POS0856 DEFINING THE CLINICAL UTILITY OF PET OR PET/CT IN IDIOPATHIC INFLAMMATORY MYOPATHIES: A SYSTEMATIC LITERATURE REVIEW

Background

Positron emission tomography (PET), now often combined with computed tomography (CT), is a well-established tool for evaluating malignancy and inflammatory disease. The idiopathic inflammatory myopathies (IIM) are chronic, multi-system diseases characterised by skeletal muscle inflammation, the potential for extramuscular manifestations such as interstitial lung disease (ILD) and an increased risk of malignancy. PET or PET/CT thus has appeal as an imaging modality that may permit simultaneous assessment of multiple features of IIM, however its role in evaluation of these diseases remains poorly defined.

Objectives

This systematic review seeks to evaluate and describe the utility of PET or PET/CT in IIM, specifically for the detection of inflammatory muscle pathology, associated malignancy and extramuscular manifestations (e.g. ILD).

Methods

We performed a search of Medline and EMBASE from 1990-2021 using keywords related to IIM and PET. We included English language studies of adults with IIM who had PET or PET/CT as part of their diagnostic workup.

Results

Our search identified 910 potentially relevant abstracts, 18 of which were included.

The majority of studies used fluorodeoxyglucose (FDG) PET or PET/CT scans, while the remainder used other radiotracers including [18F] florbetapir and [11C] Pittsburgh compound B ([11C] PIB).

1.Malignancy – PET vs. conventional screening

Six studies investigated the ability of 18F-FDG PET or 18F-FDG PET/CT to detect malignancy in people with IIM. When reported, the sensitivity and specificity of PET or PET/CT for diagnosing malignancy compared with standard detection methods was 66.7-94% and 88.9-97.8%, respectively.

2.ILD

Using high-resolution CT (HRCT) as the gold standard for detection of ILD, three studies reported the ability of PET or PET/CT to detect ILD. The sensitivity of 18F-FDG PET alone for ILD was 39%, while the sensitivity of 18F-FDG PET/CT for ILD was 93-100%. FDG lung uptake was significantly increased in people with rapidly progressive-ILD (RP-ILD) in comparison to those with non-RP-ILD in two studies.

3.Muscle disease activity

Ten studies evaluated either 18F-FDG PET or 18F-FDG PET/CT for its ability to detect muscle inflammation in IIM. In the nine studies where controls were used, PET or PET/CT appeared to accurately detect the presence of muscle inflammation, although correlations with clinical measures of myositis disease activity such as strength and serum creatine kinase were mixed.

4.A word on amyloid

Skeletal muscle amyloid deposition was evaluated using [11C]PIB-PET in two studies and [18F] florbetapir PET/CT in one study. In all three studies, PET or PET/CT was able to differentiate sporadic inclusion body myositis (IBM) from non-IBM myositis.

Conclusion

PET or PET/CT performs relatively well as a malignancy screening tool for people with IIM in comparison to standard screening methods. While false positives for malignancy on PET can lead to unnecessary invasive investigations, this also occurs with conventional screening. PET/CT also appears to be a beneficial tool for detecting ILD in those with IIM and may predict its severity. While PET/CT may detect skeletal muscle inflammation in IIM, its utility beyond the standard and readily available diagnostic tests for measuring muscle disease activity remains unclear. Early evidence indicates PET-amyloid may be able to subtype IBM from non-IBM myopathic disease, although more data are needed. More research is needed to evaluate whether PET could be used as a tool for detecting cardiac involvement in IIM, or if extending the PET scan field of view might increase the cancer detection yield and permit a more accurate assessment of extramuscular manifestations in IIM. PET/CT holds promise as a single tool that can simultaneously evaluate multiple aspects of IIM early in the diagnostic process. These include screening for associated malignancy in high-risk patients, stratifying higher risk ILD, and providing information on muscle inflammation.

Disclosure of Interests

None declared

AB0370 UTILITY OF CRP AND ESR IN THE DIAGNOSIS OF GIANT CELL ARTERITIS RELAPSE IN A PHASE 2 TRIAL OF MAVRILIMUMAB

Background:

No universally accepted definition of flare currently exists in giant cell arteritis (GCA). Although relapses are defined mostly on clinical grounds (recurrence of GCA-related signs/symptoms), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) help clinicians assess disease activity. In fact, >70% of patients on glucocorticoids (GCs) alone have increased CRP or ESR when the disease is active. In contrast, tocilizumab, given its IL-6-blockade effect in the liver, rapidly reduces CRP and ESR levels, rendering them unreliable for disease activity monitoring. Mavrilimumab – a GM-CSF receptor α inhibitor with demonstrated efficacy in a Phase 2 GCA trial1 – downregulates inflammation upstream of IL-6. We hypothesized that mavrilimumab would not interfere with the utility of CRP and ESR in monitoring disease activity and in identifying GCA relapse.

Objectives:

To analyze the relationship between CRP/ESR and clinical disease activity in GCA patients treated with mavrilimumab.

Methods:

New-onset and relapsing GCA patients with active disease were recruited. GC-induced remission (no GCA symptoms and CRP <1 mg/dL or ESR <20 mm/hr) was required by baseline. Patients were randomized 3:2 to mavrilimumab 150 mg or placebo subcutaneously every 2 weeks plus a protocol-defined 26-week prednisone taper. The primary efficacy endpoint was time to relapse by Week 26. Relapse (adjudicated) was defined as recurrent GCA-related signs/symptoms, including new/worsening vasculitis on imaging, concurrent with CRP ≥1 mg/dL and/or ESR ≥30 mm/hr. CRP and ESR were also measured periodically during the trial.

This post hoc analysis assessed the association of recurrent GCA-related signs/symptoms with concurrent CRP or ESR elevation post-randomization by treatment arm. We also assessed the proportion of patients with CRP or ESR elevation without GCA-related signs/symptoms up to Week 26.

Results:

Seventy patients were enrolled (mavrilimumab, N=42; placebo, N=28). The association of CRP or ESR elevation with unequivocal GCA-related signs/symptoms post-randomization was consistent regardless of treatment arm: 8/8 in the mavrilimumab group and 13/13 in the placebo group (Table 1). During relapse, median (range) CRP was 1.8 (1.4 – 8.4) mg/dL (mavrilimumab group) and 1.8 (1.1 – 9.0) mg/dL (placebo group). Corresponding ESR values were 39.5 (30 – 102) mm/hr (mavrilimumab group) and 49 (31 – 101) mm/hr (placebo group). Four mavrilimumab recipients had self-limited, equivocal GCA-related signs/symptoms without concurrent CRP or ESR elevation; all 4 completed the prespecified GC taper by Week 26 without need for rescue GCs, so relapse was not confirmed. At least 1 elevated CRP or ESR value in the absence of GCA-related signs/symptoms was observed in 58.8% of mavrilimumab recipients and 93.3% of placebo recipients by Week 26.

Conclusion:

The observed association of CRP or ESR elevation with GCA-related signs/symptoms is consistent with the upstream mechanism and supports the utility of the stringent protocol definition of relapse. The frequency and magnitude of CRP and ESR elevations at relapse were similar in both treatment groups, suggesting that CRP and ESR remain useful in assessments of disease activity in mavrilimumab-treated patients. CRP and ESR elevations without GCA-related signs/symptoms occurred more often in placebo recipients.

References:

[1]Cid, Unizony et al. Arthritis Rheumatol. 2020; 72 (suppl 10)

Table 1.

CRP and ESR levels in patients with or without GCA relapse

Assessment§MavrilimumabPlaceboMavrilimumabPlaceboN=42N=28N=42N=28With RelapseWithout Relapse# of patients8 (19.1)13 (46.4)34 (81.0)15 (53.6) Elevated CRP* or ESR†8 (100.0)13 (100.0)20 (58.8)14 (93.3)  Elevated CRP*7 (87.5)10 (76.9)10 (29.4)11 (73.3)   Median (range) mg/dL1.8 (1.4 - 8.4)1.8 (1.1 - 9.0)2.6 (1.3 – 7.0)2.0 (1.0 – 6.6) Elevated ESR†6 (75.0)9 (69.2)16 (47.1)10 (66.7)  Median (range) mm/hr39.5 (30 - 102)49.0 (31 - 101)41.5 (30 - 110)53.5 (30 - 82)

§# (%), except where indicated otherwise.

*CRP ≥ 1 mg/dL

†ESR ≥ 30 mm/hr

Disclosure of Interests:

Sebastian Unizony Consultant of: Janssen and Kiniksa, Grant/research support from: Genentech, Maria C. Cid Speakers bureau: Roche and Kiniksa, Paid instructor for: GSK and Vifor, Consultant of: Janssen, GSK, and Abbvie, Grant/research support from: Kiniksa, Elisabeth Brouwer Speakers bureau: Dr. E.Brouwer as an employee of the UMCG received speaker fees and consulting fees from Roche in 2017 2018 which were paid to the UMCG., Consultant of: Dr. E.Brouwer as an employee of the UMCG received speaker fees and consulting fees from Roche in 2017 2018 which were paid to the UMCG., Lorenzo Dagna Speakers bureau: Abbvie, Amgen, Biogen, BMS, Celltrion, Galapagos, Glaxo SmithKline, Novartis, Pfizer, Roche, Sanofi-Genzyme, SOBI, Consultant of: Abbvie, Amgen, Biogen, BMS, Celltrion, Galapagos, Glaxo SmithKline, Novartis, Pfizer, Roche, Sanofi-Genzyme, SOBI; clinical trial for Kiniksa, Grant/research support from: Abbvie, Amgen, BMS, Celltrion, Galapagos, Novartis, Pfizer, Roche, Sanofi-Genzyme, SOBI, Merk Sharp &Dohme, Janssen, Kiniksa, Bhaskar Dasgupta Paid instructor for: Educational grant symposium/workshop for Roche-chugai, Sanofi, and Abbvie, Consultant of: CI UK for the Kiniksa trial, Grant/research support from: Educational grant symposium/workshop for Roche-chugai, Sanofi, and Abbvie, Bernhard Hellmich Consultant of: Honoraria paid to the institution for participation in the clinical trial, Eamonn Molloy: None declared, Carlo Salvarani: None declared, Bruce C. Trapnell Consultant of: Consultant member of DSMB for Kiniksa., Kenneth J Warrington Consultant of: Clinical trial support from Eli Lilly and Kiniksa, Ian Wicks: None declared, Manoj Samant Shareholder of: Kiniksa Pharmaceuticals, Employee of: Kiniksa Pharmaceuticals, Teresa Zhou Shareholder of: Kiniksa Pharmaceuticals, Employee of: Kiniksa Pharmaceuticals, Lara Pupim Shareholder of: Kiniksa Pharmaceuticals, Employee of: Kiniksa Pharmaceuticals, John F. Paolini Shareholder of: Kiniksa Pharmaceuticals, Employee of: Kiniksa Pharmaceuticals

SAT0279 FACTORS PREDICTIVE OF POSITIVE TEMPORAL ARTERY BIOPSY IN TWO AUSTRALIAN COHORTS

Background:

Temporal artery biopsy (TAB) is widely recognised as the diagnostic gold standard for GCA despite having a poor sensitivity due to the presence of ‘skip’ lesions. There is, however, a lack of consensus guiding TAB practice, particularly in relation to optimal length, need for bilateral specimens, and number of segments examined.

Objectives:

To investigate the impact of factors such as total biopsied length, laterality, segment number, and referral centre on histopathological outcomes in an Australian setting.

Methods:

Reports for all available biopsy specimens labelled “temporal artery” were extracted from the pathology service records of two rheumatology referral centres with adjacent geographic catchments. Each histopathology report was manually reviewed to establish length of biopsied artery, laterality, and number of segments, along with patient demographics such as age, sex, and referral centre. Key histopathological findings including intimal hyperplasia, disruption of the internal elastic lamina, presence of giant cells, and adventitial inflammation were recorded. Multivariable logistic regression with site-varying intercept was performed.

Results:

TAB reports from a total of 577 patients were captured, with results available from the two centres from 1999-2019 and 2010-2019 respectively. The mean age in this group was 73, and 69% were female (Table 1). A bilateral TAB was performed in 29%, and the mean total biopsy length was 2.5cm. Of these patients, 122 had positive biopsies (21%), with intimal hyperplasia reported in 100 (17%), giant cells in 83 (14%), and adventitial findings in 68 (12%). Positive biopsy weakly correlated with increased total length of biopsy in centimetres (OR 1.25 [1.06-1.47]) (Figure 1) and increased age in years (OR 1.02 [1.00-1.05]) but not laterality or sex (Table 2). There was a substantial difference between the two centres, which was incompletely accounted for once corrected for total biopsy length and calendar year of biopsy, suggesting either unmeasured differences in patient demographics or a difference in clinical practice. This change was preserved across analysis of different histopathological subtypes.

Table 1.

Patient characteristics by biopsy result.

Negative(n = 455)Positive(n = 122)Total(n = 577)Age (years) Mean (SD)72 (± 11)75 (± 8.9)73 (± 10)Sex Female310 (68%)88 (72%)398 (69%) Male145 (32%)34 (28%)179 (31%)Maximum biopsy length (cm) Mean (SD)1.8 (± 0.86)2.0 (± 1.10)1.9 (± 0.92)Total biopsy length (cm) Mean (SD)2.4 (± 1.6)2.8 (± 2.1)2.5 (± 1.7)Mean biopsy length (cm) Mean (SD)1.7 (± 0.78)1.9 (± 0.97)1.7 (± 0.83)Laterality Bilateral130 (29%)39 (32%)169 (29%) Unilateral325 (71%)83 (68%)408 (71%)Table 2.

Associations with positive TAB on multivariable logistic regression.

Overall positive findingIntimal hyperplasiaGiant cellsAdventitial inflammationTotal biopsy length (cm)1.25(1.06-1.47)1.18(0.98-1.40)1.21(1.00-1.46)1.07(0.87-1.31)Unilateral (vs. bilateral)1.56(0.82-3.07)1.12(0.56-2.30)1.28(0.61-2.77)0.82(0.38-1.82)Age (years)1.02(1.00-1.05)1.02(1.00-1.04)1.03(1.00-1.05)1.00(0.98-1.03)Male (vs. female)0.83(0.52-1.29)0.63(0.37-1.05)0.59(0.32-0.92)0.75(0.41-1.31)Centre 2 (vs. centre 1)0.54(0.34-0.84)0.41(0.24-0.68)0.55(0.32-0.92)0.46(0.25-0.82)Figure 1.

The effect of total biopsy length on result, stratified by laterality.

Conclusion:

Total biopsy length was weakly associated with a positive TAB result, but differences in results between referral centres independent of biopsy length suggest other selection factors may be important in determining TAB yield. Examination of differences in results between a greater number of referral centres would assist in determining the extent of this variability.

Disclosure of Interests:

None declared

Differential regulation of the serotonin 1 A transcriptional modulators five prime repressor element under dual repression-1 and nuclear-deformed epidermal autoregulatory factor by chronic stress

Chronic stress is known to affect brain areas involved in learning and emotional responses. These changes, thought to be related to the development of cognitive deficits are evident in major depressive disorder and other stress-related pathophysiologies. The serotonin-related transcription factors (Freud-1/CC2D1A; five prime repressor element under dual repression/coiled-coil C2 domain 1a, and NUDR/Deaf-1; nuclear-deformed epidermal autoregulatory factor) are two important regulators of the 5-HT1A receptor. Using Western blotting and quantitative real-time polymerase chain reaction (qPCR) we examined the expression of mRNA and proteins for Freud-1, NUDR, and the 5-HT1A receptor in the prefrontal cortex (PFC) of male rats exposed to chronic restraint stress (CRS; 6 h/day for 21 days). After 21 days of CRS, significant reductions in both Freud-1 mRNA and protein were observed in the PFC (36.8% and 32%, respectively; P<0.001), while the levels of both NUDR protein and mRNA did not change significantly. Consistent with reduced Freud-1 protein, 5-HT1A receptor mRNA levels were equally upregulated in the PFC, while protein levels actually declined, suggesting post-transcriptional receptor downregulation. The data suggest that CRS produces distinct alterations in the serotonin system specifically altering Freud-1 and the 5-HT1A receptor in the PFC of the male rat while having no effect on NUDR. These results point to the importance of understanding the mechanism for the differential regulation of Freud-1 and NUDR in the PFC as a basis for understanding the related effects of chronic stress on the serotonin system (serotonin-related transcription factors) and stress-related disorders like depression.

SAPHO: rare or just not recognized?

OBJECTIVE

The SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome describes an association between musculoskeletal disorders, in particular hyperostosis involving the bones and joints of the anterior chest wall, and various dermatologic conditions. It has been reported in Europe and Japan, but no Australian series have been published. We describe the clinical, laboratory, and radiographic features of a group of patients with the SAPHO syndrome and compare this with the literature.

METHODS

We performed a retrospective review of patients seen in our department between 1990 and 1998 who met the proposed diagnostic criteria for SAPHO. Information regarding age, sex, disease duration, skeletal site(s) of disease, presence of skin disease, previous treatment, and response to treatment was collected. Laboratory tests were reviewed, as was all available radiology and bone scintigraphy.

RESULTS

Six women with a mean age of 40 years fulfilled the criteria for SAPHO. The skeletal manifestations were similar to those reported in the literature, with hyperostosis of the anterior chest wall being the central feature. Cervical spine and pubic bone were other sites of involvement, whereas sacroiliitis and peripheral joint synovitis were not seen. Skin disease was less frequent in our population than has been reported in other series. Nonsteroidal anti-inflammatory drugs were frequently prescribed as first-line treatment but had limited efficacy. Intravenous pamidronate was administered to two patients, resulting in complete resolution of pain in one patient and 50% reduction in pain in the other.

CONCLUSIONS

The SAPHO syndrome may be underrecognized as the skin manifestations in our patients were mild or absent. Although optimal treatment for these patients remains unclear, it is important to make the diagnosis of SAPHO to avoid unnecessary investigations and treatment.

Ankylosing spondylitis antirheumatic drug trials: Effects of a standardized instructional viddeotape on the reliability of observer-dependent outcome measures

AIMS

A study was designed to assess the effects of a standardized instruction videotape on reducing interobserver variability for several commonly used observer-dependent outcome measures.

METHODS

During a single day, six rheumatologists independently examined six patients with ankylosing spondylitis (AS) in a predetermined order using a Latin square design, before and after viewing a standardized videotape demonstrating 14 examination techniques. Reliability coefficients were calculated based on the variance components of the analysis of variance (ANOVA) table.

RESULTS

Prestandardization reliability coefficients were <0.80 for three measures. Following standardization 12 reliability coefficients exceeded 0.80. For the majority of measures prestandardization reliability coefficients were high and no further improvement in reliability could be demonstrated. For one measure of cervical extension, but not another, an important and beneficial effect in reliability was noted. It was not possible to achieve adequate reliability in the performance of the chest excursion measurement.

CONCLUSIONS

It is usually assumed that serial measurement in clinical trials should be performed by the same assessor because of concern regarding interobserver variability. However, the high levels of prestandardization interobserver reliability observed in this study indicate that for these variables serial measurements in a clinical trial could be made by different assessors, assuming they were equally skilled. This observation has important implications for outcome measurement in AS clinical trials. Although high levels of prestandardization reliability precluded the demonstration of any significant effect, we speculate that the videotape might be effective in training less experienced assessors. Nevertheless, an alternative approach to standardization may be required for the chest excursion measurement. Reductions in observer variability have the potential to diminish sample size requirements for AS antirheumatic drug studies. The use of a videotape to achieve this goal offers cost and convenience advantages over one-on-one training procedures, and this method should be further assessed in a group of less experienced assessors.

Prevention of splenic granuloma formation in adjuvant arthritis by 2-acetyl-4-tetrahydroxybutylimidazole (THI)

Adjuvant-induced arthritis (AA) in Lewis rats is a widely used model of chronic inflammatory arthritis. Non-articular features such as weight loss and necrotizing granulomas of the spleen and lymph nodes also occur in this model. The compound 2-acetyl-4-tetrahydroxybutylimidazole (THI) marginally delayed the development of AA. However, this agent had no effect on the incidence or severity of disease. In contrast, THI totally prevented granuloma formation in the spleen and associated splenomegaly. We conclude that THI may be a useful adjunctive agent for some inflammatory diseases.

Use of monoclonal antibodies to detect disease associated HLA-DRB1 alleles and the shared epitope in rheumatoid arthritis

OBJECTIVE

To use a panel of monoclonal antibodies (Mab) which recognise HLA class II alleles associated with rheumatoid arthritis for fluorescence activated cell sorter (FACS) analysis of peripheral blood mononuclear cells (PBMNC) from patients with early and established rheumatoid arthritis and to compare these results against DNA oligotyping of HLA class II molecules in the same patients.

METHODS

27 patients (18 from an early arthritis clinic, nine with established rheumatoid arthritis) were studied using both techniques. PBMNC were stained with Mab which recognise the shared epitope, the HLA-DRB1*04 molecule and its* 0401, *0404 subtypes in the presence of bound peptide. Mab stained cells were analysed by FACS. Genomic DNA was prepared from PBMNC and use for DNA oligotyping and sequencing by standard methods.

RESULTS

FACS analysis of Mab stained PBMNC gave identical results to those obtained by DNA oligotyping in 26/27 patients. The antibodies identified the shared epitope in 14/14 cases and the presence of an HLA-DRB1*04 molecule in 12/12 cases. HLA-DRB1*0404 was identified in 4/4 cases. HLA-DRB1*0401 was identified in 5/6 cases. One patient oligotyped as HLA-DRB1*0401, but consistently failed to react with the *0401 Mab. DNA sequencing of the second exon of the HLA-DRB1*0401 allele in this patient confirmed a normal HLA-DRB1*0401 genotype.

CONCLUSIONS

FACS analysis of PBMNC stained with Mab recognising the shared epitope and rheumatoid arthritis associated HLA susceptibility molecules provides a rapid, reliable, and more accessible alternative to DNA oligotyping. The apparent discordance between phenotypic and genetic analysis of HLA-DRB1*0401 in one patient, may reflect variability in HLA-DRB1*0401 gene expression or in class II peptide presentation.

New perspectives on rheumatoid arthritis

Rheumatoid arthritis (RA) remains one of the most common, puzzling and poorly treated diseases of humans. However, a surge of interest in the biology of chronic inflammation and in the design of more-potent and specific inhibitors of pro-inflammatory pathways heralds an optimistic era for the treatment of RA. A recent symposium provided a multidisciplinary perspective on the current status of such studies.

The metabolism of C3 and C4 in patients with immune complexes and normal complement levels

The metabolism of the complement proteins, C3 and C4 was examined in two groups of patients with a high incidence of detectable immune complexes but normal levels of complement components. The specific aim was to ascertain whether significant ongoing complement activation occurred in these patients. Eleven patients with rheumatoid arthritis (RA), 11 with infection and 11 control subjects were studied. Each received approximately 10 microCi 125l.C4 and 2.5 microCi 131l.C3 by intravenous injection. Analysis of turnover data showed that there was significant hypercatabolism of both C3 and C4 in the two study groups compared to controls. Plasma production of C4 was normal for both groups (despite the presence of C4 null alleles in six out of 11 of the RA group), while C3 production was significantly elevated in both RA and infection (p less than 0.01 and p less than 0.001 respectively). Patients with infection showed a significant increase in extravascular/intravascular distribution of both proteins. The data show that immune complex formation is associated with accelerated turnover of complement proteins, irrespective of co-existing tissue damage or changes in the serum concentration of complement components. The findings suggest that both activation of complement and maintenance or enhancement of protein synthesis are important for the efficient processing of immune complexes in vivo.

General practitioners in the Western Metropolitan Health Region of Sydney

A comprehensive survey of the number of general practitioners in the Western Metropolitan Health Region of Sydney identified 753 general practitioners with one or more practice locations in the region; this was the equivalent of 711 full-time general practitioners, and represented a general practitioner-population ratio of 1:1533.