratory models for human disease, e.g. mouse, rat, etc.

[0051] The term“diagnosis” is used herein to refer to the identification of a molecular or pathological state, disease or condition, such as the identification of a virus infection.

[0052] As used herein, the terms“treatment,”“treating,” and the like, refer to

administering an agent, or carrying out a procedure for the purposes of obtaining an effect. The effect may be prophylactic in terms of completely or partially preventing a disease or symptom thereof and/or may be therapeutic in terms of effecting a partial or complete cure for a disease, and/or symptoms of the disease. “Treatment,” as used herein, covers any treatment of any virus infection or exposure in a mammal, particularly in a human, and includes: (a) preventing the infection; (b) inhibiting the infection, i.e., arresting its development; and (c) relieving the disease, i.e., causing regression of infection.

[0053] Treating may refer to any indicia of success in the treatment or amelioration or prevention of IgAN, including any objective or subjective parameter such as abatement;

remission; diminishing of symptoms or making the disease condition more tolerable to the patient; slowing in the rate of degeneration or decline; or making the final point of degeneration less debilitating. The treatment or amelioration of symptoms can be based on objective or subjective parameters; including the results of an examination by a physician. Accordingly, the term "treating" includes the administration of the compounds or agents of the present invention to prevent or delay, to alleviate, or to arrest or inhibit development of the symptoms or conditions. The term "therapeutic effect" refers to the reduction, elimination, or prevention of the disease, symptoms of the disease, or side effects of the disease in the subject.

[0054] As used herein, the term“correlates,” or“correlates with,” and like terms, refers to a statistical association between instances of two events, where events include numbers, data sets, and the like. For example, when the events involve numbers, a positive correlation (also referred to herein as a“direct correlation”) means that as one increases, the other increases as well. A negative correlation (also referred to herein as an“inverse correlation”) means that as one increases, the other decreases.

[0055] "Dosage unit" refers to physically discrete units suited as unitary dosages for the particular individual to be treated. Each unit can contain a predetermined quantity of active compound(s) calculated to produce the desired therapeutic effect(s) in association with the required pharmaceutical carrier. The specification for the dosage unit forms can be dictated by (a) the unique characteristics of the active compound(s) and the particular therapeutic effect(s) to be achieved, and (b) the limitations inherent in the art of compounding such active compound(s).

[0056] "Pharmaceutically acceptable excipient "means an excipient that is useful in preparing a pharmaceutical composition that is generally safe, non-toxic, and desirable, and includes excipients that are acceptable for veterinary use as well as for human pharmaceutical use. Such excipients can be solid, liquid, semisolid, or, in the case of an aerosol composition, gaseous. [0057] The terms "pharmaceutically acceptable", "physiologically tolerable" and grammatical variations thereof, as they refer to compositions, carriers, diluents and reagents, are used interchangeably and represent that the materials are capable of administration to or upon a human without the production of undesirable physiological effects to a degree that would prohibit administration of the composition.

[0058] A "therapeutically effective amount" refers to the amount of a compound that, when administered to a subject for treating IgAN, is sufficient to affect such treatment of IgAN. The "therapeutically effective amount" may vary depending, for example, on the soluble AXL variant polypeptide selected, the stage of the IgAN, the age, weight and/or health of the patient and the judgment of the prescribing physician. An appropriate amount in any given instance may be readily ascertained by those skilled in the art or capable of determination by routine experimentation.

[0059] The phrase“determining the treatment efficacy” and variants thereof can include any methods for determining that a treatment is providing a benefit to a subject. The term “treatment efficacy” and variants thereof are generally indicated by alleviation of one or more signs or symptoms associated with the disease and can be readily determined by one skilled in the art. “Treatment efficacy” may also refer to the prevention or amelioration of signs and symptoms of toxicities typically associated with standard or non-standard treatments of a disease. Determination of treatment efficacy is usually indication and disease specific and can include any methods known or available in the art for determining that a treatment is providing a beneficial effect to a patient. For example, evidence of treatment efficacy can include but is not limited to remission of the disease or indication. Further, treatment efficacy can also include general improvements in the overall health of the subject, such as but not limited to

enhancement of patient life quality, increase in predicted subject survival rate, decrease in depression or decrease in rate of recurrence of the indication (increase in remission time).

(See, e.g., Physicians' Desk Reference (2010).).

[0060] "Concomitant administration" of a known IgAN therapeutic drug with a pharmaceutical composition of the present invention means administration of the drug and AXL variant at such time that both the known drug and the composition of the present invention will have a therapeutic effect. Such concomitant administration may involve concurrent (i.e. at the same time), prior, or subsequent administration of the drug with respect to the administration of a compound of the present invention. A person of ordinary skill in the art would have no difficulty determining the appropriate timing, sequence and dosages of administration for particular drugs and compositions of the present invention.

Glomerular diseases

[0061] Within the kidney, AXL and GAS6 are expressed in vascular smooth muscle cells

(VSMCs), glomerular mesangial cells and tubular cells (Hyde, G.D., et al., PLoS ONE 9, e102096, 2014). The basal expression of GAS6/AXL is low in normal kidney. However, its expression can be upregulated in several murine models of chronic kidney disease (CKD) including: glomerulonephritis (GN) induced by Thy1 .1 antibody, and nephrotoxic nephritis (NS). Patients with CKD have elevated plasma GAS6 levels (Lee, I.J. et al., Nephrol. Dial. Transplant, 27, 4166—4172, 2012).

[0062] It has been demonstrated that GAS6 stimulates mesangial cell proliferation through binding to its cell-surface receptor AXL in vitro (Yanagita et al., J Am Soc Nephrol 10: 2503-2509, 1999). In the same studies, warfarin and the extracellular domain of AXL conjugated with Fc portion of human lgG1 (AXL-Fc) inhibited mesangial cell proliferation by interfering with the GAS6/AXL pathway in vitro. Preclinical data demonstrated that a lower affinity GAS6-trap improves fibrosis and proteinurea in experimental glomerulonephritis and indicated that the GAS6/AXL pathway plays a key role in mesangial cell proliferation in vivo and inhibition of the pathway improves proteinuria (Yanagita et al., Am J Pathol., 158(4):1423-1432, 2001 ). PDGF-B is a key growth factor in driving renal fibrosis, independent of the underlying kidney disease. Yanigati et al also demonstrated that inhibition of the GAS6/AXL pathway reduced the expression of PDGF-B in Thy1 GN. Expression of PDGF-B mRNA was induced in Thy1 GN, whereas the induction was abolished when treated with AXL-Fc. Expression of PDGF-B protein in glomeruli was also abolished in Thy1 GN treated with AXL-Fc. The Yanagita et al. findings indicate that the GAS6/AXL pathway plays a key role in mesangial cell proliferation in vivo and inhibition of the pathway improves proteinuria. Thus, targeting GAS6 may have multiple effects on kidney fibrosis.

[0063] Lupus nephritis often causes end-stage kidney failure due to glomerular and tubular inflammation that is associated with massive cellular proliferation, including mesangial cell proliferation. Studies evaluating the efficacy and mechanism of action of R428, a small kinase inhibitor with selectivity for AXL, in the prevention of experimental preclinical anti- glomerular basement membrane (GBM) nephritis model demonstrated that R428 treatment inhibited AXL and significantly decreased Akt phosphorylation and renal inflammatory cytokine and chemokine expression suggesting targeting the GAS6/AXL pathway could be an effective treatment for anti-GBM induced Lupus-like nephritis (Zhen et al. Journal of Autoimmunity, 93:37 44, 2018).

[0064] Nephrotoxic nephritis (NTN) is a progressive form of GN in which inflammatory cell infiltration and proliferation of intrinsic glomerular cells contribute to glomerular

hypercellularity, the formation of crescentic lesions in the urinary space, and glomerular sclerosis. It has been demonstrated that GAS6 is induced in a preclinical NTN model and that GAS6-/- mice were protected from glomerular injury by NTS. GAS6-/- mice with NTN showed less mortality, less albuminuria, less glomerular injury, less proliferative response, and less deposition of fibrin/fibrinogen in glomeruli than wild-type mice did. Moreover, by the

administration of rGAS6, they were able to induce severe glomerular injury in GAS6-/- mice, indicating the essential role of GAS6 in this GN model (Yanagita et al., J. Clin. Invest. 1 10:239- 246, 2002).

[0065] Nephrologists use clinical information such as extent of proteinuria, presence of hypertension, and excretory renal function to predict the risk of progression of renal disease in IgAN. Protein p27, expressed mainly in podocytes in rat and human normal glomeruli, is a protein associated with progression of IgAN. Expression levels of p27 are decreased in association with mesangial proliferation in experimental mesangial proliferative

glomerulonephritis (rat anti-Thy-1 nephritis model) and human IgAN. Decreased proteinuria is associated with improved survival in IgAN (Coppo et al., Kidney Inti, 86:828-36, 2014; Reich et al., J Am Soc Nephrol, 3177-83, 2007) and proteinuria is the best predictor of renal risk.

[0066] GAS6 is upregulated in either endothelial/mesangial cells or podocytes in IgAN and expression in the diseased kidney tissue correlates with severity of IgAN (Nagai K, et al., PLoS ONE 8(6): e66759, 2013). Nagai, K, et al. reported that in 28 of 31 cases of IgAN, GAS6 was upregulated mainly in podocytes. In the other 3 cases, GAS6 expression was induced in endothelial and mesangial cells. Among 28 podocyte type cases, the expression level of GAS6 correlated with the mesangial hypercellularity score of IgAN Oxford classification and urine protein excretion. GAS6 also inversely correlated with p27 expression. soluble AXL variant polypeptides [0067] The present inventors have previously described a family of novel, high-affinity, soluble Fc-fusion proteins designed to block the activation of the GAS6-AXL signaling pathway by intercepting GAS6 and interfering with its binding to its receptor AXL. These fusion proteins have been engineered to have approximately 50 to 200 times greater affinity for human GAS6 compared to the native AXL receptor, effectively sequestering GAS6 and abrogating AXL signaling (see, e.g., US Patent No. 9,822,347).

[0068] In some embodiments, the soluble AXL polypeptide is a soluble AXL variant polypeptide, wherein said soluble AXL variant polypeptide lacks the AXL transmembrane domain, lacks a functional fibronectin (FN) domain, has one or more Ig1 domain, has one or more Ig2 domain, and wherein said AXL variant polypeptide exhibits increased affinity of the AXL variant polypeptide binding to GAS6 compared to wild-type AXL.

[0069] In some embodiments, the soluble AXL polypeptide is a soluble AXL variant polypeptide, wherein said soluble AXL variant polypeptide lacks the AXL transmembrane domain, lacks a functional fibronectin (FN) domain, has one Ig 1 domain, lacks a functional Ig2 domain and wherein said AXL variant polypeptide exhibits increased affinity of the AXL variant polypeptide binding to GAS6 compared to wild-type AXL.

[0070] In some embodiments, the AXL variant polypeptide is a fusion protein comprising an Fc domain. In some embodiments, the variant polypeptide lacks the AXL intracellular domain. In some embodiments, the soluble AXL variant polypeptide further lacks a functional fibronectin (FN) domain and wherein said variant polypeptide exhibits increased affinity of the polypeptide binding to GAS6. In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification relative to the wild-type AXL sequence.

[0071] In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification within a region selected from the group consisting of 1 ) between 15-50, 2) between 60-120, and 3) between 125-135 of the wild-type AXL sequence (SEQ ID NO:1 ).

[0072] In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification at position 19, 23, 26, 27, 32, 33, 38, 44, 61 , 65, 72, 74, 78, 79, 86, 87, 88, 90, 92, 97, 98, 105, 109, 1 12, 1 13, 1 16, 1 18, or 127 of the wild-type AXL sequence (SEQ ID NO: 1 ) or a combination thereof.

[0073] In some embodiments, the soluble AXL variant polypeptide comprises at least one amino acid modification selected from the group consisting of 1 ) A19T, 2) T23M, 3) E26G, 4) E27G or E27K 5) G32S, 6) N33S, 7) T38I, 8) T44A, 9) H61 Y, 10) D65N, 1 1 ) A72V, 12) S74N, 13) Q78E, 14) V79M, 15) Q86R, 16) D87G, 17) D88N, 18) I90M or I90V, 19) V92A,

V92G or V92D, 20) I97R, 21 ) T98A or T98P, 22) T105M, 23) Q109R, 24) V1 12A, 25) F1 13L,

26) H1 16R, 27) T1 18A, 28) G127R or G127E, and 29) G129E and a combination thereof.

[0074] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) valine 92; and (d) glycine 127.

[0075] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) aspartic acid 87 and (b) valine 92.

[0076] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) valine 92; (d) glycine 127 and (e) alanine 72.

[0077] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following position:

alanine 72.

[0078] In some embodiments, the AXL variant polypeptide glycine 32 residue is replaced with a serine residue, aspartic acid 87 residue is replaced with a glycine residue, valine 92 residue is replaced with an alanine residue, or glycine 127 residue is replaced with an arginine residue or a combination thereof.

[0079] In some embodiments, the AXL variant polypeptide residue aspartic acid 87 residue is replaced with a glycine residue or valine 92 residue is replaced with an alanine residue or a combination thereof.

[0080] In some embodiments, the AXL variant polypeptide alanine 72 residue is replaced with a valine residue.

[0081] In some embodiments, the AXL variant polypeptide glycine 32 residue is replaced with a serine residue, aspartic acid 87 residue is replaced with a glycine residue, valine 92 residue is replaced with an alanine residue, glycine 127 residue is replaced with an arginine residue or an alanine 72 residue is replaced with a valine residue or a combination thereof.

[0082] In some embodiments, the AXL variant comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glutamic acid 26; (b) valine 79; (c) valine 92; and (d) glycine 127.

[0083] In some embodiments, the AXL variant polypeptide glutamic acid 26 residue is replaced with a glycine residue, valine 79 residue is replaced with a methionine residue, valine 92 residue is replaced with an alanine residue, or glycine 127 residue is replaced with an arginine residue or a combination thereof.

[0084] In some embodiments, the AXL variant polypeptide comprises at least an amino acid region selected from the group consisting of amino acid region 19-437, 130-437, 19-132,

21 -121 , 26-132, 26-121 and 1 -437 of the wild-type AXL polypeptide (SEQ ID NO: 1 ), and wherein one or more amino acid modifications occur in said amino acid region.

[0085] In some embodiments, the AXL variant polypeptide comprises amino acid changes relative to the wild-type AXL sequence (SEQ ID NO: 1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; and (d) valine 92.

[0086] In some embodiments, the AXL variant polypeptide glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, and valine 92 is replaced with an alanine residue, or a combination thereof.

[0087] In some embodiments, the soluble AXL polypeptide is a fusion protein further comprising an Fc domain and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; and (d) valine 92.

[0088] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, and valine 92 is replaced with an alanine residue, or a combination thereof.

[0089] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; (d) valine 92; and (e) glycine 127.

[0090] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, valine 92 is replaced with an alanine residue, and glycine 127 is replaced with an arginine residue or a combination thereof.

[0091] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, lacks a functional FN domain, and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; (d) valine 92; and (e) glycine 127.

[0092] In some embodiments, the soluble AXL variant is a fusion protein comprising an

Fc domain, lacks a functional FN domain, and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, valine 92 is replaced with an alanine residue, and glycine 127 is replaced with an arginine residue or a combination thereof.

[0093] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, lacks a functional FN domain, lacks an Ig2 domain, and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72 and (d) valine 92.

[0094] In some embodiments, the soluble AXL variant is a fusion protein comprising an

Fc domain, lacks a functional FN domain, lacks an Ig2 domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, and valine 92 is replaced with an alanine residue or a combination thereof.

[0095] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, lacks a functional FN domain, lacks an Ig2 domain, and wherein said AXL variant comprises amino acid changes relative to wild-type AXL sequence (SEQ ID NO:1 ) at the following positions: (a) glycine 32; (b) aspartic acid 87; (c) alanine 72; (d) valine 92; and (e) glycine 127.

[0096] In some embodiments, the soluble AXL variant is a fusion protein comprising an

Fc domain, lacks a functional FN domain, lacks an Ig2 domain and wherein glycine 32 is replaced with a serine residue, aspartic acid 87 is replaced with a glycine residue, alanine 72 is replaced with a valine residue, valine 92 is replaced with an alanine residue, and glycine 127 is replaced with an arginine residue or a combination thereof.

[0097] In some embodiments, the soluble AXL variant polypeptide has an affinity of at least about 1 x 10⁸ M, 1 x 10⁹ M, 1 x 10 ¹⁰ M, 1 x 10 ¹¹ M or 1 x 10 ¹² M for GAS6.

[0098] In some embodiments, the soluble AXL variant polypeptide exhibits an affinity to

GAS6 that is at least about 5-fold stronger, at least about 10-fold stronger or at least about 20- fold stronger than the affinity of the wild-type AXL polypeptide.

[0099] In some embodiments, the soluble AXL variant polypeptide further comprises a linker. In some embodiments, the linker comprises one or more (GLY)₄SER units. In some embodiments, the linker comprises 1 , 2, 3 or 5 (GLY)₄SER units. In some embodiments, the linker comprises 1 (GLY)₄SER unit.

[00100] In some embodiments, the soluble AXL polypeptide is a fusion protein comprising an Fc domain, a linker, lacks a functional FN domain, and having the amino acid sequence set forth in SEQ ID NO: 2 (AVB-S6-500). AVB-S6-500 is an AXL decoy protein that binds GAS6 with higher affinity than the endogenous AXL protein and inhibits GAS6/AXL signaling. The high affinity soluble receptor offers a novel alternative approach from small molecule drug discovery efforts that directly target AXL. Five amino acid substitutions within this high affinity AXL variant caused structural alterations in side chains across the GAS6/AXL binding interface, stabilizing a conformational change on GAS6. The engineered decoy receptor binds to GAS6 with femtomolar (fM) affinity, representing approximately a 200-fold improvement compared to the wild-type (WT) AXL receptor. The high affinity AXL decoy protein is fused with the Fc region of human IgGl to increase half-life. The AXL decoy proteins effectively sequester GAS6 and abrogate AXL signaling.

[00101] The present inventors have previously demonstrated that AVB-S6-500 effectively abrogates serum GAS6 (sGAS6) levels in tumor bearing mice as well as humans. The elimination of sGAS6 correlated to anti-tumor effects preclinically. Thus, sGAS6 levels provide a useful pharmacodynamic (PD) marker to guide dosing in clinical studies and the dose that abrogated sGAS6 levels in healthy volunteers over a 2-week period (10mg/kg) is being investigated in a Phase 1 b platinum-resistant ovarian cancer study. More specifically, the present inventors are currently testing AVB-S6-500 in clinical studies in the USA. The initial IND (#135920) was filed to investigate AVB-S6-500 as a treatment of several tumor types, including pancreatic, breast, and ovarian cancers. GLP toxicology studies demonstrated a benign safety profile so the initial human study was conducted in healthy volunteers to assess safety, pharmacokinetics and pharmacodynamics (PROTOCOL: AVB500-HV-001 ). All doses tested (from 1 to 10mg/kg single doses and 5mg/kg dose given weekly for 4 weeks) were well- tolerated and suppressed serum GAS6 levels for at least one week. These doses all represented a safety margin relative to the NOAEL in the GLP studies.

[00102] In one aspect, the methods of the present invention include treating or preventing IgAN by administering a soluble AXL variant polypeptide as described herein using a regimen designed to decrease proteinuria as compared to control (baseline prior to treatment). In some embodiments, proteinuria is reduced by at least about 10% to at least about 90% compared to control. In some embodiments, proteinuria is reduced by at least 10% compared to control. In some embodiments, proteinuria is reduced by at least 20% compared to control. In some embodiments, proteinuria is reduced by at least 30% compared to control. In some

embodiments, proteinuria is reduced by at least 40% compared to control. In some

embodiments, proteinuria is reduced by at least 50% compared to control.

[00103] In some embodiments, the methods prolong time to requiring dialysis as compared to control. In some embodiments, the methods prolong overall survival as compared to control. In some embodiments, the methods achieve improved progression free survival as compared to control. In some embodiments, the methods achieve improved time to second subsequent therapy as compared to control.

[00104] In some embodiments, therapeutic entities of the present invention are often administered as pharmaceutical compositions comprising an active therapeutic agent, i.e., and a variety of other pharmaceutically acceptable components. (See Remington's Pharmaceutical Science, 15.sup.th ed., Mack Publishing Company, Easton, Pa., 1980). The preferred form depends on the intended mode of administration and therapeutic application. The compositions can also include, depending on the formulation desired, pharmaceutically acceptable, non-toxic carriers or diluents, which are defined as vehicles commonly used to formulate pharmaceutical compositions for animal or human administration. The diluent is selected so as not to affect the biological activity of the combination. Examples of such diluents are distilled water, physiological phosphate-buffered saline, Ringer's solutions, dextrose solution, and Hank's solution. In addition, the pharmaceutical composition or formulation may also include other carriers, adjuvants, or nontoxic, nontherapeutic, nonimmunogenic stabilizers and the like.

[00105] A useful range for i.v. administered polypeptides may be empirically determined, for example at least about 0.1 mg/kg body weight; at least about 0.5 mg/kg body weight; at least about 1 mg/kg body weight; at least about 2.5 mg/kg body weight; at least about 5 mg/kg body weight; at least about 10 mg/kg body weight; at least about 20 mg/kg body weight; or more. In some embodiments, the dosage of the soluble AXL variant polypeptide administered to the patient is selected from the group consisting of about 0.5, of about 1 .0, of about 1.5, of about 2.0, of about 2.5, of about 3.0, of about 3.5, of about 4.0, of about 4.5, of about 5.0, of about 5.5, of about 6.0, of about 6.5, of about 7.0, of about 7.5, of about 8.0, of about 8.5, of about 9.0, of about 9.5, of about 10.0 mg/kg, of about 10.5, of about 1 1.0, of about 1 1.5, of about 12.0, of about 12.5, of about 13.0, of about 13.5, of about 14.0, of about 14.5, of about 15.0, of about 15.5, of about 16.0, of about 16.5, of about 17.0, of about 17.5, of about 18.0, of about 18.5, of about 19.0 mg/kg, of about 19.5, and of about 20.0 mg/kg. [00106] In some embodiments, the treatment regimen entails administration once per week. In some embodiments, the treatment regimen entails administration once per every two weeks. In some embodiments, the treatment regimen entails administration once per every three weeks. In some embodiments, the treatment regimen entails administration once per month or once every 3 to 6 months.

[00107] In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 20 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 15 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 12.5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 10 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 7.5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 2.5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a weekly dose of 1 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 20 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 15 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 12.5 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 10 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 7.5 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 5 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of

2.5 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 1 mg/kg every 14 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 20 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 15 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 12.5 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 10 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 7.5 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 5 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 2.5 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a dose of 1 mg/kg every 21 days. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 20 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 15 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 12.5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 10 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 7.5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 2.5 mg/kg. In some embodiments, the soluble AXL variant polypeptide will be given as IV infusion over 30 or 60 minutes at a monthly dose of 1 mg/kg.

[00108] In prophylactic applications, a therapeutically effective dosage is administered at relatively infrequent intervals over a long period of time. Some patients continue to receive treatment for the rest of their lives. In therapeutic applications, a relatively high dosage at relatively short intervals is sometimes required until progression of the disease is reduced or terminated, and preferably until the patient shows partial or complete amelioration of symptoms of disease. Thereafter, the patent can be administered a prophylactic regimen.

[00109] Typically, compositions are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid vehicles prior to injection can also be prepared. The preparation also can be emulsified or encapsulated in liposomes or micro particles such as polylactide, polyglycolide, or copolymer for enhanced adjuvant effect, as discussed above. Langer, Science 249: 1527, 1990 and Hanes, Advanced Drug Delivery Reviews 28: 97-1 19, 1997. The agents of this invention can be administered in the form of a depot injection or implant preparation which can be formulated in such a manner as to permit a sustained or pulsatile release of the active ingredient. Additional formulations suitable for other modes of administration include oral, intranasal, and pulmonary formulations, suppositories, and transdermal applications.

[00110] The pharmaceutical compositions are generally formulated as sterile,

substantially isotonic and in full compliance with all Good Manufacturing Practice (GMP) regulations of the U.S. Food and Drug Administration. Preferably, a therapeutically effective dose of the polypeptide compositions described herein will provide therapeutic benefit without causing substantial toxicity.

[00111] T oxicity of the proteins described herein can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., by determining the LD_5O (the dose lethal to 50% of the population) or the LDi₀o (the dose lethal to 100% of the population). The dose ratio between toxic and therapeutic effect is the therapeutic index. The data obtained from these cell culture assays and animal studies can be used in formulating a dosage range that is not toxic for use in human. The dosage of the proteins described herein lies preferably within a range of circulating concentrations that include the effective dose with little or no toxicity. The dosage can vary within this range depending upon the dosage form employed and the route of administration utilized. The exact formulation, route of administration and dosage can be chosen by the individual physician in view of the patient's condition. (See, e.g., Fingl et al., 1975, In: The Pharmacological Basis of Therapeutics, Ch. 1 ).

[00112] In another aspect, the present invention provides methods for the treatment of IgAN, comprising the administration of a soluble AXL variant polypeptide that lacks the AXL transmembrane domain and has at least one mutation relative to wild-type AXL that increases affinity of the AXL polypeptide binding to GAS6 compared to wild-type AXL, in combination with a second anti-lgAN therapy. The AXL variant polypeptide may be administered prior to, concurrently with, or following the second therapy.

[00113] Also within the scope of the invention are kits comprising the compositions of the invention and instructions for use. The compositions may be provided in a unit dose formulation. Kits typically include a label indicating the intended use of the contents of the kit. The term label includes any writing, or recorded material supplied on or with the kit, or which otherwise accompanies the kit. Exemplary Embodiments

Example 1

Evaluation of GAS6 levels in IgAN

[00114] In an effort to understand if serum GAS6 levels are elevated in IgAN patients, the present inventors obtained 20 serum samples from biopsy-confirmed IgAN patients and 20 serum samples from age-matched controls (BioVT, USA). sGAS6 was analyzed per a GLP validated ELISA. We determined that those levels were significantly higher than their age- matched controls. Average sGAS6 levels for IgAN patients was 22ng/mL vs 13ng/mL for age- matched controls (FIG. 1 ).

Example 2

An Open-Label Phase 2 Study to Evaluate the Safety and Pharmacology of a soluble AXL variant-Fc Fusion polypeptide in Subjects with Mesangial Proliferative IgA Nephropathy (IgAN)

[00115] The present inventors are conducting a small open label clinical trial of 12-24 patients with IgAN treated for 12 weeks with 6 doses of a soluble AXL variant-Fc Fusion polypeptide as set forth in SEQ ID NO: 2 (hereinafter“AVB-S6-500”). Treatment duration will be 12 weeks (6 doses of study drug) with 4 weeks of post-treatment follow-up. The primary objective of the clinical trial is to evaluate the safety and tolerability of AVB-S6-500 IV in IgAN patients. Secondary objectives are to characterize the pharmacokinetics and

pharmacodynamics of IV AVB-S6-500 to ensure GAS6 levels are suppressed over the dosing interval. The clinical trial will monitor proteinuria, hematuria and other renal functions and biopsies of patients will be taken before and after treatment to assess the effect on renal tissue and AXL activity.

[00116] All subjects will have biopsy proven mesangial proliferative IgAN, persistent proteinuria ³ 1 g/24hr but < 3g/24hr, presence of microhematuria, be on a steady dose of ACE or ARB inhibitors, will not have received oral or parenteral corticosteroids or immunosuppressants within 6 months of screening. Efficacy, pharmacodynamic, and pharmacokinetic assessments will be performed during the 12 weeks of treatment. Safety will be assessed throughout the 16 weeks of study.

[00117] AVB-S6-500 will initially be administered at a dose of 10mg/kg by intravenous infusion over 30 minutes. AVB-S6-500 solution for infusion will be packaged and labeled according to current Good Manufacturing Practices and supplied to the clinical sites in 20 ml_- vials, containing 10 mL in each vial as a sterile solution and is intended to be diluted prior to infusion. Components of AVB-S6-500 Study Drug include: AVB-S5-600, the active component, at a concentration of 20 mg/ml_ (±2 mg/ml_); 0.01% stabilizer and anti-oxidant polysorbate-80,

10 mM buffer mono and disodium phosphate, and 9% stabilizer sucrose. Subjects will be treated with 6 doses of AVB-S6-500, administered on Day 1 and every other week thereafter, totaling 12 weeks of treatment (6 doses) Patients will be followed throughout week 16.

[00118] Safety assessment will include evaluation of AEs using the Common

Terminology Criteria for Adverse Events (CTCAE v 4.03), clinical laboratory results, vital sign measurements, 12-lead ECG measurements, and physical examination. AEs will be coded using the MedDRA dictionary and CMs using the WHO Drug dictionary.

[00119] Blood samples for plasma pharmacokinetics (AVB-S6-500) and

pharmacodynamics (GAS6) analysis will be collected after the first and fourth doses at the following time points relative to dosing (pre-dose (within 45 minutes before dosing), at the following post-dose time points: 1 , 4, 8 and 336 hours (which should be immediately before the 2^nd dose).

[00120] The pharmacologic effect of AVB-S6-500 will be assessed on the change from baseline in proteinuria and mesangial cell proliferation. Serum GAS6 data and proteinuria levels will also be analyzed.

[00121] Because AVB-S6-500 targets GAS6 and inhibits the AXL signaling implicated in mesangial cell kidney disease and because GAS6 expression correlates with severity of IgAN and decreased proteinuria improves survival in IgAN, the present inventors expect that treatment with AVB-S6-500 will decrease proteinuria and potentially prolong time to requiring dialysis as compared to control. As such, AVB-S6-500 and related proteins present a new and effective treatment for IgAN.

[00122] All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

[00123] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible. It is also understood that the terminology used herein is for the purposes of describing particular embodiments.

[00124] Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to one of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or only and is not intended to limit the scope of the present invention which will be limited only by the appended claims.

[00125] Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the appended claims.

Sequence Listings

[00126] The nucleic and amino acid sequences listed in the accompanying sequence listing are shown using standard letter abbreviations for nucleotide bases and three letter code for amino acids, as defined in 37 C.F.R. 1.822.

SEQ ID NO: 1 - Human AXL polypeptide amino acid sequence

MGRVPLAWCLALCGWACMAPRGTQAEESPFVGNPGNITGARGLTGTLRCQLQVQGEPPEVH

WLRDGQILELADSTQTQVPLGEDEQDDWIVVSQLRITSLQLSDTGQYQCLVFLGHQTFVSQPG

YVGLEGLPYFLEEPEDRTVAANTPFNLSCQAQGPPEPVDLLWLQDAVPLATAPGHGPQRSLH

VPGLNKTSSFSCEAHNAKGVTTSRTATITVLPQQPRNLHLVSRQPTELEVAWTPGLSGIYPLTH

CTLQAVLSNDGMGIQAGEPDPPEEPLTSQASVPPHQLRLGSLHPHTPYHIRVACTSSQGPSSW

THWLPVETPEGVPLGPPENISATRNGSQAFVHWQEPRAPLQGTLLGYRLAYQGQDTPEVLMD

IGLRQEVTLELQGDGSVSNLTVCVAAYTAAGDGPWSLPVPLEAWRPGQAQPVHQLVKEPSTP

AFSWPWWYVLLGAVVAAACVLILALFLVHRRKKETRYGEVFEPTVERGELVVRYRVRKSYSRR

TTEATLNSLGISEELKEKLRDVMVDRHKVALGKTLGEGEFGAVMEGQLNQDDSILKVAVKTMK

lAICTRSELEDFLSEAVCMKEFDHPNVMRLIGVCFQGSERESFPAPVVILPFMKHGDLHSFLLYS

RLGDQPVYLPTQMLVKFMADIASGMEYLSTKRFIHRDLAARNCMLNENMSVCVADFGLSKKIY NGDYYRQGRIAKMPVKWIAIESLADRVYTSKSDVWSFGVTMWEIATRGQTPYPGVENSEIYDY

LRQGNRLKQPADCLDGLYALMSRCWELNPQDRPSFTELREDLENTLKALPPAQEPDEILYVNM

DEGGGYPEPPGAAGGADPPTQPDPKDSCSCLTAAEVHPAGRYVLCPSTTPSPAQPADRGSP

AAPGQEDGA

SEQ ID NO: 2 - Exemplary soluble AXL polypeptide-Fc fusion.

EESPFVSNPGNITGARGLTGTLRCQLQVQGEPPEVHWLRDGQILELVDSTQTQVPLGEDEQG

DWIVASQLRITSLQLSDTGQYQCLVFLGHQTFVSQPGYVRLEGLPYFLEEPEDRTVAANTPFNL

SCQAQGPPEPVDLLWLQDAVPLATAPGHGPQRSLHVPGLNKTSSFSCEAHNAKGVTTSRTATI

TVLPQQGGGGSDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPE

VKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEK

TISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPV

LDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG

Claims

What is claimed is:

1. A method for treating immunoglobulin A nephropathy (IgAN) in a patient comprising administering to said patient a therapeutically effective dose of a soluble AXL variant

polypeptide according to a regimen determined to reduce proteinuria compared to control (baseline prior to treatment).

2. The method according to claim 1 wherein proteinuria is reduced by at least about 10% to at least about 90% compared to control.

3. The method according to claim 1 wherein proteinuria is reduced by at 10% to at least compared to control.

4. The method according to claim 1 wherein proteinuria is reduced by at 20% to at least compared to control.

5. The method according to claim 1 wherein proteinuria is reduced by at 30% to at least compared to control.

6. The method according to claim 1 wherein proteinuria is reduced by at 40% to at least compared to control.

7. The method according to claim 1 wherein proteinuria is reduced by at 50% to at least compared to control.

8. A method for treating immunoglobulin A nephropathy (IgAN) in a patient comprising administering to said patient a therapeutically effective dose of a soluble AXL variant

polypeptide according to a regimen determined to prolong time to requiring dialysis as compared to control.

9. A method according to any one of claims 1 -8, wherein the dose of the soluble AXL variant polypeptide administered to the patient is selected from the group consisting of about 0.5, of about 1.0, of about 1.5, of about 2.0, of about 2.5, of about 3.0, of about 3.5, of about 4.0, of about 4.5, of about 5.0, of about 5.5, of about 6.0, of about 6.5, of about 7.0, of about 7.5, of about 8.0, of about 8.5, of about 9.0, of about 9.5, of about 10.0 mg/kg, of about 10.5, of about 1 1 .0, of about 1 1.5, of about 12.0, of about 12.5, of about 13.0, of about 13.5, of about 14.0, of about 14.5, of about 15.0, of about 15.5, of about 16.0, of about 16.5, of about 17.0, of about 17.5, of about 18.0, of about 18.5, of about 19.0 mg/kg, of about 19.5, and of about 20.0 mg/kg.

10. A method according to claim 9, wherein the soluble AXL variant polypeptide is administered as an IV infusion at a weekly dose of 15 mg/kg.

1 1 . A method according to claim 9, wherein the soluble AXL variant polypeptide is administered as an IV infusion at a weekly dose of 12.5 mg/kg.

12. A method according to claim 9, wherein the soluble AXL variant polypeptide is administered as an IV infusion at a weekly dose of 10 mg/kg.

13. A method according to claim 9, wherein the soluble AXL variant polypeptide is administered as an IV infusion at a weekly dose of 7.5 mg/kg.

14. A method according to claim 9, wherein the soluble AXL variant polypeptide is administered as an IV infusion at a weekly dose of 5 mg/kg.

15. A method according to any one of claims 1 -14, wherein the dose is given biweekly.

16. A method according to any one of claims 1 -14, wherein the dose is given once every three weeks.

17. A method according to any one of claims 1 -14, wherein the dose is given monthly.

18. A method according to any one of claims 1 -17, wherein the soluble AXL variant polypeptide lacks the AXL transmembrane domain; lacks a functional fibronectin (FN) domain; has one or more than one Ig1 domain and, optionally, one or more than one Ig2 domain; and has a set of amino acid modifications of the wild-type AXL sequence (SEQ ID NO:1 ), selected from the group consisting of: 1 ) Gly32Ser, Asp87Gly, Val92Ala, and Gly127Arg,

2) Glu26Gly, Val79Met, Val92Ala, and Gly127Glu; and

3) Gly32Ser, Ala72Val, Asp87Gly, Val92Ala, and Gly127Arg;

wherein said modification increases the affinity of the AXL polypeptide binding to Growth arrest- specific protein 6 (GAS6).

19. A method according to claim 18, wherein the soluble AXL variant polypeptide is fused to an Fc region.

20. A method according to claim 19, wherein the soluble AXL variant polypeptide comprises the amino acid sequence set forth in SEQ ID NO: 2.

21 . A method according to any one of claims 1 -20, further comprising: a) testing a sample from the patient for the presence of a GAS6 biomarker; and b) adjusting the dose of the soluble AXL variant polypeptide based on the presence or absence of the GAS6 biomarker.

22. A method according to any one of claims 1 -21 , wherein the soluble AXL variant is administered in combination with a second anti-lgAN therapy.