Rheumatoid Arthritis and Treatments

Question 1

what is RA?

Answer 1

RA is the commonest cause of chronic inflammatory polyarthritis
- Effects many joints
- Tends to affect synovial joints and joints of hands and feet
- Prevalent in 0.5-1% of worldwide population, with 3:1 bias towards women

Question 2

what is the normal synovial joint like?

Answer 2

Yellow thin layer on inside of joint capsule = synovial membrane
- Synovial membrane produces nutrition for joint and lubricin for motility of joint

Question 3

what happens in the RA synovial joint?

Answer 3

Synovial layer is thickened and inflamed in RA patient
- Thickened synovial layer has infiltration and proliferation of macrophages, fibroblasts, T cells, B cells and plasma cells
- Not many neutrophils in synovial layer, but many in synovial fluid – neutrophils traffic through
- Leading edge of synovial layer is the pannus, which interacts with and erodes bone and cartilage – irreversible loss and thinning of joint space

Question 4

what are the two layers in the rheumatoid synovium?

Answer 4

Intimal lining layer = normally 2-3 cell layers thick, but expanded in RA

Sublining layer = influx of monocytes/macrophages and T lymphocytes

Question 5

how were autoantibodies identified in RA patients?

Answer 5

Take sheep red blood cells (SRBCs) and coat with serum from rabbits (antibodies bind SRBCs) and add serum from RA patients
- RBCs form agglutinated clumps
- The target of the autoantibodies that cause agglutination is the Fc region of IgG which bound the rabbit serum

Question 6

is RA purely immune-complex mediated?

Answer 6

Rheumatoid factor (RF) and other autoantibodies form immune complexes that deposit in RA joint and lead to complement activation to attract neutrophils and inflammatory cells – inflamed synovium
- But RF can be formed without RA
RF may be important in clearing immune complexes following infection
- RA is not purely immune-complex mediated

Question 7

what HLA molecules are implicated in RA?

Answer 7

HLA-DR class II associations with RA, particularly in HLA-DR4 and HLA-DR1 molecules
- Not every DR4 and DR1 subtype was associated with RA
- Those subtypes that were associated with RA shared a common amino acid sequence that sat in the peptide binding groove of HLA molecule
- This is the shared epitope
- These associated DR molecules may present similar peptides to each other
- Maybe RA is T-cell mediated

Question 8

are T cells important in RA?

Answer 8

Prominent T cell infiltrate
Collagen-induced arthritis (CIA) and adjuvant-induced arthritis (AIA) are T cell dependent

BUT
- T cell cytokines IL-2 and IFNγ low in RA joint
- Macrophage and fibroblast cytokines higher in RA joint-
- Apparent low efficacy of T cell therapies (e.g. ciclosporin, anti-CD4 or anti-CD5 antibodies)
- Anti-CD52 is also ineffective (alemtuzumab) – T cell depleting antibody
Maybe T cells don’t drive the disease

Question 9

what are cytokine networks?

Answer 9

Concept of cytokine networks
- Dysregulation of the cytokine environment may drive RA and be self-perpetuating
- High levels of IL-6 released by activated fibroblasts can activate macrophages.
- Macrophages release more cytokines that further activate fibroblasts.
- T cells feed into this with their own cytokine production

Question 10

what cytokines have been shown to be master regulators in RA joint?

Answer 10

Took small synovium samples from patient joints and cultured in vitro
- Looked at cytokine production
- Showed high levels of IL-1
- When they gave anti-TNF treatment, levels of IL-1 went down

Targeting a single cytokine may not actually be redundant
- Targeting master regulator cytokines like TNF can dampen down the rest of the cytokine network

Question 11

how is TNF implicated in RA?

Answer 11

High levels of TNF in RA joint
- Major source are monocytes/macrophages
- TNF is a key regulator of other pro-inflammatory cytokines and up-regulates adhesion molecules – enables immune infiltration
- Activates leukocytes, endothelial cells and synovial fibroblasts
- Promotes angiogenesis of the thickened synovial layer by stimulating VEGF production
- Induces osteoclast differentiation and inhibits osteoblast formation - facilitates bone erosion and prevents bone healing
- Depression and fatigue?

Question 12

how is IL-6 implicated in RA?

Answer 12

Large amounts in RA synovium
- Drives proliferation and differentiation of B cells and T cells
- Pivotal regulator of T cell migration and activation
- Promotes acute phase response and fever
- Acute phase response – more inflammatory markers, loss of weight, fever
- Drives osteoclast differentiation
- also upregulates VEGF production

Question 13

how is GM-CSF implicated in RA?

Answer 13

Indcuces activation and pro-inflammatory differentiation of: Macrophages, Neutrophils, Dendritic cells
- Administration of GM-CSF to treat neutropenia promotes disease flare
- RA patients can be neutropenic and be more susceptible to infections, so treated with GM-CSF to increase neutrophil count
- This can promote disease flare

Question 14

what different autoantibodies are in RA?

Answer 14

RF is associated with RA, but not always in RA patients and can be other patients
- anti-perinuclear factor antibodies
- anti-keratin antibodies
- anti-filaggrin

Question 15

how were anti-perinuclear antibodies and anti-keratin antibodies tested for?

Answer 15

Test for anti-perinuclear factor
Sensitivity was less than RF but more specific to RA patients
- Anti-PF is more likely to be seen only in RA patients compared to other diseases
- Took buccal cells from mouth, put on slide, added RA patient serum, washed off and targeted any bound PF antibodies with immunofluorescent anti-IgG
- Green dots indicate presence of anti-RF

Test for anti-keratin antibodies
Used rat oesophagus
Inside of oesophagus lights up for presence of anti-K antibodies in RA serum

Question 16

what antigen was targeted in both the anti-perinuclear factor and anti-keratin antibodies tests?

Answer 16

Antigen targeted in both of these tests was filaggrin
- Filaggrin is a protein found in skin, not in RA joint - suggests cross-reactivity
- Researchers made recombinant filaggrin and tried to use in ELISA/WB
- Found that RA serum didn’t bind recombinant filaggrin
- This suggests that what was important in the antibody binding to filaggrin was a PTM

Question 17

what PTM occurs to filaggrin in the RA joint?

Answer 17

The PTM is citrullination – conversion of arginine to citrulline residues
- This normally occurs in myelin sheath to make it waterproof, occurs as skin develops in uppermost layers, occurs at sites of inflammation

Question 18

how was the anti-CCP test developed?

Answer 18

Took small peptide from filaggrin containing citrulline amino acids
- Used anti-CCP1 test which has higher sensitivity than anti-PF/K antibodies and also great specificity for RA

Took panel of artificially-made peptides in which they inserted citrulline residues
- Found combination of peptides which had highest sensitivity and specificity for RA sera
- This was the anti-CCP2 assay

Question 19

what are anti-CCP2 antibodies?

Answer 19

Sensitivity 70-80% and specificity 95% - high sensitivity and specificity for RA

Useful diagnostic and prognostic tool:
- a patient presenting with new inflammatory arthritis and with anti-CCP are more likely to develop RA
- Progression of undifferentiated arthritis to RA
- with anti-CCP, RA patients tend to have higher disease activity, more bone erosions and more extra-articular manifestations

Can RA be subdivided into those with anti-CCP and those without?
- But because anti-CCP2 were targeting artificial peptides, this test doesn’t give info on in vivo antigens that are targeted

Question 20

what are the non-genetic, environmental RA risk factors?

Answer 20

Smoking, silica, air-pollution - promote citrullination in lung and drive ACPA

Hormonal risk factors:
- RA less likely to occur when women are pregnant, but more likely just after birth
- Increased accumulative time that women spend breastfeeding reduces RA risk

Infections can trigger RA – hard to prove:
- anti-CCP can occur years before RA onset, and the infectious trigger would’ve therefore also occurred years prior to onset, so hard to prove this

Inflamed gums and loss of teeth = periodontitis:
- Suggested that this is risk factor for RA
- Bacteria in periodontitis can potentially cause citrullination – potential risk factor

Question 21

how can genetic and environmental risk factors combine in RA?

Answer 21

Looked at smoking and HLA-DRB1 shared epitope as risk factors
- in anti-CCP negative RA, there is little influence of shared epitope and/or smoking on increased risk/odds ratio for RA
anti-CCP positive RA patients:
- Smoking and no shared epitope = slightly increased risk
- Shared epitope 1 copy and smoking = increased risk
- 2 copies and smoking = massive increased risk

Gene environment interaction as risk factor for development of autoantibodies and subsequent RA

Question 22

what are other genetic risk factors for RA?

Answer 22

ACPA positive: PTPN22, CTLA4, TRAF1-C5, c-REL

ACPA negative: HLA-DRB1*03
IRF5, C-type lectin domain factor 5

There are many other genetic risk factors – over 100
- Some risk factors are ACPA positive, some are ACPA negative some may be in both groups
These risk factors may represent two broad subsets of disease with different pathogenic processes

Question 23

ACPA are potentially important in pathogenesis of RA and strongly associated, but do they drive disease process?

Answer 23

• Precursors for osteoclasts express PAD4 enzyme
• PAD4 promotes citrullination
• Osteoclast precursors express citrullinated vimentin on their surface
• Citrullinated vimentin bind anti-CCP2 and triggers osteoclast precursor to produce more TNF
• TNF drives differentiation to osteoclasts – ACPA may therefore speed up bone loss and stimulate pro-inflammatory cytokine release

Question 24

what experiments were performed to assess IL-23 in RA?

Answer 24

Took animal models of RA and created them in WT mice and mice which lacked IL-23
- IL-23 is important for Th17 differentiation
- In CIA and KBxN models, there is lower onset of inflammatory arthritis in mice with IL-23 K/O or anti-IL-23
- Reduced induction of RA when IL-23 is deficient

antibody-induced arthritis from CIA or KBxN:
- Transfer serum into WT mouse = developed arthritis
- Transfer serum into IL-23 K/O mice = developed arthritis the same
- Similarly, anti-IL-23 in serum-transfer had no impact on arthritis induction

Question 25

what does IL-23 contribute to in RA?

Answer 25

IL-23 contributes to the initiation but not the effector phase of autoantibody-mediated arthritis - IL-23 may be causing antibodies to become pathogenic - But when antibodies are already pathogenic, IL-23 has no further role in pathogenesis - Therefore, IL-23 has a role in induction of RA, not the effector phase or persistence

Question 26

how does IL-23 drive pathogenic antibodies?

Answer 26

IL-23 drives Th17 differentiation: - Th17 in germinal centre causes alteration of antibody glycosylation taking place in plasmoblasts - In presence of IL-23 and Th17 cells, there is loss of sialic acid residues on the antibody Fc region due to glycosylation Took antibodies from mice where they had induced arthritis and been given IL-23 - They transferred serum into WT mice with anti-IL-23 = reduction in disease severity and onset - Treatment of serum with neuraminidase (removes sialic acid from glycosylation) = these antibodies were more pathogenic and drove disease Process of IL-23-driven inflammation alters glycosylation status and turns autoantibodies more pathogenic

Question 27

can reduced sialylation be seen in the ACPA of human patients?

Answer 27

In humans, ACPA can be found in patients years before RA onset - Obtained serum from ACPA-positive patients with mild symptoms - Looked at patients over time - Divided groups into those who developed RA within 12 months of serum being taken and those who didn’t develop RA - Patients who went on to develop RA had lower sialic acid on their antibodies than those who didn’t develop RA Altered glycosylation may convert lesser pathogenic autoantibodies into more pathogenic which can trigger clinical RA onset

Question 28

what are the clinical features of RA?

Answer 28

- Swollen joints – knuckles, fingers - Joint destruction and erosion, loss of joint space, disability - can see erosions via radiography and ultrasound - with ultrasound, can see increased blood flow in joint – thickened synovium needs its own blood flow, gained via angiogenesis - Untreated RA can also lead to accelerated CVD and extracellular manifestations e.g. vasculitis, skin ulcers, rash, interstitial lung disease

Question 29

when do joint erosions occur?

Answer 29

Joint erosions occur early in course of RA - Up to 93% of patients with <2 years of RA may have radiographic abnormalities (old data, the stats are better now) - majority of patients have erosions early on - Erosions can be detected by MRI within 4 months of RA onset - Rate of progression is significantly more rapid in the first year than in the second and third years

Question 30

what are the therapeutic goals for RA?

Answer 30

Control signs and symptoms Prevention of structural damage Limit loss of function, wellbeing and premature death - Untreated RA is associated with earlier loss of life Cure? - Cure currently is aspirational - We have made progress in managing symptoms, but if treatment is removed, RA comes back - Need to switch process off entirely so patient can go drug free for many years

Question 31

how should RA be managed?

Answer 31

Erosions occur early: need Early referral, early diagnosis, early treatment Window of opportunity concept: - 2 cohorts of patients, one group treated early in disease, other group with delayed treatment Y axis = sharp score = measure of joint damage - Group with delayed 3-month treatment had worse joint damage at 2 years, even though the treatments are the same - early delays in treatment can lead to worse outcome - Intense treatment early can change course of disease - treatments with concept of treat-to-target: escalate treatment

Question 32

how is RA classified?

Answer 32

RA has phenotypic classification - Doesn’t take into account the molecular pathways active in the joint - Simply counts involved joints, considers positive autoantibody tests, duration of symptoms (whether its persistent beyond 6 weeks), whether there are acute phase reactants - This phenotypic classification allows identification of those in early disease course for earlier treatment to control disease early on

Question 33

what treatments are used to start with in newly diagnosed RA patients?

Answer 33

Disease-modifying anti-rheumatic drugs (DMARDs) - A drug is classed as a DMARD if in clinical trials it controls inflammatory symptoms in joint and prevents structural bone erosion and loss of joint space – prevents joint damage 4 common DMARDs - methotrexate - first-line - hydroxychloroquine (HCQ)

Question 34

what is methotrexate?

Answer 34

Methotrexate is an old drug - First developed as they found folic acid is important for cancer growth - In animal models, giving folic acid makes cancer grow quicker, and reducing folic acid slows cancer progression - Methotrexate developed as anti-folate agent (folate antagonist) for cancer treatment - Then 4 randomised control trials confirmed methotrexate to be effective in RA

Question 35

why is methotrexate good for RA treatment?

Answer 35

RA almost universally is a persistent disease which rarely remits without treatment – progressive - Often patients with ongoing joint swelling, treatments would be introduced slowly - Patients presenting with new RA are likely to progress and worsen over time - urgency to treat early - Methotrexate is now first-like DMARD in UK

Question 36

how does methotrexate work in cancer? what side effects does it cause?

Answer 36

Methotrexate is a folate antagonist - It effects rapidly dividing cells – used to treat cancer - Side effects = oral ulcers, dysrepsia (altered lining of stomach), loss of rapidly proliferating cells in bone marrow (risk in patients with renal impairment as they can’t metabolise methotrexate so the drug builds up), alopecia as it affects hair growth

Question 37

how is methotrexate given in RA?

Answer 37

Doses that work RA are lower than those used to inhibit rapid cellular proliferation in cancer - The day after giving methotrexate, RA patients are given folic acid to reduce side effects, but doesn’t reduce methotrexate efficacy

Question 38

how may methotrexate work to treat RA?

Answer 38

Methotrexate mechanisms are complex - different hypotheses for RA - Methotrexate stimulates production of adenosine - Methotrexate is taken up into cells and converted to methotrexate polyglutamate - This inhibits action of AICAR transformase enzyme - Inhibition of AICAR transformase leads to increased AICAR levels, which inhibits AMP deaminase, which in turn increases cellular AMP levels within the cell which increases adenosine production - Adenosine is released from cells and has potent anti-inflammatory effect - Adenosine is short lived – works in paracrine manner

Question 39

how has the adenosine mechanism of methotrexate been shown?

Answer 39

Some data supports: - Model of inflammation, created air pouches with inflammation-inducing substance - Measure no. white cells within pouches - Steroid dex reduces no. white cells, as does methotrexate - Repeated the experiment but with adenosine receptor (A2A or A3) K/O mice - Found that steroids continued to reduce no. white cells within air pouches, whereas methotrexate no longer had effect - Suggests that methotrexate works via activation of adenosine receptors

Question 40

can methotrexate be combined with anti-TNF?

Answer 40

Clinical trial - Took newly presenting RA patients and randomised into 3 groups: MTX alone, anti-TNF alone or both - Anti-TNF alone and MTX alone had similar no. of patients achieving clinical remission at year 1 and year 2 - Combination caused much higher clinical remission rates Although MTX works well in reducing clinical symptoms, its not as good as anti-TNF in preventing bone erosion - But MTX is good in RA overall

Question 41

when can corticosteriods be used to treat RA?

Answer 41

- If patient has a single problematic joint, we can inject steroids into that joint to reduce inflammation – intra-articular - Give pulse of corticosteroids when patient first comes to clinic during induction period of DMARDs as DMARDs have slow action at first or because of disease flare - Some patients with severe disease may be given low dose of oral steroids long term, which can cause slowing of radiographic joint damage and control symptoms

Question 42

what biological DMARDs are available?

Answer 42

anti-TNF, 5 different versions Rituximab Abatacept Tocilizumab - good efficacy in RA, bind IL-6R

Question 43

what are the 5 versions of anti-TNF?

Answer 43

Infliximab – murine Fv region Adalimumab – humansied Fv region Golimumab – fully human Certolizumab – takes humanised Fv regions and binds to polyethylene glycol – smaller construct so better synovial access Etanercept – takes 2P75 TNFRs and bind to Fc region of IgG to prolong half-life

Question 44

what is rituximab

Answer 44

Anti-CD20 mAb depleting antibody Kills B cells from pre-B-cell to pre-plasma cell Selectivel oss of virtually all B lineage blood cells Germinal centre B cells resistant - Some germinal centre B cells are resistant – may have reduced effect in some patients

Question 45

is rituximab effective in RA?

Answer 45

Clinical benefit comparable to anti-TNF Usual regime is 2 infusions 2 weeks apart Repeat courses as required but no greater than 6 monthly Efficacious in anti-TNF failures

Question 46

what is abatacept?

Answer 46

Abatacept – CTLA-4-Ig blocks co-stimulatory signal to T cells T cell co-stimulation is required for APC to activate a T cell - co-stimulation via CD28-CD80/86 leads to T cell activation and CTLA-4 upregulation at surface - CTLA-4 competes with CD28 for CD80/86 to inhibit T cell - Abatacept is recombinant CTLA-4 bound to Fc region of IgG to prolong half life - Abatacept competes with CD28 to bind to CD80/86 to prevent T cell activation - acts as decoy to downregulate co-stim

Question 47

why is it hard to get new drugs for RA?

Answer 47

Showing that a new drug works isn’t enough – it needs phase 3 programme and convince that its safe and better than current drugs - Why is the new drug better and should be used? - Safer? Long-term safety data set needed - Better and more effective than other drug? - Targets different pathway to other drugs? - Target comorbidity? In RA, patients can have osteoporosis, CVD risk, fatigue – does drug treat these?

Question 48

how is drug efficacy measured in RA? how does this effect drug choice in the clinic?

Answer 48

'Ceiling’ of efficacy in traditional randomised control trials: ACR response is a response to several measures ACR20 ≈ in 60% patients - 20% improvement in at least 3 of those measures ACR50 ≈ 40% - 50% improvement ACR70 ≈ in 20% patients - 70% improvement most clinical trials look similar in RA, where most drugs have similar efficacy - Drug choice in clinic often relates to order of historical licensing and cost, not patient factors - hence why methotrexate is first-line as it was first licensed, then other drugs like anti-TNF used

Question 49

how can patients be stratified based on ACR?

Answer 49

individual immunological profiles affect responses - 60% of people get 20% better What about the other 40%? - is a different drug gonna work? Hard to pick these patients out Rituximab depletes B cells - More effective in ACPA+ and RF+ RA - these are more likely to respond Abatacept has greater drug retention and efficacy in antibody-positive patients - antibody-negative patients do worse on abatacept

Question 50

how does RF levels impact longevity of anti-TNF use?

Answer 50

RF binds Fc region of antibody and forms immune complexes - Does RF+ patient affect efficacy of biologics? Yes Certolizumab: Anti-TNF lacks Fc region and only has the Fv components which are pegylated (bound to PEG molecule) - increases size of molecule to prolong half-life - RF+ patients have better survival with this drug compared to adalimumab (normal anti-TNF)

Question 51

what are anti-drug antibodies?

Answer 51

If patient is given biologics, some patients develop immune response to drug where anti-drug-antibodies stop the drug working - doesn't cause side effects - Etanercept (lacks Fv region, has Fc region bound to two two P75 TNFRs - fusion molecule) generates less anti-drug antibodies so is better and enables longer survival

Question 52

can RA patients be defined molecularly?

Answer 52

Subdivide patients based on genetics: -100 SNPs give risk for RA – most related to immune system e.g. cytokines, B cells, T cells - can select patients with certain polymorphisms to enable drug selection e.g. a patient with many polymorphisms with T cells means to use abatacept - But this hasn’t worked – no molecular signature available to tie drug to efficacy in RA

Question 53

how can RA patients be stratified based on tissue?

Answer 53

Take synovial tissue from RA patients: - RA is a phenotypic description – just symmetrical swollen joints clinically – not based on histological or immunological description of joint In RA tissue: 1st group = lymphoid infiltrate bias, TLs, T and B cell aggregates and GC response 2nd group = predominant activation of myeloid cells - macrophages 3rd group = fibroblast-type (poor-sign immune) proliferation of synovial fibroblasts mostly Maybe these group pathotypes respond to different treatments

Question 54

how do patients respond to rituximab depending on their tissue type?

Answer 54

Took patients who failed anti-TNF - Took synovial biopsy – grouped patients into B cell poor and rich - ypothesised that B cell rich patients should have better response to rituximab compared to anti-IL-6 - Patients randomised Found that: - looked for 50% improvement at week 16 using histological and RNA seq classification (bulk sequencing) - Hisologically: B cell-poor with anti-IL-6R had 56% response, with rituximab = 45% response - RNA seq: showed more difference than histology: B cell poor: response to rituximab was only 36%, whereas 63% for anti-IL-6R double response to tocilizumab in B cell poor patients compared to rituximab

Question 55

how may disease stages of RA affect drug choice?

Answer 55

Drugs in RA may depend on disease stage - Cytokines in RA may have effect depending on disease stage IL-23 can be targeted in psoriatic arthritis, but not RA - IL-23 can drive changes in glycosylation status of antibodies - ACPA can be found 10 years before symptoms - Profile of ACPA change over time – their glycosylation status changes - More sialylation which increases ability to activate immune response – this is IL-23 driven - Blocking IL-23 early on is effective in preventing pathogenic ACPA, but with established RA IL-23 blockade has no effect

Question 56

what is the APIPPRA trial?

Answer 56

Want to prevent development of full RA - Some patients have ACPA year before symptoms – may have a resolving form early on with relapsing-remitting joint pain, which eventually develops to persistent disease – window of opportunity to treat early and switch off disease APIPPRA trial: - recruited patients who had inflammatory joint symptoms without joint swelling and ACPA positive - given abatacept for 1 year vs placebo - Transition to RA was limited in pre-RA patients given abatacept - Delays development of RA, but doesn’t stop it developing entirely if drug removed - patients with lots of ACPA, there is still an large effect of abatacept 2 years later - Often when drug is removed, most patient relapse - 60% relapse within first few months - Not curable – drug needs to be maintained

Question 57

what enzymes do cytokines signal through?

Answer 57

Cytokines signal via receptor-mediated activation of JAK (tyrosine kinase enzyme) - JAKs phosphorylate tyrosine residue on the receptor, causing conformational change recruit STATs and allow them to bind - STATs get phosphorylated and dimerise to translocate into the nucleus and drive gene transcription

Question 58

what are the different types of JAKs?

Answer 58

4 JAKs: JAK1-3 and TYK2 cross-over: Type 1 IFN use JAK1 and TYK2 JAK2 blocks EPO and TPO hormones

Question 59

what is tofacitinib?

Answer 59

JAK1 and JAK3 inhibitor - pan-JAK inhibitor - used in the clinic

Question 60

is tofacitinib better than adalimumab?

Answer 60

when assessing drug induced remission: - Highest dose of Tof outperforms Ada in causing remission and outperforms Ada in preventing erosions

Question 61

what are the other JAK inhibitors?

Answer 61

JAK1 – Filgotinib, Upadacitinib - more specific JAK1/2 – Baricitinib JAK3 – Peficitinib (licensed in Japan 2019), Decernotinib in development

Question 62

are JAK inhibitors safe?

Answer 62

Cytokine networks in RA: anti-TNF gives effective blockade or TNF without affecting other cytokines - pan-JAK inhibitor inhibits many cytokine signalling pathways, but at low doses to avoid too much cytokine inhibition - High dose increases risk of infection - Tof blocks JAK1 which is needed for IFN1 – impairs viral immunity, so may lead to viral reactivation - Increased risk of cancer, CVD events with JAKi as it downregulates immuno-surveillance - Black box warning with JAKi for malignancy and CVD - Anti-TNF can reduce risk of cancer in certain settings – unclear - maybe its that anti-TNF is preventing cancer, rather than JAKi causing cancer - JAKi can increase risk of thromboembolism (lung clot)

Question 63

what is TLL-018?

Answer 63

combined JAK1/TYK2 inhibitor - Improves ACR50 response in 72% patients compared to Tof (41%) - But small study

Question 64

what are melanocortins?

Answer 64

melanocortin receptor (MC): endogenous anti-inflammatory and pro-resolving mediators - - allows us to promote resolution of inflammation rather than treat inflammation - MC receptors important to stimulate body’s production of steroids, which may have side effects

Question 65

what is the difference between MC2 and MC1/3/4/5?

Answer 65

- activation by ACTH of MC2 in adrenal cortex enables corticosteroid production and downstream steroid-dependent effects - activation of MC1/3/4/5 cause steroid-independent effects - Activation MC3 - activate pro-resolution effects without increased steroid production in body. Induces macrophages to do efferocytosis to clean up debris in the joint, switches off NF-kB signalling to reduce pro-inflammatoy cytokine release

Question 66

how effective is MC3R in mouse models?

Answer 66

MC3 is increased in resolution phase of KBxN serum transfer model - MC3 mRNA increased in joints during disease resolution - In group with K/O MC3, worse and persistent arthritis and erosion, more RANKL - Activation of MC3 can promote resolution - MC3R promotes macrophage phenotype which increases clearance of damage and reduces inflammation

Question 67

has MC3 activity shown success in humans?

Answer 67

MC3 agonist has shown to be promising in doubling response rates (61%) compared to placebo (33%) - human trial

Question 68

how can fibroblasts be targeted?

Answer 68

Synovial fibroblasts proliferate due to CDK4/6 - Can target CDK4/6 to prevent proliferation and inflammation - CDK4/6 are genetic variants for RA in GWAS study - CDK4/6 inhibition abrogates joint damage in mouse model - Culture RA fibroblasts with CDK4/6 inhibitors can reduce their inflammatory gene expression and their pro-inflammatory state

Question 69

why may CDK4/6 inhibitors limited for RA?

Answer 69

But CDK4/6 can cause neutropenia and has bad side effects in cancer Looks safer in RA – TCK-276 small molecule inhibitor of CDK4/6 causes no neutropenia in phase 1b trial

Question 70

what is otilimab? was it successful?

Answer 70

Otilimab blocks GM-CSF - GM-CSF important for macrophage and neutrophil proliferation and activation Phase 3 trial with >3000 patients - High placebo response - Two doses of otilimab compared to placebo – it does work, but not that much better - And its not as good as tof Otilimab therefore wasn’t licensed for RA - Need to show good efficacy and other features, not just that it works

Question 71

what are TPH cells?

Answer 71

Peripheral T helper cell (Tph) subset in RA: - TFH cells found in GCs - TPH cells are found outside GC response in the periphery - many of these found in RA synovium - Highly express PD-1, produce IL-21, CXCL13 – B cell attraction and activation - These are B cell supporting cells PD1 is downregulatory switch of T cells: Improves cancer outcomes with ICB - But proportion of ICB-treated cancer patients get RA - Blocking PD1 can induce RA, so PD-1 agonist may be useful to treat RA

Question 72

what drug is a PD-1 agonist and was it successful?

Answer 72

PD1-agonist: Peresolimab Phase 2a data - Shows good response and reduces disease activity compared to placebo - Good in patients with failed previous biologic use Phase 2b study failed – not sure why BUT: PD-1 agonist may increase risk of cancer and injection

Question 73

is ACPA a bystander or does it drive pathogenesis of RA?

Answer 73

ACPA binding to vimentin can accelerate osteoclast formation - Immune complexes with CCPs can active synovial fibroblasts and macrophages - This is all debated though

Question 74

how is the FcRn neonatal Fc receptor implicated in RA?

Answer 74

IgG half-life extended due to FcRn - Monocytes/macrophages and endothelial cells have FcRn - These cells constantly process blood proteins - Endothelial cells pinocytose protein, protein enters endolysosome to be broken down to peptide - If FcRn is present in endosome, then IgG binds and is protected from degradation and recycled to cell surface - Also helps FcyR in antigen presentation and processing Therefore, an antibody that blocks FcRn will block IgG recycling and reduces autoantibdoy titer

Question 75

what is an example of an FcRn antibody drug?

Answer 75

Nipocalimab - Small study in RA - Did have effect - suggests that IgG may be directly pathogenic in RA - Combination with anti-TNF also been studied

Question 76

why could PAD enzyme inhibition be used in RA?

Answer 76

PAD enzymes drive citrullination - PAD2 and PAD4 levels and PAD enzymic activity are increased in patient serum compared to healthy controls. - small molecules have been ineffective as they're not specific to PAD - AZD1163 is a novel anti-PAD2/4 bi-specific antibody that binds with high affinity with Fc region mutations to promote FcRn recycling and to suppress C1q and FcγR-mediated effector functions - AZD1163 inhibits all endogenous PAD activity in the RA serum and synovial fluid in vitro - In animal model anti-PAD2/4 reduced severity of CIA, even though citrullination isn’t as important in CIA

Question 77

how have antibody-drug conjugates been used in RA?

Answer 77

ADC specific to TNF - TNF goes to sites of inflammation - Payload of GCCR modulator – steroid effects without side effects - Bind steroid-like molecule to anti-TNF – precise GCC effect localised at sites of inflammation with high TNF

Question 78

how does the immune system and CNS overlap?

Answer 78

- Sites of inflammation activate autonomic nervous system - Vagus nerve – afferent branch takes signal to brain - Signals down vagus parasympathetic nerve that downregulates inflammation via cholinergic reflex - Vagus efferent nerve can reduce cytokine production via activation of a7 subunit of AChR on macrophages in spleen or joint, or fibroblast-like synoviocytes in joint - Vagus nerve doesn't innervate the spleen, so likely that the sympathetic nerve goes to spleen and releases noradrenaline – binds to T cells, activates choline acetyltransferase, leads to release of ACh that binds and downregulates macrophage function - Nervous system can reduce inflammation

Question 79

how has neurostimulation been used in RA?

Answer 79

Vagus nerve stimulators - Small devices that can be wirelessly recharged are implanted next to vagus nerve - Can give stimulation to downregulate immune response In a group of therapy-resistant RA patients: - This stimulation reduced disease activity - Small study