IL-1β, IL-6, and TNF gene polymorphisms do not affect the treatment outcome of rheumatoid arthritis...
Transcript of IL-1β, IL-6, and TNF gene polymorphisms do not affect the treatment outcome of rheumatoid arthritis...
IL-1�, IL-6, and TNF gene polymorphisms do not
affect the treatment outcome of rheumatoid
arthritis patients with leflunomide
Andrzej Pawlik1, Magdalena Herczyñska2, Mateusz Kurzawski1, Krzysztof
Safranow3, Violetta Dziedziejko3, Zygmunt Juzyszyn1, Marek DroŸdzik1
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Abstract:
Leflunomide is an isoxazole derivative that is structurally and functionally unrelated to other known immunomodulatory drugs. Pre-
vious studies have revealed that therapy with leflunomide causes decreased production of mediators such as IL-1�, IL-6, and TNF-�,
which are involved in inflammatory process. The aim of the present study was to examine whether the polymorphisms in genes
IL1B, IL6, and TNF may affect treatment outcomes in RA patients treated with leflunomide.
The study was carried out on 129 patients (106 women, 23 men, mean age 52.9 ± 11.03) diagnosed with RA and treated with leflu-
nomide 20 mg daily. Clinical improvement was evaluated according to the American College of Rheumatology (ACR) 20% and
50% response criteria.
There were no statistically significant associations between the studied genotypes and improvement of disease activity parameters.
The results of the present study suggest that IL1�, IL6, and TNF gene polymorphisms are not significant factors influencing the ther-
apy outcome of RA patients with leflunomide.
Key words:
rheumatoid arthritis, leflunomide, cytokines, polymorphism
Introduction
Rheumatoid arthritis (RA) is a common autoimmune
disease in which a combination of risk alleles from
different susceptibility genes predisposes the patient
to development of clinical symptoms following expo-
sure to as yet unknown environmental factors. Treat-
ment of this disease is mainly based on drugs which
modulate its course, and previous studies have shown
that genetic factors influence the response to drugs
used in RA therapy [21]. Pharmacogenetics focuses
on the genetic variations responsible for drug metabo-
lism, drug transport, and drug targets to determine
how these variations result in inherited alterations in
medication outcomes [11, 14]. Identification of ge-
netic determinants of drug efficacy and toxicity will
be valuable because they can be ascertained in the in-
dividual patient before initiation of therapy [1, 12].
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Leflunomide is an isoxazole derivative that is
structurally and functionally unrelated to other known
immunomodulatory drugs. [2] In the intestinal mu-
cosa and in plasma, almost 100% of the compound is
nonenzymatically converted into the active open ring
malononitrile metabolite A77 1726. The main mo-
lecular target of A77 1726 is dihydroorotate dehydro-
genase (DHODH), a key enzyme of the novo py-
rimidine synthesis [5]. Consequently, the main effect
of leflunomide in immunomediated diseases has been
attributed to the inhibition of proliferation of B and T
cells. When activation occurs, these cells may expand
their pyrimidine biosynthesis [7, 10]. It is still not
clear which of these modes of action are relevant to
the immunosuppressive effect of leflunomide ob-
served in various autoimmune mediated diseases. Pre-
vious studies have revealed that therapy with leflu-
nomide causes the decreased production of mediators
such as IL-1�, IL-6, and TNF-�, which are involved
in the inflammatory process [6, 16]. The synthesis of
these mediators is genetically determined, and previ-
ous studies have indicated that polymorphisms in cy-
tokine genes may influence treatment outcome with
antirheumatic drugs. The aim of the present study was
to examine whether the polymorphisms in genes en-
coding IL-1�, IL-6, and TNF-� may affect the treat-
ment outcome in RA patients treated with leflu-
nomide.
Material and Methods
Patients
The study was carried out on 129 patients (106
women, 23 men, mean age 52.9 ± 11.3) diagnosed
with rheumatoid arthritis, treated with leflunomide
20 mg daily. Rheumatoid arthritis was diagnosed ac-
cording to the criteria of American College of Rheu-
matology (ACR). All patients underwent a monthly
evaluation for one year, applying the 1995 ACR pre-
liminary definition of improvement in rheumatoid ar-
thritis. Clinical improvement was evaluated according
to the American College of Rheumatology (ACR)
20% and 50% response criteria. The ACR core set of
variables included: the number of swollen joints, the
number of tender joints, patient assessment of pain on
a 100-mm visual analog scale (VAS), erythrocyte
sedimentation rate, C-reactive protein, and disease ac-
tivity score (DAS28). A 28-joint count (including the
metacarpophalangeal joints, the proximal interphalan-
geal joints, wrists, and elbows) was also used [8, 9,
22, 27]. The study was approved by the local ethics
committee and written informed consent was obtained
from all subjects.
Genotyping
The polymorphisms of IL1� (rs1143634:C>T silent
polymorphism in exon 5), IL6 (rs1800795:C>G in
promoter region), and TNF (rs1800629:G>A in gene
promoter) were determined by means of PCR-RFLP
methods, as previously described [13].
Statistical analysis
Allele and genotype frequencies were compared using
the two-sided Fisher exact test. Odds ratios (OR) and
their 95% confidence intervals (95% CI) were calcu-
lated for the chance of response to treatment using
a multivariate logistic regression model with three
analyzed polymorphisms as independent variables.
A p-level of less than 0.05 was considered statistically
significant. Calculations were performed using the
Statistica 6.1 software package.
Results
The baseline disease activity parameters of RA pa-
tients enrolled in the study are presented in Table 1.
Tables 2–7 present the percentage of patients that
reached clinical improvement after 6 and 12 months
of therapy according to particular parameters as de-
fined by the American College of Rheumatology
(ACR) 20% and 50% response criteria.
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Parameter Value
Blood sedimentation rate 53.73 ± 26.53
Swollen joints 8.3 ± 3.37
Tender joints 10.05 ± 3.7
VAS 7.87 ± 1.38
DAS28 5.33 ± 0.62
CRP [mg/dl] 41.93 ± 38.26
As shown in Tables 2–7, there were no statistically
significant differences in percentage of patients that
reached the 20% and 50% improvement in ESR, CRP,
DAS28, and VAS values, as well as the number of
swollen and tender joints after 6 and 12 months of
treatment in correlation with IL-1� and TNF-� geno-
types. Similarly, there were no statistically significant
differences in percentage of patients that reached the
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Parameter IL1� + 3953 genotypes Statisticalsignificance p*TC + CC vs. TTTT
(N = 85)TC + CC
(N = 41 + 3)
After 6 months of therapy
ESR (26.25%) (26.19%) 1.000
Swollen joints (66.67%) (66.67%) 1.000
Tender joints (50.62%) (52.38%) 1.000
VAS (33.33%) (45.00%) 0.234
DAS28 (3.90%) (2.38%) 1.000
CRP (56.58%) (55.26%) 1.000
After 12 months of therapy
ESR (25.35%) (42.86%) 0.077
Swollen joints (92.75%) (97.14%) 0.661
Tender joints (84.06%) (88.57%) 0.768
VAS (78.26%) (80.00%) 1.000
DAS28 (19.12%) (14.29%) 0.596
CRP (63.24%) (70.59%) 0.513
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Parameter IL1 � + 3953 genotype Statisticalsignificance p*TC + CC vs. TTTT
(N = 85)TC + CC
(N = 41 + 3)
After 6 months of therapy
ESR (55.00%) (61.90%) 0.563
Swollen joints (95.06%) (95.24%) 1.00
Tender joints (93.83%) (90.48%) 0.489
VAS (88.89%) (87.50%) 1.00
DAS28 (50.65%) (47.62%) 0.848
CRP (73.68%) (81.58%) 0.483
After 12 months of therapy
ESR (59.15%) (65.71%) 0.534
Swollen joints (97.10%) (97.14%) 1.00
Tender joints (95.65%) (94.29%) 1.00
VAS (89.86%) (97.14%) 0.261
DAS28 (77.94%) (91.43%) 0.105
CRP (80.88%) (85.29%) 0.783
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Parameter IL-6 -174 G > C genotypes Statistical significance p*GG vs.
(GC + CC)GG (N = 38) GC (N = 63) CC (N = 28)
After 6 months of therapy
ESR (54.29%) (56.67%) (62.96%) 0.689
Swollen joints (94.44%) (93.33%) (100%) 1.000
Tender joints (94.44%) (90%) (96.3%) 1.000
VAS (77.14%) (89.83%) (100%) 0.024
DAS28 (51.43%) (47.46%) (52%) 0.842
CRP (75%) (70.91%) (88.89%) 0.811
After 12 months of therapy
ESR (53.33%) (69.09%) (52.38%) 0.376
Swollen joints (96.67%) (96.23%) (100%) 1.000
Tender joints (93.33%) (94.34%) (100%) 0.624
VAS (96.67%) (90.57%) (90.48%) 0.433
DAS28 (86.67%) (82.69%) (76.19%) 0.577
CRP (90%) (82.35%) (71.43%) 0.259
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Parameter IL-6 -174 G > C genotypes Statistical significance p*GG vs. (GC + CC)
GG (N = 38) GC (N = 63) CC (N = 28)
After 6 months of therapy
ESR (22.86%) (28.33%) (25.93%) 0.655
Swollen joints (50%) (70%) (81.48%) 0.019
Tender joints (41.67%) (51.67%) (62.96%) 0.234
VAS (34.29%) (30.51%) (55.56%) 0.835
DAS28 (2.86%) (3.39%) (4%) 1.000
CRP (56.25%) (52.73%) (62.96%) 1.000
After 12 months of therapy
ESR (23.33%) (36.36%) (28.57%) 0.354
Swollen joints (93.33%) (92.45%) (100%) 1.000
Tender joints (90%) (84.91%) (80.95%) 0.545
VAS (76.67%) (81.13%) (76.19%) 0.792
DAS28 (10%) (19.23%) (23.81%) 0.260
CRP (70%) (62.75%) (66.67%) 0.650
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Parameter TNF� -209 genotypes Statisticalsignificance p*GA + AA vs. GGGG
(N = 87)GA + AA
(N = 39 + 3)
After 6 months of therapy
ESR (56.79%) (58.54%) 1.000
Swollen joints (97.56%) (90.24%) 0.094
Tender joints (93.90%) (90.24%) 0.479
VAS (90.12%) (85.00%) 0.546
DAS28 (51.90%) (45.00%) 0.561
CRP (74.03%) (81.08%) 0.485
After 12 months of therapy
ESR (62.86%) (58.33%) 0.678
swollen joints (98.55%) (94.29%) 0.261
Tender joints (95.65%) (94.29%) 1.000
VAS (92.75%) (91.43%) 1.000
DAS28 (88.41%) (70.59%) 0.050
CRP (85.51%) (75.76%) 0.270
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Parameter TNF�-209 genotypes Statisticalsignificance p*GA + AA vs. GGGG
(N = 87)GA + AA
(N = 39 + 3)
After 6 months of therapy
ESR (28.40%) (21.95%) 0.517
Swollen joints (69.51%) (60.98%) 0.417
Tender joints (52.44%) (48.78%) 0.707
VAS (38.27%) (35.00%) 0.842
DAS28 (5.06%) (0.00%) 0.299
CRP (57.14%) (54.05%) 0.840
After 12 months of therapy
ESR (30.00%) (33.33%) 0.825
Swollen joints (95.65%) (91.43%) 0.401
Tender joints (88.41%) (80.00%) 0.254
VAS (78.26%) (80.00%) 1.00
DAS28 (14.49%) (23.53%) 0.278
CRP (66.67%) (63.64%) 0.825
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20% and 50% improvement in ESR, CRP, and DAS28
values as well as the number of swollen and tender
joints after 6 and 12 months of treatment in associa-
tion with IL-6 genotypes. In contrast, the percentage
of subjects with 20% improvement in VAS values af-
ter 6 months of the therapy was significantly in-
creased in patients with IL-6 rs1800795 GC + CC
genotype. However, this association was not observed
after 12 months of the therapy.
When the multivariate logistic regression model
was used to study the influence of three polymor-
phisms on each parameter of clinical improvement,
significant associations (p < 0.05) were observed only
for three parameters. The IL-6 GC + CC genotypes
were associated with a higher rate of 50% improve-
ment in swollen joints (OR = 2.73, 95% CI = 1.20–6.21,
p = 0.015) and 20% improvement in VAS values
(OR = 3.88, 95%CI = 1.21–12.37, p = 0.021) after
6 months of therapy. The TNF-� GA + GG genotypes
were associated with lower (OR = 0.24, 95% CI =
0.08–0.73, p = 0.011) and IL-1� TC + CC with higher
(OR = 4.19, 95% CI = 1.03–17.01, p = 0.043) rates of
20% improvement in DAS28 after 12 months of therapy.
During therapy, an increase of erythrocytes and he-
moglobin was observed. There was also an increase
of alanine aminotransferase activity, but the values re-
mained within the range of normal values. The
number of thrombocytes was decreased, and the cre-
atinine concentrations remained unchanged. There
were no statistically significant correlations between
studied genotypes and changes in alanine aminotrans-
ferase activity, creatinine and hemoglobin concentra-
tions, and number of erythrocytes and thrombocytes
(data not shown).
Discussion
According to our knowledge, this is the first study ex-
amining the association between IL1-�, IL-6, and
TNF gene polymorphisms and leflunomide treatment
outcome in RA patients. The efficacy of the therapy
was satisfactory. About 60% of patients reached 20%
improvement in ESR values after 12 months of treat-
ment. More than 90% of patients reached the 20% im-
provement level in number of swollen and tender
joints and VAS values after a 12-month course of
treatment. A 20% improvement of DAS values was
noted in about 80% of patients. Generally, there were
no significant associations between clinical improve-
ment and studied genotypes. Only the improvement in
VAS values and swollen joints after 6 months of ther-
apy correlated significantly with IL-6 genotypes.
Moreover, the improvement in DAS28 correlated
with IL-1� and TNF� polymorphisms.
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IL-1� + 3953genotypes
TNF� –209genotypes
IL-6 -174 genotypes Total for all IL-6genotypes
GG GC CC
TT GG 16 33 12 61
TT GA 7 11 5 23
TT AA 0 0 1 1
Total for IL-1� TT genotype 23 44 18 85
TC GG 8 10 6 24
TC GA 6 8 2 16
TC AA 1 0 0 1
Total for IL-1� TC genotype 15 18 8 41
CC GG 0 0 2 2
CC GA 0 0 0 0
CC AA 0 1 0 1
Total for IL-1� CC genotype 0 1 2 3
Total for all IL-1� and TNF� genotypes 38 63 28 129
The clinical efficacy and safety of leflunomide has
been assessed in several clinical trials. In placebo-
controlled studies, clinical improvement as defined by
the American College of Rheumatology (ACR) 20%
response criteria [24] was statistically significant for
leflunomide (20 mg/day) as compared with placebo.
Leflunomide showed ACR 20% response rates com-
parable with those of sulfasalazine (2 g/day) and
methotrexate (7.5–15 mg/week), and significant im-
provement in health-related quality of life and func-
tional ability compared with sulfasalazine and
methotrexate in the placebo-controlled clinical trials
[23]. The most common adverse events associated
with leflunomide treatment were gastrointestinal, con-
sisting primarily of diarrhea, increased aminotransfe-
rase activity, abdominal pain, and nausea/vomiting
[18, 20, 23–25]. In our study, leflunomide was gener-
ally well tolerated, the adverse events in the majority
were mild and often transient. There was no signifi-
cant association between adverse events and studied
genotypes. Previous studies indicated the effect of le-
flunomide on production of proinflammatory cytoki-
nes. Litinsky et al. studied the effect of leflunomide
on serum levels of MMP-1, MMP-3, IL-10, and IL-6
in patients with refractory RA and observed a signifi-
cant decrease of these parameters after therapy [16].
The authors of another study examined the effect of
leflunomide on IL-1�, TNF-�, MMP3, and nitric ox-
ide by activated human synovial tissue [6]. These
authors revealed that leflunomide inhibits the produc-
tion of IL-1�, TNF-�, MMP3, and nitric oxide by ac-
tivated human synovial tissue. The results of Li et al.
suggest also that the antiinflammatory mechanisms of le-
flunomide might be related to the inhibitory level of IL-1,
IL-6, and TNF-� from macrophages [15]. Manna et al.
showed that leflunomide also blocks NF-�B reporter
gene expression induced by TNFR1, TNFR-associated
factor 2, and NF-�B-inducing kinase (NIK), but not
strongly activated by the p65 subunit of NF-�B, suggest-
ing that leflunomide acts downstream of NIK [17]. The
authors of another study examined the immunoregulatory
action of leflunomide in the cytokine network involved in
RA pathogenesis [26]. They observed an increase in IL-
10 secretion, and a decrease in IL-11 as well as decreased
IL-6 and prostaglandin E2 synthesis.
Moreover, the results of Burger et al. and Migita et
al. confirmed that the antiinflammatory properties of
leflunomide are associated with decreased production
of proinflammatory mediators [3, 19]. In our study,
the outcome of therapy with leflunomide was associ-
ated with the improvement of disease activity parame-
ters; nevertheless, there was no significant association
with the studied polymorphisms of cytokine genes.
The results of the present study suggest that IL1�,
IL6, and TNF gene polymorphisms are not the signifi-
cant factors influencing the therapy outcome of RA
patients with leflunomide.
References:
1. Bartnicka L, Kurzawski M, DroŸdzik A, P³oñska-
Goœciniak E, Górnik W, DroŸdzik M: Effect of ABCB1
(MDR1) 3435C >T and 2677G >A,T polymorphisms and
P-glycoprotein inhibitors on salivary digoxin secretion in
congestive heart failure patients. Pharmacol Rep, 2007,
59, 323–329.
2. Brazelton TR, Morris RE: Molecular mechanisms of action
of new xenobiotic immunosuppressive drugs: tacrolimus
(FK506), sirolimus (rapamycin), mycophenolate mofetil
and leflunomide. Curr Opin Immunol, 1996, 8, 710–720.
3. Burger D, Begué-Pastor N, Benavent S, Gruaz L, Kauf-
mann MT, Chicheportiche R, Dayer JM: The active me-
tabolite of leflunomide, A77 1726, inhibits the produc-
tion of prostaglandin E(2), matrix metalloproteinase 1
and interleukin 6 in human fibroblast-like synoviocytes.
Rheumatology, 2003, 42, 89–96.
4. Chrzanowska M, Kurzawski M, DroŸdzik M, Mazik M,
Oko A, Czekalski S: Thiopurine S-methyltransferase
phenotype-genotype correlation in hemodialyzed patients.
Pharmacol Rep, 2006, 58, 973–978.
5. Davis JP, Cain GA, Pitts WJ, Magolda RL, Copeland
RA: The immunosuppressive metabolite of leflunomide
is a potent inhibitor of human dihydroorotate dehydroge-
nase. Biochemistry, 1996, 35, 1270–1273.
6. Elkayam O, Yaron I, Shirazi I, Judovitch R, Caspi D, Ya-
ron M: Active leflunomide metabolite inhibits inter-
leukin 1�, tumour necrosis factor �, nitric oxide, and
metalloproteinase-3 production in activated human syno-
vial tissue cultures. Ann Rheum Dis, 2003, 62, 440–443.
7. Fairbanks LD, Jacomelli G, Micheli V, Slade T, Sim-
monds HA: Severe pyridine nucleotide depletion in fi-
broblasts from Lesch-Nyhan patients. Biochem J, 2002,
366, 265–272.
8. Felson DT, Anderson JJ, Boers M: American College of
Rheumatology. Preliminary definition of improvement in
rheumatoid arthritis. Arthritis Rheum, 1995, 38, 727–735.
9. Felson DT, Anderson JJ, Boers M: The American Col-
lege of Rheumatology preliminary core set of disease ac-
tivity measures for rheumatoid arthritis clinical trials.
The Committee on Outcome Measures in Rheumatoid
Arthritis Clinical Trials. Arthritis Rheum, 1993, 36, 729–740.
10. Herrmann ML, Schleyerbach R, Kirschbaum BJ: Leflu-
nomide: an immunomodulatory drug for the treatment of
rheumatoid arthritis and other autoimmune diseases. Im-
munopharmacology, 2000, 47, 273–289.
286 ������������� �� ����� ����� ��� ������
11. Kotrych K, Sulikowski T, Domañski L, Bia³ecka M,
DroŸdzik M: Polymorphism in the P-glycoprotein drug
transporter MDR1 gene in renal transplant patients
treated with cyclosporin A in a Polish population. Phar-
macol Rep, 2007, 59, 199–205.
12. Kurzawski M, Bartnicka L, Florczak M, Górnik W,
DroŸdzik M: Impact of ABCB1 (MDR1) gene polymor-
phism and P-glycoprotein inhibitors on digoxin serum
concentration in congestive heart failure patients. Phar-
macol Rep, 2007, 59, 107–11.
13. Kurzawski M, Pawlik A, Czerny B, Domanski L, Rozan-
ski J, Drozdzik M: Frequencies of the common promoter
polymorphisms in cytokine genes in a Polish population.
Int J Immunogenet, 2005, 32, 285–291.
14. Kurzawski M, Pawlik A, Górnik W, DroŸdzik M: Fre-
quency of common MDR1 gene variants in a Polish
population. Pharmacol Rep, 2006, 58, 35–40.
15. Li WD, Ran GX, Teng HL, Lin ZB: Dynamic effects of
leflunomide on IL-1, IL-6, and TNF-alpha activity pro-
duced from peritoneal macrophages in adjuvant arthritis
rats. Acta Pharmacol Sin, 2002, 23, 752–756.
16. Litinsky I, Paran D, Levartovsky D, Wigler I, Kaufman
I, Yaron I, Yaron M et al.: The effects of leflunomide on
clinical parameters and serum levels of IL-6, IL-10,
MMP-1 and MMP-3 in patients with resistant rheuma-
toid arthritis. Cytokine, 2006, 33, 106–110.
17. Manna SK, Aggarwal BB: Immunosuppressive leflu-
nomide metabolite (A77 1726) blocks TNF-dependent
nuclear factor-�B activation and gene expression. J Im-
munol, 1999, 162, 2095–2102.
18. Martin K, Bentaberry F, Dumoulin C, Dehais J, Haram-
buru F, Bégaud B, Schaeverbeke T: Effectiveness and
safety profile of leflunomide in rheumatoid arthritis: ac-
tual practice compared with clinical trials. Clin Exp
Rheumatol, 2005, 23, 80–84.
19. Migita K, Miyashita T, Ishibashi H, Maeda Y, Nakamura
M, Yatsuhashi H, Ida H et al.: Suppressive effect of le-
flunomide metabolite (A77 1726) on metalloproteinase
production in IL-1� stimulated rheumatoid synovial fi-
broblasts. Clin Exp Immunol, 2004, 137, 612–616.
20. Mladenovic V, Domljan Z, Rozman B, Jajic I, Mi-
hajlovic D, Dordevic J, Popovic M et al.: Safety and ef-
fectiveness of leflunomide in the treatment of patients
with active rheumatoid arthritis. Results of a random-
ized, placebo-controlled, phase II study. Arthritis Rheum,
1995, 38, 1595–1603.
21. Pawlik A, Kurzawski M, Górnik W, D¹browska-¯amo-
jcin E, DroŸdzik M: 677C > T and 1298A > C MTHFR
polymorphisms affect arechin treatment outcome in
rheumatoid arthritis. Pharmacol Rep, 2007, 59, 721–726.
22. Pincus T, Summey JA, Soraci SA Jr, Wallston KA, Hum-
mon NP: Assessment of patient satisfaction in activities of
daily living using a modified Stanford Health Assessment
Questionnaire. Arthritis Rheum, 1983, 26, 1346–1353.
23. Smolen JS, Kalden JR, Scott DL, Rozman B, Kvien TK,
Larsen A, Loew-Friedrich I et al.: Efficacy and safety of
leflunomide compared with placebo and sulphasalazine
in active rheumatoid arthritis: a double-blind, random-
ised, multicentre trial. European Leflunomide Study
Group. Lancet 1999, 353, 259–266.
24. Strand V, Cohen S, Schiff M, Weaver A, Fleischmann R,
Cannon G, Fox R et al: Treatment of active rheumatoid
arthritis with leflunomide compared with placebo and
methotrexate. Leflunomide Rheumatoid Arthritis Investi-
gators Group. Arch Intern Med, 1999, 159, 2542–2550.
25. Van Roon EN, Jansen TL, Mourad L, Houtman PM,
Bruyn GA, Griep EN, Wilffert B et al.: Leflunomide in
active rheumatoid arthritis: a prospective study in daily
practice. Br J Clin Pharmacol, 2004, 57, 790–797.
26. Vergne-Salle P, Léger DY, Bertin P, Trèves R, Beneytout
JL, Liagre B: Effects of the active metabolite of le-
flunomide, A77 1726, on cytokine release and the
MAPK signalling pathway in human rheumatoid arthritis
synoviocytes. Cytokine, 2005, 31, 335–348.
27. Wolfe F, O’Dell JR, Kavanaugh A, Wilske K, Pincus T:
Evaluating severity and status in rheumatoid arthritis.
J Rheumatol, 2001, 28, 1453–1462.
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