Inefficacy of infliximab in primary Sjögren's syndrome: Results of the randomized, controlled trial of remicade in primary Sjögren's syndrome (TRIPSS)

Authors


Abstract

Objective

There is no effective treatment for patients with primary Sjögren's syndrome (SS). Since tumor necrosis factor α (TNFα) could be a key element in the pathogenesis of primary SS, we conducted a multicenter, randomized, double-blind, placebo-controlled trial to evaluate the effect of infliximab in primary SS.

Methods

A total of 103 patients with primary SS were randomly assigned to receive infliximab infusions (5 mg/kg) or placebo at weeks 0, 2, and 6 and were followed up for 22 weeks. All patients fulfilled the new American-European Consensus Group criteria for SS and had active disease as assessed by values >50 mm on 2 of 3 visual analog scales (VAS) (0–100 mm) that evaluated joint pain, fatigue, and buccal, ocular, skin, vaginal, or bronchial dryness. A favorable overall response was defined as the patient having ≥30% improvement between weeks 0 and 10 in the values on 2 of the 3 VAS. Secondary end points were values on each VAS separately, the number of tender and swollen joints, the basal salivary flow rate, results of the Schirmer test for lacrimal gland function, the focus score on labial salivary gland biopsy, the level of C-reactive protein, and the erythrocyte sedimentation rate evaluated at weeks 0, 10, and 22, as well as quality of life evaluated by use of the generic Short Form 36 questionnaire administered at weeks 0, 10, and 22.

Results

At week 10, 26.5% of patients receiving placebo and 27.8% of patients treated with infliximab had a favorable overall response (P = 0.89), and at week 22, 20.4% of the placebo group and 16.7% of the infliximab group had a favorable response (P = 0.62). In addition, the 2 groups did not differ in any of the secondary end points over the 22 weeks of the trial. Severe adverse events reported in the infliximab group did not differ from those observed in previous studies.

Conclusion

This randomized, double-blind, placebo-controlled study of an anti-TNF agent did not show any evidence of efficacy of infliximab in primary SS.

Primary Sjögren's syndrome (SS) is an autoimmune disorder characterized by lymphocytic infiltration of the salivary and lacrimal glands, leading to xerostomia and xerophthalmia and systemic production of autoantibodies (1). This syndrome, the prevalence of which is estimated to be 0.2–0.5% in the general population, is as common as rheumatoid arthritis and is often complicated by extraglandular manifestations. The most frequent clinical manifestations are dryness, fatigue, arthralgia, and/or nonerosive polyarthritis.

The pathogenesis of primary SS is dominated by 2 phenomena: a destruction of the glandular epithelial cells (acinus), which are subjected to signals inducing their apoptosis (2), and a glandular neurodegeneration, which could explain the occurrence of very severe cases of sicca syndrome, in which the destruction of the acinus does not exceed 50% of the glandular epithelial cells. This latter phenomenon could be linked to the presence of autoantibodies specific to the glandular muscarinic receptors (3), but also could be linked to the direct neurotoxic action of cytokines such as tumor necrosis factor α (TNFα) and interleukin-1 (IL-1) (4).

TNFα could be a key element in the pathogenesis of primary SS. Both in animal models of primary SS and in humans, the overexpression of TNFα has been detected in glandular lesions (5, 6). TNFα can be secreted by CD4+ T lymphocytes and mononuclear cells infiltrating the glands, but is also secreted by epithelial cells (6). The intraglandular synthesis of TNFα potentially has 3 consequences: the destruction of the acinus by the up-regulation of Fas at the surface of the glandular epithelial cells (7) and stimulation of the secretion of type 2 and type 9 metalloproteases by epithelial cells (8), the overexpression of chemokines, notably macrophage inflammatory protein 1 and RANTES, by the glandular epithelial cells attracting lymphocytes in exocrine glands (9), and the inhibition of the neuro–exocrine junction (4).

There is no effective treatment for patients with primary SS. Most treatments target the symptoms (by use of artificial tears and prosecretory drugs) (10). Immunosuppressive treatment has not been shown to be useful. Results of a study involving the NOD mouse revealed that inhibition of TNFα with a soluble p55 TNF receptor coupled to polyethylene glycol prevented the appearance of symptoms of sicca, reduced the lymphoid infiltration of the salivary glands, and decreased the expression of TNFα, IL-1, interferon-γ, IL-8, and RANTES in the salivary and lachrymal glands (11).

Recently, a pilot open-label study involving 16 patients with primary SS treated with 3 mg/kg of infliximab at weeks 0, 2, and 6 yielded impressive results at weeks 10 and 14 in the reduction of fatigue, joint pain, and symptoms of sicca (12). To confirm these results, we conducted a multicenter, randomized, double-blind, placebo-controlled trial to evaluate the effect of infliximab in primary SS, known as the Trial of Remicade In Primary Sjögren's Syndrome (TRIPSS) study.

PATIENTS AND METHODS

Patients.

A total of 103 patients with primary SS in 15 clinical centers in France and Belgium were enrolled in the study between September 2001 and September 2002. The protocol was reviewed and approved by the institutional review board of Strasbourg (France). All patients gave their written informed consent. Patients were eligible for the study if they fulfilled the new American-European Consensus Group criteria for SS (focus score ≥1 or tested positive for anti-Ro/SSA or anti-La/SSB) (13) and had active disease. To assess the activity of the disease, we used 3 visual analog scales (VAS) (0–100 mm) that evaluated joint pain (ranging from 0 for absence of joint pain to 100 for worst imaginable joint pain), fatigue (ranging from 0 for absence of fatigue to 100 for worst imaginable fatigue), and the most disturbing buccal, ocular, skin, vaginal, and bronchial dryness (ranging from 0 for absence of dryness to 100 for worst imaginable dryness). Most of the patients chose the buccal (53%) or ocular (38%) forms as exhibiting the most disturbing dryness. Patients had active disease if their values were >50 mm on 2 of the 3 VAS.

Patients were randomly assigned to receive infliximab infusions (5 mg/kg) or a placebo (same vehicle without active drug) at weeks 0, 2, and 6 and were followed up for 22 weeks. The drug and placebo were indistinguishable in appearance. Randomization was performed by use of a computer-generated list stratified by site. Treatments were centrally assigned after facsimile verification of the correctness of inclusion criteria. Neither the persons in charge of the study nor the patients were aware of the treatment assignments.

Patients receiving pilocarpine, methotrexate, azathioprine, or 6-mercaptopurine had to discontinue usage. Hydroxychloroquine or corticosteroids (≤15 mg/day) could be taken at the same dosage, but no new immunosuppressive therapy could be introduced.

The primary end point was the overall response to treatment. A favorable overall response was defined as the patient having a ≥30% improvement between weeks 0 and 10 in the values on 2 of the 3 VAS measuring joint pain, fatigue, and the most disturbing dryness. Secondary end points were values on each VAS separately, the number of tender and swollen joints, the basal salivary flow rate, the focus score on labial salivary gland biopsy, results of the Schirmer test for lacrimal gland function, the level of C-reactive protein (CRP), and the erythrocyte sedimentation rate (ESR) evaluated at weeks 0, 10, and 22, as well as quality of life evaluated by use of the generic Short Form 36 (SF-36) questionnaire (14) administered at weeks 0, 10, and 22.

Methods.

Serum samples were collected at weeks 0, 10, and 22, and were divided into aliquots and stored at −80°C until used in the centralized immunobiologic analysis. Anti-Ro/SSA (60 kd), anti-Ro/SSA (52 kd), and anti-La/SSB antibodies were detected by enzyme-linked immunosorbent assay (ELISA) using human recombinant 60-kd Ro, 52-kd Ro, and La antigens, respectively (Varelisa kit; Pharmacia, Freiburg, Germany), according to the manufacturer's instructions. Autoantibodies against double-stranded DNA (dsDNA) were detected by ELISA with use of the Kallestad IgG and IgM anti-dsDNA kit (Bio-Rad, Marne La Coquette, France) following the manufacturer's recommendations. Positive sera and sera with equivocal results (n = 5) were tested by ELISA against recombinant plasmid dsDNA (Varelisa kit; Pharmacia) to confirm and quantify IgG and IgM anti-dsDNA antibodies. Quantification of serum gamma globulin was performed by serum protein electrophoresis with use of Hydragel protein gels in conjunction with the semiautomated Hydrasis instrument and Hyris densitometer (Sebia, Issy, Les-Moulineaux, France). Serum IgG, IgM, and IgA levels were measured by nephelemetry on a Behring nephelemeter analyser II with monospecific antisera from the same manufacturer (Behring, Marburg, Germany).

Labial salivary gland biopsy was performed before treatment and at week 10. If a biopsy was performed during the year preceding the patient's inclusion in the study, its results were used as the pretreatment biopsy results. The biopsy samples were examined in a blinded manner by an expert in primary SS pathology (AJ). We evaluated the Chisholm score (scale 0–4, evaluating lesions on labial salivary gland biopsy samples), the focus score (the number of infiltrates of >50 mononuclear cells/4 mm2), the infiltrate semiquantitatively, and the aspect of the acinus and the ducts.

Safety evaluations, which included all reports of adverse events, were conducted throughout the study.

Statistical analysis.

Sample size calculations for this trial were based on the ability to detect an absolute difference of 30% in the primary outcome between the 2 treatment groups. Assuming that 20% of participants would show a response in the placebo group and 50% in the group receiving infliximab, we estimated the target sample size at 49 participants in each group (allowing for a 20% dropout rate, 2-tailed test, α = 0.05, 1 − β = 0.8).

In the data analysis, investigators were unaware of the treatment group allocation. Data on efficacy were analyzed for an intent-to-treat population, defined as all patients who underwent randomization and received at least one dose of the study medication. Missing values were imputed for the analysis with the use of a last observation carried forward method. Baseline parameters are expressed as the mean and SD for quantitative data and percentages for categorical variables. Chi-square or Fisher's exact tests were used, when appropriate, to assess differences between the infliximab and placebo groups for categorical variables at weeks 10 and 22. To compare mean differences (between weeks 10 and 0, and 22 and 0) between groups, we used the Student's unpaired 2-tailed t-test or Mann-Whitney U test, when appropriate. Non-prespecified subgroup analyses were performed. For statistical analysis of all tests, we used the SAS version 8.2 software package (SAS, Cary, NC), and a P value of less than 0.05 was considered significant.

RESULTS

A total of 134 patients were assessed for eligibility, resulting in an initial inclusion of 111 patients, of whom 103 were randomized to receive treatment; the reasons for noninclusion are shown in Figure 1. Fifty-four patients were randomized to receive infliximab and 49 to receive placebo.

Figure 1.

Profile of the Trial of Remicade (infliximab) In Primary Sjögren's Syndrome.

The baseline data did not differ between the infliximab and placebo groups (Table 1). At week 10, 26.5% of patients receiving placebo and 27.8% of patients treated with infliximab fulfilled the definition of response (≥30% improvement as measured on 2 of the 3 VAS) (P = 0.89). At week 22, 20.4% of the placebo group and 16.7% of the patients treated with infliximab had shown a response to treatment (P = 0.62). The 2 groups did not differ in their scores on each of the 3 VAS during the study (Figure 2). Similarly, the 2 groups showed no differences in any of the secondary end points. Values for the results of the Schirmer test, basal salivary flow rate, tender and swollen joint counts, ESR, and CRP at weeks 10 and 22 are shown in Table 2.

Table 1. Baseline demographics and clinical characteristics of the study patients*
 Placebo (n = 49)Infliximab (n = 54)
  • *

    Except where otherwise indicated, values are the mean ± SD. ESR = erythrocyte sedimentation rate; CRP = C-reactive protein; VAS = visual analog scale.

Age, years53.8 ± 11.454.4 ± 10.4
Time since diagnosis, years4.9 ± 5.64.0 ± 5.5
Focus score ≥1, %97.691.7
Anti-SSA, %57.150.0
Anti-SSB, %32.735.3
ESR, mm/hour19.4 ± 23.319.7 ± 14.9
CRP level, mg/liter5.3 ± 4.16.3 ± 7.6
Pain VAS, mm61.1 ± 26.361.6 ± 23.4
Fatigue VAS, mm73.4 ± 17.775.0 ± 14.5
Dryness VAS, mm79.4 ± 16.178.5 ± 16.4
Salivary flow rate, ml/minute0.16 ± 0.230.19 ± 0.27
Schirmer test, mm6.3 ± 8.18.4 ± 8.2
Swollen joint count0.7 ± 2.01.3 ± 3.5
Tender joint count7.8 ± 8.28.8 ± 8.0
Patients taking steroids, %30.638.9
Patients taking hydroxychloroquine, %38.840.7
Figure 2.

Scores on the individual visual analog scales (VAS) in the infliximab group (shaded lines) and in the placebo group (solid lines). Bars show the mean ± SD mm.

Table 2. Clinical and biologic changes in the 2 study groups from baseline to week 22*
 Week 10 change from baselineWeek 22 change from baseline
Placebo (n = 49)Infliximab (n = 54)PPlacebo (n = 49)Infliximab (n = 54)P
  • *

    Except where otherwise indicated, values are the mean ± SD. See Table 1 for definitions.

  • Determination of gamma globulin, IgG, IgA, and IgM was performed in 77 patients (38 in the placebo group and 39 in the infliximab group).

30% decrease in 2 of 3 VAS, %26.527.80.8920.416.70.62
30% decrease in pain VAS, %26.524.10.7726.520.40.46
30% decrease in fatigue VAS, %30.631.50.9224.524.10.96
30% decrease in dryness VAS, %22.522.20.9816.316.70.96
Salivary flow rate, ml/minute0.01 ± 0.210.05 ± 0.170.300.02 ± 0.190.03 ± 0.150.24
Schirmer test, mm0.7 ± 8.32.1 ± 5.90.341.5 ± 6.90.9 ± 5.50.75
Swollen joint count0.0 ± 2.2−0.5 ± 3.30.44−0.3 ± 1.7−0.4 ± 3.30.75
Tender joint count−2.3 ± 6.9−3.5 ± 8.70.39−2.3 ± 7.6−2.4 ± 9.70.97
ESR, mm/hour0.9 ± 10.1−0.8 ± 11.00.45−0.9 ± 7.5−0.8 ± 9.30.97
CRP, mg/liter1.0 ± 4.2−0.4 ± 6.70.25−0.5 ± 2.8−0.4 ± 9.80.96
Gamma globulin, gm/liter0.12 ± 1.161.03 ± 1.940.020.13 ± 1.490.78 ± 2.080.05
IgG, gm/liter0.06 ± 1.190.87 ± 2.470.100.03 ± 2.280.74 ± 2.430.24
IgA, gm/liter0.03 ± 0.560.13 ± 0.420.400.09 ± 0.440.16 ± 0.460.56
IgM, gm/liter−0.01 ± 0.400.48 ± 0.870.0050.04 ± 0.410.34 ± 0.450.001

In addition, the 2 groups did not differ in quality of life as assessed by the physical and mental health components of the SF-36 questionnaire between weeks 0 and 10. The changes in the physical health component scores were a mean ± SD 4.3 ± 8.1 and 2.2 ± 6.3 in the infliximab and placebo groups, respectively (P = 0.17), and the changes in the mental health component scores were 2.1 ± 11.8 and 4.9 ± 10.8 in the infliximab and placebo groups, respectively (P = 0.24) (Figure 3).

Figure 3.

Scores on the composite physical health and mental health components of the generic Short-Form 36 questionnaire at weeks 0 and 10 in the infliximab (hatched bars) and placebo (solid bars) groups. Bars show the mean and SD scores.

An analyzable labial salivary gland biopsy specimen was available from 57 patients at baseline and at week 10. The baseline focus score was 1.5 ± 1.4 for the infliximab group and 1.9 ± 1.6 for the placebo group. The change in focus score did not differ between the infliximab group (−0.7 ± 1.7) and the placebo group (−0.9 ± 1.7) (P = 0.46).

Data from the centralized analysis of serum to measure changes in gamma globulin, Ig, and autoantibody levels were available at baseline, week 10, and/or week 22 in 77 patients (38 in the placebo group, 39 in the infliximab group). The gamma globulin level increased significantly in the infliximab group, mainly because of an increase in the IgM level (Table 2). We did not observe any change in the number of patients testing positive for anti-Ro/SSA or anti-La/SSB. At baseline, only 1 patient had anti-DNA antibodies of the IgG isotype at a low titer; this patient, who was without any sign of lupus and was treated with placebo, remained anti-DNA positive at the end of the study. Four additional patients in the infliximab group (10.3%) showed anti-DNA antibodies of the IgG isotype (2 patients) and the IgG + IgM isotype (2 patients) at the end of the study (Table 3).

Table 3. Number of patients with autoantibodies at baseline and weeks 10 or 22
 BaselineWeek 10 or 22
Placebo (n = 38)Infliximab (n = 39)Placebo (n = 38)Infliximab (n = 39)
Anti–Ro 6021172017
Anti–Ro 5217161716
Anti-La13111310
Anti-DNA1 (IgG)01 (IgG)4 (2 IgG and 2 IgG + IgM)

Seven patients experienced severe adverse events. Six of the adverse events occurred in the infliximab group (2 were infusion reactions, 1 an isolated cutaneous facial eruption without any anti-DNA antibodies, 1 autoimmune hepatitis, 1 pneumococcal septicemia, and 1 breast cancer) and 1 occurred in the placebo group (polyclonal lymph node enlargement).

DISCUSSION

Therapy that targets TNFα has emerged as being highly effective in inducing rapid and sustained clinical improvement of several inflammatory arthritides, including rheumatoid arthritis and the spondylarthropathies. Other systemic autoimmune diseases such as vasculitis can be favorably influenced by such therapy. Beyond its effect on joint inflammation, TNFα has a role in exocrine glands and can destroy the acinus and inhibit the neuro–exocrine junction, which are both characteristics of primary SS. A recent small, pilot open-label study involving 16 patients with primary SS treated with 3 mg/kg of infliximab, a TNF blocker, at weeks 0, 2, and 6 yielded impressive results at weeks 10 and 14 in reducing fatigue, joint pain, and symptoms of sicca (12).

However, our randomized controlled study did not demonstrate the clinical efficacy of infliximab, 5 mg/kg, given as monotherapy at weeks 0, 2, and 6 in patients with primary SS. The inclusion criteria in both studies were slightly different. Patients in the open study had to have one extraglandular involvement, an ESR level >25 mm/hour, or a serum gamma globulin level >14 gm/liter and not be receiving associated treatments (12). Thus, patients in the open study had more extraglandular manifestations and anti-Ro/SSA and anti-La/SSB autoantibodies, but the objective baseline evaluation of dryness was equivalent in both studies. Although no subgroups were prespecified in our study, we analyzed very cautiously the outcomes in different subgroups and did not find infliximab to be effective in the subgroups of patients with extraglandular manifestations, anti-Ro/SSA or anti-La/SSB autoantibodies, an ESR >25 mm/hour, or a serum gamma globulin level >14 gm/liter, nor was it effective in patients not receiving any associated steroids or hydroxychloroquine (data not shown).

The discrepancies between these 2 studies may be explained by their different designs. It is well known that because of the placebo effect, nonrandomized open-label studies could yield larger estimates of treatment effects than those from randomized controlled trials (15). In addition, observational studies may be more prone to bias when evaluating invasive therapies or when using “soft” outcomes (16). Interestingly, results of a recent open study of etanercept, another TNF blocker, in 15 patients with primary SS did not reveal any improvement of lachrymal and salivary function or salivary histologic features (17).

Primary SS is now defined by the new American-European Consensus Group criteria (a focus score ≥1 or positive results for anti-Ro/SSA or anti-La/SSB) (13), and these criteria were used in the present study. However, in contrast to studies of rheumatoid arthritis and the spondylarthropathies, validated activity indexes and outcomes measures are not available for clinical trials of primary SS. Our objective was the improvement of dryness, fatigue, and joint pain responsible for a marked decrease in the quality of life of the patients with primary SS. Therefore, we chose a patient-reported outcome as the primary end point. This composite outcome consisted of the associations of 3 VAS that explored these domains. The choice of a “soft” outcome, the patient-reported outcome, as the primary end point could be criticized. However, none of our secondary “hard” end points—Schirmer test values, salivary flow rate, ESR, level of CRP, or salivary histologic features—significantly differed between the infliximab and placebo groups.

The lack of change in sicca symptoms and signs could be due to the preexistence of the too important destruction of the glandular tissue and to the presence of irreversible damage. However, we did not find infliximab to be effective in the subgroup of patients with a more recent diagnosis (less than the median, i.e., 2.6 years versus more) (data not shown). The lack of change in fatigue, number of tender and swollen joints, ESR, and CRP level is more surprising, considering what is known about rheumatoid arthritis and the spondylarthropathies. These findings could support the possibility that the mechanisms of tender and swollen joints might be different in primary SS than in rheumatoid arthritis. Of note, only 23 of 103 patients (11 in the placebo group and 12 in the infliximab group) had swollen joints at baseline and only 16 patients had 2 or more swollen joints. The mean ESR was increased at baseline (20 mm in the first hour), but this increase was probably related to an increased gamma globulin level rather than to inflammation. Indeed, the mean CRP level was within the normal range of 5 mg/liter.

Severe adverse events reported in the infliximab group did not differ from those observed in previous studies. The increase of the gamma globulin level with infliximab treatment is surprising and was not previously described in patients with rheumatoid arthritis or Crohn's disease. Interestingly, a significant increase of IgG was already noted in the pilot open-label study (12), but the authors attributed this increase to 2 patients with unusually high IgG levels. In contrast to rheumatoid arthritis or Crohn's disease, which are Th1-mediated diseases, primary SS can be driven by both Th1 and Th2 responses, and the latter is responsible for the hypergammaglobulinemia seen frequently in this disease. The suppression of the Th1 response by TNF blockers could favor the Th2 response and the increased Ig level. The appearance of anti-DNA antibodies of the IgG isotype in 10.3% of the patients in the infliximab group could be linked to the same phenomenon. Interestingly, the proportion of occurrence of anti-DNA antibodies was the same as in other diseases such as the spondylarthropathies, but in the latter, they were never of the IgG isotype (18).

Thus, this first randomized, double-blind, placebo-controlled study of an anti-TNF agent in primary SS did not show any evidence of efficacy of infliximab. Whether TNF inhibitors could be efficient in some subgroups of patients deserves further study. Finally, our study demonstrates that randomized controlled trials of therapy for primary SS are possible, and further study of new drugs should be encouraged.

Addendum.

Since the time this article was accepted for publication, an article appeared (19) indicating that TNF deficiency failed to protect BAFF-transgenic mice against autoimmunity. BAFF-transgenic mice developed SS-like features, and invalidation of TNF in these mice did not modify secretion of autoantibodies and salivary lesions. These findings suggest an explanation for the inefficacy of TNF blockers in our patients.

Acknowledgements

We are indebted to all of the other physicians who contributed patients to the study: L. Guillevin (Bobigny), O. Meyer (Paris), M. Alcalay (Poitiers), B. Grosbois (Rennes), A. Saraux (Brest), R. Treves (Limoges), X. Le Loet (Rouen), D. Goldberg (Paris). We are also indebted to the coordinators of the ophthalmic examinations: C. Baudouin (Paris) and M. Labetoulle (Le Kremlin Bicêtre), and to the patients who participated, especially considering their great hope for this new treatment and their disappointment with the results of the study.

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