INTRODUCTION [0001] The present invention relates to therapeutic compounds. More specifically, the present invention relates to compounds that are modulators of IL-17A activity. The present 5 invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of diseases or disorders associated with IL-17A activity. BACKGROUND OF THE INVENTION [0002] The interleukin-17 cytokine family consists of six members (termed IL-17A 10 through IL-17F) of which IL-17A (also known as CTLA-8) is the primary effector cytokine of the T-helper-17 (Th17) cell lineage. [0003] IL-17A is a variably glycosylated, disulfide linked, homodimeric glycoprotein of 34-38 kDa which shares in the order of 50% homology with its closest family member IL- 17F, both of which can be secreted either as homodimers or the heterodimer IL-17AF [K.F. 15 Geoghegan et al., Protein Expression and Purification 2013, 87, 27-34; J.K. Kells and A. Linden/Immunity 2004, 21, 467-476]. [0004] Activation of na"lve CD4+ T-cells in response to cytokines such as IL-6, transforming growth factor 13 (TGF-(3), IL-23, STAT3, and RORyt leads to their differentiation to TH17 cells and expression of pro-inflammatory mediators such as IL-17A. 20 Furthermore, a variety of cell types from the innate and adaptive immune systems have been identified as sources of IL-17A. These include mast cells, neutrophilic granulocytes, NK cells, NKT cells, CD8+ T cells, oy T-cells, macrophages, and type 3-innate lymphoid cells [D.J. Cua and C.M. Tato, Nat Rev lmmunol 2010, 10, 479-489; W. Jin and C. Dong, Emerging Microbes & Infections 2013, 2, e60]. 25 [0005] Cytokines IL-17A, IL-17F and IL-17AF bind to common heteromeric receptor complexes IL-17RA and IL-17RC, albeit with different affinities, and although various cell types have been reported to express the IL-17RA subunit, the highest responses to IL-17A come from epithelial cells, endothelial cells, keratinocytes, and fibroblasts [T.A. Moseley et ai./Cytokine Growth Factor Reviews. 2003, 14, 155-174; S.L. Gaffen/ Nature Rev 30 lmmunol 2009, 9, 556-567; R.M. Onishi and S.L. Gaffen/ Immunology 2010, 129, 311- 321]. [0006] Binding of IL-17A to its receptor activates various signal transduction pathways such as nuclear factor (NF)-KB, phosphoinositide 3-kinase (PI3K), activator protein (AP1), wo 2021/239743 2 PCT/EP2021/063934 CCAAT/enhancer-binding protein (C/EBP), and mitogen-activated protein kinase (MAPK) leading to pro-inflammatory gene expression and the secretion of various pro-inflammatory cytokines including IL-1(3, IL-6, IL-8, TNFa, G-CSF, PGE2, and IFN-y as well as numerous chemokines and other effectors [S.L. Gaffen, Arthritis Research & Therapy 2004, 6, 240- 5 247; S.L. Gaffe, Nature Rev lmmunol 2009, 9, 556-567; R.M. Onishi and S.L. Gaffen, Immunology 2010, 129, 311-321]. The attraction and activation of cells of the innate immune system to the site of inflammation completes the induction of an inflammatory loop which may also be mediated cooperatively with other cytokines such as TN Fa, IFN-y, and IL-113 [S.L. Gaffen, Arthritis Research & Therapy 2004, 6, 240-247]. 10 [0007] These IL-17 mediated biological processes have been implicated in the pathology of many human diseases with an immune component or autoimmune pathology, such as psoriasis, ankylosing spondylitis, axial spondyloarthritis, psoriatic arthritis, eczema, enthesitis-related arthritis, asthma (including severe asthma), chronic obstructive pulmonary disease (COPD), cystic fibrosis, pulmonary fibrosis, ulcerative colitis, Crohn's 15 disease, atopic dermatitis, contact dermatitis, dermatomyositis, myocarditis, uveitis, exophtalmos, autoimmune thyroiditis, Peyronie's disease, coeliac disease, gall bladder disease, Pilonidal disease, peritonitis, multiple sclerosis, Guillan-Bar Syndrome, irritable bowel syndrome, inflammatory bowel disease, Castleman's disease, pelvic inflammatory disease, systemic onset juvenille idiopathic arthritis (JIA), rheumatoid arthritis, giant cell 20 arteritis, graft versus host disease, discoid lupus erythematosus, systemic lupus erythematosus, lupus nephritis, vasculitis, insulin dependent diabetes type I, autoimmune diabetes, Necrobiosis Lipoidica Diabeticorum, Pyoderma Gangrenosum, Hidradenitis Suppurativa, Papulopustular Rosacea, Lichen Planus, heart disease including ischaemic diseases such as myocardial infarction as well as atherosclerosis, intravascular 25 coagulaton, bone resorption, osteroporosis, peridontitis, hypochlorhydria, pain (particularly pain associated with inflammation), and also in cancer (Bartlett, HS; Million, RP (2015) Nat. Rev. Drug Discovery 14:11-12; Santibanez, JF; Bjelica, S (2018) Recent Pat Anticancer Drug Discov. 13(2):133-144). In addition, due to the emerging role of neuroinflammation in neurodegeneration, IL-17 has also been implicated in the 30 progression of neurodegenerative disorders such as Alzheimer's disease (Cristiano et al (2019) Br J Pharmacal. 176(18):3544-3557) and Parkinson's disease (Storelli et al, (2019) Front Neurol. 24;10:13). Furthermore, due to IL-17A's key regulatory roles in host defense pathological conditions of relevance also include viral, bacterial, fungal and parasitic infections. An association between serum levels of IL-17 at the time of admission to the 35 intensive care unit and the development of sepsis has also been observed suggesting increased IL-17 may increase the susceptibility for septic complications and endotoxic wo 2021/239743 3 PCT/EP2021/063934 shock associated with infection [Ahmed et al., Eur J Trauma Emerg Surg 2018, 44(4):621- 626]. Its role in sepsis has also been suggeted to extend to patients with sepsis-induced Acute Respiratory Distress Syndrome (ARDS) and acute lung injury [Ding et al., Oncotarget 2017, 8(55):93704-93711]. Very recently inhibition of IL-17 has also been 5 suggested to be used to prevent acute respiratory distress syndrome (ARDS) in coronavirus disease 2019 (COVID-19) [Pacha, Sallman & Evans., Nat Rev lmmunol 2020, 1:1-2]. [0008] Pre-clinical studies have demonstrated that IL-17A (as well as IL-17F and IL-17C) is elevated in psoriatic skin [N.J. Wilson et al., Nat lmmunol 2007, 8, 950-957; L.C. Zaba 10 et al., J Exp Med 2007, 204, 3183-3194; C. Ortega et al, J Leukocyte Biol2009, 86, 435- 443; C. Johansen et al., Br J Dermatol 2009, 160, 319-324]. Th17 cells in the peripheral circulation and lesional skin of patients with psoriasis have also been shown to positively correlate with disease severity as measured by the Psoriasis Area and Severity Index (PASI) score [L. Zhang et al., Clin lmmunol2010, 135, 108-117]. Serum IL-17A levels are 15 also significantly correlated with PASI score [H. Takahashi et al., Clin Exp Dermatol2010, 35, 645-649; S.B. Yilmaz et al. Arch Dermatol Res 2012, 304, 465-469; M. Caproni et al., J Clin lmmunol2009, 29, 210-214]. [0009] Animal model studies supported the hypothesis that targeting the IL-17A pathway would be an effective treatment for psoriasis [L. van der Fits et al., J lmmunol 2009, 182, 20 5836-5845; K. El Malki etal., J lnvestig Dermatol2013, 133, 441-451; J. Skepneretal., J lmmunol 2014, 192, 2564-2575] and clinical results with antibodies to IL-17A or IL-17RA delivered the ultimate validation with excellent efficacy being observed [R.G. Langley et al., N Engl J Med 2014, 371, 326-338; K.B. Gordon et al., N Engl J Med 2016, 375, 345- 356; A.S. Lonnberg et al., Clin Cosmet lnvestig Dermatol 2014, 7, 251-259; S. Coimbra et 25 al., Core Evid 2014, 9, 89-97; M. Lebwohl et al., N Engl J Med 2015, 373, 1318-1328]. [0010] Elevated levels of IL-17A or IL-17F have been reported in a number of other diseases including Rheumatoid Arthritis (RA), Psoriatic Arthritis (PsA), Ankylosing Spondylitis (AS), Systemic Lupus Erythematosus (SLE), Inflammatory Bowel Disease (lBO), Multiple Sclerosis (MS), bone erosion, intraperitoneal abscesses, allograft rejection, 30 angiogenesis, atherosclerosis, and asthma [e.g. S.L. Gaffen, Arthritis Research & Therapy 2004, 6, 240-247; L.A. Tesmer et al., lmmunol Rev 2008, 223, 87-113; US Publ No 20080269467]. [0011] The anti-IL-17A therapeutic antibodies Secukinumab and lxekizumab have shown evidence of positive effects in treating palmoplantar and nail psoriasis; [A. Gottlieb 35 et al., J Am A cad Dermatol 2016, 76, 70-80; A. Menter et al., J Eur Acad Dermatol Venereal wo 2021/239743 4 PCT/EP2021/063934 2017, 31, 1686-1692; C. Paul et al., J Eur Acad Dermatol Venereol2014, 28, 1670-1675]; PsA [P. Mease et al., Ann Rheum Dis 2018, 77, 890-897; P. Nash et al., Lancet 2017, 389, 2317-2327] and AS [K. Pavelka et al., Arthritis Res Ther 2017, 19, 285; A. Deodhar et al., Arthritis Rheumatol 2018, doi: 10.1 002/art.40753]. A proof of concept study with 5 Secukinumab in MS has also shown encouraging signs of efficacy [E. Havdrova et al., J Neurol 2016, 263, 1287-1295]. [0012] IL-17A expression has been shown to be increased in SLE patients and correlated with disease severity [Y. Wang et al., Clin Exp lmmunol2009, 159, 1-10; X.Q. Chen et al., J Clin lmmunol2010, 30, 221-225]. 10 [0013] In addition, IL-17A has been associated with ocular surface disorders such as DES [PCT publications W02009089036, W0201 0062858 and W02011163452; C.S. De Paiva et al., Mucosallmmunol 2009, 2, 243-253] and Th17 cells have been shown to be elevated in active uveitis and scleritis [A. Amadi-Obi et al., Nat Med 2007, 13, 711-718]. IL-17A levels in tears were associated with clinical severity of dry eye in patients with a 15 range of systemic autoimmune or inflammatory diseases including Sjogren's syndrome, Stevens-Johnson syndrome (SJS), SLE, filamentary keratitis, DES, Meibomian gland dysfunction (MGD), and Graft-versus-Host disease (GVHD) [M.H. Kang et al., J Korean Med Sci 2011, 26, 938-944]. [0014] Several studies have demonstrated that IL-17A is overexpressed in patients with 20 a range of cancers including gastric carcinoma, medulloblastoma, multiple myeloma, colorectal carcinoma, Non-Small-Cell Lung Cancer (NSCLC), breast cancer, hepatocellular carcinoma (HCC), and thyroid cancer [X. Meng et al., Turk J Gastroenterol 2018, 29, 45-51; P. Zhou et al., J lnt Med Res 2010, 38, 611-619; D. Lemancewicz et al., Med Sci Monit 2012, 18, BR 54-59; S. Le Gouvello et al., Gut 2008, 57, 772-779; B. Pan 25 et al., Sci Rep 2015, 5, 16053; T. Welte and X. H-F. Zhang, Mediators Inflammation 2015, 804347; J-F. Tu et al., Medicine (Baltimore) 2016, 95, e3220; D.F.G. Carvalho et al., Oncol Lett 2017, 13, 1925-1931]. Increased levels of IL-17A have been shown to correlate with poor prognosis in several cancer types including malignant thyroid tumor, breast cancer, pancreatic carcinoma, gastric cancer, NSCLC, colorectal cancer, and head and neck 30 cancer [S. Punt et al., Oncolmmunol2015, 4, e984547; D.F.G. Carvalho et al., Oncol Lett 2017, 13, 1925-1931; W-C. Chen et al., Histopathology 2013, 63, 225-233; C. Xu et al., Biomarkers 2014, 19, 287-290; Y. Yamada et al., J Surg Res 2012, 178, 685-691; S. He et al., lnt J Mol Sci 2011, 12, 7424-7437; J-Y. Tseng et al., Clin Cancer Res 2014, 20, 2885-2897; M-H. Lee et al., Oncotarget 2018, 9, 9825-9837]. wo 2021/239743 5 PCT/EP2021/063934 [0015] Taken together, modulation of the IL-17A pathway, in particular modulation of IL- 17A activity through inhibition of its interaction with the receptor IL-17RA, may be considered a target for the treatment of conditions relating to the immune system and inflammation, cancer and neurodegenerative disorders. 5 [0016] WO 2013/116682, WO 2014/066726 and WO 2018/229079 describe classes of chemical compounds that are stated to modulate the activity of IL-17 and to be useful in the treatment of medical conditions, including inflammatory disease. [0017] Nevertheless, there is an ongoing need for compounds capable of attenuating IL- 17 A activity. 10 SUMMARY OF THE INVENTION [0018] In one aspect, the present invention provides a compound, or a pharmaceutically acceptable salt thereof as defined herein. [0019] In another aspect, the present invention provides a pharmaceutical composition 15 comprising a compound of the invention as defined herein, or a pharmaceutically acceptable salt thereof, and one or more pharmaceutically acceptable excipients. [0020] In another aspect, the present invention relates to a compound of the invention as defined herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as defined herein, for use in therapy. 20 [0021] In another aspect, the present invention relates to a compound of the invention as defined herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as defined herein, for use in the treatment of diseases or disorders associated with I L -17 A activity. [0022] In another aspect, the present invention relates to the use of a compound of the 25 invention as defined herein, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for use in the treatment of diseases or disorders associated with I L -17 A activity. [0023] In another aspect, the present invention relates to a method of treating a disease or disorder associated with IL-17A activity, said method comprising administering to a 30 subject in need of such treatment a therapeutically effective amount of a compound of the invention as defined herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as defined herein. [0024] Examples of diseases or disorders associated with IL-17A activity include diseases with an immune component or autoimmune pathology (such as psoriasis, wo 2021/239743 6 PCT/EP2021/063934 ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis), cancer and neurodegenerative disorders. [0025] In another aspect, the present invention provides a compound, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as defined 5 herein, for use in the treatment of diseases with an immune component or autoimmune pathology (such as psoriasis, ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis), cancer, and neurodegenerative disorders. [0026] In another aspect, the present invention provides the use of a compound, or a pharmaceutically acceptable salt, in the manufacture of a medicament for use in the 10 treatment of diseases with an immune component or autoimmune pathology (such as psoriasis, ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis), cancer, and neurodegenerative disorders. [0027] In another aspect, the present invention provides a method of treating diseases with an immune component or autoimmune pathology (such as psoriasis, ankylosing 15 spondylitis, psoriatic arthritis, and rheumatoid arthritis), cancer, and neurodegenerative disorders, said method comprising administering to a subject in need of such treatment a therapeutically effective amount of a compound, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as defined herein. [0028] The present invention further provides a method of synthesising a compound, or 20 a pharmaceutically acceptable salt thereof, as defined herein. [0029] In another aspect, the present invention provides a compound, or a pharmaceutically acceptable salt thereof, obtainable by, or obtained by, or directly obtained by a method of synthesis as defined herein. [0030] In another aspect, the present invention provides novel intermediates as defined 25 herein which are suitable for use in any one of the synthetic methods set out herein. [0031] Preferred, suitable, and optional features of any one particular aspect of the present invention are also preferred, suitable, and optional features of any other aspect. DETAILED DESCRIPTION OF THE INVENTION Definitions 30 [0032] Unless otherwise stated, the following terms used in the specification and claims have the following meanings set out below. [0033] It is to be appreciated that references to "treating" or "treatment" include prophylaxis as well as the alleviation of established symptoms of a condition. "Treating" wo 2021/239743 7 PCT/EP2021/063934 or "treatment" of a state, disorder or condition therefore includes: (1) preventing or delaying the appearance of clinical symptoms of the state, disorder or condition developing in a human that may be afflicted with or predisposed to the state, disorder or condition but does not yet experience or display clinical or subclinical symptoms of the state, disorder or 5 condition, (2) inhibiting the state, disorder or condition, i.e., arresting, reducing or delaying the development of the disease or a relapse thereof (in case of maintenance treatment) or at least one clinical or subclinical symptom thereof, or (3) relieving or attenuating the disease, i.e., causing regression of the state, disorder or condition or at least one of its clinical or subclinical symptoms. 10 [0034] A "therapeutically effective amount" means the amount of a compound that, when administered to a mammal for treating a disease, is sufficient to effect such treatment for the disease. The "therapeutically effective amount" will vary depending on the compound, the disease and its severity and the age, weight, etc., of the mammal to be treated. [0035] In this specification the term "alkyl" refers to aliphatic hydrocarbon groups and 15 includes both straight and branched chain alkyl groups. References to individual alkyl groups such as "propyl" are specific for the straight chain version only and references to individual branched chain alkyl groups such as "isopropyl" are specific for the branched chain version only. For example, "C1-6alkyl" includes C1-4alkyl, C1-3alkyl, propyl, isopropyl and t-butyl. A similar convention applies to other radicals, for example "phenyiC1-6alkyl" 20 includes phenyiC1-4alkyl, benzyl, 1-phenylethyl and 2-phenylethyl. [0036] The term "alkylene" includes both straight and branched chain divalent alkyl groups. For example, "C1-4alkylene" includes methylene (-CH2-), ethylene (-CH2CH2-), propylene and butylene. [0037] The term "alkoxy" includes both straight and branched chain alkyl groups 25 singularly bonded to oxygen. For example, "C1-4alkoxy" includes methoxy, ethoxy, isopropoxy and t-butoxy. [0038] The term "Cm-n" used as a prefix, refers to any group having m to n carbon atoms. [0039] "Cycloalkyl" means a hydrocarbon ring containing from 3 to 8 carbon atoms, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl or 30 bicycle[2.2.2]octane, bicycle[2.1.1]hexane, bicycle[1.1.1]pentane and bicyclo[2.2.1]heptyl. [0040] The term "halo" refers to fluoro, chloro, bromo and iodo. [0041] The term "haloalkyl" or "haloalkoxy" is used herein to refer to an alkyl or alkoxy group respectively in which one or more hydrogen atoms have been replaced by halogen (e.g. fluorine) atoms. Examples of haloalkyl and haloalkoxy groups include fluoroalkyl and wo 2021/239743 8 PCT/EP2021/063934 fluoroalkoxy groups such as -CHF2, -CH2CF3, or perfluoroalkyl/alkoxy groups such asCF3, -CF2CF3 or -OCF3. [0042] The term "carbocyclyl", "carbocyclic" or "carbocycle" means a non-aromatic saturated or partially saturated monocyclic, or a fused, bridged, or spiro bicyclic carbocyclic 5 ring system(s). Monocyclic carbocyclic rings contain from about 3 to 12 (suitably from 3 to 7) ring atoms. Bicyclic carbocycles contain from 7 to 17 carbon atoms in the rings, suitably 7 to 12 carbon atoms, in the rings. Bicyclic carbocyclic rings may be fused, spiro, or bridged ring systems. [0043] The term "heterocyclyl", "heterocyclic" or "heterocycle" means a non-aromatic 10 saturated or partially unsaturated monocyclic, fused, bridged, or spiro bicyclic heterocyclic ring system(s). Monocyclic heterocyclic rings contain from about 3 to 12 (suitably from 3 to 7) ring atoms, with from 1 to 5 (suitably 1, 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur in the ring. Bicyclic heterocycles contain from 7 to 17 member atoms, suitably 7 to 12 member atoms, in the ring. Bicyclic heterocyclic(s) rings may be fused, 15 spiro, or bridged ring systems. Examples of heterocyclic groups include cyclic ethers such as oxiranyl, oxetanyl, tetrahydrofuranyl, dioxanyl, and substituted cyclic ethers. Heterocycles containing nitrogen include, for example, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, tetrahydrotriazinyl, tetrahydropyrazolyl, and the like. Typical sulfur containing heterocycles include tetrahydrothienyl, dihydro-1 ,3-dithiol, tetrahydro-2H-thiopyran, and 20 hexahydrothiepine. Other heterocycles include dihydro-oxathiolyl, tetrahydro-oxazolyl, tetrahydro-oxadiazolyl, tetrahydrodioxazolyl, tetrahydro-oxathiazolyl, hexahydrotriazinyl, tetrahydro-oxazinyl, morpholinyl, thiomorpholinyl, tetrahydropyrimidinyl, dioxolinyl, octahydrobenzofuranyl, octahydrobenzimidazolyl, and octahydrobenzothiazolyl. For heterocycles containing sulfur, the oxidized sulfur heterocycles containing SO or S02 25 groups are also included. Examples include the sulfoxide and sulfone forms of tetrahydrothienyl and thiomorpholinyl such as tetrahydrothiene 1, 1-dioxide and thiomorpholinyl 1, 1-dioxide. A suitable value for a heterocyclyl group which bears 1 or 2 oxo (=0) or thioxo (=S) substituents is, for example, 2-oxopyrrolidinyl, 2-thioxopyrrolidinyl, 2-oxoimidazolidinyl, 2-thioxoimidazolidinyl, 2-oxopiperidinyl, 2,5-dioxopyrrolidinyl, 30 2,5-dioxoimidazolidinyl or 2,6-dioxopiperidinyl. Particular heterocyclyl groups are saturated monocyclic 3 to 7 membered heterocyclyls containing 1, 2 or 3 heteroatoms selected from nitrogen, oxygen or sulfur, for example azetidinyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidinyl, morpholinyl, tetrahydrothienyl, tetrahydrothienyl 1,1- dioxide, thiomorpholinyl, thiomorpholinyl 1, 1-dioxide, piperidinyl, homopiperidinyl, 35 piperazinyl or homopiperazinyl. Partially unsaturated heterocyclyl rings contain at least one double bond, such as 1 or 2 double bonds. Examples of partially unsaturated wo 2021/239743 9 PCT/EP2021/063934 heterocyclyl rings include 1 ,6-dihydropyridinyl, 1 ,6-dihydropyridazinyl and 2,3- dihydropyrrolyl. As the skilled person would appreciate, any heterocycle may be linked to another group via any suitable atom, such as via a carbon or nitrogen atom. Suitably, the term "heterocyclyl", "heterocyclic" or "heterocycle" will refer to 4, 5, 6 or 7 membered 5 monocyclic rings as defined above. [0044] By "bridged ring systems" is meant ring systems in which two rings share more than two atoms, see for example Advanced Organic Chemistry, by Jerry March, 4th Edition, Wiley lnterscience, pages 131-133, 1992. Examples of bridged heterocyclyl ring systems include, aza-bicyclo[2.2.1 ]heptane, 2-oxa-5-azabicyclo[2.2.1 ]heptane, aza- 1 0 bicyclo[2.2.2]octane, aza-bicyclo[3.2.1]octane and quinuclidine. [0045] By "spiro bi-cyclic ring systems" we mean that the two ring systems share one common spiro carbon atom, i.e. the heterocyclic ring is linked to a further carbocyclic or heterocyclic ring through a single common spiro carbon atom. Examples of spiro ring systems include 6-azaspiro[3.4]octane, 2-oxa-6-azaspiro[3.4]octane, 2- 15 azaspiro[3.3]heptanes and 2-oxa-6-azaspiro[3.3]heptanes. [0046] The term "heteroaryl" or "heteroaromatic" means an aromatic mono-, bi-, or polycyclic ring incorporating one or more (for example 1-4, particularly 1, 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur. Examples of heteroaryl groups are monocyclic and bicyclic groups containing from five to twelve ring members, and more 20 usually from five to ten ring members. The heteroaryl group can be, for example, a 5- or 6-membered monocyclic ring or a 9- or 1 0-membered bicyclic ring, for example a bicyclic structure formed from fused five and six membered rings or two fused six membered rings. Each ring may contain up to about four heteroatoms typically selected from nitrogen, sulfur and oxygen. Typically the heteroaryl ring will contain up to 3 heteroatoms, more usually up 25 to 2, for example a single heteroatom. In one embodiment, the heteroaryl ring contains at least one ring nitrogen atom. The nitrogen atoms in the heteroaryl rings can be basic, as in the case of an imidazole or pyridine, or essentially non-basic as in the case of an indole or pyrrole nitrogen. In general the number of basic nitrogen atoms present in the heteroaryl group, including any amino group substituents of the ring, will be less than five. Heteroaryl 30 groups containing nitrogen atoms may be present as the corresponding N-oxides. Particular examples of such heteroaryl groups are pyridine N-oxides. Suitably, the term "heteroaryl" or "heteroaromatic" will refer to 5 or 6 membered monocyclic heteroaryl rings as defined above. CLAIMS 1. A compound of Formula I wherein: 0 (I) 0 X1, X2, X3, and X4 are each independently CR5 or N; Y is aryl or heteroaryl, each of which is optionally substituted by one or more substituents independently selected from halo, C1-4alkyl, C1-4alkoxy, C1- 3alkylene-C1-4alkoxy, C1-2alkylene-N(C1-3alkyl)2, and C1-4haloalkyl; and wherein when Y is a 5- or 6-membered heteroaryl ring, said ring is optionally fused to a 5- or 6-membered cycloalkyl or heterocyclyl ring, each of which is optionally substituted by one or more substituents independently selected from from halo, C1-4alkyl, C1-4alkoxy, C1-3alkylene-C1-4alkoxy, C1-2alkyleneN( C1-3alkyl)2, and C1-4haloalkyl; R1 and R2: (A) are both phenyl optionally substituted with one or more substituents independently selected from halo, C1-4alkyl, C1-4alkoxy, and C1- 4haloalkyl, and wherein the phenyl groups are optionally linked by a bond or a C1-2alkylene moiety; OR (B) together with the carbon atom to which they are attached form a 4- to 10-membered cycloalkyl or a 4- to 10-membered heterocyclyl ring, wherein the cycloalkyl or heterocyclyl ring: a. is optionally substituted with one or more substituents independently selected from halo, C1-4alkyl, C1-4alkoxy, C1- 4haloalkyl, and C1-4haloalkoxy; b. optionally comprises one or two C=C double bonds; c. is optionally bridged by a C1-3alkylene group connecting two carbon atoms of the ring; and d. is optionally spiro-attached to one or more independently selected C3-scycloalkyl groups; 5 10 15 20 25 30 35 wo 2021/239743 278 PCT/EP2021/063934 R3 is hydrogen, fluoro, or C1-4alkyl; R4 is: (A) a 5- to 10-membered heteroaryl, a C3-7cycloalkyl, or a 3- to 12- membered heterocyclyl ring, each of which is optionally substituted by one or more substituents independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1-3alkylene-R11, C3-7cycloalkyl, and heterocyclyl, wherein said C3-7cycloalkyl and heterocyclyl substituents are optionally substituted with one or more substituents independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , and C02R10; (B) (C) (D) (E) C1-6alkyl optionally substituted with hydroxy, halo, C1-4alkoxy, cyano, NR6R7, C(O)NR8R9 or C02R10; 5- to 6-membered heteroaryl ring, said ring being fused to a 5- or 6- membered cycloalkyl or heterocyclyl ring, each of which is optionally substituted by one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano NR6R7, C(O)NR8R9 , C02R10 , C1-3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; a 5- or 6-membered cycloalkyl or a 5- or 6-membered heterocyclyl ring, said ring being fused to a phenyl or 5- to 6-membered heteroaryl ring, each of which rings is optionally substituted by one or more substituents independently selected from halo, oxo, C1-4alkyl, C1- 4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1_ 3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; OR a partially unsaturated heterocyclic ring, optionally fused to a 5- to 6- membered heteroaryl ring and optionally substituted with one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1_ 3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; R5 is hydrogen, halo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl or cyano; R11 is hydroxy, halo, C1-4alkoxy, cyano, NR12R13, C(O)R14, aryl or heteroaryl; R14 is hydroxy, C1-4alkyl, C1-4alkoxy or NR15R16; R6, R7, R8 , R9 , R10 , R12, and R13 are independently selected from hydrogen and C1- 4alkyl; R15 and R16 are independently selected from hydrogen and C1-4alkyl; or wo 2021/239743 279 PCT/EP2021/063934 5 2. 10 3. 4. 5. 6. 15 7. 20 8. R15 and R16, taken together with the nitrogen atom to which they are attached, form a 3- to ?-membered heterocyclyl ring, the ring optionally containing a further heteroatom chosen from 0, S, and Nand being optionally substituted with C1- 4alkyl; or a pharmaceutically acceptable salt thereof. The compound according to claim 1, having the following structure: R2 0 wherein X1, X2, X3, X4, Y, R1, R2, R3, and R4 are as defined in claim 1; or a pharmaceutically acceptable salt thereof. The compound according to claim 1 or claim 2, wherein X1, X2, X3, and X4 are each independently CH or N. The compound according to claim 3, wherein X1 is Nand X2, X3, and X4 are CH. The compound according to claim 3, wherein X1, X2, X3, and X4 are all CH. The compound according to claim 1 or claim 2, wherein two of X1, X2, X3, and X4 are CR5, and two are N; or three of X1, X2, X3, and X4 are CR5, and the other is N. The compound according to any one of claims 1 to 6, wherein Y is heteroaryl optionally substituted by one or more substituents independently selected from halo, C1-4alkyl, C1-4alkoxy, C1-3alkylene-C1-4alkoxy, C1-2alkylene-N(C1-3alkyl)2, and C1- 4haloalkyl. The compound according to claim 7, wherein Y is a 5- or 6-membered heteroaryl ring, said ring being optionally fused to a 5- or 6-membered cycloalkyl or heterocyclyl ring, each of which is optionally substituted by one or more substituents independently selected from halo, C1-4alkyl, C1-4alkoxy, C1-3alkylene-C1-4alkoxy, C1- 2alkylene-N(C1-3alkyl)2, and C1-4haloalkyl. wo 2021/239743 280 PCT/EP2021/063934 9. The compound according to claim 7, wherein Y is a heteroaryl ring optionally substituted by one or more substituents independently selected from halo, C1-3alkyl, C1-2alkoxy, C1-2alkylene-C1-2alkoxy, and C1-2haloalkyl. 10. The compound according to claim 7, wherein Y is a 5- to 6-membered heteroaryl 5 optionally substituted by one or more substituents independently selected from halo and methyl. 10 11. The compound according to claim 7, wherein Y is a 5- to 6-membered heteroaryl ring substituted in a position ortho to the NHC(O)- moiety by methyl or ethyl. 12. The compound according to any one of claims 1 to 6, wherein Y is: ))N ~0 N or wherein J"IJVV' is the point of attachment to the rest of the compound of Formula I and Y is optionally substituted by one or more substituents independently selected from halo, C1-3alkyl, C1-2alkoxy, C1-2alkylene-C1-2alkoxy, and C1-2haloalkyl. 13. The compound according to any one of claims 1 to 12, wherein R1 and R2 are both 15 phenyl optionally substituted with one or more substituents independently selected from fluoro and methyl. 20 25 14. The compound according to any one of claims 1 to 12, wherein R1 and R2 together with the carbon atom to which they are attached form a 5- to 8-membered cycloalkyl ring, wherein the cycloalkyl ring: a. is optionally substituted with one or more substituents independently selected from halo, C1-2alkyl, C1-2alkoxy, and C1-2haloalkyl; b. optionally comprises one or two C=C double bonds; c. is optionally bridged by a C1-3alkylene group connecting two carbon atoms of the ring; and d. is optionally spiro-attached to a C3-scycloalkyl group. wo 2021/239743 281 PCT/EP2021/063934 15. The compound according to any one of claims 1 to 12, wherein R1 and R2 together with the carbon atom to which they are attached form a group selected from: wherein * is the carbon atom to which R1 and R2 are attached, each occurrence of 5 R17 is independently selected from halo, C1-2alkyl, C1-2alkoxy, and C1-2haloalkyl, and m is 0,1, 2 or3. 16. The compound according to any one of claims 1 to 12, wherein R1 and R2 together with the carbon atom to which they are attached form the following group: 10 wherein * is the carbon atom to which R1 and R2 are attached, and each R17 is independently selected from hydrogen, fluoro, methyl, and trifluoromethyl. 17. The compound according to any one of claims 1 to 16, wherein R3 is hydrogen. 18. The compound according to any one of claims 1 to 17, wherein R4 is: (A) a 5- to 10-membered heteroaryl or C3-7cycloalkyl ring, each of which 15 is optionally substituted by one or more substituents independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1-3alkylene-R11 , C3-7cycloalkyl, and heterocyclyl, wherein said C3-7cycloalkyl and heterocyclyl substituents are optionally substituted with one or more substituents 20 (B) (C) 25 independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1- 4haloalkyl, cyano, NR6R7, C(O)NR8R9 , and C02R10; C1-6alkyl optionally substituted with hydroxy, halo, C1-4alkoxy, cyano, NR6R7 or C02R10; 5- to 6-membered heteroaryl ring, said ring being fused to a 5- or 6- membered cycloalkyl or heterocyclyl ring, each of which is optionally wo 2021/239743 5 (D) 10 (E) 282 PCT/EP2021/063934 substituted by one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1-3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; a 5- or 6-membered cycloalkyl or a 5- or 6-membered heterocyclyl ring, said ring being fused to a phenyl or 5- to 6-membered heteroaryl ring, each of which rings is optionally substituted by one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1_ 3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; or a partially unsaturated heterocyclic ring, optionally fused to a 5- to 6- membered heteroaryl ring and optionally substituted with one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1_ 15 3alkylene-R11, C3-7cycloalkyl, and heterocyclyl. 20 25 30 35 19. The compound according to any one of claims 1 to 17, wherein R4 is: (A) a 5- to 10-membered heteroaryl or C3-7cycloalkyl ring, each of which is optionally substituted by one or more substituents independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1-3alkylene-R11 , C3-7cycloalkyl, and heterocyclyl, wherein said C3-7cycloalkyl and heterocyclyl substituents are optionally substituted with one or more substituents independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1- 4haloalkyl, cyano, NR6R7, C(O)NR8R9 , and C02R10; (C) (D) 5- to 6-membered heteroaryl ring, said ring being fused to a 5- or 6- membered cycloalkyl or heterocyclyl ring, each of which is optionally substituted by one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1-3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; a 5- or 6-membered cycloalkyl or a 5- or 6-membered heterocyclyl ring, said ring being fused to a phenyl or 5- to 6-membered heteroaryl ring, each of which rings is optionally substituted by one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9 , C02R10 , C1_ 3alkylene-R11, C3-7cycloalkyl, and heterocyclyl; or wo 2021/239743 283 PCT/EP2021/063934 (E) a partially unsaturated heterocyclic ring, optionally fused to a 5- to 6- membered heteroaryl ring and optionally substituted with one or more substituents independently selected from hydroxy, halo, oxo, C1-4alkyl, C1-4alkoxy, C1-4haloalkyl, cyano, NR6R7, C(O)NR8R9, C02R10 , C1_ 5 3alkylene-R11, C3-7cycloalkyl, and heterocyclyl. 20. The compound according to any one of claims 1 to 17, wherein R4 is a 5- to 10- membered heteroaryl, C3-7cycloalkyl, or 3- to 12-membered heterocyclyl ring, each of which is optionally substituted by one or more substituents independently selected from hydroxy, halo, C1-4alkyl, C1-4alkoxy, C1-2fluoroalkyl, cyano, NR6R7, C(O)NR8R9, 10 and C1-3alkylene-R11 . 21. The compound according to claim 19, wherein R4 is a 5- to 6-membered monocyclic heteroaryl ring, or a 9- to 1 0-membered bicyclic heteroaryl ring, optionally substituted by one or more substituents independently selected from fluoro, chloro, methyl, methoxy, trifluoromethoxy, cyano, NR6R7, cyclopropyl, and CH2-R11 . 15 22. The compound according to claim 19, wherein R4 is a partially unsaturated 23. 20 heterocyclic ring, optionally fused to a 5- to 6-membered heteroaryl ring and optionally substituted with one or more substituents independently selected from hydroxy, halo, oxo, C1-2alkyl, C1-2alkoxy, C1-2haloalkyl, and cyano. The compound according to any one of claims 1 to 17, wherein R4 is selected from one of the following groups: cY cY ~ R19-NQ OQ N~~ -o.........-N~~ N~\N (R18)p (R18)p (R18)p (R18)p (R18)p sQ R19 R19 'NJ (